5'ETS rRNA processing facilitated by four small RNAs: U14, E3, U17, and U3.

The nucleolus, the compartment in which the large ribosomal RNA precursor (pre-rRNA) is synthesized, processed through a series of nucleolytic cleavages and modifications into the mature 18S, 5.8S, and 28S rRNAs, and assembled with proteins to form ribosomal subunits, also contains many small nucleolar RNAs (snoRNAs). We present evidence that the first processing event in mouse rRNA maturation, cleavage within the 5' external transcribed spacer, is facilitated by at least four snoRNAs: U14, U17(E1), and E3, as well as U3. These snoRNAs do not augment this processing by directing 2'-O-methylation of the pre-rRNA. A macromolecular complex in which this 5'ETS processing occurs may then function in the processing of 18S rRNA.     

大肠杆菌rpoH基因的克隆,表达及其产物的纯化

本文用ＰＣＲ方法获得大肠杆菌热休克蛋白转录因子σ３２的编码基因ｒｐｏＨ,并克隆在含有ｔａｃ启动子的表达载体ｐＵＨＥ中,经ＩＰＴＧ诱导,在大肠杆菌中表达了Ｃ端融合有６个寡聚组氨酸的σ３２。表达产物经金属螯合层析一步纯化,达到ＳＤＳ－ＰＡＧＥ银染一条带纯度,氨基酸组成分析及Ｎ端序列分析结果与文献报道一致。３５Ｓ细胞内参入实验表明：即使在较低的温度下,表达产物σ３２（Ｈｉｓ）６也能导致热休克蛋白如ＧｒｏＥｌ、ＤｎａＫ、Ｈｔｐ的大量合成．     

新疆血革螨属一新种（蜱螨亚纲：血革螨科）

本文报道血革螨属一新种,命名为狭背血革螨,新种Ｈａｅｍｏｇａｍａｓｕｓａｎｇｕｓｔｕｓｓｐ．ｎｏｖ．采自新疆乌苏,寄主为野兔。     

Sources of variation in the reproductive performance of ewes inseminated with frozen-thawed ram semen by laparoscopy

Fertility data from 8 artificial insemination programs, involving more than 5000 ewes and 110 rams in 3 flocks, were analyzed to determine variation due to individual AI program and ram in the reproductive performance of ewes inseminated with frozen-thawed semen by laparoscopy. The semen had been previously frozen by commercial AI centers in either pellets or straws. Both AI program and individual ram affected the proportion of ewes pregnant and the number of fetuses per ewe inseminated, but not the number of fetuses per pregnant ewe. Semen samples from 97 of the rams used were analyzed on a Hamilton Thorn HTM 2000 image analyzer for sperm concentration, percentage of motile and progressively motile spermatozoa, mean progressive velocity, and mean linear index. The correlations between these traits and reproductive performance obtained after insemination were calculated. There was large variation in the quantity and quality of the frozen semen, but only the number of total and motile spermatozoa inseminated per ewe was correlated with fertility (0.25 and 0.26, respectively). Regression analysis showed that none of the traits measured were useful for predicting fertility.     

龙血树真菌群及其对血竭形成的影响

从柬埔寨龙血树（Ｄｒａｃａｅｎａｃｏｃｈｉｎｃｈｉｎｅｎｓｉｓ）茎杆中分离到３０３株真菌,其中镰刀菌属（Ｆｕｓａｒｉｕｍ）菌株占总分离频率的５２％,其次是短梗霉（Ａｕｒｅｏｂａｓｉｄｉｕｍ）和枝孢霉（Ｃｌａｄｏｓｐｏｒｉｕｍ）。通过活体接种对血竭产生的影响试验表明,对血竭形成起重要作用的真菌主要是禾谷镰刀菌龙血树变种（Ｆ．ｇｒａｍｉｎｕｍｖａｒ．ｄｒａｃａｅｎａ）等４株红色镰刀菌,可使血竭形成量提高６６％－１２０％。     

甜玉米籽实含糖量的配合力分析

采用不完全双列杂交设计研究了 6个母本3个父本甜玉米自交系籽实含糖量的配合力效应。结果表明,父母本一般配合力和特殊配合力效应均方都显著。根据各亲本的表现把亲本5033归为一般配合力高而特殊配合力方差大的最理想类型;亲本5012和5011属一般配合力高而特殊配合力方差小的类型;亲本5018、5034、5028和5024为一般配合力低,但特殊配合力方差高的类型; 亲本5023和5009属一般配合力效应和特殊配合力方差都低的类型,最缺少实用价值。     

DNA topology: Topoisomerases keep it simple

The ability of type II DNA topoisomerases to perturb the equilibrium distributions of DNA topoisomers is a consequence of their ability to hydrolyse ATP. A sliding mechanism of topoisomerase action has been proposed to account for this phenomenon.     

西藏厚厉螨属一新种和毛绥螨属一新种(蜱螨亚纲:厚厉螨科,裂胸螨科)

本文报道革螨二新种,西藏厚厉螨Pachylaelapsxizangensissp．nov．和亚东毛绥螨Lasioseiusyadongensissp．nov,1985年采自西藏亚东。     

雕盾螨属一新种记述（蜱螨亚纲：巨螯螨科）

本文记述雕盾螨属一新种;吴氏雕盾螨采自吉林省白城的土壤和马粪中。模式标本保存于全国鼠疫布氏菌病防治基地。     

氯喹导致大鼠肌组织载脂蛋白E大量表达

载脂蛋白E(ApoE)与迟发的家族性及孤发性阿尔茨海默(Alzheimer)病密切相关. 氯喹慢性中毒可诱发某些肌病理改变, 出现β淀粉样蛋白(βAP)与tau蛋白等的沉积, 与Alzheimer脑中见到的病理改变类似. 为分析这一改变的机制, 用逆转录结合多聚酶链反应技术(RT-PCR)对氯喹处理的大鼠肌肉中ApoE表达的改变进行了研究. 在PCR定量中采用了一种稳定表达的内源性甘油醛-3-磷酸脱氢酶mRNA作为内部参照. PCR扩增在很宽的循环数范围内成线性, 且靶mRNA与参照mRNA的扩增效率相当. 氯喹处理后大鼠肌肉中ApoE mRNA的表达从第6周开始增加, 第8周后超过对照组的20多倍. 结果提示, ApoE在氯喹慢性中毒所致的大鼠肌病理改变中发挥某些作用.