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Satellite DNA of the red flour beetle Tribolium castaneum - comparative study of satellites from the genus Tribolium

A highly abundant satellite DNA comprising 17% of the Tribolium castaneum (Insecta, Coleoptera) genome was cloned and sequenced. The satellite monomer is 360 bp long, has a high A+T content of 73% and lacks significant internal substructures. Comparison of T. castaneum satellite with those from three different congeneric species reveals the highest sequence ssimilarity of 47.1% with the satellite from the sibling species T. freemani. The phylogenetic relationships among Tribolium species deduced from satellite sequences agree with those based on karyolgical, chemotaxonomic and hybridization data. This indicates a parallel in the divergence of satellites and some genetic and cytogenetic characters. Despite a low mutual sequence similarity, which makes them species - specific, Tribolium satellites have a common structural characteristic: a block of about 95% A+T content, 20 to 42 bp long, flanked at one side by an inverted repeat which can potentially form a thermodinamically stable dyad structure. Since similar structural features are found in centromeric DNA of Saccharomyces cerevisiae and Chironomus pallidivittatus, their possible importance in centromeric function may be inferred.

satellite DNA ; tribolium castaneum ; evolution ; speciation ; phylogeny ; heterochromati n ; centromere

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