Puffing patterns in the salivary gland chromosomes of the melonfly,Dacus cucurbitae |
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Authors: | H. N. B. Gopalan C. M. S. Dass |
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Affiliation: | (1) Centre for Advanced Research in Cell Biology and Endocrinology, Department of Zoology, University of Delhi, Delhi-7, India;(2) Present address: Institut für Genetik, Universität des Saarlandes, 66 Saarbrücken 15, West Germany |
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Abstract: | The puffing pattern changes in the salivary gland chromosomes of the third instar larvae of the melonfly, Dacus cucurbitae are described. Three classes of puffs were noticed over a period of development of 120 hrs. Class (1) are those which are more or less constantly found; class (2) are those which oscillate, i.e. appear and disappear at irregular time intervals; and class (3) are those that are linked to a specific developmental event. Also, 3 peaks of puffing activity have been noticed during the present study; one in the 120 hr old larva, the second in the 168 hr old larva and the third in the 240 hr old larvae. The significance of these 3 classes of puffs and the 3 peaks in puffing activity has been discussed. The puff RNA has a high rate of synthesis and incorporates 3H-cytidine within 30 secs after being offered. There is a high degree of variation in the incorporation of labelled precursors into the different nuclei of the same gland, such a variation is not noticed in the diploid and embryonic cells. |
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