Xenopus laevis: 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.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.Xenopus Proteins: 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.Oocytes: 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).Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.Metamorphosis, Biological: 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.Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.Molecular Sequence Data: 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.Gastrula: 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.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Amino Acid Sequence: 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.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Gene Expression Regulation, Developmental: 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.Cloning, Molecular: 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.Vitellogenins: 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, Messenger: 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.Blastula: 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.RNA, Complementary: 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)In Situ Hybridization: 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.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Embryonic Induction: 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).Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.Ectoderm: The outer of the three germ layers of an embryo.Oogenesis: The process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).Cell Extracts: Preparations of cell constituents or subcellular materials, isolates, or substances.DNA, Complementary: 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.DNA: 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).Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.Melanophores: 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.RNA, Ribosomal, 5S: 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.Transcription Factor TFIIIA: 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.Body Patterning: 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.Nervous System: 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)Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Morphogenesis: 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.Nucleoplasmins: 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.RNA: 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)Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Kinetics: The rate dynamics in chemical or physical systems.Animals, Genetically Modified: ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.RNA, Ribosomal: 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)Biological Transport: 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.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Sequence Alignment: 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.TailNotochord: 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.Membrane Potentials: 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).Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Cell Nucleus: 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: 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.Symporters: 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.Species Specificity: 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.Amphibians: VERTEBRATES belonging to the class amphibia such as frogs, toads, newts and salamanders that live in a semiaquatic environment.Sequence Homology, Nucleic Acid: 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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Electrophysiology: 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.Maturation-Promoting Factor: 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.Poly A: 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.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.Blastomeres: 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.Homeodomain Proteins: 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).Egg Proteins: Proteins which are found in eggs (OVA) from any species.Genes: 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.DNA-Binding Proteins: 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.Plasmids: 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.Fertilization: The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.Nucleic Acid Hybridization: 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)Gastrulation: 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.Embryonic Development: Morphological and physiological development of EMBRYOS.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Vitelline Membrane: The plasma membrane of the egg.Blotting, Northern: 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.Signal Transduction: 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.Gene Library: 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.T-Box Domain Proteins: 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.Mutation: 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.Gene Expression Regulation: 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.Anura: 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.Nuclear Proteins: 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.DNA Primers: 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.Neural Crest: 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.Meiosis: 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.Oligonucleotides, Antisense: Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize.Recombinant Fusion Proteins: 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.Ion Channel Gating: 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 Morphogenetic Proteins: 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.Thyroid Hormones: Natural hormones secreted by the THYROID GLAND, such as THYROXINE, and their synthetic analogs.Microscopy, Electron: 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.Endoderm: The inner of the three germ layers of an embryo.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Cell-Free System: 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)Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Mitosis: 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.Albinism: 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.Reverse Transcriptase Polymerase Chain Reaction: 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.Protein Binding: 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.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Bufonidae: The family of true toads belonging to the order Anura. The genera include Bufo, Ansonia, Nectophrynoides, and Atelopus.Models, Biological: 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.Membrane Proteins: 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.Calcium: 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.DNA Restriction Enzymes: 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.RNA, Small Nuclear: 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: 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.Molecular Weight: The sum of the weight of all the atoms in a molecule.Laryngeal Muscles: 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).Chromatin: 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.Tissue Distribution: 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.Proto-Oncogene Proteins c-mos: 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.Matrix Metalloproteinase 11: 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.Eye: 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.Blastocyst: 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.Neural Plate: 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.Fetal Proteins: Proteins that are preferentially expressed or upregulated during FETAL DEVELOPMENT.Muscles: Contractile tissue that produces movement in animals.Sodium Channels: 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, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.DNA Replication: The process by which a DNA molecule is duplicated.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Organ Specificity: Characteristic restricted to a particular organ of the body, such as a cell type, metabolic response or expression of a particular protein or antigen.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Ribonucleoproteins: Complexes of RNA-binding proteins with ribonucleic acids (RNA).Promoter Regions, Genetic: 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.Somites: 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).DNA, Recombinant: 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.Conserved Sequence: 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: 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.Potassium Channels: 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.Regeneration: 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)

  • The genome of the African clawed frog Xenopus laevis (top) is roughly double that of the related western clawed frog X. tropicalis (bottom). (eurekalert.org)
  • In the Oct. 20 issue of the journal Nature, an international research consortium led by scientists from the University of California, Berkeley, and the University of Tokyo reports a striking pattern of genome duplication in the African clawed frog Xenopus laevis. (eurekalert.org)
  • Confirming a longstanding hypothesis, the analysis shows that the long and short sub-genomes of X. laevis were originally derived from two conventional frog species. (eurekalert.org)
  • The African clawed frog Xenopus laevis , native to southern Africa, has established numerous invasive populations on multiple continents making it a pertinent model organism to study environmental niche dynamics. (zfmk.de)
  • Traditionally, we have used cell-free extracts prepared from eggs of the frog Xenopus laevis which can recapitulate cell cycle events and apoptotic processes in vitro. (duke.edu)
  • 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. (unlv.edu)
  • A proteomics analysis was performed on developing Xenopus laevis tadpoles exposed from 2 to 5 days postfertilization to either 0.1 or 1 ppm Aroclor 1254, a PCB mixture. (mcponline.org)
  • The Eomesodermin homolog (Xenopus laevis) protein is a reported synonym for the human gene EOMES, encoding eomesodermin. (biocompare.com)
  • cDNA/RNA hybridization experiments of polysomal and nuclear poly(A)-rich RNA from early tadpole stages of Xenopus laevis revealed that part of the nuclear poly(A)-rich RNA sequences are not present within the polysomal polyadenylated RNA. (mysciencework.com)
  • We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. (elsevier.com)
  • In addition, unlike normal mammalian tissues, which lack α6p, the major form of the α6 integrin present in adult Xenopus is α6p. (elsevier.com)
  • Scientists soon realized that Xenopus was also a valuable and versatile laboratory model for basic biology, enabling studies that shed light on both fundamental mechanisms of vertebrate embryonic development and mechanisms underlying human diseases. (eurekalert.org)
  • CIL:26268, Xenopus laevis laevis, oocyte. (cellimagelibrary.org)
  • We have described previously the sudden O -GlcNAcylation increase occurring during the Xenopus laevis oocyte G 2 /M transition, and we have demonstrated that the inhibition of O -GlcNAc-transferase (OGT) blocked this process, showing that the O -GlcNAcylation dynamism interferes with the cell cycle progression. (mcponline.org)
  • Because of a low expression of O -GlcNAcylation in Xenopus oocyte, classical enrichment of O -GlcNAc-bearing proteins using O -GlcNAc-directed antibodies or wheat germ agglutinin lectin affinity were hard to apply, albeit these techniques allowed the identification of actin and erk2. (mcponline.org)
  • Bound proteins were analyzed by nano-LC-nano-ESI-MS/MS allowing for the identification of an average of 20 X. laevis oocyte O -GlcNAcylated proteins. (mcponline.org)
  • Xenopus laevis oocyte has been widely used as a model for studying the regulation of the cell cycle. (mcponline.org)
  • Distribution of Nup37 and Bub1 on chromosomes assembled in vitro using Xenopus oocyte extracts and treated with (lower panels) or without (lower panels) nocodazole. (ucsd.edu)
  • Here, we describe the expression of MscS-green fluorescent protein (GFP) in Xenopus and use single-channel patch-clamp electrophysiology to show that the mechanosensitive behavior of untagged MscS in oocyte membranes is comparable to that of MscS in E. coli membranes and in reconstituted liposomes. (rupress.org)
  • We conclude that the X. laevis oocyte heterologous expression system is a valid and effective means of studying BCRP function and substrate specificity. (aspetjournals.org)
  • A cloned Xenopus laevis H4 histone gene has been expressed in the X.laevis oocyte nucleus. (epfl.ch)
  • 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. (nih.gov)
  • Even though Xenopus larvae can survive without air for many days, aerial respiration is necessary for other functions: tolerance of hypoxia, normal feeding, locomotion and buoyancy regulation. (biologists.org)
  • Anti-Eomesodermin homolog (Xenopus laevis) antibodies can be readily obtained from commercial sources. (biocompare.com)
  • The Eomesodermin homolog (Xenopus laevis) protein is a reported synonym for the human gene EOMES, encoding eomesodermin. (biocompare.com)
  • Your search returned 26 eomesodermin homolog (Xenopus laevis) Antibodies across 4 suppliers. (biocompare.com)
  • it was subsequently re-isolated in the search for mitotic targets of RanGTP as the homolog of X. laevis TPX2 (Gruss et al. (atlasgeneticsoncology.org)
  • Structural work has confirmed the association of the corresponding residues 284-287 in the Xenopus homolog protein to the "minor" NLS-binding site of importin alpha and has shown a second region (residues 327-330 of Xenopus TPX2) contacting the "major" NLS-binding site (Giesecke and Stewart, 2010). (atlasgeneticsoncology.org)
  • These data indicate that the Xvent-2 protein functioning in Xenopus embryos is regulated not only at the transcription, but at translation and posttranslation as well. (scirp.org)
  • 1. Oestrogen treatment has previously been shown to induce the formation of large amounts of a serum protein, vitellogenin (xenoprotein), in Xenopus laevis . (portlandpress.com)
  • Expression and localization of the Xenopus laevis small heat shock protein, HSPB6 (HSP20), in A6 kidney epithelial cells. (sigmaaldrich.com)
  • X. laevis HSPB6 cDNA encodes a 168 aa protein that contains an α-crystallin domain, a polar C-terminal extension and some possible phosphorylation sites. (sigmaaldrich.com)
  • The Xenopus hsp110 cDNA encodes an 854 amino acid protein, which shares 74% identity with mice and humans. (uwaterloo.ca)
  • In addition they express genes such as matrix gla protein (mgp), alkaline phosphatase, type II collagen, and retinoic acid receptors, representing a valuable tool to analyze expression and regulation of Xenopus cartilage-associated genes. (ualg.pt)
  • Here, we used quantitative methods to assay Drosophila melanogaster and Xenopus laevis models with tissue-specific individual and pairwise knockdown of 14 homologs of genes within the 3q29 region. (gene-tools.com)
  • Interestingly, NCBP2 homologs in Drosophila (Cbp20) and X. laevis (ncbp2) enhanced the phenotypes of homologs of the other 3q29 genes, leading to significant increases in apoptosis that disrupted cellular organization and brain morphology. (gene-tools.com)
  • The African clawed frog ( Xenopus laevis ) is a water-dependent species occurring in a very wide range of habitats, including heavily modified anthropogenic habitats. (cabi.org)
  • Much interest in vertebrate embryology is now focused on early pattern formation in the frog, Xenopus laevis. (nih.gov)
  • The genome of the African clawed frog Xenopus laevis (top) is roughly double that of the related western clawed frog X. tropicalis (bottom). (eurekalert.org)
  • In the Oct. 20 issue of the journal Nature, an international research consortium led by scientists from the University of California, Berkeley, and the University of Tokyo reports a striking pattern of genome duplication in the African clawed frog Xenopus laevis. (eurekalert.org)
  • A T-cell growth factor (TCGF) is produced by antigen- or mitogen-stimulated T lymphocytes from the South African clawed frog Xenopus laevis . (hindawi.com)
  • The Color Atlas of 'Xenopus laevis' Histology provides the first central source on the microscopic anatomy of cells, tissues, and major organs of the adult South African clawed frog, Xenopus laevis . (indigo.ca)
  • Scanning electron micrograph (SEM) Tadpole of the African clawed frog (Xenopus laevis). (sciencephoto.com)
  • The African clawed frog Xenopus laevis , native to southern Africa, has established numerous invasive populations on multiple continents making it a pertinent model organism to study environmental niche dynamics. (zfmk.de)
  • The African clawed frog ( Xenopus laevis ) is a common model organism for developmental and genetic research, but few studies have investigated its welfare needs and current husbandry guidelines aren't supported by quantitative evidence. (nc3rs.org.uk)
  • Age structure and growth of invasive populations of the frog Xenopus laevis in Portugal: a skeletochronological approach 2. (rcaap.pt)
  • These areas overlap with populations of the African Clawed Frog (Xenopus laevis) that has a wide distribution in southern Africa and is found in most water-bodies including those where atrazine residues are detected. (usgs.gov)
  • Confirming a longstanding hypothesis, the analysis shows that the long and short sub-genomes of X. laevis were originally derived from two conventional frog species. (eurekalert.org)
  • Two species of Xenopus are regularly used by biologists, Xenopus laevis and Xenopus tropicalis. (xenbase.org)
  • Very few species of frog can be induced to produce eggs in such a controlled manner, and this is another reason why Xenopus is so popular with developmental and cell biologists. (xenbase.org)
  • Comparing the two species, X.tropicalis has a much shorter life cycle than does X. laevis , growing to adult in 4 months compared with 12 months, making it a faster system to study. (xenbase.org)
  • The visual environment is particularly important for species such as X. laevis , because they are adapted to live in murky waters and use cryptic camouflage as a fundamental defence mechanism, where their mottled green and brown skin provides disguise from predators. (nc3rs.org.uk)
  • The recent development of transgenic Xenopus technology offers the promise that this animal model will be utilized more than ever before. (indigo.ca)
  • To determine whether this pathway occurs in vivo , we developed a transgenic Xenopus laevis model of RP based on the class I rhodopsin mutation Q344Ter (Q350Ter in X. laevis ). (jneurosci.org)
  • To determine whether this mechanism functions in vivo , we generated transgenic Xenopus laevis expressing a representative class I rhodopsin mutation, Q350Ter (analogous to Q344Ter in human rhodopsin), in which the C-terminal five amino acids were truncated. (jneurosci.org)
  • Transgenic Xenopus laevis models were designed to probe the roles of transducin/rhodopsin interactions and lipid modifications in transducin targeting and membrane mobility in rod photoreceptors. (arvojournals.org)
  • Transgenic X. laevis have been produced that express EGFP-fused human rod transducin- subunit (G t1 ) or mutant G t1 subunits which are predicted to be S-palmitoylated (G2A/A3C), N-acylated and S-palmitoylated (A3C), or uncoupled from light-activated rhodopsin (uncG t1 ). (arvojournals.org)
  • This study presents, for the first time, a characterization of HSP110 in Xenopus laevis, adding to the growing knowledge of HSPs in this important model organism. (uwaterloo.ca)
  • Development and characterization of Xl1, a Xenopus laevis chondrocyte-like cell culture. (ualg.pt)
  • We describe the development and characterization of a new cell line, designated Xl1, derived from vertebra and long bones of Xenopus laevis. (ualg.pt)
  • Wade, P. A., Jones, P. L., Vermaak, D., and Wolffe, A. P. (1998) A multiple subunit Mi-2 histone deacetylase from Xenopus laevis cofractionates with an associated Snf2 superfamily ATPase. (springer.com)
  • We first demonstrate that Xenopus laevis Rpd3 (a histone deacetylase) and Sin3 (a corepressor associated to Rpd3) are expressed in premetamorphic and metamorphic tadpole tissues, suggesting their involvement in these postembryonic processes. (spandidos-publications.com)
  • The purpose of this book is to provide the active researcher with a central source of high quality light microscopic color images of the tissues of X. laevis , to aid in the identification of the cells and tissues of interest. (indigo.ca)
  • In this study, the embryotoxicity of ZnONPs (1-100 mg/L) specifically synthesized for industrial purposes with different sizes, shapes (round, rod) and surface coatings (PEG, PVP) was tested using the frog embryo teratogenesis assay- Xenopus (FETAX) to identify potential target tissues and the most sensitive developmental stages. (mdpi.com)
  • W. Kedzierski, W.N. Moghrabi, A.C. Allen, M.M. Jablonski-Stiemke, S. Azarian, D. Bok, and G.H. Travis, 1996, Three homologs of rdsJ.peripherin in Xenopus laevis photoreceptors that exhibit covalent and non-covalent interactions. (springer.com)
  • To investigate the role of rds/J.peripherin in photoreceptor outer segment membrane assembly, we have transfected embryonic Xenopus laevis retinas with phosphorothioated antisense or sense RNA complementary to specific regions of the three Xenopus rds/peripherin homologs. (springer.com)
  • Abstract: There are two populations of Xenopus laevis in Portugal, living in two streams, Laje and Barcarena, located in Oeiras, Portugal. (rcaap.pt)
  • X. laevis embryos were obtained, cytoplasmic extracts prepared, and centrifugation in CsCl or sucrose density gradients were performed as described previously . (scirp.org)
  • The Xenopus laevis egg contains an asymmetric distribution of ribonucleic acids (RNAs), which are parceled out to different cells during cleavage. (els.net)
  • Sequences used in the design of the array were selected from the X. laevis UniGene build 69 (July 2006) and GenBank™ mRNAs (through September 12, 2006). (thermofisher.com)
  • There were no significant relationships between exposure to atrazine and any of the parameters investigated in populations of X. laevis. (usgs.gov)
  • However, we report here that lithium, when applied after specification of the body plan, can respecify the positional system of the Xenopus embryo such that dorsal, axial structures develop from cells that otherwise contribute to ventral structures. (nih.gov)
  • In Xenopus , RNAs localised in the egg initiate formation of both the germ layers and the dorsal axial structures. (els.net)
  • In conclusion, ZnONPs differing in shape and surface coating displayed similar toxicity in X. laevis embryos and shared the same target organ. (mdpi.com)