As good as they get: cells in nematode vulva development and evolution

Cells are important modules of biological systems, and many evolutionary alterations involve changes in cell determination and cell proliferation. Genetic and molecular comparisons of nematode vulva development between Caenorhabditis, Pristionchus and Oscheius indicate that although the vulva is a stable organ, cell determination and proliferation change dramatically during nematode evolution.     

松乳菇中氨基酸及其它营养素含量的测定

以秦巴山区野生松乳菇子实体为材料 ,分别对其菌盖和菌柄样品中氨基酸、粗蛋白、粗脂肪、粗纤维、总糖、灰分及微量元素的含量进行了测定。结果表明 :在所测定的 1 7种氨基酸中 ,菌盖含有 1 7种 ,菌柄含 1 6种 ,氨基酸总含量分别为 1 9.89%和 1 3 .79% ;必需氨基酸分别占氨基酸总量的 3 6.75 %和 3 5 .95 %。菌盖和菌柄中粗蛋白、粗脂肪、粗纤维、总糖、灰分含量分别为 2 4 .2 7% ,1 9.0 3 % ;6.84 % ,5 .0 2 % ;1 1 .5 2 % ,1 5 .2 6% ;3 7.4 1 % ,2 3 .89%和 7.4 2 % ,5 .2 8%。钙、铁、锌、铜、锰 5种微量元素中 ,铁含量最高 ,在菌盖和菌柄样品中分别为 0 .1 68% ,0 .1 2 %     

Xterra RP18柱高效液相色谱法快速分离测定氨基酸

建立了一种用XterraRP1 8色谱柱快速分离测定水解氨基酸的方法。所采用的色谱条件是 :WatersAlliance系统 ,柱温 5 6℃ ,流速 1 .8ml/min ,检测波长 2 4 8nm ,梯度分离 ,运行周期 2 5min,柱反压低于 2 0 0 0Psi。在 1 7.5min内分离了包括AMQ、NH3 和牛磺酸在内的 2 1种氨基化合物 ,适应于复合氨基酸注射液、含牛磺酸的氨基酸口服液及水解氨基酸样品的分析测定     

黑米皮花青苷色素测定方法的研究

以五种黑米皮为实验材料 ,采用优化方法 ,确定了黑米花青苷类色素测定实验条件。结果表明 :黑米皮脱脂后 ,80℃、酸性乙醇 ( 1 .5mol/LHCl-95 %乙醇 =1 5 /85 )、6 0min重复提取两次 ,可实现 95 %以上的色素溶出。提取液选取 1cm比色皿、与 5 35nm波长下测定ABS值 ,计算色价 (E 1%1cm ,λ=53 5nm　　　　 ) ,作为一种黑米花青苷类色素含量测定方法 ,可用于黑米品质分析     

Egg-laying, pre-imaginal growth dynamics, and mortality in Eupelmus orientalis and Dinarmus basalis, two solitary ectoparasitoids of Callosobruchus maculatus

In Eupelmus orientalis and Dinarmus basalis, two ectoparasitoid species of Callosobruchus maculatus larvae, pre-imaginal development occurs within a leguminous seed, and is then impossible to observe directly. Offspring sex ratio is normally determined when adults emerge, and mortality during pre-imaginal stages remains unknown. By using translucent gelatine capsules containing a host larva to mimic the seed, we conducted an experimental study of offspring production and sex ratio with measurements of growth and pre-imaginal mortality. Mated females were allowed to lay eggs on hosts in seeds or in gelatine capsules. In the gelatine capsules the parasitoid was observed daily and measured to assess if the offspring sex ratio can be determined before emergence of adults. When seeds are replaced with gelatine caps, the number of egg-laying females decreases (48% in Eupelmus orientalis and 72% in Dinarmus basalis of females ovipositing on seeds lay eggs on gelatine capsules), and the offspring output changes qualitatively in Eupelmus orientalis (egg numbers constant, sex ratio diminishing from 0.75 to 0.46) and quantitatively in Dinarmus basalis (egg numbers diminishing, sex ratio maintained about 0.7). In Eupelmus orientalis, pre-imaginal mortality occurs principally in the first three days, the critical stage is hatching, and the final mortality is 30.1%. In Dinarmus basalis, mortality of larvae increases gradually from the 2nd to the 7th day, the final mortality being 13.6%. (3) In both species sex of the offspring can be determined before emergence but only after most mortality has occurred.     

爬行动物胚胎的行为热调节

行为热调节是外温动物体温调节的主要方式。传统观点认为行为热调节仅存在于胚后阶段,然而近年来研究表明爬行动物胚胎具备行为热调节能力。本文回顾了爬行动物胚胎行为热调节的发现和研究进展,探讨了胚胎行为热调节的生态适应意义,分析了胚胎如何感知温度以完成行为热调节,指出了该领域的未来研究方向。     

Mechanisms of sex determination and X-chromosome dosage compensation

Abnormalities in chromosome number have the potential to disrupt the balance of gene expression and thereby decrease organismal fitness and viability. Such abnormalities occur in most solid tumors and also cause severe developmental defects and spontaneous abortions. In contrast to the imbalances in chromosome dose that cause pathologies, the difference in X-chromosome dose used to determine sexual fate across diverse species is well tolerated. Dosage compensation mechanisms have evolved in such species to balance X-chromosome gene expression between the sexes, allowing them to tolerate the difference in X-chromosome dose. This review analyzes the chromosome counting mechanism that tallies X-chromosome number to determine sex (XO male and XX hermaphrodite) in the nematode Caenorhabditis elegans and the associated dosage compensation mechanism that balances X-chromosome gene expression between the sexes. Dissecting the molecular mechanisms underlying X-chromosome counting has revealed how small quantitative differences in intracellular signals can be translated into dramatically different fates. Dissecting the process of X-chromosome dosage compensation has revealed the interplay between chromatin modification and chromosome structure in regulating gene expression over vast chromosomal territories.     

拟南芥GLABROUS1两个新等位突变体的筛选和鉴定

植物细胞命运决定机制的解析一直以来都是植物发育生物学研究的核心.模式植物拟南芥的表皮毛形成过程是研究植物细胞命运决定的优良模式系统.为了筛选和鉴定控制拟南芥表皮毛形成的新因子,我们进行了大规模的正向遗传筛选,获得了两株莲座叶表皮毛不能形成或数量显著减少的突变体f08-01和vat002-07.通过对突变基因的克隆和遗传...     

温度对黄喉拟水龟性别决定的影响

研究了不同孵育温度对黄喉拟水龟(MauremysmuticaCantor)性别决定的影响,同时分析了孵育温度对胚胎发育及成活率的影响。实验设置的3个孵化温度为(25±0.5)℃,(29±0.5)℃和(33±0.5)℃。每一温度指标下设置40枚受精卵。在实验温度内,胚胎的发育速度随着孵化温度的升高而加快,所用的孵育时间也越来越短。孵化累积温度CTUs在25℃时最高,在29℃时最低,而33℃时则居中,在25℃和29℃时,孵化成活率较高,均达到97.5%。在33℃时孵化成活率只有67.5%,而在孵出的稚龟中亦有一定数量的畸形龟,累积孵化温度也高于29℃时的CTUs,说明33℃的孵育温度对胚胎发育有不利影响,预示33℃已临近其胚胎发育的存活阈(Survivalthreshold)。在25℃时,雄性子代占优势,雌性率为23.7%;在33℃时,雌性子代占绝对优势,雌性率为94.7%;在29℃时,性比达到平衡,雌性率为50%。经X2检验,在25℃及33℃时的性比与依赖概率估计的性比(1∶1)有极显著的差异(p<0.005),这种显著的偏离说明黄喉拟水龟的性别决定属于TSD机制,而且可能属于其中的TSDⅠ型,即高温产生雌性子代,低温产生雄性子代。而29℃可能是黄喉拟水龟性别决定的临界温度。     

Quantitation of proteins on Coomassie blue-stained polyacrylamide gels based on spectrophotometric determination of electroeluted dye

A procedure for quantitating proteins on Coomassie blue-stained polyacrylamide gels is presented. The method is based on the observations that the dye is rapidly eluted electrophoretically from stained protein bands or spots in the presence of sodium dodecyl sulfate, and that the eluted dye is nondialyzable. Protein may therefore be assayed indirectly by measuring the dye in electroeluents spectrophotometrically. Moreover, the stain elutes more rapidly than the protein, allowing separate recovery of the protein for further analysis. The assay is independent of band or spot size, and does not involve physical disruption of the gel piece or any chemical treatment harsher than the staining process itself. The technique has been applied to the contractile proteins myosin, actin, and commercially obtained standards resolved by one-dimensional electrophoresis, and to proteins in nuclear extracts of HeLa cells on two-dimensional gels.