Electrophoresis in which various denaturant gradients are used to induce nucleic acids to melt at various stages resulting in separation of molecules based on small sequence differences including SNPs. The denaturants used include heat, formamide, and urea.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current.

Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.

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.

Electrophoresis in which agar or agarose gel is used as the diffusion medium.

DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.

Deoxyribonucleic acid that makes up the genetic material of bacteria.

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.

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.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.

The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.

Gel electrophoresis in which the direction of the electric field is changed periodically. This technique is similar to other electrophoretic methods normally used to separate double-stranded DNA molecules ranging in size up to tens of thousands of base-pairs. However, by alternating the electric field direction one is able to separate DNA molecules up to several million base-pairs in length.

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.

A technique for identifying individuals of a species that is based on the uniqueness of their DNA sequence. Uniqueness is determined by identifying which combination of allelic variations occur in the individual at a statistically relevant number of different loci. In forensic studies, RESTRICTION FRAGMENT LENGTH POLYMORPHISM of multiple, highly polymorphic VNTR LOCI or MICROSATELLITE REPEAT loci are analyzed. The number of loci used for the profile depends on the ALLELE FREQUENCY in the population.

Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.

The variety of all native living organisms and their various forms and interrelationships.

A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)

The relationships of groups of organisms as reflected by their genetic makeup.

The sum of the weight of all the atoms in a molecule.

Water containing no significant amounts of salts, such as water from RIVERS and LAKES.

A highly-sensitive (in the picomolar range, which is 10,000-fold more sensitive than conventional electrophoresis) and efficient technique that allows separation of PROTEINS; NUCLEIC ACIDS; and CARBOHYDRATES. (Segen, Dictionary of Modern Medicine, 1992)

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

A class in the phylum PROTEOBACTERIA comprised of chemoheterotrophs and chemoautotrophs which derive nutrients from decomposition of organic material.

Genes, found in both prokaryotes and eukaryotes, which are transcribed to produce the RNA which is incorporated into RIBOSOMES. Prokaryotic rRNA genes are usually found in OPERONS dispersed throughout the GENOME, whereas eukaryotic rRNA genes are clustered, multicistronic transcriptional units.

The spectrum of different living organisms inhabiting a particular region, habitat, or biotope.

The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.

Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.

Community of tiny aquatic PLANTS and ANIMALS, and photosynthetic BACTERIA, that are either free-floating or suspended in the water, with little or no power of locomotion. They are divided into PHYTOPLANKTON and ZOOPLANKTON.

Elimination of ENVIRONMENTAL POLLUTANTS; PESTICIDES and other waste using living organisms, usually involving intervention of environmental or sanitation engineers.

A phylum of bacteria consisting of the purple bacteria and their relatives which form a branch of the eubacterial tree. This group of predominantly gram-negative bacteria is classified based on homology of equivalent nucleotide sequences of 16S ribosomal RNA or by hybridization of ribosomal RNA or DNA with 16S and 23S ribosomal RNA.

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.

Tools or devices for generating products using the synthetic or chemical conversion capacity of a biological system. They can be classical fermentors, cell culture perfusion systems, or enzyme bioreactors. For production of proteins or enzymes, recombinant microorganisms such as bacteria, mammalian cells, or insect or plant cells are usually chosen.

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)

A set of statistical methods used to group variables or observations into strongly inter-related subgroups. In epidemiology, it may be used to analyze a closely grouped series of events or cases of disease or other health-related phenomenon with well-defined distribution patterns in relation to time or place or both.

A genus of gram-positive, microaerophilic, rod-shaped bacteria occurring widely in nature. Its species are also part of the many normal flora of the mouth, intestinal tract, and vagina of many mammals, including humans. Pathogenicity from this genus is rare.

Relating to the size of solids.

Electrophoresis applied to BLOOD PROTEINS.

A group of different species of microorganisms that act together as a community.

A selective pre- and post-emergence herbicide. (From Merck Index, 11th ed)

The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.

A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)

A collective genome representative of the many organisms, primarily microorganisms, existing in a community.

Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.

Low-density subclass of the high-density lipoproteins, with particle sizes between 8 to 13 nm.

A genus of gram-negative, ellipsoidal or rod-shaped bacteria whose major source of energy and reducing power is from the oxidation of ammonia to nitrite. Its species occur in soils, oceans, lakes, rivers, and sewage disposal systems.

One of the three domains of life (the others being BACTERIA and Eukarya), formerly called Archaebacteria under the taxon Bacteria, but now considered separate and distinct. They are characterized by: (1) the presence of characteristic tRNAs and ribosomal RNAs; (2) the absence of peptidoglycan cell walls; (3) the presence of ether-linked lipids built from branched-chain subunits; and (4) their occurrence in unusual habitats. While archaea resemble bacteria in morphology and genomic organization, they resemble eukarya in their method of genomic replication. The domain contains at least four kingdoms: CRENARCHAEOTA; EURYARCHAEOTA; NANOARCHAEOTA; and KORARCHAEOTA.

Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.

A nutritious food consisting primarily of the curd or the semisolid substance formed when milk coagulates.

Intermediate-density subclass of the high-density lipoproteins, with particle sizes between 7 to 8 nm. As the larger lighter HDL2 lipoprotein, HDL3 lipoprotein is lipid-rich.

Naturally occurring complex liquid hydrocarbons which, after distillation, yield combustible fuels, petrochemicals, and lubricants.

A group of gram-negative, anaerobic bacteria that is able to oxidize acetate completely to carbon dioxide using elemental sulfur as the electron acceptor.

A plant family of the order Rhizophorales, subclass Rosidae, class Magnoliopsida, that includes mangrove trees.

A class of lipoproteins of small size (4-13 nm) and dense (greater than 1.063 g/ml) particles. HDL lipoproteins, synthesized in the liver without a lipid core, accumulate cholesterol esters from peripheral tissues and transport them to the liver for re-utilization or elimination from the body (the reverse cholesterol transport). Their major protein component is APOLIPOPROTEIN A-I. HDL also shuttle APOLIPOPROTEINS C and APOLIPOPROTEINS E to and from triglyceride-rich lipoproteins during their catabolism. HDL plasma level has been inversely correlated with the risk of cardiovascular diseases.

Constituent of the 40S subunit of eukaryotic ribosomes. 18S rRNA is involved in the initiation of polypeptide synthesis in eukaryotes.

The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.

The discarding or destroying of liquid waste products or their transformation into something useful or innocuous.

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.

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.

Substances which pollute the soil. Use for soil pollutants in general or for which there is no specific heading.

Genotypic differences observed among individuals in a population.

Biochemical identification of mutational changes in a nucleotide sequence.

Procedures for identifying types and strains of bacteria. The most frequently employed typing systems are BACTERIOPHAGE TYPING and SEROTYPING as well as bacteriocin typing and biotyping.

A rod-shaped, gram-positive, non-acid-fast, non-spore-forming, non-motile bacterium that is a genus of the family Bifidobacteriaceae, order Bifidobacteriales, class ACTINOBACTERIA. It inhabits the intestines and feces of humans as well as the human vagina.

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.

The immediate physical zone surrounding plant roots that include the plant roots. It is an area of intense and complex biological activity involving plants, microorganisms, other soil organisms, and the soil.

The study of microorganisms living in a variety of environments (air, soil, water, etc.) and their pathogenic relationship to other organisms including man.

A plant family of the order Myrtales, subclass Rosidae, class Magnoliopsida. They are mostly trees and shrubs growing in warm areas.

Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.

Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point.

The rate dynamics in chemical or physical systems.

Refuse liquid or waste matter carried off by sewers.

The simplest saturated hydrocarbon. It is a colorless, flammable gas, slightly soluble in water. It is one of the chief constituents of natural gas and is formed in the decomposition of organic matter. (Grant & Hackh's Chemical Dictionary, 5th ed)

A family of gram-positive non-sporing bacteria including many parasitic, pathogenic, and saprophytic forms.

Centrifugation with a centrifuge that develops centrifugal fields of more than 100,000 times gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).

The 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)

Any of several processes in which undesirable impurities in water are removed or neutralized; for example, chlorination, filtration, primary treatment, ion exchange, and distillation. It includes treatment of WASTE WATER to provide potable and hygienic water in a controlled or closed environment as well as provision of public drinking water supplies.

A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.

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.

Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).

Areas of the earth where hydrocarbon deposits of PETROLEUM and/or NATURAL GAS are located.

A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.

Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment.

A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.

An order of anaerobic methanogens in the kingdom EURYARCHAEOTA. There are two families: METHANOSARCINACEAE and Methanosaetaceae.

Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.

Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones.

Adverse effect upon bodies of water (LAKES; RIVERS; seas; groundwater etc.) caused by CHEMICAL WATER POLLUTANTS.

Proteins found in any species of bacterium.

A group of the proteobacteria comprised of facultatively anaerobic and fermentative gram-negative bacteria.

Electrophoresis in which a starch gel (a mixture of amylose and amylopectin) is used as the diffusion medium.

Deoxyribonucleic acid that makes up the genetic material of archaea.

The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA.

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)

Protein components on the surface of LIPOPROTEINS. They form a layer surrounding the hydrophobic lipid core. There are several classes of apolipoproteins with each playing a different role in lipid transport and LIPID METABOLISM. These proteins are synthesized mainly in the LIVER and the INTESTINES.

Class of BACTERIA with diverse morphological properties. Strains of Actinobacteria show greater than 80% 16S rDNA/rRNA sequence similarity among each other and also the presence of certain signature nucleotides. (Stackebrandt E. et al, Int. J. Syst. Bacteriol. (1997) 47:479-491)

Generally refers to the digestive structures stretching from the MOUTH to ANUS, but does not include the accessory glandular organs (LIVER; BILIARY TRACT; PANCREAS).

The phylum of sponges which are sessile, suspension-feeding, multicellular animals that utilize flagellated cells called choanocytes to circulate water. Most are hermaphroditic. They are probably an early evolutionary side branch that gave rise to no other group of animals. Except for about 150 freshwater species, sponges are marine animals. They are a source of ALKALOIDS; STEROLS; and other complex molecules useful in medicine and biological research.

A family of gram-positive bacteria found regularly in the mouth and intestinal tract of man and other animals, in food and dairy products, and in fermenting vegetable juices. A few species are highly pathogenic.

A highly miniaturized version of ELECTROPHORESIS performed in a microfluidic device.

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.

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.

Technique that utilizes low-stringency polymerase chain reaction (PCR) amplification with single primers of arbitrary sequence to generate strain-specific arrays of anonymous DNA fragments. RAPD technique may be used to determine taxonomic identity, assess kinship relationships, analyze mixed genome samples, and create specific probes.

The most abundant protein component of HIGH DENSITY LIPOPROTEINS or HDL. This protein serves as an acceptor for CHOLESTEROL released from cells thus promoting efflux of cholesterol to HDL then to the LIVER for excretion from the body (reverse cholesterol transport). It also acts as a cofactor for LECITHIN CHOLESTEROL ACYLTRANSFERASE that forms CHOLESTEROL ESTERS on the HDL particles. Mutations of this gene APOA1 cause HDL deficiency, such as in FAMILIAL ALPHA LIPOPROTEIN DEFICIENCY DISEASE and in some patients with TANGIER DISEASE.

One of the three domains of life (the others being BACTERIA and ARCHAEA), also called Eukarya. These are organisms whose cells are enclosed in membranes and possess a nucleus. They comprise almost all multicellular and many unicellular organisms, and are traditionally divided into groups (sometimes called kingdoms) including ANIMALS; PLANTS; FUNGI; and various algae and other taxa that were previously part of the old kingdom Protista.

A phylum of bacteria comprised of three classes: Bacteroides, Flavobacteria, and Sphingobacteria.

Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.

Deoxyribonucleic acid that makes up the genetic material of fungi.

Using MOLECULAR BIOLOGY techniques, such as DNA SEQUENCE ANALYSIS; PULSED-FIELD GEL ELECTROPHORESIS; and DNA FINGERPRINTING, to identify, classify, and compare organisms and their subtypes.

The measurement of the density of a material by measuring the amount of light or radiation passing through (or absorbed by) the material.

Presence of warmth or heat or a temperature notably higher than an accustomed norm.

The presence of bacteria, viruses, and fungi in food and food products. This term is not restricted to pathogenic organisms: the presence of various non-pathogenic bacteria and fungi in cheeses and wines, for example, is included in this concept.

A plant species of the genus CHRYSANTHEMUM, family ASTERACEAE. The flowers contain PYRETHRINS, cinerolones, and chrysanthemines which are powerful contact insecticides. Most in the old Pyrethrum genus are reclassified to TANACETUM; some to other ASTERACEAE genera.

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).

A large group of bacteria including those which oxidize ammonia or nitrite, metabolize sulfur and sulfur compounds, or deposit iron and/or manganese oxides.

A mutation caused by the substitution of one nucleotide for another. This results in the DNA molecule having a change in a single base pair.

Infections with BACTERIA of the order Bifidobacteriales. This includes infections in the genera BIFIDOBACTERIUM and GARDNERELLA, in the family Bifidobacteriaceae.

The pH in solutions of proteins and related compounds at which the dipolar ions are at a maximum.

Structural proteins of the alpha-lipoproteins (HIGH DENSITY LIPOPROTEINS), including APOLIPOPROTEIN A-I and APOLIPOPROTEIN A-II. They can modulate the activity of LECITHIN CHOLESTEROL ACYLTRANSFERASE. These apolipoproteins are low in atherosclerotic patients. They are either absent or present in extremely low plasma concentration in TANGIER DISEASE.

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.

A genus of motile or nonmotile gram-positive bacteria of the family Clostridiaceae. Many species have been identified with some being pathogenic. They occur in water, soil, and in the intestinal tract of humans and lower animals.

A thin-walled distention of the alimentary tract protruding just outside the body cavity in the distal end of the neck (esophagus), used for the temporary storage of food and water.

Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.

Progressive, autosomal recessive, diffuse atrophy of the choroid, pigment epithelium, and sensory retina that begins in childhood.

A process facilitated by specialized bacteria involving the oxidation of ammonium to nitrite and nitrate.

Phylum of green nonsulfur bacteria including the family Chloroflexaceae, among others.

The full collection of microbes (bacteria, fungi, virus, etc.) that naturally exist within a particular biological niche such as an organism, soil, a body of water, etc.

Cultivation of natural faunal resources of water. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A class in the phylum PROTEOBACTERIA comprised mostly of two major phenotypes: purple non-sulfur bacteria and aerobic bacteriochlorophyll-containing bacteria.

The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)

The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.

RESTRICTION FRAGMENT LENGTH POLYMORPHISM analysis of rRNA genes that is used for differentiating between species or strains.

Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.

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)

The intergenic DNA segments that are between the ribosomal RNA genes (internal transcribed spacers) and between the tandemly repeated units of rDNA (external transcribed spacers and nontranscribed spacers).

A phylum of oxygenic photosynthetic bacteria comprised of unicellular to multicellular bacteria possessing CHLOROPHYLL a and carrying out oxygenic PHOTOSYNTHESIS. Cyanobacteria are the only known organisms capable of fixing both CARBON DIOXIDE (in the presence of light) and NITROGEN. Cell morphology can include nitrogen-fixing heterocysts and/or resting cells called akinetes. Formerly called blue-green algae, cyanobacteria were traditionally treated as ALGAE.

Chemical groups containing the covalent sulfur bonds -S-. The sulfur atom can be bound to inorganic or organic moieties.

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.

Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.

The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.

Inorganic salts of sulfuric acid.

Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.

Aerobic bacteria are types of microbes that require oxygen to grow and reproduce, and use it in the process of respiration to break down organic matter and produce energy, often found in environments where oxygen is readily available such as the human body's skin, mouth, and intestines.

An anionic surfactant, usually a mixture of sodium alkyl sulfates, mainly the lauryl; lowers surface tension of aqueous solutions; used as fat emulsifier, wetting agent, detergent in cosmetics, pharmaceuticals and toothpastes; also as research tool in protein biochemistry.

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.

Encrustations, formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedding in extracellular polymers, that adhere to surfaces such as teeth (DENTAL DEPOSITS); PROSTHESES AND IMPLANTS; and catheters. Biofilms are prevented from forming by treating surfaces with DENTIFRICES; DISINFECTANTS; ANTI-INFECTIVE AGENTS; and antifouling agents.

'Anaerobic Bacteria' are types of bacteria that do not require oxygen for growth and can often cause diseases in humans, including dental caries, gas gangrene, and tetanus, among others.

The functional hereditary units of BACTERIA.

The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)

Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.

Articles of food which are derived by a process of manufacture from any portion of carcasses of any animal used for food (e.g., head cheese, sausage, scrapple).

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.

A family of gram-negative aerobic bacteria in the class BETA PROTEOBACTERIA, encompassing the acidovorans rRNA complex. Some species are pathogenic for PLANTS.

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.

Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.

The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.

The continent lying around the South Pole and the southern waters of the Atlantic, Pacific, and Indian Oceans. It includes the Falkland Islands Dependencies. (From Webster's New Geographical Dictionary, 1988, p55)

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.

Transport proteins that carry specific substances in the blood or across cell membranes.

The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.

Major structural proteins of triacylglycerol-rich LIPOPROTEINS. There are two forms, apolipoprotein B-100 and apolipoprotein B-48, both derived from a single gene. ApoB-100 expressed in the liver is found in low-density lipoproteins (LIPOPROTEINS, LDL; LIPOPROTEINS, VLDL). ApoB-48 expressed in the intestine is found in CHYLOMICRONS. They are important in the biosynthesis, transport, and metabolism of triacylglycerol-rich lipoproteins. Plasma Apo-B levels are high in atherosclerotic patients but non-detectable in ABETALIPOPROTEINEMIA.

Electrophoresis in which cellulose acetate is the diffusion medium.

Baked food product made of flour or meal that is moistened, kneaded, and sometimes fermented. A major food since prehistoric times, it has been made in various forms using a variety of ingredients and methods.

A genus of gram-positive bacteria in the family Lachnospiraceae that inhabits the RUMEN; LARGE INTESTINE; and CECUM of MAMMALS.

Live microbial DIETARY SUPPLEMENTS which beneficially affect the host animal by improving its intestinal microbial balance. Antibiotics and other related compounds are not included in this definition. In humans, lactobacilli are commonly used as probiotics, either as single species or in mixed culture with other bacteria. Other genera that have been used are bifidobacteria and streptococci. (J. Nutr. 1995;125:1401-12)

The blind sac or outpouching area of the LARGE INTESTINE that is below the entrance of the SMALL INTESTINE. It has a worm-like extension, the vermiform APPENDIX.

The systematic study of the complete complement of proteins (PROTEOME) of organisms.

Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)

Substances or mixtures that are added to the soil to supply nutrients or to make available nutrients already present in the soil, in order to increase plant growth and productivity.

The study of the origin, structure, development, growth, function, genetics, and reproduction of organisms which inhabit the OCEANS AND SEAS.

Contaminated water generated as a waste product of human activity.

A genus of gram-negative, anaerobic, rod-shaped bacteria. Its organisms are normal inhabitants of the oral, respiratory, intestinal, and urogenital cavities of humans, animals, and insects. Some species may be pathogenic.

Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).

A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.

A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.

A plant genus of the family POACEAE that is the source of EDIBLE GRAIN. A hybrid with rye (SECALE CEREALE) is called TRITICALE. The seed is ground into FLOUR and used to make BREAD, and is the source of WHEAT GERM AGGLUTININS.

A genus of gram-negative, aerobic, rod-shaped bacteria widely distributed in nature. Some species are pathogenic for humans, animals, and plants.

A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.

A genus of gram-negative, aerobic, rod-shaped bacteria characterized by an outer membrane that contains glycosphingolipids but lacks lipopolysaccharide. They have the ability to degrade a broad range of substituted aromatic compounds.

The protein complement of an organism coded for by its genome.

Accumulations of solid or liquid animal excreta usually from stables and barnyards with or without litter material. Its chief application is as a fertilizer. (From Webster's 3d ed)

A large family of narrow-leaved herbaceous grasses of the order Cyperales, subclass Commelinidae, class Liliopsida (monocotyledons). Food grains (EDIBLE GRAIN) come from members of this family. RHINITIS, ALLERGIC, SEASONAL can be induced by POLLEN of many of the grasses.

Elements of limited time intervals, contributing to particular results or situations.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

The first stomach of ruminants. It lies on the left side of the body, occupying the whole of the left side of the abdomen and even stretching across the median plane of the body to the right side. It is capacious, divided into an upper and a lower sac, each of which has a blind sac at its posterior extremity. The rumen is lined by mucous membrane containing no digestive glands, but mucus-secreting glands are present in large numbers. Coarse, partially chewed food is stored and churned in the rumen until the animal finds circumstances convenient for rumination. When this occurs, little balls of food are regurgitated through the esophagus into the mouth, and are subjected to a second more thorough mastication, swallowed, and passed on into other parts of the compound stomach. (From Black's Veterinary Dictionary, 17th ed)

The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.

A type of ion exchange chromatography using diethylaminoethyl cellulose (DEAE-CELLULOSE) as a positively charged resin. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

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.

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.

A species of gram-positive, rod-shaped bacteria isolated from the intestinal tract of humans and animals, the human mouth, and vagina. This organism produces the fermented product, acidophilus milk.

Methods of comparing two or more samples on the same two-dimensional gel electrophoresis gel.

The contents included in all or any segment of the GASTROINTESTINAL TRACT.

A technique that combines protein electrophoresis and double immunodiffusion. In this procedure proteins are first separated by gel electrophoresis (usually agarose), then made visible by immunodiffusion of specific antibodies. A distinct elliptical precipitin arc results for each protein detectable by the antisera.

A 513-kDa protein synthesized in the LIVER. It serves as the major structural protein of low-density lipoproteins (LIPOPROTEINS, LDL; LIPOPROTEINS, VLDL). It is the ligand for the LDL receptor (RECEPTORS, LDL) that promotes cellular binding and internalization of LDL particles.

Established cell cultures that have the potential to propagate indefinitely.

Bacteria which retain the crystal violet stain when treated by Gram's method.

Habitat of hot water naturally heated by underlying geologic processes. Surface hot springs have been used for BALNEOLOGY. Underwater hot springs are called HYDROTHERMAL VENTS.

Cholesterol which is contained in or bound to high-density lipoproteins (HDL), including CHOLESTEROL ESTERS and free cholesterol.

Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.