Female choice selects for a viability-based male trait in pheasants

Recent theory on sexual selection suggests that females in species without paternal care choose mates by their secondary sexual characters because these indicate genotypic quality which will be transmitted to the offspring. These ideas are not yet empirically supported as data quantifying the relationship between female mate choice and female reproductive success are lacking. Only in one case, in Colias butterflies, has it been demonstrated unequivocally that females choose 'good genotypes' as mates and there is only one study, on Drosophila, demonstrating that mate choice increases one component of offspring fitness. Spur length of male pheasants (Phasianus colchicus) correlates with various fitness-related properties. We here present the first experimental field data showing that female pheasants select mates on the basis of male spur length and that female mate choice correlates with female reproductive success.     

Mice deficient for Rb are nonviable and show defects in neurogenesis and haematopoiesis.

The retinoblastoma gene, a prototypic tumour-suppressor gene, encodes a nuclear phosphoprotein (Rb). To understand better the role of Rb in development and in tumorigenesis, mice with an insertional mutation in exon 20 of the Rb-1 locus were generated. Homozygous mutants die before the 16th embryonic day with multiple defects. The haematopoietic system is abnormal; there is a significant increase in the number of immature nucleated erythrocytes. In the nervous system, ectopic mitoses and massive cell death are found, particularly in the hindbrain. All spinal ganglion cells die, but the neural retina is unaffected. Transfer of the human retinoblastoma (RB) mini-transgene into the mutant mice corrects the developmental defects. Thus, Rb is essential for normal mouse development.     

Female transference and mate choice among Tana River red colobus.

Red colobus are one of a small number of primate species in which females have been reported to transfer between breeding groups more commonly than males. Several authors have hypothesised that in such species transference may serve to reduce the risk to females of producing offspring of lower fitness through inbreeding. The hypothesis offers no explanation of why females rather than males are responsible for outbreeding in these species, but remains plausible so long as male membership of breeding groups is relatively stable; for once members of one sex have evolved dispersal mechanisms reducing the risk of inbreeding, pressures on the other sex to do likewise will be lowered. Hence, if both sexes commonly migrate, the hypothesis is weakened. I describe here the membership dynamics of a group of Tana River red colobus, Colobus badius rufomitratus, which provide the first evidence of high rates of membership turnover by both sexes in primates, and speculate that the function of female transference in this case may be related to mate choice and the avoidance of infanticide.     

臀围和腰围是影响女标准适中体的重要横向部位

应用逐步回归,运用C＋＋语言进行计算,建立女标准适中体控制部位规格尺寸与各细部部位规格间的计算关系．通过对女标准适中体各部位逐步回归的数学模型建立,发现在横向部位中臀围、腰围对女标准适中体各部位结构设计数学模型的影响最大,此结论将为服装企业提供制板经验,为服装CAD技术应用于服装样板设计方法研究打下坚实的理论基础．     

从几起“因言获罪案”看行政权力的边界

近年来发生的较有代表性的三起＂因言获罪案＂的共性是政府超越权力边界,滥用行政权;然而政府应该是一个合理界分权利与权力、合理界分权力的政府;政府应该恪守权力边界,加强对公务员尤其是领导干部的法制教育,完善我国的行政程序制度,建立规范的行政问责制度,建设法治政府。     

Internal sequences that distinguish yeast from metazoan U2 snRNA are unnecessary for pre-mRNA splicing

U2 small nuclear RNA is a highly conserved component of the eukaryotic cell nucleus involved in splicing messenger RNA precursors. In the yeast Saccharomyces cerevisiae, U2 RNA interacts with the intron by RNA-RNA pairing between the conserved branchpoint sequence UACUAAC and conserved nucleotides near the 5' end of U2 (ref. 4). Metazoan U2 RNA is less than 200 nucleotides in length, but yeast U2 RNA is 1,175 nucleotides long. The 5' 110 nucleotides of yeast U2 are homologous to the 5' 100 nucleotides of metazoan U2 (ref. 6), and the very 3' end of yeast U2 bears a weak structural resemblance to features near the 3' end of metazoan U2. Internal sequences of yeast U2 share primary sequence homology with metazoan U4, U5 and U6 small nuclear RNA (ref. 6), and have regions of complementarity with yeast U1 (ref. 7). We have investigated the importance of the internal U2 sequences by their deletion. Yeast cells carrying a U2 allele lacking 958 nucleotides of internal U2 sequence produce a U2 small nuclear RNA similar in size to that found in other organisms. Cells carrying only the U2 deletion grow normally, have normal levels of spliced mRNA and do not accumulate unspliced precursor mRNA. We conclude that the internal sequences of yeast U2 carry no essential function. The extra RNA may have a non-essential function in efficient ribonucleoprotein assembly or RNA stability. Variation in amount of RNA in homologous structural RNAs has precedence in ribosomal RNA and RNaseP.     

全基因组关联分析显示基因ANXA8和C10orf11为影响肌少症的候选基因

为了寻找与瘦体重(lean body mass,LBM)相关的单核苷酸多态性(single nucleotide polymorphism, SNP)位点及易感基因,在1 000个不相关的白人中采用Affymetix 500K芯片扫描了500 000个SNPs,并进行全基因组关联分析(genome-wide association study,GWAS),显著结果在1 625个中国人样本和2 283个欧洲白人样本中进行验证,并将验证结果与研究结果进行荟萃分析。研究发现SNPsrs7905603,rs9416083,rs4409772,rs2894310与LBM关联,其中rs7905603位于基因ANXA8,其他3个SNPs位于基因C10orf11。荟萃分析得到的合并p值分别为2.08×10-5,7.44×10~(-6),6.73×10~(-6),6.76×10~(-6)。ANXA8和C10orf11基因是影响LBM变异的候选基因,这对肌少症的认识提供了新的理论依据。     

邓小平与毛泽东关于事物矛盾的思想认识之比较

邓小平与毛泽东关于事物矛盾的思想认识具有不同的特点。他们对于矛盾的两种基本属性，社会主义社会的基本矛盾，社会主义社会的主要矛盾，社会主义社会的两类矛盾等问题的分析，都显现出一定的差异。这种差异既有深刻的社会历史根据，也有个人认识风格的原因。     

承包土地流转价格低廉的原因及对策

为了搞活土地使用权，政府允许农民承包土地有偿流转，可是实际上，土地流转的价格极其低廉，有些甚至送给其他人耕都没有人要。这种情况就障碍了土地市场的形成，不利于土地的优化配置，本文从多方面分析了土地价格低廉的原因，并在此基础上提出了提高土地流转价格的政策思考。     

费马数是合数的一个充要条件

文章运用数论中的一些简单结果,如(F_m,F_n)=1及F_n=2~(2~n)+1(n≥2)的素因数p具有形状p=2~(n+2)k+1,其中k为某正整数等,给出了费马数是合数的一个充要条件,并得到了F_5,F_6和F_7的素因数分解式。     

Demonstration by monoclonal antibodies that carbohydrate structures of glycoproteins and glycolipids are onco-developmental antigens

The hope that hybridoma antibodies would reveal unique cell surface antigens during embryogenesis, differentiation and oncogenesis has been replaced by the realization that such antigens are mainly carbohydrate structures of glycoproteins and glycolipids occurring in many cell types. These findings either may reflect limitations in the methods of selection of hybridoma antibodies or may point to important roles for the diverse carbohydrate structures as receptors for regulators of cell growth and differentiation.     

单叶调和函数及其反函数为调和拟共形的充要条件

研究平面上具有形式f(z)=A[αz+β+log(1-exp(-αz-β))-log(1-exp(-αz-β))]+B的保向单叶调和映照,其中A,B,α,β是常数且满足条件A≠0,α≠0.给出了定义在椭圆和上半平面上的单叶调和函数及其反函数都是调和拟共形映照的充要条件,并推广到一般的单连通区域上.     

阿托品与有机磷农药中毒

阿托品系抢救有机磷农药中毒的特效解毒剂，在临床使用中，应注意早期，足量，个体化用药，同时，还必须严密观察体征，排除各种干扰，以期提高抢救成功率。     

3S技术在青藏高原研究中的应用前景分析

介绍了3S(GIS,RS,GPS)技术的特点及最新进展,总结了3S技术在青藏高原研究的现状和取得的成果,分析了3S技术在青藏高原研究中的应用前景,并设计了3S技术在高原研究中的集成框架.并指出基于GIS的高原研究数据、资料、成果的数据库建设和信息共享,高原三维地形模型建设及古地形的三维再造,高原地区的地学信息图谱研究是当前3S技术在高原研究中的重要领域和基础.     

高校就业难问题成因分析及对策

近年来,我国大学毕业生就业难已成为全社会关注的热点问题。教育主管部门信息显示,2000年6月,我国高校毕业生中待业人数30万左右,2003年为52万人,2005年更达到了75万人。大学毕业生是国家的宝贵财富,是人力资源的主要来源和组成部分,而人力资源是一个国家发展的第一资源。无论从数据统计还是从实际状况来看,我们的人力资源,尤其是大学毕业生不是太多而是太少。我国大学生毛入学率仅15%左右,而美国为82%,日本、英国、法国等发达国家均在50%以上,韩国、印度、菲律宾也在30%左右。我国7亿多庞大的从业人员中,高层次人才稀缺,受过高等教育的仅为5%左右。因此,出现大学生就业难,并非是数量问题,主要的还是管理上的问题。