Increased number of nucleoli in the salivary gland cells of Drosophila melanogaster under conditions of rDNA dose compensation

Semionov, E. P.; Kirov, Nikolai Kh.

doi:10.1007/bf00386787

Cited by 8 publications

(11 citation statements)

References 36 publications

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“…2a-d) was, in a general way, similar to the pattern described earlier for D. melanogaster (Ananiev et al, 1981;Semionov & Kirov, 1986). In particular, the appearance of large additional nucleoli correlates with the reduction of the 'basal' nucleoli (Semionov et al, 1978; see also Fig.…”

Section: Discussionsupporting

confidence: 65%

“…Similar differences of the nucleolar organization of Drosophila species were observed earlier for the repleta group (Hennig et al, 1982). As might have been expected, in two other hybridsinsertion sequences only within the NOs and the mesi (D. melanogaster X D. simulans) and mema nucleoli (Semionov et al, 1986). In D. simulans (D. melanogaster X D. mauritiana) -we have polytene nuclei, two additional loci at 75B and dectected type I elements within the chromocenter 80BC of chromosome 3 were observed for this and the 102C region of chromosome 4, i.e.…”

Section: Distribution Of Type I and Type Ii Insertions Along The Polysupporting

confidence: 60%

“…Outside the NO, polytene nuclei of all D. melanogaster stocks tested up to this moment (and Canton S, as well) have revealed type I insertion sequences at the chromocentre and at the 102C region of chromosome 4 (Kidd & Glover, 1980;Peacock et al, 198 1;Hilliker & Appels, 1982;Semionov & Kirov, 1986). The same was true for Canton-S female larvae after hybridization of the plasmid pC2 (data not shown).…”

Section: Distribution Of Type I and Type Ii Insertions Along The Polysupporting

confidence: 58%

“…2 a-b). Possible origins of type I insertioncontaining chromosomal sites, to which rDNA of the nucleoli may be connected, have been discussed earlier (Semionov & Kirov, 1986). Since the location of these sites of the incomplete type of labeling (ITL) within polytene chromosomes varies, a criterion which allows us to distinguish them from the unspecific background should exist.…”

Section: Discussionmentioning

confidence: 99%

“…Besides the nucleoli associated with the NO, additional nucleoli attached to various chromosoma1 sites have been detected in these nuclei. It has been shown that the rDNA of the additional nucleoli is actively transcribed and replicated (Ananiev et al,198 l), and contains all kinds of the repeated units without insertions, type I+ and type II+ as in the 'basal' nucleolus (Semionov & Kirov, 1986). The frequency of formation of such nucleoli increases proportionally to the level of polyteny.…”

Section: Introductionmentioning

confidence: 93%

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Localization of ribosomal DNA insertion elements in polytene chromosomes of Drosophila simulans, Drosophila mauritiana and their interspecific hybrids

Mecheva

Semionov

1992

Genetica

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The locations of the ribosomal DNA (rDNA) insertion elements type I and type II along the polytene chromosomes of three Drosophila species of the melanogaster subgroup--D. simulans, D. mauritiana and D. melanogaster--have been compared. In situ hybridization has shown that the intragenomic distribution of type I as well as of type II insertions is different for these related species. In particular, we have revealed rDNA-free autosomal sites, containing type II element sequences within the D. simulans and D. mauritiana chromosomes. This finding confirms the ability of this type of insertion to transpose, as was demonstrated earlier for Bombyx mori. The appearance of the rDNA not associated with the nucleolar organizers, evident by additional nucleoli, occurred with species-specific frequency. At the same time, for all three species the pattern of such changes (an attachment of the nucleoli to varying sites of the chromosomes and the presence of ectopic contacts between them, a composition of the rDNA repeats in the nucleolar material not integrated at the nucleolar organizer) was similar. The number of additional nucleoli in the hybrid polytene nuclei corresponded to the value of the parental species exhibiting nucleolar replicative dominance.

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Section: Discussionsupporting

confidence: 65%

Section: Distribution Of Type I and Type Ii Insertions Along The Polysupporting

confidence: 60%