Shrew species diversity and abundance in Ziama Biosphere Reserve, Guinea: comparison among primary forest, degraded forest and restoration plots

The aim of our study was to compare the shrew community diversity and structure in gradients of tropical forest degradation and restoration. Four plots within each of six habitats of the Ziama Biosphere Reserve were surveyed, including primary forest, secondary forest, cultivated fields, recently (less than 3 years) abandoned fields, young (10–12 years) forest restoration plots, and old (34 years) restoration plots. From August to November 2003, we pitfall-trapped 2,509 shrews representing 11 species. Shrew species richness and composition was similar in the six habitat surveyed, while shrew species abundance varied between habitats. Canopy height and cover, density of stems and trees and understorey density were shown to constitute important parameters influencing the abundance of several shrew species. After clear-cutting, restoration of key attributes of the forest vegetation structure was possible in 10–34 years, either by natural regeneration or by planting of seedlings. The relative abundance of most shrew species was similar between restoring forest (i.e., young restoration plots or fallows) and primary forest. Considering the advantages and disadvantages of these two methods of forest restoration, one of the most suitable management practices to restore forest while preserving shrew biodiversity could be to perform an alternation of native seedling plantation lines and fallows.     

Comparative production analysis of three phlebovirus nucleoproteins under denaturing or non-denaturing conditions for crystallographic studies

Nucleoproteins (NPs) encapsidate the Phlebovirus genomic (-)RNA. Upon recombinant expression, NPs tend to form heterogeneous oligomers impeding characterization of the encapsidation process through crystallographic studies. To overcome this problem, we set up a standard protocol in which production under both non-denaturing and denaturing/refolding conditions can be investigated and compared. The protocol was applied for three phlebovirus NPs, allowing an optimized production strategy for each of them. Remarkably, the Rift Valley fever virus NP was purified as a trimer under native conditions and yielded protein crystals whereas the refolded version could be purified as a dimer. Yields of trimeric Toscana virus NP were higher from denaturing than from native condition and lead to crystals. The production of Sandfly Fever Sicilian virus NP failed in both protocols. The comparative protocols described here should help in rationally choosing between denaturing or non-denaturing conditions, which would finally result in the most appropriate and relevant oligomerized protein species. The structure of the Rift Valley fever virus NP has been recently published using a refolded monomeric protein and we believe that the process we devised will contribute to shed light in the genome encapsidation process, a key stage in the viral life cycle.     

On the organizing role of nonmuscular forces during performance of a giant circle in gymnastics

Five elite gymnasts performed giant circles on the high bar under different conditions of loading (without and with 6-kg loads attached to the shoulders, waist or ankles). Comparing the gymnasts' kinematic pattern of movement with that of a triple-pendulum moving under the sole influence of nonmuscular forces revealed qualitative similarities, including the adoption of an arched position during the downswing and a piked position during the upswing. The structuring role of nonmuscular forces in the organization of movement was further reinforced by the results of an inverse dynamics analysis, assessing the contributions of gravitational, inertial and muscular components to the net joint torques. Adding loads at the level of the shoulders, waist or ankles systematically influenced movement kinematics and net joint torques. However, with the loads attached at the level of the shoulders or waist, the load-induced changes in gravitational and inertial torques provided the required increase in net joint torque, thereby allowing the muscular torques to remain unchanged. With the loads attached at the level of the ankles, this was no longer the case and the gymnasts increased the muscular torques at the shoulder and hip joints. Together, these results demonstrate that expert gymnasts skillfully exploit the operative nonmuscular forces, employing muscle force only in the capacity of complementary forces needed to perform the task.     

A systematic review of cytogenetic studies conducted in human populations exposed to cadmium compounds

BACKGROUND: Exposure to cadmium fumes or dusts has been associated with an increased risk of lung cancer and the characterisation of the genotoxic potential of cadmium compounds is, among other possible mechanisms, an important element in the assessment of the carcinogenic hazard of the element. While there is some evidence that in experimental systems, cadmium compounds may exert genotoxic effects, the results of the epidemiological studies having examined cytogenetic endpoints in humans exposed to cadmium appear conflicting. Therefore, a systematic review was undertaken to assess whether a cytogenetic effect of cadmium exposure is supported by the studies with the strongest design. METHODS: The relevant literature was identified through several databases and assessed with a check-list by two reviewers. Causes of heterogeneity between studies were looked for. Results were extracted and the strength of the evidence was evaluated with causality criteria. RESULTS: No studies met the criteria for being considered as very convincing. Several factors were identified that could explain contradictory findings (small sample size, selection bias, insufficient characterisation of exposure, lack of consideration of confounders) but their actual impact could not be conclusively assessed with the published information. Importantly, it should be recognised that the absence of a clear mechanism for the cytogenetic action of cadmium compounds did not allow to select the most appropriate endpoint to be examined. CONCLUSIONS: No clear association between cadmium exposure and cytogenetic endpoint appeared but no definite conclusion can be drawn from the existing studies in humans. Future research efforts should mainly focus on experimental studies to understand how cadmium compounds could produce genotoxic/carcinogenic effects, in order to target the most relevant endpoint to be examined in humans.     

Systematics and evolution of the libyan jird based on molecular and morphometric data

The libyan jird is one of the most widely distributed species among wild rodents, with its range extending from Morocco to China. Fifteen subspecies were described but their validity and the phylogenetic relationships among them are uncertain. Based on a comprehensive sampling, this study aims to define subspecies limits within Meriones libycus and to discuss the factors driving subspecific diversification. We used an integrative approach combining molecular (Cytochrome b and Cytochrome Oxidase Subunit 1 genes) and geometric morphometric data. Genetic data allowed us to identify three allopatric lineages within M. libycus: Western lineage in North Africa, Central lineage in Saudi Arabia, Jordan, and Syria, and Eastern lineage in Iran, Afghanistan, and China. These three lineages can also be differentiated based on skull morphology. Our results support the existence of at least three subspecies within the libyan jird: Meriones libycus libycus, M. l. syrius, and Meriones libycus erythrourus. Based on our divergence time estimates, all divergence events within M. libycus probably occurred during the Pleistocene, after 1.597 Ma. Quaternary climate fluctuations in the Sinai Peninsula explain the differentiation between the African M. l. libycus and the Levant-Arabian M. l. syrius. The differentiation of M. l. syrius with respect to the eastern M. l. erythrourus is putatively linked to the climatic fluctuations and tectonic activity of the Zagros Mountains and/or the Mesopotamia Plain of Iraq during the Pleistocene.     

Isolation and characterization of polymorphic microsatellite loci in two primary parasitoids of the noctuid Spodoptera frugiperda: Chelonus insularis and Campoletis sonorensis (Hymenoptera)

Fifteen and 13 microsatellite loci were isolated, respectively, from Campoletis sonorensis Cameron and from Chelonus insularis Cresson. These two parasitic Hymenoptera are primary parasitoids of Lepidoptera in North, Central and South America, including the important agricultural pest Spodoptera frugiperda. Allelic diversity and heterozygosity were quantified in samples from Mexico. Each locus was polymorphic, with the number of alleles ranging from two to 16 in C. sonorensis and from four to 18 in C. insularis. Heterozygosity ranged from 0.088 to 0.403 in C. sonorensis and from 0.106 to 0.458 in C. insularis.