Tobacco smoking is a risk factor for numerous disorders, including cancers affecting organs outside the respiratory tract. Epidemiological data suggest that smoking is a greater risk factor for these cancers in males compared to females. This observation, together with the fact that males have a higher incidence of, and mortality from, most non-sex-specific cancers, remain unexplained. Loss of chromosome Y (LOY) in blood cells is associated with increased risk of non-hematological tumors. We demonstrate here that smoking is associated with LOY in blood cells in three independent cohorts (TwinGene: odds ratio [OR]=4.3, 95% CI =2.8-6.7; ULSAM: OR=2.4, 95% CI=1.6-3.6; and PIVUS: OR=3.5, 95% CI=1.4-8.4) encompassing a total of 6014 men. The data also suggest that smoking has a transient and dose-dependent mutagenic effect on LOY-status. The finding that smoking induces LOY thus links a preventable risk factor with the most common acquired human mutation.
Question: We studied the patterns of plant species co‐occurrence on three, nested, spatial scales in semi‐natural grassland communities and explored the possible ecological processes underlying the patterns. Location: Dry, semi‐natural grasslands in a 4.5 km x 4.5 km area on the Baltic Island of Oland (Sweden). Methods: The study used replicated samples on three, nested, spatial scales: 50 cm x 50 cm plots (N= 516), grassland patches (N = 109) and the whole landscape (N= 6). We used a null model approach to study species co‐occurrence patterns and compared the ecological amplitudes of the pairs of species contributing most to the patterns. We used linear models to search for associations between species segregation and environmental and landscape factors. Results and Conclusions: Our results support the prediction that patterns of species co‐occurrence are likely to be influenced by different mechanisms on different spatial scales. On the plot scale, we interpreted the species segregation in terms of species interactions. The degree of species segregation was significantly associated with the plots'positions within the grassland patches (edge effects) and with management intensity of the grasslands ‐ both variables can be assumed to influence species interactions. On the grassland patch scale, we interpreted the species segregation in terms of within‐patch environmental heterogeneity. The degree of segregation was significantly associated with the area of the grassland patches and with management intensity ‐ both variables that are likely to be related to environmental heterogeneity within the grasslands. Species segregation on the landscape scale was interpreted in terms of environmental heterogeneity among grassland patches and was significantly associated with land‐use history.
1600-0706.2002.11907.x General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Within-population gene diversity (H S ) was estimated (using allozyme markers) for 16 populations of the perennial, outcrossing plant, Gypsophila fastigiata, on the Baltic island of O 8 land. The populations were characterized by data on extent, density, life-stages, and habitat diversity. Populations were classed as central or peripheral in relation to the distribution of ''alvar'' (habitats with shallow, calcareous soils on limestone bedrock) on southern O 8 land. Three minimal adequate models were used to explain H S and the proportions of juveniles and dead adults. In the first model, H S was significantly lower in peripheral populations and there were no significant additional effects of other explanatory variables. The lower diversity in peripheral populations can be explained by a combination of genetic drift (in populations that vary in size in response to habitat fragmentation) and lower levels of interpopulation gene flow than in central populations. In the two life-stage models, peripheral populations had significantly larger proportions of both juveniles and dead adultsindicating a greater demographic turnover than in the central populations. There were also significant effects of H S and species diversity on the proportion of juveniles. The central or peripheral position of populations is the strongest predictor of both within-population gene diversity and life-stage dynamics in O 8 land G. fastigiata. M. Lönn, Södertörn Uni6. College,
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