Protein and nuclear changes in pig eggs at fertilization.

The nuclear restructuring that occurs between insemination and full pronuclear formation in pig eggs is accompanied by posttranslational changes to specific egg proteins. Sperm penetration begins in vitro at 3 hr postinsemination (hpi). By 5 hr, decondensing sperm heads and anaphase II plates are observed in 50% of eggs, and, by 8 hpi, both male and female pronuclei have formed. Three consistent changes to the pattern of newly synthesised proteins are triggered in this period; they affect the 46K, 25K, and 22K polypeptides. Changes are also triggered in the 180-200K polypeptides and in the 14K polypeptides, but these are highly variable. The same changes in the prefertilization pattern were observed when prelabelled eggs were used and new protein synthesis was suppressed. The first and most abrupt change involves the apparent catabolic elimination of a group of 46K unphosphorylated polypeptides (pl 7.3-6.4), whose synthesis was greatest before germinal vesicle breakdown but declined slowly in the final phase of maturation, then declined precipitously after activation. Ageing (beyond maturation) also leads to the disappearance of these polypeptides. The progressive disappearance of a set of 25K polypeptides and the concomitant appearance of a dominant 22K polypeptide is the most characteristic fertilization-induced modification to porcine egg proteins. These modifications begin within 1 hr of sperm penetration or activation, are specific to the pig, and involve heavily phosphorylated polypeptides (25K, pl 6.7-6.0) whose synthesis is begun in the early metaphase I stage. Dual ([35S] and [32P]) labelling, protein blocking experiments, and use of alkaline phosphatase suggest that dephosphorylation selectively affects these 25K polypeptides and is mainly or wholly responsible for converting them (completely within 6 hr) to a single, new (22K, pl 7.6) species that is positively charged. The 25K/22K polypeptide modification has a close temporal relationship with the formation of the male and female pronuclei.     

Evidence of synergy between Thy-1 and CD3/TCR complex in signal delivery to murine thymocytes for cell death.

The potential role of Thy-1 in CD3/TCR complex-mediated signal delivery to murine thymocytes was studied. Ag-mimicking cross-linked anti-CD3 mAb stimulated suspension of thymocytes from adult (6 to 8 wk old) mice for a brisk free cytoplasmic calcium ion ([Ca2+]i) rise, low level of inositol phosphate production, and marginal increase in tyrosine-specific phosphorylation of 110/120-kDa and 40-kDa cellular proteins. Weak but sustained [Ca2+]i rise, low inositol phosphate production, and weak protein tyrosine phosphorylation were also induced by the cross-linked anti-Thy-1 mAb that mimicked the putative natural ligand. The signal delivered via either of these two pathways was however insufficient for definitively promoting cell death and DNA fragmentation in the adult thymocytes. Here we demonstrated that anti-Thy-1 mAb synergized with anti-CD3 mAb for inducing a long-lasting prominent [Ca2+]i rise, definite inositol 1,4,5-triphosphate and inositol 1,3,4,5-tetrakiphosphate production, and extensive tyrosine-specific phosphorylation of 110/120-, 92-, 75-, and 40-kDa proteins, which resulted in marked promotion of cell death and DNA fragmentation in the adult thymocytes. This unique anti-Thy-1 antibody activity was confirmed to be directed to glycosylphosphatidylinositol-anchored Thy-1, and was distinguished from the known anti-L3T4 activity that augmented the CD3-mediated signal transduction in a different manner. The synergistic actions of anti-CD3 and anti-Thy-1 mAb obligatorily required the cross-linking of the two mAb together. The anti-CD3 and anti-Thy-1 mAb cross-linked together acted on immature thymocytes from newborn (less than 24 h after birth) mice for rather more extensive promotion of protein tyrosine phosphorylation and cell death. In addition, they affected peripheral T lymphocytes for accelerating protein tyrosine phosphorylation but not cell death. These results suggest a novel function of glycosylphosphatidylinositol-anchored Thy-1 as a possible unique intrathymic intensifier of the CD3/TCR complex-delivered signal for negative thymocyte selection.     

浙江省水鳖科植物的种类与分布

浙江省有水鳖科植物5属8种,均属淡水种类,其中无尾水筛、有尾水筛和密齿苦草为浙江分布新记录。在水平分布上,水筛属分布局限于浙江东南部,苦草属则分布于浙江大部分地区而未见于浙江南部。在垂直分布上,水筛属的种数和分布量,在海拔600米以下,随海拔增高而增加,再向上又有减少的趋势;其余各属的种数和分布量则随海拔增高而减少。它们的分布主要受各自适宜的生境在水平和垂直带的不同分布所制约。浙江水鳖科植物区系与我国亚热带各省区尤其是相邻省的关系十分密切。     

“雄茭”、灰茭形成规律的初步研究

茭白栽培过程中,常会出现“雄茭”和灰茭分蘖。根据对茭白的形态学观察,认识到:“雄茭”分蘖的产生是分蘖期母茎中茭白黑粉菌菌丝未能入侵新生分蘖腋芽而导致的结果;灰茭分蘖是因其菌丝的潜育期比正常茭短,故在苗端的膨大部分较早地产生了不同程度的黑粉孢子堆。     

辽宁省丹东地区吸血蠓类(双翅目:蠓科)生态调查

吸血蠓类对人畜危害较大,不仅是多种疾病的传播媒介,而且刺叮吸血骚扰性很大。1988年我们在辽宁省丹东地区东沟和风城二县郊区进行了采集和生态习性的调查,现将结果报道如下。材料和方法器材由军事医学科学院微生物流行病研究所提供的诱蠓帐、捕虫网和吸虫器。调查方法     

草鱼出血病病毒对其它鱼的感染性研究

用草鱼出血病病鱼分离出的草鱼出血病病毒(Grass carp hemorrhage virus,GCHV)感染其它常见鱼并用ELISA方法检查感染鱼组织提取液,结果表明:青鱼、鲢鱼、布氏鳌条对GCHV抗体呈阳性反应;鲤鱼、鳙鱼、鲫鱼、团头鲂、泥鳅则呈阴性反应。综合感染鱼发病症状及死亡特征,初步认为:青鱼对GCHV是易感的,GCHV能在鲢鱼、布氏蟹条体内增值,但毒力较低,鳙鱼、鲫鱼、团头鲂、鲤鱼、泥鳅能抗GCHV感染。     

江苏菜豆同工凝集素的分离纯化及性质研究

江苏菜豆经酸水(PH2.0)抽提,硫酸铵分级沉淀,分离植物血球凝集素(PHA-P),分子量为128000的糖蛋白,活性回收率在80％以上,PHA-P经SP-sephadexc-50离子交换层析,分成L_4,L_3E_1,L_2E_2,L_1E_3,和E_4同工凝集素。 L_4和E_4等电点为5.4和6.5。亚基分子量分别是31000和33000,并有类似的氨基酸组成。PAGE分析为单一蛋白带。红细胞凝集活性随电泳迁移速度的加快而增强,促淋性细胞分裂活性则减弱。E_4血凝活性受CalNAc,EDTA抑制和Zn~(++)的促进。     

Prostaglandin production in the umbilical and uterine circulations in pregnant sheep at 129-136 days gestation.

Prostaglandins circulating in the maternal and foetal blood have been implicated in important physiological systems. These functions include foetal adrenal function, maintenance of patency of the ductus arteriosus, regulation of uterine and umbilical circulations, and labor and delivery type myometrial contractions. The placenta is a major site of prostaglandin production in pregnancy. Limited data are available which combine measurements of veno-arterial differences across the uterine and umbilical circulations with blood flow in these circulations to enable calculation of umbilical-placental and utero-placental production rates for the prostaglandins. In chronically instrumented pregnant ewes, between 129 and 136 days of gestation, prostaglandin F2 alpha(PGF2 alpha), 13, 14 dihydro-15-keto prostaglandin F2 alpha (PGFM), prostaglandin E2 (PGE2) were measured in the maternal carotid artery and uterine vein. Foetal PGE2, and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) (the major metabolite of prostacyclin) were measured in umbilical venous and foetal descending aorta arterial plasma. Umbilical and uterine blood flow were measured using the diffusion-equilibrium technique. Uterine blood flow was 1693 +/- 137 ml.min-1 (mean +/- SEM); uterine production rates were 480 +/- 88 ng.min-1 for PGF2 alpha, 517 +/- 144 ng.min-1 for PGFM, and 165 +/- 27 ng.min-1 for PGE2. Umbilical blood flow was 147 +/- 17 ml.min-1.kg-1 foetal body weight. Umbilical production rates into the foetal circulation were 11 +/- 2 ng.min-1.kg-1 for PGE2 and 6 +/- 2 ng. ng.min-1.kg-1 foetal body weight for PGI2.     

Cloning, expression, and characterization of the Escherichia coli K-12 rfaD gene.

The rfaD gene encodes ADP-L-glycero-D-mannoheptose-6-epimerase, an enzyme required for the biosynthesis of the lipopolysaccharide precursor ADP-L-glycerol-D-mannoheptose. The precise localization of the rfaD gene on a 1.3-kilobase SspI-HpaI fragment is reported. The rfaD gene and the flanking regions were completely sequenced. The location of the rfaD gene on the physical map of the Escherichia coli chromosome was determined. Primer extension studies were used to define the regulatory region of the rfaD gene. The cloned rfaD gene directed the synthesis of a 37,000-dalton polypeptide in several in vivo and in vitro expression systems. N-terminal analysis of purified ADP-L-glycero-D-mannoheptose-6-epimerase confirmed the first 34-amino-acid sequence deduced from the nucleotide sequence of the rfaD gene coding region. The primary structure of the rfaD protein contains the sequence fingerprint for the ADP-binding beta alpha beta fold at the N terminus.