Amphibians: VERTEBRATES belonging to the class amphibia such as frogs, toads, newts and salamanders that live in a semiaquatic environment.Chytridiomycota: A phylum of fungi that was formerly considered a subdivision of Phycomycetes. They are the only fungi that produce motile spores (zoospores) at some stage in their life cycle. Most are saprobes but they also include examples of plant, animal, and fungal pathogens.Amphibian Proteins: Proteins obtained from species in the class of AMPHIBIANS.Ranidae: The family of true frogs of the order Anura. The family occurs worldwide except in Antarctica.Anura: An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.Bufonidae: The family of true toads belonging to the order Anura. The genera include Bufo, Ansonia, Nectophrynoides, and Atelopus.Urodela: An order of the Amphibia class which includes salamanders and newts. They are characterized by usually having slim bodies and tails, four limbs of about equal size (except in Sirenidae), and a reduction in skull bones.Salamandridae: A family of Urodela consisting of 15 living genera and about 42 species and occurring in North America, Europe, Asia, and North Africa.Ambystoma: A genus of the Ambystomatidae family. The best known species are the axolotl AMBYSTOMA MEXICANUM and the closely related tiger salamander Ambystoma tigrinum. They may retain gills and remain aquatic without developing all of the adult characteristics. However, under proper changes in the environment they metamorphose.Ranavirus: A genus of IRIDOVIRIDAE which infects fish, amphibians and reptiles. It is non-pathogenic for its natural host, Rana pipiens, but is lethal for other frogs, toads, turtles and salamanders. Frog virus 3 is the type species.Ambystoma mexicanum: A salamander found in Mexican mountain lakes and accounting for about 30 percent of the urodeles used in research. The axolotl remains in larval form throughout its life, a phenomenon known as neoteny.Reptiles: Cold-blooded, air-breathing VERTEBRATES belonging to the class Reptilia, usually covered with external scales or bony plates.Amphibian Venoms: Venoms produced by frogs, toads, salamanders, etc. The venom glands are usually on the skin of the back and contain cardiotoxic glycosides, cholinolytics, and a number of other bioactive materials, many of which have been characterized. The venoms have been used as arrow poisons and include bufogenin, bufotoxin, bufagin, bufotalin, histrionicotoxins, and pumiliotoxin.Triturus: A genus of aquatic newts in the Salamandridae family. During breeding season many Triturus males have a dorsal crest which also serves as an accessory respiratory organ. One of the common Triturus species is Triturus cristatus (crested newt).Xenopus laevis: The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.Metamorphosis, Biological: Profound physical changes during maturation of living organisms from the immature forms to the adult forms, such as from TADPOLES to frogs; caterpillars to BUTTERFLIES.Bufo arenarum: A species of the true toads, Bufonidae, found in South America.Rana pipiens: A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.Bufo marinus: A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.MycosesRana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Ponds: Inland bodies of standing FRESHWATER usually smaller than LAKES. They can be man-made or natural but there is no universal agreement as to their exact size. Some consider a pond to be a small body of water that is shallow enough for sunlight to reach the bottom.Animal DiseasesNotophthalmus viridescens: A species of newt in the Salamandridae family in which the larvae transform into terrestrial eft stage and later into an aquatic adult. They occur from Canada to southern United States. Viridescens refers to the greenish color often found in this species.Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.Endangered Species: An animal or plant species in danger of extinction. Causes can include human activity, changing climate, or change in predator/prey ratios.DNA Virus InfectionsRana esculenta: An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".Xenopus Proteins: Proteins obtained from various species of Xenopus. Included here are proteins from the African clawed frog (XENOPUS LAEVIS). Many of these proteins have been the subject of scientific investigations in the area of MORPHOGENESIS and development.Gastrula: The developmental stage that follows BLASTULA or BLASTOCYST. It is characterized by the morphogenetic cell movements including invagination, ingression, and involution. Gastrulation begins with the formation of the PRIMITIVE STREAK, and ends with the formation of three GERM LAYERS, the body plan of the mature organism.Rana temporaria: A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.Saprolegnia: A genus of OOMYCETES in the family Saprolegniaceae. It is a parasite and pathogen of freshwater FISHES.Rana ridibunda: A species of the family Ranidae which occurs primarily in Europe and is used widely in biomedical research.Vertebrates: Animals having a vertebral column, members of the phylum Chordata, subphylum Craniata comprising mammals, birds, reptiles, amphibians, and fishes.Extinction, Biological: The ceasing of existence of a species or taxonomic groups of organisms.Dermatomycoses: Superficial infections of the skin or its appendages by any of various fungi.Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.Extremities: The farthest or outermost projections of the body, such as the HAND and FOOT.Fishes: A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.Regeneration: The physiological renewal, repair, or replacement of tissue.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.Atrazine: A selective triazine herbicide. Inhalation hazard is low and there are no apparent skin manifestations or other toxicity in humans. Acutely poisoned sheep and cattle may show muscular spasms, fasciculations, stiff gait, increased respiratory rates, adrenal degeneration, and congestion of the lungs, liver, and kidneys. (From The Merck Index, 11th ed)Biodiversity: The variety of all native living organisms and their various forms and interrelationships.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.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Mammals: Warm-blooded vertebrate animals belonging to the class Mammalia, including all that possess hair and suckle their young.Conservation of Natural Resources: The protection, preservation, restoration, and rational use of all resources in the total environment.Population Dynamics: The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).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.TailEmbryonic Induction: The complex processes of initiating CELL DIFFERENTIATION in the embryo. The precise regulation by cell interactions leads to diversity of cell types and specific pattern of organization (EMBRYOGENESIS).Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Vasotocin: A nonapeptide that contains the ring of OXYTOCIN and the side chain of ARG-VASOPRESSIN with the latter determining the specific recognition of hormone receptors. Vasotocin is the non-mammalian vasopressin-like hormone or antidiuretic hormone regulating water and salt metabolism.UreohydrolasesEctoderm: The outer of the three germ layers of an embryo.Ecosystem: 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)Salamandra: A genus of European newts in the Salamandridae family. The two species of this genus are Salamandra salamandra (European "fire" salamander) and Salamandra atra (European alpine salamander).Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.PanamaBase Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Gene Expression Regulation, Developmental: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.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.