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1.
对我国52种微茎类吸虫的18项成虫形态学特征进行主成分分析,结果表明:卵巢位置、子宫延伸位置等7项性状对第一主成分贡献较大,提示描述器官位置的指标是重要的分类依据。52个虫种在前三个主成分上的排序图显示应将其划分成4个亚科。 相似文献
2.
Genotype-Environment Interaction: Apolipoprotein E (Apoe) Gene Effects and Age as an Index of Time and Spatial Context in the Human 总被引:4,自引:0,他引:4
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We analyzed the age-dependence of the estimates of the parameters of the genetic architecture of plasma ApoE levels associated with ApoE gene variation. Our study sample included 1988 individuals in multigeneration pedigrees from the Rochester, MN, population. We used a 30-yr sliding window across the age range (5-90 yr) to estimate the age dependency of parameters. Additive ApoE allelic variance of transformed plasma ApoE values for both genders, heritabilities for males and phenotypic and residual variance for females peaked in the 20-40-yr age windows and decreased significantly with age (P < 0.05). Phenotypic and residual variance for males and dominance variance for both genders did not vary significantly with age. All parameter estimates were significantly different from zero across all age windows for both genders. Most studies of ApoE have focused on its functions in the pathophysiology of coronary artery disease (CAD) in middle-aged and older individuals. Our findings suggest the greatest role of this gene is in determining phenotypic differences among younger and middle-aged individuals. These observed genotypic effects on the plasma ApoE levels may contribute to age-dependent differences in physiological health, growth, and risk of disease. 相似文献
3.
本文就萤叶甲亚科中柱萤叶甲属鞘翅具黑色刻点的种类进行研究,共记述4种,我国已记录3种,其中1种为新种。 相似文献
4.
5.
The tiger salamander,Ambystoma tigrinum, is a geographically widespread, morphologically variable, polytipic species. It is among the most variable species of salamanders
in morphology and life history with two larval morphs (typical and cannibal) and three adult morphs (metamorphosed, typical
branchiate, cannibal branchiate) that vary in frequency between subspecies and between populations within subspecies. We report
morphometric evidence suggesting that branchiate cannibals arose through intraspecific change in the onset or timing of development
resulting in the wider head and hypertrophied tooth-bearing skull bones characteristic of this phenotype. We also quantified
bilateral symmetry of gill raker counts and abnormalities, then evaluated fluctuating asymmetry as a measure of the developmental
stability of each morph. There was a significant interaction between fluctuating asymmetry of developmental abnormalities
in cannibals and typicals and the locality where they were collected, suggesting that relative stability of each phenotype
could vary among populations. While altered timing of developmental events appears to have a role in the evolution and maintenance
of morphs, novel phenotypes persist only under favorable ecological conditions. Predictability of the aquatic habitat, genetic
variation, kinship, body size, intraspecific competition and predation all affect expression and survival of the morphs inA. tigrinum. This taxon provides an excellent model for understanding the diversity and complexity of developmental and ecological variables
controlling the evolution and maintenance of novel phenotypes. 相似文献
6.
本文报道在湛江市附近海域海鸟体内获得的两种吸虫,经鉴定为新种,命名为巨口类茎吸虫,新种Microphalloides macrostonrs sp.nov.,珊瑚多黄吸虫,新种Multivitellus coralius sp.nov. 相似文献
7.
以化学纯饲料饲养北京的桃蚜 总被引:4,自引:0,他引:4
应用修改后的Dadd和Mitter(1966)全纯饲料配方配制成人工饲料饲养定居在北京温室烟草上的桃蚜 Myzus persicae可完成生活史井连续饲养3代。本文描述饲料配制、饲养和取食量测定的方法。这3代初羽化无翅孤雌胎生雌蚜的平均体重分别为:440±90.7μg,264±104.9μg和312±127.9μg。用放射性同位素稀释法测定取食量的结果得悉若虫期的总取食量每蚜约为1.74μg,相当于1.16μl。 相似文献
8.
小麦倒春寒研究现状与进展 总被引:1,自引:0,他引:1
由于全球气候变暖,近年来小麦低温灾害事件频发,尤其是拔节-孕穗期的倒春寒灾害已成为制约小麦产量和品质的重要因素之一。本文综述了小麦倒春寒灾害的发生特点(鉴定与分级、时空特征),倒春寒对小麦生理特性(叶片、茎秆、穗部、根系)和产量、质量的影响,总结了抗倒春寒小麦育种、倒春寒危害的分子生物学机制及灾害的监测预警与风险评估等方面的研究进展,并从小麦抗倒春寒遗传基础、倒春寒危害小麦评价体系和防控技术体系等方面进行了展望,以期为抗倒春寒小麦品种的遗传改良和栽培调控新措施的建立提供理论依据。 相似文献
9.
小麦族(Triticeae)是禾本科、早熟禾亚科中一个有重要经济价值、以多年生植物占优势的族,族内绝大多数种类是重要的粮食作物和畜牧业上的优良牧草,饲用价值极高,有些种类具有耐寒、耐旱、耐碱等特性,是农牧业上良种繁育、牧草利用的重要基因资源。但该族同时又是分类学上的一个疑难族,各学者对族内系统分类意见不一、争议颇大,尤其在族的界限、族下类群划分以及类群演化关系上问题较多,至今尚未解决。查阅了国内外分类学文献,探讨其分类差异以及存在问题,为充分开发利用中国丰富的小麦族植物资源提供理论依据。 相似文献
10.
Summary At metamorphosis the attachment of the Plumatella larva to the substrate is effected by secretions from glandular cells in the apical plate, the leading pole during swimming. The larval mantle folds back and slides down towards the substrate. By ciliary activity an adhesive secretion is spread over the metamorphosing larva and the attachment area. Two polypides appear through the larval terminal opening. The mantle fold, together with gland cells, nerve cells, sensory cells, and muscle cells from the larva form a nutritive cell mass. Reduction of this nutritive cell mass is accomplished by autolysis and phagocytosis. An invaginated area of the nutritive cell mass is provided with a dense layer of microvilli, which seem to have an absorbtive function. The nutritive cell mass consisting of transitory larval tissues provides a significant source of nutrient for the developing polypide buds. 相似文献