The dynamics of in vitro 17 β-estradiol secretion by isolated ovarian follicles of the rainbow trout (Oncorhynchus mykiss)

This study investigated the effects of human chorionic gonadotropin (hCG), 17-hydroxyprogesterone (17P) and testosterone (T) on the in vitro production of 17-estradiol (E₂) by isolated ovarian follicles of the rainbow trout (Oncorhynchus mykiss). 17P at 100 ng ml^-1, and hCG at 100 IU ml^-1 stimulated E₂ production relative to controls, whereas lower doses were ineffective. T was the most effective in stimulating E₂ production, followed by 17P and hCG respectively. The timecourse of E₂ production was investigated for both static culture, and incubations with media replacement, with follicles being exposed to hormone treatment for 30 min, 1 or 3 h, or constantly. E₂ production was observed after 30 min, 3 and 3-6 h in response to T, 17P and hCG respectively. Under static culture, E₂ levels reached maximal levels in 6 h. Longer incubations resulted in further metabolism of E₂ to E₂-glucuronide, which resulted in the blurring of treatment effects after 18 h. Incubations with media replacement resulted in higher E₂ production than in static culture. The results indicate that a 6 h incubation period is sufficient to produce significant increases in E₂ production in response to hCG, 17P and T, and that incubations longer than 12 h result in losses E₂ from the incubation media. These findings have implications for the validity of using static cultures to examine the effects of hormone treatment on the activity of steroid converting enzymes in vitro.     

Nitrate uptake by Eriophorum vaginatum controls N2O production in a restored peatland

The clear dependence of N₂O production through denitrification on available nitrate in soil has been shown in many studies. Since N availability similarly limits the growth of plants, the resource competition with vegetation limits the activity of denitrifying microbes and may consequently moderate the N₂O emissions from peatlands. We used uptake by Eriophorum vaginatum L. as a vegetation competition factor for microbes. The species was selected for the experiment because it has high nutrient use efficiency in low-nutrient conditions and high nutrient uptake efficiency in luxuriant nutrient conditions. We measured gaseous N flux as N₂O (end product of denitrifier activity) in a restored peatland in central Finland with acetylene inhibition technique over a growing season from sample plots with varying addition levels and E. vaginatum cover. The resource competition effects were analysed with a model that used exponential decay dependence of N₂O flux on the leaf area of E. vaginatum, and saturating response of N₂O flux to addition level. The model explained the variation in N₂O fluxes well (R²=0.86). The model simulation showed that the increasing nutrient uptake of E. vaginatum decreased the N₂O fluxes exponentially. Simultaneously, denitrification appeared to saturate even in conditions with high availability of and low level of competition by vegetation. Thus, E. vaginatum is an effective competitor for in sedge-dominated peatlands that controls the availability of for denitrification, and consequently moderates the N₂O emissions from peatlands.     

马传染性贫血弱毒疫苗株致弱过程中表面蛋白gp90的进化分析

为进一步研究马传染性贫血病毒(EIAV)弱毒疫苗的减毒机制,本实验对EIAV弱毒疫苗的原始种毒EIAVLN40、亲本病毒株EIAVDV、驴白细胞弱毒疫苗EIAVDLV121和EIAVDV减毒过程中的3个中间代次病毒(EIAVDLV32、EIAVDLV62和EIAVDLV92)的gp90基因进行测序分析。结果显示,适应白细胞培养的病毒株的进化距离更接近,与亲本病毒株处于进化树的不同分支。与强毒株相比,适应白细胞培养的病毒株在9个位点发生优势氨基酸的转换和V3区糖基化位点191NSSN194的缺失。此外,伴随EIAV毒力减弱的过程,有8个位点出现优势氨基酸残基的转换,在各代次病毒株中V4区具有糖基化位点237NNTW240和246NETW249的克隆所占的比例逐渐降低,其中EIAVDLV121的糖基化位点237NNTW240完全缺失。     

应用聚合酶链反应检测伪狂犬病病毒DNA

选用标准的伪狂犬病病毒（ＰＲＶ）闽Ａ株，经ＢＨＫ２１细胞培养，提取ＰＲＶＤＮＡ作为摸板；合成１对２０－ｍｅｒ寡核苷酸作为引物；选择扩增序列由２６２个碱基对组成的位于编码多糖蛋白ｇｐ５０基因，用耐热的Ｔａｑ－ＤＮＡ聚合酶经３０个循环以后，扩增的产物直接用凝胶电泳检测，并用标准分子量确定。结果表明：以ＰＲＶＤＮＡ作为模板进行扩增，有扩增产物生成，以同科的疱疹病毒ＤＮＡ作为模板在相同的条件下进行ＰＣＲ扩增，无扩增产物生成，说明ＰＲＶＰＣＲ扩增是特异的。ＰＣＲ技术检测ＰＲＶＤＮＡ敏感度为２８．５ｐｇ．ＰＲＶＰＣＲ技术的建立，为伪狂犬病诊断和流行病学研究提供了更敏感、可靠的手段。     

Cryopreservation of sheep red blood cells. 3. Complement titrations with frozen sensitized cells

The effect of different suspending and washing procedures for recovery of sensitized sheep erythrocytes (EA) after freezing at −196°C was investigated. Best results were obtained using gelatin-veronal-buffered saline-sucrose containing 0.15 mM-Ca and 1 mM-Mg (GVBSM⁺⁺-sucrose) as the suspending and first washing buffer. The cryoprotective agents tested were polyvinylpyrrolidone (PVP), neutralized PVP, purified PVP and a gum product, Avelex 1030. All PVP preparations tested gave good results as cryoprotectants in terms of cell recovery after thawing whereas Avelex 1030 was less satisfactory. The EA cells frozen in the presence of untreated PVP showed, however, increased susceptibility to the hemolytic action of complement, whereas cells frozen with purified or neutralized PVP gave titers similar to that obtained with fresh cells. Good results were also obtained with Avelex 1030. Complement titrations with frozen EA cells were more reproducible than titrations with fresh cells.     

Cryopreservation of Sheep Red Blood Cells: 4. Titrations of The First Complement Component with Frozen Eac4 Cells

The cryoprotection of the sheep erythrocyte intermediate EAC4 cells, used as reagent in titration of the first complement component, Gl, was investigated. The cryoprotective agents tested were untreated polyvinylpyrrolidone (PVP), purified PVP, neutralized PVP and a hydroxyethylated potato starch of high viscosity, Avelex 1030, hydrolyzed for 40 min. Recovery of EAG4 cells after thawing was 80–90 %, with best results using untreated, purified or neutralized PVP. The EAG4 cells frozen in the presence of untreated PVP showed, however, increased susceptibility to the hemolytic action of Gl, whereas cells frozen with purified or neutralized PVP or with Avelex 1030 gave titers similar to that obtained with fresh cells. Gl titrations with frozen and thawed EAG4 cells gave more reproducible results than those obtained when titrations were performed with fresh separately prepared cells.     

应用PCR/RFLP技术对广西禽白血病病毒的检测与分型研究

对2000～2003年间从广西的南宁、玉林、桂林、钦州、柳州、梧州等地采集的有肿瘤/可疑肿瘤的250份鸡病例进行肿瘤病的检测.结果发现,外源性禽白血病阳性的有32份,阳性率为12.8%.其中,同时为马立克氏病阳性的有30份,两者共感染率高达93.75%(30/32);根据禽白血病病毒囊膜糖蛋白gp85基因的限制性片段长度多态性分析,对其中20份外源性禽白血病病毒进行分型鉴定,结果证实全部属于A亚群.     

三黄鸡临床血管瘤病例中分离出A亚群与J亚群禽白血病病毒

为了解禽白血病病毒在广西鸡群中流行情况,采用DF-1细胞接种、细胞培养上清p27抗原检测、PCR扩增,对临床血管瘤型禽白血病的三黄鸡病料进行了病毒分离,并对分离病毒gp85基因进行测序和序列比较。结果表明,从1只病鸡同时分离到了一株A亚群禽白血病病毒(ALV-A)与一株J亚群禽白血病病毒(ALV-J),分别命名为HG01-A株和HG01-J株。ALV-A gp85与7株A亚群氨基酸同源性为85.8%~87.5%,与A亚群美国株MQNCSU同源性最高为87.5%,与A亚群原型株RSA同源性为86.9%。而ALV-J gp85与7株毒株核酸序列同源性为84.0%~93.8%,与广东株XX2-08以及四川株SCSM01同源性最高为93.8%,与英国原型株HPRS103同源性为90.2%。进化分析进一步表明,HG01-A与各参考株亲缘关系较远,HG01-J与SCSM01亲缘关系最近。本研究首次从同一只广西三黄鸡中同时分离到ALV-A及ALV-J,进一步完善了我国地方品种鸡群中禽白血病的流行病学信息。     

油菜生态型雄性不育材料H90S温光特性研究

1995～1999年。对H90S进行了分期播种和光照试验．结果表明：生态型核不育系H90S在开花进程中．不育度随开花进程的延伸而逐渐下降．随着分支所在位置的增加而降低。H90S在经过16及24h光照处理后．株高增加．出苗至初花日效减少．出苗至成熟日效缩短．不育度明显降低。不育栋串与花芽分化始期气温、花芽分化期光照长度呈极显著负相关；不育度与初花期气温、花芽分化期至初花期活动积温之间呈显著负相关．与花芽分化期光照时效及初花前光照时效之间相关达极显著水平。     

农林类高职大学生心理健康水平现状与对策

用症状自评量表(SCL-90)对杨陵职业技术学院307名高职生的心理健康状况进行测查。结果表明,农林类高职生这一群体中有明显心理问题的占12.05%;SCL-90各因子分值均高于全国正常成人常模而低于全国大学生常模;男女生样本Z检验的结果差异并不显著;独生子女心理健康状况不如非独生子女的心理健康状况。