Abstract
Two stocks of Chironomus tepperi could be isolated. One stock, N(IV)+, contains nucleolus organizers in chromosome I and IV, whereas the other one, N(IV)−, shows only one nucleolus in chromosome I. It is demonstrated by in situ hybridization with radioactive rRNA that the absence of the nucleolus in chromosome IV of stock N(IV)− is not related to an inactivation of the nucleolar DNA, as might have been suggested, but is due to the lack of ribosomal cistrons.
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Eigenbrod, J. Differences in the number of nucleolus organizers in Chironomus tepperi shown by in situ hybridization. Chromosoma 67, 63–66 (1978). https://doi.org/10.1007/BF00285648
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DOI: https://doi.org/10.1007/BF00285648