CONVERGENT AND CORRELATED EVOLUTION OF MAJOR LIFE‐HISTORY TRAITS IN THE ANGIOSPERM GENUS LEUCADENDRON (PROTEACEAE)

Natural selection is expected to cause convergence of life histories among taxa as well as correlated evolution of different life‐history traits. Here, we quantify the extent of convergence of five key life‐history traits (adult fire survival, seed storage, degree of sexual dimorphism, pollination mode, and seed‐dispersal mode) and test hypotheses about their correlated evolution in the genus Leucadendron (Proteaceae) from the fire‐prone South African fynbos. We reconstructed a new molecular phylogeny of this highly diverse genus that involves more taxa and molecular markers than previously. This reconstruction identifies new clades that were not detected by previous molecular study and morphological classifications. Using this new phylogeny and robust methods that account for phylogenetic uncertainty, we show that the five life‐history traits studied were labile during the evolutionary history of the genus. This diversity allowed us to tackle major questions about the correlated evolution of life‐history strategies. We found that species with longer seed‐dispersal distances tended to evolve lower pollen‐dispersal distance, that insect‐pollinated species evolved decreased sexual dimorphism, and that species with a persistent soil seed‐bank evolved toward reduced fire‐survival ability of adults.     

Estimation of sex from the hyoid body in skeletal individuals from archeological sites

Recent forensic studies have shown that the hyoid bone is a sexually dimorphic element of the human skeleton. Given the advanced techniques of collecting human remains in archeological and forensic contexts, the recovery of hyoid bones is now more frequent in skeletal samples. For that reason the authors propose a new method for estimating sex based on hyoid bodies from archeological sites.     

Modelling parasite aggregation: disentangling statistical and ecological approaches

The overdispersion in macroparasite infection intensity among host populations is commonly simulated using a constant negative binomial aggregation parameter. We describe an alternative to utilising the negative binomial approach and demonstrate important disparities in intervention efficacy projections that can come about from opting for pattern-fitting models that are not process-explicit. We present model output in the context of the epidemiology and control of soil-transmitted helminths due to the significant public health burden imposed by these parasites, but our methods are applicable to other infections with demonstrable aggregation in parasite numbers among hosts.     

FlgN Is Required for Flagellum-Based Motility by Bacillus subtilis

The assembly of the bacterial flagellum is exquisitely controlled. Flagellar biosynthesis is underpinned by a specialized type III secretion system that allows export of proteins from the cytoplasm to the nascent structure. Bacillus subtilis regulates flagellar assembly using both conserved and species-specific mechanisms. Here, we show that YvyG is essential for flagellar filament assembly. We define YvyG as an orthologue of the Salmonella enterica serovar Typhimurium type III secretion system chaperone, FlgN, which is required for the export of the hook-filament junction proteins, FlgK and FlgL. Deletion of flgN (yvyG) results in a nonmotile phenotype that is attributable to a decrease in hag translation and a complete lack of filament polymerization. Analyses indicate that a flgK-flgL double mutant strain phenocopies deletion of flgN and that overexpression of flgK-flgL cannot complement the motility defect of a ΔflgN strain. Furthermore, in contrast to previous work suggesting that phosphorylation of FlgN alters its subcellular localization, we show that mutation of the identified tyrosine and arginine FlgN phosphorylation sites has no effect on motility. These data emphasize that flagellar biosynthesis is differentially regulated in B. subtilis from classically studied Gram-negative flagellar systems and questions the biological relevance of some posttranslational modifications identified by global proteomic approaches.     

Eutrophication impacts on a river macrophyte

The postulated relationship between eutrophication, enhanced standing macrophyte crop and flow impedance was assessed in 14 rivers across the UK. We sampled the July standing crop of Ranunculus subgenus Batrachium at 14 rivers across England and southern Scotland, at sites where there is a known relationship between standing crop and flow impedance. We relate standing crop to variation in carbon concentrations and to elevated phosphorus concentrations, using regression analysis. Standing crop increased significantly with P availability as soluble reactive phosphorus (filtered SRP) and total phosphorus (TP). Best subsets multiple regression analysis suggests that, based on this sample of sites, there is evidence that macrophyte biomass increases with SRP concentrations and also increases with the amount of carbon as HCO₃ for a given concentration of SRP in the water. Thus eutrophication is found to increase the standing crop of a submerged aquatic plant in UK rivers. Current targets for P reduction may not be sufficient and managers should now also recognise that eutrophication can exacerbate flood risk by elevating macrophyte standing crop.     

Increased oxidative stress in barn swallows from the Chernobyl region

The Chernobyl nuclear accident produced the largest unintended release of radionuclides in history, with dramatic consequences for humans and other organisms. Exposure to ionizing radiation is known to reduce circulating and stored levels of specific antioxidants in birds and humans, thus potentially increasing oxidative stress. However, overall effects of radioactive exposure on oxidative status have never been investigated in any free ranging vertebrate. We measured plasma antioxidant capacity and concentration of reactive oxygen metabolites in adult barn swallows (Hirundo rustica) from colonies with variable background radiation levels in the Chernobyl region in Ukraine and Belarus. We predicted that antioxidants would decrease while reactive oxygen metabolites would increase with exposure to increasing levels of radiation at the breeding sites. Consistent with this expectation, radiation level positively predicted plasma concentration of reactive oxygen metabolites, whereas no significant covariation was found with non-enzymatic plasma antioxidant capacity. An index of oxidative stress was also larger in barn swallows exposed to high contamination levels. Thus, radioactive contamination appeared to be responsible for the increased generation of reactive oxygen metabolites and the imbalance between reactive oxygen metabolites and non-enzymatic plasma antioxidant capacity.     

Detection of Brucella canis in a dog in Italy

Brucella spp. is a worldwide zoonotic pathogen. Infection by Brucella canis in dogs is endemic in the Southern USA and in Central and South America, but it appears sporadically in other parts of the world, including Europe. Tissue samples from a dog with chronic prostatitis, discospondylitis and locomotor problems were subjected to clinical and laboratory examinations. B. canis was detected by PCR in biological fluids and tissues of the animal, while antibodies to B. canis were found in the serum, providing additional strong evidence for the circulation of B. canis in Italy.     

Formation of methionine sulfoxide by peroxynitrite at position 1606 of von Willebrand factor inhibits its cleavage by ADAMTS-13: A new prothrombotic mechanism in diseases associated with oxidative stress

An enhanced formation of reactive oxygen species and peroxynitrite occurs in several clinical settings including diabetes, coronary artery disease, stroke, sepsis, and chronic inflammatory diseases. Peroxynitrite oxidizes methionine and tyrosine residues to methionine sulfoxide (MetSO) and 3-nitrotyrosine (NT), respectively. Notably, ADAMTS-13 cleaves von Willebrand factor (VWF) exclusively at the Tyr1605–Met1606 peptide bond in the A2 domain. We hypothesized that peroxynitrite could oxidize either or both of these amino acid residues, thus potentially affecting ADAMTS-13-mediated cleavage. We tested our hypothesis using synthetic peptide substrates based on: (1) VWF Asp1596–Ala1669 sequence (VWF74) and (2) VWF Asp1596–Ala1669 sequence containing nitrotyrosine (VWF74-NT) or methionine sulfoxide (VWF74-MetSO) at position 1605 or 1606, respectively. The peptides were treated with recombinant ADAMTS-13 and the cleavage products analyzed by RP-HPLC. VWF74 oxidized by peroxynitrite underwent a severe impairment of its hydrolysis. Likewise, VWF74-MetSO was minimally hydrolyzed, whereas VWF74-NT was hydrolyzed slightly more efficiently than VWF74. Oxidation by peroxynitrite of purified VWF multimers inhibited ADAMTS-13 hydrolysis, but did not alter their electrophoretic pattern nor their ability to induce platelet agglutination by ristocetin. Moreover, VWF purified from type 2 diabetic patients showed oxidative damage, as revealed by enhanced carbonyl, NT, and MetSO content and was partially resistant to ADAMTS-13 hydrolysis. In conclusion, peroxynitrite may contribute to prothrombotic effects, hindering the proteolytic processing by ADAMTS-13 of high-molecular-weight VWF multimers, which have the highest ability to bind and activate platelets in the microcirculation.     

PKC delta and NADPH oxidase in retinoic acid-induced neuroblastoma cell differentiation

The role of reactive oxygen species (ROS) in the regulation of signal transduction processes has been well established in many cell types and recently the fine tuning of redox signalling in neurons received increasing attention. With regard to this, the involvement of NADPH oxidase (NOX) in neuronal pathophysiology has been proposed but deserves more investigation. In the present study, we used SH-SY5Y neuroblastoma cells to analyse the role of NADPH oxidase in retinoic acid (RA)-induced differentiation, pointing out the involvement of protein kinase C (PKC) delta in the activation of NOX. Retinoic acid induces neuronal differentiation as revealed by the increased expression of MAP2, the decreased cell doubling rate, and the gain in neuronal morphological features and these events are accompanied by the increased expression level of PKC delta and p67^phox, one of the components of NADPH oxidase. Using DPI to inhibit NOX activity we show that retinoic acid acts through this enzyme to induce morphological changes linked to the differentiation. Moreover, using rottlerin to inhibit PKC delta or transfection experiments to overexpress it, we show that retinoic acid acts through this enzyme to induce MAP2 expression and to increase p67^phox membrane translocation leading to NADPH oxidase activation. These findings identify the activation of PKC delta and NADPH oxidase as crucial steps in RA-induced neuroblastoma cell differentiation.