Studies on the origin and evolution of tupai in Thailand

1.筛选出PA、Alb、Pi、Gc、Tf和慢巨球蛋白6个血浆基因座，其中PA、Alb、Gc和Tf基因座表现出多态性。这些基因座的基因频率值在不同地点有波动，普通兔类血浆蛋白的遗传变异性高于灵长类。2.为了研究图牌种内和种间的遗传变异，特别是探讨东方动物区系中两个亚区的动物地理学分类意义，对图牌种的线粒体DNA进行了限制性片段长度多态性分析。印度支那和马来半岛两个亚区种群间mtDNA的分化程度较大，提示两个亚区的动物地理区分意义。3.对普通树鼩 MHC Ⅱ类基因cDNA进行了分子生物学分析，为研究哺乳动物免疫系统的进化提供了重要信息。克隆CL1、CL2和CL3分别与HLA Ⅱ类DQ、DR和DP区有较高的同源性。因此，在普通树鼩中可能存在DP、DQ和DR三种亚型的HLA Ⅱ类分子。4.普通树鼩颅腔静脉图尼卡中膜心肌细胞层发达。肌层分布于右心房至锁骨下静脉根部。由于普通树鼩所属的Scandentia目是哺乳动物目的一个原始类群，因此颅腔静脉中的肌肉系统的出现被认为是哺乳动物身体的基本结构。

1.Six plasma loci, that is, PA,Alb, Pi, Gc, Tf and slow macroglobulin were screened, and PA,Alb, Gc and Tf loci showed polymorphism. The values of gene frequency of these loci was fluctuated in each locality, and genetic variability of plasma proteins of common tupai was higher than that of primate species. It is estimated that the degree of gene disversions within and between each locality is low.2.Restriction fragment length polymorphisms of mitochondrial DNA(mtDNA) were examined for the common tupai in order to investigate genetic variations within and between local populations, especially to test the significance of zoogeographical classification of twosubregions in the oriental faunal region. The degree of mtDNA differentiation was large between those populations of the Indochina region and the Malay Peninsula region, suggesting the significance of zoogeographical discrimination of two subregions in this species.3.The molecular analysis of the MHC class II cDNA of the common tree shrew, which might provide important informations on the evolution of the immune system in mammals, was carried out. Three clones (CL1, CL2 and CL3) with different nucleotide sequence were obtained and showed high homology indices to HLA class II DQ,DR and DP regions, respectively. Thus three isotypic forms of class II molecules, DP,DQ and DR,might exist in common tupai like in HLA system.4.The common tree shrew had well-developed cardiac myocyte layrs in the tunica media of the cranial vena cava. Musculature was distributed from the right atrium to the root of the subclavian vein. Because the Order Scandentia to which the common tree shrew belongs is a primitive group of mammalian orders, occurence of musculature in the cranial vena cava is suggested to have developed as a basic structure of the mammalian body.