一例智力低下患者7q~ 标记染色体的来源鉴定

以人类染色体显微切割、PCR技术构建的现有人类染色体特异性和染色体区带特异性探针池作为绘画探针,采用正向染色体绘画技术,结合染色体筛查方法,查明了一例7q~ 标记染色体患者的染色体附加片段来源于3q26→3qter。确定该患者的核型为46,XX,-7, der(7)t(7;3)(7pter→7q32::3q26→3qter)。应用这个策略,能够快速有效地鉴定标记染色体的来源。     

苯甲醛对果蝇视觉联想记忆的阻断

采用飞行模拟系统,以视觉模式为线索、热惩罚为负强化因子,对于在不同发育时期经受苯甲醛处理过的果蝇的视觉飞行定向条件化进行了检验。苯甲醛气味分别作用于果蝇幼虫和成虫阶段,将阻断果蝇成虫建立视觉联想记忆的能力;雌性果蝇在处女期对苯甲醛气味的接触,会阻断其子代建立视觉联想记忆,这种视觉联想记忆的能力可以通过对其子代连续３代的正常饲养而逐渐得到恢复。     

心肌电兴奋传导速度对心律失常影响的仿真研究

心电场是由心肌的电活动产生的。心肌细胞的电特性及心肌细胞间的传导关系决定了体表电位的分布及心电图的变化。心肌电兴奋传导速度则是影响心肌间兴奋传导关系的重要参数之一。由于很难通过实验方法来人为改变电兴奋传导速度,因而临床上有关该参数对心律影响的定量知识相当缺乏。本文采用真实三雏躯干模型及心脏模型,对心肌电兴奋传导速度与心律变化的关系进行定量仿真研究。结果表明,兴奋传导速度决定了整个心电图的变化,而局部普通心肌的传导速度在相当范围内变化似乎对心电图影响不明显,但传导速度超过一定范围后可能产生突变。     

用多引物PCR分析γ射线引起人外周血淋巴细胞hprt基因突变

正常人外周血用~（６０）Ｃｏ射线分别进行１～８Ｇｙ照射后,在含６－ＴＧ的培养基上克隆和筛选人淋巴细胞ｈｐｒｔ突变细胞。细胞的突变频率与γ射线的照射剂量呈正相关．获得４２个ｈｐｒｔ突变细胞株,用８对ｈｐｒｔ寡核苷酸引物进行多聚酶链反应（ＰＣＲ）从细胞粗提物中分别扩增ｈｐｒｔ各个外显子,分析突变细胞的ｈｐｒｔ基因突变,约６０％（２５／４２）的ｈｐｒｔ基因突变为基因缺失,其中１３个突变是ｈｐｒｔ基因全部缺失,而１２个是部分ｈｐｒｔ基因外显子缺失,约有４０％（１７／４２）的突变无明显的ＰＣＲ扩增变化．同时显示ｈｐｒｔ基因外显子的缺失突变与辐射剂量有关,实验结果提示,此方法有可能用于估计辐射剂量和进行辐射远后效果观察,进而揭示辐射致突的分子机理．     

海南坡鹿对生境的选择

１９８７～１９９４年,在海南省大田自然保护区及其外围地带对坡鹿的生境选择性进行了调查,发现坡鹿对自然生境有较强的选择性。对不同的生境的选择频率为：落叶季雨林生境４７．９３％;灌木草地生境３９．１４％;有刺灌丛生境１０．７２％;人工林生境２．２１％。还对各种生境进行了评价;并提出了保护生境的对策     

Cloning and characterization of CER2, an Arabidopsis gene that affects cuticular wax accumulation.

Cuticular waxes are complex mixtures of very long chain fatty acids and their derivatives that cover plant surfaces. Mutants of the ECERIFERUM2 (cer2) gene of Arabidopsis condition bright green stems and siliques, indicative of the relatively low abundance of the cuticular wax crystals that comprise the wax bloom on wild-type plants. We cloned the CER2 gene via chromosome walking. Three lines of evidence establish that the cloned sequence represents the CER2 gene: (1) this sequence is capable of complementing the cer2 mutant phenotype in transgenic plants; (2) the corresponding DNA sequence isolated from plants homozygous for the cer2-2 mutant allele contains a sequence polymorphism that generates a premature stop codon; and (3) the deduced CER2 protein sequence exhibits sequence similarity to that of a maize gene (glossy2) that also is involved in cuticular wax accumulation. The CER2 gene encodes a novel protein with a predicted mass of 47 kD. We studied the expression pattern of the CER2 gene by in situ hybridization and analysis of transgenic Arabidopsis plants carrying a CER2-beta-glucuronidase gene fusion that includes 1.0 kb immediately upstream of CER2 and 0.2 kb of CER2 coding sequences. These studies demonstrate that the CER2 gene is expressed in an organ- and tissue-specific manner; CER2 is expressed at high levels only in the epidermis of young siliques and stems. This finding is consistent with the visible phenotype associated with mutants of the CER2 gene. Hence, the 1.2-kb fragment of the CER2 gene used to construct the CER2-beta-glucuronidase gene fusion includes all of the genetic information required for the epidermis-specific accumulation of CER2 mRNA.     

水-有机溶剂两相体系中甲基单胞菌Z201催化丙烯环氧化的初步研究

Lanne于1987年提出了生物催化剂工程（Biocatalyst engimeering）和介质工程（Medium enineering）的概念^[1].有机相生物催化中溶剂的选择也是介质工程的内容之一。纯酶在有机相中的催化作用已有大量报道^[2],但对完整细胞研究甚少。本文以甲基单胞菌（Methylomonos）Z201完整细胞为生物催化剂,丙烯环氧化为指标反应,研究有机溶剂对活性的影响并对催化活性-溶剂疏水性进行了相关性分析。研究了水-十六烷两相体系中十六烷含量和搅拦速度对丙烯环氧化速度的影响和细胞的操作稳定性。     

中国Btken-Ag的特性及其杀虫毒肽的研究

苏芸金芽孢杆菌肯尼亚亚种Ag株(Bacillus thuringiensis serovar.kenyae strainAg,以下简称为Btken-Ag)是血清型H4a-4c中对棉铃虫、粘虫等多种夜蛾科害虫具有高毒力的优良品系,经生理生化、H抗原、酯酶谱、抗生谱和质粒谱等性状比较分析,与标准株肯尼亚亚种023大体相同,但其质粒谱及伴孢晶体多肽组分与023明显有别.该菌株伴孢晶体多形,其主要杀虫成分为61000多肽,经ELISA同源分析,此毒肽与同血清型中的023、7501晶体蛋白高度同源,与商品生产株H3a-3b—HD-1株部分同源,与对蚊虫高效的H14-1897及球形芽孢杆菌Ts-1无同源性.此外,对H4中10株相关株、H7-5、HD-1及1897共13株进行了对棉铃虫、粘虫及蚊虫的杀虫毒力比较测定,其中Btken-Ag的优选株H4-1及b1-4对棉铃虫的毒力高于023株及HD-1株.     

Mutations of surface residues in Anabaena vegetative and heterocyst ferredoxin that affect thermodynamic stability as determined by guanidine hydrochloride denaturation.

The stability properties of oxidized wild-type (wt) and site-directed mutants in surface residues of vegetative (Vfd) and heterocyst (Hfd) ferredoxins from Anabaena 7120 have been characterized by guanidine hydrochloride (Gdn-HCl) denaturation. For Vfd it was found that mutants E95K, E94Q, F65Y, F65W, and T48A are quite similar to wt in stability. E94K is somewhat less stable, whereas E94D, F65A, F65I, R42A, and R42H are substantially less stable than wt. R42H is a substitution found in all Hfds, and NMR comparison of the Anabaena 7120 Vfd and Hfd showed the latter to be much less stable on the basis of hydrogen exchange rates (Chae YK, Abildgaard F, Mooberry ES, Markley JL, 1994, Biochemistry 33:3287-3295); we also find this to be true with respect to Gdn-HCl denaturation. Strikingly, the Hfd mutant H42R is more stable than the wt Hfd by precisely the amount of stability lost in Vfd upon mutating R42 to H (2.0 kcal/mol). On the basis of comparison of the X-ray crystal structures of wt Anabaena Vfd and Hfd, the decreased stabilities of F65A and F65I can be ascribed to increased solvent exposure of interior hydrophobic groups. In the case of Vfd mutants E94K and E94D, the decreased stabilities may result from disruption of a hydrogen bond between the E94 and S47 side chains. The instability of the R42 mutants is also most probably due to decreased hydrogen bonding capabilities.(ABSTRACT TRUNCATED AT 250 WORDS)