In central Europe, the hybridogenetic waterfrog Rana esculenta, a hybrid between Rana ridibunda and Rana lessonae, lives in sympatry with one of its parental species, the poolfrog Rana lessonae. As R. esculenta has to backcross constantly with R. lessonae in order to produce viable offspring, this coexistence is obligatory for R. esculenta. Since R. esculenta has a higher primary fitness than R...

In the present study, we investigated the induction of the p38-MAPK signalling pathway by copper, as exemplified by CuCl(2), in the isolated perfused heart of the amphibian Rana ridibunda. We found that p38-MAPK phosphorylation by CuCl(2) occurs in a dose-dependent manner, with maximum activation (8.73+/-1.43-fold relative to control values) attained by perfusion with 500 micromol l(-1) CuCl(2)...

A high-performance liquid chromatography nano-electrospray ionization Fourier transform mass spectrometry (HPLC/nanoESI-FTMS) approach involving recording of collision-activated dissociation (CAD) and electron-capture dissociation (ECD) spectra of an intact sample and two its modifications after performic oxidation and reduction followed by carboxamidomethylation helps to establish peptide prof...

Abstract.-Spontaneous deleterious mutations are expected to accumulate through Muller's ratchet in clonally reproducing organisms and may lead to their extinction. We study deleterious mutations and their effects in a system of European frogs. Rana esculenta (RL), natural hybrids R. ridibunda (RR) X R. lessonae (LL), reproduce hemiclonally; both sexes exclude the L genome in the germ line and p...