[The comparative analysis of the mutational variability and instability of the thi, Bd strains induced by exogenous viral DNA in Drosophila melanogaster]. / Sravnitel'nyi analiz mutatsionnoi izmenchivosti i nestabil'nosti linii thi, Bd, indutsirovannykh ékzogennoi virusnoi DNK, u Drosophila melanogastrer.

Frequency of reversions to wild type varies for thi and its derivatives from 10(-2) to 10(-5). A broad spectrum of mutations arises in thi alleles and thi+ revertants. Among them there are r, w, Bd and new mutations causing scalloped wings with thickened veins in all the autosomes. In the offspring of a Cy/thi 1 male a fly is found carrying a thi 1 allele in the Cy chromosome; this is not caused by crossing-over, but probably by a transposition. Mutations in the thi, Bd strains and their derivatives are supposed to be caused by small insertion. The nature of these insertions are under discussion.

[Mutation variability and instability in the Drosophila melanogaster thickened 2 strain and its derivatives]. / Mutatsionnaia izmenchivost' i nestabil'nost' v linii thickened 2 Drosophila melanogaster i ee proizvodnykh.

Mutations in Drosophila melanogaster thi2 strain obtained using exogenous viral DNA, and in the thi2 derivatives, have been studied. Revertants to the wild type arose with high frequency (1-2.10(-2)) in both 83f-7 (1-2.6-5.3) and the initial thi2 (2-71.4) strains. New mutations of chromosome 2, non-allelic to the thi2, though with thi2-like phenotypic effects, and some lethal alleles of these mutations have been found in the progeny of the revertants from the thi2 to the wild type in 83f-7 strain. Cytological analysis has failed to disclose large chromosome aberrations of salivary gland chromosomes carrying the mutations r83f-3 (1-54.5), 83f-7, 83f-21 (3-67.1) originated from the thi2 strain. The data are consistent with possibility that mutations from the thi2 strain and its derivatives were formed by means of a small insertion sequence.

Cytogenetic analysis of the 2B3-4--2B11 region of the X-chromosome of Drosophila melanogaster. I. Cytology of the region and mutant complementation groups.

There are, at least, 11 distinct single bands and one real doublet in the region 2B1-2--2C1-2 of the X-chromosome of Drosophila melanogaster. This figure coincides with that in Bridges' revised map with most of the "doublet" bands being artifacts. Three puffs appear in the region. The early ecdysone-specific puff 2B5-6, small at PS(puffing stage) 1, increases sharply at PS 2. The late ecdysone-specific puff 2C1-2 appears at PS 4--5. At PS 9--10, when 2B5-6 disappears completely and 2C1-2 decreases, a third puff at 2B11 appears. None of these puffs is active at PS 11. Morphological analysis of puff appearance and autoradiographic study of 3H-uridine incorporation into chromosomes carrying rearrangements within the 2B region suggest that the early ecdysone-specific puff derives from bands 2B5 and may be 2B6, while the neighbouring bands 2B1-4, and 2B7-10 do not show appreciable transcription at the investigated stages. There are 42 mutations affecting viability in the region where the 2B5-6 puff is located. The mutations belong to 6 complementation groups; two of the groups dor and swi, are independent while the rest are overlapped by several lethal mutations (overlapping complex.) Mutants of the different groups have series of similar characteristics: temperature sensitivity, dose sensitivity, larva-pupal lethality and similar morphological abnormalities. It can be assumed that there is a functionally linked cluster of genes within the region 2B. Complementation groups br, rbp, l(1)pp-1, l(1)pp-2 (overlapping complex) have been located by rearrangements in very narrow cytological limit 2B3-4--2B5 that is in the area of developing puff. Two other loci dor and swi are situated some to the right of 2B5.