Amplification of tropharium rDNA in the telotrophic ovariole of the bug,<i>Dysdercus intermedins</i>

Dittmann, Frank; Steinbrück, Günther; Münz, Axel

doi:10.1080/07924259.1990.9672082

Cited by 4 publications

(2 citation statements)

References 26 publications

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“…The variation of rDNA signals evidently does not affect the mean DNA content of the nuclei. This is consistent with the finding that the ribosomal genes of various insect species amount to only about 1% or" the total genome (park and Fallon 1990 (Dittmann et al 1990). In this case, a 14fold rDNA amplification takes place in the diploid stem cells, and the amplified rDNA is subsequently multiplied in step with the genome by seven endomitotic replications up to the first gonocycle.…”

Section: Discussionsupporting

confidence: 91%

“…This could be a consequence of rDNA underreplication during endomitotic polyploidization, as it occurs in many dipteran tissues (reviewed in Spradling and Orr-Weaver 1987). Underreplication of rDNA has also been suggested to account for the observed reduction of rDNA gene copy number in polyploid female fat body cells of Locusta migratoria (Oishi et al 1985) and ovarian follicle cells of Dysdercus intermedius (Dittmann et. al.…”

Section: Discussionmentioning

confidence: 99%

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Disproportionate numbers of rDNA loci in diploid and polyploid testis nuclei of gerris najas detected by fluorescence in situ hybridization

Becker

Nagl

1994

Cell Biology International

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The replication state of rDNA in testes nuclei undergoing polyploidization by classical‐type endomitosis was investigated in Gerris najas (Heteroptera) by means of fluorescence in situ hybridization. The number of just one rDNA locus per haploid genome was determined by in situ hybridization on meiotic nuclei. Additionally, DNA measurements of spermatids and testes nuclei were performed. Although regular duplication levels of nuclear DNA were found within the limits of the accuracy of the method, these did evidently not apply to the ribosomal genes. The comparison of the number of rDNA signals with the DNA content of 106 testis nuclei revealed drastic variations of the number of rDNA loci between individual nuclei with similar DNA content. Polyploid nuclei of the testis epithelium showed too low numbers of rDNA loci in relation to those expected from the levels of ploidy, while cyst cell nuclei displayed increased numbers of rDNA loci. The results indicate that the ribosomal genes are either underreplicated, or in part eliminated, during the endomitotic cycles of epithelium cell nuclei, but amplified in the cyst cell nuclei, probably already at their diploid stage.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%