西藏乃东县发现豆雁

正2016年1月6日,在西藏自治区乃东县泽当镇羌哉村(29°16′29.634″N,95°49′44.202″E,海拔3 557 m)观察到2只雁,该雁全身以灰褐色为主,尾下覆羽为白色,脚为橙黄色,喙黑色、喙端有黄斑,嘴甲和鼻孔间有白色斑点,两胁具灰褐色黄斑。经鉴定为豆雁(Anser fabalis)(约翰·马敬能等2000,Mark 2009,曲利明2014)。查阅相关文献(中国科学院青藏高原综合科学考察队1983,赵正阶2001,郑光美2011,刘迺发等2013),确认     

Influence of Infected Cell Growth State on Bacteriophage Reactivation Levels

Reactivation of UV-C-inactivated Pseudomonas aeruginosa bacteriophages D3C3, F116, G101, and UNL-1 was quantified in host cells infected during the exponential phase, during the stationary phase, and after starvation (1 day, 1 and 5 weeks) under conditions designed to detect dark repair and photoreactivation. Our experiments revealed that while the photoreactivation capacity of stationary-phase or starved cells remained about the same as that of exponential-phase cells, in some cases their capacity to support dark repair of UV-inactivated bacteriophages increased over 10-fold. This enhanced reactivation capacity was correlated with the ca. 30-fold-greater UV-C resistance of P. aeruginosa host cells that were in the stationary phase or exposed to starvation conditions prior to irradiation. The dark repair capacity of P. aeruginosa cells that were infected while they were starved for prolonged periods depended on the bacteriophage examined. For bacteriophage D3C3 this dark repair capacity declined with prolonged starvation, while for bacteriophage G101 the dark repair capacity continued to increase when cells were starved for 24 h or 1 week prior to infection. For G101, the reactivation potentials were 16-, 18-, 10-, and 3-fold at starvation intervals of 1 day, 1 week, 5 weeks, and 1.5 years, respectively. Exclusive use of exponential-phase cells to quantify bacteriophage reactivation should detect only a fraction of the true phage reactivation potential.     

Susceptibility of Adenovirus 2-transformed rat cell lines to natural killer (NK) cells: direct correlation between NK resistance and in vivo tumorigenesis

The susceptibility to natural killer (NK)-mediated cell lysis of Adenovirus type 2 (Ad2)-transformed rat embryo fibroblast cell lines, which differed markedly in tumorigenic potential in vivo (T2C4 greater than F19 greater than F17), was investigated by using NK effector cells from F344 rat or athymic nude rat spleens. A comparison of the degree of NK-mediated lysis obtained with these tumor cell targets suggested a direct relationship between the resistance of a cell to NK cell lysis and its potential to form tumors in vivo. The cells were lysed in the following order of increasing susceptibility: T2C4 less than F4 less than F19 less than F17. Whether T cells or macrophages played a significant role in the observed lytic activity was determined by treating the NK effector cell population with anti-rat T cell serum (alpha T) and complement or by depletion of macrophages after binding to a glass bead column and treatment with carbonyl iron. A series of clonal sublines derived from the parental F17 and F4 cell lines further strengthened this relationship between tumorigenesis and resistance to NK-mediated cell lysis. Tumorigenic subclones from the non-tumorigenic F17 parental cells were demonstrated to be comparatively resistant to NK-mediated lysis. Tumorigenic subclones from tumorigenic F4 parental cell population showed a susceptibility to NK-mediated cell lysis virtually identical to the parental F4 cells. The implication of these results are discussed.     

Identification of proteins encoded by the L1 and L2 open reading frames of human papillomavirus 1a.

The human papillomavirus 1 (HPV-1) virion is composed of two virally encoded proteins: a 57,000-molecular-weight polypeptide (57K polypeptide), which is the product of the L1 open reading frame (ORF), and a 78K polypeptide, which is derived from the L2 ORF. The 57K (L1) product, which represents the major structural component, appears to be disulfide cross-linked in virus particles. The 78K (L2) protein is a minor component of the virion and does not appear to be disulfide linked either to the L1 gene product or to itself. Analysis of virus particles banding at different buoyant densities revealed differences in the L2 content of heavy-full and light-full virions. Antiserum prepared against a bacterially expressed fragment of the L1 ORF was found by immunofluorescence to cross-react with HPV-2 and bovine papillomavirus 1 virions in wart sections. No cross-reactivity was observed with antisera prepared against either the N- or C-terminal halves of the L2-encoded protein. Similarly, antisera prepared against purified virus particles (disrupted and nondisrupted) reacted only with an expressed fragment of the L1 ORF and not with either L2-encoded polypeptides or proteins derived from the E1, E2, E4, E6, or E7 ORFs. This indicates that the L1 protein contains the papillomavirus common antigens.     

Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila: II. Divergence versus polymorphism

The evolution of the gene for a male ejaculatory protein, Acp26Aa, has been shown to be driven by positive selection when nonsibling species in the Drosophila melanogaster subgroup are compared. To know if selection has been operating in the recent past and to understand the details of its dynamics, we obtained DNA sequences of Acp26Aa and the nearby Acp26Ab gene from 39 D. melanogaster chromosomes. Together with the 10 published sequences, we analyzed 49 sequences from five populations in four continents. The southern African population is somewhat differentiated from all other populations, but its nucleotide diversity is lower at these two loci. We find the following results for Acp26Aa: (1) The R: S (replacement : silent changes) ratio is significantly higher in the between-species comparisons than in the within-species data by the McDonald and Kreitman test. Positive selection is probably responsible for the excess of amino acid replacements between species. (2) However, within-species nucleotide diversity is high. Neither the Tajima test nor the Fu and Li test indicates a reduction in nucleotide diversity due to positive selection in the recent past. (3) The newly derived nucleotides in D. melanogaster are at high frequency significantly more often than predicted by the neutral equilibrium. Since the nearby Acp26Ab gene does not show these patterns, these observations cannot be attributed to the characteristics of this chromosomal region. We suggest that positive selection is active, but may be weak, for each amino acid change in the Acp26Aa gene.      

包含BTB锌指结构的新基因Bsg2结构特性及其在发育阶段的组织表达特异性

通过消减差异筛选法寻找小鼠胚胎发育过程中在脑中特异表达的基因 .克隆得到的脑特异表达新基因 2 (brainspecificgene 2 ,简称Bsg2 )长 36 91bp ,通过生物信息学方法预测其编码一个含713个氨基酸的锌指蛋白 .此蛋白N端有一个BTB(BR C ,ttkandbab)结构域 ,C端有 9个连续的C2H2锌指结构 .该基因定位在小鼠 12号染色体上 ,包含 1个内含子和 2个外显子 .应用生物信息学和RT PCR方法分别检验该基因在小鼠各组织中的表达 .结果表明 ,Bsg2基因在小鼠胚胎及成体的各组织中普遍表达 ,在脾、肾、睾丸、肠、子宫和脑的表达水平较强 .利用整体 (wholemount)原位杂交研究其时空表达模式 .结果显示 ,Bsg2在早期的小鼠胚胎和不同时期鸡胚的头部均特异表达 ,在11d鼠胚的肢芽里也有较强的表达 .Bsg2基因的结构和表达特征预示它编码 1个具有DNA结合功能的转录调控因子 ,同时揭示它在脑的发育和器官形成过程中发挥着重要作用     

内蒙古呼伦贝尔沙地不同樟子松林竞争强度的比较

利用全林木定位和单木竞争指数模型, 以受到林火干扰的樟子松林为例,分析了呼伦贝尔沙地樟子松林的竞争强度.结果表明：同一样地中,死亡林木的竞争强度均比较接近;活立木、全部林木中,伴生树种的竞争强度是樟子松的2～3倍;樟子松的竞争压力主要来自于种内,伴生树种的竞争则主要来自于种间.林火干扰与无林火（对照）样地间的比较表明,林火干扰样地樟子松活立木的竞争强度均显著小于对照样地;活立木竞争强度与其胸径间均服从幂函数关系(CI=AD^-B).地表火干扰可显著降低林木个体间的竞争强度,有利于存活林木个体的生长发育和大径阶林木的培育.     

Demographic history of the Tibetan antelope Pantholops hodgsoni (chiru)

Abstract The Tibetan antelope (chiru, Pantholops hodgsoni), a heavily poached species and symbol of the Qinghai‐Tibetan Plateau (QTP), is noted worldwide for its special calving migration. This species originated in the early Quaternary and it is interesting to know how the following climatic oscillations affected its demographic dynamics in the climate‐sensitive QTP. In this study, we analyzed the mitochondrial D‐loop region from 312 individuals sampled in all of the six major populations. We found high rates of gene flow and little genetic differentiation between populations, suggesting that the calving migration may have homogenized the genetic pool of this species. Both mismatch distribution analyses and coalescent simulations suggested that this species experienced a demographic expansion approximately 600–200 Kyr following the retreat of the large glaciers developed in the QTP at 800–600 Kyr, rather than at the end of the last glacial age, as previously suggested, based on a limited sample size. In addition, we found evidence of a chiru population decrease probably related to the human settings at the QTP during the middle Holocene.