On the analysis of hand synergies during grasping in weightlessness

The aim of this paper was to analyse how the strategies implemented by the Central Nervous System to control the hand during grasping are modified under microgravity conditions. Two right-handed subjects carried out simple grasping tasks during parabolic flights. The trajectories of the fingers of the hand were recorded using a sensorised glove and processed in order to extract a variable (here indicated as K) which can indicated the degree of synergies existing among the fingers. The results showed that K was quite small during the trial at 1g while becoming significantly greater than 1 during the first parabolas. Then, the value k decreased to the values at 1 g after some parabolas. These results suggested a possible adaptation process of the manipulation abilities during the permanence at 0g conditions. Future extensive trials will be performed in order to confirm these preliminary results.     

Microarray RNA quantification assay for large-scale nanosamples analysis.

We have developed a convenient and sensitive method for the quantification of RNA in samples from microbiopsies. This procedure is especially suitable for quantitating very small amounts of RNA in large-scale biological samples. This method, using a microarray-spotting facility for the study of multigenic expression, entails the hybridization of a DNA probe with RNA spotted at high density on nylon membrane. Furthermore, with this procedure, the reproducibility, sensitivity, and accuracy of the assay are notably improved as compared to current methods.     

Continental faunal exchange and the asymmetrical radiation of carnivores

Lineages arriving on islands may undergo explosive evolutionary radiations owing to the wealth of ecological opportunities. Although studies on insular taxa have improved our understanding of macroevolutionary phenomena, we know little about the macroevolutionary dynamics of continental exchanges. Here we study the evolution of eight Carnivora families that have migrated across the Northern Hemisphere to investigate if continental invasions also result in explosive diversification dynamics. We used a Bayesian approach to estimate speciation and extinction rates from a substantial dataset of fossil occurrences while accounting for the incompleteness of the fossil record. Our analyses revealed a strongly asymmetrical pattern in which North American lineages invading Eurasia underwent explosive radiations, whereas lineages invading North America maintained uniform diversification dynamics. These invasions into Eurasia were characterized by high rates of speciation and extinction. The radiation of the arriving lineages in Eurasia coincide with the decline of established lineages or phases of climate change, suggesting differences in the ecological settings between the continents may be responsible for the disparity in diversification dynamics. These results reveal long-term outcomes of biological invasions and show that the importance of explosive radiations in shaping diversity extends beyond insular systems and have significant impact at continental scales.     

Seasonal and spatial variability of elemental concentrations in boreal forest larch foliage of Central Siberia on continuous permafrost

We measured the seasonal dynamics of major and trace elements concentrations in foliage of larch, main conifer species of Siberia, and we analyzed cryogenic soils collected in typical permafrost-dominated habitats in the Central Siberia. This region offers a unique opportunity to study element fractionation between the soil and the plant because of (i) the homogeneous geological substratum, (ii) the monospecific stands (Larix gmelinii) and (iii) the contrasted habitats (North-facing slope, South-facing slope, and Sphagnum peatbog) in terms of soil temperature, moisture, thickness of the active layer, tree biomass and rooting depth. The variation of these parameters from one habitat to the other allowed us to test the effects of these parameters on the element concentration in larch foliage considered with high seasonal resolution. Statistical treatment of data on larch needles collected 4 times in 3 locations during entire growing season (June–September) demonstrated that : (1) there is a high similarity of foliar chemical composition of larch trees in various habitats suggesting intrinsically similar requirements of larch tree growth for nutrients, (2) the variation of elemental concentrations in larch needles is controlled by the period (within the growing season) and not by the geographical location (South-facing slope, North-facing slope or bog zone) and (3) there are three groups of elements according to their patterns of elements concentration in needles over the growing season from June to September can be identified: (1): nutrient elements [P, Cu, Rb, K, B, Na, Zn, Ni and Cd] showing a decrease of concentration from June to September similar to the behaviour of major nutrients such as N, P and K; (2): accumulating elements [Ca, Mg, Mo, Co, Sr, Mn, Pb and Cr] showing an increase of concentration from June–July to September; (3): indifferent elements [Al, Zr, Fe, Ba, Ti, REEs (Pr, Nd, Ce, La, Gd, Er, Dy, Tb, Lu, Yb, Tm, Sm, Ho, Eu), Y, Th and U] showing a decrease of concentration from June to July and then an increase of concentration to September. A number of micronutrients (e.g., Cu, Zn) demonstrate significant resorption at the end of growing season suggesting possible limitation by these elements. Although the intrinsic requirement seems to be similar among habitats, the total amount of element stored within the different habitats is drastically different due to the differences in standing tree biomass. The partitioning coefficients between soil and larch appear to be among the lowest compared to other environments with variable plants, soils and climates. Applying the “space for time” substitution scenario, it follows that under ongoing climate warming there will be an increase of the element stock following enhanced above-ground biomass accumulation, even considering zero modification of element ratios and their relative mobility. In this sense, the habitats like south-facing slopes can serve as resultant of climate warming effect on element cycling in larch ecosystems for the larger territory of Central Siberia.