Sex-specific estimates of dispersal show female philopatry and male dispersal in a promiscuous amphibian, the alpine salamander (Salamandra atra).

Amphibians display wide variations in life-history traits and life cycles that should prove useful to explore the evolution of sex-biased dispersal, but quantitative data on sex-specific dispersal patterns are scarce. Here, we focused on Salamandra atra, an endemic alpine species showing peculiar life-history traits. Strictly terrestrial and viviparous, the species has a promiscuous mating system, and females reproduce only every 3 to 4 years. In the present study, we provide quantitative estimates of asymmetries in male vs. female dispersal using both field-based (mark-recapture) and genetic approaches (detection of sex-biased dispersal and estimates of migration rates based on the contrast in genetic structure across sexes and age classes). Our results revealed a high level of gene flow among populations, which stems exclusively from male dispersal. We hypothesize that philopatric females benefit from being familiar with their natal area for the acquisition and defence of an appropriate shelter, while male dispersal has been secondarily favoured by inbreeding avoidance. Together with other studies on amphibians, our results indicate that a species' mating system alone is a poor predictor of sex-linked differences in dispersal, in particular for promiscuous species. Further studies should focus more directly on the proximate forces that favour or limit dispersal to refine our understanding of the evolution of sex-biased dispersal in animals.

Electrospun scaffolds functionalized with heparin and vascular endothelial growth factor increase the proliferation of endothelial progenitor cells.

In severe cases of peripheral arterial disease, tissue loss can occur and the use of vascular grafts can be necessary. However, currently, there are no suitable substitutes for application in small diameter vessels. The aim of this work has been to produce scaffolds with adequate properties for application as vascular substitutes. Polycaprolactone scaffolds were produced by the electrospinning technique. The surface of the scaffolds was functionalized with heparin and vascular endothelial growth factor (VEGF) and their physical-chemical properties were characterized. Human endothelial progenitor cells (EPCs) or mesenchymal stem cells (MSCs) were seeded onto the surface of the scaffolds in order to create an endothelial layer. The electrospun scaffolds exhibited mechanical properties compatible with the native arteries. The presence of heparin prevented blood coagulation on the scaffold surface. The presence of heparin and VEGF favored the adaptation of MSCs and EPCs on the scaffolds in relation to the non functionalized scaffolds. In addition, the EPCs cultivated on the scaffolds maintained the expression of CD31, CD34 and VE-cadherin genes. The results obtained in the present study suggest that electrospun scaffolds functionalized with heparin and VEGF can be applied in vascular tissue engineering. These scaffolds exhibited antithrombogenic properties and favored the development of cells on their surface. The association of heparin and VEGF with electrospun scaffolds increased EPC proliferation, favoring the formation of the endothelial layer and the regeneration of damaged vessels.

Anxiogenic-like consequences in animal models of complex partial seizures.

Several kinds of psychiatric symptoms (anxiety, depression, schizophrenia) have been associated with epilepsies, and clinical data suggest that patients with seizures involving limbic structures are the most prone to develop behavioural disorders between the seizures (i.e. interictally). Studying the neurobiological mechanisms that underlie these symptoms is difficult in humans because of different interfering factors (e.g. psychosocial difficulties, pharmacological side-effects, lesions), which can be avoided in animal models. Using repetitive electrical stimulations (kindling) or local applications of a neuroexcitotoxin in limbic structures (mainly the amygdala and hippocampus), several authors have reported lasting changes of emotional reactivity in cats and rats. These changes appear as anxiety-related reactions expressed as a hyperdefensiveness in the cat, or a reduction of spontaneous exploration in tests predictive of anxiogenic effects in the rat. Some neuroplasticity processes known to develop during epileptogenesis (neuronal-hyperexcitability, modulation of GABA/benzodiazepine transmission) may participate in these lasting changes of behaviour, especially in structures involved in the control of fear-promoted reactions (amygdala, periaqueductal grey matter). In addition, endogenous control systems may also play a critical role in the occurrence of interictal behavioural disorders.

Amygdala kindling in the rat: anxiogenic-like consequences.

Patients with complex partial seizures of temporal lobe origin may experience behavioural disorders like depressive, anxiety-related or schizophrenic-like symptoms between seizures, i.e. interictally. The neural mechanisms underlying these enduring interictal disorders remain to be investigated. The aim of the present study was to examine the behavioural consequences of kindling of the basolateral nuclei of the amygdala, an animal model of limbic complex partial seizures. Animals having experienced 15 stage 5 seizures were compared to non-kindled controls in different behavioural tests performed at least seven days after the last seizure. Kindled animals showed a significant reduction of exploration of open arms in the elevated plus-maze test. In the social interactions test, they showed a decrease of non-social behaviour and an increase of immobility. No modifications were observed in kindled animals when tested in the open field, the sucrose preference or the forced swimming test. The reduction of open arm exploration in the elevated plus-maze was reversed by a pretreatment with chlordiazepoxide (2 mg/kg i.p.), a benzodiazepine anxiolytic. Finally, a similar reduction of open arm exploration was observed when animals were kindled only until a stage 3 seizure occurred. These data, along with previous studies, suggest that kindling of the amygdala has anxiogenic consequences and provide an animal model to study the neuroplasticity phenomena underlying enduring interictal disorders in humans.

Phylogeography and Pleistocene refugia of the adder (Vipera berus) as inferred from mitochondrial DNA sequence data.

In order to contribute to the debate about southern glacial refugia used by temperate species and more northern refugia used by boreal or cold-temperate species, we examined the phylogeography of a widespread snake species (Vipera berus) inhabiting Europe up to the Arctic Circle. The analysis of the mitochondrial DNA (mtDNA) sequence variation in 1043 bp of the cytochrome b gene and in 918 bp of the noncoding control region was performed with phylogenetic approaches. Our results suggest that both the duplicated control region and cytochrome b evolve at a similar rate in this species. Phylogenetic analysis showed that V. berus is divided into three major mitochondrial lineages, probably resulting from an Italian, a Balkan and a Northern (from France to Russia) refugial area in Eastern Europe, near the Carpathian Mountains. In addition, the Northern clade presents an important substructure, suggesting two sequential colonization events in Europe. First, the continent was colonized from the three main refugial areas mentioned above during the Lower-Mid Pleistocene. Second, recolonization of most of Europe most likely originated from several refugia located outside of the Mediterranean peninsulas (Carpathian region, east of the Carpathians, France and possibly Hungary) during the Mid-Late Pleistocene, while populations within the Italian and Balkan Peninsulas fluctuated only slightly in distribution range, with larger lowland populations during glacial times and with refugial mountain populations during interglacials, as in the present time. The phylogeographical structure revealed in our study suggests complex recolonization dynamics of the European continent by V. berus, characterized by latitudinal as well as altitudinal range shifts, driven by both climatic changes and competition with related species.

Estudio comparativo de dos modalidades de arterialización de las venas del pie en isquemia crítica / Comparative study of two techniques for arteriolization of the feet veins in critical isquemia

De Febrero de 1974 a Julio de 1992 se han realizado 29 arterializaciones de la red venosa del pie en 28 arterioáticos en estado IIIB o IV, con lesiones ateromatosas diseminadas femoropopliteas y por debajo de la rodilla, que imposibilitan la revascularización con bypass clásico. Los pacientes fueron dividos en dos grupos. El primero comprende 8 operados con un bypass de arterialización anastomosado distalmente (fístula) en término-terminal a la safena interna en el tercio distal de la pierna y otro bypass de descarga en el dorso del pie,entre la vena marginal interna y la safena externa retromaleolar. El segundo grupo esta constituido de 21 arterializaciones con un solo bypass anastomosado distalmente en termino-lateral a una vena del pie. Este grupo se ha benefifiado en el preoperatorio de una flebografía a contra corriente del pie y del empleo de un material mejor adaptado para la destrucción de las válvulas venosas. Las fístulas generalmente han evolucionado hacia la obliteración espontánea, pero, entre tanto, induciendo una circulación colateral capaz de mantener el beneficio de la operación a largo plazo