Cdc42蛋白在牛卵母细胞中的表达分布及对其成熟的影响

【目的】探明Cdc42蛋白在牛卵母细胞成熟过程中的表达及分布规律,并且研究抑制Cdc42活性对于牛卵母细胞成熟的影响。【方法】首先通过收集体外成熟不同时间（0-24 h）的牛卵母细胞,用Western blotting的方法检测Cdc42蛋白在牛卵母细胞中的表达量变化情况,通过免疫细胞化学的方法检测Cdc42蛋白在牛卵母细胞中的分布及定位情况。根据GenBank公布的牛Cdc42基因（GenBank登录号：NM_001046332.1）的mRNA序列设计引物,并在正向和反向引物的末端分别加上KpnⅠ和EcoRⅠ酶切位点,用PCR的方法扩增牛Cdc42基因的CDS区,将PCR产物和pMD19T载体连接得到野生型的克隆载体pMD19T-Cdc42WT。用定点突变引物以pMD19T-Cdc42WT为模板进行PCR反应,得到Cdc42的显性负性突变体Cdc42T17N的克隆载体pMD19T-Cdc42T17N。将pMD19T-Cdc42WT和pMD19T-Cdc42T17N分别酶切后,将Cdc42WT（775 bp）和Cdc42T17N（775 bp）片段分别连接到pcDNA3.1（+）的多克隆位点区域,得到相应的原核表达载体pcDNA3.1（+）-Cdc42WT和pcDNA3.1（+）-Cdc42T17N。用体外转录的方法分别得到Cdc42WT和Cdc42T17N的cRNA,用显微注射的方法将相应的cRNA分别注入到牛GV期卵母细胞质内,检测其成熟率的变化。【结果】①Cdc42蛋白分别在牛卵母细胞中成熟培养0、4、8、12、16、20以及24 h时表达量没有明显差异,但是其分布规律随着减数分裂的进行发生着动态的变化：Cdc42蛋白在卵母细胞皮质区域集中分布的模式在生发泡（germinal vesicle,GV）期卵母细胞中很少出现,而在第一次减数分裂中期（metaphase Ⅰ,MⅠ）卵母细胞中出现得最多也最为明显;Cdc42蛋白在染色体附近的皮质富集的现象开始出现于前中期（pro-metaphase Ⅰ,pMⅠ）,并且出现频率从pMⅠ期到第2次减数分裂中期（metaphase Ⅱ,MⅡ）逐渐增多;Cdc42蛋白和纺锤体重叠定位的现象在第1次减数分裂后期（anaphase Ⅰ,AⅠ）到末期（telophaseⅠ,TⅠ）的卵母细胞中占有有很高比例,而到MⅡ期时这种现象又很少出现。②从牛卵母细胞的总cDNA中扩增Cdc42基因得到785 bp的片段,构建的牛Cdc42的野生型及其显性负性突变体的克隆载体pMD19T-Cdc42WT和pMD19T-Cdc42T17N经酶切鉴定和以及测序比对后,符合预期结果,即成功克隆了牛野生型Cdc42基因并得到其显性负性突变体Cdc42T17N;③构建的相应的原核表达载体pcDNA3.1（+）-Cdc42WT和pcDNA3.1（+）-Cdc42T17N经酶切鉴定和测序比对,符合预期结果,经过体外转录均得到一个3079 bases和987 bases的RNA片段,符合预期结果,即成功构建了相应的原核表达载体并获得相应的cRNA;④与正常成熟培养组和注射Cdc42WTcRNA的牛卵母细胞相比,注射Cdc42T17NcRNA的成熟率显著降低（P<0.05）。【结论】卵母细胞在卵泡发育过程中就已经积累了足够的Cdc42蛋白,而在减数分裂过程中Cdc42可以在卵母细胞的皮质以及纺锤体的位置发挥作用,而且正常的Cdc42活性是牛卵母细胞完成成熟过程并排出第一极体所必需的。     

Induction by NGF of meiotic maturation of Xenopus oocytes expressing the trk proto-oncogene product.

The effect of nerve growth factor (NGF) was assessed in Xenopus oocytes expressing the human trk proto-oncogene product, p140prototrk. Oocytes injected with trk messenger RNA expressed polypeptides recognized by antibodies to the trk gene product. Exposure of these oocytes to nanomolar amounts of NGF resulted in specific surface binding of 125I-labeled NGF, tyrosine phosphorylation of p140prototrk, and meiotic maturation, as determined by germinal vesicle breakdown and maturation promoting factor (p34cdc2) kinase activation. Thus the trk proto-oncogene product can act as a receptor for NGF in a functionally productive manner.     

IGF—II生理功能及其编码基因的结构研究

IGF-II属于胰岛素样生长因子家族中的重要成员,在哺乳动物的生长发育过程中发挥着重要的作用。本文从IGF-II生理功能,IGFs受体和结合蛋白,IGF-II蛋白及IGF-II基因结构,IGF-II基因表达和IGF-II基因印迹等方面进行了综述。     

Potassium salt microinjection into Xenopus oocytes mimics gonadotropin treatment

Gonadotropin stimulates protein synthesis and growth in ovarian oocytes. The hormone is also known to modify transfollicular K+ fluxes and is now shown to cause increased intraoocytic K+ activity (aK). The hormone's effect on aK was duplicated by microinjecting K+ salts into oocytes which were incubated in paraffin oil. This treatment mimicked the influence of gonadotropin on both the rate of protein synthesis and the synthesis of specific polypeptides. These findings suggest that gonadotropin-stimulated oocyte growth is attributable largely to the hormone's influence on transfollicular K+ fluxes. They support the hypothesis that the K+ flux and aK changes observed during cell activation are critical in causing subsequent increases in protein synthesis and growth.     

生长分化因子9在兔卵巢中的免疫组织化学定位

［目的］探讨生长分化因子9（GDF9）在兔卵巢卵泡发生过程中的调控机制。［方法］采用免疫组织化学方法测定GDF9蛋白在兔卵巢中的表达定位情况。［结果］GDF9在原始卵泡中没有表达;在初级卵泡、次级卵泡和有腔卵泡卵母细胞及有腔卵泡颗粒细胞、透明带及卵泡液中均检测到GDF9蛋白;在黄体中也有GDF9的表达。［结论］GDF9不仅是卵母细胞分泌因子,而且是颗粒细胞的分泌因子,其表达随兔卵巢中卵泡发生呈时空动态变化,在兔卵巢卵泡发生过程中发挥了重要作用,参与了黄体活动的调节。     

Activin-binding protein from rat ovary is follistatin

Activin, a member of the transforming growth factor beta protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH). Activin has numerous functions in both normal and neoplastic cells. Various cells synthesize activin and have a specific binding site for this peptide. However, the molecular basis for its actions is unknown. A binding protein for activin was purified from rat ovary and was identical to follistatin, a specific inhibitor of FSH release. It is likely that the binding protein participates in the diverse regulatory actions of activin.     

EGF在哺乳动物卵母细胞体外受精中的作用

[目的]为卵母细胞的生长发育创造更加适宜的环境。[方法]对EGF的理化特性、作用机理及其在卵母细胞体外培养、体外受精和早期胚胎发育中的作用进行阐述。[结果]EGF、IGF和TGF等生长因子在哺乳动物卵母细胞体外培养中起很重要的作用,尤其是在无血清培养条件下。生长因子可大大提高卵母细胞的成熟率和受精率,并对受精卵的发育有很大的促进作用。在众多生长因子中研究的最多的就是EGF。EGF能够促进卵母细胞减数分裂、卵丘细胞扩散,调节卵母细胞胞质成熟。[结论]对EGF的深入研究对于提高哺乳动物卵子的体外成熟率、体外受精率以及胎儿的发育都具有重大意义,为体外受精等技术和胚胎工程的发展提高可靠的保障。但对清楚了解EGF及其受体的性质和作用机制仍存在很多问题,且对表皮生长因子对体外受精的作用研究较少。     

锌指蛋白转录因子Di19参与调控大豆干旱响应的研究进展

干旱是人类面临的最主要自然灾害之一,是影响农作物生产最主要的环境因素。锌指蛋白指含有锌离子、具有手指状结构域的一类蛋白质,是植物中发现种类最多、调控作用最显著的一类转录因子,在植物干旱响应中发挥重要作用。Di19是最新发现的一类小分子锌指蛋白,其含有两个C2H2型锌指结构域,受干旱和高盐诱导,在植物的抗旱响应中起积极作用。大豆根系不发达,需水量多,对干旱敏感,水分亏缺是制约其产量提高和品质提升的最重要环境因子。本文评述了大豆耐旱性研究现状,锌指蛋白及其家族最新成员Di19在大豆耐旱性响应过程中发挥的作用,以期为大豆耐旱性改良提供参考。     

母羊妊娠后期与泌乳期对不同营养水平饲粮的消化性

采用单因素分组试验设计,用寒×滩杂种妊娠母羊(1~2胎,每组3或5只)分别测定了妊娠后期和泌乳期3个营养水平(Ⅰ组0.8×NRC,Ⅱ组0.9×NRC,Ⅲ组1.0×NRC水平)饲粮养分的表观消化率.结果表明,在妊娠后期,饲粮Ⅱ的DMD、OMD(P<0.01)和CPD、ADFD均显著地高于饲粮Ⅰ(P<0.05),ADFD极显著高于Ⅲ(P<0.01),DMD和OMD呈高于Ⅲ的趋势(P=0.182,P=0.089);饲粮Ⅲ的DMD显著高于Ⅰ(P<0.05),OMD和CPD呈现高于Ⅰ的趋势(P=0.119,P=0.054).泌乳期中,饲粮Ⅲ的DMD(P=0.011)、OMD(P=0.010)均显著高于Ⅰ,DMD和OMD呈高于Ⅱ的趋势(P=0.184,P=0.181);Ⅲ和Ⅱ的CPD也呈现高于Ⅰ的趋势(P=0.067,P=0.161);各饲粮间ADFD的差异均不显著(P>0.05).试验结果显示在不同的生理阶段母羊对饲粮的消化力存在差异.     

Hypomethylation of DNA from benign and malignant human colon neoplasms

The methylation state of DNA from human colon tissue displaying neoplastic growth was determined by means of restriction endonuclease analysis. When compared to DNA from adjacent normal tissue, DNA from both benign colon polyps and malignant carcinomas was substantially hypomethylated. With the use of probes for growth hormone, gamma-globin, alpha-chorionic gonadotropin, and gamma-crystallin, methylation changes were detected in all 23 neoplastic growths examined. Benign polyps were hypomethylated to a degree similar to that in malignant tissue. These results indicate that hypomethylation is a consistent biochemical characteristic of human colonic tumors and is an alteration in the DNA that precedes malignancy.     

Electrical responses of eggs to acrosomal protein similar to those induced by sperm

The earliest known response of eggs to sperm in many species is a change in egg membrane potential. However, for no species is it known what components of the sperm cause the opening of the egg plasma membrane channels. Protein isolated from sperm acrosomal granules of the marine worm Urechis caused electrical responses in oocytes with the same form, amplitude, and ion dependence as the fertilization potentials induced by living sperm. Sperm initiated fertilization potentials in oocytes when sperm-oocyte fusion, but not binding, was inhibited by clamping oocyte membrane potentials to positive values. Acrosomal protein also initiated electrical responses in clamped oocytes. These results support the hypothesis that it is the sperm acrosomal protein that opens ion channels in the oocyte membrane.     

Message transmission: receptor controlled adenylate cyclase system

The adenylate cyclase system is composed of an activating hormone or neurotransmitter (H), its receptor (R), the guanosine triphosphate (GTP) binding protein (Gs), and the catalytic unit (C). The activation of the receptor R involves a transient change in conformation, from a loose binding of the neurotransmitter H to an extremely tight interaction, termed locking. The system is regulated in the activation steps and also by three deactivation processes. A guanosine triphosphatase activity is built into the Gs protein so that the active GsGTP has only a limited lifetime during which it is able to activate C. In addition, the continued occupation of R by H causes desensitization of R. Finally, there are inhibitory receptors, such as alpha-adrenergic and opiate receptors, which inhibit the adenylate cyclase by way of a specific GTP binding protein (Gi). Yet to be determined are the conformational transformations of pure R on binding of an agonist or a partial agonist; the genes that code for the many different receptors that activate the adenylate cyclase, and the possibility that the G components interact with systems in the cell other than the adenylate cyclase.     

Effects of Different Protein Levels on the Growth Performance and Metabolic Rate of Nutrition in Broilers

The objective of this study is to determine the effect of different protein levels on the growth performance and metabolic rate of nutrition in broilers. Total 360 healthy and weight closed local broilers of 3 weeks were chosen and then divided into three groups randomly by one factor. Each group contains three handlings, each handling consists of 40 broilers. The period of experiment was 7 weeks. The metabolic experiment was performed at the 7th week. Three different protein levels were used in broilers＇ diet. The levels of protein were 19%, 17.5% and 16%. The results showed that the different levels of protein in crude dietary had significant difference between 19% group and the other two groups. The average daily weight gain and daily efficiency were significantly higher than that of the other two groups （P〈0.05）. Compared to protein levels of 19% and 16%, there was no significant difference in the metabolism of calcium （P〉0.05）, and the metabolic rate of the impact of phosphorus was significantly different （P〈0.05）. The result showed that when protein level was 19%, the growth of the local broiler was the best.     

FGF19 as a postprandial, insulin-independent activator of hepatic protein and glycogen synthesis

Fibroblast growth factor (FGF) 19 is an enterokine synthesized and released when bile acids are taken up into the ileum. We show that FGF19 stimulates hepatic protein and glycogen synthesis but does not induce lipogenesis. The effects of FGF19 are independent of the activity of either insulin or the protein kinase Akt and, instead, are mediated through a mitogen-activated protein kinase signaling pathway that activates components of the protein translation machinery and stimulates glycogen synthase activity. Mice lacking FGF15 (the mouse FGF19 ortholog) fail to properly maintain blood concentrations of glucose and normal postprandial amounts of liver glycogen. FGF19 treatment restored the loss of glycogen in diabetic animals lacking insulin. Thus, FGF19 activates a physiologically important, insulin-independent endocrine pathway that regulates hepatic protein and glycogen metabolism.     

The product of the mos proto-oncogene as a candidate "initiator" for oocyte maturation

The endogenous c-mos product, pp39mos, is required for progesterone-induced meiotic maturation in Xenopus oocytes. Treatment of oocytes with progesterone induced a rapid increase in pp39mos that preceded both the activation of maturation promoting factor (MPF) and germinal vesicle breakdown (GVBD). Microinjection of synthetic mos RNA into oocytes activated MPF and induced GVBD in the absence of progesterone. Thus, the mos proto-oncogene product may qualify as a candidate "initiator" protein of MPF and is at least one of the "triggers" for G2 to M transition.     

circ-13267通过let-7-19/ERBB4通路调控蛋鸭卵泡颗粒细胞凋亡

[背景]蛋鸭卵泡发育是决定其产蛋性能的关键因素.已有研究表明,禽类卵泡发育是极为复杂的生物学过程,目前人们已对家禽的卵泡发育模式有了一定的了解,但作为决定产蛋量的重要因素,卵泡发育的具体调控机理仍需进一步深入研究.颗粒细胞是卵泡中主要的功能细胞,可调控卵泡膜细胞和卵母细胞的生长、分化和成熟,同时也精确的调控卵泡的生长发...