唾腺染色体の構造についてII

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This paper deals with the structure of the salivary gland chromosomes by the study with various pH solutions and by observations of the developmental process during the early larval stages. The materials employed were Drosophila virilis, Spnianitoma akamusi and Simulium salopiedse. The buffer solutions were prepered by Sorensen's and Kolthoff's methods. NaCl was added to each pH solution and the concentration of NaCl was made 1/5 Normal. Salivary glands were treated with these buffer solutions for five minutes in each experiment. When the salivary glands of these species were treated with acid solutions, the chromosomes in the glands showed the following appearances: in the chromosomes of Spanitoma a criss-crossed appearance as reported by Metz (1941), in Simulium a structure of longitudial threads connecting the bands as described by Painter (1941) and in Drosophila an appearance nearly the same as non-treated raw materials. These appearances of the chromosomes corresponded with those in the case of treatment with aceto-carmine. In the treatment with the pH 6-8 solutions remarkable vacuolations were observed in the chromosomes of each species. In the solutions of pH 9-10 the chromosomes of both Drosophila and Spanitoma were observed to resemble those of Metz's figures. With the same solutions the chromosomes of Simulium failed to show the Metz's figures, but appeared as the longitudinal threads running along the long axis of the chromosome. In the pH 11-12 solutions, however, the chromosomes of all species showed above mentioned longitudinal threads. These threads morphologically resembled those observed in the chromosomes treated with the pH 3-5 solutions (Fig. 1 and 2). The results obtained in the treatments with acid solutions show that the salivary gland chromosomes have the species-specific reactions to the aceto-carmine fixative, since in these cases nucleic acids are fixed in situ, at the bands or granules. The shift from the Metz's figure into the longitudinal threads observed in the alkaline treatment is assumed to depend on the relaxation of the tangle or spiral of the homologous chromosomes. It is assumed from this result that a prolongation of each homologue occurs and thus the longitudinal threads become paralell through the chromosome. Based on these data it seems reasonable to state that the longitudinal threads observed in the alkaline solutions correspond with those fixed by aceto-carmine or in the acid solutions. Recently Kaufmann (1952) reported that the electric-micro-scopic figures of the salivary chromosomes show obviously the longitudinal threads connecting the bands. From these data one might conclude that the longitudinal threads observed in the aceto-carmine fixation and also in the raw materials are the fundamental structure of the salivary chromosomes. Furthermore we investigated the tangle of the maternal and paternal chromosomes in the nuclei of the salivary glands of Chironomus dorsalis (Fig. 3 and 4), with raw materials and fixed materials. In the case of the youngest larva so far obtained, the homologous chromosomes tangled each other compactly. This tangle become laxative with the increase in age of the larvae. The bands could be seen in the chromosomes of the youngest larva. It seems, therefore, that the bands appear already at the hatching stage of a larva.
社団法人日本動物学会の論文
1955-02-15

唾腺染色体の構造についてII

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