Structure of rDNA in the mosquito Anopheles gambiae and rDNA sequence variation within and between species of the A. gambiae complex.

The structure of the rDNA repeating unit of Anopheles gambiae (Diptera: Culicidae) was determined by restriction endonuclease mapping and hybridization analyses on four independent clones obtained from a genomic library of a colony (G3) from the Gambia (West Africa). rDNA gene coding sequences are conserved, but much intragenomic and intraspecific (geographic) variation occurs in the intergenic spacer. Hybridization of subclones from spacer and coding sequences to genomic DNA that was isolated from single mosquitoes from laboratory colonies of four other A. gambiae complex species reveals conservation of coding sequences but concerted evolution in the intergenic spacers.