Terrestrial isopods from the Oued Laou basin,north-eastern Morocco (Crustacea: Oniscidea), with descriptions of two new genera and seven new species

Thirty-four species of terrestrial isopods (Crustacea: Oniscidea) from the Oued Laou basin, in the Rif area of north-eastern Morocco, are recorded. One genus (Paractenoscia) and seven species (Trichoniscus microphthalmus, Paractenoscia cavernicola, Bathytropa rifensis, Soteriscus gibbosus, S. laouensis, Porcellio pseudornatus, and Eluma praticola) are described as new. The genus Soteriscus, unavailable according to article 13.3 of the International Commission on Zoological Nomenclature (ICZN), is here revalidated by choosing S. gaditanus as type species. Six species (Graeconiscus thermophilus, Ctenoscia minima, Platyarthrus parisii, Porcellio humberti, Porcellio flavocinctus and Eluma caelata) have been fully illustrated to facilitate their identifications. Ctenoscia dorsalis Verhoeff is considered to be a junior synonym of C. minima Dollfus. Porcellio ornatus from southern Spain is also figured for comparison with P. pseudornatus sp. nov. The composition and origin of the oniscidean fauna of the Rif region is briefly discussed.

http://zoobank.org/urn:lsid:zoobank.org:pub:DCBF3103-1463-4A32-9BC0-A4CFE8B762AE     

The Academic Journal Ranking Problem: A Fuzzy-Clustering Approach

The Academic Journal Ranking Problem consists in formulating a formal assessment of scientific journals. An outcome variable must be constructed that allows valid journal comparison, either as a set of tiers (ordered classes) or as a numerical index. But part of the problem is also to devise a procedure to get this outcome, that is, how to get and use relevant data coming from expert opinions or from citations database. We propose a novel approach to the problem that applies fuzzy cluster analysis to peer reviews and opinion surveys. The procedure is composed of two steps: the first is to collect the most relevant qualitative assessments from international organizations (for example, the ones available in the Harzing database) and, as inductive analysis, to apply fuzzy clustering to determine homogeneous journal classes; the second deductive step is to determine the hidden logical rules that underlies the classification, using a classification tree to reproduce the same patterns of the first step.     

Alternative synthetic route for the heterometallic CO-releasing [Sb@Rh12(CO)27]3− icosahedral carbonyl cluster and synthesis of its new unsaturated [Sb@Rh12(CO)24]4− and dimeric [{Sb@Rh12Sb(CO)25}2Rh(CO)2PPh3]7− derivatives

The hetero-metallic [Sb@Rh12(CO)27]3? cluster has been known as for over three decades thanks to Vidal and co-workers, and represents the first example of an E-centered (E=heteroatom) icosahedral rhodium carbonyl cluster. However, its synthesis required high temperature (140–160 °C) and elevated CO pressure (400 atm). Applying the redox condensation method for cluster preparation, we herein report a new synthetic, high-yield route for preparing [Sb@Rh12(CO)27]3? under much milder conditions of temperature and pressure. Notably, when the same synthesis was carried out under N2 instead of CO atmosphere, the new isostructural but unsaturated derivative [Sb@Rh12(CO)24]4? was obtained, for which we report the full X-ray structural characterization. This species represents one of the few examples of an icosahedral cluster disobeying the electron-counting Wade-Mingos rules, possessing less than the expected 170 cluster valence electrons (CVEs). Judging from IR monitoring, the two species can be obtained one from the other by switching between N2 and CO atmosphere, making [Sb@Rh12(CO)27]3? a spontaneous CO-releasing molecule. Finally, the study of the chemical reactivity of [Sb@Rh12(CO)27]3? with PPh3 allowed us to obtain the new [{Sb@Rh12Sb(CO)25}2Rh(CO)2PPh3]7? dimeric compound, for which we herein report the full X-ray structural and 31P NMR analyses.     

Structure of the 30S translation initiation complex

Translation initiation, the rate-limiting step of the universal process of protein synthesis, proceeds through sequential, tightly regulated steps. In bacteria, the correct messenger RNA start site and the reading frame are selected when, with the help of initiation factors IF1, IF2 and IF3, the initiation codon is decoded in the peptidyl site of the 30S ribosomal subunit by the fMet-tRNA(fMet) anticodon. This yields a 30S initiation complex (30SIC) that is an intermediate in the formation of the 70S initiation complex (70SIC) that occurs on joining of the 50S ribosomal subunit to the 30SIC and release of the initiation factors. The localization of IF2 in the 30SIC has proved to be difficult so far using biochemical approaches, but could now be addressed using cryo-electron microscopy and advanced particle separation techniques on the basis of three-dimensional statistical analysis. Here we report the direct visualization of a 30SIC containing mRNA, fMet-tRNA(fMet) and initiation factors IF1 and GTP-bound IF2. We demonstrate that the fMet-tRNA(fMet) is held in a characteristic and precise position and conformation by two interactions that contribute to the formation of a stable complex: one involves the transfer RNA decoding stem which is buried in the 30S peptidyl site, and the other occurs between the carboxy-terminal domain of IF2 and the tRNA acceptor end. The structure provides insights into the mechanism of 70SIC assembly and rationalizes the rapid activation of GTP hydrolysis triggered on 30SIC-50S joining by showing that the GTP-binding domain of IF2 would directly face the GTPase-activated centre of the 50S subunit.     

Depression and antidepressants: molecular and cellular aspects

Clinical depression is viewed as a physical and psychic disease process having a neuropathological basis, although a clear understanding of its ethiopathology is still missing. The observation that depressive symptoms are influenced by pharmacological manipulation of monoamines led to the hypothesis that depression results from reduced availability or functional deficiency of monoaminergic transmitters in some cerebral regions. However, there are limitations to current monoamine theories related to mood disorders. Recently, a growing body of experimental data has showed that other classes of endogenous compounds, such as neuropeptides and amino acids, may play a significant role in the pathophysiology of affective disorders. With the development of neuroscience, neuronal networks and intracellular pathways have been identified and characterized, describing the existence of the interaction between monoamines and receptors in turn able to modulate the expression of intracellular proteins and neurotrophic factors, suggesting that depression/antidepressants may be intermingled with neurogenesis/neurodegenerative processes.     

RACK1 depletion in a mouse model causes lethality, pigmentation deficits and reduction in protein synthesis efficiency

The receptor for activated C-kinase 1 (RACK1) is a conserved structural protein of 40S ribosomes. Strikingly, deletion of RACK1 in yeast homolog Asc1 is not lethal. Mammalian RACK1 also interacts with many nonribosomal proteins, hinting at several extraribosomal functions. A knockout mouse for RACK1 has not previously been described. We produced the first RACK1 mutant mouse, in which both alleles of RACK1 gene are defective in RACK1 expression (ΔF/ΔF), in a pure C57 Black/6 background. In a sample of 287 pups, we observed no ΔF/ΔF mice (72 expected). Dissection and genotyping of embryos at various stages showed that lethality occurs at gastrulation. Heterozygotes (ΔF/+) have skin pigmentation defects with a white belly spot and hypopigmented tail and paws. ΔF/+ have a transient growth deficit (shown by measuring pup size at P11). The pigmentation deficit is partly reverted by p53 deletion, whereas the lethality is not. ΔF/+ livers have mild accumulation of inactive 80S ribosomal subunits by polysomal profile analysis. In ΔF/+ fibroblasts, protein synthesis response to extracellular and pharmacological stimuli is reduced. These results highlight the role of RACK1 as a ribosomal protein converging signaling to the translational apparatus.