Multilocus Bayesian Estimates of Intra-Oceanic Genetic Differentiation,Connectivity, and Admixture in Atlantic Swordfish (Xiphias gladius L.)

Previous genetic studies of Atlantic swordfish (Xiphias gladius L.) revealed significant differentiation among Mediterranean, North Atlantic and South Atlantic populations using both mitochondrial and nuclear DNA data. However, limitations in geographic sampling coverage, and the use of single loci, precluded an accurate placement of boundaries and of estimates of admixture. In this study, we present multilocus analyses of 26 single nucleotide polymorphisms (SNPs) within 10 nuclear genes to estimate population differentiation and admixture based on the characterization of 774 individuals representing North Atlantic, South Atlantic, and Mediterranean swordfish populations. Pairwise F _ST values, AMOVA, PCoA, and Bayesian individual assignments support the differentiation of swordfish inhabiting these three basins, but not the current placement of the boundaries that separate them. Specifically, the range of the South Atlantic population extends beyond 5°N management boundary to 20°N-25°N from 45°W. Likewise the Mediterranean population extends beyond the current management boundary at the Strait of Gibraltar to approximately 10°W. Further, admixture zones, characterized by asymmetric contributions of adjacent populations within samples, are confined to the Northeast Atlantic. While South Atlantic and Mediterranean migrants were identified within these Northeast Atlantic admixture zones no North Atlantic migrants were identified respectively in these two neighboring basins. Owing to both, the characterization of larger number of loci and a more ample spatial sampling coverage, it was possible to provide a finer resolution of the boundaries separating Atlantic swordfish populations than previous studies. Finally, the patterns of population structure and admixture are discussed in the light of the reproductive biology, the known patterns of dispersal, and oceanographic features that may act as barriers to gene flow to Atlantic swordfish.     

Direct antioxidant and protective effect of estradiol on isolated mitochondria

Estrogens have antioxidant properties which are due to their ability to bind to estrogen receptors and to up-regulate the expression of antioxidant enzymes via intracellular signalling pathways. Mitochondria are key organelles in the development of age-associated cellular damage. Recently, estrogen receptors were identified in mitochondria. The aim of this paper was to test whether estradiol directly affects mitochondria by preventing oxidative stress and protecting frail mitochondria. Incubation with estradiol at normal intracellular concentrations prevents the formation of reactive oxygen species by mitochondria in a saturable manner. Moreover, estradiol protects mitochondrial integrity as indicated by an increase in mitochondrial membrane potential. It also prevents the apoptogenic leakage of cytochrome c from mitochondria and as a result the mitochondrial content of this cytochrome c is maintained high. Thus, estradiol prevents the onset of the mitochondrial pathway of apoptosis by a direct effect on the organelle. Genistein, a phytoestrogen present at high concentration in soy, mimics the protective effect of estradiol by both decreasing the rate of formation of reactive oxygen species and preventing the release of cytochrome c from mitochondria.     

Mitochondrial DNA sequences are present inside nuclear DNA in rat tissues and increase with age

Mitochondrial DNA (mtDNA) mutations increase with age. However, the number of cells with predominantly mutated mtDNA is small in old animals. Here a new hypothesis is proposed: mtDNA fragments may insert into nuclear DNA contributing to aging and related diseases by alterations in the nucleus. Real-time PCR quantification shows that sequences of cytochrome oxidase III and 16S rRNA from mtDNA are present in highly purified nuclei from liver and brain in young and old rats. The sequences of these insertions revealed that they contain single nucleotide polymorphisms identical to those present in mtDNA of the same animal. Interestingly, the amount of mitochondrial sequences in nuclear DNA increases with age in both tissues. In situ hybridization of mtDNA to nuclear DNA confirms the presence of mtDNA sequences inside nuclear DNA in rat hepatocytes. Bone marrow metaphase cells from both young and old rats show mtDNA at centromeric regions in 20 out of the 2n = 40 chromosomes. Consequently, mitochondria can be a major trigger of aging but the final target could also be the nucleus.     

Age-related increase in xanthine oxidase activity in human plasma and rat tissues

This study assessed the role of xanthine oxidase in vascular ageing. A positive correlation between xanthine oxidase activity and age was found in human plasma. Similar results were found in rat plasma. Xanthine oxidase expression and activity in homogenates from the aortic wall were significantly higher in samples from old rats than in their young counterparts (p < 0.01). In rat skeletal muscle homogenates both xanthine oxidase expression and activity showed a similar age-related profile. Superoxide production by xanthine oxidase in aortic rings was higher in aged rats. Uric acid, the final product of xanthine oxidase has been proposed as a risk factor for coronary heart disease and an independent marker of worse prognosis in patients with moderate-to-severe chronic heart failure. These results give a possible explanation for this correlation and underscore the role of xanthine oxidase in ageing.     

Environmental monitoring of the biocontrol agent Pantoea agglomerans CPA‐2 applied to citrus fruit at preharvest

The aim of this study was to evaluate the environmental fate and behaviour of the biocontrol product based on Pantoea agglomerans CPA‐2 cells after its release into the field. Three different methods, dilution plating, quantitative real‐time PCR (qPCR) and propidium monoazide combined with qPCR (PMA‐qPCR) were used to track the CPA‐2 population. Populations quantified by qPCR were statistically different compared with those by the PMA‐qPCR and dilution plating methods. In addition, the spray dispersion of the CPA‐2 treatment was evaluated using water‐sensitive papers. A lack of dispersion of the CPA‐2 treatment was observed at distances of 2.5 ± 0.5 m. The presence and persistence of CPA‐2 in the environment were monitored in different areas, by dilution plating and confirmed by conventional PCR. The results showed that CPA‐2 can survive but not proliferate on weed and leaves. The persistence on inert surfaces, such as motorised backpack sprayer, gloves and working clothes, was less than 7 days. In conclusion, PMA‐qPCR was a potential tool for fast and specific monitoring of viable populations of CPA‐2 and it gave valuable information on population behaviour. Moreover, the results demonstrate that CPA‐2 would not present a risk for the environment because of its low establishment, survival and dispersion.     

Assessing the short‐term effects of capture,handling and tagging of sandgrouse

Capturing and marking free‐living birds permits the study of important aspects of their biology but may have undesirable effects. Bird welfare should be a primary concern, so it is necessary to evaluate and minimize any adverse effects of procedures used. We assess short‐term effects associated with the capture, handling and tagging with backpack‐mounted transmitters of Pin‐tailed Pterocles alchata and Black‐bellied Pterocles orientalis Sandgrouse, steppe birds of conservation concern. There was a significantly higher mortality (15%) during the first week after capture than during the following weeks (< 2.5%) in Pin‐tailed Sandgrouse, but no significant temporal mortality pattern in Black‐bellied Sandgrouse. In Pin‐tailed Sandgrouse, mortality rate during the first week increased with increasing relative transmitter and harness weight regardless of season, and with increasing handling time during the breeding season. There were no significant differences in mortality rate between study areas, type of tag, sex or age or an effect of restraint time. These results suggest the use of lighter transmitters (< 3% of the bird's weight) and a reduction of handling time (< 20 min), particularly during the breeding season, as essential improvements in procedure to reduce the mortality risk associated with the capture, handling and tagging of these vulnerable species.