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Title: Variation in ribosomal and satellite DNAs in the genus Dermestes
Author: MacLean, R.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1981
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The six members of the genus Dermestes investigated here encompass a remarkably wide range of C-values. In this study whole DNAs from each species were extensively characterised. There was no correlation of rRNA gene number with DNA content or taxonomy. Differences were detected between male and female DNAs presumably due to nucleolar organising regions being situated on the sex chromosomes. Competition experiments demonstrated that rRNA sequences were well conserved in the genus. In preparative CsCl gradients the rDNAs banded at greater densities than bulk DNAs. Analyses of first derivative plots of thermal denaturation data confirmed the extremely high content of satellite DNA in the genus. Much of the variation in DNA content reflects variation in the amount of satellite DNA. The long range structures of the satellites were investigated by restriction endonuclease analyses of whole DNAs. For most species-enzyme combinations several bands were detected. No male-specific fragments were found. Only for D. maculatus and D. frischii DNAs did the band patterns demonstrate the presence of related sequences. Finally components were purified from D. m. maculatus DNA. Satellite II melted sharply, reassociated very rapidly and resisted cleavage by restriction endonucleases: satellite II must have a very simple sequence. Satellite I also melted sharply and reassociated rapidly. Restriction revealed tandemly arranged repeats of 190bp with typical Type A and B patterns. Though certain restriction endonuclease sites may be distributed at 190bp intervals, subrepeats may exist within these long range units in view of the very low complexity determined by reassociation. Two novel observations were made: (i) A minor second buoyant density component was detected in the rDNA of D friscbii; (ii) The major satellites of D. maculatus and D. frischii were found to have similarly arranged restriction endonuclease recognition sites despite the basic repeats differing slightly in length and despite there being an 11% discrepancy in base composition.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available