Acrylonitrile inhalation in rats: II. Excretion of thioethers and thiocyanate in urine

In male Wistar rats, the inhalation exposure to acrylonitrile (AN), 271 mg X m-3, 8 hours a day, 5 days a week, did not affect protein sulfhydryl concentration in liver and blood and decreased glutathione concentration in the liver, but not in the brain at the end of the fifth exposure. The urinary excretion of the main AN metabolites, thioethers (AN-mercapturic acids) and thiocyanate was proportional to the inhaled AN concentration (57, 125, 271 mg X m-3, respectively) in a single exposure for 12 hours, and their mutual ratio was greatly different from that after injection of AN. The results revealed that the urinary excretion of thioethers is a very sensitive and dose-related indicator of exposure to AN and extrapolation of the results indicates that the exposure to AN concentration below 10 mg X m-3 could thus be demonstrated.     

Thermal melting and circular dichroism of DNA complexes with (Lys-Ala-Ala)10 and (Lys-Ala-Ala)n: effect of polypeptide chain length

DNA complexes with polypeptides (Lys-Ala-Ala)₁)] and (Lys-Ala-Ala)₃₄ have been studied using the methods of thermal melting and circular dichroism. Derivative melting curves of (Lys-Ala-Ala)₁₀ DNA differed substantially from those of (Lys-Ala-Ala)₃₄ prepared either by salt gradient dialysis or by direct mixing. Melting curves of the former complex were unimodal or bimodal with T_m increasing continuously withn input lysin-to-DNA phosphate ratio (r); those of the latter complex consisted of three separate transitions with T_m values almost independent of r. Complete reversibility of binding in the (Lys-Ala-Ala)₁₀-DNA system but a slow redistribution of (Lys-Ala-Ala)₃₄ on DNA at low temperature were found in the redistribution experiments Much faster redistribution from denatured to native DNA occurs at the temperature of melting, contributing to the unusual trimodal melting pattern. Circular dichroism curves are very similar for both complexes and indicate little change of DNA conformation upon polypeptide binding.     

人体单臂间歇运动对发汗调定点的影响

本工作系在微小气候相对恒定条件下,对10名健康男青年每人进行四项实验。实验 Ⅰ 为测定双侧腿足浸入43℃水中,诱发左前臂屈侧显现定量汗点时的口腔温度(舌下)阈值,作为发汗调定点参考值(ToSSP);实验 Ⅱ 为 Ⅰ 附加右臂间歇轻负荷运动(77W)时测定 ToSSP,部分对象还记录了皮肤电反应;实验 Ⅲ、Ⅳ 为 Ⅰ、Ⅱ 均附加4.5m/s 气流(22—25℃)直吹头面部,再分别测定 ToSSP。实验 Ⅰ 与 Ⅱ 同体对照22人次,Ⅲ 与 Ⅳ 同体对照24人次。结果表明,实验 Ⅱ、Ⅳ 的 ToSSP 均值及其潜伏期均值分别较 Ⅰ、Ⅲ 者降低(P<0.01)或缩短(P<0.001);Ⅰ、Ⅱ间的 ToSSP 均值差、潜伏期均值差,分别与 Ⅲ、Ⅳ 之间者无显著差异(P>0.2);Ⅱ、Ⅳ 的ToSSP 均值各与其实验开始前的口温均值亦无明显差异(P>0.5)。此结果支持运动时体温调定点下降的论点,并提示在研究体温调定点活动时,以 ToSSP 为指标较用发汗速率为优越,因 ToSSP 不为许多干扰因素所影响。     

Amplification of a Cryptosporidium parvum gene fragment encoding thymidylate synthase.

Currently, there is no effective therapy for cryptosporidiosis and it is unclear why antifolate drugs which are effective treatments for infections caused by closely related parasites are not also effective against Cryptosporidium parvum. In protozoa, the target of these drugs, dihydrofolate reductase (DHFR), exists as a bifunctional enzyme also manifesting thymidylate synthase (TS) activity and is encoded by a fused DHFR-TS gene. In order to prepare a probe to isolate the C. parvum DHFR-TS gene we have used degenerate oligonucleotides whose sequences are based on strongly conserved regions of TS protein sequence to prime the polymerase chain reaction (PCR) with C. parvum DNA. The PCR amplified a 375-bp DNA fragment which was cloned and sequenced; the deduced amino acid sequence had significant identity with known TS sequences, including strict conservation of all phylogenetically invariant TS amino acid residues. The cloned PCR fragment was used as a probe to isolate a number of overlapping clones from a C. parvum genomic library which were definitively shown to be of cryptosporidial origin by genomic Southern and molecular karyotype analyses. The deduced protein sequence of C. parvum TS was most similar to the bifunctional TS enzymes of Plasmodium chabaudi and Plasmodium falciparum.     

我国恙虫蚴的三个新种(蜱螨目, 恙虫科)

近几年来,我国科学家们在恙虫方面的研究工作巳经取得了显著的成就。然而,这对于拥有辽阔疆土的我国来说,实在只不过是一个开始。我们在这方面的工作也做得很少,虽然从1953年开始收集标本,由于各种条件所限制,未能及时整理,以致大量标本散失或霉烂,十分可惜。本文内容,仅仅是将我站恙虫病调研工作组1957年在本省各地所采集的材料中的三种恙虫蚴加以描述,该三种恙虫蚴均系文献上未曾记载过的种类。     

假菠萝麻蛋白酶分离纯化及特性研究

从假菠萝麻叶汁中用乙醇分部沉淀法得到一种蛋白酶,对酪蛋白有强烈的水解活性,经Ｓｅｐｈａｄｅｘ Ｇ－１００柱层析和ＳＰ－Ｓｅｐｈａｄｅｘ Ｃ－５０离子交换柱层析等步骤纯化,可得到六角形结晶。结晶酶液经ＰＡＧＥ圆盘电泳,每条胶柱上只显示一条蛋白带,其活性在ｐＨ４。５－１０、５５℃范围内较稳定,最适ｐＨ８．５最适温度５０℃,Ｋｍ（酪蛋白）值为０．１８５％（Ｗ／Ｖ）。用ＳＤＳ－ＰＡＧＥ和Ｓｅｐｈａｄｅｘ     

一种新发现的镉超积累植物--钻叶紫菀(Aster subulatus Michx.)

通过野外调查和温室营养液砂培试验,发现并鉴定出钻叶紫菀（Aster subulatus Michx.）是一种新的镉（Cd）超积累植物。调查结果发现,钻叶紫菀对土壤中高含量的Cd有很强的忍耐、吸收和积累能力,其地上部茎、叶Cd含量分别为90.0-150.7mg/kg和119.8-172.6mg/kg,平均值分别为132.8mg/kg和139.2mg/kg。砂基营养液培养试验证明,钻叶紫菀对生长介质中的Cd有很强的忍耐能力,当生长介质中Cd浓度高达150mg/L时,植株仍生长正常,其株高与对照相比无显著差异;地上部Cd含量及其积累量均随生长介质中Cd浓度的增加而增加,当生长介质中Cd浓度为120mg/L时,地上部茎Cd含量和积累量达到最高值,分别为5672.50mg/kg、4.93mg/株。结果表明,钻叶紫菀是一种新的Cd超积累植物,为今后探明植物超积累Cd的机理和Cd污染土壤的植物修复提供一种新的种质资源。     

基于N蛋白单克隆抗体的小反刍兽疫病毒抗体检测胶体金试纸条的研制

本研究旨在建立一种简便、快捷、可直观检测小反刍兽疫病毒(peste des petits ruminants virus,PPRV)抗体的检测方法。将pET-32a-N重组质粒转化至大肠杆菌(Escherichia coli) Rosetta(DE3)感受态细胞中进行诱导表达,以纯化的PPRVN蛋白免疫8周龄BALB/c小鼠,取其脾细胞与SP2/0骨髓瘤细胞进行融合,间接酶联免疫吸附试验(enzyme-linked immunosorbent assays, ELISA)筛选及亚克隆,获得了抗PPRV N蛋白的单克隆抗体。将PPRV N蛋白分别作为金标抗原及检测线(T线)包被抗原、单克隆抗体作为质控线(C线)包被抗体,组装成检测PPRVN蛋白抗体的胶体金免疫层析试纸条。结果显示：成功获得1株能稳定分泌抗N蛋白抗体的杂交瘤细胞株,命名为1F1;间接ELISA检测1F1腹水效价为1:128000;亚类鉴定结果为IgG1,轻链为kappa链。Westernblotting结果显示,1F1能与PPRV N蛋白特异性结合;间接免疫荧光(indirect immunofluorescent ass...     

circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移

目的 鼻咽癌是一种来源于鼻咽上皮的恶性肿瘤,其临床特征之一是易发生淋巴转移,但是目前鼻咽癌转移的分子机制尚未阐明。circPVT1是由PVT1基因2号外显子反向拼接形成的环状RNA (circRNA),在多种肿瘤中表达上调,本文探讨了circPVT1在鼻咽癌侵袭迁移中的作用和分子机制。方法 通过RT-qPCR检测circPVT1及其下游miRNA和FSCN1在鼻咽癌细胞的表达情况,Transwell和划痕愈合实验检测circPVT1对鼻咽癌细胞侵袭迁移的影响,RNA pull-down实验检测circPVT1结合的miRNA,双荧光素酶报告实验检测miR-24-3p和let-7a-5p靶向抑制FSCN1 mRNA表达。结果 在鼻咽癌细胞中过表达circPVT1可以促进鼻咽癌细胞侵袭迁移,而敲低circPVT1则可以抑制鼻咽癌细胞的侵袭迁移。进一步研究发现,circPVT1可以通过竞争性吸附miR-24-3p和let-7a-5p,上调FSCN1的表达,从而促进鼻咽癌细胞的侵袭迁移。结论 circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移,证实c...