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关键词： Stx2噬菌体   形态特征   酶切多态性   SDS-PAGE  

摘要： 【目的】对8株源自大肠杆菌O157编码Stx2毒素的噬菌体生物学特性进行研究。【方法】丝裂霉素C诱导8株大肠杆菌O157菌株释放噬菌体,采用PCR作初步鉴定,分离、纯化噬菌体基因组,随机引物法地高辛(DIG)标记stx2基因片段作为探针,对纯化的噬菌体采用Southern blot进行Stx2噬菌体再次鉴定,透射电子显微镜观察纯化的8株Stx2噬菌体的形态特征,通过限制性内切酶图谱分析,确定噬菌体的核酸类型和基因组大小、以及限制性内切酶酶切片段多态性,并分析噬菌体的蛋白质组成特征。【结果】Southern blot证实分离的8株噬菌体为Stx2噬菌体,电镜下观察的各株Stx2噬菌体形态一致,头部均为正六边形,尾部很短,属于短尾噬菌体科,各株噬菌体之间存在相同的蛋白结构模式,基因组为双链DNA,限制性内切酶片段长度表现出一定的多态性,噬菌体的基因组大小从48.0～65.3kb不等。【结论】来源不同菌株的8株编码Stx2噬菌体均为短尾噬菌体,其蛋白结构模式一致,但基因组具有不同组成。

关键词： 大型底栖动物   群落结构   生物监测   水质   叹气沟河  

摘要： 2006年4月至2007年3月,对清江流域上游一二级支流——叹气沟河的大型底栖动物群落结构进行了深入研究,并利用生物指数对河流水质进行了评价.结果表明,共采集到大型底栖动物82种,其中水生昆虫7目、27科、45属、70种.群落表现出明显的时空特点,具边缘效应的第2采样点物种最丰富,4月份物种最多,达61种;群落春季的多样性最高,依次为夏季、冬季、秋季;各微生境中共有种占据优势,物种相似性均大于60%;功能摄食群则以收集者占优,共计达55种.群落密度在4月份达到最大,为3293ind./m2;而生物量则在12月份达到最大,为163g/m2.采用Shannon多样性指数、生物指数和科级水平生物指数对叹气沟河水质评价的结果是该河流水质比较清洁.

ISBN: (纸本)9787811174250

关键词： 骨折内固定   生物学接骨   临床应用  

摘要： 本文简要回顾常规内固定(AO)的历史,重点介绍近十年快速发展起来的生物学内固定(BO)的理念和技术,并对AO和BO间关系、存在问题及其在小动物骨折生物学内固定应用进展进行评价与分析。

关键词： 铬   生物学作用   动物  

摘要： 本文主要从铬元素的生物学作用及其在动物生产中的应用做一综述，并对铬的应用前景及研究方向作出总结。Cr^3＋是胰岛素辅助因子GTF的主要活性成分，主要通过GTF协助或增强胰岛素在体内发挥生化作用，强化胰岛素的功能，从而影响碳水化合物、脂类及蛋白质的代谢，改变了它们的沉积和利用方向，进而影响动物的生长、繁殖、产品品质及抗病力。

关键词： 实验动物   微生物学   质量控制   寄生虫学   科学研究   精密仪器   实验研究   灵敏性  

摘要： 实验动物在生命科学研究领域中,已被公认是不可缺少的“活的精密仪器”。既然涉及到精密,就必然要有一定的品质要求和标准,以保证在实验研究中具有良好的灵敏性、准确性和重复性。[第一段]

关键词： mutant   sex chromosome   SNP   speciation  

摘要： The medaka Oryzias latipes is a small egg-laying freshwater teleost, and has become an excellent model system for developmental genetics and evolutionary biology. The medaka genome is relatively small in size, -800 Mb, and the genome sequencing project was recently completed by Japanese research groups, providing a high-quality draft genome sequence of the inbred Hd-rR strain of medaka. In this review, I present an overview of the medaka genome project including genome resources, followed by specific findings obtained with the medaka draft genome. In particular, I focus on the analysis that was done by taking advantage of the medaka system, such as the sex chromosome differentiation and the regional history of medaka species using single nucleotide polymorphisms as genomic markers.

关键词： tardigrades   Ramazzottius varieornatus   tolerance   anhydrobiosis   extremophiles   extreme environments  

摘要： Studies on the ability of multicellular organisms to tolerate specific environmental extremes are relatively rare compared to those of unicellular microorganisms in extreme environments. Tardigrades are extremotolerant animals that can enter an ametabolic dry state called anhydrobiosis and have high tolerance to a variety of extreme environmental conditions, particularly while in anhydrobiosis. Although tardigrades have been expected to be a potential model animal for astrobiological studies due to their excellent anhydrobiotic and extremotolerant abilities, few studies of tolerance with cultured tardigrades have been reported, possibly due to the absence of a model species that can be easily maintained under rearing conditions. We report the successful rearing of the herbivorous tardigrade, Ramazzottius varieornatus, by supplying the green alga Chlorella vulgaris as food. The life span was 35 +/- 16.4 d, deposited eggs required 5.7 +/- 1.1 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90 degrees C and - 196 degrees C, and exposure to 99.8% acetonitrile or irradiation with 4000 Gy He-4 ions. Based on their life history traits and tolerance to extreme stresses, R. varieornatus may be a suitable model for astrobiological studies of multicellular organisms.

关键词： Aging/genetics   Aging/pathology   Aging, Premature/genetics   Aging, Premature/pathology   Animals   Cell Division/genetics   Cockayne Syndrome/genetics   Cockayne Syndrome/pathology   Disease Models, Animal   Humans   Longevity/genetics   Mammals/genetics   Mice   Models, Biological   Systems Biology   Systems Theory  

摘要： Despite recent progress in the identification of genes that iregulate longevity, aging remains a mysterious process. One influential hypothesis is the idea that the potential for cell division and replacement are important factors in aging. In this work, we review and discuss this perspective in the context of interventions in mammals that appear to accelerate or retard aging. Rather than focus on molecular mechanisms, we interpret results from an integrative biology perspective of how gene products affect cellular functions, which in turn impact on tissues and organisms. We review evidence suggesting that mutations that give rise to features resembling premature aging tend to be associated with cellular phenotypes such as increased apoptosis or premature replicative senescence. In contrast, many interventions in mice that extend lifespan and might delay aging, including caloric restriction, tend to either hinder apoptosis or result in smaller animals and thus may be the product of fewer cell divisions. Therefore, it appears plausible that changes in the number of times that cells, and particularly stem cells, divide during an organism's lifespan influence longevity and aging. We discuss possible mechanisms related to this hypothesis and propose experimental paradigms.