Diversity and evolution of MicroRNA gene clusters

microRNA (miRNA) gene clusters are a group of miRNA genes clustered within a proximal distance on a chromosome. Although a large number of miRNA clusters have been uncovered in animal and plant genomes, the functional consequences of this arrangement are

乙醛脱氢酶2( ALDH2) 基因研究进展及其与饮酒行为的关系

:亚洲人群中普遍存在突变型的乙醛脱氢酶2 ( ALDH2 3 2) 。此酶突变后活性缺失,导致乙醛在肝脏内大量 累积使突变携带者在喝酒后会有脸红等不适反应,因此这可能影响他们的饮酒行为。由于ALDH2 3 2 等位基因 与饮酒行为相关,它也可能与酒精引起的肝脏损伤及某些癌症密切相关,而且,它在不同的亚洲人群中有不同的频 率分布。近年来对ALDH2 3 2 等位基因的序列结构、表达及其重要功能等有了更深入的了解,对ALDH2 的多态 性在研究方法、研究群体分布范围等都有很大进展。同时还讨论了不同地理分布、不同年龄结构、性别差异条件 下,中国人群中ALDH2 基因型频率与饮酒行为的关系。

测定细胞存活和增殖的MTT方法的建立

以Raji细胞为对象, 比较了12种不同的MTT甲ti溶解缓冲液。结果表明, 20%SDS-50%DMF效果最好, 溶解力强, 溶解甲ti所需时间短, 背景低, OD值高, 不会引起培养基中小牛血清的絮状沉淀。其溶解的甲ti产物吸收峰在550—600nm之间。测定细胞范围为每孔500—400 000, 能满足生物学和医学研究中多种测定的需要。图3表1参12

The Genomes of Oryza sativa: A history of duplications

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped superscaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000 - 40,000. Only 2% - 3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism ( SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family.

杜泊绵羊冷冻胚胎移植

介绍了从新西兰引进的冷冻杜泊羊胚胎解冻后移植到同期发情湖羊和小尾寒羊母羊受体的方法步骤,并分析、评价了胚胎移植的效果。结果表明:受体羊总平均同期发情率为78.4%,胚胎移植利用率达49.1%,妊娠率达59.4%,产羔率达58.0%,羔羊出生重为4.7 kg(公)和4.3 kg(母),羔羊1月龄和3月龄体重分别为14.9kg和32.4 kg;不同批次和不同品种受体间胚移效果亦存在不同程度的差异;4批次试验共移植冷冻胚胎475枚,产羔266只,现存活245只。该研究建立了可靠而有效的杜泊绵羊冷冻胚胎移植技术,有望在畜牧业科研和生产中广泛推广应用。

The stripe-backed weasel Mustela strigidorsa: taxonomy, ecology, distribution and status

1. The stripe-backed weasel Mustela strigidorsa is one of the rarest and least-known mustelids in the world. Its phylogenetic relationships with other Mustela species remain controversial, though several unique morphological features distinguish it from congeners. 2. It probably lives mainly in evergreen forests in hills and mountains, but has also been recorded from plains forest, dense scrub, secondary forest, grassland and farmland. Known sites range in altitude from 90 m to 2500 m. Data are insufficient to distinguish between habitat and altitudes which support populations, and those where only dispersing animals may occur. 3. It has been confirmed from many localities in north-east India, north and central Myanmar, south China, north Thailand, north and central Laos, and north and central Vietnam. Given the limited survey effort, the number of recent records shows that the species is not as rare as hitherto believed. Neither specific nor urgent conservation needs are apparent.

云南阔头蝽属二新种(半翅目: 蝽科)

记述了采自云南南部和西部的阔头蝽属二新种, 其一, 三带阔头蝽Acesines trifasciatus与A. laticeps近似, 但雄性外生殖器有显著区别。其二, 三齿阔头蝽A. tridentatus与 A. trifasciatus近似, 但体大, 色浅, 雄虫外生殖器明显区别。模式标本第一作者单位。

温度对烟蚜茧蜂发育、生殖的影响

烟蚜茧蜂发育速率与温度的关系符合逻辑斯蒂曲线,即25℃从卵至羽化所需历期最短(10.67d),30℃发育历期稍有延长(11.6d)。卵至羽化的发育起点温度为3.3℃,有效积温为266.0日度。烟蚜茧蜂雌蜂羽化当天即可产卵,在产卵期的前4天产出总卵量的90%(15-30℃);在6:30-22:30产出总卵量的80%。温度>25℃对烟蚜茧蜂雌蜂的寿命、生殖力,以及对僵蚜体重和羽化率均造成显著的负影响。烟蚜茧蜂雌蜂的寿命、性比、生殖力及僵蚜的体重和羽化率均在20℃时达最佳,结合发育历期的结果,认为该蜂大规模人工繁殖和释放的最佳温度范围是20-25℃。就研究结果在生物防治中的应用也进行了讨论。