ApoB gene nonsense and splicing mutations in a compound heterozygote for familial hypobetalipoproteinemia.

Two novel apoB gene mutations were identified in a patient (CM) with phenotypic homozygous hypobetalipoproteinemia. Haplotype analysis of the apoB alleles from this patient and his family members revealed him to be a genetic compound for the disease. In contrast to previous studies of other hypobetalipoproteinemic patients, no clues existed as to where in the apoB gene the molecular defects resided. Therefore, it was necessary to characterize the apoB genes of the patient by sequence analysis. The apoB gene contains 29 exons and is 43 kb in length. The gene encodes a 14.1 kb mRNA and a 4563 amino acid protein. Both apoB alleles from the patient were cloned via 26 sets of polymerase chain reactions (PCR). These clones contained a total of approximately 24 kb of apoB gene sequence, including regions 5' and 3' to the coding region, 29 exons, and the intron/exon junctions. Complete DNA sequence analysis of these clones showed that each apoB allele had a mutation. In the paternal apoB allele, there was a splicing mutation. The first base of the dinucleotide consensus sequence (GT) in the 5' splice donor site in intron 5 was replaced by a T. It is likely that this base substitution interferes with proper splicing and results in the observed absence of plasma apoB. In the maternal apoB allele, there was a nonsense mutation. The first base of the Arg codon (CGA) at residue 412 in exon 10 was replaced by a T, resulting in a termination codon (TGA). The nonsense mutation is likely to terminate translation after residue 411 resulting in a severely truncated protein only 9% of the length of B-100.(ABSTRACT TRUNCATED AT 250 WORDS)     

Crystallographic analysis of the neurophysin-oxytocin complex. A preliminary report

Single crystals of a bovine neurophysin II-oxytocin complex have been obtained using (NH4)2SO4 as the precipitating agent. The crystals diffract to at least 2.7 A resolution, belong to Laue group 4/mmm and exhibit systematic absences consistent with either space group P4(1)2(1)2 or P4(3)2(1)2. The cell dimensions are a = b = 69.07 A and c = 113.26 A. The crystals contain one neurophysin-oxytocin dimer per asymmetric unit. Based on a Vm of 2.9 A3/Da, the solvent content is calculated to be 58%. Chromatographic analysis of the dissolved crystals suggests the presence of three oxytocin molecules per neurophysin dimer.     

溶液流动对等电溶菌酶晶体生长的影响

本文对等温自由生长和强制性溶液生长的等电溶菌酶的晶体形态进行了研究,发现这些形态变化与溶液相的流动密切相关,指出生物晶体生长停止是由于生长晶体周围的溶质贫乏造成的;通过某些手段减薄或消除这一溶质贫乏区,就可以保证晶体的持续生长。本文的研究对改善大尺寸晶体的生长提供了一条途径。     

准噶尔盆地荒漠生物类群与环境的关系

对荒漠生态系统的研究,近期在我国乃至全球均极为活跃。由于开发的需要和全球沙漠化威胁日趋严重,引起有关人士的关注。就新疆而言,解放前虽有一些学者进行过研究,但仅限于某些方面,直到50年代后期展开大规模综合考察以来,对新疆的荒漠自然条件才有较全面认识。作者近年的研究过程,注意到此区生物类群与环境存在较特殊关系,     

建立生态经济型橡胶园橡胶咖啡间作模式

一、云南植胶区的自然地理条件云南橡胶种植区位于云南高原南部,北纬20°09′—24°59′,东经93°31′—105°08′,海拔100—1000m之间的热带季风地区。包括文山、红河、思茅、西双版纳、临沧和德宏地区     

茶园冬季乔木落叶的分解和矿质元素释放

在我国南方存在着一种传统植茶方式——茶林复合生态系统,近年来人们已逐步认识到它在维持土壤肥力,抗御自然灾害和保证茶叶内质特性等方面的作用,然而对冬季乔木落叶分解和矿质元素释放的作用尚无报道。本文是对安徽省黄山市休宁县茶树-乌桕复合园和茶树-板栗复合园的冬季乔木落叶分解的研究,为全面认识茶林复合生态系统的性质提供依据。     

造血细胞活力冷冻损伤的可恢复性

人骨髓冻存后其造血祖细胞活力有一定程度下降,本研究对这种下降的可逆性作了初步观察。结果发现,用双层法和单层法作CFU-GM培养时,未冻存骨髓集落产率相近,冻存骨髓双层法的CFU-GM产率高于单层法。骨髓细胞用20％FM-CM、PHA-LYCM、PHA-PMCM预孵育2h后,分别测定其CFU-GM、BFU-E与CFU-Mix,发现这种孵育过程对未冻存骨髓的集落产率无明显影响,而冻存骨髓的集落产率在孵育后可升高(GEMmeg除外)。说明骨髓造血祖细胞对冻存的损伤反应不均一,部分受损细胞在一定条件下可以恢复其增殖活力。这对于用冻存骨髓作骨髓移植可能有一定意义。     

籼、粳杂种的“随体丢失”

1985—1986,观察籼、粳及籼,粳F_1杂种终变期核仁染色体数,籼为2个二价核仁染色体,粳为1个二价核仁染色体,籼、粳F_1杂种核仁染色体数与父本水稻的核仁染色体数相同。由此,讨论了“随体丢失”在水稻育种,粳稻起源及遗传学方面的意义。     

病毒唑及其与干扰素联合对慢性乙型肝炎抗病毒效应观察

本文报道了病毒唑及其与干扰素联合对23例慢乙肝近、远期抗病毒效应观察结果,并与12例未经抗病毒治疗的慢乙肝作对照(Ⅲ组),其中病毒唑与干扰素联合组(I组)12例,病毒唑组(Ⅱ组)11例。近期HBeAg、DNAP及HBV·DNA阴转率,I组分别为(41.6％、55.5％及28.s％,Ⅱ组45.4％、100％及33.3％,Ⅲ组8.3％、16.6％及8.3％。远期HBeAg及DNAP阴转率在I组分别为70％、83.7％。Ⅱ组60％、100％,Ⅲ组8.3％,50％。综合抗病毒效应,近期有效率在I、Ⅱ、Ⅲ组分别为50％、72.7％及16.6％。远期则分别为70％、55.5％及8.3％。无一例出现毒副反应。均完成疗程。上述结果提示病毒唑及其与干扰素联合对慢乙肝均有一定抗病毒效应,联合应用并不优于单一用药,但毒副反应也未见加重,而且病毒唑药源较方便,使用较安全,值得进一步研究。     

大鼠肾脏组织cDNA文库的制备和葡萄糖转运蛋白cDNA克隆的筛选

 大鼠的肾脏组织经匀浆后,提取纯化总RNA和mRNA合成cDNA,进行甲基化,加人工接头,最后连入载体(λgt11)和外壳蛋白包装步骤制成肾脏组织的cDNA文库。插入载体的cDNA长度为0.5kb到8kb之间。经反复稀释,测定出该文库的效价为1.5×10~7pfu/mL。