Structural heterogeneity and genomic distribution of Drosophila melanogaster LTR-retrotransposons.
ABSTRACT Structural heterogeneity of five long terminal repeat (LTR) retrotransposon families (297, mdg 1, 412, copia, and 1731) was investigated in Drosophila melanogaster. The genomic distribution of canonical and rearranged elements was studied by comparing hybridization patterns of Southern blots on salivary glands from adult females and males with in situ hybridization on polytene chromosomes. The proportion and genomic distribution of noncanonical copies is distinctive to each family and presents constant features in the four different D. melanogaster strains studied. Most elements of families 297 and mdg 1 were noncanonical and presented large interstock and intrastock polymorphism. Noncanonical elements of these two families were mostly located in euchromatin, although not restricted to it. The elements of families 412 and copia were better conserved. The proportion of noncanonical elements was lower. The 1731 family is mainly composed of noncanonical, beta-heterochromatic elements that are highly conserved among stocks. The relation of structural polymorphism to phylogeny, transpositional activity and the role of natural selection in the maintenance of transposable elements are discussed.
- SourceAvailable from: Ana Domínguez[show abstract] [hide abstract]
ABSTRACT: The intragenomic distribution of five retrotransposon families (297, 1731, copia, mdg1 and roo) in the species of the melanogaster complex was studied by comparing results of the Southern blotting technique in males and females with those of in situ hybridization. The degree of structural polymorphism of each family in the different species was also investigated by restriction enzyme analysis. It was found that genomic distribution is a trait that depends on the family and species. The distribution of roo is mainly euchromatic in the four species and 1731 is heterochromatic, but the distribution of families 297, copia and mdg1 is markedly different in the melanogaster and simulans clades. These families were mainly euchromatic in D. melanogaster but heterochromatic in its sibling species. In the simulans clade most copia and mdg1 elements are located on chromosome Y. Differences in genomic distribution are unrelated with structural conservation. The relation of intragenomic distribution to phylogeny, transpositional activity and the role of the host genome are discussed.Genetica 12/2009; 138(6):579-86. · 1.68 Impact Factor
- Doklady Biochemistry and Biophysics 05/2012; 444:171-4. · 0.32 Impact Factor
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ABSTRACT: The Y loops of Drosophila spermatocytes are formed by the expression of huge individual transcription units on the Y chromosome and their large size provides a unique system for the investigation of the organisation of transcription in intact nuclei. By labelling ribonucleo-protein (RNP) components, the loop chromatin and nascent transcripts in Y loop C, we reveal a highly structured organisation of RNP domains associated with nascent transcripts. We distinguish two types of RNP domain, a proximal domain that runs alongside the chromatin of loop C and a distal RNP domain that wraps around the proximal domain and the loop chromatin. The proximal domain is marked by the Pasilla protein, and separate distal subdomains are marked by the S5 antigen and Boule. We discuss the implications of this highly structured co-transcriptional architecture for the organisation of the process of transcription.Chromosoma 05/2011; 120(4):399-407. · 3.34 Impact Factor