scholarly journals EVIDENCE FOR A COMPLEX CLASS OF NONADENYLATED mRNA IN DROSOPHILA

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 673-691
Author(s):  
J Lynn Zimmerman ◽  
David L Fouts ◽  
Jerry E Manning
Keyword(s):  
Dna Sequences ◽  
Polytene Chromosomes ◽  
Single Copy ◽  
Drosophila Genome ◽  
Coding Sequences ◽  
Sequence Complexity ◽  
Relative Contribution ◽  
Copy Dna ◽  
Average Size ◽  
Single Copy Dna

ABSTRACT The amount, by mass, of poly(A+) mRNA present in the polyribosomes of third-instar larvae of Drosophila melanogaster, and the relative contribution of the poly(A+) mRNA to the sequence complexity of total polysomal RNA, has been determined, Selective removal of poly(A+) mRNA from total polysoma1 RNA by use of either oligo-dT-cellulose, or poly (U)-sepharose affinity chromatography, revealed that only 0.15% of the mass of the polysomal RNA was present as poly(A+) mRNA. The present study shows that this RNA hybridized at saturation with 3.3% of the single-copy DNA in the Drosophila genome. After correction for asymmetric transcription and reactability of the DNA, 7.4% of the single-copy DNA in the Drosophila genome is represented in larval poly(A+) mRNA. This corresponds to 6.73 × 1O6 nucleotides of mRNA coding sequences, or approximately 5,384 diverse RNA sequences of average size 1,250 nucleotides. However, total polysomal RNA hybridizes at saturation to 10.9% of the single-copy DNA sequences. After correcting this value for asymmetric transcripti0n and tracer DNA reactability, 24% of the single-copy DNA in Drosophila is represented in total polysomal RNA. This corresponds to 2.18 × 107 nucleotides of RNA coding sequences or 17,440 diverse RNA molecules of size 1,250 nucleotides. This value is 3.2 times greater than that observed for poly(A+) mRNA, and indicates that ≃69% of the polysomal RNA sequence complexity is contributed by n0nadenylated RNA. Furthermore, if the number of different structural genes represented in total polysomal RNA is ≃1.7 × 104, then the number of genes expressed in thirdinstar larvae exceeds the number of chromomeres in Drosophila by about a factor of three. This numerology indicates that the number of chromomeres observed in polytene chromosomes does not reflect the number of structural gene sequences in the Drosophila genome.

Identifying a single-copy DNA sequence associated with the expression of a heterochromatic gene, the light locus of Drosophila melanogaster

Genome ◽  
1990 ◽  
Vol 33 (3) ◽  
pp. 405-415 ◽  
Author(s):  
Robert H. Devlin ◽  
David G. Holm ◽  
Karen R. Morin ◽  
Barry M. Honda
Keyword(s):  
Drosophila Melanogaster ◽  
In Situ Hybridization ◽  
Dna Sequences ◽  
Polytene Chromosomes ◽  
Single Copy ◽  
Molecular Organization ◽  
Copy Dna ◽  
Single Copy Dna ◽  
P Transposon

Although little is known about the molecular organization of most genes within heterochromatin, the unusual properties of these chromosomal regions suggest that genes therein may be organized and expressed very differently from those in euchromatin. We report here the cloning, by P transposon tagging, of sequences associated with the expression of the light locus, an essential gene found in the heterochromatin of chromosome 2 of Drosophila melanogaster. We conclude that this DNA is either a segment of the light locus, or a closely linked, heterochromatic sequence affecting its expression. While other functional DNA sequences previously described in heterochromatin have been repetitive, light gene function may be associated, at least in part, with single-copy DNA. This conclusion is based upon analysis of DNA from mutations and reversions induced by P transposable elements. The cloned region is unusual in that this single-copy DNA is embedded within middle-repetitive sequences. The in situ hybridization experiments also show that, unlike most other sequences in heterochromatin, this light-associated DNA evidently replicates in polytene chromosomes, but its diffuse hybridization signal may suggest an unusual chromosomal organization.Key words: polytene chromosomes, P transposon, in situ hybridization, middle-repetitive DNA.

scholarly journals COMPLEXITY OF RNA IN EGGS OF DROSOPHILA MELANOGASTER AND MUSCA DOMESTICA

Genetics ◽  
1980 ◽  
Vol 95 (1) ◽  
pp. 81-94
Author(s):  
Barbara R Hough-Evans ◽  
Marcelo Jacobs-Lorena ◽  
Michael R Cummings ◽  
Roy J Britten ◽  
Eric H Davidson
Keyword(s):  
Drosophila Melanogaster ◽  
Musca Domestica ◽  
Single Copy ◽  
Drosophila Genome ◽  
Sequence Complexity ◽  
Single Copy Sequence ◽  
Short Period ◽  
Copy Sequence ◽  
Copy Dna ◽  
Single Copy Dna

ABSTRACT Comparative measurements are presented of the sequence complexity of the RNA stored in the eggs of two dipteran flies, Musca domestica and Drosophila melanogaster. The genome of Musca is about five times the size of the Drosophila genome and contains about 3.6 times as much single-copy sequence. As shown earlier, the interspersion of repetitive and single-copy sequence is of the short-period form in Musca, and is of the long-period form in Drosophila. The egg RNA complexities were determined by hybridization of excess RNA with radioactively labeled single-copy DNA. Complexity is expressed as the length (in nucleotides) of diverse single-copy sequence represented in the RNA. The complexity of the RNA of the Musca egg is about 2.4 x 107 nucleotides, and that of the Drosophila egg is about 1.2 x 107 nucleotides. The RNA of the Musca egg is similar to or very slightly lower in complexity than that of other egg RNAs, e.g., those of Xenopus and sea urchin. Compared to all previously measured egg RNAs, Drosophila egg RNA is low in sequence complexity.

Electron microscopy of Achlya deoxyribonucleic acid sequence organization

1981 ◽  
Vol 1 (2) ◽  
pp. 136-143
Author(s):  
M Pellegrini ◽  
W E Timberlake ◽  
R B Goldberg
Keyword(s):  
Dna Sequences ◽  
Deoxyribonucleic Acid ◽  
Microscopic Analysis ◽  
Single Copy ◽  
Electron Microscopic ◽  
Sequence Organization ◽  
Double Stranded Dna ◽  
Copy Dna ◽  
Gene 32 ◽  
Single Copy Dna

Electron microscopic analysis of reassociated deoxyribonucleic acid (DNA) from the aquatic fungus Achlya bisexualis revealed details of the sequence arrangement of the inverted repeats and both the highly and moderately repetitive sequence clusters. We used the gene 32 protein-ethidium bromide technique for visualizing the DNA molecules, a procedure which provides excellent contrast between single- and double-stranded DNA regions. Long (greater than 6-kilobase) DNA fragments were isolated after reannealing to two different repetitive C0t values, and the renatured structures were then visualized in an electron microscope. Our results showed that the inverted repeat sequences were short (0.5 kilobase, number-average) and separated by nonhomologous DNA of various lengths. These pairs of sequences were not clustered within the genome. Both highly repetitive and moderately repetitive DNA sequences were organized as tandem arrays of precisely paired, regularly repeating units. No permuted clusters of repeating sequences were observed, nor was there evidence of interspersion of repetitive with single-copy DNA sequences in the Achlya genome.

scholarly journals Genomic distribution of repeated and single copy DNA sequences inPenicillium funiculosum

1987 ◽  
Vol 40 (2-3) ◽  
pp. 315-319 ◽  
Author(s):  
N.A. Sahasrabudhe ◽  
M.N. Sainani ◽  
V.S. Gupta ◽  
P.K. Ranjekar
Keyword(s):  
Dna Sequences ◽  
Single Copy ◽  
Genomic Distribution ◽  
Copy Dna ◽  
Single Copy Dna

scholarly journals Molecular and chromosomal characterization of repeated and single-copy DNA sequences in the genome of Dasypyrum villosum

Hereditas ◽  
2008 ◽  
Vol 116 ◽  
pp. 55-65 ◽  
Author(s):  
C. DE PACE ◽  
V. DELRE ◽  
G. T. SCARASCIA MUGNOZZA ◽  
C. O. QUALSET ◽  
R. CREMONINI ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Single Copy ◽  
Dasypyrum Villosum ◽  
Copy Dna ◽  
Single Copy Dna
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