GENERAL-CHARACTERISTICS OF THE POLYTENE CHROMOSOMES FROM OVARIAN PSEUDONURSE CELLS OF THE DROSOPHILA-MELANOGASTER OTU(11) AND FS(2)B MUTANTS

Polytene chromosomes of good cytological quality from pseudonurse cell s (PNCs) of fs(2)B and otu(11) mutants were obtained, photomaps for ot u(11) mutants were constructed and the general characteristics of poly tene chromosomes from salivary glands (sos) and PNCs were compared. Th ree conditions were found to improve the cytological quality of PNC ch romosomes: temperature below 18 degrees C, a protein-rich medium and p resence of the Y-chromosome. Detailed comparison of the chromosome ban ding pattern from Sos and PNCs has shown only minor differences betwee n them. The frequency of asynapsis appeared to be 10 times higher for PNC chromosomes. Despite previous reports, features such as breaks and ectopic contacts turned out to be also typical for PNC chromosomes, b ut with remarkably lower frequencies.