DNA analogs containing neutral amide backbone linkages composed of aminoethyl glycine units instead of the usual phosphodiester linkage of deoxyribose groups. Peptide nucleic acids have high biological stability and higher affinity for complementary DNA or RNA sequences than analogous DNA oligomers.
Nucleic acid which complements a specific mRNA or DNA molecule, or fragment thereof; used for hybridization studies in order to identify microorganisms and for genetic studies.
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
Nucleic acids which hybridize to complementary sequences in other target nucleic acids causing the function of the latter to be affected.
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 spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.
A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.
Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Occurs in seeds of Brassica and Crucifera species. Thiouracil has been used as antithyroid, coronary vasodilator, and in congestive heart failure although its use has been largely supplanted by other drugs. It is known to cause blood dyscrasias and suspected of terato- and carcinogenesis.
Disruption of the secondary structure of nucleic acids by heat, extreme pH or chemical treatment. Double strand DNA is "melted" by dissociation of the non-covalent hydrogen bonds and hydrophobic interactions. Denatured DNA appears to be a single-stranded flexible structure. The effects of denaturation on RNA are similar though less pronounced and largely reversible.
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 highly fluorescent anti-infective dye used clinically as a topical antiseptic and experimentally as a mutagen, due to its interaction with DNA. It is also used as an intracellular pH indicator.
Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)
An element of the rare earth family of metals. It has the atomic symbol Ce, atomic number 58, and atomic weight 140.12. Cerium is a malleable metal used in industrial applications.
High molecular weight polymers containing a mixture of purine and pyrimidine nucleotides chained together by ribose or deoxyribose linkages.
Peptides that have the ability to enter cells by crossing the plasma membrane directly, or through uptake by the endocytotic pathway.
A group of atoms or molecules attached to other molecules or cellular structures and used in studying the properties of these molecules and structures. Radioactive DNA or RNA sequences are used in MOLECULAR GENETICS to detect the presence of a complementary sequence by NUCLEIC ACID HYBRIDIZATION.
A technique which uses synthetic oligonucleotides to direct the cell's inherent DNA repair system to correct a mutation at a specific site in an episome or chromosome.
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.
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)
DNA that is complementary to the sense strand. (The sense strand has the same sequence as the mRNA transcript. The antisense strand is the template for mRNA synthesis.) Synthetic antisense DNAs are used to hybridize to complementary sequences in target RNAs or DNAs to effect the functioning of specific genes for investigative or therapeutic purposes.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
A group of deoxyribonucleotides (up to 12) in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.
Infection involving the tissues or organs in the PELVIS.
Synthetic or natural oligonucleotides used in hybridization studies in order to identify and study specific nucleic acid fragments, e.g., DNA segments near or within a specific gene locus or gene. The probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the probe include the radioisotope labels 32P and 125I and the chemical label biotin.
The use of devices which use detector molecules to detect, investigate, or analyze other molecules, macromolecules, molecular aggregates, or organisms.
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)
Double-stranded nucleic acid molecules (DNA-DNA or DNA-RNA) which contain regions of nucleotide mismatches (non-complementary). In vivo, these heteroduplexes can result from mutation or genetic recombination; in vitro, they are formed by nucleic acid hybridization. Electron microscopic analysis of the resulting heteroduplexes facilitates the mapping of regions of base sequence homology of nucleic acids.
A collection of cloned peptides, or chemically synthesized peptides, frequently consisting of all possible combinations of amino acids making up an n-amino acid peptide.
Pairing of purine and pyrimidine bases by HYDROGEN BONDING in double-stranded DNA or RNA.
Fungal infections caused by TRICHOSPORON that may become systemic especially in an IMMUNOCOMPROMISED HOST. Clinical manifestations range from superficial cutaneous infections to systemic lesions in multiple organs.
The body fluid that circulates in the vascular system (BLOOD VESSELS). Whole blood includes PLASMA and BLOOD CELLS.
Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.

Versatile derivatisation of solid support media for covalent bonding on DNA-microchips. (1/509)

A chemistry was developed that permits on DNA-arrays both the covalent immobilisation of pre-fabricated nucleic acids-such as oligonucleotides, PCR-products or peptide nucleic acid oligomers-and the in situ synthesis of such compounds on either glass or polypropylene surfaces. Bonding was found to be stable even after some 30 cycles of stripping. Due to a dendrimeric structure of the linker molecule, the loading can be modified in a controlled manner and increased beyond the capacity of glass without negative effects on hybridisation efficiency. Also, the chemistry warrants the modulation of other surface properties such as charge or hydrophobicity. Preferentially, attachment of nucleic acids takes place only via the terminal amino-group of amino-modified oligonucleotides or the terminal hydroxyl-group of unmodified molecules so that the entire molecule is accessible to probe hybridisation. This derivatisation represents a support chemistry versatile enough to serve nearly all current forms of DNA-arrays or microchips.  (+info)

Peptide nucleic acids targeted to the neurotensin receptor and administered i.p. cross the blood-brain barrier and specifically reduce gene expression. (2/509)

Intraperitoneal injection of an unmodified antisense peptide nucleic acid (PNA) complementary to mRNA of the rat neurotensin (NT) receptor (NTR1) was demonstrated by a gel shift assay to be present in brain, thus indicating that the PNA had in fact crossed the blood-brain barrier. An i.p. injection of this antisense PNA specifically inhibited the hypothermic and antinociceptive activities of NT microinjected into brain. These results were associated with a reduction in binding sites for NT both in brain and the small intestine. Additionally, the sense-NTR1 PNA, targeted to DNA, microinjected directly into the brain specifically reduced mRNA levels by 50% and caused a loss of response to NT. To demonstrate the specificity of changes in behavioral, binding, and mRNA studies, animals treated with NTR1 PNA were tested for behavioral responses to morphine and their mu receptor levels were determined. Both were found to be unaffected in these NTR1 PNA-treated animals. The effects of both the antisense and sense PNAs were completely reversible. This work provides evidence that any antisense strategy targeted to brain proteins can work through i. p. delivery by crossing the normal blood-brain barrier. Equally important was that an antigene strategy, the sense PNA, was shown in vivo to be a potentially effective therapeutic treatment.  (+info)

Modified peptide nucleic acids are internalized in mouse macrophages RAW 264.7 and inhibit inducible nitric oxide synthase. (3/509)

Overexpression of inducible nitric oxide synthase causes the production of high levels of nitric oxide, which, under pathological conditions, leads to immunosuppression and tissue damage. The results recently obtained using peptide nucleic acids, rather than traditional oligonucleotides as antigen and antisense molecules, prompted us to test their efficacy in the regulation of nitric oxide production, thereby overcoming the obstacle of cellular internalization. The cellular permeability of four inducible nitric oxide synthase antisense peptide nucleic acids of different lengths was evaluated. These peptide nucleic acids were covalently linked to a hydrophobic peptide moiety to increase internalization and to a tyrosine to allow selective 125I radiolabelling. Internalization experiments showed a 3-25-fold increase in the membrane permeability of the modified peptide nucleic acids with respect to controls. Inducible nitric oxide synthase inhibition experiments on intact stimulated macrophages RAW 264.7 after passive permeation of the two antisense peptide nucleic acids 3 and 4 demonstrated a significant decrease (43-44%) in protein enzymatic activity with respect to the controls. These data offer a basis for developing a good alternative to conventional drugs directed against inducible nitric oxide synthase overexpression.  (+info)

Peptide nucleic acid (PNA) binding-mediated induction of human gamma-globin gene expression. (4/509)

Peptide nucleic acids (PNAs) can bind to homopurine/homopyrimidine sequences of double-stranded DNA targets in a sequence-specific manner and form [PNA]2/DNA triplexes with single-stranded DNA D-loop structures at the PNA binding sites. These D-loop structures have been found to have a capacity to initiate transcription in vitro. If this strategy can be used to induce transcription of endogenous genes, it may provide a novel approach for gene therapy of many human diseases. Human [beta] globin disorders such as sickle cell anemia and beta-thalassemia are very common genetic diseases that are caused by mutations in the beta-globin gene. When gamma-globin genes are highly expressed in sickle cell patients, the presence of high levels of fetal hemoglobin (HbF, alpha2gamma2) can compensate for the defective beta-globin gene product and such patients have much improved symptoms or are free of disease. However, the gamma-globin genes are developmentally regulated and normally expressed at very low levels (>1%) in adult blood cells. We have investigated the possibility of inducing gamma-globin gene expression with PNAs. Using PNAs designed to bind to the 5' flanking region of the gamma-globin gene, induction of expression of a reporter gene construct was demonstrated both in vitro and in vivo. More importantly, PNA-mediated induction of endogenous gamma-globin gene expression was also demonstrated in K562 human erythroleukemia cells. This result suggests that induction of gamma-globin gene expression with PNAs might provide a new approach for the treatment of sickle cell disease. PNA-induced gene expression strategy also may have implications in gene therapy of other diseases such as genetic diseases, cancer and infectious diseases.  (+info)

Cellular delivery of peptide nucleic acids and inhibition of human telomerase. (5/509)

BACKGROUND: Human telomerase has an essential RNA component and is an ideal target for developing rules correlating oligonucleotide chemistry with disruption of biological function. Similarly, peptide nucleic acids (PNAs), DNA analogs that bind complementary sequences with high affinity, are outstanding candidates for inducing phenotypic changes through hybridization. RESULTS: We identify PNAs directed to nontemplate regions of the telomerase RNA that can overcome RNA secondary structure and inhibit telomerase by intercepting the RNA component prior to holoenzyme assembly. Relative potencies of inhibition delineate putative structural domains. We describe a novel protocol for introducing PNAs into eukaryotic cells and report efficient inhibition of cellular telomerase by PNAs. CONCLUSIONS: PNAs directed to nontemplate regions are a new class of telomerase inhibitor and may contribute to the development of novel antiproliferative agents. The dependence of inhibition by nontemplate-directed PNAs on target sequence suggests that PNAs have great potential for mapping nucleic acid structure and predictably regulating biological processes. Our simple method for introducing PNAs into cells will not only be useful for probing the complex biology surrounding telomere length maintenance but can be broadly applied for controlling gene expression and functional genomics.  (+info)

Helical periodicity of (PNA)2.(DNA) triplexes in strand displacement complexes. (6/509)

To study the helical structure in a P-loop formed by an invasion of oligopyrimidine peptide nucleic acid (PNA) into DNA duplex, bent DNA fragments containing a homopurine.homopyrimidine sequence between two bent DNA loci were prepared. As the spacer DNA length between the two bent loci varied by 1 bp over one helical turn, the electrophoretic mobility, reflecting the overall extent of DNA bending, was modulated sinusoidally in non-denaturing 5% polyacrylamide gel. When the bent DNA fragments differing in the spacer DNA length were preincubated with an oligopyrimidine PNA, the gel mobilities were changed due to a P-loop formation. By analyzing the gel mobility data with variations of the P-loop size, average helical parameters at the P-loop structure were determined. (PNA)2. (DNA) triplex within a P-loop had the helical periodicities of 15. 6(0.2) bp per turn at 20 degrees C and 17.4(0.7) bp per turn at 10 degrees C. In addition, the results indicate that a helical unwinding by 57(7) degrees at 20 degrees C and 37(13) degrees at 10 degrees C is present at the two junctions between a P-loop and its adjacent DNA duplex.  (+info)

Nuclear import of plasmid DNA in digitonin-permeabilized cells requires both cytoplasmic factors and specific DNA sequences. (7/509)

Although much is known about the mechanisms of signal-mediated protein and RNA nuclear import and export, little is understood concerning the nuclear import of plasmid DNA. Plasmids between 4.2 and 14.4 kilobases were specifically labeled using a fluorescein-conjugated peptide nucleic acid clamp. The resulting substrates were capable of gene expression and nuclear localization in microinjected cells in the absence of cell division. To elucidate the requirements for plasmid nuclear import, a digitonin-permeabilized cell system was adapted to follow the nuclear localization of plasmids. Nuclear import of labeled plasmid was time- and energy-dependent, was inhibited by the lectin wheat germ agglutinin, and showed an absolute requirement for cytoplasmic extract. Addition of nuclear extract alone did not support plasmid nuclear import but in combination with cytoplasm stimulated plasmid nuclear localization. Whereas addition of purified importin alpha, importin beta, and RAN was sufficient to support protein nuclear import, plasmid nuclear import also required the addition of nuclear extract. Finally, nuclear import of plasmid DNA was sequence-specific, requiring a region of the SV40 early promoter and enhancer. Taken together, these results confirm and extend our findings in microinjected cells and support a protein-mediated mechanism for plasmid nuclear import.  (+info)

Fluorescence In situ hybridization assay using peptide nucleic acid probes for differentiation between tuberculous and nontuberculous mycobacterium species in smears of mycobacterium cultures. (8/509)

TB PNA FISH is a new fluorescence in situ hybridization (FISH) method using peptide nucleic acid (PNA) probes for differentiation between species of the Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) in acid-fast bacillus-positive (AFB+) cultures is described. The test is based on fluorescein-labelled PNA probes that target the rRNA of MTC or NTM species applied to smears of AFB+ cultures for microscopic examination. Parallel testing with the two probes serves as an internal control for each sample such that a valid test result is based on one positive and one negative reaction. TB PNA FISH was evaluated with 30 AFB+ cultures from Denmark and 42 AFB+ cultures from Thailand. The MTC-specific PNA probe showed diagnostic sensitivities of 84 and 97%, respectively, and a diagnostic specificity of 100% in both studies, whereas the NTM-specific PNA probe showed diagnostic sensitivities of 91 and 64%, respectively, and a diagnostic specificity of 100% in both studies. The low sensitivity of the NTM-specific PNA probe in the Thai study was due to a relatively high prevalence of Mycobacterium fortuitum, which is not identified by the probe. In total, 63 (87%) of the cultures were correctly identified as MTC (n = 46) or NTM (n = 17), whereas the remaining 9 were negative with both probes and thus the results were inconclusive. None of the samples were incorrectly identified as MTC or NTM; thus, the predictive value of a valid test result obtained with TB PNA FISH was 100%.  (+info)

Peptide Nucleic Acids (PNAs) are synthetic, artificially produced molecules that have a structure similar to both peptides (short chains of amino acids) and nucleic acids (DNA and RNA). They consist of repeating units called "monomers" made up of a pseudopeptide backbone with nucleobases attached. The backbone is composed of N-(2-aminoethyl)glycine units, which replace the sugar-phosphate backbone found in natural nucleic acids.

PNAs are known for their high binding affinity and sequence-specific recognition of DNA and RNA molecules. They can form stable complexes with complementary DNA or RNA strands through Watson-Crick base pairing, even under conditions where normal nucleic acid hybridization is poor. This property makes them valuable tools in molecular biology for various applications such as:

1. Gene regulation and silencing
2. Antisense and antigen technologies
3. Diagnostics and biosensors
4. Study of protein-DNA interactions
5. DNA repair and mutation analysis

However, it is important to note that Peptide Nucleic Acids are not naturally occurring molecules; they are entirely synthetic and must be produced in a laboratory setting.

Nucleic acid probes are specialized single-stranded DNA or RNA molecules that are used in molecular biology to identify and detect specific nucleic acid sequences, such as genes or fragments of DNA or RNA. These probes are typically labeled with a marker, such as a radioactive isotope or a fluorescent dye, which allows them to be detected and visualized.

Nucleic acid probes work by binding or "hybridizing" to their complementary target sequence through base-pairing interactions between the nucleotides that make up the probe and the target. This specificity of hybridization allows for the detection and identification of specific sequences within a complex mixture of nucleic acids, such as those found in a sample of DNA or RNA from a biological specimen.

Nucleic acid probes are used in a variety of applications, including gene expression analysis, genetic mapping, diagnosis of genetic disorders, and detection of pathogens, among others. They are an essential tool in modern molecular biology research and have contributed significantly to our understanding of genetics and disease.

Peptides are short chains of amino acid residues linked by covalent bonds, known as peptide bonds. They are formed when two or more amino acids are joined together through a condensation reaction, which results in the elimination of a water molecule and the formation of an amide bond between the carboxyl group of one amino acid and the amino group of another.

Peptides can vary in length from two to about fifty amino acids, and they are often classified based on their size. For example, dipeptides contain two amino acids, tripeptides contain three, and so on. Oligopeptides typically contain up to ten amino acids, while polypeptides can contain dozens or even hundreds of amino acids.

Peptides play many important roles in the body, including serving as hormones, neurotransmitters, enzymes, and antibiotics. They are also used in medical research and therapeutic applications, such as drug delivery and tissue engineering.

Deoxyribonucleic acid (DNA) is the genetic material present in the cells of organisms where it is responsible for the storage and transmission of hereditary information. DNA is a long molecule that consists of two strands coiled together to form a double helix. Each strand is made up of a series of four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - that are linked together by phosphate and sugar groups. The sequence of these bases along the length of the molecule encodes genetic information, with A always pairing with T and C always pairing with G. This base-pairing allows for the replication and transcription of DNA, which are essential processes in the functioning and reproduction of all living organisms.

Nucleic acid conformation refers to the three-dimensional structure that nucleic acids (DNA and RNA) adopt as a result of the bonding patterns between the atoms within the molecule. The primary structure of nucleic acids is determined by the sequence of nucleotides, while the conformation is influenced by factors such as the sugar-phosphate backbone, base stacking, and hydrogen bonding.

Two common conformations of DNA are the B-form and the A-form. The B-form is a right-handed helix with a diameter of about 20 Å and a pitch of 34 Å, while the A-form has a smaller diameter (about 18 Å) and a shorter pitch (about 25 Å). RNA typically adopts an A-form conformation.

The conformation of nucleic acids can have significant implications for their function, as it can affect their ability to interact with other molecules such as proteins or drugs. Understanding the conformational properties of nucleic acids is therefore an important area of research in molecular biology and medicine.

In situ hybridization, fluorescence (FISH) is a type of molecular cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes through the use of fluorescent probes. This technique allows for the direct visualization of genetic material at a cellular level, making it possible to identify chromosomal abnormalities such as deletions, duplications, translocations, and other rearrangements.

The process involves denaturing the DNA in the sample to separate the double-stranded molecules into single strands, then adding fluorescently labeled probes that are complementary to the target DNA sequence. The probe hybridizes to the complementary sequence in the sample, and the location of the probe is detected by fluorescence microscopy.

FISH has a wide range of applications in both clinical and research settings, including prenatal diagnosis, cancer diagnosis and monitoring, and the study of gene expression and regulation. It is a powerful tool for identifying genetic abnormalities and understanding their role in human disease.

Antisense oligonucleotides (ASOs) are short synthetic single stranded DNA-like molecules that are designed to complementarily bind to a specific RNA sequence through base-pairing, with the goal of preventing the translation of the target RNA into protein or promoting its degradation.

The antisense oligonucleotides work by hybridizing to the targeted messenger RNA (mRNA) molecule and inducing RNase H-mediated degradation, sterically blocking ribosomal translation, or modulating alternative splicing of the pre-mRNA.

ASOs have shown promise as therapeutic agents for various genetic diseases, viral infections, and cancers by specifically targeting disease-causing genes. However, their clinical application is still facing challenges such as off-target effects, stability, delivery, and potential immunogenicity.

A base sequence in the context of molecular biology refers to the specific order of nucleotides in a DNA or RNA molecule. In DNA, these nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, uracil (U) takes the place of thymine. The base sequence contains genetic information that is transcribed into RNA and ultimately translated into proteins. It is the exact order of these bases that determines the genetic code and thus the function of the DNA or RNA molecule.

Thiouracil is not typically used as a medical treatment in current clinical practice. It is an anti-thyroid medication that was historically used to manage hyperthyroidism, particularly in cases of Graves' disease. However, due to its adverse effect profile and the availability of safer and more effective treatment options, thiouracil has largely been replaced by other medications such as methimazole and propylthiouracil.

Thiouracil works by inhibiting the enzyme thyroperoxidase, which is necessary for the production of thyroid hormones in the body. By blocking this enzyme, thiouracil reduces the amount of thyroid hormones produced and can help to control symptoms of hyperthyroidism such as rapid heart rate, tremors, and weight loss.

While thiouracil is still available for use in some cases, its use is generally reserved for patients who cannot tolerate or have failed other treatments. The medication can cause serious side effects, including liver damage, bone marrow suppression, and allergic reactions, and requires careful monitoring during treatment.

Nucleic acid denaturation is the process of separating the two strands of a double-stranded DNA molecule, or unwinding the helical structure of an RNA molecule, by disrupting the hydrogen bonds that hold the strands together. This process is typically caused by exposure to high temperatures, changes in pH, or the presence of chemicals called denaturants.

Denaturation can also cause changes in the shape and function of nucleic acids. For example, it can disrupt the secondary and tertiary structures of RNA molecules, which can affect their ability to bind to other molecules and carry out their functions within the cell.

In molecular biology, nucleic acid denaturation is often used as a tool for studying the structure and function of nucleic acids. For example, it can be used to separate the two strands of a DNA molecule for sequencing or amplification, or to study the interactions between nucleic acids and other molecules.

It's important to note that denaturation is a reversible process, and under the right conditions, the double-stranded structure of DNA can be restored through a process called renaturation or annealing.

Nucleic acid hybridization is a process in molecular biology where two single-stranded nucleic acids (DNA, RNA) with complementary sequences pair together to form a double-stranded molecule through hydrogen bonding. The strands can be from the same type of nucleic acid or different types (i.e., DNA-RNA or DNA-cDNA). This process is commonly used in various laboratory techniques, such as Southern blotting, Northern blotting, polymerase chain reaction (PCR), and microarray analysis, to detect, isolate, and analyze specific nucleic acid sequences. The hybridization temperature and conditions are critical to ensure the specificity of the interaction between the two strands.

Aminacrine is a type of medication known as an antineoplastic agent or chemotherapeutic drug. It is primarily used in the treatment of certain types of cancer. Aminacrine works by interfering with the DNA replication process within cancer cells, which helps to inhibit the growth and proliferation of these cells.

The chemical name for aminacrine is 9-aminoacridine hydrochloride monohydrate. It has a yellowish crystalline appearance and is typically administered intravenously in a hospital setting. Common side effects of aminacrine include nausea, vomiting, diarrhea, mouth sores, and hair loss. More serious side effects can include heart rhythm abnormalities, seizures, and lung or kidney damage.

It's important to note that the use of aminacrine is typically reserved for cases where other cancer treatments have not been effective, due to its potential for serious side effects. As with all medications, it should be used under the close supervision of a healthcare professional.

Oligonucleotides are short sequences of nucleotides, the building blocks of DNA and RNA. They typically contain fewer than 100 nucleotides, and can be synthesized chemically to have specific sequences. Oligonucleotides are used in a variety of applications in molecular biology, including as probes for detecting specific DNA or RNA sequences, as inhibitors of gene expression, and as components of diagnostic tests and therapies. They can also be used in the study of protein-nucleic acid interactions and in the development of new drugs.

Cerium is a chemical element with the symbol "Ce" and atomic number 58. It belongs to the lanthanide series in the periodic table and is the second element in this series. Cerium is a solid at room temperature, with a silver-white appearance and has a face-centered cubic crystal structure.

In medicine, cerium oxide nanoparticles have been studied for their potential therapeutic applications, particularly in neurodegenerative diseases such as Alzheimer's and Parkinson's disease. These nanoparticles are believed to have antioxidant properties that can help protect neurons from oxidative stress and inflammation. However, more research is needed to fully understand the safety and efficacy of cerium-based therapies in medical treatments.

Nucleic acids are biological macromolecules composed of linear chains of nucleotides. They play crucial roles in the structure and function of cells, serving as the primary information-carrying molecules in all known forms of life. The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is responsible for storing genetic information in a stable form that can be passed down from generation to generation, while RNA plays a key role in translating the genetic code stored in DNA into functional proteins.

Each nucleotide consists of a sugar molecule, a phosphate group, and a nitrogenous base. The sugar in DNA is deoxyribose, while in RNA it is ribose. The nitrogenous bases found in both DNA and RNA include adenine (A), guanine (G), and cytosine (C). Thymine (T) is found in DNA, but uracil (U) takes its place in RNA. These nucleotides are linked together by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of another, forming a long, helical structure with backbones made up of alternating sugar and phosphate groups.

The sequence of these nitrogenous bases along the nucleic acid chain encodes genetic information in the form of codons, which are sets of three consecutive bases that specify particular amino acids or signals for protein synthesis. This information is used to direct the synthesis of proteins through a process called transcription (converting DNA to RNA) and translation (converting RNA to protein).

In summary, nucleic acids are essential biomolecules composed of chains of nucleotides that store, transmit, and express genetic information in cells. They consist of two main types: DNA and RNA, which differ in their sugar type, nitrogenous bases, and functions.

Cell-penetrating peptides (CPPs) are short, typically less than 30 amino acids long, biologically active peptides that have the ability to cross cell membranes and deliver various cargoes into cells. They were first discovered in the early 1990s and since then have gained significant attention due to their potential applications in drug delivery, gene therapy, and diagnostics.

CPPs can be classified into three categories based on their origin: (1) protein-derived CPPs, such as Tat from HIV-1 TAT protein and Penetratin from Drosophila Antennapedia protein; (2) chimeric CPPs, which are created by fusing different parts of various peptides; and (3) synthetic CPPs, which are designed and synthesized de novo.

The mechanism of cell penetration by CPPs is not fully understood but is thought to involve several processes, including endocytosis, direct translocation, and membrane disruption. The ability of CPPs to efficiently deliver various cargoes, such as proteins, nucleic acids, and small molecules, into cells has made them attractive tools for use in biomedical research and therapeutic applications. However, their potential cytotoxicity and lack of specificity remain major challenges that need to be addressed before they can be widely used in clinical settings.

Molecular probes, also known as bioprobes or molecular tracers, are molecules that are used to detect and visualize specific biological targets or processes within cells, tissues, or organisms. These probes can be labeled with a variety of detection methods such as fluorescence, radioactivity, or enzymatic activity. They can bind to specific biomolecules such as DNA, RNA, proteins, or lipids and are used in various fields including molecular biology, cell biology, diagnostic medicine, and medical research.

For example, a fluorescent molecular probe may be designed to bind specifically to a certain protein in a living cell. When the probe binds to its target, it emits a detectable signal that can be observed under a microscope, allowing researchers to track the location and behavior of the protein within the cell.

Molecular probes are valuable tools for understanding biological systems at the molecular level, enabling researchers to study complex processes such as gene expression, signal transduction, and metabolism in real-time. They can also be used in clinical settings for diagnostic purposes, such as detecting specific biomarkers of disease or monitoring the effectiveness of therapies.

Targeted gene repair, also known as genome editing or gene editing, is a medical technique that involves the use of engineered nucleases (enzymes that cut DNA) to introduce precise changes into the DNA of an organism or cell. These engineered nucleases include zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems.

In targeted gene repair, the engineered nuclease is directed to a specific location in the genome, where it creates a double-stranded break in the DNA. This break is then repaired by one of two natural cellular mechanisms: non-homologous end joining (NHEJ) or homology-directed repair (HDR). NHEJ is an error-prone process that can introduce random insertions or deletions (indels) at the site of the break, potentially disrupting gene function. HDR, on the other hand, uses a template to accurately repair the break and introduce specific changes into the genome.

Targeted gene repair has the potential to treat or cure genetic diseases by correcting the underlying genetic defects that cause them. It can also be used to modify the genomes of animals or plants for research or agricultural purposes. However, there are concerns about the potential risks and ethical implications of using this technology in humans, including the possibility of off-target effects and the long-term consequences of genetically modifying human germ cells (sperm or eggs).

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

RNA (Ribonucleic Acid) is a single-stranded, linear polymer of ribonucleotides. It is a nucleic acid present in the cells of all living organisms and some viruses. RNAs play crucial roles in various biological processes such as protein synthesis, gene regulation, and cellular signaling. There are several types of RNA including messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), small nuclear RNA (snRNA), microRNA (miRNA), and long non-coding RNA (lncRNA). These RNAs differ in their structure, function, and location within the cell.

Antisense DNA is a segment of DNA that is complementary to a specific RNA molecule. Unlike the sense strand, which carries the genetic information that gets transcribed into RNA, the antisense strand does not directly code for a protein. Instead, it can bind to the corresponding RNA transcript (known as messenger RNA or mRNA) through base-pairing, forming a double-stranded RNA-DNA hybrid. This interaction can prevent the translation of the mRNA into protein, either by blocking the ribosome from binding and initiating translation or by triggering degradation of the mRNA.

Antisense DNA can be used as a tool in molecular biology to study gene function or as a therapeutic strategy to target specific disease-causing genes. In some cases, antisense oligonucleotides (short synthetic single-stranded DNA molecules) are designed to complement and bind to specific mRNA sequences, leading to their degradation or inhibition of translation. This approach has been explored in the treatment of various genetic diseases, viral infections, and cancers.

It's important to note that antisense RNA also exists, which is transcribed from the DNA strand complementary to the coding (or sense) strand. Antisense RNA plays a role in gene regulation by binding to and inhibiting the translation of specific mRNAs or promoting their degradation.

A peptide fragment is a short chain of amino acids that is derived from a larger peptide or protein through various biological or chemical processes. These fragments can result from the natural breakdown of proteins in the body during regular physiological processes, such as digestion, or they can be produced experimentally in a laboratory setting for research or therapeutic purposes.

Peptide fragments are often used in research to map the structure and function of larger peptides and proteins, as well as to study their interactions with other molecules. In some cases, peptide fragments may also have biological activity of their own and can be developed into drugs or diagnostic tools. For example, certain peptide fragments derived from hormones or neurotransmitters may bind to receptors in the body and mimic or block the effects of the full-length molecule.

Oligodeoxyribonucleotides (ODNs) are relatively short, synthetic single-stranded DNA molecules. They typically contain 15 to 30 nucleotides, but can range from 2 to several hundred nucleotides in length. ODNs are often used as tools in molecular biology research for various applications such as:

1. Nucleic acid detection and quantification (e.g., real-time PCR)
2. Gene regulation (antisense, RNA interference)
3. Gene editing (CRISPR-Cas systems)
4. Vaccine development
5. Diagnostic purposes

Due to their specificity and affinity towards complementary DNA or RNA sequences, ODNs can be designed to target a particular gene or sequence of interest. This makes them valuable tools in understanding gene function, regulation, and interaction with other molecules within the cell.

A pelvic infection, also known as pelvic inflammatory disease (PID), is a medical condition characterized by inflammation of the reproductive organs in females, including the uterus, fallopian tubes, ovaries, and surrounding tissues. It is often caused by an ascending infection from the cervix or vagina, commonly due to sexually transmitted bacteria such as Neisseria gonorrhoeae and Chlamydia trachomatis. However, other organisms can also cause pelvic infections.

Symptoms of pelvic infections may include lower abdominal pain, irregular menstrual bleeding, vaginal discharge with an unpleasant odor, fever, painful intercourse, and difficulty urinating. In some cases, pelvic infections may not cause any noticeable symptoms, making it challenging to diagnose the condition promptly.

If left untreated, pelvic infections can lead to serious complications such as chronic pelvic pain, infertility, ectopic pregnancy, and abscess formation in the reproductive organs. Treatment typically involves antibiotics to eradicate the infection, and in severe cases, hospitalization and surgical intervention may be necessary.

An oligonucleotide probe is a short, single-stranded DNA or RNA molecule that contains a specific sequence of nucleotides designed to hybridize with a complementary sequence in a target nucleic acid (DNA or RNA). These probes are typically 15-50 nucleotides long and are used in various molecular biology techniques, such as polymerase chain reaction (PCR), DNA sequencing, microarray analysis, and blotting methods.

Oligonucleotide probes can be labeled with various reporter molecules, like fluorescent dyes or radioactive isotopes, to enable the detection of hybridized targets. The high specificity of oligonucleotide probes allows for the precise identification and quantification of target nucleic acids in complex biological samples, making them valuable tools in diagnostic, research, and forensic applications.

Molecular probe techniques are analytical methods used in molecular biology and medicine to detect, analyze, and visualize specific biological molecules or cellular structures within cells, tissues, or bodily fluids. These techniques typically involve the use of labeled probes that bind selectively to target molecules, allowing for their detection and quantification.

A molecular probe is a small molecule or biomacromolecule (such as DNA, RNA, peptide, or antibody) that has been tagged with a detectable label, such as a fluorescent dye, radioisotope, enzyme, or magnetic particle. The probe is designed to recognize and bind to a specific target molecule, such as a gene, protein, or metabolite, through complementary base pairing, antigen-antibody interactions, or other forms of molecular recognition.

Molecular probe techniques can be broadly classified into two categories:

1. In situ hybridization (ISH): This technique involves the use of labeled DNA or RNA probes to detect specific nucleic acid sequences within cells or tissues. The probes are designed to complement the target sequence and, upon hybridization, allow for the visualization of the location and quantity of the target molecule using various detection methods, such as fluorescence microscopy, brightfield microscopy, or radioisotopic imaging.
2. Immunohistochemistry (IHC) and immunofluorescence (IF): These techniques utilize antibodies as probes to detect specific proteins within cells or tissues. Primary antibodies are raised against a target protein and, upon binding, can be detected using various methods, such as enzyme-linked secondary antibodies, fluorescent dyes, or gold nanoparticles. IHC is typically used for brightfield microscopy, while IF is used for fluorescence microscopy.

Molecular probe techniques have numerous applications in basic research, diagnostics, and therapeutics, including gene expression analysis, protein localization, disease diagnosis, drug development, and targeted therapy.

Sensitivity and specificity are statistical measures used to describe the performance of a diagnostic test or screening tool in identifying true positive and true negative results.

* Sensitivity refers to the proportion of people who have a particular condition (true positives) who are correctly identified by the test. It is also known as the "true positive rate" or "recall." A highly sensitive test will identify most or all of the people with the condition, but may also produce more false positives.
* Specificity refers to the proportion of people who do not have a particular condition (true negatives) who are correctly identified by the test. It is also known as the "true negative rate." A highly specific test will identify most or all of the people without the condition, but may also produce more false negatives.

In medical testing, both sensitivity and specificity are important considerations when evaluating a diagnostic test. High sensitivity is desirable for screening tests that aim to identify as many cases of a condition as possible, while high specificity is desirable for confirmatory tests that aim to rule out the condition in people who do not have it.

It's worth noting that sensitivity and specificity are often influenced by factors such as the prevalence of the condition in the population being tested, the threshold used to define a positive result, and the reliability and validity of the test itself. Therefore, it's important to consider these factors when interpreting the results of a diagnostic test.

A nucleic acid heteroduplex is a double-stranded structure formed by the pairing of two complementary single strands of nucleic acids (DNA or RNA) that are derived from different sources. The term "hetero" refers to the fact that the two strands are not identical and come from different parents, genes, or organisms.

Heteroduplexes can form spontaneously during processes like genetic recombination, where DNA repair mechanisms may mistakenly pair complementary regions between two different double-stranded DNA molecules. They can also be generated intentionally in laboratory settings for various purposes, such as analyzing the similarity of DNA sequences or detecting mutations.

Heteroduplexes are often used in molecular biology techniques like polymerase chain reaction (PCR) and DNA sequencing, where they can help identify mismatches, insertions, deletions, or other sequence variations between the two parental strands. These variations can provide valuable information about genetic diversity, evolutionary relationships, and disease-causing mutations.

A peptide library is a collection of a large number of peptides, which are short chains of amino acids. Each peptide in the library is typically composed of a defined length and sequence, and may contain a variety of different amino acids. Peptide libraries can be synthesized using automated techniques and are often used in scientific research to identify potential ligands (molecules that bind to specific targets) or to study the interactions between peptides and other molecules.

In a peptide library, each peptide is usually attached to a solid support, such as a resin bead, and the entire library can be created using split-and-pool synthesis techniques. This allows for the rapid and efficient synthesis of a large number of unique peptides, which can then be screened for specific activities or properties.

Peptide libraries are used in various fields such as drug discovery, proteomics, and molecular biology to identify potential therapeutic targets, understand protein-protein interactions, and develop new diagnostic tools.

Base pairing is a specific type of chemical bonding that occurs between complementary base pairs in the nucleic acid molecules DNA and RNA. In DNA, these bases are adenine (A), thymine (T), guanine (G), and cytosine (C). Adenine always pairs with thymine via two hydrogen bonds, while guanine always pairs with cytosine via three hydrogen bonds. This precise base pairing is crucial for the stability of the double helix structure of DNA and for the accurate replication and transcription of genetic information. In RNA, uracil (U) takes the place of thymine and pairs with adenine.

Trichosporonosis is a fungal infection caused by the organism Trichosporon spp., which are commonly found in the environment, particularly in soil and water. This infection primarily affects the skin and nails but can also cause invasive systemic disease, especially in immunocompromised individuals. The symptoms of trichosporonosis vary depending on the location and severity of the infection. Superficial infections may present as white plaques or pustules on the mucous membranes, while invasive infections can cause fever, chills, and organ dysfunction. Treatment typically involves antifungal medications, with the choice of drug depending on the severity and location of the infection.

Blood is the fluid that circulates in the body of living organisms, carrying oxygen and nutrients to the cells and removing carbon dioxide and other waste products. It is composed of red and white blood cells suspended in a liquid called plasma. The main function of blood is to transport oxygen from the lungs to the body's tissues and carbon dioxide from the tissues to the lungs. It also transports nutrients, hormones, and other substances to the cells and removes waste products from them. Additionally, blood plays a crucial role in the body's immune system by helping to fight infection and disease.

A DNA probe is a single-stranded DNA molecule that contains a specific sequence of nucleotides, and is labeled with a detectable marker such as a radioisotope or a fluorescent dye. It is used in molecular biology to identify and locate a complementary sequence within a sample of DNA. The probe hybridizes (forms a stable double-stranded structure) with its complementary sequence through base pairing, allowing for the detection and analysis of the target DNA. This technique is widely used in various applications such as genetic testing, diagnosis of infectious diseases, and forensic science.

No FAQ available that match "peptide nucleic acids"

No images available that match "peptide nucleic acids"