Cholera Toxin: An ENTEROTOXIN from VIBRIO CHOLERAE. It consists of two major protomers, the heavy (H) or A subunit and the B protomer which consists of 5 light (L) or B subunits. The catalytic A subunit is proteolytically cleaved into fragments A1 and A2. The A1 fragment is a MONO(ADP-RIBOSE) TRANSFERASE. The B protomer binds cholera toxin to intestinal epithelial cells, and facilitates the uptake of the A1 fragment. The A1 catalyzed transfer of ADP-RIBOSE to the alpha subunits of heterotrimeric G PROTEINS activates the production of CYCLIC AMP. Increased levels of cyclic AMP are thought to modulate release of fluid and electrolytes from intestinal crypt cells.T-2 Toxin: A potent mycotoxin produced in feedstuffs by several species of the genus FUSARIUM. It elicits a severe inflammatory reaction in animals and has teratogenic effects.Tetanus Toxin: Protein synthesized by CLOSTRIDIUM TETANI as a single chain of ~150 kDa with 35% sequence identity to BOTULINUM TOXIN that is cleaved to a light and a heavy chain that are linked by a single disulfide bond. Tetanolysin is the hemolytic and tetanospasmin is the neurotoxic principle. The toxin causes disruption of the inhibitory mechanisms of the CNS, thus permitting uncontrolled nervous activity, leading to fatal CONVULSIONS.Botulinum Toxins, Type A: A serotype of botulinum toxins that has specificity for cleavage of SYNAPTOSOMAL-ASSOCIATED PROTEIN 25.Marine Toxins: Toxic or poisonous substances elaborated by marine flora or fauna. They include also specific, characterized poisons or toxins for which there is no more specific heading, like those from poisonous FISHES.Shiga Toxins: A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; (RNA, RIBOSOMAL) with PEPTIDE ELONGATION FACTORS. They include SHIGA TOXIN which is produced by SHIGELLA DYSENTERIAE and a variety of shiga-like toxins that are produced by pathologic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157.Shiga Toxin 2: A toxin produced by certain pathogenic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157. It shares 50-60% homology with SHIGA TOXIN and SHIGA TOXIN 1.Shiga Toxin 1: A toxin produced by certain pathogenic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157. It is closely related to SHIGA TOXIN produced by SHIGELLA DYSENTERIAE.Adenylate Cyclase Toxin: One of the virulence factors produced by virulent BORDETELLA organisms. It is a bifunctional protein with both ADENYLYL CYCLASES and hemolysin components.Enterotoxins: Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc.; most common enterotoxins are produced by bacteria.Antitoxins: Antisera from immunized animals that is purified and used as a passive immunizing agent against specific BACTERIAL TOXINS.Hemolysin Proteins: Proteins from BACTERIA and FUNGI that are soluble enough to be secreted to target ERYTHROCYTES and insert into the membrane to form beta-barrel pores. Biosynthesis may be regulated by HEMOLYSIN FACTORS.Scorpion Venoms: Venoms from animals of the order Scorpionida of the class Arachnida. They contain neuro- and hemotoxins, enzymes, and various other factors that may release acetylcholine and catecholamines from nerve endings. Of the several protein toxins that have been characterized, most are immunogenic.Clostridium difficile: A common inhabitant of the colon flora in human infants and sometimes in adults. It produces a toxin that causes pseudomembranous enterocolitis (ENTEROCOLITIS, PSEUDOMEMBRANOUS) in patients receiving antibiotic therapy.Mycotoxins: Toxic compounds produced by FUNGI.Cytotoxins: Substances that are toxic to cells; they may be involved in immunity or may be contained in venoms. These are distinguished from CYTOSTATIC AGENTS in degree of effect. Some of them are used as CYTOTOXIC ANTIBIOTICS. The mechanism of action of many of these are as ALKYLATING AGENTS or MITOSIS MODULATORS.Neuromuscular Agents: Drugs used for their actions on skeletal muscle. Included are agents that act directly on skeletal muscle, those that alter neuromuscular transmission (NEUROMUSCULAR BLOCKING AGENTS), and drugs that act centrally as skeletal muscle relaxants (MUSCLE RELAXANTS, CENTRAL). Drugs used in the treatment of movement disorders are ANTI-DYSKINESIA AGENTS.Bacterial Proteins: Proteins found in any species of bacterium.Scorpions: Arthropods of the order Scorpiones, of which 1500 to 2000 species have been described. The most common live in tropical or subtropical areas. They are nocturnal and feed principally on insects and other arthropods. They are large arachnids but do not attack man spontaneously. They have a venomous sting. Their medical significance varies considerably and is dependent on their habits and venom potency rather than on their size. At most, the sting is equivalent to that of a hornet but certain species possess a highly toxic venom potentially fatal to humans. (From Dorland, 27th ed; Smith, Insects and Other Arthropods of Medical Importance, 1973, p417; Barnes, Invertebrate Zoology, 5th ed, p503)Ricin: A protein phytotoxin from the seeds of Ricinus communis, the castor oil plant. It agglutinates cells, is proteolytic, and causes lethal inflammation and hemorrhage if taken internally.Neurotoxins: Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system. Most venoms contain neurotoxic substances. Myotoxins are included in this concept.Clostridium botulinum: A species of anaerobic, gram-positive, rod-shaped bacteria in the family Clostridiaceae that produces proteins with characteristic neurotoxicity. It is the etiologic agent of BOTULISM in humans, wild fowl, HORSES; and CATTLE. Seven subtypes (sometimes called antigenic types, or strains) exist, each producing a different botulinum toxin (BOTULINUM TOXINS). The organism and its spores are widely distributed in nature.Bacillus thuringiensis: A species of gram-positive bacteria which may be pathogenic for certain insects. It is used for the biological control of the Gypsy moth.Spider Venoms: Venoms of arthropods of the order Araneida of the ARACHNIDA. The venoms usually contain several protein fractions, including ENZYMES, hemolytic, neurolytic, and other TOXINS, BIOLOGICAL.ADP Ribose Transferases: Enzymes that transfer the ADP-RIBOSE group of NAD or NADP to proteins or other small molecules. Transfer of ADP-ribose to water (i.e., hydrolysis) is catalyzed by the NADASES. The mono(ADP-ribose)transferases transfer a single ADP-ribose. POLY(ADP-RIBOSE) POLYMERASES transfer multiple units of ADP-ribose to protein targets, building POLY ADENOSINE DIPHOSPHATE RIBOSE in linear or branched chains.Cnidarian Venoms: Venoms from jellyfish; CORALS; SEA ANEMONES; etc. They contain hemo-, cardio-, dermo- , and neuro-toxic substances and probably ENZYMES. They include palytoxin, sarcophine, and anthopleurine.Toxoids: Preparations of pathogenic organisms or their derivatives made nontoxic and intended for active immunologic prophylaxis. They include deactivated toxins. Anatoxin toxoids are distinct from anatoxins that are TROPANES found in CYANOBACTERIA.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.Adenosine Diphosphate Ribose: An ester formed between the aldehydic carbon of RIBOSE and the terminal phosphate of ADENOSINE DIPHOSPHATE. It is produced by the hydrolysis of nicotinamide-adenine dinucleotide (NAD) by a variety of enzymes, some of which transfer an ADP-ribosyl group to target proteins.Bacillus anthracis: A species of bacteria that causes ANTHRAX in humans and animals.Vibrio cholerae: The etiologic agent of CHOLERA.Exfoliatins: Protein exotoxins from Staphylococcus aureus, phage type II, which cause epidermal necrolysis. They are proteins with a molecular weight of 26,000 to 32,000. They cause a condition variously called scaled skin, Lyell or Ritter syndrome, epidermal exfoliative disease, toxic epidermal necrolysis, etc.Clostridium perfringens: The most common etiologic agent of GAS GANGRENE. It is differentiable into several distinct types based on the distribution of twelve different toxins.Killer Factors, Yeast: Protein factors released from one species of YEAST that are selectively toxic to another species of yeast.Exotoxins: Toxins produced, especially by bacterial or fungal cells, and released into the culture medium or environment.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.Endotoxins: Toxins closely associated with the living cytoplasm or cell wall of certain microorganisms, which do not readily diffuse into the culture medium, but are released upon lysis of the cells.Bordetella pertussis: A species of gram-negative, aerobic bacteria that is the causative agent of WHOOPING COUGH. Its cells are minute coccobacilli that are surrounded by a slime sheath.Sea Anemones: The order Actiniaria, in the class ANTHOZOA, comprised of large, solitary polyps. All species are carnivorous.Anthrax: An acute infection caused by the spore-forming bacteria BACILLUS ANTHRACIS. It commonly affects hoofed animals such as sheep and goats. Infection in humans often involves the skin (cutaneous anthrax), the lungs (inhalation anthrax), or the gastrointestinal tract. Anthrax is not contagious and can be treated with antibiotics.Shellfish Poisoning: Poisoning from toxins present in bivalve mollusks that have been ingested. Four distinct types of shellfish poisoning are recognized based on the toxin involved.Enterocolitis, Pseudomembranous: An acute inflammation of the INTESTINAL MUCOSA that is characterized by the presence of pseudomembranes or plaques in the SMALL INTESTINE (pseudomembranous enteritis) and the LARGE INTESTINE (pseudomembranous colitis). It is commonly associated with antibiotic therapy and CLOSTRIDIUM DIFFICILE colonization.Clostridium Infections: Infections with bacteria of the genus CLOSTRIDIUM.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Virulence Factors: Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: TOXINS, BIOLOGICAL and surface adhesion molecules that effect the ability of the microorganism to invade and colonize a host. (From Davis et al., Microbiology, 4th ed. p486)GTP-Binding Proteins: Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-.Lethal Dose 50: The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.Trihexosylceramides: Glycosphingolipids which contain as their polar head group a trisaccharide (galactose-galactose-glucose) moiety bound in glycosidic linkage to the hydroxyl group of ceramide. Their accumulation in tissue, due to a defect in ceramide trihexosidase, is the cause of angiokeratoma corporis diffusum (FABRY DISEASE).Pest Control, Biological: Use of naturally-occuring or genetically-engineered organisms to reduce or eliminate populations of pests.Corynebacterium diphtheriae: A species of gram-positive, asporogenous bacteria in which three cultural types are recognized. These types (gravis, intermedius, and mitis) were originally given in accordance with the clinical severity of the cases from which the different strains were most frequently isolated. This species is the causative agent of DIPHTHERIA.Immunotoxins: Semisynthetic conjugates of various toxic molecules, including RADIOACTIVE ISOTOPES and bacterial or plant toxins, with specific immune substances such as IMMUNOGLOBULINS; MONOCLONAL ANTIBODIES; and ANTIGENS. The antitumor or antiviral immune substance carries the toxin to the tumor or infected cell where the toxin exerts its poisonous effect.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.Shigella dysenteriae: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria that is extremely pathogenic and causes severe dysentery. Infection with this organism often leads to ulceration of the intestinal epithelium.G(M1) Ganglioside: A specific monosialoganglioside that accumulates abnormally within the nervous system due to a deficiency of GM1-b-galactosidase, resulting in GM1 gangliosidosis.Trichothecenes: Usually 12,13-epoxytrichothecenes, produced by Fusaria, Stachybotrys, Trichoderma and other fungi, and some higher plants. They may contaminate food or feed grains, induce emesis and hemorrhage in lungs and brain, and damage bone marrow due to protein and DNA synthesis inhibition.Clostridium: 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.Elapid Venoms: Venoms from snakes of the family Elapidae, including cobras, kraits, mambas, coral, tiger, and Australian snakes. The venoms contain polypeptide toxins of various kinds, cytolytic, hemolytic, and neurotoxic factors, but fewer enzymes than viper or crotalid venoms. Many of the toxins have been characterized.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Elapidae: A family of extremely venomous snakes, comprising coral snakes, cobras, mambas, kraits, and sea snakes. They are widely distributed, being found in the southern United States, South America, Africa, southern Asia, Australia, and the Pacific Islands. The elapids include three subfamilies: Elapinae, Hydrophiinae, and Lauticaudinae. Like the viperids, they have venom fangs in the front part of the upper jaw. The mambas of Africa are the most dangerous of all snakes by virtue of their size, speed, and highly toxic venom. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, p329-33)Biological 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.Rabbits: 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.Saxitoxin: A compound that contains a reduced purine ring system but is not biosynthetically related to the purine alkaloids. It is a poison found in certain edible mollusks at certain times; elaborated by GONYAULAX and consumed by mollusks, fishes, etc. without ill effects. It is neurotoxic and causes RESPIRATORY PARALYSIS and other effects in MAMMALS, known as paralytic SHELLFISH poisoning.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Kinetics: The rate dynamics in chemical or physical systems.Adenylate Cyclase: An enzyme of the lyase class that catalyzes the formation of CYCLIC AMP and pyrophosphate from ATP. EC 18.104.22.168.Snake Venoms: Solutions or mixtures of toxic and nontoxic substances elaborated by snake (Ophidia) salivary glands for the purpose of killing prey or disabling predators and delivered by grooved or hollow fangs. They usually contain enzymes, toxins, and other factors.Oxocins: Compounds based on an 8-membered heterocyclic ring including an oxygen. They can be considered medium ring ethers.Receptors, Peptide: Cell surface receptors that bind peptide messengers with high affinity and regulate intracellular signals which influence the behavior of cells.Botulinum Antitoxin: Antiserum given therapeutically in BOTULISM.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Diphtheria Antitoxin: An antitoxin produced against the toxin of CORYNEBACTERIUM DIPHTHERIAE that is used for the treatment of DIPHTHERIA.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Vero Cells: A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.Streptolysins: Exotoxins produced by certain strains of streptococci, particularly those of group A (STREPTOCOCCUS PYOGENES), that cause HEMOLYSIS.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Clostridium tetani: The cause of TETANUS in humans and domestic animals. It is a common inhabitant of human and horse intestines as well as soil. Two components make up its potent exotoxin activity, a neurotoxin and a hemolytic toxin.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.Cholera: An acute diarrheal disease endemic in India and Southeast Asia whose causative agent is VIBRIO CHOLERAE. This condition can lead to severe dehydration in a matter of hours unless quickly treated.Receptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Genes, Bacterial: The functional hereditary units of BACTERIA.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.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.Ribosome Inactivating Proteins, Type 2: Ribosome inactivating proteins consisting of two polypeptide chains, the toxic A subunit and a lectin B subunit, linked by disulfide bridges. The lectin portion binds to cell surfaces and facilitates transport into the ENDOPLASMIC RETICULUM.Superantigens: Microbial antigens that have in common an extremely potent activating effect on T-cells that bear a specific variable region. Superantigens cross-link the variable region with class II MHC proteins regardless of the peptide binding in the T-cell receptor's pocket. The result is a transient expansion and subsequent death and anergy of the T-cells with the appropriate variable regions.Abrin: A toxic lectin from the seeds of jequirity, Abrus precatorius L. Very active poison. Five different proteins have so far been isolated: Abrus agglutinin, the component responsible for: hemagglutinating activity, & abrins a-d, the toxic principals each consisting of two peptide chains are held together by disulfide bonds.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Microcystins: Cyclic heptapeptides found in MICROCYSTIS and other CYANOBACTERIA. Hepatotoxic and carcinogenic effects have been noted. They are sometimes called cyanotoxins, which should not be confused with chemicals containing a cyano group (CN) which are toxic.Escherichia coli Infections: Infections with bacteria of the species ESCHERICHIA COLI.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Virulence: The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.Manduca: A genus of sphinx or hawk moths of the family Sphingidae. These insects are used in molecular biology studies during all stages of their life cycle.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Staphylococcus aureus: Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Spiders: Arthropods of the class ARACHNIDA, order Araneae. Except for mites and ticks, spiders constitute the largest order of arachnids, with approximately 37,000 species having been described. The majority of spiders are harmless, although some species can be regarded as moderately harmful since their bites can lead to quite severe local symptoms. (From Barnes, Invertebrate Zoology, 5th ed, p508; Smith, Insects and Other Arthropods of Medical Importance, 1973, pp424-430)Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Diarrhea: An increased liquidity or decreased consistency of FECES, such as running stool. Fecal consistency is related to the ratio of water-holding capacity of insoluble solids to total water, rather than the amount of water present. Diarrhea is not hyperdefecation or increased fecal weight.Fusarium: A mitosporic Hypocreales fungal genus, various species of which are important parasitic pathogens of plants and a variety of vertebrates. Teleomorphs include GIBBERELLA.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Gangliosides: A subclass of ACIDIC GLYCOSPHINGOLIPIDS. They contain one or more sialic acid (N-ACETYLNEURAMINIC ACID) residues. Using the Svennerholm system of abbrevations, gangliosides are designated G for ganglioside, plus subscript M, D, or T for mono-, di-, or trisialo, respectively, the subscript letter being followed by a subscript arabic numeral to indicated sequence of migration in thin-layer chromatograms. (From Oxford Dictionary of Biochemistry and Molecular Biology, 1997)Synaptosomes: Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates.SesquiterpenesDinoflagellida: Flagellate EUKARYOTES, found mainly in the oceans. They are characterized by the presence of transverse and longitudinal flagella which propel the organisms in a rotating manner through the water. Dinoflagellida were formerly members of the class Phytomastigophorea under the old five kingdom paradigm.Escherichia coli O157: A verocytotoxin-producing serogroup belonging to the O subfamily of Escherichia coli which has been shown to cause severe food-borne disease. A strain from this serogroup, serotype H7, which produces SHIGA TOXINS, has been linked to human disease outbreaks resulting from contamination of foods by E. coli O157 from bovine origin.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.Staphylococcal Scalded Skin Syndrome: A disease of infants due to group 2 phage type 17 staphylococci that produce an epidermolytic exotoxin. Superficial fine vesicles and bullae form and rupture easily, resulting in loss of large sheets of epidermis.Lepidoptera: A large order of insects comprising the butterflies and moths.Cercopithecus aethiops: A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.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.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.Spasm: An involuntary contraction of a muscle or group of muscles. Spasms may involve SKELETAL MUSCLE or SMOOTH MUSCLE.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Cobra Neurotoxin Proteins: Toxins, contained in cobra (Naja) venom that block cholinergic receptors; two specific proteins have been described, the small (short, Type I) and the large (long, Type II) which also exist in other Elapid venoms.Enzyme-Linked Immunosorbent Assay: An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.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.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Conotoxins: Peptide neurotoxins from the marine fish-hunting snails of the genus CONUS. They contain 13 to 29 amino acids which are strongly basic and are highly cross-linked by disulfide bonds. There are three types of conotoxins, omega-, alpha-, and mu-. OMEGA-CONOTOXINS inhibit voltage-activated entry of calcium into the presynaptic membrane and therefore the release of ACETYLCHOLINE. Alpha-conotoxins inhibit the postsynaptic acetylcholine receptor. Mu-conotoxins prevent the generation of muscle action potentials. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)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.Molecular Weight: The sum of the weight of all the atoms in a molecule.Blepharospasm: Excessive winking; tonic or clonic spasm of the orbicularis oculi muscle.Sodium Channels: Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Mollusk Venoms: Venoms from mollusks, including CONUS and OCTOPUS species. The venoms contain proteins, enzymes, choline derivatives, slow-reacting substances, and several characterized polypeptide toxins that affect the nervous system. Mollusk venoms include cephalotoxin, venerupin, maculotoxin, surugatoxin, conotoxins, and murexine.Indican: A substance occurring in the urine of mammals and also in blood plasma as the normal metabolite of tryptophan. An increased urinary excretion of indican is seen in Hartnup disease from the bacterial degradation of unabsorbed tryptophan.Mice, Inbred BALB CSequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Dermotoxins: Specific substances elaborated by plants, microorganisms or animals that cause damage to the skin; they may be proteins or other specific factors or substances; constituents of spider, jellyfish or other venoms cause dermonecrosis and certain bacteria synthesize dermolytic agents.Immunodiffusion: Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.Ribosome Inactivating Proteins, Type 1: Ribosome inactivating proteins consisting of only the toxic A subunit, which is a polypeptide of around 30 kDa.Insecticides: Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Injections, Intramuscular: Forceful administration into a muscle of liquid medication, nutrient, or other fluid through a hollow needle piercing the muscle and any tissue covering it.Anthrax Vaccines: Vaccines or candidate vaccines used to prevent ANTHRAX.Pasteurella multocida: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria normally found in the flora of the mouth and respiratory tract of animals and birds. It causes shipping fever (see PASTEURELLOSIS, PNEUMONIC); HEMORRHAGIC BACTEREMIA; and intestinal disease in animals. In humans, disease usually arises from a wound infection following a bite or scratch from domesticated animals.Erabutoxins: Toxins isolated from the venom of Laticauda semifasciata, a sea snake (Hydrophid); immunogenic, basic polypeptides of 62 amino acids, folded by four disulfide bonds, block neuromuscular end-plates irreversibly, thus causing paralysis and severe muscle damage; they are similar to Elapid neurotoxins.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Shellfish: Aquatic invertebrates belonging to the phylum MOLLUSCA or the subphylum CRUSTACEA, and used as food.Reptilian Proteins: Proteins obtained from species of REPTILES.Torticollis: A symptom, not a disease, of a twisted neck. In most instances, the head is tipped toward one side and the chin rotated toward the other. The involuntary muscle contractions in the neck region of patients with torticollis can be due to congenital defects, trauma, inflammation, tumors, and neurological or other factors.Hemolytic-Uremic Syndrome: A syndrome that is associated with microvascular diseases of the KIDNEY, such as RENAL CORTICAL NECROSIS. It is characterized by hemolytic anemia (ANEMIA, HEMOLYTIC); THROMBOCYTOPENIA; and ACUTE RENAL FAILURE.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Neutralization Tests: The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Cell Survival: The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Endocytosis: Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.Binding, Competitive: The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.Immunization: Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Muscle Spasticity: A form of muscle hypertonia associated with upper MOTOR NEURON DISEASE. Resistance to passive stretch of a spastic muscle results in minimal initial resistance (a "free interval") followed by an incremental increase in muscle tone. Tone increases in proportion to the velocity of stretch. Spasticity is usually accompanied by HYPERREFLEXIA and variable degrees of MUSCLE WEAKNESS. (From Adams et al., Principles of Neurology, 6th ed, p54)HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.Guanosine 5'-O-(3-Thiotriphosphate): Guanosine 5'-(trihydrogen diphosphate), monoanhydride with phosphorothioic acid. A stable GTP analog which enjoys a variety of physiological actions such as stimulation of guanine nucleotide-binding proteins, phosphoinositide hydrolysis, cyclic AMP accumulation, and activation of specific proto-oncogenes.Moths: Insects of the suborder Heterocera of the order LEPIDOPTERA.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Food Contamination: The presence in food of harmful, unpalatable, or otherwise objectionable foreign substances, e.g. chemicals, microorganisms or diluents, before, during, or after processing or storage.Peptide Elongation Factor 2: Peptide Elongation Factor 2 catalyzes the translocation of peptidyl-tRNA from the A site to the P site of eukaryotic ribosomes by a process linked to the hydrolysis of GTP to GDP.Intestinal Mucosa: Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.Bungarotoxins: Neurotoxic proteins from the venom of the banded or Formosan krait (Bungarus multicinctus, an elapid snake). alpha-Bungarotoxin blocks nicotinic acetylcholine receptors and has been used to isolate and study them; beta- and gamma-bungarotoxins act presynaptically causing acetylcholine release and depletion. Both alpha and beta forms have been characterized, the alpha being similar to the large, long or Type II neurotoxins from other elapid venoms.Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Pertussis Vaccine: A suspension of killed Bordetella pertussis organisms, used for immunization against pertussis (WHOOPING COUGH). It is generally used in a mixture with diphtheria and tetanus toxoids (DTP). There is an acellular pertussis vaccine prepared from the purified antigenic components of Bordetella pertussis, which causes fewer adverse reactions than whole-cell vaccine and, like the whole-cell vaccine, is generally used in a mixture with diphtheria and tetanus toxoids. (From Dorland, 28th ed)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.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Bordetella: A genus of gram-negative, aerobic bacteria whose cells are minute coccobacilli. It consists of both parasitic and pathogenic species.Bacterial Vaccines: Suspensions of attenuated or killed bacteria administered for the prevention or treatment of infectious bacterial disease.Type C Phospholipases: A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of GLYCEROPHOSPHOLIPIDS. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of PHOSPHATIDYLCHOLINE (EC 22.214.171.124), it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of PHOSPHATIDYLINOSITOLS.Agatoxins: A class of polyamine and peptide toxins which are isolated from the venom of spiders such as Agelenopsis aperta.Enteritis: Inflammation of any segment of the SMALL INTESTINE.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.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Enterotoxemia: Disease caused by the liberation of exotoxins of CLOSTRIDIUM PERFRINGENS in the intestines of sheep, goats, cattle, foals, and piglets. Type B enterotoxemia in lambs is lamb dysentery; type C enterotoxemia in mature sheep produces "struck", and in calves, lambs and piglets it produces hemorrhagic enterotoxemia; type D enterotoxemia in sheep and goats is pulpy-kidney disease or overeating disease.Receptors, Cholinergic: Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.Guanosine Triphosphate: Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.Pore Forming Cytotoxic Proteins: Proteins secreted from an organism which form membrane-spanning pores in target cells to destroy them. This is in contrast to PORINS and MEMBRANE TRANSPORT PROTEINS that function within the synthesizing organism and COMPLEMENT immune proteins. These pore forming cytotoxic proteins are a form of primitive cellular defense which are also found in human LYMPHOCYTES.Food Microbiology: 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.Adenosine Diphosphate Sugars: Esters formed between the aldehydic carbon of sugars and the terminal phosphate of adenosine diphosphate.Cricetulus: A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.Cholera Vaccines: Vaccines or candidate vaccines used to prevent infection with VIBRIO CHOLERAE. The original cholera vaccine consisted of killed bacteria, but other kinds of vaccines now exist.Insecticide Resistance: The development by insects of resistance to insecticides.Cobra Venoms: Venoms from snakes of the genus Naja (family Elapidae). They contain many specific proteins that have cytotoxic, hemolytic, neurotoxic, and other properties. Like other elapid venoms, they are rich in enzymes. They include cobramines and cobralysins.Ciguatoxins: Polycyclic ethers produced by Gambierdiscus (DINOFLAGELLATES) from gambiertoxins, which are ingested by fish which in turn may be ingested by humans who are susceptible to the CIGUATERA POISONING.Disulfides: Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Protein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.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.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.Nucleoside Diphosphate SugarsEnterohemorrhagic Escherichia coli: Strains of ESCHERICHIA COLI that are a subgroup of SHIGA-TOXIGENIC ESCHERICHIA COLI. They cause non-bloody and bloody DIARRHEA; HEMOLYTIC UREMIC SYNDROME; and hemorrhagic COLITIS. An important member of this subgroup is ESCHERICHIA COLI O157-H7.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.Temperature: 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.Snakes: Limbless REPTILES of the suborder Serpentes.Administration, Intranasal: Delivery of medications through the nasal mucosa.Enterotoxigenic Escherichia coli: Strains of ESCHERICHIA COLI that produce or contain at least one member of either heat-labile or heat-stable ENTEROTOXINS. The organisms colonize the mucosal surface of the small intestine and elaborate their enterotoxins causing DIARRHEA. They are mainly associated with tropical and developing countries and affect susceptible travelers to those places.