The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.
An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.
Proteins obtained from various species of Xenopus. Included here are proteins from the African clawed frog (XENOPUS LAEVIS). Many of these proteins have been the subject of scientific investigations in the area of MORPHOGENESIS and development.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.
Profound physical changes during maturation of living organisms from the immature forms to the adult forms, such as from TADPOLES to frogs; caterpillars to BUTTERFLIES.
A mature haploid female germ cell extruded from the OVARY at OVULATION.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The developmental stage that follows BLASTULA or BLASTOCYST. It is characterized by the morphogenetic cell movements including invagination, ingression, and involution. Gastrulation begins with the formation of the PRIMITIVE STREAK, and ends with the formation of three GERM LAYERS, the body plan of the mature organism.
The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
Phospholipoglycoproteins produced in the fat body of egg-laying animals such as non-mammalian VERTEBRATES; ARTHROPODS; and others. Vitellogenins are secreted into the HEMOLYMPH, and taken into the OOCYTES by receptor-mediated ENDOCYTOSIS to form the major yolk proteins, VITELLINS. Vitellogenin production is under the regulation of steroid hormones, such as ESTRADIOL and JUVENILE HORMONES in insects.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
An early non-mammalian embryo that follows the MORULA stage. A blastula resembles a hollow ball with the layer of cells surrounding a fluid-filled cavity (blastocele). The layer of cells is called BLASTODERM.
Synthetic transcripts of a specific DNA molecule or fragment, made by an in vitro transcription system. This cRNA can be labeled with radioactive uracil and then used as a probe. (King & Stansfield, A Dictionary of Genetics, 4th ed)
A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
The complex processes of initiating CELL DIFFERENTIATION in the embryo. The precise regulation by cell interactions leads to diversity of cell types and specific pattern of organization (EMBRYOGENESIS).
The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.
The outer of the three germ layers of an embryo.
The process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).
Preparations of cell constituents or subcellular materials, isolates, or substances.
Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.
Chromatophores (large pigment cells of fish, amphibia, reptiles and many invertebrates) which contain melanin. Short term color changes are brought about by an active redistribution of the melanophores pigment containing organelles (MELANOSOMES). Mammals do not have melanophores; however they have retained smaller pigment cells known as MELANOCYTES.
Constituent of the 50S subunit of prokaryotic ribosomes containing about 120 nucleotides and 34 proteins. It is also a constituent of the 60S subunit of eukaryotic ribosomes. 5S rRNA is involved in initiation of polypeptide synthesis.
One of several general transcription factors that are specific for RNA POLYMERASE III. It is a zinc finger (ZINC FINGERS) protein and is required for transcription of 5S ribosomal genes.
The processes occurring in early development that direct morphogenesis. They specify the body plan ensuring that cells will proceed to differentiate, grow, and diversify in size and shape at the correct relative positions. Included are axial patterning, segmentation, compartment specification, limb position, organ boundary patterning, blood vessel patterning, etc.
The entire nerve apparatus, composed of a central part, the brain and spinal cord, and a peripheral part, the cranial and spinal nerves, autonomic ganglia, and plexuses. (Stedman, 26th ed)
Transport proteins that carry specific substances in the blood or across cell membranes.
The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.
A family of histone molecular chaperones that play roles in sperm CHROMATIN decondensation and CHROMATIN ASSEMBLY in fertilized eggs. They were originally discovered in XENOPUS egg extracts as histone-binding factors that mediate nucleosome formation in vitro.
A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.
The rate dynamics in chemical or physical systems.
ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.
The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed)
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.
The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.
A cartilaginous rod of mesodermal cells at the dorsal midline of all CHORDATE embryos. In lower vertebrates, notochord is the backbone of support. In the higher vertebrates, notochord is a transient structure, and segments of the vertebral column will develop around it. Notochord is also a source of midline signals that pattern surrounding tissues including the NEURAL TUBE development.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.
Proteins prepared by recombinant DNA technology.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Activins are produced in the pituitary, gonads, and other tissues. By acting locally, they stimulate pituitary FSH secretion and have diverse effects on cell differentiation and embryonic development. Activins are glycoproteins that are hetero- or homodimers of INHIBIN-BETA SUBUNITS.
Membrane transporters that co-transport two or more dissimilar molecules in the same direction across a membrane. Usually the transport of one ion or molecule is against its electrochemical gradient and is "powered" by the movement of another ion or molecule with its electrochemical gradient.
The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.
VERTEBRATES belonging to the class amphibia such as frogs, toads, newts and salamanders that live in a semiaquatic environment.
The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.
Elements of limited time intervals, contributing to particular results or situations.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
Protein kinase that drives both the mitotic and meiotic cycles in all eukaryotic organisms. In meiosis it induces immature oocytes to undergo meiotic maturation. In mitosis it has a role in the G2/M phase transition. Once activated by CYCLINS; MPF directly phosphorylates some of the proteins involved in nuclear envelope breakdown, chromosome condensation, spindle assembly, and the degradation of cyclins. The catalytic subunit of MPF is PROTEIN P34CDC2.
A group of adenine ribonucleotides in which the phosphate residues of each adenine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
The fertilized OVUM resulting from the fusion of a male and a female gamete.
Undifferentiated cells resulting from cleavage of a fertilized egg (ZYGOTE). Inside the intact ZONA PELLUCIDA, each cleavage yields two blastomeres of about half size of the parent cell. Up to the 8-cell stage, all of the blastomeres are totipotent. The 16-cell MORULA contains outer cells and inner cells.
Proteins encoded by homeobox genes (GENES, HOMEOBOX) that exhibit structural similarity to certain prokaryotic and eukaryotic DNA-binding proteins. Homeodomain proteins are involved in the control of gene expression during morphogenesis and development (GENE EXPRESSION REGULATION, DEVELOPMENTAL).
Proteins which are found in eggs (OVA) from any species.
A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.
Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.
Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)
A process of complicated morphogenetic cell movements that reorganizes a bilayer embryo into one with three GERM LAYERS and specific orientation (dorsal/ventral; anterior/posterior). Gastrulation describes the germ layer development of a non-mammalian BLASTULA or that of a mammalian BLASTOCYST.
Morphological and physiological development of EMBRYOS.
A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.
The plasma membrane of the egg.
Detection of RNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
A large collection of DNA fragments cloned (CLONING, MOLECULAR) from a given organism, tissue, organ, or cell type. It may contain complete genomic sequences (GENOMIC LIBRARY) or complementary DNA sequences, the latter being formed from messenger RNA and lacking intron sequences.
Proteins containing a region of conserved sequence, about 200 amino acids long, which encodes a particular sequence specific DNA binding domain (the T-box domain). These proteins are transcription factors that control developmental pathways. The prototype of this family is the mouse Brachyury (or T) gene product.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.
An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.
Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.
Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.
The two longitudinal ridges along the PRIMITIVE STREAK appearing near the end of GASTRULATION during development of nervous system (NEURULATION). The ridges are formed by folding of NEURAL PLATE. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the NEURAL TUBE.
A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.
Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize.
Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
Bone-growth regulatory factors that are members of the transforming growth factor-beta superfamily of proteins. They are synthesized as large precursor molecules which are cleaved by proteolytic enzymes. The active form can consist of a dimer of two identical proteins or a heterodimer of two related bone morphogenetic proteins.
Natural hormones secreted by the THYROID GLAND, such as THYROXINE, and their synthetic analogs.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
The inner of the three germ layers of an embryo.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)
The relationship between the dose of an administered drug and the response of the organism to the drug.
A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.
General term for a number of inherited defects of amino acid metabolism in which there is a deficiency or absence of pigment in the eyes, skin, or hair.
A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
The family of true toads belonging to the order Anura. The genera include Bufo, Ansonia, Nectophrynoides, and Atelopus.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.
Short chains of RNA (100-300 nucleotides long) that are abundant in the nucleus and usually complexed with proteins in snRNPs (RIBONUCLEOPROTEINS, SMALL NUCLEAR). Many function in the processing of messenger RNA precursors. Others, the snoRNAs (RNA, SMALL NUCLEOLAR), are involved with the processing of ribosomal RNA precursors.
Wnt proteins are a large family of secreted glycoproteins that play essential roles in EMBRYONIC AND FETAL DEVELOPMENT, and tissue maintenance. They bind to FRIZZLED RECEPTORS and act as PARACRINE PROTEIN FACTORS to initiate a variety of SIGNAL TRANSDUCTION PATHWAYS. The canonical Wnt signaling pathway stabilizes the transcriptional coactivator BETA CATENIN.
The sum of the weight of all the atoms in a molecule.
The striated muscle groups which move the LARYNX as a whole or its parts, such as altering tension of the VOCAL CORDS, or size of the slit (RIMA GLOTTIDIS).
The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.
Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.
Cellular proteins encoded by the c-mos genes (GENES, MOS). They function in the cell cycle to maintain MATURATION PROMOTING FACTOR in the active state and have protein-serine/threonine kinase activity. Oncogenic transformation can take place when c-mos proteins are expressed at the wrong time.
A secreted matrix metalloproteinase that is believed to play a role in EXTRACELLULAR MATRIX remodeling and cell fate determination during normal and pathological processes. Matrix metalloproteinase 11 was originally isolated in primary BREAST NEOPLASMS and may be involved in the process of tumorigenesis.
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.
The region in the dorsal ECTODERM of a chordate embryo that gives rise to the future CENTRAL NERVOUS SYSTEM. Tissue in the neural plate is called the neuroectoderm, often used as a synonym of neural plate.
Proteins that are preferentially expressed or upregulated during FETAL DEVELOPMENT.
Contractile tissue that produces movement in animals.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
The process by which a DNA molecule is duplicated.
The relationships of groups of organisms as reflected by their genetic makeup.
Characteristic restricted to a particular organ of the body, such as a cell type, metabolic response or expression of a particular protein or antigen.
Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.
Complexes of RNA-binding proteins with ribonucleic acids (RNA).
DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.
Paired, segmented masses of MESENCHYME located on either side of the developing spinal cord (neural tube). Somites derive from PARAXIAL MESODERM and continue to increase in number during ORGANOGENESIS. Somites give rise to SKELETON (sclerotome); MUSCLES (myotome); and DERMIS (dermatome).
Biologically active DNA which has been formed by the in vitro joining of segments of DNA from different sources. It includes the recombination joint or edge of a heteroduplex region where two recombining DNA molecules are connected.
A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.
Goosecoid protein is a homeodomain protein that was first identified in XENOPUS. It is found in the SPEMANN ORGANIZER of VERTEBRATES and plays an important role in neuronal CELL DIFFERENTIATION and ORGANOGENESIS.
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
The physiological renewal, repair, or replacement of tissue.

Bcl-2 regulates amplification of caspase activation by cytochrome c. (1/11334)

Caspases, a family of specific proteases, have central roles in apoptosis [1]. Caspase activation in response to diverse apoptotic stimuli involves the relocalisation of cytochrome c from mitochondria to the cytoplasm where it stimulates the proteolytic processing of caspase precursors. Cytochrome c release is controlled by members of the Bcl-2 family of apoptosis regulators [2] [3]. The anti-apoptotic members Bcl-2 and Bcl-xL may also control caspase activation independently of cytochrome c relocalisation or may inhibit a positive feedback mechanism [4] [5] [6] [7]. Here, we investigate the role of Bcl-2 family proteins in the regulation of caspase activation using a model cell-free system. We found that Bcl-2 and Bcl-xL set a threshold in the amount of cytochrome c required to activate caspases, even in soluble extracts lacking mitochondria. Addition of dATP (which stimulates the procaspase-processing factor Apaf-1 [8] [9]) overcame inhibition of caspase activation by Bcl-2, but did not prevent the control of cytochrome c release from mitochondria by Bcl-2. Cytochrome c release was accelerated by active caspase-3 and this positive feedback was negatively regulated by Bcl-2. These results provide evidence for a mechanism to amplify caspase activation that is suppressed at several distinct steps by Bcl-2, even after cytochrome c is released from mitochondria.  (+info)

Angiotensin II type 1 receptor-mediated inhibition of K+ channel subunit kv2.2 in brain stem and hypothalamic neurons. (2/11334)

Angiotensin II (Ang II) has powerful modulatory actions on cardiovascular function that are mediated by specific receptors located on neurons within the hypothalamus and brain stem. Incubation of neuronal cocultures of rat hypothalamus and brain stem with Ang II elicits an Ang II type 1 (AT1) receptor-mediated inhibition of total outward K+ current that contributes to an increase in neuronal firing rate. However, the exact K+ conductance(s) that is inhibited by Ang II are not established. Pharmacological manipulation of total neuronal outward K+ current revealed a component of K+ current sensitive to quinine, tetraethylammonium, and 4-aminopyridine, with IC50 values of 21.7 micromol/L, 1.49 mmol/L, and 890 micromol/L, respectively, and insensitive to alpha-dendrotoxin (100 to 500 nmol/L), charybdotoxin (100 to 500 nmol/L), and mast cell degranulating peptide (1 micromol/L). Collectively, these data suggest the presence of Kv2.2 and Kv3.1b. Biophysical examination of the quinine-sensitive neuronal K+ current demonstrated a macroscopic conductance with similar biophysical properties to those of Kv2.2 and Kv3.1b. Ang II (100 nmol/L), in the presence of the AT2 receptor blocker PD123,319, elicited an inhibition of neuronal K+ current that was abolished by quinine (50 micromol/L). Reverse transcriptase-polymerase chain reaction analysis confirmed the presence of Kv2.2 and Kv3.1b mRNA in these neurons. However, Western blot analyses demonstrated that only Kv2.2 protein was present. Coexpression of Kv2.2 and the AT1 receptor in Xenopus oocytes demonstrated an Ang II-induced inhibition of Kv2.2 current. Therefore, these data suggest that inhibition of Kv2.2 contributes to the AT1 receptor-mediated reduction of neuronal K+ current and subsequently to the modulation of cardiovascular function.  (+info)

Molecular dynamics of the sodium channel pore vary with gating: interactions between P-segment motions and inactivation. (3/11334)

Disulfide trapping studies have revealed that the pore-lining (P) segments of voltage-dependent sodium channels undergo sizable motions on a subsecond time scale. Such motions of the pore may be necessary for selective ion translocation. Although traditionally viewed as separable properties, gating and permeation are now known to interact extensively in various classes of channels. We have investigated the interaction of pore motions and voltage-dependent gating in micro1 sodium channels engineered to contain two cysteines within the P segments. Rates of catalyzed internal disulfide formation (kSS) were measured in K1237C+W1531C mutant channels expressed in oocytes. During repetitive voltage-clamp depolarizations, increasing the pulse duration had biphasic effects on the kSS, which first increased to a maximum at 200 msec and then decreased with longer depolarizations. This result suggested that occupancy of an intermediate inactivation state (IM) facilitates pore motions. Consistent with the known antagonism between alkali metals and a component of slow inactivation, kSS varied inversely with external [Na+]o. We examined the converse relationship, namely the effect of pore flexibility on gating, by measuring recovery from inactivation in Y401C+E758C (YC/EC) channels. Under oxidative conditions, recovery from inactivation was slower than in a reduced environment in which the spontaneous YC/EC cross-link is disrupted. The most prominent effects were slowing of a component with intermediate recovery kinetics, with diminution of its relative amplitude. We conclude that occupancy of an intermediate inactivation state facilitates motions of the P segments; conversely, flexibility of the P segments alters an intermediate component of inactivation.  (+info)

Histone octamer transfer by a chromatin-remodeling complex. (4/11334)

RSC, an abundant, essential chromatin-remodeling complex related to SWI/SNF complex, catalyzes the transfer of a histone octamer from a nucleosome core particle to naked DNA. The newly formed octamer-DNA complex is identical with a nucleosome in all respects. The reaction requires ATP and involves an activated RSC-nucleosome intermediate. The mechanism may entail formation of a duplex displacement loop on the nucleosome, facilitating the entry of exogeneous DNA and the release of the endogenous molecule.  (+info)

KCNQ4, a novel potassium channel expressed in sensory outer hair cells, is mutated in dominant deafness. (5/11334)

Potassium channels regulate electrical signaling and the ionic composition of biological fluids. Mutations in the three known genes of the KCNQ branch of the K+ channel gene family underlie inherited cardiac arrhythmias (in some cases associated with deafness) and neonatal epilepsy. We have now cloned KCNQ4, a novel member of this branch. It maps to the DFNA2 locus for a form of nonsyndromic dominant deafness. In the cochlea, it is expressed in sensory outer hair cells. A mutation in this gene in a DFNA2 pedigree changes a residue in the KCNQ4 pore region. It abolishes the potassium currents of wild-type KCNQ4 on which it exerts a strong dominant-negative effect. Whereas mutations in KCNQ1 cause deafness by affecting endolymph secretion, the mechanism leading to KCNQ4-related hearing loss is intrinsic to outer hair cells.  (+info)

Phosphorylation of yeast TBP by protein kinase CK2 reduces its specific binding to DNA. (6/11334)

Protein kinase CK2 is a ubiquitous Ser/Thr kinase which phosphorylates a large number of proteins including several transcription factors. Recombinant Xenopus laevis CK2 phosphorylates both recombinant Saccharomyces cerevisiae and Schizosaccharomyces pombe TATA binding protein (TBP). The phosphorylation of TBP by CK2 reduces its binding activity to the TATA box. CK2 copurifies with the transcription factor IID (TFIID) complex from HeLa cell extracts and phosphorylates several of the TBP-associated factors within TFIID. Taken together these findings argue for a role of CK2 in the control of transcription by RNA polymerase II through the modulation of the binding activity of TBP to the TATA box.  (+info)

In vivo formation of Cu,Zn superoxide dismutase disulfide bond in Escherichia coli. (7/11334)

We have found that the in vivo folding of periplasmic Escherichia coli Cu,Zn superoxide dismutase is assisted by DsbA, which catalyzes the efficient formation of its single disulfide bond, whose integrity is essential to ensure full catalytic activity to the enzyme. In line with these findings, we also report that the production of recombinant Xenopus laevis Cu,Zn superoxide dismutase is enhanced when the enzyme is exported in the periplasmic space or is expressed in thioredoxin reductase mutant strains. Our data show that inefficient disulfide bond oxidation in the bacterial cytoplasm inhibits Cu,Zn superoxide dismutase folding in this cellular compartment.  (+info)

Cu(II) inhibition of the proton translocation machinery of the influenza A virus M2 protein. (8/11334)

The homotetrameric M2 integral membrane protein of influenza virus forms a proton-selective ion channel. An essential histidine residue (His-37) in the M2 transmembrane domain is believed to play an important role in the conduction mechanism of this channel. Also, this residue is believed to form hydrogen-bonded interactions with the ammonium group of the anti-viral compound, amantadine. A molecular model of this channel suggests that the imidazole side chains of His-37 from symmetry-related monomers of the homotetrameric pore converge to form a coordination site for transition metals. Thus, membrane currents of oocytes of Xenopus laevis expressing the M2 protein were recorded when the solution bathing the oocytes contained various transition metals. Membrane currents were strongly and reversibly inhibited by Cu2+ with biphasic reaction kinetics. The biphasic inhibition curves may be explained by a two-site model involving a fast-binding peripheral site with low specificity for divalent metal ions, as well as a high affinity site (Kdiss approximately 2 microM) that lies deep within the pore and shows rather slow-binding kinetics (kon = 18.6 +/- 0.9 M-1 s-1). The pH dependence of the interaction with the high affinity Cu2+-binding site parallels the pH dependence of inhibition by amantadine, which has previously been ascribed to protonation of His-37. The voltage dependence of the inhibition at the high affinity site indicates that the binding site lies within the transmembrane region of the pore. Furthermore, the inhibition by Cu2+ could be prevented by prior application of the reversible blocker of M2 channel activity, BL-1743, providing further support for the location of the site within the pore region of M2. Finally, substitutions of His-37 by alanine or glycine eliminated the high affinity site and resulted in membrane currents that were only partially inhibited at millimolar concentrations of Cu2+. Binding of Cu2+ to the high affinity site resulted in an approximately equal inhibition of both inward and outward currents. The wild-type protein showed very high specificity for Cu2+ and was only partially inhibited by 1 mM Ni2+, Pt2+, and Zn2+. These data are discussed in terms of the functional role of His-37 in the mechanism of proton translocation through the channel.  (+info)

TY - JOUR. T1 - Spatially and temporally regulated α6 integrin cleavage during Xenopus laevis development. AU - Demetriou, Manolis C.. AU - Stylianou, Panayiota. AU - Andreou, Maria. AU - Yiannikouri, Olga. AU - Tsaprailis, George. AU - Cress, Anne E. AU - Skourides, Paris. PY - 2008/2/15. Y1 - 2008/2/15. N2 - The α6 integrin is essential for early nervous system development in Xenopus laevis. We have previously reported a uPA cleaved form of integrin α6 (α6p), in invasive human prostate cancer tissue, whose presence correlates with increased migration and invasive capacity. We now report that α6 is cleaved during the normal development of Xenopus in a spatially and temporally controlled manner. In addition, unlike normal mammalian tissues, which lack α6p, the major form of the α6 integrin present in adult Xenopus is α6p. The protease responsible for the cleavage in mammals, uPA, is not involved in the cleavage of Xenopus α6. Finally, overexpression of a mammalian α6 mutant which ...
Recent surveys of various aquatic habitats have found detectable concentrations of several organic wastewater contaminants (OWCs). The effects of these OWCs on aquatic organisms are relatively unknown. We studied the effects of ecologically-relevant concentrations of two OWCs, acetaminophen and triclosan, on the behavior, growth, and survivorship of Xenopus laevis tadpoles. Xenopus laevis decreased activity with increased concentrations of acetaminophen, but acetaminophen had no effect on startle response, final mass, nor suvivorship. Triclosan had a negative effect on tadpole activity, but no effect on startle response. High concentrations of triclosan had a negative effect on final mass and intermediate concentrations had a positive effect on final mass relative to controls. Triclosan did not affect survivorship. Our results suggest that some aspects of amphibian larval ecology may be impacted by OWC levels currently observed in the environment, and that further increases in such concentrations could
This approach effectively reduces the size of the cDNA library to be screened and increases the probability of successful isolation of the target cDNA. The vocal apparatus of the clawed frog is designed for underwater sound production (Deuchar, 1975). The first step of this physiological process seems to involve a target site at the oocyte membrane, as shown by a variety of experimental data (4). Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by … Their large nuclei and mitochondrial masses are clearly visible in the intact oocyte. The incision is sutured with surgical silk and the frog is placed in shallow water in a small tank to allow it to recover from anesthesia before placing it in a special tank for postoperative frogs. XENOPUS OOCYTES The oocyte from the South African clawed frog Xenopus laevis is an often used functional expression system. Two species of Xenopus ...
TY - JOUR. T1 - Cloning and expression of Xenopus laevis xSox12 cDNA. AU - Komatsu, Naoki. AU - Hiraoka, Yoshiki. AU - Shiozawa, Masahide. AU - Ogawa, Motoyuki. AU - Aiso, Sadakazu. PY - 1996/3/1. Y1 - 1996/3/1. N2 - A family of SRY-related genes has been termed SOX. We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. The cDNA contained an open reading frame (ORF) coding for 470 amino acids encompassing an HMG box characteristic of the SOX family, a leucine zipper motif and glutamine-rich segments. The size of the xSox12 mRNA was determined to be 3.0 knt by Northern analysis. The ovary was the most prominent in the expression of the Sox mRNA among the various tissues of adult frog as far as examined.. AB - A family of SRY-related genes has been termed SOX. We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. The cDNA contained an open reading frame (ORF) coding for 470 amino acids encompassing an HMG box characteristic of the SOX family, a ...
BioAssay record AID 700514 submitted by ChEMBL: Modulation of human recombinant GABA-A alpha1beta1gamma2L receptor expressed in Xenopus laevis oocytes assessed as effect on GABA-induced chloride current at 0.01 uM incubated 60 seconds before addition of GABA measured after 30 seconds at holding potential -70 mV by two-microelectrode voltage clamp technique relative to control.
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The common laboratory frog Xenopus laevis has puzzled researchers because it has twice the normal number of genes. A newly published genome sequence shows why: between 15 and 20 million years ago, two different species interbred and produced a hybrid, which then mated with its parent species to eventually form a new organism with a doubled genome. The frog has since adapted to the excess by losing or disabling many of these genes.
Rödder, D., Ihlow, F., Courant, J., Secondi, J., Herrel, A., Rebelo, R., Measey, G. J., et al. (2017): Global realized niche divergence in the African clawed frog Xenopus laevis. - Ecology and Evolution 2017: 1-15; DOI: 10.1002/ece3.3010
During Xenopus laevis metamorphosis, larval-to-adult muscle conversion depends on the differential responses of adult and larval myogenic cells to thyroid hormone. Essential differences in cell growth, differentiation, and hormone-dependent life-or-death fate have been reported between cultured larval (tail) and adult (hindlimb) myogenic cells. A previous study revealed that tail notochord cells suppress terminal differentiation in adult (but not larval) myogenic cells. However, little is known about the differences in expression patterns of myogenic regulatory factors (MRF) and the satellite cell marker Pax7 between adult and larval myogenic cells. In the present study, we compared mRNA expression of these factors between the two types. At first, reverse transcription polymerase chain reaction analysis of hindlimb buds showed sequential upregulation of myf5, myogenin, myod, and mrf4 during stages 50-54, when limb buds elongate and muscles begin to form. By contrast, in the tail, there was no such
Free Online Library: Twin Xenopus laevis embryos appearing from flattened eggs.(Report) by Japan Academy Proceedings Series B: Physical and Biological Sciences; Agricultural industry Engineering and manufacturing Biological sciences Common plantanna Genetic aspects Research Embryonic development Analysis Gene expression
Ca2+-activated Cl- channels (CaCCs) participate in many important physiological processes. However, the lack of effective and selective blockers has hindered the study of these channels, mostly due to the lack of good assay system. Here, we have developed a reliable drug screening method for better blockers of CaCCs, using the endogeneous CaCCs in Xenopus laevis oocytes and two-electrode voltage-clamp (TEVC) technique. Oocytes were prepared with a treatment of Ca2+ ionophore, which was followed by a treatment of thapsigargin which depletes Ca2+ stores to eliminate any contribution of Ca2+ release. TEVC was performed with micropipette containing chelerythrine to prevent PKC dependent run-up or run-down. Under these conditions, Ca2+-activated Cl- currents induced by bath application of Ca2+ to oocytes showed stable peak amplitude when repetitively activated, allowing us to test several concentrations of a test compound from one oocyte. Inhibitory activities of commercially available blockers and
To gain insight into the mechanisms involved in the formation of maternally stored mRNPs during Xenopus laevis development, we searched for soluble cytoplasmic proteins of the oocyte that are able to selectively bind mRNAs, using as substrate radiolabeled mRNA. In vitro mRNP assembly in solution was followed by UV-cross-linking and RNase digestion, resulting in covalent tagging of polypeptides by nucleotide transfer. Five polypeptides of approximately 54, 56 60, 70, and 100 kD (p54, p56, p60, p70, and p100) have been found to selectively bind mRNA and assemble into mRNPs. These polypeptides, which correspond to previously described native mRNP components, occur in three different particle classes of approximately 4.5S, approximately 6S, and approximately 15S, as also determined by their reactions with antibodies against p54 and p56. Whereas the approximately 4.5S class contains p42, p60, and p70, probably each in the form of individual molecules or small complexes, the approximately 6S particles ...
In our laboratory, we use Xenopus laevis, commonly known as the African clawed frog (learn more on wikipedia). Xenopus laevis is a great model system for dissecting the molecular pathways in DNA replication and the maintenance of genomic stability. Cell-free extracts made from Xenopus eggs contain all the proteins necessary to undergo 12 rounds of cell-cycle regulated, semi-conservative DNA replication in the absence of transcription. Events in these extracts are highly synchronous, allowing the analysis of short-lived intermediates and the dissection of signal transduction cascades. Particularly, the function of essential proteins can be addressed by immunodepletion or neutralization of these proteins, coupled to rescue with recombinant proteins. Xenopus cell-free extracts are generated by centrifuging unfertilized Xenopus eggs and isolating the cytoplasmic layer. Female Xenopus can be induced to lay an abundance of eggs after hormone injection. In fact, Xenopus laevis were used as a pregnancy ...
In vivo tracking of histone H3 lysine 9 acetylation in Xenopus laevis during tail regenerationIn vivo tracking of histone H3 lysine 9 acetylation in Xenopus laevis during tail regeneration ...
Poly (A) binding proteins are intimately implicated in controlling a number of events in mRNA metabolism from nuclear polyadenylation to cytoplasmic translation and stability. The known poly(A) binding proteins can be divided into three distinct structural groups (prototypes PABP1, PABPN1/PABP2 and Nab2p) and two functional families, showing that similar functions can be accomplished by differing structural units. This has prompted us to perform a screen for novel poly(A) binding proteins using Xenopus laevis. A novel poly(A) binding protein of 32 kDa (p32) was identified. Sequence analysis showed that p32 has about 50% identity to the known nuclear poly(A) binding proteins (PABPN1) but is more closely related to a group of mammalian proteins of unknown function. The expression of Xenopus laevis ePABP2 is restricted to early embryos. Accordingly, we propose that p32 is the founder member of a novel class of poly(A) binding proteins named ePABP2.
BioAssay record AID 630202 submitted by ChEMBL: Inhibition of retinal rod CNGA1/CNGB1 expressed in Xenopus laevis oocytes assessed as blockade of cGMP-induced current at +50 mV holding potential by patch-clamp electrophysiology.
We have examined the timing of specification of the pronephric tubules and duct in Xenopus laevis by explanting the presumptive pronephric rudiments into blastula ectodermal wraps. We have established I-he time point of specification using the monoclonal antibody markers 3G8 and 4A6 which recognize antigens in pronephric tubule and duct, respectively. We show that, by experimental analysis in explants, kidney tubules are specified by stage 12.5 in the pronephric anlagen whereas pronephric duct is specified later between stages 13 and 14. Furthermore we show that signals involved in tubulogenesis of the pronephric tubules are normally received between stage 12.5 and 13. These experiments unambiguously pinpoint the timing of pronephros specification analyzed by explant experimentation to a developmental stage prior to that demonstrated for urodele amphibia, and provide an essential biological backdrop to a search for the molecular nature of pronephric inducers. (C) 1998 Elsevier Science Ireland ...
Selective modulation of α7 nicotinic acetylcholine receptors (nAChRs) is thought to regulate processes impaired in schizophrenia, Alzheimers disease, and other dementias. One approach to target α7 nAChRs is by positive allosteric modulation. Structurally diverse compounds, including PNU-120596, 4-naphthalene-1-yl-3a,4,5,9b-tetrahydro-3-H-cyclopenta[c]quinoline-8-sulfonic acid amide (TQS), and 5-hydroxyindole (5-HI) have been identified as positive allosteric modulators (PAMs), but their receptor interactions and pharmacological profiles remain to be fully elucidated. In this study, we investigated interactions of these compounds at human α7 nAChRs, expressed in Xenopus laevis oocytes, along with genistein, a tyrosine kinase inhibitor. Genistein was found to function as a PAM. Two types of PAM profiles were observed. 5-HI and genistein predominantly affected the apparent peak current (type I) whereas PNU-120596 and TQS increased the apparent peak current and evoked a distinct weakly decaying ...
This study analyzes the expression and the function of Xenopus msx-1 (Xmsx-1) in embryos, in relation to the ventralizing activity of bone morphogenetic protein-4 (BMP-4). Expression of Xmsx-1 was increased in UV-treated ventralized embryos and decreased in LiCl-treated dorsalized embryos at the neurula stage (stage 14). Whole-mount in situ hybridization analysis showed that Xmsx-1 is expressed in marginal zone and animal pole areas, laterally and ventrally, but not dorsally, at mid-gastrula (stage 11) and late-gastrula (stage 13) stages. Injection of BMP-4 RNA, but not activin RNA, induced Xmsx-1 expression in the dorsal marginal zone at the early gastrula stage (stage 10+), and introduction of a dominant negative form of BMP-4 receptor RNA suppressed Xmsx-1 expression in animal cap and ventral marginal zone explants at stage 14. Thus, Xmsx-1 is a target gene specifically regulated by BMP-4 signaling. Embryos injected with Xmsx-1 RNA in dorsal blastomeres at the 4-cell stage exhibited a ...
Kv1.5 channel blockers prolong atrial action potentials and may prevent atrial flutter or fibrillation without affecting ventricular repolarization. Here we characterize the mechanisms of action of 2′-{[2-(4-methoxy-phenyl)-acetylamino]-methyl}-biphenyl-2-carboxylic acid (2-pyridin-3-yl-ethyl)-amide (AVE0118) on Kv1.5 channels heterologously expressed in Xenopus laevis oocytes. Whole cell currents in oocytes were recorded using the two-microelectrode voltage clamp technique. AVE0118 blocked Kv1.5 current in oocytes with an IC50 of 5.6 μM. Block was enhanced by higher rates of stimulation, consistent with preferential binding of the drug to the open state of the channel. Ala-scanning mutagenesis of the pore domain of Kv1.5 identified the amino acids Thr479, Thr480, Val505, Ile508, Val512, and Val516 as important residues for block by AVE0118. A homology model of the pore region of Kv1.5 predicts that these six residues face toward the central cavity of the channel. In addition, mutation of two ...
Freeze fracture replica of zonula occludens junctions from the small intestine of a Xenopus laevis tadpole. The occluding junction appears as a mesh...
Freeze fracture replica of zonula occludens junctions from the small intestine of a Xenopus laevis tadpole. The occluding junction appears as a mesh...
The development of serotonin-immunoreactive neurons in the central nervous system of Xenopus laevis larvae has been studied with special emphasis on the development of the raphe nuclei and raphespinal projections. The first serotonergic neurons were observed in the rostral part of the brain stem at …
Delineation of apical and basolateral membrane domains is a critical step in the epithelialization of the outer layer of cells in the embryo. We have examined the initiation of polarized membrane traffic in Xenopus and show that membrane traffic is not polarized in oocytes but polarized membrane domains appear at first cleavage. The following proteins encoded by injected RNA transcripts were used as markers to monitor membrane traffic: (a) VSV G, a transmembrane glycoprotein preferentially inserted into the basolateral surface of polarized epithelial cells; (b) GThy-1, a fusion protein of VSV G and Thy-1 that is localized to the apical domains of polarized epithelial cells; and (c) prolactin, a peptide hormone that is not polarly secreted. In immature oocytes, there is no polarity in the expression of VSV G or GThy-1, as shown by the constitutive expression of both proteins at the surface in the animal and vegetal hemispheres. At meiotic maturation, membrane traffic to the surface is blocked; ...
This image is part of a large data set of Xenopus laevis eggs imaged at various times post fertilization (the first number of the file name correspond...
Results were expressed as amplitude of peak cur rents evoked by ,meATP or as current density, defined as the ratio of peak amplitude over membrane capacitance. For measuring recovery, the amplitude of the third P2X3 response was compared to the first and expressed as a percentage. they The results obtained after 2 h drug incubation Inhibitors,Modulators,Libraries were always compared to those obtained after 2 h incubation in culturing media containing DMSO. Membrane capacitance and series resistance were measured through the peak amplitude and decay constant of transients induced by repetitive depolarizing pulses of 10 mV. Voltage clamp and macropatch recordings in Xenopus oocytes Oocytes were surgically removed from Tricaine anesthe tized female Xenopus laevis frogs and were incubated in OR2 solution containing 1 2 mgml type IA collagenase at room temperature for 2 h under agitation.. Stage V and VI oocytes were then manually defolliculated before nuclear or cytoplasmic microinjection of ...
Xenopus Xlrbpa protein: Xenopus laevis homolog of human TAR-RNA-binding protein; MW 33 kDa; amino acid sequence in first source; GenBank M96370
Cloning of Xenopus laevis nuclear poly(A)-rich RNA sequences. Evidence for post-transcriptional control.: cDNA/RNA hybridization experiments of polysomal and nu
Neurogenesis is required for behavioral recovery after injury in the visual system of Xenopus laevis. by Caroline R McKeown, Pranav Sharma, Heidi E Sharipov, Wanhua Shen, Hollis T Cline. The Journal of comparative neurology. Read more related scholarly scientific articles and abstracts.
The ultrastructure of the glomus cells of the carotid labyrinth was investigated in the anuran, Xenopus laevis. These cells show many catecholamine containing granules. About 50 cells in groups of 3-5 are located near the sinusoids. Morphologically,
Compare Anti-eomesodermin homolog (Xenopus laevis) Antibody Products from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more.
Domain architecture and assignment details (superfamily, family, region, evalue) for gi|139635|sp|P19009| from Xenopus laevis . Plus protein sequence and external database links.
Xenopus laevis is one of the best ectothermic vertebrate models for studying the phylogeny and ontogeny of the immune system. The evolutionary distance of X. la...
Recombinant Prkr Interacting Protein 1 (IL11 Inducible) (PRKRIP1) Protein (His tag). Species: Xenopus laevis. Source: Yeast. Order product ABIN1674163.
Population-specific incidence of testicular ovarian follicles in Xenopus laevis from South Africa : A potential issue in endocrine ...
TY - JOUR. T1 - Characterization of glutamate receptors induced in Xenopus oocytes after injection of rat brain mRNA. AU - Hirono, Chikara. AU - Ito, Isao. AU - Yamagishi, Shunichi. AU - Sugiyama, Hiroyuki. PY - 1988/12. Y1 - 1988/12. N2 - Xenopus oocytes in which poly(A)+ mRNA isolated from rat brains were previously injected, exhibited at least 3 categories of current responses to excitatory amino acids. They were oscillatory responses to glutamate (Glu) or quisqualate (QA), smooth large responses to kainate (KA), and smooth small responses to Glu and QA. Oscillatory responses were mediated by a metabotropic type of Glu receptor which is coupled to a G-protein but not directly to an ionic channel. Amplitudes of smooth Glu responses and smooth QA responses were similar in size, and were not additive to each other, suggesting a common receptor mediating both responses. l-Glutamylglycine inhibited KA responses in a competitive manner without affecting smooth Glu/QA responses, indicating that KA ...
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Exhibits mesoderm-dorsalizing activity and neural-inducing activity, but lacks mesoderm-inducing activity. Regulates the expression of specific mesodermal and neural genes. Induces convergent extension movements at the embryonic midline by activating the fgf signaling pathway to induce t/bra expression in the organizer region. Acts with wnt11 to induce Spemann organizer cells and induce axis formation. The unprocessed protein antagonizes bmp-signaling. [-] ...
Xenopus laevis is an essential model organism in several areas of biology. In addition to the key attributes of these embryos for in vivo imaging, cell-free extracts from Xenopus provide among the most powerful in vitro systems for studies of cell and molecular biology. A complete sequence of the X. laevis genome is an essential resource for accurate identification of peptides for mass-spec analyses, for cloning of an ORFeome, for identifying evolutionarily conserved regulatory regions, and for design of morpholino-oligonucleotides for gene knockdowns. The Wallingford and Marcotte labs have obtained funding from the Texas Institute for Drug and Diagnostic Development (TI3D), in coordination with projects funded by the National Institutes of Health, to begin sequencing of the X. laevis genome. We are primarily working with Scott Hunicke-Smith at the University of Texas Genome Sequencing and Analysis facility, with funding sufficient for ~20x coverage of the X. laevis genome using ABI SOLiD ...
Xenopus laevis is an essential model organism in several areas of biology. In addition to the key attributes of these embryos for in vivo imaging, cell-free extracts from Xenopus provide among the most powerful in vitro systems for studies of cell and molecular biology. A complete sequence of the X. laevis genome is an essential resource for accurate identification of peptides for mass-spec analyses, for cloning of an ORFeome, for identifying evolutionarily conserved regulatory regions, and for design of morpholino-oligonucleotides for gene knockdowns. The Wallingford and Marcotte labs obtained funding from the Texas Institute for Drug and Diagnostic Development (TI3D), in conjunction with projects funded by the National Institutes of Health, to begin sequencing of the X. laevis genome. We began the project with Scott Hunicke-Smith at the University of Texas Genome Sequencing and Analysis facility, with funding sufficient for ~20x coverage of the X. laevis genome using ABI SOLiD next-generation ...
The molecular mechanisms by which PCBs induce their toxicity during the development of tadpoles remain largely unknown. The present study is the first to investigate the potential effects of relevant environmental concentrations of these pollutants on the protein expression profiles of developing X. laevis tadpoles.. PCBs are known to affect the survival of numerous species, including amphibians. In the present study, the exposure of 5-day pf X. laevis tadpoles to 0.1 and 1 ppm Aroclor 1254 for 72 h did not impair their survival. This observation is in agreement with the data of Fisher et al. (11) that established that the survival of 9-day pf X. laevis tadpoles was not affected by the exposure to 1 ppm Aroclor 1254. The same observation was made on 7-day pf X. laevis tadpoles (10). However, another study conducted on X. laevis highlighted that 18-day pf tadpole exposed to 0.7 ppm Aroclor 1254 for 48 h showed a survival rate around 55% (32). Moreover the incidence of mortality was 10 times ...
The image features the head of the tadpole of the African clawed frog, Xenopus laevis, from the Ai-Sun Tseng lab in the School of Life Sciences. Our image highlights the complexity of the tadpole. The tadpole is mostly transparent that it enables the use of color to highlight key tissues to study tissue regeneration. We can label tissues with specific markers that glow in different colors to show how each part of the tadpole interacts with each other. The muscles are shown in red and a protein is in green. This allows us to work towards understanding how some animals, such as the frog tadpole, can regenerate body parts, but others are cannot. This is an important question in medicine because it can help us understand the ways in which some animals repair their body parts and apply this towards creating novel therapies to improve tissue repair in humans.
Membrane potential and resistance were measured in eggs, cleavage stages and blastulae of the South African toad Xenopus laevis, using intracellular microelectrodes.. The membrane potential increased from −6·5 ± 2mV in eggs to −57 ± 8·0mV at the mid-blastula stage.. The input resistance of fertile eggs ranged from 0·5 MΩ to 5·0 MΩ corresponding to a specific resistance of 20-200kΩcm2. During the first two or three division cycles the input resistance usually decreased by a factor of 2-10 and then subsequently rose during the blastula stages from a mean value of 600 ± 100kΩ at stage 5 to 2·0 ± 0·5 MΩ at stage 8.. At all developmental stages examined, point polarization of a surface cell in the embryo by rectangular current pulses of 0·5−6 × 10−8 A produced voltage deflexions in other surface cells. This was seen even when several (7-8) cell junctions intervened between the current passing and voltage recording microelectrodes at distances of more than 1 mm. These ...
TY - JOUR. T1 - Presenilin 1 mutations increase amyloid precursor protein production and proteolysis in Xenopus laevis oocytes. AU - Heyn, Sietske N.. AU - Vulliet, Philip R. PY - 2001/6/22. Y1 - 2001/6/22. N2 - Recent findings suggest that Presenilin 1 (PS1) mutations play a major role in the development of Alzheimers disease (AD) by increasing the production of the beta amyloid peptide (Aβ). The exact mechanism whereby mutations in PS1 lead to this effect is not clear. To examine the question of how PS1 might be involved in amyloid precursor protein (APP) processing, we constructed a chimera of human APP695 fused at the C-terminal to enhanced green fluorescent protein (EGFP). This construct was injected into Xenopus laevis oocytes in the presence of wild type PS1 or one of three PS1 mutations associated with AD. The cellular location of the APP695-EGFP construct was examined by fluorescent confocal microscopy. In addition, membrane fractions of oocytes expressing APP695-EGFP in the presence ...
Directional cell migration is an intensively studied process relevant for both normal development of an organism as well as for a number of pathological conditions such as chronic inflammation and cancer. Primordial germ cells (PGCs) in Xenopus laevis embryos can be used as a model system to study cell migration, since during embryogenesis they actively migrate within the endoderm towards genital ridges. Transition to active cell migration is a highly regulated process important for the normal PGC development in many species. This study is focused on molecular and cellular mechanisms involved in initiation of active PGC migration within the endoderm of X. laevis embryos. Analysis of cell shape fluctuations demonstrated that in comparison to pre-migratory neural stage, PGCs isolated from tailbud stage embryos are characterized by an increased cellular dynamics due to formation of bleb-like protrusions and migration via bleb-associated mechanism. Analysis of intracellular PIP3 distribution that ...
The genetic lesion diagnostic for facioscapulohumeral muscular dystrophy (FSHD) results in an epigenetic misregulation of gene expression, which in turn is what ultimately leads to the disease pathology. FRG1 (FSHD region gene 1) is a leading candidate gene whose misexpression may lead to FSHD. As FSHD pathology is most prominent in the musculature, most research and therapy efforts have focused on muscle cells. However, between 50-75% of FSHD patients also exhibit retinal vasculopathy and FSHD muscle has increased levels of vascular-endothelial related transcripts, suggesting an underappreciated vascular component to the disease. Using Xenopus laevis as a model, we have shown a previously unsuspected role for FRG1 in the development of both muscular and vascular structures. Furthermore, overexpression of frg1 displays disrupted muscle and dilated and tortuous vessels, phenocopying the symptoms of FSHD patients. Thus, our work strongly supports a role for FRG1 in FSHD disease pathology ...
TY - JOUR. T1 - Quantum Nanobiology and Biophysical Chemistry. A2 - Jalkanen, Karl J.. A2 - Jensen, Gerard Michael PY - 2013. Y1 - 2013. N2 - An introduction was provided in the first issue by way of an Editorial to this special two issue volume of Current Physical Chemistry - Quantum Nanobiology and Biophysical Chemistry [1]. The Guest Editors would like to thank all the authors and referees who have contributed to this second issue. Boulos et al. look at gold nanorods in a biological setting. Kneipp and Kneipp look at the impact of silver nanoparticle interactions with biomolecules using Raman optical activity. Johannessen and Blanch provide a review of recent developments in Raman optical activity calculations of biomolecules. Masuda et al. study Raman markers in the xenopus laevis oocyte expression system. Marsi et al. explore the cytocompatibility of carbon nanotubes across the hydrophilicity spectrum. Ahmed and Wang explore detailed structural aspects of didehydro-deoxycytidine drugs and ...
The present investigation evaluates the toxic potential of Cd in larvae of the frog Xenopus laevis after 12 days of exposure to environmentally relevant contamination levels, close to those measured in the river Lot (France). Several genotoxic and detoxification mechanisms were analyzed in the larvae: clastogenic and/or aneugenic effects in the circulating blood by micronucleus (MN) induction, metallothionein (MT) production in whole larvae, gene analyses and Cd content in the liver and also in the whole larvae. The results show: (i) micronucleus induction at environmental levels of Cd contamination (2, 10, 30 μg L−1); (ii) an increased and concentration-dependent quantity of MT in the whole organism after contamination with 10 and 30 μg Cd L−1 (a three- and six-fold increase, respectively) although no significant difference was observed after contamination with 2 μg Cd L−1; (iii) Cd uptake by the whole organism and by the liver as a response to Cd exposure conditions; (4) up-regulation ...
The caudal-related (Cdx) homeodomain transcription factors have a conserved role in the development of posterior structures in both vertebrates and invertebrates. A particularly interesting finding is that Cdx proteins have an important function in the regulation of expression from a subset of Hox genes. In this study, we report the cloning of cDNAs from the Cdx genes of the amphibian Xenopus tropicalis. Xenopus tropicalis is a diploid species, related to the commonly used laboratory animal Xenopus laevis, and has attracted attention recently as a potential genetic model for animal development. The Xenopus tropicalis cDNAs, Xtcad1, Xtcad2, and Xtcad3, show between 88 and 94% sequence identity with their Xenopus laevis orthologues. This finding corresponds to between 90 and 95% identity at the level of derived amino acid sequence. We also present a detailed description of Xtcad1, Xtcad2, and Xtcad3 expression during normal development. In common with the Cdx genes of other vertebrates, the ...
TY - JOUR. T1 - Cell behaviors associated with somite segmentation and rotation in Xenopus laevis. AU - Afonin, Bonnie. AU - Ho, Minh. AU - Gustin, Jean K.. AU - Meloty-Kapella, Caroline. AU - Domingo, Carmen R.. PY - 2006/12/1. Y1 - 2006/12/1. N2 - During vertebrate development the formation of somites is a critical step, as these structures will give rise to the vertebrae, muscle, and dermis. In Xenopus laevis, somitogenesis consists of the partitioning of the presomitic mesoderm into somites, which undergo a 90-degree rotation to become aligned parallel to the notochord. Using a membrane-targeted green fluorescent protein to visualize cell outlines, we examined the individual cell shape changes occurring during somitogenesis. We show that this process is the result of specific, coordinated cell behaviors beginning with the mediolateral elongation of cells in the anterior presomitic mesoderm and then the subsequent bending of these elongated cells to become oriented parallel with the ...
Cryogenic 4303 (MCZ:Cryo:4303); Xenopus laevis; Africa: South Africa: Western Cape; Forestry office 4 km from Garden Route National Park; Animalia Chordata Amphibia Lissamphibia Anura Pipoidea Pipidae Xenopus laevis; African clawed frog; Clawed toad; Common clawed frog; Common clawed toad; Common platanna; platanna
Cryogenic 4317 (MCZ:Cryo:4317); Xenopus laevis; Africa: South Africa: Northern Cape; Approx. 30 km south of Kimberley, Debonaire Farm; Animalia Chordata Amphibia Lissamphibia Anura Pipoidea Pipidae Xenopus laevis; African clawed frog; Clawed toad; Common clawed frog; Common clawed toad; Common platanna; platanna
Xenopus laevis, the African clawed frog, is commonly used in developmental and toxicology research studies. Little information is available on aged X. laevis; however, with the complete mapping of the genome and the availability of transgenic animal models, the number of aged animals in research colonies is increasing. The goals of this study were to obtain biochemical and hematologic parameters to establish reference intervals for aged X. laevis and to compare results with those from young adult X. laevis. Blood samples were collected from laboratory reared, female frogs (n = 52) between the ages of 10 and 14 y. Reference intervals were generated for 30 biochemistry analytes and full hematologic analysis; these data were compared with prior results for young X. laevis from the same vendor. Parameters that were significantly higher in aged compared with young frogs included calcium, calcium:phosphorus ratio, total protein, albumin, HDL, amylase, potassium, CO2, and uric acid. Parameters found to ...
A direct test was made of predictions of the double-strand-break repair (DSBR) model of recombination in Xenopus laevis oocytes. The DNA substrate injected into oocytes had two directly repeated copies of a 1.25-kb sequence and was cleaved within one of them. Different products were expected to result from concerted, conservative events, as predicted by the DSBR model, and from nonconservative events. Only very low levels of recombination products, both conservative and nonconservative, were observed. When individual, apparent DSBR products were cloned and characterized, it emerged that the majority of them had arisen by nonconservative recombination through short, terminal homologies and not from the gene conversion events predicted for DSBR. Two cloned products among 44 tested corresponded to the predications of the DSBR model, but these could also have been generated by other processes. The most efficient recombination events in oocytes are nonconservative and are based on long, terminal ...
Two main chromatin assembly pathways ensure the proper transmission of chromatin organization and chromatin-based information throughout the cell cycle. A replication-dependent (RD) pathway that couples chromatin assembly to DNA synthesis and a replication-independent (RI) pathway. Whether these pathways contribute to the establishment of chromatin domains like heterochromatin or euchromatin by introducing modifications on histones or modulating chromatin structure remains unknown. Using Xenopus laevis egg extracts we monitored RD and RI chromatin assembly on single-stranded and double-stranded DNA templates. Even though RD assembly proceeded faster than RI assembly the histone content and saturation level with nucleosomes were similar. Despite these comparable topological features, the hydrodynamic behavior of both chromatin species in sucrose gradient centrifugation clearly differed. The RD assembled chromatin ran at lower sucrose concentrations than the RI created chromatin suggesting ...
The African clawed frogs Xenopus laevis and Xenopus tropicalis are prominent animal model organisms. Xenopus research contributes to the understanding of genetic, developmental and molecular mechanisms underlying human disease. The Xenopus Anatomy Ontology (XAO) reflects the anatomy and embryological development of Xenopus. The XAO provides consistent terminology that can be applied to anatomical feature descriptions along with a set of relationships that indicate how each anatomical entity is related to others in the embryo, tadpole, or adult frog. The XAO is integral to the functionality of Xenbase ( http://www.xenbase.org ), the Xenopus model organism database. We significantly expanded the XAO in the last five years by adding 612 anatomical terms, 2934 relationships between them, 640 synonyms, and 547 ontology cross-references. Each term now has a definition, so database users and curators can be certain they are selecting the correct term
These systems are designed for two-electrode, whole-cell voltage clamping of large cells such as Xenopus oocytes and cell structures such as squid axons. They are either bundled with an Oocyte Clamp Amplifier or a more comprehensive Two Electrode Voltage Clamp Workstation, which provide clamping and amplification of measured signals from glass microelectrodes/sharp electrodes.
The frog genus Xenopus is widely used as a model system for studying developmental biology and fundamental cell biological processes. The advantages that Xenopus offer as an experimental system include (1) the availability of large abundant eggs that are easily manipulated, (2) ready accessibility to any developmental stage, and (3) conservation of cellular pathways between Xenopus and mammals. Over the past 50 years, pioneering studies on Xenopus have been crucial towards our understanding of nuclear reprogramming, embryonic patterning, membrane channels and receptors, and the cell cycle.. Despite its popularity for biomedical research, genomic resources for Xenopus have been lagging behind other model organisms. A major reason for this is that early developmental and molecular studies have relied on a particular species known as Xenopus laevis, which is pseudotetraploid as a result of genome duplication around 30 million years ago. The presence of four copies of every gene complicates genetic ...
In this work, we report an efficient method to easily study transmitter receptors originally assembled in cultured cell lines and then microtransplanted to a sturdy and convenient host cell system, the Xenopus oocyte. This method has been recently used to transplant assembled transmitter receptors from human brain to Xenopus oocyte (7), following a method developed a few years ago to microtransplant AcChoRs and chloride channels from the electric organ of Torpedo to the Xenopus oocyte membrane (5, 6). Here, we injected membrane vesicles prepared from cultured cell lines, and this approach led to a rapid incorporation of neurotransmitter receptors in the oocyte plasma membrane. In this way, functional AMPA-type GluR1, α7-AcChoRs, and α4β2-AcChoRs from cultured cells were microtransplanted to the oocytes, and their respective transmitter-activated currents were analyzed.. We report here that the gross electrophysiological and pharmacological characteristics of the transmitter-gated receptors ...
The experiments described in this paper were designed to compare the normal fates of animal pole blastomeres of Xenopus laevis with their state of commitment. Single animal pole blastomeres were labeled with a lineage marker and transplanted into the blastocoels of host embryos of different stages. …
The first 12 cell divisions of Xenopus laevis embryos do not require gene transcription. This means that the regulation of gene expression during this period is controlled at post transcriptional levels and makes Xenopus early development a potentially interesting biological system with which to study the mechanisms involved. We describe here the stability characteristics of several maternal Xenopus mRNAs which are deadenylated soon after fertilisation (J. Paris and M. Philippe, Dev. Biol., in press). We show that these mRNAs were only degraded in the embryo after the midblastula transition (MBT), when gene transcription was initiated. The kinetics with which the deadenylated maternal mRNAs decreased in the post-MBT embryos showed sequence specificity. The degradation of these mRNAs after the MBT was inhibited by cycloheximide but was not affected by dactinomycin. Therefore, the destabilization of these mRNAs does not appear to be initiated by new embryonic gene transcripts. Sequence comparisons ...
In this study, we focused on the pharmacological characterization of cannabinoid receptor coupling to G protein-gated inwardly rectifying potassium (GIRK) channels. Cannabinoids were tested on Xenopus laevis oocytes coexpressing the CB1 receptor and GIRK1 and GIRK4 channels (CB1/GIRK1/4) or the CB2 receptor and GIRK1/4 channels (CB2/GIRK1/4). WIN 55,212-2 enhanced currents carried by GIRK channels in the CB1/GIRK1/4 and CB2/GIRK1/4 system; however, the CB2 receptor did not couple efficiently to GIRK1/4 channels. In the CB1/GIRK1/4 system, WIN 55,212-2 was the most efficacious compound tested. CP 55,940 and anandamide acted as partial agonists. The rank order of potency was CP 55,940 , WIN 55,212-2 = anandamide. The CB1-selective antagonist SR141716A alone acted as a inverse agonist by inhibiting GIRK currents in oocytes expressing CB1/GIRK1/4, suggesting the CB1receptor is constitutively activated. A conserved aspartate residue, which was previously shown to be critical for G protein coupling in ...
Descrição: Using glutathione affinity chromatography followed by isoelectrofocusing, we purified from the skin secretion of Xenopus laevis an isoenzyme of glutathione S-transferase with an apparent subunit molecular mass of 22.5 kDa and an isoelectric point at pH 5.1. Its N-terminal amino acid sequence was highly similar to that of the sigma class glutathione S-transferase, which previously was demonstrated to have a glutathione-dependent prostaglandin D2 synthase activity. Immunohistochemistry analysis revealed that the isoenzyme was located in the cytoplasm of granular gland cells. ...
The vertebrate Otx gene family is related to otd, a gene contributing to head development in Drosophila. We previously reported on the expression of Xotx2 gene, homologous to the murine Otx2 gene, during early Xenopus development. In the present paper we report an extensive analysis of the expression pattern of Xotx2 during later stages of development and also the cloning and developmental expression of two additional Otx Xenopus genes, Xotx1 and Xotx4. These latter two genes bear a good degree of homology to murine Otx1, higher for Xotx1 than for Xorx4. Both these genes are expressed in the forebrain and midbrain regions and their developmental patterns of expression are very similar, although not perfectly superimposable. Spatial and temporal expression patterns of the three Xotx genes suggest that they may be involved in the early subdivision of the rostral brain, providing antero-posterior positional information within the most anterior districts of the neuraxis. The three Xotx genes are ...
Descrição: Using glutathione affinity chromatography followed by isoelectro‐focusing, we purified from the skin secretion of Xenopus laevis an isoenzyme of glutathione S‐transferase with an apparent subunit molecular mass of 22.5 kDa and an isoelectric point at pH 5.1. Its N‐terminal amino acid sequence was highly similar to that of the sigma class glutathione S‐transferase, which previously was demonstrated to have a glutathione‐dependent prostaglandin D2 synthase activity. Immunohistochemistry analysis revealed that the isoenzyme was located in the cytoplasm of granular gland cells. ...
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Dissertation example: RPA - and RPA/Ku-little bodies in the kernels generated in system in vitro Xenopus laevis - Histology, cytology, cellular biology - Biological sciences
We have moved to other location and our principal breeding facility will be closed in October. All animals, including breeding pairs of Silurana tropicalis, adult males of Silurana tropicalis, adult Xenopus laevis, albino Xenopus laevis and the whole breeding colony of Xenopus amieti are for ...
Brown, Bethany - Extraction of total RNA from Mus musculus and Peromyscus maniculataus tissues for validation of the microarray system (Mentor: Eric Bradley, Biology) Carra, Bradley - cDNA Library Screening for the Glutamate Transport Protein (Mentor: Margaret Saha,Biology) Cox, Elizabeth - Development of Fluorescent Probes for X1-Flkand Xl-Fli for Use in Expression Studies in Xenopus laevis (Mentor: Margaret Saha, Biology) DeCuir, Jennifer - Isolation of the Promoter Region of the GAD Gene (Mentor: Margaret Saha,Biology) Doerries, Mark - Community Structure in Mussel Beds at Logatchev, A Deep-Sea Hydrothermal Vent on the Mid-Atlantic Ridge (Mentor: Cindy VanDover,Biology) Dondeti, Vijay - Glutamate Transporter Promoter Analysis in Xenopulaevis (Mentor: Margaret Saha,Biology) Evans, Jessica - Expression and Determination of the Glutamate and GABA Transporters in the Presynaptic Axon Terminal of the Neuron in Xenopus laevis Cell Culture (Mentor: Margaret Saha,Biology) Fink, Erin - Altered Nuclear ...
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Polarity is a salient feature of oocytes. Consider, for example, the yolk-rich amphibian oocyte. As we shall discuss later, not only are organelles localized in the egg, but macromolecules may also have specific domains.. (See Browder et al., Fig. 3.11). As with sperm, mitochondria are significant oocyte organelles. They may be present in great abundance to fuel the events of early development, during which the embryo has no facility to produce new mitochondria of its own. (Remember that mitochondria are self-replicating.). An example is the amphibian Xenopus laevis. In somatic cells, the ratio of nuclear DNA:mitochondrial DNA is 100:1. In the fully-grown oocyte, that ratio has reversed to a range from 1:1 to 1:100. During mitochondrial replication in early oogenesis, mitochondria cluster around the nucleus to form a structure called the mitochondrial cloud.. (See Browder et al., Fig. 3.12) The cloud also contain electron-dense material called granulofibrillar material (GFM). The mitochondrial ...
Voltage-gated Na(+) channels (Na(+) channels) mediate the rising phase of action potentials in neurons and excitable cells. Nine subtypes of the alpha subunit (Na(v)1.1-Na(v)1.9) have been shown to form functional Na(+) channels to date. Recently, anesthetic concentrations of volatile anesthetics and ethanol were reported to inhibit Na(+) channel functions, but it is not known whether all subtypes are inhibited by anesthetics. To investigate possible subtype-specific effects of anesthetics on Na(+) channels, mRNA of Na(v)1.2, Na(v)1.4, Na(v)1.6, and Na(v)1.8 alpha subunit-encoded genes were injected individually or together with a beta subunit mRNA into Xenopus oocytes. Na(+) currents were recorded using the two-electrode voltage-clamp technique. Isoflurane, at clinically relevant concentrations, inhibited the currents produced by Na(v)1.2, Na(v)1.4, and Na(v)1.6 by approximately 10% at the holding potential of -90 mV and by approximately 30% at -60 mV, but it did not affect the Na(v)1.8-mediated
Poly(A)+ messenger RNA (mRNA) extracted from rat brains or from cat muscles was injected into Xenopus laevis oocytes. This led to the incorporation of voltage-operated Na+ and K+ channels into the oocyte membrane. These channels are not normally present in the oocyte and presumably result from the synthesis and processing of proteins coded by the injected mRNA. Tetrodotoxin blocked the Na+ channels induced by mRNA derived from either innervated or denervated muscle. ...
The goal of this laboratory course is to introduce vertebrate developmental biology to undergraduate students, emphasizing both classical and contemporary aspects of this field. During the course, the students combine the use of living Xenopus laevis material with active tutorial participation, with the aim of illustrating how the fertilized egg can generate the diversity of cell types and complexity of pattern seen only a few days later in the embryo. Special emphasis is given to the observation and manipulation of living material. The laboratory course includes a comprehensive analysis of both oogenesis and early development and is divided into two overlapping parts that combine tutorial and practical approaches. The first part is devoted to oogenesis; oocytes are sorted out, allowed to mature in vitro and observed in histological section. In the second part, students perform an in vitro fertilization of Xenopus eggs and a mesoderm and neural induction assay of animal cap explants. Successful
Background: Peptide transporter 1 (PepT1, alias Slc15a1) mediates the uptake of dietary di/tripeptides in all vertebrates. However, in teleost fish, more than one PepT1-type transporter might function, due to specific whole ...
The present study examined the influence of endocrine active compounds (endocrine disruptors, ED), which are present in surface waters, on reproductive biology of aquatic organisms. The amphibian Xenopus laevis is a well-established model organism for the study of effects of ED on reproduction. It has been modified and broadened for the purpose of this study, and it was combined with chemical methods for water analyses. It is possible to assess water pollution with ED by detecting effects on repro-ductive biology of one particular substance, and then by looking for this substance in environmental water samples. We showed the feminizing potency of Bisphenol A (BPA) in conducting exposure experiments with tadpoles, in examining histological samples of gonads and in detecting the induction of the expression of a molecular estrogenic biomarker. BPA was recognized to mediate its effects via binding to the estrogen receptor. Moreover, analysis of BPA during exposure experiments revealed that BPA is ...
SUMMARYFactors affecting survival of parasites introduced to new geographical regions include changes in environmental temperature. Protopolystoma xenopodis is a monogenean introduced with the amphibian Xenopus laevis from South Africa to Wales (probably in the 1960s) where low water temperatures impose major constraints on life-cycle processes. Effects were quantified by maintenance of eggs from infections in Wales under controlled conditions at 10, 12, 15, 18, 20 and 25°C. The threshold for egg viability/ development was 15°C. Mean times to hatching were 22 days at 25°C, 32 days at 20°C, extending to 66 days at 15°C. Field temperature records provided calibration of transmission schedules. Although egg production continues year-round, all eggs produced during ,8 months/ year die without hatching. Output contributing significantly to transmission is restricted to 10 weeks (May-mid-July). Host infection, beginning after a time lag of 8 weeks for egg development, is also restricted to 10 ...
Frog Forum - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
... - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
... - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
Frog Forum - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
Frog Forum - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
Frog Forum - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc
Frog Forum - Your Pet Frog Community. Authoritative discussion forum for pet frogs and toads, including dart frogs, tree frogs, bullfrogs, toads, etc

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