Genetic analysis of autoimmune type 1 diabetes mellitus in mice.

Two genes, Idd-3 and Idd-4, that influence the onset of autoimmune type 1 diabetes in the nonobese diabetic mouse have been located on chromosomes 3 and 11, outside the chromosome 17 major histocompatibility complex. A genetic map of the mouse genome, analysed using the polymerase chain reaction, has been assembled specifically for the study. On the basis of comparative maps of the mouse and human genomes, the homologue of Idd-3 may reside on human chromosomes 1 or 4 and Idd-4 on chromosome 17.     

Genetic defect in secretion of complement C5 in mice.

A genetic deficiency of the fifth (C5) component of complement1-3, a serum glycoprotein of molecular weight (MW) 220,000 (ref. 4), has been found in 39% of inbred strains of mice3. Sera of deficient mice lack detectable C5 activity and protein2,3. In addition deficient mice produce antibody to mouse C5 when injected with sera from C5 sufficient (normal) strains. Levy et al.5 showed that somatic cell hybrids between C5 deficient (B10.D2/old line) macrophages and either C5 sufficient (B10.D2/new line) mouse kidney or chicken erythroblasts secreted haemolytically active mouse C5 in vitro. Several possible molecular mechanisms to account for the findings were considered, but insufficient direct data were available to choose among them. We recently reported that mouse (CD.1 strain) peritoneal cells in culture synthesise and secrete a single chain precursor, pro-C5 (MW approximately 210,000), of the two-chain (alpha chain, 125,000 and beta chain 83,000 MW) C5 protein6. Radiolabelled precursor C5 was contained within the cells and was secreted into the tissue culture media. Using similar methods, we now find that C5 deficiency in each of five different mouse strains (AKR, SWR, DBA/2J8 A/HeJ and B10.D2/old line) is due to a failure in secretion of C5 protein and not to a failure in biosynthesis of pro-C5.     

Endogenous mammary tumour virus DNA varies among wild mice and segregates during inbreeding.

Proviruses of the mouse mammary tumour virus (MMTV) endogenous to normal mice can be identified by molecular hybridisation and distinguished using restriction endonucleases. Feral mice display marked heterogeneity with respect to the number of copies and the sites of insertion of endogenous MMTV-specific DNA, with occasional mice apparently free of MMTV DNA. Several different MMTV proviruses present in laboratory mice have segregated like stable, independent genetic elements during the inbreeding which followed a cross between Bagg albino and DBA mice 60 years ago. The results favour the hypothesis that endogenous proviruses have been established by multiple, independent infections of germ cells rather than by somatic mutation of ancestral proviruses or of cellular genes.     

Genetic variations of glycinin subunit genes among cultivated and wild type soybean species

Glycinin is a predominant storage protein in most soybean accessions. It is a hexamer constituted by five major subunits, which can be classified into two groups. Group I contains G1, G2 and G3, and Group II contains G4 and G5. The genes encoding these subunits have been designated from Gy1 to Gy5 , respectively. In the present study, Gy1 genomic fragments were cloned from wild accessions of subgenera Glycine glycine, Glycine soja and a cultivar of Glycine max . Their sequences and the deduced amino acid sequences were compared. The residues critical for assembling of G1 subunits from the wild perennial accession were conservative. The Gy4 fragments were cloned from two wild perennial accessions and compared with that from subgenus Soja . The intron 3 of Gy4 had abundant variations between the subgenera G. soja and G. glycine as well as within the subgenus G. glycine. Abundant variations existed in the disordered regions 3 and 4 of G4 subunits from two wild perennial accessions. The genomic organization of glycinin genes was analyzed in 19 accessions from subgenera Soja and Glycine . The hybridization patterns were identical among the accessions of subgenus Soja. On the contrary, abundant polymorphisms existed between the accessions from subgenus Glycine . These results indicated that glycinin genes have high degree of conservation within subgenus Soja but more variations within subgenus Glycine .     

Genetic variations of glycinin subunit genes among cultivated and wild type soybean species

Glycinin is a predominant storage protein in most soybean accessions. It is a hexamer constituted by five major subunits, which can be classified into two groups. Group I contains G1, G2 and G3, and Group II contains G4 and GS. The genes encoding these subunits have been designated from Gyl to Gy5, respectively. In the present study, Gyl genomic fragments were cloned from wild accessions of subgenera Glycine glycine, Glycine soja and a cultivar of Glycine max. Their sequences and the deduced amino acid sequences were compared. The residues critical for assembling of G1 subunits from the wild perennial accession were conservative. The Gy4 fragments were cloned from two wild perennial accessions and compared with that from subgenus Soja. The intron 3 of Gy4 had abundant variations between the subgenera G. soja and G. glycine as well as within the subgenus G. glycine. Abundant variations existed in the disordered regions 3 and 4 of G4 subunits from two wild perennial accessions. The genomic organization of glycinin genes was analyzed in 19 accessions from subgenera Soja and Glycine. The hybridization patterns were identical among the accessions of subgenus Soja. On the contrary, abundant polymorphisms existed between the accessions from subgenus Glycine. These results indicated that glycinin genes have high degree of conservation within subgenus Soja but more variations within subgenus Glycine.     

云南中部地区几种常见野菜的调查研究

文章对滇中地区6种常见野菜，鱼腥草，蕨菜，大白花杜鹃，荠菜，灰条菜，水蕨菜进行了调查研究，通过民间调查，资料收集，对这些野菜的食用方法，化学及营养成分，药理及毒副作用，开发利用，人工栽培等7个方面进行了研究，为人们的开发利用提出了一些建议。     

野生垂穗披碱草种质的醇溶蛋白遗传多样性研究

用酸性聚丙烯酰胺凝胶电泳（A-PAGE）对采集自中国青海、西藏、四川、甘肃、新疆的64份垂穗披碱草（Elymus nutans Griseb．）材料进行了多态性分析,结果表明：（1）供试材料共分离出42条带纹,多态率达90．48%,材料间遗传相似系数（GS）变化范围为0．320～1．000,平均GS值为0．631．说明供试垂穗披碱草材料具有较为丰富的醇溶蛋白遗传多样性;（2）对所有材料的聚类分析和主向量分析（PCoA）发现,在GS值为0．59的水平上供试材料可聚成六个类群,大部分来自相同或相似生态地理环境的材料聚为一类,即供试材料的醇溶蛋白图谱类型与材料的生态地理环境具有一定的相关性．     

Proviral sequences of baboon endogenous type C RNA virus in DNA of human leukaemic tissues.

Hybridisation of RNA from a baboon endogenous type C RNA virus to DNA from tissues of leukaemic patients indicates that a virus of this type is horizontally transmitted among humans. DNA from several patients with leukaemia hybridised 70% of the hybridisable RNA from baboon endogenous type C RNA virus (BaEV) and yielded hybrids of high tm, whereas DNA from normal human tissues hybridised only 23% of the BaEV RNA, and the tm of these hybrids was lower.     

Genetic enhancement of learning and memory in mice.

Hebb's rule (1949) states that learning and memory are based on modifications of synaptic strength among neurons that are simultaneously active. This implies that enhanced synaptic coincidence detection would lead to better learning and memory. If the NMDA (N-methyl-D-aspartate) receptor, a synaptic coincidence detector, acts as a graded switch for memory formation, enhanced signal detection by NMDA receptors should enhance learning and memory. Here we show that overexpression of NMDA receptor 2B (NR2B) in the forebrains of transgenic mice leads to enhanced activation of NMDA receptors, facilitating synaptic potentiation in response to stimulation at 10-100 Hz. These mice exhibit superior ability in learning and memory in various behavioural tasks, showing that NR2B is critical in gating the age-dependent threshold for plasticity and memory formation. NMDA-receptor-dependent modifications of synaptic efficacy, therefore, represent a unifying mechanism for associative learning and memory. Our results suggest that genetic enhancement of mental and cognitive attributes such as intelligence and memory in mammals is feasible.