Replication in Drosophila chromosomes XIII. Comparison of late replicating sites in two polytene cell types in D. hydei

Abstract

We have compared the temporal order of completion of replication of specific sites of X and 2nd chromosomes in two polytene cell types of D. hydei by examining the patterns of autoradiographic labelling in ³H-thymidine pulse (10 min) labelled salivary glands and gastric ceaca of mid 3rd instar larvae. Present results are in agreement with our earlier finding in D. nasuta (Lakhotia & Tiwari, 1984, Chromosoma, 89: 212-217 that in spites of a general similarity in the cytological identity of independently replicating sites in the two polytene cell types, their temporal programme of replication varies in different tissues. This may be related to differential gene activity patterns and polytene organization in the different cell types.