Changes in cardiac troponins with gestational age explain changes in cardiac muscle contractility in the sheep fetus

The development of the adult cardiac troponin complex in conjunction with changes in cardiac function and cardiomyocyte binucleation has not been systematically characterized during fetal life in a species where maturation of the cardiomyocytes occurs prenatally as it does in the human. The aim of this study was to correlate the expression of each of the major adult troponin isoforms (T, I, and C) during late gestation (term of 150 days) to changes in both Ca(2+) sensitivity and maximum Ca(2+)-activated force of the contractile apparatus and the maturation of cardiomyocytes. The percentage of mononucleated cardiomyocytes in the right ventricle decreased with gestational age to 46% by 137-142 days of gestation. The length of binucleated cardiomyocytes did not change with gestational age, but the length of binucleated cardiomyocytes relative to heart weight decreased with gestational age. There was no change in the expression of adult cardiac troponin T with increasing gestation. The contractile apparatus was significantly more sensitive to Ca(2+) at 90 days compared with either 132 or 139 days of gestation, consistent with an ～30% increase in the expression of adult cardiac troponin I between 90 and 110 days of gestation. Maximum Ca(2+)-activated force significantly increased from 90 days compared with 130 days consistent with an increase of ～40% in cardiac troponin C protein expression. These data show that increased adult cardiac troponin I and C protein expression across late gestation is consistent with reduced Ca(2+) sensitivity and increased maximum Ca(2+)-activated force. Furthermore, changes in cardiac troponin C, not I, protein expression track with the timing of cardiomyocyte binucleation.     

Ecosystem controls on nitrogen fixation in boreal feather moss communities

N fixation in feather moss carpets is maximized in late secondary successional boreal forests; however, there is limited understanding of the ecosystem factors that drive cyanobacterial N fixation in feather mosses with successional stage. We conducted a reciprocal transplant experiment to assess factors in both early and late succession that control N fixation in feather moss carpets dominated by Pleurozium schreberi. In 2003, intact microplots of moss carpets (30 cm × 30 cm × 10–20 cm deep) were excavated from three early secondary successional (41–101 years since last fire) forest sites and either replanted within the same stand or transplanted into one of three late successional (241–356 years since last fire) forest sites and the transverse was done for late successional layers of moss. Moss plots were monitored for changes in N-fixation rates by acetylene reduction (June 2003–September 2005) and changes in the presence of cyanobacteria on moss shoots by microscopy (2004). Forest nutrient status was measured using ionic resin capsules buried in the humus layer. Late successional forests exhibit high rates of N fixation and consistently high numbers of cyanobacteria on moss shoots, but low levels of available N. Conversely, early successional forests have higher N availability and have low rates of N fixation and limited presence of cyanobacteria on moss shoots. Transplantation of moss carpets resulted in a significant shift in presence and activity of cyanobacteria 1 year after initiation of the experiment responding to N fertility differences in early versus late successional forests.     

Protective effect of magnesium and potassium ions on the permeability of the external mitochondrial membrane

The data reported are fully consistent with the well-known observation that exogenous cytochrome c (cyto-c) molecules do not permeate through the outer membrane of mitochondria (MOM) incubated in isotonic medium (250 mM sucrose). Cyto-c is unable to accept electrons from the sulfite/cyto-c oxido-reductase (Sox) present in the intermembrane space, unless mitochondria are solubilized. Mitochondria incubated in a very high hypotonic medium (25 mM sucrose), in contrast to any expectation, continue to be not permeable to added cyto-c even if Sox and adenylate kinase are released into the medium. The succinate/exogenous cyto-c reductase activity, very low in isotonic medium, is greatly increased decreasing the osmolarity of the medium but in both cases remains insensitive to proteolysis by added trypsin. In hypotonic medium, magnesium and potassium ions have a protective effect on the release of enzymes and on the reactivity of cyto-c as electron acceptor from both sulfite and succinate; results which are consistent with the view that MOM preserves its identity and remains not permeable to exogenous cyto-c. This report strengthens the proposal, supported by previously published data that in isotonic medium the exogenous NADH/cyto-c electron transport system is catalyzed by intact mitochondria, not permeable to added cyto-c.     

Biogeography and adaptation of Notothenioid fish: hemoglobin function and globin-gene evolution

The recognition of the important role of the polar habitats in global climate changes has awakened great interest in the evolutionary biology of polar organisms. They are exposed to strong environmental constraints, and it is important to understand how they have adapted to cope with these challenges and to what extent adaptations may be upset by current climate changes. We present an introductory overview of the evolution of the Antarctic fish fauna with emphasis on the dominant perciform sub-order Notothenioidei, as well as some specific comments on the biogeography of the three phyletically basal notothenioid families. The wealth of information on the ecology and biodiversity of the species inhabiting high-Antarctic and sub-Antarctic regions provides a necessary framework for better understanding the origin, evolution and adaptation of this unique group of fish. Notothenioidei offer opportunities for identification of the biochemical characters or the physiological traits responsible for thermal adaptation. The availability of phylogenetically related taxa in a wide range of latitudes has allowed to look into the molecular bases of environmentally driven phenotypic gain and loss of function. In the process of cold adaptation, the evolutionary trend of notothenioids has produced unique specialisations, including modification of hematological characteristics, e.g. decreased amounts and multiplicity of hemoglobins. The Antarctic family Channichthyidae (the notothenioid crown group) is devoid of hemoglobin. This loss is related to a single deletional event removing all globin genes with the exception of the inactive 3' end of adult alpha-globin. In reviewing hemoglobin structure, function and phylogeny, the evolution of the fish Root effect is analysed in detail. Adaptation of the oxygen-transport system in notothenioids seems to be based on evolutionary changes involving levels of biological organisation higher than the structure of hemoglobin.     

The N-Terminal Domain of cGAS Determines Preferential Association with Centromeric DNA and Innate Immune Activation in the Nucleus

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Serum α-tocopherol and γ-tocopherol concentrations and prostate cancer risk in the PLCO Screening Trial: a nested case-control study

Background

Vitamin E compounds exhibit prostate cancer preventive properties experimentally, but serologic investigations of tocopherols, and randomized controlled trials of supplementation in particular, have been inconsistent. Many studies suggest protective effects among smokers and for aggressive prostate cancer, however.

Methods

We conducted a nested case-control study of serum α-tocopherol and γ-tocopherol and prostate cancer risk in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, with 680 prostate cancer cases and 824 frequency-matched controls. Multivariate-adjusted, conditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for tocopherol quintiles.

Results

Serum α-tocopherol and γ-tocopherol were inversely correlated (r = −0.24, p<0.0001). Higher serum α-tocopherol was associated with significantly lower prostate cancer risk (OR for the highest vs. lowest quintile = 0.63, 95% CI 0.44–0.92, p-trend 0.05). By contrast, risk was non-significantly elevated among men with higher γ-tocopherol concentrations (OR for the highest vs. lowest quintile = 1.35, 95% CI 0.92–1.97, p-trend 0.41). The inverse association between prostate cancer and α-tocopherol was restricted to current and recently former smokers, but was only slightly stronger for aggressive disease. By contrast, the increased risk for higher γ-tocopherol was more pronounced for less aggressive cancers.

Conclusions

Our findings indicate higher α-tocopherol status is associated with decreased risk of developing prostate cancer, particularly among smokers. Although two recent controlled trials did not substantiate an earlier finding of lower prostate cancer incidence and mortality in response to supplementation with a relatively low dose of α-tocopherol, higher α-tocopherol status may be beneficial with respect to prostate cancer risk among smokers. Determining what stage of prostate cancer development is impacted by vitamin E, the underlying mechanisms, and how smoking modifies the association, is needed for a more complete understanding of the vitamin E-prostate cancer relation.