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291.
Climate change has been suggested to lead to higher temperature and increased heterotrophy in aquatic systems. The aim of
this study was to test how these two factors affect metazooplankton and food web efficiency (FWE was defined as metazooplankton
production divided by basal production). We tested the following hypotheses: (1) that lower metazooplankton production and
lower FWE would be found in a food web based on heterotrophic production (bacteria) relative to one based on autotrophic production
(phytoplankton), since the former induces a larger number of trophic levels; (2) the metazooplankton in the heterotrophic
food web would contain less essential fatty acids than those from the autotrophic food web; and (3) that higher temperature
would lead to increased FWE. To test these hypotheses, a mesocosm experiment was established at two different temperatures
(5 and 10°C) with a dominance of either autotrophic (NP) or heterotrophic basal production (CNP). Metazooplankton production
increased with temperature, but was not significantly affected by differences in basal production. However, increased heterotrophy
did lead to decreased fatty acid content and lower individual weight in the zooplankton. FWE increased with autotrophy and
temperature in the following order: 5CNP < 10CNP < 5NP < 10NP. Our results indicate that in the climate change scenario we
considered, the temperature will have a positive effect on FWE, whereas the increase in heterotrophy will have a negative
effect on FWE. Furthermore, the quality and individual weight of the metazooplankton will be reduced, with possible negative
effects on higher trophic levels. 相似文献
292.
Bombesin impairs spindle function in mitotic V79 Chinese hamster cells by a receptor-dependent mechanism 总被引:2,自引:0,他引:2
Agneta
nfelt 《Mutation research》1992,270(2):97-102
Bombesin belongs to a family of peptides acting as local hormones with roles in growth regulation, neural function and secretion. Upon binding to its receptor bombesin primarily elicits an increase of inositolphosphates and diacylglycerol, events leading to increased [Ca2+]i and activation of protein kinase C. When asynchronously growing V79 Chinese hamster cells were treated with bombesin in the 10−9−10−7 M concentration range their content of inositolphosphates increased and so did the frequency of mitotic cells with abnormal chromosomal arrangements (c-mitoses). Both effects were abolished by simultaneous addition of the synthetic peptide antagonist D-Arg1,D-Phe5,D-Trpu9-Leu11-substance P that binds to certain bombesin receptors. These results demonstrate that the V79 cells most probably have receptors for bombesin and that the weak but significant c-mitotic effect is mediated by such receptors. 相似文献
293.
294.
The characteristics of the luminol-amplified chemiluminescence (CL) induced in mononuclear phagocytes interacting with PMA, FMLP or ionomycin were determined. Azide reduced the CL activity by more than 80%, while superoxide dismutase and catalase had minor effect on the monocyte CL response. The sensitivity of the monocyte CL response, to the addition of extra peroxidase differed depending on the stimulus used. Furthermore, no direct correlation was obtained between the CL response and superoxide anion or hydrogen peroxide production. In comparison with the response in granulocytes, minor quantitative differences were observed. The mechanism for the light-generating reaction, seems to be the same in both cell types. 相似文献
295.
Johanna C Penell Brenda N Bonnett John Pringle Agneta Egenvall 《Acta veterinaria Scandinavica》2009,51(1):50
Background
Computerized diagnostic information offers potential for epidemiological research; however data accuracy must be addressed. The principal aim of this study was to evaluate the completeness and correctness of diagnostic information in a computerized equine clinical database compared to corresponding hand written veterinary clinical records, used as gold standard, and to assess factors related to correctness. Further, the aim was to investigate completeness (epidemiologic sensitivity), correctness (positive predictive value), specificity and prevalence for diagnoses for four body systems and correctness for affected limb information for four joint diseases. 相似文献296.
Gaucher disease type III (GD) is found at a high frequency in northern Sweden. The contemporary Swedish index families are found in two geographically distinct clusters with the highest world-wide frequency of type III GD. A single T-to-C transition in exon 10 has previously been identified in patients from one of the two isolates and we report there the same mutation in the second isolate. Mutational analysis was combined with a genealogical reconstruction of 19 contemporary index families. Both clusters were traced back to two corresponding pairs of ancestors over a 9–13 generation span. Molecular studies show that the two clusters are compatible with a single founder who arrived in northern Sweden in or before the 16th century. 相似文献