Peptide Nucleic Acids: 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 Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Nucleic Acid Probes: 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.Nucleic Acid Amplification Techniques: Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template.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)Nucleic Acid Denaturation: 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.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).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)Oligonucleotides: 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)Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Self-Sustained Sequence Replication: An isothermal in-vitro nucleotide amplification process. The process involves the concomitant action of a RNA-DIRECTED DNA POLYMERASE, a ribonuclease (RIBONUCLEASES), and DNA-DIRECTED RNA POLYMERASES to synthesize large quantities of sequence-specific RNA and DNA molecules.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.RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.DNA, Single-Stranded: A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.DNA Probes: 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.Sensitivity and Specificity: 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)Aptamers, Nucleotide: Nucleotide sequences, generated by iterative rounds of SELEX APTAMER TECHNIQUE, that bind to a target molecule specifically and with high affinity.RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Nucleic Acid Heteroduplexes: 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.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Base Pairing: Pairing of purine and pyrimidine bases by HYDROGEN BONDING in double-stranded DNA or RNA.Oligodeoxyribonucleotides: 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.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.Polyribonucleotides: A group of 13 or more ribonucleotides in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.DNA, Catalytic: Molecules of DNA that possess enzymatic activity.Viruses: Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells.G-Quadruplexes: Higher-order DNA and RNA structures formed from guanine-rich sequences. They are formed around a core of at least 2 stacked tetrads of hydrogen-bonded GUANINE bases. They can be formed from one two or four separate strands of DNA (or RNA) and can display a wide variety of topologies, which are a consequence of various combinations of strand direction, length, and sequence. (From Nucleic Acids Res. 2006;34(19):5402-15)Oligonucleotide Probes: 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.PolynucleotidesIntercalating Agents: Agents that are capable of inserting themselves between the successive bases in DNA, thus kinking, uncoiling or otherwise deforming it and therefore preventing its proper functioning. They are used in the study of DNA.Oligonucleotides, Antisense: Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize.Nucleotides: The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)GuanineMolecular Diagnostic Techniques: MOLECULAR BIOLOGY techniques used in the diagnosis of disease.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Nucleosides: Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Immobilized Nucleic Acids: DNA or RNA bound to a substrate thereby having fixed positions.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Kinetics: The rate dynamics in chemical or physical systems.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Nucleic Acid Renaturation: The reformation of all, or part of, the native conformation of a nucleic acid molecule after the molecule has undergone denaturation.Purines: A series of heterocyclic compounds that are variously substituted in nature and are known also as purine bases. They include ADENINE and GUANINE, constituents of nucleic acids, as well as many alkaloids such as CAFFEINE and THEOPHYLLINE. Uric acid is the metabolic end product of purine metabolism.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.DNA, B-Form: The most common form of DNA found in nature. It is a right-handed helix with 10 base pairs per turn, a pitch of 0.338 nm per base pair and a helical diameter of 1.9 nm.Databases, Nucleic Acid: Databases containing information about NUCLEIC ACIDS such as BASE SEQUENCE; SNPS; NUCLEIC ACID CONFORMATION; and other properties. Information about the DNA fragments kept in a GENE LIBRARY or GENOMIC LIBRARY is often maintained in DNA databases.SELEX Aptamer Technique: A method of generating a large library of randomized nucleotides and selecting NUCLEOTIDE APTAMERS by iterative rounds of in vitro selection. A modified procedure substitutes AMINO ACIDS in place of NUCLEOTIDES to make PEPTIDE APTAMERS.Molecular Probe Techniques: The use of devices which use detector molecules to detect, investigate, or analyze other molecules, macromolecules, molecular aggregates, or organisms.UridineTemperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Virology: The study of the structure, growth, function, genetics, and reproduction of viruses, and VIRUS DISEASES.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Ribonucleases: Enzymes that catalyze the hydrolysis of ester bonds within RNA. EC 3.1.-.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.Oligoribonucleotides: A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.UracilRNA Probes: RNA, usually prepared by transcription from cloned DNA, which complements a specific mRNA or DNA and is generally used for studies of virus genes, distribution of specific RNA in tissues and cells, integration of viral DNA into genomes, transcription, etc. Whereas DNA PROBES are preferred for use at a more macroscopic level for detection of the presence of DNA/RNA from specific species or subspecies, RNA probes are preferred for genetic studies. Conventional labels for the RNA probe include radioisotope labels 32P and 125I and the chemical label biotin. RNA probes may be further divided by category into plus-sense RNA probes, minus-sense RNA probes, and antisense RNA probes.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.Proflavine: Topical antiseptic used mainly in wound dressings.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Molecular Probes: 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.Guanosine: A purine nucleoside that has guanine linked by its N9 nitrogen to the C1 carbon of ribose. It is a component of ribonucleic acid and its nucleotides play important roles in metabolism. (From Dorland, 28th ed)Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Viral Proteins: Proteins found in any species of virus.Spectrophotometry, Ultraviolet: Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Adenine: A purine base and a fundamental unit of ADENINE NUCLEOTIDES.RNA-Binding Proteins: Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.Polydeoxyribonucleotides: A group of 13 or more deoxyribonucleotides in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.Software: Sequential operating programs and data which instruct the functioning of a digital computer.Reverse Transcription: The biosynthesis of DNA carried out on a template of RNA.Reagent Kits, Diagnostic: Commercially prepared reagent sets, with accessory devices, containing all of the major components and literature necessary to perform one or more designated diagnostic tests or procedures. They may be for laboratory or personal use.Specimen Handling: Procedures for collecting, preserving, and transporting of specimens sufficiently stable to provide accurate and precise results suitable for clinical interpretation.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.Cytosine: A pyrimidine base that is a fundamental unit of nucleic acids.Deoxyribonucleases: Enzymes which catalyze the hydrolases of ester bonds within DNA. EC 3.1.-.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.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Ribonuclease H: A ribonuclease that specifically cleaves the RNA moiety of RNA:DNA hybrids. It has been isolated from a wide variety of prokaryotic and eukaryotic organisms as well as RETROVIRUSES.Circular Dichroism: A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)RNA, Double-Stranded: RNA consisting of two strands as opposed to the more prevalent single-stranded RNA. Most of the double-stranded segments are formed from transcription of DNA by intramolecular base-pairing of inverted complementary sequences separated by a single-stranded loop. Some double-stranded segments of RNA are normal in all organisms.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Cell Line: Established cell cultures that have the potential to propagate indefinitely.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)Poly G: A group of guanine ribonucleotides in which the phosphate residues of each guanine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.ComputersTritiumBacteriological Techniques: Techniques used in studying bacteria.Molecular Biology: A discipline concerned with studying biological phenomena in terms of the chemical and physical interactions of molecules.Antisense Elements (Genetics): Nucleic acids which hybridize to complementary sequences in other target nucleic acids causing the function of the latter to be affected.Phosphorothioate Oligonucleotides: Modified oligonucleotides in which one of the oxygens of the phosphate group is replaced with a sulfur atom.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.Hydrogen Bonding: A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.Ribose: A pentose active in biological systems usually in its D-form.Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Biosensing Techniques: Any of a variety of procedures which use biomolecular probes to measure the presence or concentration of biological molecules, biological structures, microorganisms, etc., by translating a biochemical interaction at the probe surface into a quantifiable physical signal.DNA, A-Form: An isoform of DNA that occurs in an environment rich in SODIUM and POTASSIUM ions. It is a right-handed helix with 11 base pairs per turn, a pitch of 0.256 nm per base pair and a helical diameter of 2.3 nm.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.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.Chlamydia trachomatis: Type species of CHLAMYDIA causing a variety of ocular and urogenital diseases.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.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.HIV-1: The type species of LENTIVIRUS and the etiologic agent of AIDS. It is characterized by its cytopathic effect and affinity for the T4-lymphocyte.Staining and Labeling: The marking of biological material with a dye or other reagent for the purpose of identifying and quantitating components of tissues, cells or their extracts.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.Nucleocapsid Proteins: Viral proteins found in either the NUCLEOCAPSID or the viral core (VIRAL CORE PROTEINS).Base Pair Mismatch: The presence of an uncomplimentary base in double-stranded DNA caused by spontaneous deamination of cytosine or adenine, mismatching during homologous recombination, or errors in DNA replication. Multiple, sequential base pair mismatches lead to formation of heteroduplex DNA; (NUCLEIC ACID HETERODUPLEXES).Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Virus Diseases: A general term for diseases produced by viruses.ThymineRNA, Transfer: The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.Poly C: A group of cytosine ribonucleotides in which the phosphate residues of each cytosine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.Poly A-U: A double-stranded polyribonucleotide comprising polyadenylic and polyuridylic acids.RNA, Catalytic: RNA that has catalytic activity. The catalytic RNA sequence folds to form a complex surface that can function as an enzyme in reactions with itself and other molecules. It may function even in the absence of protein. There are numerous examples of RNA species that are acted upon by catalytic RNA, however the scope of this enzyme class is not limited to a particular type of substrate.Chlamydia Infections: Infections with bacteria of the genus CHLAMYDIA.Ethidium: A trypanocidal agent and possible antiviral agent that is widely used in experimental cell biology and biochemistry. Ethidium has several experimentally useful properties including binding to nucleic acids, noncompetitive inhibition of nicotinic acetylcholine receptors, and fluorescence among others. It is most commonly used as the bromide.Inverted Repeat Sequences: Copies of nucleic acid sequence that are arranged in opposing orientation. They may lie adjacent to each other (tandem) or be separated by some sequence that is not part of the repeat (hyphenated). They may be true palindromic repeats, i.e. read the same backwards as forward, or complementary which reads as the base complement in the opposite orientation. Complementary inverted repeats have the potential to form hairpin loop or stem-loop structures which results in cruciform structures (such as CRUCIFORM DNA) when the complementary inverted repeats occur in double stranded regions.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.gag Gene Products, Human Immunodeficiency Virus: Proteins encoded by the GAG GENE of the HUMAN IMMUNODEFICIENCY VIRUS.Nanostructures: Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.Electrophoresis, Agar Gel: Electrophoresis in which agar or agarose gel is used as the diffusion medium.Methods: A series of steps taken in order to conduct research.Streptavidin: A 60-kDa extracellular protein of Streptomyces avidinii with four high-affinity biotin binding sites. Unlike AVIDIN, streptavidin has a near neutral isoelectric point and is free of carbohydrate side chains.Solutions: The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)AcridinesReproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Polyethyleneimine: Strongly cationic polymer that binds to certain proteins; used as a marker in immunology, to precipitate and purify enzymes and lipids. Synonyms: aziridine polymer; Epamine; Epomine; ethylenimine polymer; Montrek; PEI; Polymin(e).Directories as Topic: Lists of persons or organizations, systematically arranged, usually in alphabetic or classed order, giving address, affiliations, etc., for individuals, and giving address, officers, functions, and similar data for organizations. (ALA Glossary of Library and Information Science, 1983)Indicators and Reagents: Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)Computers, Molecular: Computers whose input, output and state transitions are carried out by biochemical interactions and reactions.Tissue Fixation: The technique of using FIXATIVES in the preparation of cytologic, histologic, or pathologic specimens for the purpose of maintaining the existing form and structure of all the constituent elements.Polylysine: A peptide which is a homopolymer of lysine.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Blood: The body fluid that circulates in the vascular system (BLOOD VESSELS). Whole blood includes PLASMA and BLOOD CELLS.Templates, Genetic: Macromolecular molds for the synthesis of complementary macromolecules, as in DNA REPLICATION; GENETIC TRANSCRIPTION of DNA to RNA, and GENETIC TRANSLATION of RNA into POLYPEPTIDES.Repetitive Sequences, Nucleic Acid: Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).DNA Contamination: The presence of DNA from a source foreign to the sample being analysed.Cytidine: A pyrimidine nucleoside that is composed of the base CYTOSINE linked to the five-carbon sugar D-RIBOSE.Nanotechnology: The development and use of techniques to study physical phenomena and construct structures in the nanoscale size range or smaller.ThymidineProtein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Bacterial Proteins: Proteins found in any species of bacterium.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Static Electricity: The accumulation of an electric charge on a objectPoly U: A group of uridine ribonucleotides in which the phosphate residues of each uridine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.Ligase Chain Reaction: A DNA amplification technique based upon the ligation of OLIGONUCLEOTIDE PROBES. The probes are designed to exactly match two adjacent sequences of a specific target DNA. The chain reaction is repeated in three steps in the presence of excess probe: (1) heat denaturation of double-stranded DNA, (2) annealing of probes to target DNA, and (3) joining of the probes by thermostable DNA ligase. After the reaction is repeated for 20-30 cycles the production of ligated probe is measured.Gonorrhea: Acute infectious disease characterized by primary invasion of the urogenital tract. The etiologic agent, NEISSERIA GONORRHOEAE, was isolated by Neisser in 1879.Organic Chemicals: A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form.Transition Temperature: The temperature at which a substance changes from one state or conformation of matter to another.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Nucleic Acids, Nucleotides, and Nucleosides: Complex compounds of high molecular weight occurring in living cells. These are basically of two types, ribonucleic (RNA) and deoxyribonucleic (DNA) acids, both of which consist of nucleotides (nucleoside phosphates linked together by phosphate bridges).Molecular Weight: The sum of the weight of all the atoms in a molecule.Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Centrifugation, Density Gradient: Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)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.Biogenesis: The origin of life. It includes studies of the potential basis for life in organic compounds but excludes studies of the development of altered forms of life through mutation and natural selection, which is BIOLOGICAL EVOLUTION.Phosphorus Isotopes: Stable phosphorus atoms that have the same atomic number as the element phosphorus, but differ in atomic weight. P-31 is a stable phosphorus isotope.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Genetic Techniques: Chromosomal, biochemical, intracellular, and other methods used in the study of genetics.Nanoparticles: Nanometer-sized particles that are nanoscale in three dimensions. They include nanocrystaline materials; NANOCAPSULES; METAL NANOPARTICLES; DENDRIMERS, and QUANTUM DOTS. The uses of nanoparticles include DRUG DELIVERY SYSTEMS and cancer targeting and imaging.Hot Temperature: Presence of warmth or heat or a temperature notably higher than an accustomed norm.RNA Viruses: Viruses whose genetic material is RNA.RNA-Directed DNA Polymerase: An enzyme that synthesizes DNA on an RNA template. It is encoded by the pol gene of retroviruses and by certain retrovirus-like elements. EC 188.8.131.52.Time Factors: Elements of limited time intervals, contributing to particular results or situations.DNA Helicases: Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.Fluorescence Resonance Energy Transfer: A type of FLUORESCENCE SPECTROSCOPY using two FLUORESCENT DYES with overlapping emission and absorption spectra, which is used to indicate proximity of labeled molecules. This technique is useful for studying interactions of molecules and PROTEIN FOLDING.Peptides: 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.Ribostamycin: A broad-spectrum antimicrobial isolated from Streptomyces ribosifidicus.Minicomputers: Small computers that lack the speed, memory capacity, and instructional capability of the full-size computer but usually retain its programmable flexibility. They are larger, faster, and more flexible, powerful, and expensive than microcomputers.HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Neisseria gonorrhoeae: A species of gram-negative, aerobic bacteria primarily found in purulent venereal discharges. It is the causative agent of GONORRHEA.Framycetin: A component of NEOMYCIN that is produced by Streptomyces fradiae. On hydrolysis it yields neamine and neobiosamine B. (From Merck Index, 11th ed)Salts: Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)Enterovirus: A genus of the family PICORNAVIRIDAE whose members preferentially inhabit the intestinal tract of a variety of hosts. The genus contains many species. Newly described members of human enteroviruses are assigned continuous numbers with the species designated "human enterovirus".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.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Cations: Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.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.Cell-Penetrating Peptides: Peptides that have the ability to enter cells by crossing the plasma membrane directly, or through uptake by the endocytotic pathway.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Molecular Chaperones: A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.Chromatography: Techniques used to separate mixtures of substances based on differences in the relative affinities of the substances for mobile and stationary phases. A mobile phase (fluid or gas) passes through a column containing a stationary phase of porous solid or liquid coated on a solid support. Usage is both analytical for small amounts and preparative for bulk amounts.DNA-Directed RNA Polymerases: Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).Toll-Like Receptor 9: A pattern recognition receptor that binds unmethylated CPG CLUSTERS. It mediates cellular responses to bacterial pathogens by distinguishing between self and bacterial DNA.Virus Replication: The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.Pyrimidine Nucleotides: Pyrimidines with a RIBOSE and phosphate attached that can polymerize to form DNA and RNA.Base Composition: The relative amounts of the PURINES and PYRIMIDINES in a nucleic acid.Levivirus: A bacteriophage genus of the family LEVIVIRIDAE, whose viruses contain the short version of the genome and have a separate gene for cell lysis.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.Poly T: A group of thymine nucleotides in which the phosphate residues of each thymine nucleotide act as bridges in forming diester linkages between the deoxyribose moieties.Orotic AcidSugar Alcohols: Polyhydric alcohols having no more than one hydroxy group attached to each carbon atom. They are formed by the reduction of the carbonyl group of a sugar to a hydroxyl group.(From Dorland, 28th ed)Bacteriophages: Viruses whose hosts are bacterial cells.In Situ Hybridization, Fluorescence: 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.Fluorescence: The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.