东北白眉蝮蛇毒细胞毒组分的分离制备及活性鉴定

用离子交换层析和凝胶过滤法从东北白眉蝮蛇毒中分离出一种具有较强的细胞毒活性的蛋白质。这种蛋白质对肿瘤细胞的细胞毒作用元选择性,但各种肿瘤细胞的敏感性有一定差别。对正常人体细胞也有一定的细胞毒性作用,与肿瘤细胞相比,敏感性较低。这种蛋白质加热到56℃,30分钟,细胞毒活性稳定。4℃及-20℃保存4个月,细胞毒活性稳定。PH值低于4及高于9时,可使其完全失活。     

天祝高寒珠芽蓼草甸群落的热值和营养成分的初步研究

 本文报告了甘肃天祝高寒珠芽蓼(Polygonum viviparum)草甸群落地上及地下四部分生物量的热值和营养成分动态,并对其放牧利用的价值进行了总的评价。 6—9月现存量的热值平均为18330焦／克干物质,或20279焦／克去灰分物质,较立枯物+凋落物、活根、死根的平均值为大;死根略大于活根。在珠芽蓼及其他大多数植物种子成熟期的8月下旬,现存量的热值最大,其他三部分的热值变化也有其各自的特点。现存量6—9月的平均营养成分以绝对干重计为：粗蛋白13.52%,粗脂肪2.25,粗纤维22.99,无氮浸出物51.88,粗灰分9.61(其中钙1.627,磷0.164);在时间变化上四部分各有其特点。根据地形、植物组成、产量、易食性、适口性、热值和营养成分等综合条件,认为珠芽蓼草甸是良好的放牧地。     

内蒙古锡林郭勒草原植被结构的遥感图象分析

 本文利用遥感图象分析技术对内蒙古锡林郭勒草原植被各层次空间结构(大、中、小、微)及其与相应环境因素之间的关系进行了分析,并对各类草原的地上生物量及理论载畜量给予估算。分析结果表明：锡林郭勒草原植被的地域分异规律明显;植被的大结构主要受大气候因素及大的地貌单元控制：地形、水文网络是影响植被中结构的主要因素;而植被微、小结构的形成主要受局部地形、地表水、基质及人为干扰因素的制约。     

猪肠毒素源性大肠杆菌K88ac粘附抗原的核苷酸序列分析

 本文对国内流行的猪肠毒素源性大肠杆菌K88ac抗原的结构基因的核苷酸序列进行了测定。该基因由849对核苷酸组成,编码了283个氨基酸的蛋白亚单位及21个氨基酸的信号肽。与国外报道的K88ac序列的不同是我们发现一个碱基的点突变,导致在抗原决定簇内一个氨基酸的改变。从核苷酸序列推导出的氨基酸序列与另两种亚型进行了比较。     

化学法合成生物素标记寡核苷酸探针

 生物素可通过氨烷基磷酰胺基团连接到寡核苷酸5'末端,反应在水溶液中进行,核苷酸的侧链基团不用保护。我们以这种化学法合成了生物素标记的寡核苷酸探针,其显色灵敏度达50pg,杂交灵敏度达0.4fmol,并与酶标生物素寡核苷酸探针进行了比较,也对两种不同显色体系作了比较。     

Initiation of minus-strand RNA synthesis by the brome mosaicvirus RNA-dependent RNA polymerase: use of oligoribonucleotide primers.

Various DNA- and RNA-dependent RNA polymerases have been reported to use oligoribonucleotide primers to initiate nucleic acid synthesis. For the brome mosaic virus RNA-dependent RNA polymerase (RdRp), we determined that in reactions performed with limited GTP concentrations, minus-strand RNA synthesis can be stimulated by the inclusion of guanosine monophosphate or specific oligoribonucleotides. Furthermore, guanylyl-3',5'-guanosine (GpG) was incorporated into minus-strand RNA and increased the rate of minus-strand RNA synthesis. In the presence of GpG, RdRp's Km for GTP decreased from 50 microM to approximately 3 microM while the Kms for other nucleotides were unaffected. These results have implications for the mechanism of initiation by RdRp.     

Chromosome aberrations in workers of nuclear-power plants

The frequencies of chromosome aberrations in 135 workers from nuclear-power plants were compared with those in 135 age-matched controls. A total of 135,000 cells was scored. The frequencies of dicentric chromosome were 1.67 × 10⁻³ in the exposed group and 0.49 × 10⁻³ in the control group and those of chromosome-type deletion were 3.33 × 10⁻³ and 1.10 × 10⁻³, respectively. The frequencies of all types of chromosome aberrations in the exposed subjects were higher than those in the control group, but no significant trend of dose-dependent increase was observed when only the exposed group were considered. Poisson regression analysis, with both exposed and control included, showed that there was a significant association of chromosome aberration with radiation dose and the duration of work, but not with age, smoking habit and alcohol intake. It was also found that recent exposure to radiation, within the last 5 years, had contributed more to the observed chromosome aberration than earlier exposure.     

Resuscitation of Vibrio cholerae O1 strain TSI-4 from a viable but nonculturable state by heat shock

Abstract Vibrio cholerae strain TSI-4 was incubated in an M9 salt solution at 15 °C for more than 100 days. The plate counts showed no viable cells on day 30, but a broth culture from that day showed the growth of bacteria. However, after 35 days the bacteria entered the nonculturable state, based on the assessment of both the plate counts and broth culture. A portion of the culture was heated at 45 °C for 1 min in a water bath and subsequently plated onto a nutrient agar plate. More than 1000 colonies were recovered after this heat-shock treatment. The recovered cells showed the same chromosomal DNA pattern in the restriction map and the same outer membrane protein pattern in SDS-PAGE. Recovery of viable cells by heat-shock was achieved in cultures grown on M9 salt but not from cultures grown in phosphate-buffered saline. This suggests that the presence of NH₄Cl in the M9 salt solution may support the growth of the bacteria in a low nutrient medium, while also playing an important role in resuscitation.     

从水稻同源三倍体中鉴定出无融合生殖种质TAR

水稻杂种优势的成功应用使水稻单产提高了20%,这主要得益于70年代初细胞质雄性不育系的发现和利用。但传统的三系法杂交水稻必须做到不育系、保持系、恢复系“三系”配套,选育程序和杂交种子生产环节较复杂,以致培育目标组合的周期长、效率低、推广环节多,同时种子成本高、价格贵[1]。80年代光敏核不育水稻以其“一系两用、配组自由”等优越性大有取代三系杂交水稻的趋势。但是,光敏核不育特性同时又受温度的调控,加之育性波动等缺陷使两系杂交水稻的研究和利用受到严重制约[2]。80年代后期,科技工作者开始探索利用无融合生殖固定水稻杂种优…