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201.
1. Spatial patterns in channel morphology and substratum composition at small (1–10 metres) and large scales (1–10 kilometres) were analysed to determine the influence of habitat heterogeneity on the distribution and abundance of larval lamprey. 2. We used a nested sampling design and multiple logistic regression to evaluate spatial heterogeneity in the abundance of larval Pacific lamprey, Lampetra tridentata, and habitat in 30 sites (each composed of twelve 1‐m2 quadrat samples) distributed throughout a 55‐km section of the Middle Fork John Day River, OR, U.SA. Statistical models predicting the relative abundance of larvae both among sites (large scale) and among samples (small scale) were ranked using Akaike's Information Criterion (AIC) to identify the ‘best approximating’ models from a set of a priori candidate models determined from the literature on larval lamprey habitat associations. 3. Stream habitat variables predicted patterns in larval abundance but played different roles at different spatial scales. The abundance of larvae at large scales was positively associated with water depth and open riparian canopy, whereas patchiness in larval occurrence at small scales was associated with low water velocity, channel‐unit morphology (pool habitats), and the availability of habitat suitable for burrowing. 4. Habitat variables explained variation in larval abundance at large and small scales, but locational factors, such as longitudinal position (river km) and sample location within the channel unit, explained additional variation in the logistic regression model. The results emphasise the need for spatially explicit analysis, both in examining fish habitat relationships and in developing conservation plans for declining fish populations. 相似文献
202.
半环扁尾海蛇神经毒素的融合表达及活性检测 总被引:1,自引:1,他引:1
目的:将海蛇神经毒素基因克隆到融合表达载体pET32a中,诱导表达海蛇神经毒素,鉴定融合表达蛋白的生物功能,为大量合成海蛇神经毒素奠定基础。方法:利用融合表达载体将海蛇神经毒素与硫氧还蛋白融合表达,使其在胞内可溶;采用亲和层析与G50凝胶过滤纯化融合蛋白;利用豚鼠直肠纵肌电刺激检验融合蛋白的神经信号阻断功能。结果:得到电泳纯的融合蛋白,该蛋白对豚鼠直肠纵肌电刺激有明显的阻断作用。结论:融合表达能促进海蛇神经毒素的可溶性表达,表达产物能阻断神经信号的传递。 相似文献
203.
从斑鳜(Siniperca scherzeri)背部白色肌肉组织中提取总RNA,利用RT-PCR法克隆到斑鳜肌球蛋白轻链2基因(MLC2)(GenBank:GQ283000).斑鳜MLC2基因cDNA序列的开放阅读框的长度为513 bp,编码170个氨基酸,理论相对分子质量为19 105.61 Da,等电点为4.73.该开放阅读框具有4个EF-手相结构.斑鳜MLC2推导的氨基酸序列与已报道的其它6种鱼类MLC2氨基酸序列同源性在89%以上,其中与Ca2+结合的区域非常保守,氨基酸序列同源性为100%.用实时荧光定量PCR对斑鳜MLC2纵向表达分析显示,MLC2在斑鳜背肌的前部、中部和后部都有表达,但无显著差异. 相似文献
204.
We compared the number/percentages of naive and memory CD4+ T-cells, CD38+ CD8+ T-cells, and CD28+ CD4+ and CD28+ CD8+ T-cells in patients with advanced HIV disease (baseline CD4+ count < 100) with those with less advanced (baseline CD4+ cell count > 100) HIV disease during 4 years of suppressive highly active antiretroviral therapy. This prospective, longitudinal study included 30 treatment-naive patients and 32 controls. Advanced HIV-infected patients (n = 13) gained more CD4+ T-cells than less advanced patients (n = 11) at 1 month (median: 60 vs. 36 microL(-1)), 3 months (86 vs. 14), 6 months (111 vs. 23), 12 months (174 vs. 47), 24 months (162 vs. 72) and 48 months (257 vs. 123) (P = 0.15, P < 0.001, P = 0.026, P = 0.021, P = 0.1 and P = 0.06, respectively). Advanced patients gained more naive CD4+ T-cells at 48 months compared to less advanced patients (27.3 vs. 11.4%, P = 0.05). The relative gain in memory CD4+ T-cells was greater in advanced vs. less advanced patients at 1 month (median: 6.4 vs. 1.4%), 3 months (4.3 vs. 2.0), 6 months (6.7 vs. 1.6), 12 months (6.9 vs. 2.4), 24 months (7.5 vs. 3.1) and 48 months (11.3 vs. 6.8) (P = 0.002, P = 0.013, P < 0.001, P = 0.004, P = 0.001 and P = 0.015, respectively). At 48 months, CD38+ CD8+ T-cells and naive CD4+ T-cells reached normal values (9.2%, P = 0.869 vs. controls and 47.5%, P = 0.699, respectively) in less advanced patients, as did CD38+ CD8+ T-cells in advanced patients (4.7%, P = 0.309 vs. controls). The kinetics of naive and memory CD4+ T-cell reconstitution is different in less advanced compared to advanced HIV patients. 相似文献
205.
A. M. Sutera V. Riggio S. Mastrangelo R. Di Gerlando M. T. Sardina R. Pong‐Wong M. Tolone B. Portolano 《Animal genetics》2019,50(3):311-314
Genome‐wide association studies (GWASes) have become a powerful tool for identifying genomic regions associated with important traits in livestock. Milk production traits in dairy sheep are measured at different time points during their life span. Using phenotypic data generated from longitudinal traits could improve the power of association studies but until now have received less attention in GWASes as a methodology and has not been implemented. The aim of this study was to carry out a GWAS for milk production traits in Valle del Belice sheep using repeated measures. After quality control, 469 ewes and 37 228 SNPs were retained for the analysis, and phenotypic data included 5586 test‐day records for five milk production traits (milk yield, MY; fat yield and percentage, FY and F%; protein yield and percentage, PY and P%). Nine SNPs located within or close to known genes were found to be associated with milk production traits. In particular, rs398340969, associated with both milk yield and protein yield, is located within the DCPS gene. In addition, rs425417915 and rs417079368, both associated with both fat percentage and protein percentage, are located within the TTC7B gene and at 0.37 Mb within the SUCNR1 gene respectively. In summary, the use of repeated records was beneficial for mapping genomic regions affecting milk production traits in the Valle del Belice sheep. 相似文献
206.
目的应用超声影象分析评价高脂血症金黄地鼠模型在不同时间点肝脏、主动脉弓部和心脏功能的变化,进一步探讨超声影象分析对高脂血症金黄地鼠不同时期病变的诊断价值。方法 32只叙利亚金黄地鼠分为正常对照组和高脂血症模型组,分别给以正常饲料和高脂饲料,第0、3、6、9、14、16、20、24、40周时监测血脂水平,第20和40周时各组金黄地鼠行超声影象分析和病理学检查。结果高脂饲料喂饲后金黄地鼠血清TC、TG、HDL-C、LDL-C水平显著上升(P〈0.05),随着高脂喂饲时间的延长,不同时间点主动脉弓部内膜-中膜厚度显著增加(P〈0.000 1),超声影象分析和病理学结果均显示高脂喂饲金黄地鼠20周时已形成脂肪肝、主动脉弓部已形成动脉粥样硬化病变,至40周时脂肪肝和动脉粥样硬化病变加重。结论超声影象分析可应用于测量高脂血症金黄地鼠模型主动脉弓部内膜-中膜厚度,连续监测脂肪肝和主动脉弓部动脉粥样硬化病变。 相似文献
207.
Yoko Kameda 《Cell and tissue research》2009,336(2):165-178
Anomalies of the aortic arch have long been of anatomicoclinical interest. Recent studies on gene-targeted mice have identified
the candidate genes that are involved in the patterning and remodeling of the pharyngeal arch arteries. In this review, we
discuss our present knowledge with regard to the signaling molecules that regulate specific aspects of arch artery development.
We focus first on Hoxa3, because it plays a critical role in the regulation of the differentiation of the third pharyngeal
arch. Hoxa3 is expressed by the neural crest cells that originate from the rhombomeres, viz., (r)5, r6, and r7, and populate
the third pharyngeal arch; it is also expressed in the third pharyngeal pouch. In Hoxa3 homozygous null mutant mice, the third arch artery degenerates bilaterally at embryonic day 11.5, resulting in the malformation
of the carotid artery system. Complex combinatorial signals among the neural crest cells, pharyngeal mesoderm, ectoderm, and
pouch endoderm are required for the proper development of the arch arterial system. Therefore, we highlight the numerous signaling
pathways and individual genes expressed by the ectomesenchymal neural crest cells and also by the other epithelial and mesodermal
cells of the pharynx. Defects in these genes result in malformations of the arch artery derivatives. This review should deepen
our understanding of congenital human syndromes with abnormal patterns of pharyngeal arch arteries. 相似文献
208.
Bobkov AA Muhlrad A Kokabi K Vorobiev S Almo SC Reisler E 《Journal of molecular biology》2002,323(4):739-750
Structural effects of yeast cofilin on skeletal muscle and yeast actin were examined in solution. Cofilin binding to native actin was non-cooperative and saturated at a 1:1 molar ratio, with K(d)相似文献
209.
Jennifer Fairlie Rebecca Holland Jill G. Pilkington Josephine M. Pemberton Daniel H. Nussey 《Aging cell》2016,15(1):140-148
Telomeres play a fundamental role in the maintenance of genomic integrity at a cellular level, and average leukocyte telomere length (LTL) has been proposed as a biomarker of organismal aging. However, studies tracking LTL across the entire life course of individuals are lacking. Here, we examined lifelong patterns of variation in LTL among four birth cohorts of female Soay sheep (Ovis aries) that were longitudinally monitored and sampled from birth to death. Over the first 4 months of life, there was within‐individual loss of LTL, consistent with findings in the human and primate literature, but there was little evidence of consistent LTL loss associated with age after this point. Overall, we observed only weak evidence of individual consistency in LTL across years and over the entire lifespan: Within‐individual variation was considerable, and birth cohorts differed markedly in their telomere dynamics. Despite the high levels of LTL variation within the lifetimes of individuals, there remained significant associations between LTL and longevity. Detailed analysis of the longitudinal data set showed that this association was driven by improved survival of individuals with longer LTL over the first 2 years of life. There was no evidence that LTL predicted survival in later adulthood. Our data provide the first evidence from a mammal that LTL can predict mortality and lifespan under natural conditions, and also highlight the potentially dynamic nature of LTL within the lifetimes of individuals experiencing a complex and highly variable environment. 相似文献
210.