BH3-only protein Bim inhibits activity of antiapoptotic members of Bcl-2 family when expressed in yeast

Proteins of the Bcl-2 family regulate programmed cell death in mammals by promoting the release of cytochrome c from mitochondria in response to various proapoptotic stimuli. The mechanism by which BH3-only members of the family activate multidomain proapoptotic proteins Bax and Bak to form a pore in mitochondrial membranes remains under dispute. We report that cell death promoting activity of BH3-only protein Bim can be reconstituted in yeast when both Bax and antiapoptotic protein Bcl-X(L) are present, suggesting that Bim likely activates Bax indirectly by inhibiting antiapoptotic proteins.     

Gut bacteria-derived 5-hydroxyindole is a potent stimulant of intestinal motility via its action on L-type calcium channels

Microbial conversion of dietary or drug substrates into small bioactive molecules represents a regulatory mechanism by which the gut microbiota alters intestinal physiology. Here, we show that a wide variety of gut bacteria can metabolize the dietary supplement and antidepressant 5-hydroxytryptophan (5-HTP) to 5-hydroxyindole (5-HI) via the tryptophanase (TnaA) enzyme. Oral administration of 5-HTP results in detection of 5-HI in fecal samples of healthy volunteers with interindividual variation. The production of 5-HI is inhibited upon pH reduction in in vitro studies. When administered orally in rats, 5-HI significantly accelerates the total gut transit time (TGTT). Deciphering the underlying mechanisms of action reveals that 5-HI accelerates gut contractility via activation of L-type calcium channels located on the colonic smooth muscle cells. Moreover, 5-HI stimulation of a cell line model of intestinal enterochromaffin cells results in significant increase in serotonin production. Together, our findings support a role for bacterial metabolism in altering gut motility and lay the foundation for microbiota-targeted interventions.     

Long-distance Eurasian lynx dispersal – a prospect for connecting native and reintroduced populations in Central Europe

Dispersal is a key process for the maintenance of intraspecific genetic diversity by ensuring gene flow within and between populations. Despite the ongoing expansion of large carnivores in Europe, lynx populations remain fragmented, isolated, and threatened by inbreeding and loss of genetic diversity. In the course of large carnivore monitoring in the Czech Republic, several biological samples of Eurasian lynx were collected outside the permanent occurrence of this species. Using microsatellite genotyping we identified these as four dispersing lynx males and applied multiple methods (Bayesian clustering in STRUCTURE, Principal Component Analysis (PCA), frequency-based method in GENECLASS2, and machine-learning framework in assignPOP) to assign them to possible source populations. For this we used genotypes from five European lynx populations: the Bohemian-Bavarian-Austrian (N?=?36), Carpathian (N?=?43), Scandinavian (N?=?20), Baltic (N?=?15), and Harz (N?=?23) population. All four dispersers were successfully assigned to different source populations within Europe and each was recorded at a distance of more than 98 km from the edge of the distribution of the source population identified. Such movements are among the longest described for lynx in Central Europe to this point. The findings indicate the ability of lynx males to disperse in human-dominated landscape thus facilitation of these movements via creation and/or protection of potential migratory corridors together with protection of dispersing individuals should be of high importance in conservation of this iconic predator in Central Europe.

     

Social and life history correlates of litter size in captive colonies of precocial spiny mice (<Emphasis Type="Italic">Acomys</Emphasis>)

Litter size is an important component of life history contributing to reproductive success in many animals. Among muroid rodents, spiny mice of the genus Acomys are exceptional because they produce large precocial offspring after a long gestation. We analyzed data on 1,809 litters from laboratory colonies of spiny mice from the cahirinus-dimidiatus group: Acomys cahirinus, Acomys cilicicus, Acomys sp. (Iran), and Acomys dimidiatus. Generalized mixed-effect models revealed that litter size increased with maternal body weight and/or number of immature females present in the family group. Thus, both maternal body reserves and presence of immature descendants demonstrating previous reproductive success enhance further reproduction in this social rodent.     

Anisops sardeus (Heteroptera): A new expansive species in Central Europe

Although insects form a large part of the aquatic fauna worldwide, expansive species of aquatic insects are quite rare. Recently, we can observe a tendency to the range expansions in several aquatic insect species. Here, we present the first record of water bug species Anisops sardeus sardeus (Heteroptera: Notonectidae) from Slovakia. This is the northernmost record of this small-bodied backswimmer which is native to Sahelo-Sindian area, extending to Mediterranean. However, the species shows recent range expansion northward in Europe. We document the current distribution of A. s. sardeus in Slovakia and Europe, and discuss the drivers of expansion and possible impact of the alien species on resident fauna.     

Geographical parthenogenesis, genome size variation and pollen production in the arctic-alpine species Hieracium alpinum

Hieracium alpinum L. (Asteraceae) is an arctic-alpine species distributed throughout Europe with both diploid and triploid cytotypes. We determined the ploidy levels of plants from 23 populations from Austria, Bosnia and Herzegovina, Finland, Italy, Norway, Romania, Slovakia, Switzerland and Ukraine. Data showed a non-overlapping pattern of cytotype distribution: sexually reproducing diploids (2n = 2x = 18) occur solely in the Eastern and Southern Carpathians, while apomictic triploids (2n = 3x = 27) cover the rest of the range. Such clear-cut allopatry is rather rare in vascular plants with geographical parthenogenesis. Comparison of absolute genome size indicates genome downsizing (by on average 3.7%) of haploid DNA amount in triploids relative to diploids. Genome size further correlated with longitude and latitude in the Alps, with decreasing absolute DNA content from west to east, and from south to north. While previously published data indicated complete male sterility of triploid plants, we found that plants from the Alps and Bosnia and Herzegovina commonly produced some pollen, whereas populations from the Western Carpathians and Scandinavia seemed to be almost completely pollen sterile. Scenarios about the evolution of geographical parthenogenesis in H. alpinum are discussed.

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Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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Résumé   Hieracium alpinum L. (au sens strict) est une espèce arctique-alpine d’aire de répartition très large, comprenant les régions nordiques (le Groenland, l’Islande, l’Ecosse, la Scandinavie et le nord de la Russie) et les montagnes de l’Europe continentale (les Alpes, les Carpates, les Sudètes, les Vosges et le plateau de Vranica). Dans cette étude, nous avons compté le nombre chromosomique et estimé la plo?die par cytométrie de flux de plantes provenant de 23 populations échantillonnées en Autriche, Bosnie et Herzégovine, Finlande, Italie, Norvège, Roumanie, Slovaquie, Suisse et Ukraine. Ces données et celles de la littérature montrent une nette séparation spatiale entre deux cytotypes différents: Les populations diplo?des sexuées sont réparties uniquement dans les Carpates orientales et occidentales (Roumanie et Ukraine), tandis que les populations triplo?des apomictiques occupent l’aire de répartition restante. Ce type d’allopatrie stricte est rare chez les plantes avec parthénogenèse géographique. En comparant la taille du génome haplo?de (1Cx) des plantes triplo?des avec celui des plantes diplo?des, nous avons identifié une sensible réduction de taille du génome polyplo?de (la divergence moyenne est 3.7%). Parmi les plantes triplo?des, les individus du plateau de Vranica (Bosnie et Herzégovine) ont significativement moins d’ADN que les triplo?des provenant des Alpes ou des Carpates occidentales (2C = 10.28 pg d’ADN contre 11.02 et 10.93 pg, respectivement). Une corrélation significative entre la taille du génome et la longitude et la latitude a été révélée dans les Alpes, avec des valeurs décroissantes d’ouest en est, et du sud vers le nord. Tandis que les données publiées indiquaient une stérilité male complète chez les triplo?des, nous avons trouvé des plantes triplo?des provenant des Alpes et du plateau de Vranica produisant du pollen, bien qu’en faible quantité et de taille hétérogène. Divers scénarios sur l’évolution de la parthénogénèse géographique chez H. alpinum sont discutés à la lumière de ces nouveaux résultats.