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重复、缺失、倒位和易位在家蚕中都有发生,其中易位在家蚕育种具有重要的实用价值。易位能改变基因连锁群,家蚕育种中正是利用这一遗传作用,进行限性品种培育的。家蚕的性别决定为ZW型,雌蚕性染色体为ZW,雄蚕性染色体为ZZ,W染色体具有完全决定雌性的功能,因此,把常染色体上带有的标记基因如普斑(+~p)片断易位到W染色体上就能得到普斑和雌蚕完全连锁的斑纹限性,这样,不需看蚕的生殖腺,只根据斑纹的有无即可进行雌雄鉴别。由于限性品种的推广在生产上具有重要的意义,因此,自田岛1940年首次获得斑纹限性以来,从事W性染色体易位和限性品种培育的研究很多,而且取得了很大成果。通过辐射已有5条常染色体和W性染色体之间发生了易位,易位涉及的标记基因位点有9个,获得了17个不同遗传基因的限性易位系。日本自1967年育出实用化斑纹限性品种中131×
Repeats, deletions, inversions and translocations all occur in silkworms, of which translocation has important practical value in silkworm breeding. Translocation can change the genetic linkage group, silkworm breeding is the use of this genetic role, to cultivate limited varieties. The sex determination of silkworm is ZW type, the female sex chromosome is ZW, the male sex chromosome is ZZ, and the W chromosome has the function of completely determining the female. Therefore, the marker genes on autosomes such as Pu (+ ~ p) Fragment translocation to the W chromosome will be able to get the general spot and female silkworm completely linked to the stripe limit, so that without having to look at silkworm gonads, only according to the presence of plaques can identify male and female. Due to the importance of the promotion of limited varieties in production, many studies have been conducted on the translocation of W sex chromosomes and restriction cultivars since the island was first demarcated in 1940, and great achievements have been made. By translocating 5 autosomes and W sex chromosomes, there are 9 marker loci involved in translocation, and 17 restriction translocations of different genes were obtained. Japan since 1967 bred limited varieties of practical 131 ×