Physiological thiols as promoters of glutathione oxidation and modifying agents in protein S-thiolation.

Glutathione is one of the most relevant antioxidants present in cells. It exerts its scavenging action through the involvement of efficient and ubiquitous enzymes. GSH on the other hand, because of its chemical features, can scavenge reactive oxygen species without the involvement of enzymatic systems. The study deals with the mobilization of GSH pool in a nonenzymatic antioxidant system by other physiological thiols (i.e., cysteine and cysteinyl-glycine), which are far more sensitive than GSH to oxidative conditions. These thiol compounds, in the presence of iron/EDTA, can promote oxygen activation through their oxidation to disulfides. GSH, through trans-thiolation reactions, can regenerate Cys and CysGly, which can then recycle, thus inducing a massive GSH oxidation. In these conditions, making use of bovine lens aldose reductase as a protein model, evidence is given that Cys and CysGly promote specific protein S-thiolation reactions. The possibility that GSH may be recruited in controlling cellular oxygen tension is considered.     

Vegetation of tuscan ultramafic soils in relation to edaphic and physical factors

Vegetation and soil sampling were carried out in 80 plots located in five different ultramafic (serpentine) sites of Tuscany, central Italy. The physical and chemical features of each plot were determined and the species composition and cover recorded. The exchangeable fraction of soil metals was analysed because it gives a measure of their concentrations available to plants. The plots were classified by cluster analysis and ANOVA was used to compare the environmental variables of the groups of plots. Canonical correspondence analysis was used to detect the principal factors for gradients of species composition within the plant communities. A higher content of exchangeable metals was found under the more evolved and structured plant communities, suggesting that serpentine vegetation of Tuscany is not strongly limited by soil metals, such as chromium, cobalt, nickel and magnesium, typically associated with ultramafic soils. The low nutrient content of the soils and drought stress mainly due to topographical features, appear to have a more significant role in determining the typical scattered vegetation of the Tuscan ultramafics.     

Pneumococcal pili are composed of protofilaments exposing adhesive clusters of Rrg A

Pili have been identified on the cell surface of Streptococcus pneumoniae, a major cause of morbidity and mortality worldwide. In contrast to Gram-negative bacteria, little is known about the structure of native pili in Gram-positive species and their role in pathogenicity. Triple immunoelectron microscopy of the elongated structure showed that purified pili contained RrgB as the major compound, followed by clustered RrgA and individual RrgC molecules on the pilus surface. The arrangement of gold particles displayed a uniform distribution of anti-RrgB antibodies along the whole pilus, forming a backbone structure. Antibodies against RrgA were found along the filament as particulate aggregates of 2-3 units, often co-localised with single RrgC subunits. Structural analysis using cryo electron microscopy and data obtained from freeze drying/metal shadowing technique showed that pili are oligomeric appendages formed by at least two protofilaments arranged in a coiled-coil, compact superstructure of various diameters. Using extracellular matrix proteins in an enzyme-linked immunosorbent assay, ancillary RrgA was identified as the major adhesin of the pilus. Combining the structural and functional data, a model emerges where the pilus RrgB backbone serves as a carrier for surface located adhesive clusters of RrgA that facilitates the interaction with the host.     

Genetic relationships and clonal identity in a collection of commercially relevant poplar cultivars assessed by AFLP and SSR

A collection of 66 poplar commercial clones widely cultivated in Italy, China and in other countries of southern Europe and belonging to various poplar species and hybrids, have been fingerprinted using both amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR) techniques. Three AFLP primer combinations and six SSRs unambiguously genotyped the analysed poplar collection, with the exception of three groups of six, four and two individuals, which turned out to be indistinguishable even if they met the standards currently applied for distinctness, uniformity and stability (DUS) testing when registered. High levels of variation were detected with both molecular techniques; a total of 201 AFLP bands were amplified of which 96% turned out to be polymorphic and up to 15 SSR alleles were identified at a single locus, with a mean of 9.3 alleles per locus in the case of Populus × canadensis. The probability of matching fortuitously any two genotypes at all the SSR loci in the case of P. × canadensis was less then 7.5×10^–9. The AFLP-derived dendrogram and principal coordinate analysis (PCOORDA) clustered the clones with respect to their taxonomic classification, and allowed their genetic interrelationships to be established. Correct identification of poplar varieties is essential for ensuring the effective correspondence between the real and the declared identity of a clone, to avoid commercial frauds, and to establish breeding programmes. Molecular markers may play a major role to satisfy all these needs.     

Strong genetic isolation despite wide distribution in a commercially exploited coastal shark

The common smoothhound, Mustelus mustelus, is an epibenthic species targeted by fisheries around the world driven by the increasing demand for shark products. Given the wide-spread occurrence of this species and corresponding lack of molecular data in many areas of said distribution, baseline molecular assessments of this commercially important shark may contribute to finer-scale analyses in areas in which this species is targeted. Therefore, population genetic analyses were conducted along the East Atlantic, from the Mediterranean Sea to the south-east coast of Africa, using microsatellite markers and the mitochondrial control region (mtCR). Overall, M. mustelus displayed low to moderate genetic diversity, with the Mediterranean populations appearing to exhibit the lowest mitochondrial diversity, and the west African populations displaying the lowest nuclear diversity. Microsatellite analysis indicated strong genetic differentiation between the three regions, with finer-scale population structure in each region, without correlation between genetic and geographical distance. For the mtCR sequences, a total of 18 haplotypes were identified, with a high degree of divergence discernable between the regions, largely in accordance with the microsatellite data. The study documents a remarkable level of population isolation across a vast area, suggesting little or no present-day connectivity among extant populations. The findings may serve as an essential baseline for global population management and commercial traceability of this threatened shark.