Changes in estrogen receptor expression in the chick thymus during late embryonic development

In chickens, although estrogen receptors (ER) are reported to be associated with the immunological processes, detailed information about the differences in ER expression in the tissues related to the development of lymphocytes is not fully known, especially during the developmental stage. To learn more about this immunological relationship, we used semi‐quantitative polymerase chain reaction method to detect the ER expression levels in the thymus tissues of chicks during the developmental stage. Furthermore, ER‐expressing cells were detected by immunohistochemistry. The results of this study show that the expression level of ER increased on embryonic day 16 and decreased on day 20. Furthermore, ER expression was significantly higher in male than in female chickens at day 16. The increased expression on day 16 and decreased level on day 20 were also reproduced in the incidence of immunoreactive cells, although there was a 1‐day delay in the elevated incidence of the cells. This study revealed the changes in ER expression and the incidence of ER‐positive cells in the thymus of chickens during the developmental stage.     

农户金融借贷需求的地区差异及影响因素的实证分析——基于20040个样本调查的经验检验

基于中国人民银行农户借贷情况问卷调查的微观数据,统计分析后发现农户金融借贷需求在地区间具有显著差异,形成地区间4类主导的借贷机构;在地区间影响因素分析上,运用Probit方法,引入影响农户借贷行为的5大类特征变量,揭示特征变量与农户金融借贷需求地区差异关系。结果表明:农户资产存量因素、农户与金融机构之间的互动机制是影响农户金融需求地区差异的主导因素,农户家庭基本情况、人力资本水平、资金用途对借贷地区差异相对弱化。最后,就如何实现我国农村金融差异化平稳发展提出了针对性的政策建议。     

南京小龙山植物内生与土壤微生物群落差异及其矿物风化功能的研究计划项目

以南京小龙山植株海州香薷、根际土壤与非根际土壤作为材料得到可培养的植物内生细菌、根际细菌与非根际细菌,通过研究样品间的群落差异,来分析所得菌种对植株、土壤的作用与影响.将可培养细菌加入钾长石中,通过测定分析不同生境细菌对矿物的风化能力,筛选出具有高效释放矿质元素能力的菌株.该研究有助于丰富微生物资源库,了解植物内生细菌与不同土壤微生物的作用与联系,为深入阐明细菌的矿物风化作用机制打下基础.     

杉木—千年桐人工混交林种内种间竞争关系分析

采用Hegyi单木竞争指数模型对闽北地区3-5年生杉木—千年桐混交林及杉木纯林的种内种间竞争强度进行定量分析。结果表明,杉桐混交林的竞争强度均高于同龄纯林,随林龄增长,竞争强度逐渐减弱。杉桐混交林中以杉木之间的种内竞争为主导。无论纯林还是混交林,对象木受到的竞争强度基本随径级的增加而减少。杉木对象木的胸径大小与杉木种内、杉桐种间的竞争强度呈幂函数关系,其胸径大小与竞争强度之间呈现显著的负相关关系。由预测结果可知,当杉木胸径达到30 cm后,林分竞争强度趋缓。     

盖子红七彩神仙形态指标分析及其雌雄鉴别模型建立

测定和分析了138尾盖子红七彩神仙的形态学性状,并建立了雌雄个体的判别模型。对22项直观测量性状的主成分分析和21项标准化比例性状的R聚类分析,两者均显示盖子红七彩神仙的个体差异主要集中在体型大小、头部宽度、鱼鳍长度和宽度方面。对21项标准化比例性状进行T-检验,结果表明在雌雄间这些性状均差异不显著。以21项标准化比例性状为预选参数,通过逐步判别,建立了判别方程,对群体识别的正确率为80.2%。用32尾盖子红七彩神仙对这一判别方程进行识别验证,识别的正确率为84.4%。     

Female-biased mortality rate and sexual size dimorphism of migratory masu salmon, Oncorhynchus masou

Abstract –  We examined whether mortality and growth during the migration phase (the lacustrine phase after smolting) differ between sexes in migratory (lake-run) masu salmon ( Oncorhynchus masou ) in a lacustrine population, northern Hokkaido, Japan. The sex ratio of 1+ smolts was more skewed to females than that of the returning adults in three annual cohorts examined, indicating that females have a higher mortality rate during the migration phase. Although there was no difference in smolt length between sexes, female adults were larger in body length than males of the same age: female-biased sexual size dimorphism (SSD) occurs. We suppose that breeding selection favouring a larger body size for females than for males in this population probably requires that females undertake more intensive foraging behaviour with its greater inherent risks but faster growth rates during the migration phase. It therefore seems to be likely that the selection is the ultimate cause of the female-biased mortality rate and SSD.     

Utilization of dietary starch and glucose tolerance in juvenile chinook salmon (Oncorhynchus tshawytscha) of different strains in seawater

Juvenile chinook salmon of three strains responded to inclusion of 28.7% of gelatinized starch in the diet with different degrees of reduction in growth rate and feed efficiency relative to control fish of the respective strains fed a low-starch, high-lipid diet of similar protein (46%) and estimated metabolizable energy content (16 mJ/kg). The productive protein value of the diet was not reduced to the same extent by the high intake of starch. Carcasses of fish fed the high-starch diet contained higher concentrations of protein and lower concentrations of lipid than control fish. The accumulation of liver glycogen in response to the high-starch diet differed among strains. Glucose tolerance curves also varied among strains but were poorly correlated with plasma concentrations of insulin. Tolerance to glucose loading was improved in fish previously fed the high-starch diet.     

通道效应与学习者的个体差异性对多媒体学习效果的实验研究

在以往研究的基础上,通过教学实验来考察多媒体计算机教学环境下,不同呈现方式的视频教学录像片的学习者的个体差异性(只把学习者按照其医学知识经验水平的高低进行划分),以及通道效应是否显著。     

Body shape variation within and among three species of darters (Perciformes: Percidae)

Abstract –  Using geometric morphometric (GM) techniques, we quantified intra and interspecific variation in female body shape using five collections each of Etheostoma caeruleum Storer, Etheostoma nigrum Rafinesque, and Etheostoma stigmaeum (Jordan). Nested multivariate analysis of variance showed significant variation in body shape among populations (Wilks' Λ = 0.0687, F _144,7585.1 = 19.35, P  < 0.0001), as well as among species (Wilks' Λ = 8.7 × 10⁻⁶, F _24,2 = 28.18, P  = 0.0348). Etheostoma caeruleum displayed greater body depth relative to both E. nigrum and E. stigmaeum , whereas E. nigrum displayed a compressed arrangement of mid-body landmarks relative to both E. stigmaeum and E. caeruleum . The broader implications of these findings highlight the value of geometric morphometrics as both an exploratory and analytical approach. Conclusions drawn from comparisons among moderately differentiated darter species in future studies of body size and shape are likely robust to intraspecific variation within species, and will permit more rigorous investigations into the ecomorphology of these benthic stream fishes.