The biosynthesis of urea in vifro was maintained at a constant rate for 48 hours in a surviving amphibian liver cube system. The maintenance of constant oxygen consumption and protein synthesis during this time indicated that the majority of cells remained viable. A direct correlation between the rate of lixation of 14C02 and ammonia into urea and the levels of carbamyl phosphate synthetase in ...

The ribonuclease inhibitor (RI) is a cytosolic protein and a potent inhibitor of bovine pancreatic ribonuclease (RNase A). Amphibian homologues and variants of RNase A that evade RI are cytotoxic. Here, we employ RNA interference along with amphibian and mammalian ribonucleases to demonstrate that RI protects cells against exogenous ribonucleases. These data indicate an imperative for the molec...

............................................................................................................................................... iii Acknowledgements ......................................................................................................................... iv . Introduction ..............................................................................................

As one progresses from the most primitive to the most derived frogs, one observes remarkable changes in that peculiarly amphibian auditory organ, the amphibian papilla. In all but the most primitive frog, the papilla comprises two patches with separate innervation and apparently corresponding to a spatial separation of frequency sensitivity (i.e. tonotopic organization). The caudal patch is qui...

Amphibians are declining worldwide for a variety of reasons, including habitat alteration, introduction of non-native species, disease, climate change, and environmental contaminants. Amphibians often play important roles in structuring ecosystems, and, as a result, amphibian population declines or extinctions are likely to affect other trophic levels (Matthews and others 2002). Avoiding declin...

Disease can be an important driver of host population dynamics and epizootics can cause severe host population declines. Batrachochytrium dendrobatidis (Bd), the pathogen causing amphibian chytridiomycosis, may occur epizootically or enzootically and can harm amphibian populations in many ways. While effects of Bd epizootics are well documented, the effects of enzootic Bd have rarely been descr...

Interferons (IFNs) are key cytokines identified in vertebrates and evolutionary dominance of intronless IFN genes in amniotes is a signature event in IFN evolution. For the first time, we show that the emergence and expansion of intronless IFN genes is evident in amphibians, shown by 24-37 intronless IFN genes in each frog species. Amphibian IFNs represent a molecular complex more complicated t...

Global amphibian decline by chytridiomycosis is a major environmental disaster that has been attributed to either recent fungal spread or environmental change that promotes disease. Here, we present a population genetic comparison of Batrachochytrium dendrobatidis isolates from an intensively studied region of frog decline, the Sierra Nevada of California. In support of a novel pathogen, we fin...