Effects of MEK inhibitor U0126 on meiotic progression in mouse oocytes： microtuble organization, asymmetric division and metaphase Ⅱ arrest

In this study we used U0126, a potent and specific inhibitor of MEK, to study the roles of MEK/ERK/p90~(rsk) signaling pathway in the meiotic cell cycle of mouse oocytes. The phosphorylation of MAP kinase and p90~(rsk) in the oocytes treated with 1.5 μM U0126 was the same as that in oocytes cultured in drug-free medium. With 1.5 μM U0126 treatment, the spindles appeared normal as they formed in oocytes, but failed to maintain its structure. Instead, the spindle lost one pole or elongated extraordinarily. After further culture, some oocytes extruded gigantic polar bodies (>30 μm) that later divided into two small ones. Some oocytes underwent symmetric division and produced two equal-size daughter cells in which normal spindles formed. In oocytes with different division patterns, MAP kinase was normally phosphorylated. When the concentration of U0126 was increased to 15 mM, the phosphorylation of both MAPK and p90~(rsk) were inhibited, while symmetric division was decreased. When incubating in medium c     

Gene expression profile favoring phenotypic reversion: a clue for mechanism of tumor suppression by NF-IL6 3'UTR

Transfection of cDNA in 3'untranslated region of human nuclear factor for interleukin-6 (NF-IL6 3'UTR) induced tumor suppression in a human hepatoma cell line. cDNA array analysis was used to reveal changes in gene expression profile leading to tumor suppression The results indicate that this suppression was not due to activation of dsRNA-dependent protein kinase, nor to inactivation of oncogenes; rather, all the changes in expression of known genes, induced by NF-IL6 3'UTR cDNA may be ascribed to the suppression of cellular malignancy. Therefore, our results imply that this 3'untranslated region may have played role of a regulator of gene expression profile.     

LKB1及其生物学功能

LKB1基因是一种保守的抑癌基因,其编码产物LKB1即丝氨酸-苏氨酸激酶11(serine/threonine kinase,STK11)。LKB1与细胞极性调节、男性精子形成、肿瘤及细胞代谢等方面有关。本文阐述了近年来LKB1的最新研究进展。     

昆虫激肽的生理功能及机制

昆虫激肽是一类高度保守的小分子神经活性物质,自其从马德拉蟑螂脑中分离得到至今,人们在多种无脊椎动物体内均发现了这一激肽家族成员。它们具有促进昆虫后肠收缩、马氏管扭动、原尿分泌,调节血淋巴量和水盐平衡,使马氏管跨膜电位去极化,抑制昆虫体内消化酶释放、幼虫体重增长等功能。然而,天然的昆虫激肽很容易被蛋白酶所降解,因此须对其进行结构改造及构效关系研究,以开发出更有潜力的假肽和非肽模拟抗酶解昆虫激肽类似物,对今后实现环境友好型害虫防治策略具有重要意义。     

辽宁碱蓬胆碱单加氧酶基因克隆及转基因烟草的耐盐性

甜菜碱是生物体内普遍存在的一种很有效的渗透调节剂。在高等植物中,甜菜碱由胆碱经两步酶催氧化得到,即：胆碱→甜菜碱醛→甜菜碱,催化第一步反应的酶是胆碱单加氧酶（choline monooxygenase,CMO)。用RT-PCR和RACE技术从盐生植物辽宁碱蓬（Suaeda liaotungensis Kitag)中分离了CMOcDNA全序列,其中包括5′端非编码区123bp,3′端非编码区368bp。开放阅读框1329bp,编码一个由442个氨基酸构成的多肽,与菠菜,甜菜和山菠菜CMO的氨基酸序列同源性分别为77%,72%和74%。克隆了其编码区。构建了植物表达载体pBI121-CMO。根癌土壤杆菌（Agrobacterium tumefaciens)介导转化烟草（Nictiana tabacumL.cv.89),获得卡那霉素抗性植株,PCR和Southern杂交均证明外源CMO基因已整合到烟草基因组中,转基因烟草的甜菜碱含量明显高于对照。转基因烟草膜的相对电导率明显低于对照,说明盐胁迫下转基因烟草的膜结构所受损伤小于对照。转基因烟草具有一定的耐盐性。能在含250mmol/LNaCl的培养基中正常生长。     

中国三种水韭属植物的地理分布与生境特征

水韭属（Isoetes）是水韭科中的孑遗属,分类上属拟蕨类,对研究蕨类植物的系统演化具有重要价值。由于人类活动对其水生生境的破坏,水韭属植物在我国的分布范围及其种群数量日趋减少,濒临灭绝,其中,高寒水韭(I. hypsophila)、云贵水韭(I. yunguiensis)和中华水韭(I. sinensis)已被列为国家一级重点保护野生植物。对原产中国的3种水韭的地理分布与生境特征进行调查,将为合理保护该属植物提供相关基础数据和科学依据。本文野外实地考察了原产中国的3种水韭属植物的现存种群及历史记载曾经分布但现已绝迹的水韭属植物种群(绝迹种群)所在地。在每一调查点,测定了各样点的海拔高度、水体基底状况以及水体pH值等生境特征;在现存种群所在地,分别记载了所见水生植物种类、水韭种群规模及其生长状况,并采集和鉴定了3种水韭属植物及其伴生种。调查发现3种水韭属植物种与种之间为间断分布,且具有垂直梯度差异;种内各种群之间相互隔离,各种群的个体数均偏少;现存种群所生长的水体及其水体基底的pH特性无明显差异,为酸性或中性;绝迹种群所在的原生境已遭到严重破坏,一些地点的水体pH和基底pH与以往存在水韭的时期相比已明显升高。此外,调查还发现沼泽地带的水韭种群正面临着其他水生植物的激烈竞争而处于随时灭绝的危险之中,而淡水潮间带沿岸的水韭种群因周期性的水位波动而生长良好。调查结果表明3种水韭属植物的地理分布及其生长状况与海拔、水体pH值、基底pH值以及种间竞争和水位波动密切相关。本文还讨论了保护水韭属植物的基本策略和具体措施。     

中国蟾蜍科一新属

对世界蟾蜍科动物的分类现状做了概述,并对我国原定名为鳞皮游蟾Nectophryne scalptus Liu and Hu(1973)及叶昌嫒等(1978)将其改为鳞皮厚蹼蟾Pelophryne scalptus(Frost,1985订正种名为scalpta)的海南标本做了进一步研究,与现有蟾蜍科各属、特别是与东南亚地区的几个特有属的特征做了对比研究。结果表明：原定名为鳞皮游蟾Nectophryne scalptus的海南标本应代表一个新属即小蟾属Parapelophryne gen．nov．,因此原定名为鳞皮游蟾(或鳞皮厚蹼蟾)的标本为新属的成员,即种名应改为鳞皮小蟾Parapelophryne scalpta(Liu and Hu)。     

Identification of γ_1 subunit of GABA_A receptor in rat testis

INTRODUCTIONry-Aminobutyric acid (GABA) is the predomi-nant inhibitory neurotransmitter in the vertebratecentral nervous system (CNS)[1]. Whereas outsidethe CNS, many peripheral tissues have also beenfOund to have GABAergic system[2].The mammalian sperm acrosome reaction (AR)is a modified exocytotic event that is essential to thefertilization process[3]. Two main agOnists of AR,the zona pellucida glycoprotein ZP3[4] and proges-terone[5], have been identified in the oocyte vest-me…     

Identification of up-regulated genes in human uterine leiomyoma by sup-pression subtractive hybridization

In searching for differentially expressed genes in human uterine leiomyomas (ULs), suppression sub-tractive hybridization was used to construct an UL up-regulated library, which turned out to represent 88 genes. After two rounds of screening by reverse Northern analysis, twenty genes were proved to be up-regulated, including seventeen known genes and three genes with unknown function. All these genes were firstly associated with UL. Three genes with notable difference were selected for Northern confirmation. Our results proved the authenticity of the twenty genes. One gene named Phospholipase A2 (PLA2) showed up-regulation in 4/6 of the patients and investigation of tissue distribution indicated that it had obvious expression in prostate, testis, liver, heart and skeletal muscle.     

Identification and characterization of a new member of serpin family- Hon-grES1 in rat epididymis

A full length cDNA named HongrESl was isolated and cloned by screening rat epididymis cDNA library using a mouse EST as a probe and 5'RACE followed. It contained 1590bp nucleotides and its predicted protein had 415 amino acid residues including a serpin (serine protease inhibitor) conserved domain. Tissue distribution pattern showed it was specifically expressed in adult rat epididymis; moreover, in situ hybridyza-tion indicated this gene was expressed in a limited region of the cauda epididymis near vas deference. Such kind of expression pattern sugested that HongrESl had potential function in male reproduction.