The retrotransposon family micropia in Drosophila species
During the diplotene of the prophase of meiosis, the oocytes of many animal species contain spectacular chromosome structures called lampbrush loops (reviewed e.g. by 4Callan, 1987; 5Davidson, 1986). Their basic function seems to be the synthesis and maintenance of a large pool of pre-zygotic transcripts. In most Drosophila species it is the Y-chromosome that develops lampbrush loops in primary spermatocytes during the prophase of meiosis. The Y chromosome is only needed during spermatogenesis as males lacking the Y chromosome are completely viable but sterile (Bridges, 1916). Except during meiosis, the Y chromosomes remain condensed, a typical feature of heterochromatin. Corresponding to this is its repetitive sequence organization which has caused problems in establishing the true origin of these sequences from the Y chromosomal lampbrush loops (Vogt & 30Hennig, 1983). These difficulties were overcome by the application of the microcloning technique to dissect and then directly clone sequences from less than 0.1 pg of Y chromosomal lampbrush loop DNA (12Hennig et al., 1983; Hennig et al., 1989). In order to succeed with these experiments lampbrush loop structures of primary spermatocytes from Drosophila hydei, known to contain the most distinctive loops among all Drosophila species, were micro-dissected from partial Y chromosomes carrying only one or two lampbrush loops (Hackstein et al., 1982). ‘Microclones’ recovered from the lampbrush loops ‘Threads’ and ‘Pseudonucleolus’ led to the discovery of the micropia retrotransposon family (15Huijser et al., 1988; 20Lankenau et al., 1988>).
KeywordsTransposable Element Drosophila Species Primer Binding Site Primary Spermatocyte Baltic Amber
Unable to display preview. Download preview PDF.
- Callan, H. G., 1987. Lampbrush Chromosomes as seen in histor ical perspective, pp. 5–26 in Structure and Function o Eukaryotic Chromosomes, edited by W. Hennig, Springer Heidelberg NY.Google Scholar
- Davidson, E. H., 1986. Gene Activity in early development Academic Press, NY.Google Scholar
- Grimaldi, D. A., 1990. A phylogenetic revised classification a genera in the Drosophilidae (Diptera). Bulletin of the Amer kan Museum of natural History, 197, NY.Google Scholar
- Grimaldi, D. A., 1987. Amber fossil Drosophilidae (Dipter; with particular reference to the Hispaniolan taxa. Am. Mi Novitates 2880: 1–23.Google Scholar
- Grimaldi, D. A., 1988. Relicts in the Drosophilidae (Dipter pp. 183-213 in Zoogeography of Carribean insects, edited by J. K. Liebherr. Ithaca, Cornell University Press.Google Scholar
- Hennig, W. sen., 1965. Die Acalyptratae des Baltischen Bernsteins. Stuttg. Beitr. Naturkd. No. 145.Google Scholar
- Huijser, P., 1987. Genomic organization of microdissected Y-chromosomal lampbrush loop DNA sequences of Drosophila hydei. Ph. D. Thesis, University of Nijmegen, The Netherlands.Google Scholar
- Lankenau, D.-H., 1990. Molecular structure and evolution of a retrotransposon family in Drosophila. Ph. D. Thesis, University of Nijmegen, The Netherlands.Google Scholar
- Throckmorton, L. H., 1975. The Phylogeny, Ecology, and Geography of Drosophila, pp. 421–469 in Handbook of Genetics, vol. 3, edited by R. C. King. Plenum Press, NY.Google Scholar
- Wasserman, M., 1982. Evolution of the repleta group in Genetics and Biology of Drosophila, 3b, Ashburner, M., H. L. Carsons and J. N. Thompson, Jr., Eds. Academic Press.Google Scholar
- Winkler-Oswatitsch, R., A. Dress & M. Eigen, 1986. Comparative Sequence Analysis — Exemplified with tRNA and 5S-rRNA. Chemica Scripta 26B: 59–66.Google Scholar