Lymnaea: A genus of dextrally coiled freshwater snails that includes some species of importance as intermediate hosts of parasitic flukes.FMRFamide: A molluscan neuroactive peptide which induces a fast excitatory depolarizing response due to direct activation of amiloride-sensitive SODIUM CHANNELS. (From Nature 1995; 378(6558): 730-3)Snails: Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.Memory, Long-Term: Remembrance of information from 3 or more years previously.Ganglia, Invertebrate: Clusters of neuronal cell bodies in invertebrates. Invertebrate ganglia may also contain neuronal processes and non-neuronal supporting cells. Many invertebrate ganglia are favorable subjects for research because they have small numbers of functional neuronal types which can be identified from one animal to another.Molluscacides: Agents destructive to snails and other mollusks.Invertebrate Hormones: Hormones produced by invertebrates, usually insects, mollusks, annelids, and helminths.Respiratory Physiological Processes: Biological actions and events that support the functions of the RESPIRATORY SYSTEM.Fasciola hepatica: A species of helminth commonly called the sheep liver fluke. It occurs in the biliary passages, liver, and gallbladder during various stages of development. Snails and aquatic vegetation are the intermediate hosts. Occasionally seen in man, it is most common in sheep and cattle.Paramphistomatidae: A family of flukes of the class Trematoda found in the intestinal tract and liver of animals and man. Some of the genera are Homalagaster, Gastrodiscus, Paramphistomum, Watsonius, Nilocotyle, Gigantocotyle, Gastrothylax, Macropotrema, Ceylonocotyle, Zygocotyle, Cotylophoron, and Calicophoron.Fascioliasis: Liver disease caused by infections with parasitic flukes of the genus FASCIOLA, such as FASCIOLA HEPATICA.Fasciola: A genus of trematode liver flukes of the family Fasciolidae. Two species of this genus are F. hepatica and F. gigantica. The parasites are found in the liver and gallbladder and associated ducts in mammals and occasionally man. F. gigantica occurs rarely in man.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.Access to Information: Individual's rights to obtain and use information collected or generated by others.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Journal Impact Factor: A quantitative measure of the frequency on average with which articles in a journal have been cited in a given period of time.Mimusops: A plant genus of the family SAPOTACEAE. Members contain triterpenoid saponins. Latex from bark incisions is processed into gutta balata.Publishing: "The business or profession of the commercial production and issuance of literature" (Webster's 3d). It includes the publisher, publication processes, editing and editors. Production may be by conventional printing methods or by electronic publishing.Electronic Mail: Messages between computer users via COMPUTER COMMUNICATION NETWORKS. This feature duplicates most of the features of paper mail, such as forwarding, multiple copies, and attachments of images and other file types, but with a speed advantage. The term also refers to an individual message sent in this way.HemocyaninAccounts Payable and Receivable: Short-term debt obligations and assets occurring in the regular course of operational transactions.Conditioning, Operant: Learning situations in which the sequence responses of the subject are instrumental in producing reinforcement. When the correct response occurs, which involves the selection from among a repertoire of responses, the subject is immediately reinforced.Memory: Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.Conditioning, Classical: Learning that takes place when a conditioned stimulus is paired with an unconditioned stimulus.Conditioning (Psychology): A general term referring to the learning of some particular response.Silicon Dioxide: Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, QUARTZ, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid.Moles: Any of numerous burrowing mammals found in temperate regions and having minute eyes often covered with skin.Nerve Endings: Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.Microscopy, Electron: 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.Drug Residues: Drugs and their metabolites which are found in the edible tissues and milk of animals after their medication with specific drugs. This term can also apply to drugs found in adipose tissue of humans after drug treatment.Cadmium: An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.Amphipoda: An order of mostly marine CRUSTACEA containing more than 5500 species in over 100 families. Like ISOPODA, the other large order in the superorder Peracarida, members are shrimp-like in appearance, have sessile compound eyes, and no carapace. But unlike Isopoda, they possess thoracic gills and their bodies are laterally compressed.Cadmium Poisoning: Poisoning occurring after exposure to cadmium compounds or fumes. It may cause gastrointestinal syndromes, anemia, or pneumonitis.Toxicity Tests, Acute: Experiments designed to determine the potential toxic effects of one-time, short-term exposure to a chemical or chemicals.Fasciolidae: A family of flukes of the class Trematoda occurring primarily in the liver of animals and man. There are six genera: Fasciola, Fasciolopsis, Fascioloides, Tenuifasciola, Parafasciolopsis, and Protofasciola. The adult form of Fasciolopsis occurs in the intestines of pigs and man.Fascioloidiasis: Infection of cattle and other herbivores with the giant liver fluke Fascioloides magna. It is characterized by extensive destruction of the liver parenchyma.Guadeloupe: The name of two islands of the West Indies, separated by a narrow channel. Their capital is Basse-Terre. They were discovered by Columbus in 1493, occupied by the French in 1635, held by the British at various times between 1759 and 1813, transferred to Sweden in 1813, and restored to France in 1816. Its status was changed from colony to a French overseas department in 1946. Columbus named it in honor of the monastery of Santa Maria de Guadalupe in Spain. (From Webster's New Geographical Dictionary, 1988, p470 & Room, Brewer's Dictionary of Names, 1992, p221)Trematoda: Class of parasitic flukes consisting of three subclasses, Monogenea, Aspidogastrea, and Digenea. The digenetic trematodes are the only ones found in man. They are endoparasites and require two hosts to complete their life cycle.Cisterna Magna: One of three principal openings in the SUBARACHNOID SPACE. They are also known as cerebellomedullary cistern, and collectively as cisterns.Databases, Chemical: Databases devoted to knowledge about specific chemicals.QuinuclidinesTetrahydroisoquinolines: A group of ISOQUINOLINES in which the nitrogen containing ring is protonated. They derive from the non-enzymatic Pictet-Spengler condensation of CATECHOLAMINES with ALDEHYDES.Databases, Pharmaceutical: Databases devoted to knowledge about PHARMACEUTICAL PRODUCTS.Muscarinic Antagonists: Drugs that bind to but do not activate MUSCARINIC RECEPTORS, thereby blocking the actions of endogenous ACETYLCHOLINE or exogenous agonists. Muscarinic antagonists have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system.Drug Discovery: The process of finding chemicals for potential therapeutic use.Succinates: Derivatives of SUCCINIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a 1,4-carboxy terminated aliphatic structure.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.New Zealand: A group of islands in the southwest Pacific. Its capital is Wellington. It was discovered by the Dutch explorer Abel Tasman in 1642 and circumnavigated by Cook in 1769. Colonized in 1840 by the New Zealand Company, it became a British crown colony in 1840 until 1907 when colonial status was terminated. New Zealand is a partly anglicized form of the original Dutch name Nieuw Zeeland, new sea land, possibly with reference to the Dutch province of Zeeland. (From Webster's New Geographical Dictionary, 1988, p842 & Room, Brewer's Dictionary of Names, 1992, p378)Helix (Snails): A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.Trout: Various fish of the family SALMONIDAE, usually smaller than salmon. They are mostly restricted to cool clear freshwater. Some are anadromous. They are highly regarded for their handsome colors, rich well-flavored flesh, and gameness as an angling fish. The genera Salvelinus, Salmo, and ONCORHYNCHUS have been introduced virtually throughout the world.Medicago truncatula: A plant species of the family FABACEAE used to study GENETICS because it is DIPLOID, self fertile, has a small genome, and short generation time.Solanum nigrum: A plant species of the genus SOLANUM, family SOLANACEAE that contains steroidal glycosides.Cercaria: The free-swimming larval forms of parasites found in an intermediate host.Population Density: Number of individuals in a population relative to space.