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排序方式: 共有48条查询结果,搜索用时 31 毫秒
41.
《Journal of Natural History》2012,46(23-24):1467-1475
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. 相似文献
42.
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. 相似文献
43.
苦荞麦染色体的加倍研究 总被引:1,自引:0,他引:1
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. 相似文献
44.
45.
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。 相似文献
46.
Quantitative trait loci (QTLs) for quality traits related to protein and starch in wheat 总被引:2,自引:0,他引:2
Haiyan Sun Jianhua Lü Yuding Fan Yan Zhao Fanmei Kong Rijun Li Honggang Wang Sishen Li 《自然科学进展(英文版)》2008,18(7):825-832
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D. 相似文献
47.
乐清湾泥蚶Tegillarca granosa (Linnaeus)核型的初步研究 总被引:2,自引:0,他引:2
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。 相似文献
48.
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。 相似文献