人工染色体研究进展

细菌人工染色体（ＢＡＣｓ）、噬菌体Ｐ１衍生的人工染色体（ＢＡＣｓ）和酵母人工染色体（ＹＡＣｓ）是近年发展起来的ＤＮＡ克隆新技术。着重介绍了ＹＡＣｓ作为转移大分子外源ＤＮＡ的载体，在生物基因组分析，基因的结构与功能、表达与调控、定位与分离以及遗传病的基固治疗等研究领域的应用。比较了ＢＡＣｓ、ＰＡＣｓ和ＹＡＣｓ的主要特点。对哺乳动物人工染色体的研究情况也作了简要介绍。     

Nearctic–Palaearctic relationships of black flies (Diptera: Simuliidae): chromosomal and morphological evidence for the Prosimulium magnum species group in Japan

The banding patterns of the polytene chromosomes of Prosimulium yezoense Shiraki from Japan are resolved relative to the standard map for the genus Prosimulium, revealing two unique fixed inversions and novel autosomal and sex-linked rearrangements. Diagnostic chromosomal and morphological criteria demonstrate that P. yezoense is a member of the Prosimulium magnum group. The species is transferred, with three additional species – P. apoina Ono, P. karibaense Ono, and P. sarurense Ono – from the Prosimulium hirtipes group to the P. magnum group, representing the first geographic record of the group outside North America. The P. magnum group is one of only a few insect taxa, and one of only two simuliid taxa, distributed exclusively in Japan and the Nearctic region.     

An overview of factors influencing sex determination and gonadal development in birds

The morphological development of the embryonic gonads is very similar in birds and mammals, and recent evidence suggests that the genes involved in this process are conserved between these classes of vertebrates. The genetic mechanism by which sex is determined in birds remains to be elucidated, although recent studies have reinforced the contention that steroids may play an important role in the structural development of the testes and ovaries in birds. So far, few genes have been assigned to the avian sex chromosomes, but it is known that the Z and W chromosomes do not share significant homology with the mammalian X and Y chromosomes. The commercial importance of poultry breeding has motivated considerable investment in developing physical and genetic maps of the chicken genome. These efforts, in combination with modern molecular approaches to analyzing gene expression, should help to elucidate the sex-determining mechanism in birds in the near future.     

苦荞麦染色体的加倍研究

应用秋水仙素和二甲基亚砜混合液对中国西南地区的三种苦荞麦品种进行染色体加倍,获得了同源四倍苦荞新品系.与原种相比,同源四倍苦荞新品系具有发达的根系、较大的籽粒和高大植株,其产量得到明显提高.新品系的蛋白质、氨基酸、维生素经及其他药用成分的含量也有明显的提高.此外,新品系有较高的接实率,能稳定遗传,具有较强的抗逆能力.     

乐清湾泥蚶Tegillarca granosa (Linnaeus)核型的初步研究

利用胚胎细胞做成的染色体制片,对乐清湾泥蚶染色体进行了分析。结果表明乐清湾泥蚶核型为2N=38,32m 6sm,NF=76。     

制备分散良好的植物细胞染色体标本的初步试验

本文介绍了用低渗处理技术制备分散良好的洋葱根尖细胞染色体标本的方法。     

用遗传算法求解GTSP的编码改进

在遗传算法的过程中,变异概率是很低的,相对交叉算子对于影响染色体的多样性更为重要。针对基于广义染色体求解GTSP的遗传算法,提出一种二进制与十进制混合编码,改进了交叉算子,具有更强的搜索能力。测试证明算法改进是有效的。     

黄瓜根尖体细胞同源染色体的联合现象

对黄瓜根尖体细胞有丝分裂过程中同源染色体的联合现象进行了研究。结果发现，黄瓜体细胞有丝分裂前期末，7对同源染色体以体细胞联合的方式粘附于核仁周围，随着核仁解体，细胞分裂才进入前中期。这一实验结果表明，黄瓜体细胞中存在的同源染色体间的联合现象是前期核仁消失前一个特定的阶段，是一个正常的生物学现象。