Neuer Beitrag zur Determination der Imaginalscheiben beiDrosophila

Summary The temperature effective period for the formation of double antennæ and palpi in the gene-combinationsc ec ct; Dfd ^r-L ends with the second half of the third larval stage. The t.e.p. of the mutantsaristopedia andproboscipedia ends with puparium formation. Thus we have another proof that the imaginal discs ofDrosophila are not definitely determined in the last larval stage.     

Mutationsauslösung beiDrosophila durch Äthylurethan

Summary Injection of sublethal doses of ethylurethane intoDrosophila melanogaster males increases the mutation rate for sex-linked lethals up to about 3.4%, as compared with 0.6% in the controls. In addition, several recessive and dominant visible mutations were obtained in the urethane series, while none were found in the control series. Up to the present there is no evidence for an induction of specific mutations by ethylurethane.     

羊三木油田低阻油层测井评价方法

针对羊三木油田低阻油层.综合地质、钻井特征,对低阻油层成因进行了分析,认为该区低阻油层主要是由于薄层、高束缚水饱和度储层引起.针对羊三木油田的实际情况.提出了区域构造对比法、自然电位减少系数法等低阻油层定性评价方法和针对高束缚水饱和度的双水法、针对薄层处理的高分辨率处理技术等定量评价方法.     

Gains of glycosylation comprise an unexpectedly large group of pathogenic mutations

Mutations involving gains of glycosylation have been considered rare, and the pathogenic role of the new carbohydrate chains has never been formally established. We identified three children with mendelian susceptibility to mycobacterial disease who were homozygous with respect to a missense mutation in IFNGR2 creating a new N-glycosylation site in the IFNgammaR2 chain. The resulting additional carbohydrate moiety was both necessary and sufficient to abolish the cellular response to IFNgamma. We then searched the Human Gene Mutation Database for potential gain-of-N-glycosylation missense mutations; of 10,047 mutations in 577 genes encoding proteins trafficked through the secretory pathway, we identified 142 candidate mutations ( approximately 1.4%) in 77 genes ( approximately 13.3%). Six mutant proteins bore new N-linked carbohydrate moieties. Thus, an unexpectedly high proportion of mutations that cause human genetic disease might lead to the creation of new N-glycosylation sites. Their pathogenic effects may be a direct consequence of the addition of N-linked carbohydrate.     

Polyandrous females avoid costs of inbreeding.

Why do females typically mate with more than one male? Female mating patterns have broad implications for sexual selection, speciation and conflicts of interest between the sexes, and yet they are poorly understood. Matings inevitably have costs, and for females, the benefits of taking more than one mate are rarely obvious. One possible explanation is that females gain benefits because they can avoid using sperm from genetically incompatible males, or invest less in the offspring of such males. It has been shown that mating with more than one male can increase offspring viability, but we present the first clear demonstration that this occurs because females with several mates avoid the negative effects of genetic incompatibility. We show that in crickets, the eggs of females that mate only with siblings have decreased hatching success. However, if females mate with both a sibling and a non-sibling they avoid altogether the low egg viability associated with sibling matings. If similar effects occur in other species, inbreeding avoidance may be important in understanding the prevalence of multiple mating.     

关于鲁滨逊精神的分析

本文试图从论理学角度,历史一自传的角度,以及后殖民主义的角度分析笛福的著名小说《鲁滨逊漂流记》中主人公鲁滨逊及其所．体现的鲁滨逊精神。希望通过多角度的分析,加深对文本的理解和认知,从而为阅读此类荒岛文学作品奠定良好的基础。