Gene activities in the Malphigian tubules ofDrosophila hydei at different developmental stages
✍ Scribed by Berendes, H. D.
- Publisher
- John Wiley and Sons
- Year
- 1966
- Tongue
- English
- Weight
- 616 KB
- Volume
- 162
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
A detailed analysis of the puffing patterns of Malphigian tubules, stomach and salivary glands of Drosophila hydei revealed that from a total of 110 easily recognizable puffs 76 (69% ) are present i n all tissues at one time or another during mid and late third instar. A small number of puffs showed tissue specific activity. Three such puffs were restricted to the Malphigian tubules, four to the stomach and seven to the salivary glands. A number of puffs was found to be absent in only one of the investigated tissues during the whole of the period. A comparison of the puffs specific for a definite developmental stage revealed that from the 22 puffs in the salivary glands which were specific for the period of puparium formation, only six showed an identical reaction in all tissues. In the late third instar stage three puffs were observed to hecome active earlier i n the stomach than i n the salivary glands, whereas n o activity of these puffs was found in the Malphigian tubules. A possible relation of these puffs to the process of histolysis is discussed.
A comparison of the puffing patterns of Malphigian tubules in larvae and i n adults showed that 12 puffs which were observed in the larvae were absent in the adults. No specjfic puffs occurred in the adult Malphigian tubules.
A detailed comparison of the banding patterns of homologous giant chromosomes from different tissues of the same individual showed no evidence for specific differences (Berger, '41 : Slyzinsky, '50; Beermann, '52). However, distinct structural variations are present in the chroniosomes of different tissues. These structural differences known as bulbs, puffs and Balbiani rings, can be present in one of the tissues, but absent in the others (Becrmann, '52). It is now well known that these structures represent loci with a high synthetic activity, producing RNA (Pelling, '64), or DNA (Pavan, '63). Differences in the chromosomal patterns of active loci might reflect functional differences between individual cells or tissues.