Adjacent woodlands rather than habitat connectivity influence grassland plant,carabid and bird assemblages in farmland landscapes

One response to biodiversity decline is the definition of ecological networks that extend beyond protected areas and promote connectivity in human-dominated landscapes. In farmland, landscape ecological research has focused more on wooded than open habitat networks. In our study, we assessed the influence of permanent grassland connectivity, described by grassland amount and spatial configuration, on grassland biodiversity. We selected permanent grasslands in livestock farming areas of north-western France, which were sampled for plants, carabids and birds. At two spatial scales we tested the effects of amount and configuration of grasslands, wooded habitats and crops on richness and abundance of total assemblages and species ecological groups. Grassland connectivity had no significant effects on total richness or abundance of any taxonomic group, regardless of habitat affinity or dispersal ability. The amount of wooded habitat and length of wooded edges at the 200 m scale positively influenced forest and generalist animal groups as well as grassland plant species, in particular animal-dispersed species. However, for animal groups such as open habitat carabids or farmland bird specialists, the same wooded habitats negatively influenced richness and abundance at the 500 m scale. The scale and direction of biodiversity responses to landscape context were therefore similar among taxonomic groups, but opposite for habitat affinity groups. We conclude that while grassland connectivity is unlikely to contribute positively to biodiversity, increasing or maintaining wooded elements near grasslands would be a worthwhile conservation goal. However, the requirements of open farmland animal species groups must be considered, for which such action may be deleterious.     

Étude craniométrique du complexe d’espèces Meriones shawii–grandis (Mammalia : Rodentia) au Maroc,en Algérie et en Tunisie

In North Africa, the rodents of the species complex Meriones shawii–grandis have a considerable ecological, economic and epidemiological importance. Until now, the systematics of these species was subject to discussion due to the presence of populations displaying high morphological variability. By means of an approach of traditional morphometrics based on cranial distances and by using the method of the log shape-ratio, we attempt to characterize morphologically these two taxa. The results show significant differences in size and shape between the specimens of Morocco, on the one hand, and those of Algeria and Tunisia, on the other hand. The samples of Morocco that have been molecularly typed and attributed to M. grandis have larger tooth rows and narrower skulls, as well as relatively small tympanic bullae. On the other hand, those of Algeria and Tunisia assigned to M. shawii are characterized by small tooth rows and wide skulls with well-developed tympanic bullae. The morphological distance is relatively strong between both clades (79.5%), which corresponds to the molecular distance. However, the discriminant analysis performed after molecularly-typed specimens allows the correct classification of only 91.8% of the individuals.     

Phylogeography and historical demography of the Lusitanian snail <Emphasis Type="Italic">Elona quimperiana</Emphasis> reveal survival in unexpected separate glacial refugia

Background  

Present day distributions of Palearctic taxa in northern latitudes mainly result from populations having survived in local patches during the Late Pleistocene and/or from recolonizing populations from southern temperate refugia. If well-studied Mediterranean and eastern European refugia are widely accepted, some recent biogeographical assumptions still remain unclear, such as the occurrence of multiple glacial refugia in Iberia and cryptic refugia in northern Europe during the last glaciations. The Lusitanian snail Elona quimperiana has a remarkably disjunct distribution, limited to northwestern France (Brittany), northwestern Spain and the Basque Country. By describing the phylogeographical structure of this species across its entire range, the present study attempts to identify refugia and subsequent recolonization routes.     

A forward chemical genetic screen reveals an inhibitor of the Mre11-Rad50-Nbs1 complex

The MRN (Mre11-Rad50-Nbs1)-ATM (ataxia-telangiectasia mutated) pathway is essential for sensing and signaling from DNA double-strand breaks. The MRN complex acts as a DNA damage sensor, maintains genome stability during DNA replication, promotes homology-dependent DNA repair and activates ATM. MRN is essential for cell viability, which has limited functional studies of the complex. Small-molecule inhibitors of MRN could circumvent this experimental limitation and could also be used as cellular radio- and chemosensitization compounds. Using cell-free systems that recapitulate faithfully the MRN-ATM signaling pathway, we designed a forward chemical genetic screen to identify inhibitors of the pathway, and we isolated 6-(4-hydroxyphenyl)-2-thioxo-2,3-dihydro-4(1H)-pyrimidinone (mirin, 1) as an inhibitor of MRN. Mirin prevents MRN-dependent activation of ATM without affecting ATM protein kinase activity, and it inhibits Mre11-associated exonuclease activity. Consistent with its ability to target the MRN complex, mirin abolishes the G2/M checkpoint and homology-dependent repair in mammalian cells.     

Structures of P. falciparum protein kinase 7 identify an activation motif and leads for inhibitor design

Malaria is a major threat to world health. The identification of parasite targets for drug development is a priority and parasitic protein kinases suggest themselves as suitable targets as many display profound structural and functional divergences from their host counterparts. In this paper, we describe the structure of the orphan protein kinase, Plasmodium falciparum protein kinase 7 (PFPK7). Several Plasmodium protein kinases contain extensive insertions, and the structure of PFPK7 reveals how these may be accommodated as excursions from the canonical eukaryotic protein kinase fold. The constitutively active conformation of PFPK7 is stabilized by a structural motif in which the role of the conserved phosphorylated residue that assists in structuring the activation loop of many protein kinases is played by an arginine residue. We identify two series of PFPK7 ATP-competitive inhibitors and suggest further developments for the design of selective and potent PFPK7 lead compounds as potential antimalarials.     

Mutations in CNNM4 Cause Recessive Cone-Rod Dystrophy with Amelogenesis Imperfecta

Cone-rod dystrophies are inherited dystrophies of the retina characterized by the accumulation of deposits mainly localized to the cone-rich macular region of the eye. Dystrophy can be limited to the retina or be part of a syndrome. Unlike nonsyndromic cone-rod dystrophies, syndromic cone-rod dystrophies are genetically heterogeneous with mutations in genes encoding structural, cell-adhesion, and transporter proteins. Using a genome-wide single-nucleotide polymorphism (SNP) haplotype analysis to fine map the locus and a gene-candidate approach, we identified homozygous mutations in the ancient conserved domain protein 4 gene (CNNM4) that either generate a truncated protein or occur in highly conserved regions of the protein. Given that CNNM4 is implicated in metal ion transport, cone-rod dystrophy and amelogenesis imperfecta may originate from abnormal ion homeostasis.     

Activation and catalysis of the di-heme cytochrome c peroxidase from Paracoccus pantotrophus

Bacterial cytochrome c peroxidases contain an electron transferring (E) heme domain and a peroxidatic (P) heme domain. All but one of these enzymes are isolated in an inactive oxidized state and require reduction of the E heme by a small redox donor protein in order to activate the P heme. Here we present the structures of the inactive oxidized and active mixed valence enzyme from Paracoccus pantotrophus. Chain flexibility in the former, as expressed by the crystallographic temperature factors, is strikingly distributed in certain loop regions, and these coincide with the regions of conformational change that occur in forming the active mixed valence enzyme. On the basis of these changes, we postulate a series of events that occur to link the trigger of the electron entering the E heme from either pseudoazurin or cytochrome c(550) and the dissociation of a coordinating histidine at the P heme, which allows substrate access.