Structural evolution of the Drosophila 5S ribosomal genes

Abstract

We compare the 5S gene structure from nine Drosophila species. New sequence data (5S genes of D. melanogaster, D. mauritiana, D. sechellia, D. yakuba, D. erecta, D. orena, and D. takahashii) and already-published data (5S genes of D. melanogaster, D. simulans, and D. teissieri) are used in these comparisons. We show that four regions within the Drosophila 5S genes display distinct rates of evolution: the coding region (120 bp), the 5'-flanking region (54-55 bp), the 3'-flanking region (21-22 bp), and the internal spacer (149-206 bp). Intra- and interspecific heterogeneity is due mainly to insertions and deletions of 6-17-bp oligomers. These small rearrangements could be generated by fork slippages during replication and could produce rapid sequence divergence in a limited number of steps.

Distribution and molecular composition of heterochromatin in the holocentric chromosomes of the aphid Rhopalosiphum padi (Hemiptera: Aphididae)

“…2), combined with densitometric analyses, allowed us to estimate in more than 400 copies the number of the DraI satellite DNA in the R. padi genome by comparison with the 5S rDNA genes whose amount has been estimated in 100-120 copies per haploid genome in insects (Paques et al 1995).…”

Effects of permissible maximum-contamination levels of VOC mixture in water on total DNA, antioxidant gene expression, and sequences of ribosomal DNA of Drosophila melanogaster

“…The ribosomal DNA is a DNA sequence assembled from the external transcribed spacer (ETS) and the 18S, ITS1, 5.8S, ITS2, and 28S units. Coding in the 18S and 28S regions are known to be conserved (Paques et al 1995), but the ITS regions are variable because of bearing insertions, deletions, and point-mutation sources from environmental signals (Sumida et al 2004). Currently, hundreds of genes are known to be responsible for environmental stress defence mechanisms in Eukaryotic genomic DNA, and many have assigned functions in the stress response (Loar et al 2004).…”

S6 Kinase is essential for MYC-dependent rDNA transcription in Drosophila

“…[ 32 P]-labelled riboprobes were generated by PCR from genomic DNA corresponding to a 170 nucleotide fragment (region +92 to +266) of the 5′ external transcribed spacer (5′ETS) of the Drosophila 37S rRNA precursor [73,74]. The fragment was cloned into pGEM3Z vector and linearised with Hind III.…”