ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract We have examined DNA from polytene salivary glands and diploid brains and imaginal discs of male and female larvae having one or two nucleolus organizers. DNA having an estimated molecular weight of 5×109 or greater was obtained by sucrose gradient sedimentation of gently prepared lysates. Hybridization of the gradient fractions with 3H-ribosomal RNA reveals that 42% of the ribosomal genes are found in DNA of lower molecular weight (approximately 3×108 daltons) in the salivary glands of every genotype examined. In the brains and imaginai discs, by contrast, all of the ribosomal genes are found in the high molecular weight peak except in females with one nucleolus organizer where 42% are found in lower molecular weight DNA, as in the salivary gland. Thus unintegrated genes are not an exclusive feature of polytene tissue, but can occur in diploid tissue as well in at least one genotype.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00292089
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