大鼠松果体N-乙酰转移酶基因的昼夜节律性表达

探讨12 h光照、12 h黑暗交替(LD)光制下松果体N-乙酰转移酶(NAT)基因的昼夜节律性表达。SD大鼠在LD光制下饲养4周后,在一昼夜内每隔4h采集一组松果体组织,提取总RNA,进行竞争性定量RT-PCR,测定不同昼夜时点(ZT)样品中NAT基因mRNA的相对表达量。用余弦函数获取节律参数,并经振幅检验分析是否存在昼夜节律。结果表明松果体NAT基因mRNA表达呈现昼夜节律性振荡(P<0.05),峰值(mRNA水平为1.07±0.23)和谷值(mRNA水平为0.61±0.15)分别位于ZT16和ZT4,峰值相位-241.80±14.94,振幅0.23±0.13,中值0.84±0.11。证实LD光制下松果体NAT基因存在明显的昼低夜高节律性表达。     

Molecular mechanisms of spider silk

Spiders spin high-performance silks through the expression and assembly of tissue-restricted fibroin proteins. Spider silks are composite protein biopolymers that have complex microstructures. Retrieval of cDNAs and genomic DNAs encoding silk fibroins has revealed an association between the protein sequences and structure-property relationships. However, before spider silks can be subject to genetic engineering for commercial applications, the complete protein sequences and their functions, as well as the details of the spinning mechanism, will require additional progress and collaborative efforts in the areas of biochemistry, molecular biology and material science. Novel approaches to reveal additional molecular constituents embedded in the spider fibers, as well as cloning strategies to manipulate the genes for expression, will continue to be important aspects of spider biology research. Here we summarize the molecular characteristics of the different spider fibroins, the mechanical properties and assembly process of spidroins and the advances in protein expression systems used for recombinant silk production. We also highlight different technical approaches being used to elucidate the molecular constituents of silk fibers. Received 28 February 2006; received after revision 14 April 2006; accepted 22 May 2006 X. Hu and K. Vasanthavada contributed equally to this work.     

Sperm competition, immunity, selfish genes and cancer

Sperm competition is widespread and has played an important role in shaping male reproductive characters such as testis size and numbers of sperm produced, and this is reflected in the rapid evolution of many reproductive genes. Additionally, sperm competition has been implicated in the rapid evolution of seminal fluids. However, our understanding of the molecular basis of many traits thought to be important in sperm competition is rudimentary. Furthermore, links between sperm competition and a range of issues not directly related to reproduction are only just beginning to be explored. These include associations between sperm competition and selfish genes, immunity and diseases such as cancer.We briefly review these topics and suggest areas we consider worthy of additional research.     

薄壳类零件槽孔加工工艺改进

文章充分考虑了所加工薄壳槽孔类零件的结构特点,在不影响零件加工质量的前提下,利用零件的微变形采用过定位设计专用定位工装夹具,提高了零件的定位刚度;应用铣削主轴与滚轮接触限位成形半弧槽孔加工;选用加工成本更低,生产效率更高的钻铣机床,获得一种操作简单实用、生产效率高、加工成本低的薄壳类零件槽孔加工工艺。     

Male panda (Ailuropoda melanoleuca) urine contains kinship information

Chemical communication plays an important role in kin selection and mate choice in mammals. The covariance of odor-genes of rodents has been documented and kinship odor has been proposed and termed, yet little is known of the relationship between genetic relatedness and chemical composition of kinship odors. Giant pandas (Ailuropoda melanoleuca) rely substantially on chemical communication to mediate their social interactions. To examine the relationship between genetic relatedness and compounds in the urine/anogenital gland secretions, we compared the similarities between genetic relatedness and the chemical profiles of anogenital gland secretions and urine via lineage construction and GC-MS (gas chromatography and mass spectrometry). We found that information about kinship odors was present only in the urine of male adults in the mating season but absent in the non-mating season. Adult females and all sub-adults did not have such kinship odors in either mating or non-mating season. Therefore, kinship odor in the panda was contingent on age, sex, and season. This is the first report about the condition-dependent expression of kinship odor, which may have a sig- nificant implication in the practice of panda conservation in relation to chemical communication and sexual selection.     

力竭运动对小鼠体内脂质过氧化作用及肾上腺超微结构的影响

观察了力竭运动对小鼠体内脂质过氧化作用及对肾上腺超微结构的影响．结果表明：连续７次力竭运动后，小鼠肝内丙二醛（ＭＤＡ）含量明显升高；肾上腺皮质及髓质细胞呈现了高度的可变性．提示力竭运动后，小鼠体内所产生的脂质过氧化代谢产物增加，进而可导致细胞膜系及超微结构的改变     

Circadian rhythms and their mechanisms

Summary Recent work concerning the number, site(s) and means of adjustment to the 24-h day of internal clocks is reviewed. Work on humans is considered wherever possible though much of the work involving ablation and in vitro techniques necessarily involves other species, particularly rodents. It is concluded that, though recent advances have been impressive and present techniques appear likely to continue to produce results and stimulate discussion, more attention should be directed to considering the circadian system as a whole rather than as an assemblage of individual components.     

All in the family: aldose reductase and closely related aldo-keto reductases

Aldose reductase catalyzes the first step in the polyol pathway and is thought to be involved in the pathogenesis of diabetic complications. In addition to polyol synthesis, aldose reductase may have multiple other activities that intersect with signal processing and oxidative defense mechanisms. Multiple aldose reductase-like proteins have been discovered to have structures and catalytic properties that broadly overlap those of aldose reductase. This chapter will summarize new insights into properties and functions of aldose reductase and closely related members of the aldo-keto reductase enzyme superfamily.     

唾液腺素、羧甲基壳聚糖、低分子壳聚糖对豚鼠齿龈炎的疗效

针刺豚鼠牙龈,并用１％正丁酸涂抹伤口引起炎症,分别用２％唾液腺素、２％羧甲基壳聚糖（ＣＭＣＴＳ）、２％低分子壳聚糖（ＬＭＣＴＳ）和蒸馏水涂抹伤口引起炎症研究对齿龈炎的疗效。结果表明：唾液腺素、羧甲基壳聚糖（ＣＭＣＴＳ）、低分子壳聚糖（ＬＭＣＴＳ）对齿龈炎都有一定程度的疗效。     

Expression of human erythropoietin directed by mWAP promoter in mammary gland of transgenic mice

The present work has generated transgenic mice with a hybrid gene construct consisting of genomic sequences encodinghuman erythropoietin (hEPO) and governed by regulatory sequences of mousewhey acidic protein (mWAP). The construct proved effective by transient expression in lactating animal. After introducing hybrid gene construct into single-cell embryo via pronuclear microinjection, surviving embryo are reimplanted into pseudopregnant foster mother mouse. 58 mice of 86 generation zero mice obtained were identified to be positive by PCR-Southern blot and genomic DNA Southern blot methods. The integration rate is 67%.hEPO was expressed in the milk of 16 mice of 39 mice measured byhEPO ELISA kit The expression level gets over 15 μg/mL.