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At least 415 records · Page 23Linked to original sources
PubMed1986

Light and electron microscopic study on complex carbohydrates in the testis of Salamandra salamandra L. (Amphibia, Urodela).

The distribution of complex carbohydrates was studied in the testis of the European fire salamander, Salamandra salamandra, by light- and electron-microscopic methods. The basal laminae and fibrous structures in the connective tissue between the lobules are PAS-positive. After alcianblue staining (at pH = 2.8), acid mucopolysaccharides could be demonstrated in steroid hormone-producing cells in the interstitial tissue between lobules containing spermatids, spermatozoa, and lobules after spermiation, as well as in most of the Sertoli cells in lobules after spermiation. In all spermatogenic stages from secondary spermatocytes to mature sperms, dictyosome-like structures and flat vesicles showed a distinct contrast enhancement, as did parts of the acrosome after treatment with the phosphotungstic acid-chromic acid method for electron microscopy.

Acrosome↗
PubMed2001

Water wave communication in the genus Bombina (amphibia).

Amphibians were phylogenetically the first vertebrates to leave the aquatic environment and cope with terrestrial conditions including effects of gravity and substrate on movement and communication. Studies of extant primitive amphibians, which have conserved ancestral morphology and behavior, may help us to understand how gravitational adaptation from aquatic to terrestrial environments occurred. The anuran genus Bombina is a candidate for this type of investigation. In particular, a member of this genus, B. orientalis, is known for its low reaction threshold to minor changes of angular acceleration. We hypothesize that a heightened sensitivity to angular and mechanical accelerations evolved with wave communication. Comparisons of such behavior among B. variegata, B. bombina and B. orientalis may shed light on the evolution of reproductive systems based on water wave communication and relevant vestibular sensitivity. This may represent a transition to derived vocalization modes, which is seen in B. bombina to a certain degree.

Animal Communication↗
PubMed1997

Regulation of body water balance in reedfrogs (superspecies Hyperolius viridiflavus and Hyperolius marmoratus: Amphibia, Anura, Hyperoliidae) living in unpredictably varying savannah environments.

The regulation of body water balance was examined in the reedfrogs Hyperolius marmoratus taeniatus and Hyperolius viridiflavus ommatostictus. Temperature and stage of post-metamorphic development significantly affected the rate of water uptake. Hydrated reedfrogs prevented hyperhydration by voiding diluted urine when obtaining water. Within 48 hr after rehydration, body fluid osmolality remained at low levels, which may be supportive to counter excessive cutaneous water influx in hydrated frogs. Once evaporative water loss exceeded 10-12% total body mass, reedfrogs became anuric. The rate of water uptake strongly increased with increasing body water deficit. Both the anuric response and the increased rate of water uptake are assumed to strongly enhance the efficacy of using very briefly available water sources during dry-period conditions. Dry-adapted and estivating reedfrogs survived evaporative water losses between 40 and 55% total body mass. Bladder fluid stores contributed substantially to this desiccation tolerance. During a 16-day period of desiccation, H. v. ommatostictus could replace approximately 25% of evaporative water loss from the bladder fluid store. During desiccation, the level of free amino acids selectively increased in the gastrocnemius muscle tissue, which may support cell volume regulation and/or protect cellular structures from osmotic stresses. Even strongly dehydrated reedfrogs rehydrated quickly with no obvious osmoregulatory problem. Rehydration was associated with a higher than expected decrease of free amino acids in the gastrocnemius muscle tissue, a response that may help to protect cells from bursting during fast rehydration.

Amino Acids↗
PubMed1998

Effect of carbohydrates upon insulin secretion in Bufo arenarum (Amphibia:Bufonidae).

Pancreas pieces of Bufo arenarum were incubated with several sugars at basal and stimulatory concentrations, and with inhibitors of their metabolism, measuring the insulin released by radioimmunoassay. Glucose, mannose, fructose, glyceraldehyde and dihydroxyacetone all at 8 mM, significantly enhanced the release of insulin elicited by basal concentrations of these carbohydrates (2 mM). The nonmetabolizable sugars galactose and 2-deoxyglucose failed to enhance insulin secretion. N-Acetyl-glucosamine at 8 mM did not significantly affect the release of insulin. D-Glucose, but not L-glucose, at 8 mM stimulated insulin secretion above baseline (2 mM glucose). At 8 mM, the D-glucose alpha-anomer significantly increased insulin release, while this effect was not observed using the beta-anomer. Insulin release elicited by 2 mM of the alpha-anomer was significantly higher than that triggered by the beta-anomer. Iodoacetate (5 mM), and dinitrophenol (0.3 mM) exerted an inhibitory effect upon glucose-induced insulin secretion. The effect of these carbohydrates and metabolic inhibitors--tested for the first time in amphibians--was similar to that described in the mammalian pancreas, thus suggesting that such compounds play an important role in the metabolic control of insulin secretion in amphibians.

Animals↗
PubMed2000

Allozymic variation of Hynobius kimurae Dunn (Amphibia, Caudata).

An electrophoretic survey was conducted to examine genetic divergence among 21 populations of a lotic-breeding salamander Hynobius kimurae from Honshu, Japan. Genetically H. kimurae proved to be specifically distinct from H. naevius. Hynobius kimurae is divided genetically into two groups of local populations, and the five populations from the eastern area are genetically distinct from the remaining populations of the central and western areas. Less prominent genetic differentiation was revealed between the western and central populations. Separation of the eastern and central-western groups are discussed in relation to the formation of the Japanese mainland.

Animals↗
PubMed1992

Cutaneous venom of Bombina variegata pachypus (Amphibia, Anura): effects on the growth of the human HL 60 cell line.

The effects of Bombina variegata cutaneous venom (Bvv) on eukaryotic cell growth has been assessed employing the human leukaemic cell line HL 60, by liquid and agar semisolid cultures and 51Cr release assay. HL 60 cells growth is impaired by Bvv in a dose-dependent fashion in both culture systems. The arrest of proliferation requires a contact time lower than 3 min and it is not reversed by washing and culturing the cells in a Bvv-free medium. Similarly, an extremely short exposure time is needed to determine maximum 51Cr release. Neither the agar medium nor the fetal calf serum interact with Bvv effects, which, according to the above findings, must be regarded as cytolytic in nature. In both liquid and the agar-semisolid culture Bvv cytolytic activity half life is about 8 hr. The cytolytic properties of Bvv are thought to be part of the chemical defence system of amphibian skin.

Amphibian Venoms↗
PubMed2003

The complete mitochondrial genome of the Chinese giant salamander, Andrias davidianus (Amphibia: Caudata).

The mitochondrial genome of the Chinese giant salamander Andrias davidianus was isolated using the long-and-accurate polymerase chain reaction (LA PCR) method. The sequencing work adopted the shotgun strategy accompanying with seven internal primers to cover the gaps where overlapping clones were not available. The entire mtDNA sequence is 16,503 bp long, with a gene content of 13 protein-coding, two ribosomal RNA and 22 transfer RNA genes, and order identical to that observed in most other vertebrates except for an additional 318 bp non-coding sequence between tRNA-Thr and tRNA-Pro genes. In order to carry out molecular phylogenetic analyses, all 13 protein sequences deduced from whole mitochondrial genomes for eight vertebrate species (six amphibians, two lobe-finned fishes) were combined to a single data set. This data set was refined by the program Gblocks using a stringent parameter setting and then subjected to MP, ML and NJ analyses. Thus phylogenetic relationships among living amphibians were discussed.

Animals↗