Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum

We have examined the structure and chromatin organization of telomeres in Nicotiana tabacum. In tobacco the blocks of simple telomeric repeats (TTTAGGG)_n are many times larger than in other plants, e.g., Arabidopsis thatiana or tomato. They are resolved as multiple fragments 60–160 kb in size (in most cases 90–130 kb) on pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested DNA. The major subtelomeric repeat of the HRS60 family forms large homogeneous blocks of a basic 180 by motif having comparable lengths. Micrococcal nuclease (MNase) cleaves tobacco telomeric chromatin into subunits with a short repeat length of 157±5 bp; the subtelomeric heterochromatin characterized by tandemly repeated sequences of the HRS60 family is cut by MNase with a 180 by periodicity. The monomeric and dimeric particles of telomeric and subtelomeric chromatin differ in sensitivity to MNase treatment: the telomeric particles are readily digested, producing ladders with a periodicity of 7 bp, while the subtelomeric particles appear to be rather resistant to intranucleosomal cleavage. The results presented show apparent similarities in the organization of telomeric chromatin in higher plants and mammals.     

应用流式细胞仪研究抗IL-8单抗对IL-8激活人颗粒细胞活力的中和作用(英文)

以IL-8免疫的BALB/C小鼠脾细胞与Sp2/0或653小鼠骨髓瘤细胞融合构建了淋巴细胞杂交瘤克隆I8-S2和I8-63。ELISA叠加试验(ELISA Additivity Test)表明这两杂交瘤克隆分泌的单抗分别识别IL-8分子的不同表位。IL-8能激活人颗粒细胞,引起细胞内Ca~(2 )浓度([Ca~(2 )]_i)上升。通过流式细胞仪分析[Ca~(2 )]_i的变化,发现两个克隆单抗对IL8激活细胞的活力具有不同的中和作用。克隆I8-S2具有很强的中和作用,而克隆18-63则不然。上述结果提示IL-8的激活细胞活力局限于该分子的某表位。     

东北地区生态环境中的Se及其生态效应

对东北地区不同环境要素Ｓｅ的分布与转化规律的研究表明,基岩、土壤、粮食和动物毛Ｓｅ含量分别为０．１２、０．１５０－０．５４０、０．００９６－０．０７６５和０．０４０５－０．１４１４μｇ．ｇ＾－１;城市和农村儿童发Ｓｅ含量为０．４６０和０．１８２μｇ．ｇ＾－１。根据不同要素Ｓｅ含量和生态效应,可将该区分为Ｓｅ适宜区、缺乏区和过渡区３个１级区,每个１级区又分为高Ｓｅ源区的低Ｓｅ源区。     

src-specific immunity in inbred chickens bearing v-src DNA- and RSV-induced tumors

Serological data identify a single major histocompatibility complex (MHC) class I locus in cattle. Molecular data, however, demonstrate the presence of at least two cattle MHC (BoLA) class I loci. To investigate the number of transcribed BoLA class I genes, we amplified cattle cDNA by using a single MHC class I-specific primer that hybridized to a conserved region of exon 4 and a non-specific 3 primer. Six BoLA class I cDNAs have been cloned and sequenced from a Bos taurus bull heterozygous for BoLA class I serological antigens, demonstrating the presence of a minimum of three loci. Sequence comparisons suggested that one of these cDNAs may be an unexpressed allele or the product of a nonclassical locus.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers U01186 and U01187.     

The genetic characterisation of novel multi-addition doubled haploid lines derived from triticale x wheat hybrids

Two novel 46-chromosome doubled haploid lines, W66 and M17, derived from separate hexaploid triticale x bread wheat crosses, were characterised using cytological and biochemical markers. Both lines were shown to be relatively stable cytologically, over 11 and 8 generations of selfing, respectively. By examining mitotic and meiotic chromosomes, the stabilities of the two lines were shown to be similar with frequencies of 2n=46 in 74.2–85.5% of cells. However, over selfed generations, the rye chromosomes were shown to have lost some of their heterochromatin, which made it difficult to establish their continued presence using cytological techniques, such as C-banding alone. Cytological evidence from pairing studies, C-banding, and fluorescence in-situ hybridization, showed that both M17 and W66 are wheat/rye multi-addition lines with rye chromosome constitutions of 1R+6R, and 1R+4R, respectively. These conclusions were confirmed by isozyme and storage-protein analysis.     

油菜菌核病危害损失的初步研究

本文就油菜菌核病病情、发病期及发病部位与油菜产量损失的相互关系进行了模似研究。结果表明：病斑绕茎度是影响产量的主要因素,其大小与产量损失成正相关,而病斑纵向长度与产量损失无明显相关性;发病期不同产量差异显著,以初花期发病产量损失最重,发病期与产量损失线性相关,可利用线性回归方程对产量损失进行预测;主茎发病部位愈近基部,枝条发病部位愈趋于主茎,单株产量损失率愈高。     

黄桃罐头产品质量Fuzzy综合鉴评

本文根据FuzzZ数学理论,运用多级模型的综合评判法,对国内20种黄桃罐头产品质量进行了优劣鉴评。并将其划分为一、二、三、四4个等级。从而为罐头产品质量鉴评,准确地汰劣遴优提供新方法。     

物种保护信息管理系统的开发应用

在英文物种、生境和保护区管理系（MASS 3．1）的基础上,研究并改编完成了其中文系统软件包（CMASS 2．0）,并用此中文系统软件包建立了中国自然保护区信息库、中国保护动物信息库、中国濒危动物信息库、中国兽类信息库、中国鸟类信息库,这些库的建立对我国野生动物保护具有重要意义。     

人IL-6和TNF突变体重组融合蛋白表达质粒的构建及在大肠杆菌中的表达

本文利用PCR技术,对人肿瘤坏死因子α(hTNFα)基因进行了改造,并将其与人白细胞介素-6(hIL-6)成熟肽编码区cDNA进行融合,构建了5′IL-6-TNF△融合蛋白的表达质粒pBVIL6-TNFA△。DNA序列分析证明,PCR扩增片段核苷酸序列与引物设计序列及相应的cDNA序列完全一致;重组子用限制性内切酶酶切鉴定,含有正确的IL6-TNF△融合cDNA片段;表达产物经SDS-聚丙烯酰胺凝胶电泳,分子量约为37kD,与预计的相符合;生物学活性分析初步表明,该融合蛋白具有抗肿瘤活性。