71 research outputs found

    A year-round study on digestive enzymes in the Arctic copepod Calanus glacialis: implications for its capability to adjust to changing environmental conditions

    Get PDF
    The biomass of zooplankton communities in Arctic shelf regions is dominated by the calanoid copepod Calanus glacialis . This species spends the winter in deep water, and then, metabolic rates are low. In late winter, it migrates to the surface where the spring generation develops. To date, it is not fully understood what regulates the activity of the copepods and how it coincides with food availability. To fill this gap, we sampled C. glacialis, mainly copepodite stage V, in a high-Arctic fjord in monthly intervals for 1 year and determined proteinase and lipase/esterase activities in relation to food availability and depth distribution of the copepods. By substrate SDSPAGE(sodium dodecyl sulfate-polyacrylamide gel electrophoresis),we tackled changes in specific isoforms. We found a clear seasonal enzyme activity pattern. Activities in winter were reduced by at least 75 % as compared to spring. Substrate SDS-PAGE showed high heterogeneity of lipolytic enzymes, which could reflect extensive accumulation and metabolization of internal lipids. Only one band of proteolytic activity was found, and it intensified with the onset of the algal blooms. In late winter/spring, we sampled females and CIV, which also showed high digestive enzyme activities in surface water and low activities in deep water. High enzyme activities were related to the ice algal and phytoplankton blooms in spring. In autumn, the copepods descended although food was still available. C. glacialis could thus benefit from an early ice breakup and early algal blooms, but not from long-lasting phytoplankton availabilit

    New ecosystems in the deep subsurface follow the flow of water driven by geological activity

    Get PDF
    Eukarya have been discovered in the deep subsurface at several locations in South Africa, but how organisms reach the subsurface remains unknown. We studied river-subsurface fissure water systems and identified Eukarya from a river that are genetically identical for 18S rDNA. To further confirm that these are identical species one metazoan species recovered from the overlying river interbred successfully with specimen recovered from an underlying mine at −1.4 km. In situ seismic simulation experiments were carried out and show seismic activity to be a major force increasing the hydraulic conductivity in faults allowing organisms to create ecosystems in the deep subsurface. As seismic activity is a non-selective force we recovered specimen of algae and Insecta that defy any obvious other explanation at a depth of −3.4 km. Our results show there is a steady flow of surface organisms to the deep subsurface where some survive and adapt and others perish. As seismic activity is also present on other planets and moons in our solar system the mechanism elucidated here may be relevant for future search and selection of landing sites in planetary exploration.publishedVersio

    Violent aggression predicted by multiple pre-adult environmental hits

    Get PDF
    Early exposure to negative environmental impact shapes individual behavior and potentially contributes to any mental disease. We reported previously that accumulated environmental risk markedly decreases age at schizophrenia onset. Follow-up of matched extreme group individuals (≤1 vs. ≥3 risks) unexpectedly revealed that high-risk subjects had >5 times greater probability of forensic hospitalization. In line with longstanding sociological theories, we hypothesized that risk accumulation before adulthood induces violent aggression and criminal conduct, independent of mental illness. We determined in 6 independent cohorts (4 schizophrenia and 2 general population samples) pre-adult risk exposure, comprising urbanicity, migration, physical and sexual abuse as primary, and cannabis or alcohol as secondary hits. All single hits by themselves were marginally associated with higher violent aggression. Most strikingly, however, their accumulation strongly predicted violent aggression (odds ratio 10.5). An epigenome-wide association scan to detect differential methylation of blood-derived DNA of selected extreme group individuals yielded overall negative results. Conversely, determination in peripheral blood mononuclear cells of histone-deacetylase1 mRNA as ‘umbrella mediator’ of epigenetic processes revealed an increase in the high-risk group, suggesting lasting epigenetic alterations. Together, we provide sound evidence of a disease-independent unfortunate relationship between well-defined pre-adult environmental hits and violent aggression, calling for more efficient prevention

    Theia: Faint objects in motion or the new astrometry frontier

    Get PDF

    Measuring the predictability of life outcomes with a scientific mass collaboration.

    Get PDF
    How predictable are life trajectories? We investigated this question with a scientific mass collaboration using the common task method; 160 teams built predictive models for six life outcomes using data from the Fragile Families and Child Wellbeing Study, a high-quality birth cohort study. Despite using a rich dataset and applying machine-learning methods optimized for prediction, the best predictions were not very accurate and were only slightly better than those from a simple benchmark model. Within each outcome, prediction error was strongly associated with the family being predicted and weakly associated with the technique used to generate the prediction. Overall, these results suggest practical limits to the predictability of life outcomes in some settings and illustrate the value of mass collaborations in the social sciences

    Polygenic prediction of educational attainment within and between families from genome-wide association analyses in 3 million individuals

    Get PDF
    We conduct a genome-wide association study (GWAS) of educational attainment (EA) in a sample of ~3 million individuals and identify 3,952 approximately uncorrelated genome-wide-significant single-nucleotide polymorphisms (SNPs). A genome-wide polygenic predictor, or polygenic index (PGI), explains 12-16% of EA variance and contributes to risk prediction for ten diseases. Direct effects (i.e., controlling for parental PGIs) explain roughly half the PGI's magnitude of association with EA and other phenotypes. The correlation between mate-pair PGIs is far too large to be consistent with phenotypic assortment alone, implying additional assortment on PGI-associated factors. In an additional GWAS of dominance deviations from the additive model, we identify no genome-wide-significant SNPs, and a separate X-chromosome additive GWAS identifies 57
    • …
    corecore