The effects of drift and selection on latitudinal genetic variation in Scandinavian common toads (Bufo bufo) following postglacial recolonisation

Clinal variation is paramount for understanding the factors shaping genetic diversity in space and time. During the last glacial maximum, northern Europe was covered by glacial ice that rendered the region uninhabitable for most taxa. Different evolutionary processes during and after the recolonisation of this area from different glacial refugia have affected the genetic landscape of the present day European flora and fauna. In this study, we focus on the common toad (Bufo bufo) in Sweden and present evidence suggesting that these processes have resulted in two separate lineages of common toad, which colonised Sweden from two directions. Using ddRAD sequencing data for demographic modelling, structure analyses, and analysis of molecular variance (AMOVA), we provide evidence of a contact zone located between Uppland and Västerbotten in central Sweden. Genetic diversity was significantly higher in southern Sweden compared to the north, in accordance with a pattern of decreased genetic diversity with increasing distance from glacial refugia. Candidate genes under putative selection are identified through outlier detection and gene–environment association methods. We provide evidence of divergent selection related to stress response and developmental processes in these candidate genes. The colonisation of Sweden by two separate lineages may have implications for how future conservation efforts should be directed by identifying management units and putative local adaptations.Subject terms: Evolutionary genetics, Genomics, Genetic variation     

Mouse atrio-ventricular valve ultrastructure morphometrical correlations

Morphometric data on mouse atrio-ventricular valve ultrastructure are reported. The statistical analysis of the volumetric density percentage for cellular and extracellular valve components and of endothelial plasmalemmal vesicle density for the different endocardial domains (atrial, valvular and ventricular) showed: the bicuspid compared to the tricuspid valve has a more important lymphatic drainage, less vascularization, higher endothelial plasmalemmal vesicle density and more macrophages, striated muscle cells and collagen along with fewer interstitial cells, nervous terminals and elastin in the leaflet; the valvular endothelium as compared to other endocardial domains has a higher density of plasmalemmal vesicles, considering the results for both endothelial fronts (luminal and abluminal).     

Excessive exercise training causes mitochondrial functional impairment and decreases glucose tolerance in healthy volunteers

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Regulation of Bacterial Cell Division: Genetic and Phenotypic Analysis of Temperature-Sensitive, Multinucleate, Filament-Forming Mutants of Escherichia coli

Three mutants of Escherichia coli K-12 which form filaments during 42 C incubation have been characterized. The mutant strains AX621, AX629, and AX655 continued to grow and to synthesize deoxyribonucleic acid at 42 C for 150 to 180 min, after which time growth ceased. When cultures of the mutants were transferred from 42 to 28 C, septation of the filaments began after a 25- to 30-min period and continued at a greater than normal rate until no filaments remained. Addition of chloramphenicol at the time of transfer from 42 to 28 C prevented cell division in strain AX655 and caused lysis of strains AX621 and AX629. The temperature sensitivity mutation in each strain mapped near leu. For strain AX621, the mutation was specifically located between leu and nadC by P1 transduction. Properties of these strains are compared with those of other cell division mutants.