Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean

Increasing tropospheric ozone levels over the past 150 years have led to a significant climate perturbation; the prediction of future trends in tropospheric ozone will require a full understanding of both its precursor emissions and its destruction processes. A large proportion of tropospheric ozone loss occurs in the tropical marine boundary layer and is thought to be driven primarily by high ozone photolysis rates in the presence of high concentrations of water vapour. A further reduction in the tropospheric ozone burden through bromine and iodine emitted from open-ocean marine sources has been postulated by numerical models, but thus far has not been verified by observations. Here we report eight months of spectroscopic measurements at the Cape Verde Observatory indicative of the ubiquitous daytime presence of bromine monoxide and iodine monoxide in the tropical marine boundary layer. A year-round data set of co-located in situ surface trace gas measurements made in conjunction with low-level aircraft observations shows that the mean daily observed ozone loss is approximately 50 per cent greater than that simulated by a global chemistry model using a classical photochemistry scheme that excludes halogen chemistry. We perform box model calculations that indicate that the observed halogen concentrations induce the extra ozone loss required for the models to match observations. Our results show that halogen chemistry has a significant and extensive influence on photochemical ozone loss in the tropical Atlantic Ocean boundary layer. The omission of halogen sources and their chemistry in atmospheric models may lead to significant errors in calculations of global ozone budgets, tropospheric oxidizing capacity and methane oxidation rates, both historically and in the future.     

Autoradiography and differential hemoglobin staining as aids to the study of fish hematology

Summary The confused state of the existing knowledge regarding the cell types in peripheral blood and hematopoiesis of fishes has been highlighted. Inadequacies of techniques presently used have been pointed out and the advantages of using Graham-Knoll's method for haemoglobin staining when counter stained with Giemsa together with autoradiography using tritiated thymidine have been demonstrated.Thanks are due to the University of Rajasthan for working facilities. J.S.D. is grateful to University Grants Commission, New Delhi for grant of Research Fellowship during the tenure of which this work was done.     

Large-scale association analyses identify new loci influencing glycemic traits and provide insight into the underlying biological pathways

Through genome-wide association meta-analyses of up to 133,010 individuals of European ancestry without diabetes, including individuals newly genotyped using the Metabochip, we have increased the number of confirmed loci influencing glycemic traits to 53, of which 33 also increase type 2 diabetes risk (q < 0.05). Loci influencing fasting insulin concentration showed association with lipid levels and fat distribution, suggesting impact on insulin resistance. Gene-based analyses identified further biologically plausible loci, suggesting that additional loci beyond those reaching genome-wide significance are likely to represent real associations. This conclusion is supported by an excess of directionally consistent and nominally significant signals between discovery and follow-up studies. Functional analysis of these newly discovered loci will further improve our understanding of glycemic control.     

Excess bioavailability of zinc may cause obesity in humans

The body weight or body weight/height ratio exhibits a positive linear correlation to hair zinc (Zn) concentration which is more strongly positive in men than in women. The obese of both sexes possess higher Zn concentrations in their hair than those with normal body weight/height. The degree of obesity increases with the increase in the hair Zn concentration.     

The chemistry and biology of inhibitors and pro-drugs targeted to glutathione S-transferases

The cytosolic glutathione S-transferases are a family of structurally homologous enzymes with multiple functions, including xenobiotic detoxification, clearance of oxidative stress products, and modulation of cell proliferation and apoptosis signaling pathways. This wideranging functional repertoire leads to several possible therapeutic uses for isoform-specific GST inhibitors. These inhibitors may be used, in principle, to modulate tumor cell drug resistance, as sensitizers to therapeutically directed oxidative stress, to enhance cell proliferation and to augment anti-malarial drugs. With increasing knowledge of GST structural and function, rational design strategies and mechanism-based inhibitors have been exploited successfully. However, design of isoform specificity remains a significant challenge in GST inhibitor development. Strategies for further inhibitor design and their possible limitations, along with potential therapeutic uses, are summarized.Received 24 November 2004; received after revision 12 January 2005; accepted 11 February 2005     

Autoradiography and differential hemoglobin staining as aids to the study of fish hematology.

The confused state of the existing knowledge regarding the cell types in peripheral blood and hematopoiesis of fishes has been highlighted. Inadequacies of techniques presently used have been pointed out and the advantages of using Graham-Knoll's method for haemoglobin staining when counter stained with Giemsa together with autoradiography using tritiated thymidine have been demonstrated.