Inter- and intraspecific heterochromatin variation detected by restriction endonuclease digestion in two sibling species of the Anopheles maculipennis complex


Inter- and intraspecific heterochromatin variation detected by restriction endonuclease digestion in two sibling species of the Anopheles maculipennis complex

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The sibling species Anopheles atroparvus and Anopheles labranchiae are cytogenetically almost indistinguishable. The chromosome complement (2n = 6) consists of two pairs of autosomes and two


heteromorphic sex chromosomes with largely homologous heterochromatic long arms. Treatment of chromosome preparations with the restriction endonucleases, Alu I, Hae III, Mbo I, Hpa II,


revealed species-specific differences of the sex chromosome banding pattern. These differences involved both amount and location of digested heterochromatin. Heterochromatin heterogeneity


and a high level of intraspecific polymorphism, undetected with standard banding techniques, were observed in both species. Quantitative heterochromatin differences between the sex


chromosomes did not inhibit their pairing and chiasmata formation. The endonuclease Msp I, which cleaves the same target sequence as Hpa II, did not digest heterochromatic as well as


euchromatic regions in both species: inhibition of cleavage by methylation of the target sequence or limited access of the enzyme to the target could be involved in this response.


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