黑河上游灌丛建群种中国沙棘自由授粉子代父本分析和花粉流

利用SSR分子标记对中国沙棘（Hippophae rhamnoides ssp. sinensis Rousi）自由授粉的种子进行父本分析,研究其子代的父本来源和花粉散布模式。结果显示：在80%的置信水平上,193个子代中有104个个体可以确定花粉来源;在20个确定的父本中,16个为中国沙棘,4个为肋果沙棘（H.neurocarpa S.W.Liu et T.N.He）。传粉格局分析结果显示,中国沙棘有效花粉散布范围为3~71 m,平均距离为20.4 m,2株母本分别有87.23%和78.95%的有效花粉来自距其30 m的范围之内,研究结果表明中国沙棘自然种群以近距离传粉为主。此外,在黑河上游沙棘杂交带中,中国沙棘子代中的肋果沙棘花粉平均贡献率达到14.84%,表明中国沙棘与肋果沙棘存在较高的种间当代花粉流。     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

固定化葡萄糖异构酶最适pH值的调节

用多孔强碱性三乙醇胺基聚苯乙烯树脂作为载体,用CNBr与载体上多羟基作用共价偶联葡萄糖异构酶(GI)。最适偶联条件表明:CNBr量增多,蛋白载量增加,但比活下降。固定化葡萄糖异构酶(IGI)最适反应温度比天然酶提高15℃。并系统地研究了影响IGI活力-pH的曲线的各种因素:用具有不同平均孔径的载体(R=137A,185A,230A,365A)固定化GI,在低离子强度条件下(0.0064mol/L),测定其最适pH值分别7.76,7.56,7.50,8.20。选择平均孔径为230A且具有不同数量三乙醇胺基的载体(0.94,1.05,1.13,1.37mmol/g干胶)分别固定化GI,其最适pH值分别为7.70,7.50,7.46,7.36。     

Expression of a gene encoding a rabbit sperm membrane protein in mammalian cells.

A general mammalian expression vector designated pSV2-EP was reconstructed by inserting an oligonucleotide fragment into pSV2-dhfr. This vector allowed insertion of cDNAs with EcoRI cohesive ends. The pSV2-EP contains a simian virus 40 (SV40) early promoter, origin for DNA replication, SV40 poly-A site, splicing site, an initiator ATG downstream from the promoter and an EcoRI site for the insertion of cDNA fragment screened from lambda gt11 expression libraries. A recombinant plasmid (pS-VRS-1) was constructed by inserting RSD-1, a cDNA encoding a rabbit sperm tail protein, into the EcoRI site of the pSV2-EP vector. Chinese hamster ovarian (CHO) dhfr-negative cells were cotransformed with pSV2-dhfr and pSVRS-1 by the calcium phosphate method. In selective culture medium without thymidine and hypoxanthine, several cell lines were obtained containing mRNA and DNA that hybridized with RSD-1. One of these transformed cell lines stained intensely with anti-rSMP-B antibodies, demonstrating that the RSD-1 was expressed in the transformed CHO cells.     

Site-specific mutagenesis of an essential histidine residue in pancreatic cholesterol esterase

The histidine residue essential for the catalytic activity of pancreatic cholesterol esterase (carboxylester lipase) has been identified in this study using sequence comparison and site-specific mutagenesis techniques. In the first approach, comparison of the primary structure of rat pancreatic cholesterol esterase with that of acetylcholinesterase and cholinesterase revealed two conserved histidine residues located at positions 420 and 435. The sequence in the region around histidine 420 is quite different between the three enzymes. However, histidine 435 is located in a 22-amino acid domain that is 47% homologous with other serine esterases. Based on this sequence homology, it was hypothesized that histidine 435 is the histidine residue essential for catalytic activity of cholesterol esterase. The role of His435 in the catalytic activity of pancreatic cholesterol esterase was then studied by the site-specific mutagenesis technique. Substitution of the histidine in position 435 with glutamine, arginine, alanine, serine, or aspartic acid abolished the ability of cholesterol esterase to hydrolyze p-nitrophenyl butyrate and cholesterol [14C]oleate. In contrast, mutagenesis of the histidine residue at position 420 to glutamine had no effect on cholesterol esterase enzyme activity. The results of this study strongly suggested that histidine 435 may be a component of the catalytic triad of pancreatic cholesterol esterase.     

Comparison of charge movement components in intact and cut twitch fibers of the frog. Effects of stretch and temperature

Charge movements were measured in frog intact fibers with the three-microelectrode technique and in cut fibers with the double Vaseline gap technique. At 13-14 degrees C, the ON segments of charge movement records from both preparations showed an early I beta component and a late I gamma hump component. When an intact fiber was cooled to 4-7 degrees C, the time-to-peak of I gamma (tp,gamma) was prolonged, but I gamma still appeared as a hump. Q-V plots from intact fibers at 4-7 degrees C were fitted with a sum of two Boltzmann distribution functions (method 1). The more steeply voltage-dependent component, identified with Q gamma, accounted for 32.1% (SEM 2.2%) of the total charge. This fraction was larger than the 22.6% (SEM 1.5%) obtained by separating the ON currents with a sum of two kinetic functions (method 2). The total charge in cut fibers stretched to a sarcomere length of 3.5 microns at 13-14 degrees C was separated into Q beta and Q gamma by methods 1 and 2. The fraction of Q gamma in the total charge was 51.3% (SEM 1.7%) and 53.7% (SEM 1.8%), respectively, suggesting that cut fibers have a larger proportion of Q gamma:Q beta than intact fibers. When cut fibers were stretched to a sarcomere length of 4 microns, the proportion of Q gamma:Q beta was unchanged. Between 4 and 13 degrees C, the Q10 of l/tp,gamma in intact fibers was 2.33 (SEM 0.33) and that of 1/tau beta was less than 1.44 (SEM 0.04), implying that the kinetics of I gamma has a steeper temperature dependence than the kinetics of I beta. When cut fibers were cooled from 14 to 6 degrees C, I gamma in the ON segment generally became too broad to be manifested as a hump. In a cut fiber in which I gamma was manifested as a hump, the Q10 of l/tp,gamma was 2.08 and that of l/tau beta was less than 1.47. Separating the Q-V plots from cut fibers at different temperatures by method 1 showed that the proportion of Q gamma:Q beta was unaffected by temperature change. The appearance of I gamma humps at low temperatures in intact fibers but generally not in cut fibers suggests an intrinsic difference between the two fiber preparations.     

元谋新第三纪食肉动物化石的初步观察

本文对云南元谋盆地产古猿化石地点的部分食肉类化石进行了初步观察分类,认为它们的时代似应稍晚于禄丰,相当上新世早期,估计距今5-6百万年.     

广东伊绥螨属一新种（蜱螨亚纲：植绥螨科）

本文记述了植绥螨科伊绥螨属一个新种广东伊绥螨Iphiseius guangdongensis sp.nov.,对该种的形态作了详细的描述,并与它的近似种进行了比较。