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  • 1975-1979  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 167 (1979), S. 271-277 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary D. melanogaster males of $$\overline {{\text{XY}}}$$ bb/O genetic constitution undergoing rDNA magnification were mated singly to XXbb +/O females, yielding $$\overline {{\text{XY}}}$$ bb/O male progeny, and to XNO-w sn bb + fameles, yielding $$\overline {{\text{XY}}}$$ bb/XNO- females. The male and female offspring were scored for the bb + phenotype. Results show that there is a higher percentage of bb + flies in the $$\overline {{\text{XY}}}$$ bb/O male progeny than in $$\overline {{\text{XY}}}$$ bb/XNO- females progeny, in single crosses as well as in the combined data. rRNA/DNA hybridization experiments agree with this observation, by showing that the rDNA content in the progeny of premagnified flies was higher in the sons than in the daughters. These data indicate that the increase of ribosomal RNA genes is not due to a stable event such as an unequal mitotic sister exchange, whereas they do not contrast with the extracopy model.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 145 (1976), S. 255-258 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The purpose of this work was to analyze the difference between males and females with respect to rDNA magnification. To study eventual rDNA variations in females a Ybb chromosome was chosen since it can magnify in males but not show phenomena of rDNA dosage compensation. The authors have observed an increase of rDNA pertaining to the Ybb chromosome in females of $$\widehat{{\text{XX}}}_{_{NO} - } /Ybb$$ genotype with respect to the same Ybb chromosome studied in $$\widehat{{\text{XX}}}bb^ + /Ybb$$ females. This non-inheritable rDNA increase cannot be explained in terms of compensatory increase reported in X/O males nor can it fit in the magnification scheme. The possibility might be entertained that some mechanism is missing in females which cannot complete a magnification cycle. The rDNA increase that we called rDNA magnification in males occurs in the germ line and in the soma, whereas the evidence, here reported, suggest that magnification in females occurs only in the soma.
    Type of Medium: Electronic Resource
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