997 resultados para Jörgensen
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chapters 3-4
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Signatur des Originals: S 36/F04823
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Published in parts.
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Dissertação para obtenção do Grau de Mestre em Bioorgânica
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Tese de Doutoramento em Ciência Política e Relações Internacionais
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The specific composition and abundance variation of the ciliate community from a wastewater discharge zone in the Bahía Blanca estuary, Argentina, were studied all throughout a year, from June 1995 to May 1996. The polluted area exhibited high values of particulate organic matter and nutrients, particularly phosphates. Aloricate ciliates were represented by 15 species belonging to the genera Strombidium Claparède & Lachmann, 1859; Strombidinopsis Kent, 1881; Cyrtostrombidium Lynn & Gilron, 1993; Strobilidium Schewiakoff, 1983; Lohmmanniella Leegaard, 1915 and Tontonia Fauré-Fremiet, 1914. Tintinnids were represented by nine species belonging to the genera Tintinnidium Kent, 1881, Tintinnopsis Stein, 1867 and Codonellopsis Jörgensen, 1924. The total abundance of aloricate ciliates reached a peak of 1,800 ind. 1-1 and the total abundance of tintinnids reached a peak of 9,400 ind. 1-1. Tintinnidium balechi Barría de Cao, 1981 was the most abundant ciliate in the community. Considerations on the presence and abundance of ciliates are made in relation to physicochemical and biochemical parameters.
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Waist-hip ratio (WHR) is a measure of body fat distribution and a predictor of metabolic consequences independent of overall adiposity. WHR is heritable, but few genetic variants influencing this trait have been identified. We conducted a meta-analysis of 32 genome-wide association studies for WHR adjusted for body mass index (comprising up to 77,167 participants), following up 16 loci in an additional 29 studies (comprising up to 113,636 subjects). We identified 13 new loci in or near RSPO3, VEGFA, TBX15-WARS2, NFE2L3, GRB14, DNM3-PIGC, ITPR2-SSPN, LY86, HOXC13, ADAMTS9, ZNRF3-KREMEN1, NISCH-STAB1 and CPEB4 (P = 1.9 × 10⁻⁹ to P = 1.8 × 10⁻⁴⁰) and the known signal at LYPLAL1. Seven of these loci exhibited marked sexual dimorphism, all with a stronger effect on WHR in women than men (P for sex difference = 1.9 × 10⁻³ to P = 1.2 × 10⁻&supl;³). These findings provide evidence for multiple loci that modulate body fat distribution independent of overall adiposity and reveal strong gene-by-sex interactions.
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Circulating levels of adiponectin, a hormone produced predominantly by adipocytes, are highly heritable and are inversely associated with type 2 diabetes mellitus (T2D) and other metabolic traits. We conducted a meta-analysis of genome-wide association studies in 39,883 individuals of European ancestry to identify genes associated with metabolic disease. We identified 8 novel loci associated with adiponectin levels and confirmed 2 previously reported loci (P = 4.5×10(-8)-1.2×10(-43)). Using a novel method to combine data across ethnicities (N = 4,232 African Americans, N = 1,776 Asians, and N = 29,347 Europeans), we identified two additional novel loci. Expression analyses of 436 human adipocyte samples revealed that mRNA levels of 18 genes at candidate regions were associated with adiponectin concentrations after accounting for multiple testing (p<3×10(-4)). We next developed a multi-SNP genotypic risk score to test the association of adiponectin decreasing risk alleles on metabolic traits and diseases using consortia-level meta-analytic data. This risk score was associated with increased risk of T2D (p = 4.3×10(-3), n = 22,044), increased triglycerides (p = 2.6×10(-14), n = 93,440), increased waist-to-hip ratio (p = 1.8×10(-5), n = 77,167), increased glucose two hours post oral glucose tolerance testing (p = 4.4×10(-3), n = 15,234), increased fasting insulin (p = 0.015, n = 48,238), but with lower in HDL-cholesterol concentrations (p = 4.5×10(-13), n = 96,748) and decreased BMI (p = 1.4×10(-4), n = 121,335). These findings identify novel genetic determinants of adiponectin levels, which, taken together, influence risk of T2D and markers of insulin resistance.
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This report describes the partial purification and the characteristics of (Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) from an amphibian source. Toad kidney microsomes were solubilized with sodium deoxycholate and further purified by sodium dodecyl sulphate treatment and sucrose gradient centrifugation, according to the methods described by Lane et al. [(1973) J. Biol. Chem. 248, 7197--7200], Jørgensen [(1974) Biochim. Biophys. Acta 356, 36--52] and Hayashi et al. [(1977) Biochim. Biophys. Acta 482, 185--196]. (Na+ + K+)-ATPase preparations with specific activities up to 1000 mumol Pi/mg protein per h were obtained. Mg2+-ATPase only accounted for about 2% of the total ATPase activity. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed three major protein bands with molecular weights of 116 000, 62 000 and 26 000. The 116 000 dalton protein was phosphorylated by [gamma-32P]ATP in the presence of sodium but not in the presence of potassium. The 62 000 dalton component stained for glycoproteins. The Km for ATP was 0.40 mM, for Na+ 12.29 mM and for K+ 1.14 mM. The Ki for ouabain was 35 micron. Temperature activation curves showed two activity peaks at 37 degrees C and at 50 degrees C. The break in the Arrhenius plot of activity versus temperature appeared at 15 degrees C.
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African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations.
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The D2-protein is a high molecular weight protein involved in interneuronal adhesion. The concentration of D2-protein was measured both in aggregates of fetal rat telencephalic cells cultured in a chemically defined medium and in developing forebrain. Both the concentration of the D2-protein and the degree of sialylation were changed in the cultures in parallel with the corresponding values obtained from postnatal forebrain. In the cultures the highest specific concentration of D2-protein was observed after 12 days in culture. This value was 2.7 times higher than the average value of adult rat forebrain. Antibodies to D2-protein have previously been shown to inhibit fasciculation of neuritic fibers extending from cultured explants of sympathetic ganglia. We investigated the effect of such antibodies on the differentiation of aggregating telencephalic cells. By adding surplus antibodies to the cultures from day 11 to day 16 we were able to decrease the specific concentration of D2-protein on the neurons by 53% measured at day 19. The decrease was not compensated fully even after further 10 days in the culture. Although the concentration of D2-protein was decreased during the period of synaptogenesis no change was found in the specific concentration of a marker of mature synapses, the D3-protein. Thus, in this culture system synaptogenesis could proceed to an unimpaired extent in the presence of a decreased concentration of a putatively involved adhesion molecule. However, the specific concentration of two markers of myelination, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin basic protein, were both increased, suggesting an antibody-induced stimulation of myelination in the cultured aggregates.
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Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries-induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life-history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries.
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Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to "shifting" reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in "true" reference points, whereas the latter is caused by changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and "precautionary" reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics.
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The concentrations of the general neuronal markers D2-protein (N-CAM), D3-protein and neuron specific enolase (NSE) in reaggregating cultures of fetal rat telencephalon cells were affected by the presence of 30 nM triiodothyronine in the defined culture medium. The extent of normal developmental changes were enhanced by triiodothyronine, as demonstrated by crossed immunoelectrophoresis. From 13 to 19 days in culture, the concentration of D2-protein decreased, and the concentrations of both D3-protein and NSE increased. Nerve growth factor (NGF) was without effect on the development of these general neuronal markers. However, as shown previously both triiodothyronine and NGF increased the activity of choline acetyltransferase, a marker for cholinergic neurons. The results suggest an enhanced overall differentiation of several types of telencephalon neurons in the presence of triiodothyronine, and a specific stimulation of cholinergic telencephalon neurons by NGF.