Multiple genotypes of mitochondrial DNA within a horse population from a small region in Yunnan province of China

mtDNA genotypes of six domestic horses (three adult short horses whose heights are under 1 m and three common domestic horses) from a small region of 15 km² in Malipo county of Yunnan province of China were investigated by the technique of restriction fragment length polymorphism (RFLP) with 16 restriction endonucleases which recognize 6-bp sequences. An average of 56 fragments for an individual was obtained. Unlike other domestic animals, this population of horses exhibits high mtDNA genetic diversity. Each of the six horses has a specific mtDNA genotype showing a pattern of multiple maternal origins, as suggested by fossil and literature records. We think the population of horses is an amazing seed-resource pool of horses and hence deserves to be paid more attention from the view of conservation genetics. However, it is also remarkable that we did not find any typical mtDNA genetic markers which would discriminate between short horses and common domestic horses.     

Intraspecific cleaning behaviour in Cyprinus carpio in aquaria

Intraspecific cleaning behaviour of diseased juvenile Cyprinus carpio L, in experimental tanks in Wuxi, China has been observed and is described.     

A Suppressor of a Mating-Type Limited Zygotic Lethal Allele Also Suppresses Uniparental Chloroplast Gene Transmission in Chlamydomonas Monoica

Uniparental inheritance of Chlamydomonas chloroplast genes is thought to involve modification of maternal (mt(+)) chloroplast genomes to protect against a nuclease that is activated after gamete fusion. The mating-type limited mtl-1 mutant strain of Chlamydomonas monoica is unable to protect mt(+)-derived chloroplast DNA. Zygotes homozygous for mtl-1 lose all chloroplast DNA and fail to germinate. We have selected for suppression of this zygote-specific lethality, and have obtained 20 mutant strains that produce viable homozygotes despite the continued presence of the mtl-1 allele. Genetic analysis indicates that the suppressor mutations are all recessive alleles at a single locus (sup-1) which is unlinked to mtl-1. Crosses between sup-1 strains carrying distinctive chloroplast antibiotic resistance markers also show predominantly biparental chloroplast gene transmission. Chloroplast nucleoids of both parental origins (stained with the DNA-specific fluorochrome, DAPI) are retained in the zygotes homozygous for sup-1. The data are compatible with the idea that the sup-1 (suppressor of uniparental inheritance) locus may encode a chloroplast DNA nuclease that is expressed from both parental genomes.     

Reaction mechanism of isomaltooligosaccharides synthesis by α-glucosidase fromAspergillus carbonarious

Summary An -glucosidase fromAspergillus carbonarious CCRC 30414 was employed for investigating the enzymatic synthesis of isomaltooligosaccharides from maltose. The enzyme transferred a glucose unit from the nonreducing end of maltose and other -linked glucosyl oligosaccharides to glucose and other glucosyl oligosaccharides which function as accepting co-substrates. The transfer of a glucose unit occurs most frequently to the 6-OH position of the nonreducing end of acceptor, but transfer to 4-OH position also occurs. Treatment of 30 % (w/v) maltose with the enzyme under optimum conditions afforded more than 50% isomaltooligosaccharides.     

Specificity and function of monoclonal antibodies directed against Ewing sarcoma cells

A selection of 16 monoclonal antibodies has been produced against a fresh Ewing's sarcoma (ES) tumor mixed with a permanent ES cell line. The majority of antibodies identify an 80-kDa molecule, which is not detected on healthy tissues except on certain cultured monocytes. One antibody recognize the CD2 ligand MIC2 and 2 antibodies (numbers 13 and 16) define a higher-molecular-mass antigen. Antibody 16 is also expressed on mesenchymal fibroblasts of bone marrow or fetal origin. Tumorspecific antigen expression is potentially linked to the chromosome 22 abnormality decribed in Ewing's sarcoma.     

百合离体生殖细胞骨架的扫描电镜观察

从百合的花粉管分离出来的生殖细胞,经表面活化剂Ｔｒｉｔｏｎ Ｘ－１００ 及核糖核酸酶、硫酸铵离析处理。离析后的细胞经临界点干燥,扫描电镜观察显示：在离体生殖细胞的胞质内有一个非常复杂的支架网络系统。这一网络系统有内外两层：外层（靠近细胞膜）网络结构紧密,纤维束粗长;内层（靠近核）网络结构疏松,纤维束短细。一些间接证据显示,这一支架网络系统可能为微管骨架     

大蒜中期染色体内的核糖核蛋白物质

研究了大蒜（Ａｌｌｉｕｍ ｓａｔｉｖｕｍ Ｌ．）中期染色体的超微结构和ＲＮＰ物质。常规染色表明,大部分染色体内部有低电子密度区,有的染色体中低电子密度区域较大而似孔洞。银染结果也证明了有大小不等的孔洞存在。Ｂｅｒｎｈａｒｄ 染色显示,在染色体周边和染色体内部都有ＲＮＰ分布。用ＮａＯＨ 处理证明了Ｂｅｒｎｈａｒｄ 染色法所显示的深染区确实含有ＲＮＡ。ＲＮＰ量的多少与ＥＤＴＡ 的分化时间呈负相关     

横纹肌肌原纤维的第三肌丝──肌联蛋白

实验研究证明,在动物横纹肌肌原纤维中,除包含有粗肌丝、细肌丝外,还有纤肌丝的存在,肌联蛋白（肌巨蛋白）是具有挠性的线状蛋白质,分子量为3000 000,长度约为0.9μm,跨越肌原纤维的M－线和Z－线,形成纤肌丝.其生理功能是在粗肌丝装配中具有分子模板作用,并将粗肌丝稳定于肌原纤维肌小节中央以及可参与肌球蛋白活性的调节.     

AST同工酶的琼脂糖凝胶电泳NBT显色法

分布于细胞内线粒体及细胞质中的天门冬氨酸氨基转移酶(AST·EC·2·6·1·1)是人血清中含有的两种同工酶,分别称为AST-m和AST-c同工酶.AST-c电泳迁移率介于血清α-球蛋白与β-球蛋白之间.AST-m电泳迁移率相似于γ-球蛋白,琼脂糖凝胶电泳固蓝B染色法对m-AST检出率较低.用NBT显色法则可得到较好效果.     

大血藤科植物的分类学研究

作者对大血藤科植物的花性、叶片内部结构形态、花粉形态、染色体核型及过氧化物酶和脂酶同工酶进行了比较研究,结果表明：１）大血藤科植物外形上的两性花,其雄蕊的形态退化、花药始终不开裂,为功能上的雌花,因此其花为单性,同株,同序或异序;１２）首次指出大血藤属植物的染色体数为２ｎ＝２ｘ＝２２,属小型染色体,与木通科植物２ｎ＝２ｘ＝３２、３０、２８的染色体数明显不同,支持Ｓｔａｐｆ（１９２６）将其从木通科分出另立为科的观点;３）单叶和复叶可出现于同一植株上,而且在叶片内部结构、花粉形态、染色体核型、过氧化物酶及脂酶同工酶等性状上,大血藤与单叶血滕间均无实质性的差异,因此将单叶血藤归并于大血藤中。