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Title: Two-dimensional gel analysis of repetitive nuclear DNA sequences in the genome of Physarum polycephalum. Developmental regulation of the ribosomal gene number. Author: Meyer G, Hildebrandt A. Journal: Eur J Biochem; 1986 Jun 16; 157(3):507-12. PubMed ID: 3013633. Abstract: The composition of repetitive sequences in restriction patterns of nuclear DNA of Physarum polycephalum was determined by high-resolution gel analysis. Three types of repeated DNA fragments in the size range of (0.2-2) X 10(3) base pairs could be identified as discrete spots on the gels and distinguished by their abundance and above-average base composition of either guanine and cytosine (G + C) or adenine and thymidine (A + T). On comparing the DNA composition from exponentially growing plasmodia with that of starved plasmodia, which have become competent to sporulate and have lost 80% of their nuclei, no change was detected among the (A + T)-rich repeat fractions, whereas several of the (G + C)-rich fractions revealed fewer copies in the DNA prepared from starved cells. As shown by hybridization under saturating conditions, the reduction of several (G + C)-rich repeated sequences in the restricted nuclear DNA in sporulation-competent cells can be explained by a 64% elimination of the extrachromosomal nucleolar ribosomal DNA sequences.[Abstract] [Full Text] [Related] [New Search]