汞的生物毒性及其防治策略

汞是一种剧毒环境污染物。汞与生物大分子上的活性点结合,使其失去活性,导致病变。     

Maternal vitamin A restriction alters biochemical development of the brain in rats

Summary The biochemical development of the fetal brain in relation to maternal vitamin A restriction was studied in rats. The vitamin A status of pregnant rats was varied by supplying low, medium and adequate amounts (6, 40, and 100 g retinol/day/kg body weight, respectively) of vitamin A during pregnancy and suckling. The maternal vitamin A restriction caused an altered brain development in terms of tissue weight, DNA, RNA and protein levels, and biosynthesis of DNA and protein from [³H]-thymidine and [³H]-leucine, respectively. A dose-dependent effect of maternal vitamin A restriction on the metabolism of DNA, RNA and protein was noticed in the developing fetal brain of rats.     

人类基因ZNF569结构域在MAPK信号途径中的作用

有丝分裂原活化蛋白激酶（MAPK）信号途径是细胞信号转导过程的重要组成部分，MAPK将膜转导蛋白与其细胞内的关键调控靶蛋白联系起来，从而介导胞外的多种信号并将这些信号级联放大后传递给相应的下游因子，通过激活包括SRE，ELK-1，AP-1等在内的多种转录因子，最终开启细胞特定功能基因的表达，锌指蛋白是人类最大的基因家族之一，其蛋白产物主要通过与DNA相互作用而起转录因子作用，调节靶基因的表达以适应生物体发育、分化、成熟过程的需要，运用MAPK信号途径对锌指基因ZNF569的结构域进行了转录活性分析，分析表明在COS-7细胞中过表达ZNF569蛋白可以使MAPK信号途径的两个下游转录因子AP-1和SRE的转录抑制活性显著下降，ZNF569在核质内的亚细胞定位分析进一步证明了其作为转录因子的作用，对ZNF569的分段report assays分析表明，ZNF569可能通过KRAB框和C2H2锌指结构域行使其抑制转录的作用，这些结果表明，ZNF569可以通过MAPK信号途径参与了对细胞生命活动的调控过程。     

畜禽血液甲状腺激素及其载体蛋白的研究进展

本文综述了近年来有关畜禽血液甲状腺激素及其载体蛋白的研究现状,就其检测原理、方法进行了分析,阐明了该研究的理论意义和广阔的应用前景,为畜禽育种工作提供了科学依据.     

杨树叶对鸡日粮中蛋白质和脂肪利用率的影响

研究了杨树叶对滨白蛋鸡蛋白质利用率和脂肪利用率的影响,结果表明:20%杨树叶可使滨白蛋鸡对日粮中蛋白质利用率提高7.80%,对日粮中脂肪利用率提高3.96% .用杨树叶干粉部分替代蛋鸡日粮可提高蛋鸡对蛋白质、脂肪等营养物质的利用率.     

细菌脂多糖中GDP-colitose糖合成基因的预测、克隆及表达鉴定

colitose糖存在Salmonella enterica O50、S.enterica O35、E.coli O111、E.coli O55和Vibrio choleraeO139等少数几种细菌的O-抗原中.GDP-colitose糖的合成酶基因分别为wbdJ、wbdK和gmd.用PCR的方法扩增出三种基因的片断,克隆到表达载体pCAL-c中,从而构建了表达质粒pLW1、pLW4、pLW7,转化到大肠杆菌BL21-Gold中,获得工程菌株B10,B11,B12.IPTG诱导表达,纯化得到三种电泳纯的表达产物,分子量分别约为35kD,44kD,42kD,与预测结果相似.     

实验性交感性眼炎发病机制的研究

以13只白色豚鼠作实验,其中3只为 C 组作对照,另10只分为 A、B 二个组,在以牛晶体蛋白连续皮内注射4次致敏之后,做一只眼的晶体截囊术。术后 A 组皮下注射生理盐水,B 组则皮下注射环孢霉素(Cyclosporine)。结果 A 组发生交感性眼炎,而 B 组和 C 组均未发生。因为环孢霉素具有选择性的抑制 T 淋巴细胞的功能,故推测交感性眼炎的发病机制可能与 T 淋巴细胞的关系极为密切。     

Structure and function of a calmodulin-dependent smooth muscle myosin light chain kinase

Summary In smooth muscle the M_r 20,000 light chain of myosin is phosphorylated by a calmodulin-dependent protein kinase. It consists of 2 subunits: calmodulin, an acidic protein of M_r 17,000 that binds 4 moles of Ca²⁺; and a larger protein of M_r circa 130,000. Activation of the kinase is dependent upon their association in the presence of Ca²⁺. Cyclic AMP-dependent protein kinase phosphorylation of the myosin light chain kinase occurs at 2 sites. It decreases the affinity of the kinase for calmodulin and a reduction in the rate of light chain phosphorylation occurs. The kinase has an overall asymmetric shape composed of a globular head and tail region for the skeletal muscle enzyme. Trypsin digestion of this kinase releases a fragment of M_r 36,000 from the globular region that contains the catalytic and calmodulin binding sites. Chymotrypsin digestion of the kinase from smooth muscle generates a fragment of M_r 80,000 that does not contain the calmodulin binding or cyclic AMP-dependent protein kinase phosphorylation sites. It is a Ca²⁺-independent form of the kinase that phosphorylates the light chain of myosin. These structural features indicate a regulatory role for the kinase in smooth muscle phosphorylation and contraction.     

The oak processionary caterpillar (Thaumetopoea processionea L.) an urticating caterpillar related to the pine processionary caterpillar (Thaumetopoea pityocampa Schiff.) (Lepidoptera,Thaumetopoeidae)

Summary The hairs ofThaumetopoea processionea caterpillars (Lepidoptera) provoke a cutaneous reaction in man and animals. The urticating apparatus, the urticating gland which produces hairs, and the urticating hairs, are similar to those of theT. pityocampa caterpillar. The irritant fraction extracted from hairs contains soluble proteins; one of these shows immunological identity with thaumetopoein, the urticating protein of theTh. pityocampa caterpillar. This thaumetopoein-like protein is currently undergoing isolation and will be subjected to dermatological tests.     

The phorbol ester TPA induces metamorphosis in Red Sea coral planulae (Cnidaria: Anthozoa)

Controlled experiments on the metamorphosis of marine invertebrate larvae require artificial inducers. These inducers can be used for studying the involvement of known signal transduction pathways in settlement and metamorphosis. The ability of the tumor-promoting phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) to induce metamorphosis in planulae of the Red Sea soft coral speciesHeteroxenia fuscescens, Xenia umbellata, Dendronephthya hemprichii, Litophyton arboreum andParerythropodium fulvum fulvum, and the stony coralStylophora pistillata, was examined by using various concentrations of TPA. The chemical induced metamorphosis in all six species. The effect was unspecific and concentration-related. For all the corals except forX. umbellata the highest mean percentages of metamorphosis were obtained with 8.1×10^–7–10^–9 M TPA. ForX. umbellata, the percentage of metamorphosis was lower, and was obtained within a wider TPA concentration range. The present results, along with previous studies on Hydrozoa and Scyphozoa, demonstrate that TPA is the first common artificial inducer for these classes of Cnidaria. TPA is known to activate the enzyme protein kinase C (PKC) and therefore plays an important role in studying the phosphatidylinositol signal transduction system. Evidence for the involvement of this pathway in triggering metamorphosis has already been reported for Hydrozoa and Scyphozoa. Our results suggest that PKC is also involved in initiating metamorphosis in Anthozoa.