家蚕の性染色体に関する育種遺伝学的研究 : I.W染色体の品種的差異に就いての検討(第1報)

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Genetical results hitherto obtai.ned have proved W-chromosome deternl;ined alone the famale sex in silkworm (Hashimoto 1933. Tazima 1944) . Even if the sexual characters are excluded, various differences exist in regard to the quantit.ative characters, among which include many available ones for silkworrn bteeding, between male and female. Silce vchromosore is responsible to the sex determination, it should bc also tb the sexual difference in quanti'ca+Live characters. Here, The problems will arise concerning with the capacity of W-chro-mosome to influence on the,m, especially frorn the standpoint of thremmatological view whether raciaJ difference of it will be existed or not. This experiment was carried out in order L-o eluci-date the point tbove men:tioned. W, chronl:osorle of two races, OIO and 72, were chooen to ntaterials. The former is a europian univoltin014s race characterized with its remarkable abu. ndance of cocoon layer, weight of it almost turns the scale 8 at 70 dg in average' number of 25 batches and the la'L'Ler rather a meagre one, 37 og. To the F_1 hybrids of OIO( Q+ ) x72( ~ ) and 72( ~ ) x OIO(~), backcross mating was continuously re-peated by the same nl:ale of 72 from Bl generation to B5' In each generation quantitative characters, etpecially weight of whole coc06n, qocoon layer and cocoon layer ratio, were corchparatively eamined between the 'two series. The resuits are sumrorized as follows : i) No difference in The physiolotical effects on increase and tlecrease in the weight of whole co-coon, cocoon layer, cdnsequently cocoon layer ratio also, has been found between the strains. 2) Concerning with the degrees of vigor and growth in silkworm stage and propagation o.f moth, no dissinailaritis has appeared between them. 3) For the resistance to flacherie which was unexpectedly and fcrtunately observed in early autumn rearing of B silkworms, both strains showed almost inert as well as the original race 72. 4) All of the results obtained at present proyed that there exists no racial difference wiヴh the action of W-chronosome between the rices OIO and 72. Nei,ther the physiological condition of individual form nor the state of egg-plasnla in which the worm has to develope in embryonal stage, are atte-cted in different way by the replacement W-chromosome of a race with another. And the facts are not unrea*~onable and incomprehnsile matters in accordance with che geneticai conception of sp called inert chrom;osome as W. 5) Nevertheless the uthors are inclined to remain a question,if the transportion of nucleus will be carried out by that of OIO race instead of 72, the result may be possibly turn to another one.
1951-11-30

家蚕の性染色体に関する育種遺伝学的研究 : I.W染色体の品種的差異に就いての検討(第1報)

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