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排序方式: 共有81条查询结果,搜索用时 15 毫秒
1.
In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed. 相似文献
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Alex Gutteridge J. Michael Rukstalis Daniel Ziemek Mark Tié Lin Ji Rebeca Ramos-Zayas Nancy A. Nardone Lisa D. Norquay Martin B. Brenner Kim Tang John D. McNeish Rebecca K. Rowntree 《PloS one》2013,8(2)
We have used a previously unavailable model of pancreatic development, derived in vitro from human embryonic stem cells, to capture a time-course of gene, miRNA and histone modification levels in pancreatic endocrine cells. We investigated whether it is possible to better understand, and hence control, the biological pathways leading to pancreatic endocrine formation by analysing this information and combining it with the available scientific literature to generate models using a casual reasoning approach. We show that the embryonic stem cell differentiation protocol is highly reproducible in producing endocrine precursor cells and generates cells that recapitulate many aspects of human embryonic pancreas development, including maturation into functional endocrine cells when transplanted into recipient animals. The availability of whole genome gene and miRNA expression data from the early stages of human pancreatic development will be of great benefit to those in the fields of developmental biology and diabetes research. Our causal reasoning algorithm suggested the involvement of novel gene networks, such as NEUROG3/E2F1/KDM5B and SOCS3/STAT3/IL-6, in endocrine cell development We experimentally investigated the role of the top-ranked prediction by showing that addition of exogenous IL-6 could affect the expression of the endocrine progenitor genes NEUROG3 and NKX2.2. 相似文献
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The ubiquitin-proteasome pathway plays a critical role in the degradation of several proteins involved in the cell cycle. Dysregulation of this pathway leads to inhibition of cellular proliferation and the induction of apoptosis. Ubiquitination and its downstream consequences have been investigated intensively as targets for the development of drugs for tumour therapy. Here we have investigated the mechanism of apoptosis induced by the proteasome inhibitors MG-132, lactacystin and calpain inhibitor I (ALLN), in the HEK 293 cell line and the ovarian cancer cell lines SKOV3 and OVCAR3. We have found strong caspase-3-like and caspase-6-like activation upon treatment of HEK 293 cells with MG-132. Using a tricistronic expression vector based on a tetracycline-responsive system we generated stable SKOV3 nd OVCAR3 cell lines with inducible expression of pro-caspase-3. Induction of pro-caspase-3 expression in normally growing cells does not induce apoptosis. However, in the presence of the proteasome inhibitors MG-132, lactacystin or ALLN we found that cells overexpressing pro-caspase-3 are rapidly targeted for apoptosis. Our results demonstrate that pro-caspase-3 can sensitise ovarian cancer cells to proteasome inhibitor-induced apoptosis, and a combination of these approaches might be exploited for therapy of ovarian and other cancers. 相似文献
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Ke HZ Brown TA Qi H Crawford DT Simmons HA Petersen DN Allen MR McNeish JD Thompson DD 《Journal of musculoskeletal & neuronal interactions》2002,2(5):479-488
The molecular and cellular mechanism of estrogen action in skeletal tissue remains unclear. The purpose of this study was to understand the role of estrogen receptor-beta, (ERbeta) on cortical and cancellous bone during growth and aging by comparing the bone phenotype of 6- and 13-month-old female mice with or without ERbeta. Groups of 11-14 wild-type (WT) controls and ERbeta knockout (BERKO) female mice were necropsied at 6 and 13 months of age. At both ages, BERKO mice did not differ significantly from WT controls in uterine weight and uterine epithelial thickness, indicating that ERbeta does not regulate the growth of uterine tissue. Femoral length increased significantly by 5.5% at 6 months of age in BERKO mice compared with WT controls. At 6 months of age, peripheral quantitative computerized tomography (pQCT) analysis of the distal femoral metaphysis (DFM) and femoral shafts showed that BERKO mice had significantly higher cortical bone content and periosteal circumference as compared with WT controls at both sites. In contrast to the findings in cortical bone, at 6 months of age, there was no difference between BERKO and WT mice in trabecular density, trabecular bone volume (TBV), or formation and resorption indices at the DFM. In 13-month-old WT mice, TBV (-41%), trabecular density (-27%) and cortical thickness decreased significantly. while marrow cavity and endocortical circumference increased significantly compared with 6-month-old WT mice. These age-related decreases in cancellous and endocortical bone did not occur in BERKO mice. At 13 months of age, BERKO mice had significantly higher total, trabecular and cortical bone, while having significantly lower bone resorption, bone formation and bone turnover in DFM compared with WT mice. These results indicate that deleting ERbeta protected against age-related bone loss in both the cancellous and endocortical compartments by decreasing bone resorption and bone turnover in aged female mice. These data demonstrate that in female mice, ERbeta plays a role in inhibiting periosteal bone formation, longitudinal and radial bone growth during the growth period, while it plays a role in stimulating bone resorption, bone turnover and bone loss on cancellous and endocortical bone surfaces during the aging process. 相似文献
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In vitro neuronal recordings in the SCN have clearly documented shifts in the peak of unit activity following the application of serotonergic agents, and yet selectivity issues with these very tools have limited progress in establishing the precise receptor mechanisms. As an alternative strategy, mice were bred (C57BL/6J) lacking 1 serotonin receptor, the 5-HT(7), to serve as a null background for this subtype; earlier work had documented the involvement of 5-HT(7) receptors in the phase advances elicited by 8-OH-DPAT, a mixed 5-HT(1A/7) agonist, in SCN slices prepared from rat donors. Single-unit recordings in sequential electrode passes revealed peaks of activity that occurred at nearly the same time in the knockout (KO; ZT4.2 +/- 0.6) and wild-type animals (WT; ZT4.3 +/- 0.1), where ZT0 marks the beginning of the light phase in a 12:12 LD cycle. Bath application of 8-OH-DPAT produced a phase advance in neuronal firing (2.1 +/- 0.5 h) when applied 1 circadian cycle earlier at ZT6 (10 microM, 10 min), but surprisingly, the mean phase advance in slices prepared from KO mice (2.3 +/- 0.1 h) was no different. Coapplication of 8-OH-DPAT with WAY-100,635 (10 microM), a highly selective 5-HT(1A) antagonist, significantly reduced the phase advance, both in experiments with WT and KO mice, suggesting the greater importance of this serotonin sub-type independent of genetic modification. 5-HT itself (0.5 +/-M, 10 min) at ZT6 also yielded phase advances that were indistinguishable in slices prepared from WT and KO mice (1.8 +/- 0.4 h and 2.1 +/- 0.2 h, respectively) and that were also sensitive to WAY-100,635. Unlike the pattern with 8-OH-DPAT, however, 5-HT-induced phase advances, in both WT and KO mice, were blocked by ritanserin, in this paradigm useful as a 5-HT(5A/7) antagonist (in addition to its more typical role as a 5-HT2A/2C antagonist). Serotonin antagonists when administered alone were without effect in slices from WT mice but produced significant phase shifts when administered to those from KO animals. Taken together, these results highlight the importance of the species used in establishing receptor mechanism. More provocatively, they support the involvement of multiple serotonin receptors in shifting the phase of circadian rhythms at ZT6. 相似文献
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Alister J. McNeish Francesc Jimenez-Altayo Graeme S. Cottrell Christopher J. Garland 《PloS one》2012,7(10)