Complex Mixtures: Mixtures of many components in inexact proportions, usually natural, such as PLANT EXTRACTS; VENOMS; and MANURE. These are distinguished from DRUG COMBINATIONS which have only a few components in definite proportions.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Spectrometry, Mass, Electrospray Ionization: A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.Polycyclic Compounds: Compounds consisting of two or more fused ring structures.Air Pollutants: Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or material. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.HydrocarbonsProteomics: The systematic study of the complete complement of proteins (PROTEOME) of organisms.Fuel Oils: Complex petroleum hydrocarbons consisting mainly of residues from crude oil distillation. These liquid products include heating oils, stove oils, and furnace oils and are burned to generate energy.Smog: A mixture of smoke and fog polluting the atmosphere. (Dorland, 27th ed)Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Chromatography, Liquid: Chromatographic techniques in which the mobile phase is a liquid.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Petroleum: Naturally occurring complex liquid hydrocarbons which, after distillation, yield combustible fuels, petrochemicals, and lubricants.Polycyclic Hydrocarbons, Aromatic: A major group of unsaturated cyclic hydrocarbons containing two or more rings. The vast number of compounds of this important group, derived chiefly from petroleum and coal tar, are rather highly reactive and chemically versatile. The name is due to the strong and not unpleasant odor characteristic of most substances of this nature. (From Hawley's Condensed Chemical Dictionary, 12th ed, p96)Polychlorinated Biphenyls: Industrial products consisting of a mixture of chlorinated biphenyl congeners and isomers. These compounds are highly lipophilic and tend to accumulate in fat stores of animals. Many of these compounds are considered toxic and potential environmental pollutants.Environmental Pollutants: Substances or energies, for example heat or light, which when introduced into the air, water, or land threaten life or health of individuals or ECOSYSTEMS.Water Pollutants, Chemical: Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.Coal Tar: A by-product of the destructive distillation of coal used as a topical antieczematic. It is an antipruritic and keratoplastic agent used also in the treatment of psoriasis and other skin conditions. Occupational exposure to soots, tars, and certain mineral oils is known to be carcinogenic according to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985) (Merck Index, 11th ed).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.Tandem Mass Spectrometry: A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.Odors: The volatile portions of substances perceptible by the sense of smell. (Grant & Hackh's Chemical Dictionary, 5th ed)Benzo(a)pyrene: A potent mutagen and carcinogen. It is a public health concern because of its possible effects on industrial workers, as an environmental pollutant, an as a component of tobacco smoke.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.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.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.United States Environmental Protection Agency: An agency in the Executive Branch of the Federal Government. It was created as an independent regulatory agency responsible for the implementation of federal laws designed to protect the environment. Its mission is to protect human health and the ENVIRONMENT.Proteome: The protein complement of an organism coded for by its genome.Volatilization: A phase transition from liquid state to gas state, which is affected by Raoult's law. It can be accomplished by fractional distillation.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.Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization: A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis.Mutagenicity Tests: Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.Air Pollution, Indoor: The contamination of indoor air.Dioxins: Chlorinated hydrocarbons containing heteroatoms that are present as contaminants of herbicides. Dioxins are carcinogenic, teratogenic, and mutagenic. They have been banned from use by the FDA.Toxicity Tests: An array of tests used to determine the toxicity of a substance to living systems. These include tests on clinical drugs, foods, and environmental pollutants.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.Hazardous Waste: Waste products which threaten life, health, or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.DNA Adducts: The products of chemical reactions that result in the addition of extraneous chemical groups to DNA.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.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.Chemical Fractionation: Separation of a mixture in successive stages, each stage removing from the mixture some proportion of one of the substances, for example by differential solubility in water-solvent mixtures. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Particulate Matter: Particles of any solid substance, generally under 30 microns in size, often noted as PM30. There is special concern with PM1 which can get down to PULMONARY ALVEOLI and induce MACROPHAGE ACTIVATION and PHAGOCYTOSIS leading to FOREIGN BODY REACTION and LUNG DISEASES.Electrophoresis, Microchip: A highly miniaturized version of ELECTROPHORESIS performed in a microfluidic device.Chemistry Techniques, Analytical: Methodologies used for the isolation, identification, detection, and quantitation of chemical substances.Coal: A natural fuel formed by partial decomposition of vegetable matter under certain environmental conditions.Benzene DerivativesCarcinogens: Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.Ions: An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.SmokeBiological Assay: A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.Benzopyrenes: A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it.Xenobiotics: Chemical substances that are foreign to the biological system. They include naturally occurring compounds, drugs, environmental agents, carcinogens, insecticides, etc.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Chromatography, Ion Exchange: Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.Benzofurans: Compounds that contain a BENZENE ring fused to a furan ring.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).Gases: The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)Carbohydrate Sequence: The sequence of carbohydrates within POLYSACCHARIDES; GLYCOPROTEINS; and GLYCOLIPIDS.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Environmental Exposure: The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.Reproducibility 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.Aerosols: Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.Cytochrome P-450 CYP1A1: A liver microsomal cytochrome P-450 monooxygenase capable of biotransforming xenobiotics such as polycyclic hydrocarbons and halogenated aromatic hydrocarbons into carcinogenic or mutagenic compounds. They have been found in mammals and fish. This enzyme, encoded by CYP1A1 gene, can be measured by using ethoxyresorufin as a substrate for the ethoxyresorufin O-deethylase activity.Smell: The ability to detect scents or odors, such as the function of OLFACTORY RECEPTOR NEURONS.Solvents: Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Mutagens: Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.Oligosaccharides: Carbohydrates consisting of between two (DISACCHARIDES) and ten MONOSACCHARIDES connected by either an alpha- or beta-glycosidic link. They are found throughout nature in both the free and bound form.Vehicle Emissions: Gases, fumes, vapors, and odors escaping from the cylinders of a gasoline or diesel internal-combustion engine. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Random House Unabridged Dictionary, 2d ed)Particle Size: Relating to the size of solids.Occupational Exposure: The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.Epidemiological Monitoring: Collection, analysis, and interpretation of data about the frequency, distribution, and consequences of disease or health conditions, for use in the planning, implementing, and evaluating public health programs.Metabolomics: The systematic identification and quantitation of all the metabolic products of a cell, tissue, organ, or organism under varying conditions. The METABOLOME of a cell or organism is a dynamic collection of metabolites which represent its net response to current conditions.Peptide Mapping: Analysis of PEPTIDES that are generated from the digestion or fragmentation of a protein or mixture of PROTEINS, by ELECTROPHORESIS; CHROMATOGRAPHY; or MASS SPECTROMETRY. The resulting peptide fingerprints are analyzed for a variety of purposes including the identification of the proteins in a sample, GENETIC POLYMORPHISMS, patterns of gene expression, and patterns diagnostic for diseases.Glycopeptides: Proteins which contain carbohydrate groups attached covalently to the polypeptide chain. The protein moiety is the predominant group with the carbohydrate making up only a small percentage of the total weight.Cell Extracts: Preparations of cell constituents or subcellular materials, isolates, or substances.Dust: Earth or other matter in fine, dry particles. (Random House Unabridged Dictionary, 2d ed)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)Trypsin: A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 220.127.116.11.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Tobacco Smoke Pollution: Contamination of the air by tobacco smoke.Isotope Labeling: Techniques for labeling a substance with a stable or radioactive isotope. It is not used for articles involving labeled substances unless the methods of labeling are substantively discussed. Tracers that may be labeled include chemical substances, cells, or microorganisms.Tetrachlorodibenzodioxin: A chemical by-product that results from burning or incinerating chlorinated industrial chemicals and other hydrocarbons. This compound is considered an environmental toxin, and may pose reproductive, as well as, other health risks for animals and humans.EstersDrug Interactions: The action of a drug that may affect the activity, metabolism, or toxicity of another drug.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Isomerism: The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Receptors, Aryl Hydrocarbon: Cytoplasmic proteins that bind certain aryl hydrocarbons, translocate to the nucleus, and activate transcription of particular DNA segments. AH receptors are identified by their high-affinity binding to several carcinogenic or teratogenic environmental chemicals including polycyclic aromatic hydrocarbons found in cigarette smoke and smog, heterocyclic amines found in cooked foods, and halogenated hydrocarbons including dioxins and polychlorinated biphenyls. No endogenous ligand has been identified, but an unknown natural messenger with a role in cell differentiation and development is suspected.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Nanotechnology: The development and use of techniques to study physical phenomena and construct structures in the nanoscale size range or smaller.PolysaccharidesMolecular Weight: The sum of the weight of all the atoms in a molecule.Kinetics: The rate dynamics in chemical or physical systems.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).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.Air Pollutants, Occupational: Air pollutants found in the work area. They are usually produced by the specific nature of the occupation.Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.Time Factors: Elements of limited time intervals, contributing to particular results or situations.PhosphopeptidesBlood Proteins: Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Electrophoresis, Gel, Two-Dimensional: Electrophoresis in which a second perpendicular electrophoretic transport is performed on the separate components resulting from the first electrophoresis. This technique is usually performed on polyacrylamide gels.Reference Standards: A basis of value established for the measure of quantity, weight, extent or quality, e.g. weight standards, standard solutions, methods, techniques, and procedures used in diagnosis and therapy.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.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.DNA Damage: Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Air Pollution: The presence of contaminants or pollutant substances in the air (AIR POLLUTANTS) that interfere with human health or welfare, or produce other harmful environmental effects. The substances may include GASES; PARTICULATE MATTER; or volatile ORGANIC CHEMICALS.Nuclear Magnetic Resonance, Biomolecular: NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.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.Software: Sequential operating programs and data which instruct the functioning of a digital computer.Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Sequence Analysis: A multistage process that includes the determination of a sequence (protein, carbohydrate, etc.), its fragmentation and analysis, and the interpretation of the resulting sequence information.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.Chromatography, Affinity: A chromatographic technique that utilizes the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Lipids: A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)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.Glycosylation: The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Protein Processing, Post-Translational: Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Equipment Design: Methods of creating machines and devices.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.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.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.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)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)Lymphocytes: White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.Cell Line, Tumor: A cell line derived from cultured tumor cells.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.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.Bacterial Proteins: Proteins found in any species of bacterium.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Saccharomyces cerevisiae: A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.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.Oligonucleotide Array Sequence Analysis: Hybridization of a nucleic acid sample to a very large set of OLIGONUCLEOTIDE PROBES, which have been attached individually in columns and rows to a solid support, to determine a BASE SEQUENCE, or to detect variations in a gene sequence, GENE EXPRESSION, or for GENE MAPPING.Computational Biology: A field of biology concerned with the development of techniques for the collection and manipulation of biological data, and the use of such data to make biological discoveries or predictions. This field encompasses all computational methods and theories for solving biological problems including manipulation of models and datasets.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Genetic Variation: Genotypic differences observed among individuals in a population.
Potash: Potash is any of various mined and manufactured salts that contain potassium in water-soluble form.Potash, USGS 2008 Minerals Yearbook The name derives from "pot ash", which refers to plant ashes soaked in water in a pot, the primary means of manufacturing the product before the industrial era.Atomic mass: right |thumb|200px|Stylized [[lithium-7 atom: 3 protons, 4 neutrons, & 3 electrons (total electrons are ~1/4300th of the mass of the nucleus). It has a mass of 7.Electrospray ionizationP-AnisidineUnsaturated hydrocarbon: Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. Those with at least one carbon to carbon double bond are called alkenes and those with at least one carbon to carbon triple bond are called alkynes.Proteomics Standards Initiative: The Proteomics Standards Initiative (PSI) is a working group of Human Proteome Organization. It aims to define data standards for proteomics in order to facilitate data comparison, exchange and verification.Glen Davis Shale Oil Works: The Glen Davis Shale Oil Works was a shale oil extraction plant in Glen Davis, New South Wales, Australia which operated from 1940 until 1952 and was the last oil-shale operation in Australia until the Stuart Oil Shale Project in the late 1990s.Donora Smog Museum: Donora Smog Museum features a collection of archival materials documenting the Donora Smog of 1948, an air inversion of smog containing fluorine that killed 20 people in Donora, Pennsylvania, United States, a mill town 20 miles south of Pittsburgh on the Monongahela River.High-performance liquid chromatography: High-performance liquid chromatography (HPLC; formerly referred to as high-pressure liquid chromatography), is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material.National Offshore Petroleum Safety Authority: The National Offshore Petroleum Safety Authority (NOPSA) was the occupational health and safety (OHS) regulator for the Australian offshore petroleum industry between 2005 and 2011. The role of regulator has been transferred to NOPSEMA - the National Offshore Petroleum Safety and Environmental Management Authority from the first of January 2012.Benzo(k)fluorantheneSealcoat: Sealcoat is a bituminous liquid mixture that is applied to asphalt.Coles PhillipsTandem mass spectrometry: 300 px|right|thumb|A [[Quadrupole mass analyzer|quadrupole time-of-flight hybrid tandem mass spectrometer.]]Benzo(e)pyreneSEA Native Peptide LigationPrinomastatGas chromatography–mass spectrometry: right|300 px|Example of a GC-MS instrument|thumbNational Ambient Air Quality Standards: The National Ambient Air Quality Standards (NAAQS) are standards established by the United States Environmental Protection Agency under authority of the Clean Air Act (42 U.S.Plant Proteome Database: The Plant Proteome Database is a National Science Foundation-funded project to determine the biological function of each protein in plants.Sun Q, Zybailov B, Majeran W, Friso G, Olinares PD, van Wijk KJ.Ammonia volatilization from urea: Urea (46-0-0) accounts for more than fifty percent of the world’s nitrogenous fertilizers.Schwab, G.Soft laser desorption: Soft laser desorption is laser desorption of large molecules that results in ionization without fragmentation. "Soft" in the context of ion formation means forming ions without breaking chemical bonds.Indoor air pollution in developing nations: Indoor air pollution in developing nations is a significant form of indoor air pollution (IAP) that is little known to those in the developed world.Dioxins and dioxin-like compounds: Dioxins and dioxin-like compounds (DLCs) are by-products of various industrial processes, and are commonly regarded as highly toxic compounds that are environmental pollutants and persistent organic pollutants (POPs). They include:ToxicityLattice protein: Lattice proteins are highly simplified computer models of proteins which are used to investigate protein folding.List of Superfund sites in the United States: These are lists of Superfund sites in the United States, designated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. Superfund sites are polluted locations requiring a long-term response to clean up hazardous material contaminations.Nucleoside phosphoramiditeElectron-capture mass spectrometry: Electron-capture mass spectrometry (EC-MS) is a type of mass spectrometry that uses electron capture ionization (ECI) to form negative ions from chemical compounds with positive electron affinities. The approach is particularly effective for electrophiles.Protein primary structure: The primary structure of a peptide or protein is the linear sequence of its amino acid structural units, and partly comprises its overall biomolecular structure. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end.Particulates: Atmospheric particulate matter – also known as particulate matter (PM) or particulates – is microscopic solid or liquid matter suspended in the Earth's atmosphere. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone.Briquette: A briquette (or briquet) is a compressed block of coal dust"briquette, n. 2.Transition metal benzyne complex: Transition metal benzyne complexes are organometallic complexes that contain benzyne ligands (C6H4). Unlike benzyne itself, these complexes are less reactive although they undergo a number of insertion reactions.Carcinogen: A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes.Animals and tobacco smoke: Animals are exposed to tobacco smoke and other cigarette by-products through their use as experimental subjects and through contact with smokers, as in the case of pets in houses where smoking takes place.Xenobiotic: A xenobiotic is a foreign chemical substance found within an organism that is not normally naturally produced by or expected to be present within that organism. It can also cover substances which are present in much higher concentrations than are usual.PhytomedicineBenzofuranSpin–lattice relaxation in the rotating frame: Spin–lattice relaxation in the rotating frame is the mechanism by which Mxy, the transverse component of the magnetization vector, exponentially decays towards its equilibrium value of zero, under the influence of a radio frequency (RF) field in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). It is characterized by the spin–lattice relaxation time constant in the rotating frame, T1ρ.Volumetric heat capacity: Volumetric heat capacity (VHC), also termed volume-specific heat capacity, describes the ability of a given volume of a substance to store internal energy while undergoing a given temperature change, but without undergoing a phase transition. It is different from specific heat capacity in that the VHC is a 'per unit volume' measure of the relationship between thermal energy and temperature of a material, while the specific heat is a 'per unit mass' measure (or occasionally per molar quantity of the material).Eutherian fetoembryonic defense system (eu-FEDS) hypothesis: The Eutherian Fetoembryonic Defense System (eu-FEDS) is a hypothetical model describing a method by which immune systems are capable of recognizing additional states of relatedness like "own species" such as is observed in maternal immune tolerance in pregnancy. The model includes descriptions of the proposed signaling mechanism and several proposed examples of exploitation of this signaling in disease states.Chromatographic response function: Chromatographic response function, often abbreviated to CRF, is a coefficient which measures the quality of the separation in the result of a chromatography.Generalizability theory: Generalizability theory, or G Theory, is a statistical framework for conceptualizing, investigating, and designing reliable observations. It is used to determine the reliability (i.Aerosolization: Aerosolization is the process or act of converting some physical substance into the form of particles small and light enough to be carried on the air i.e.Shape theory of olfaction: The Shape theory of smell proposes that a molecule's smell character is due to its molecular shape, molecular size and functional groups. It has also been described by a 'lock and key' mechanism by which a scent molecule fits into olfactory receptors in the nasal epithelium.Chronic solvent-induced encephalopathy: Chronic solvent induced encephalopathy (CSE) is a condition induced by long-term exposure to organic solvents, typically in the workplace, that lead to a wide variety of persisting sensorimotor polyneuropathies and neurobehavioral deficits even after solvent exposure has been removed. This syndrome can also be referred to as "psycho-organic syndrome", "organic solvent syndrome", "chronic painter's syndrome", "occupational solvent encephalopathy", "solvent intoxication", "toxic solvent syndrome", "painters disease", "psycho-organic syndrome", "chronic toxic encephalopathy", and "neurasthenic syndrome".Beef cattle: Beef cattle are cattle raised for meat production (as distinguished from dairy cattle, used for milk production). The meat of adult cattle is known as beef.Mutagen: In genetics, a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer, mutagens are therefore also likely to be carcinogens.N-linked glycosylation: N-linked glycosylation, is the attachment of the sugar molecule oligosaccharide known as glycan to a nitrogen atom (amide nitrogen of asparagine (Asn) residue of a protein), in a process called N-glycosylation, studied in biochemistry. This type of linkage is important for both the structure and function of some eukaryotic proteins.Exhaust gasCoulter counter: 150px|thumb|right|The tip of the Coulter counter in a buffer solution, counting cells in solution.Occupational hygiene: Occupational (or "industrial" in the U.S.Metabolomics: Metabolomics is the scientific study of chemical processes involving metabolites. Specifically, metabolomics is the "systematic study of the unique chemical fingerprints that specific cellular processes leave behind", the study of their small-molecule metabolite profiles.Mineral dust: Mineral dust is a term used to indicate atmospheric aerosols originated from the suspension of minerals constituting the soil, being composed of various oxides and carbonates. Human activities lead to 30% of the dust load in the atmosphere.Assay sensitivity: Assay sensitivity is a property of a clinical trial defined as the ability of a trial to distinguish an effective treatment from a less effective or ineffective intervention. Without assay sensitivity, a trial is not internally valid and is not capable of comparing the efficacy of two interventions.Biotransformation: Biotransformation is the chemical modification (or modifications) made by an organism on a chemical compound. If this modification ends in mineral compounds like CO2, NH4+, or H2O, the biotransformation is called mineralisation.Proteinogenic amino acid: Proteinogenic amino acids are amino acids that are precursors to proteins, and are incorporated into proteins cotranslationally — that is, during translation. There are 23 proteinogenic amino acids in prokaryotes (including N-Formylmethionine, mainly used to initiate protein synthesis and often removed afterward), but only 21 are encoded by the nuclear genes of eukaryotes.Smokefree Environments Amendment Act 2003: The Smokefree Environments Amendment Bill was passed by the Parliament of New Zealand on 3 December 2003. The smoking ban legislation calls for progressive introduction of various clauses to totally ban smoking in all workplaces including offices, clubs, pubs, restaurants, airports, schools etc.Isotope-coded affinity tag: An Isotope-coded affinity tag (ICAT) is an isotopic labeling method used for quantitative proteomics by mass spectrometry that uses chemical labeling reagents. "Rapid quantitative analysis of proteins or protein function in complex mixtures," Rudolf Hans Aebersold et al.ForskolinDrug interaction: A drug interaction is a situation in which a substance (usually another drug) affects the activity of a drug when both are administered together. This action can be synergistic (when the drug's effect is increased) or antagonistic (when the drug's effect is decreased) or a new effect can be produced that neither produces on its own.Symmetry element: A symmetry element is a point of reference about which symmetry operations can take place. In particular, symmetry elements can be centers of inversion, axes of rotation and mirror planes.Margaret Jope: Margaret Jope (1913–2004) was a Scottish biochemist, born as Henrietta Margaret Halliday in Peterhead, Scotland.Isomerization: In chemistry isomerization (also isomerisation) is the process by which one molecule is transformed into another molecule which has exactly the same atoms, but the atoms have a different arrangement e.g.Concentration effect: In the study of inhaled anesthetics, the concentration effect is the increase in the rate that the Fa(alveolar concentration)/Fi(inspired concentration) ratio rises as the alveolar concentration of that gas is increased. In simple terms, the higher the concentration of gas administered, the faster the alveolar concentration of that gas approaches the inspired concentration.Clonal Selection Algorithm: In artificial immune systems, Clonal selection algorithms are a class of algorithms inspired by the clonal selection theory of acquired immunity that explains how B and T lymphocytes improve their response to antigens over time called affinity maturation. These algorithms focus on the Darwinian attributes of the theory where selection is inspired by the affinity of antigen-antibody interactions, reproduction is inspired by cell division, and variation is inspired by somatic hypermutation.History of nanotechnology: The history of nanotechnology traces the development of the concepts and experimental work falling under the broad category of nanotechnology. Although nanotechnology is a relatively recent development in scientific research, the development of its central concepts happened over a longer period of time.Molar mass distribution: In linear polymers the individual polymer chains rarely have exactly the same degree of polymerization and molar mass, and there is always a distribution around an average value. The molar mass distribution (or molecular weight distribution) in a polymer describes the relationship between the number of moles of each polymer species (Ni) and the molar mass (Mi) of that species.Burst kinetics: Burst kinetics is a form of enzyme kinetics that refers to an initial high velocity of enzymatic turnover when adding enzyme to substrate. This initial period of high velocity product formation is referred to as the "Burst Phase".DNA condensation: DNA condensation refers to the process of compacting DNA molecules in vitro or in vivo. Mechanistic details of DNA packing are essential for its functioning in the process of gene regulation in living systems.Diffuse reflectance infrared fourier transform: Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS)C.-P.
(1/369) Cell death during corneal storage at 4 degrees C.
PURPOSE: To evaluate cell death in human donor corneas stored at 4 degrees C, to determine whether terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick-end labeling (TUNEL) discriminates between apoptosis and necrosis in corneas stored at 4 degrees C. METHODS: Ten human corneas were stored in Optisol (Chiron Ophthalmics, Irvine, CA) at 4 degrees C for periods ranging from 0 to 21 days and then fixed for histologic examination. Central corneal sections from each cornea were examined by transmission electron microscopy (TEM) and by the TUNEL assay. Electron micrographs of at least 15 keratocytes each from the anterior, middle, and posterior stroma were examined by three masked observers who graded each cell as normal, apoptotic, or necrotic. Central sections from the same corneas were processed by the TUNEL assay and evaluated with a laser scanning confocal microscope to determine the percentage of apoptotic cells. RESULTS: By TEM, apoptosis occurred in 23% of the keratocytes and necrosis in 12%. By TUNEL assay, apoptosis occurred in 11% of the keratocytes, with the results in individual corneas being similar to the findings by TEM for apoptosis, rather than for necrosis. By TUNEL assay, apoptosis occurred in 13% of the epithelial cells and in 8% of the endothelial cells. The percentage of apoptotic cells and storage time correlated significantly for the epithelium, but not for the keratocytes or endothelium in this small sample. CONCLUSIONS: Both apoptosis and necrosis occur in cells during corneal storage at 4 degrees C, with apoptosis appearing to predominate. The TUNEL assay identifies cells undergoing apoptosis, but not necrosis, in corneal tissue. Inhibition of apoptosis in corneas stored at 4 degrees C may prolong acceptable storage times. (+info)
(2/369) Effectiveness of microabrasion technique for improvement of dental aesthetics.
OBJECTIVES: To investigate which types of enamel opacity are effectively treated by the microabrasion technique and whether this technique could be used as a diagnostic aid to determine the aetiology of these defects. MATERIALS AND METHOD: Thirty two patients who had enamel opacities affecting both upper central incisors were selected and the disfigurements were classified into four types: single line, multi-line, patched and diffused. The patient's previous medical history, possible history of fluoride ingestion, presence of taurodontism and family history of similar enamel defects were recorded. Both incisors were treated with Prema abrasive paste mixed with 18% hydrochloric acid. The aesthetic improvements were assessed by the patients and their parents and their satisfaction level after the treatment was recorded. RESULTS: Approximately two-thirds (65.6%) of the patients were satisfied with their appearance after microabrasion. Apart from four patients, the improved appearance was stable and acceptable to the remaining patients at the six month recall. Statistical analysis showed that acceptable improvement was found in patients with single line/patched types of defects but not in multi-line/diffused types (P = 0.03). However, the aesthetic improvement was not related to the patient's fluoride history, presence of taurodontism or the family history of enamel defects. CONCLUSION: Microabrasion using Prema abrasives with 1 8% HCI is effective in improving the appearance of enamel with single-line or patched opacities, indicating that these defects are a surface phenomenon. For the multi-line and diffused types, the defects appear to extend deeper into the enamel. The technique failed to assist in determining the aetiology of these defects. (+info)
(3/369) GFS, a preparation of Tasmanian Undaria pinnatifida is associated with healing and inhibition of reactivation of Herpes.
BACKGROUND: We sought to assess whether GFS, a proprietary preparation of Tasmanian Undaria pinnatifida, has effects on healing or re-emergence of Herpetic infections, and additionally, to assess effects of GFS in vitro. Undaria is the most commonly eaten seaweed in Japan, and contains sulphated polyanions and other components with potential anti-viral activity. Herpes simplex virus type 1 (HSV-1) infections have lower reactivation rates and Herpes type 2 (HSV-2) infections have lower incidence in Japan than in the west. METHODS: Patients with active (15 subjects) or latent (6 subjects) Herpetic infections (HSV-1, 2, EBV, Zoster) were monitored for response to ingestion of GFS. GFS extract was tested in vitro for human T cell mitogenicity and anti-Herpes activity. RESULTS: Ingestion of GFS was associated with increased healing rates in patients with active infections. In addition, patients with latent infection remained asymptomatic whilst ingesting GFS. GFS extract inhibited Herpes viruses in vitro and was mitogenic to human T cells in vitro. CONCLUSIONS: Ingestion of GFS has inhibitory effects on reactivation and is associated with increased rate of healing after Herpetic outbreaks. GFS extract potently inhibited Herpes virus in vitro, and had mitogenic effects on human T cells. (+info)
(4/369) The use of antimicrobial peptides in ophthalmology: an experimental study in corneal preservation and the management of bacterial keratitis.
PURPOSE: Bacterial keratitis is an ocular infection with the potential to cause significant visual impairment. Increasing patterns of antibiotic resistance have necessitated the development of new antimicrobial agents for use in bacterial keratitis and other serious ocular infections. With a view to exploring the use of novel antimicrobial peptides in the management of ocular infection, we performed a series of experiments using synthetic antimicrobial peptides designed for the eradication of common and serious ophthalmic pathogens. METHODS: Experiments were performed with three clinical ocular isolates--Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis--in three experimental settings: (1) in vitro in a controlled system of 10 mM sodium phosphate buffer, (2) in vitro in modified chondroitin sulfate-based corneal preservation media (Optisol), and (3) in an in vivo animal model (rabbit) simulating bacterial keratitis. In all cases, outcomes were measured by quantitative microbiological techniques. RESULTS: The candidate peptides (CCI A, B, and C and COL-1) produced a total reduction of the test pathogens in phosphate buffered saline. In modified Optisol, the peptides were effective against S epidermidis at all temperatures, demonstrated augmented activity at 23 degrees C against the gram-positive organisms, but were ineffective against P aeruginosa. The addition of EDTA to the medium augmented the killing of P aeruginosa but made no difference in the reduction of gram-positive organisms. In an in vivo rabbit model of Pseudomonas keratitis, COL-1 demonstrated neither clinical nor microbicidal efficacy and appeared to have a very narrow dosage range, outside of which it appeared to be toxic to the ocular surface. CONCLUSION: Our data indicate that the antimicrobial peptides we tested were effective in vitro but not in vivo. In an age of increasing antibiotic resistance, antimicrobial peptides, developed over millions of years as innate defense mechanisms by plants and animals, may have significant potential for development as topical agents for the management of severe bacterial keratitis. However, modifications of the peptides, the drug delivery systems, or both, will be necessary for effective clinical application. (+info)
(5/369) Crude extracts of bacterially expressed dsRNA can be used to protect plants against virus infections.
BACKGROUND: Double-stranded RNA (dsRNA) is a potent initiator of gene silencing in a diverse group of organisms that includes plants, Caenorhabditis elegans, Drosophila and mammals. We have previously shown and patented that mechanical inoculation of in vitro-transcribed dsRNA derived from viral sequences specifically prevents virus infection in plants. The approach required the in vitro synthesis of large amounts of RNA involving high cost and considerable labour. RESULTS: We have developed an in vivo expression system to produce large amounts of virus-derived dsRNAs in bacteria, with a view to providing a practical control of virus diseases in plants. Partially purified bacterial dsRNAs promoted specific interference with the infection in plants by two viruses belonging to the tobamovirus and potyvirus groups. Furthermore, we have demonstrated that easy to obtain, crude extracts of bacterially expressed dsRNAs are equally effective protecting plants against virus infections when sprayed onto plant surfaces by a simple procedure. Virus infectivity was significantly abolished when plants were sprayed with French Press lysates several days before virus inoculation. CONCLUSION: Our approach provides an alternative to genetic transformation of plant species with dsRNA-expressing constructs capable to interfere with plant viruses. The main advantage of this mode of dsRNA production is its simplicity and its extremely low cost compared with the requirements for regenerating transgenic plants. This approach provides a reliable and potential tool, not only for plant protection against virus diseases, but also for the study of gene silencing mechanisms in plant virus infections. (+info)
(6/369) Protein stability in mixed solvents: a balance of contact interaction and excluded volume.
Changes in excluded volume and contact interaction with the surface of a protein have been suggested as mechanisms for the changes in stability induced by cosolvents. The aim of the present paper is to present an analysis that combines both effects in a quantitative manner. The result is that both processes are present in both stabilizing and destabilizing interactions and neither can be ignored. Excluded volume was estimated using accessible surface area calculations of the kind introduced by Lee and Richards. The change in excluded volume on unfolding, deltaX, is quite large. For example, deltaX for ribonuclease is 6.7 L in urea and approximately 16 L in sucrose. The latter number is greater than the molar volume of the protein. Direct interaction with the protein is represented as the solvent exchange mechanism, which differs from ordinary association theory because of the weakness of the interaction and the high concentrations of cosolvents. The balance between the two effects and their contribution to overall stability are most simply presented as bar diagrams as in Fig. 3. Our finding for five proteins is that excluded volume contributes to the stabilization of the native structure and that contact interaction contributes to destabilization. This is true for five proteins and four cosolvents including both denaturants and osmolytes. Whether a substance stabilizes a protein or destabilizes it depends on the relative size of these two contributions. The constant for the cosolvent contact with the protein is remarkably uniform for four of the proteins, indicating a similarity of groups exposed during unfolding. One protein, staphylococcus nuclease, is anomalous in almost all respects. In general, the strength of the interaction with guanidinium is about twice that of urea, which is about twice that of trimethylamine-N-oxide and sucrose. Arguments are presented for the use of volume fractions in equilibrium equations and the ignoring of activity coefficients of the cosolvent. It is shown in the Appendix that both the excluded volume and the direct interaction can be extracted in a unified way from the McMillan-Mayer formula for the second virial coefficient. (+info)
(7/369) Solvation of nucleosides in aqueous mixtures of organic solvents: relevance to DNA open basepairs.
Toward the goal of understanding how open basepairs in DNA interact with their heterogeneous environment, we have studied the steady-state intrinsic fluorescence properties of the purine and pyrimidine deoxynucleosides in organic solvents in the presence of small amounts of water. The organic solvents used in the present study were: n-butanol, acetonitrile, methanol, n-propanol, isopropanol, and isobutanol. For n-butanol and acetonitrile, which have a high degree of amphiphilicity and weak hydrogen bonding ability, respectively, the fluorescence spectral properties of the purines are found to depend on the sequence of steps in which the aqueous mixtures were formed. By contrast, no such dependence was observed in the mixtures with any of the other solvents used in the present study. Moreover, no such dependence was observed for the pyrimidines. These findings suggest that the final solvation network around the purines is dependent on the nature of the environment to which they were initially exposed. This would tend to present an impediment to the closing of AT or GC basepairs in DNA that become open as a result of structural fluctuations, DNA bending, or protein-DNA interactions. (+info)
(8/369) Egg hatching, larval movement and larval survival of the malaria vector Anopheles gambiae in desiccating habitats.
BACKGROUND: Although the effects of rainfall on the population dynamics of the malaria vector Anopheles gambiae have been studied in great detail, the effects of dry periods on its survival remain less clear. METHODS: The effects of drying conditions were simulated by creating desiccated habitats, which consisted of trays filled with damp soil. Experiments were performed in these trays to (i) test the ability of An. gambiae sensu stricto eggs to hatch on damp soil and for larvae to reach an artificial breeding site at different distances of the site of hatching and (ii) to record survival of the four larval stages of An. gambiae s.s. when placed on damp soil. RESULTS: Eggs of An. gambiae s.s. hatched on damp soil and emerging larvae were capable of covering a distance of up to 10 cm to reach surface water enabling further development. However, proportions of larvae reaching the site decreased rapidly with increasing distance. First, second and third-instar larvae survived on damp soil for an estimated period of 64, 65 and 69 hrs, respectively. Fourth-instar larvae survived significantly longer and we estimated that the maximum survival time was 113 hrs. CONCLUSION: Short-term survival of aquatic stages of An. gambiae on wet soil may be important and adaptive when considering the transient nature of breeding sites of this species in sub-Saharan Africa. In addition, the results suggest that, for larval vector control methods to be effective, habitats should remain drained for at least 5 days to kill all larvae (e.g. in rice fields) and habitats that recently dried up should be treated as well, if larvicidal agents are applied. (+info)