Sharma, AtashiKinney, Nicholas A.Timoshevskiy, Vladimir A.Sharakhova, Maria V.Sharakhov, Igor V.2020-03-272020-03-272020-03-19Sharma, A.; Kinney, N.A.; Timoshevskiy, V.A.; Sharakhova, M.V.; Sharakhov, I.V. Structural Variation of the X Chromosome Heterochromatin in the Anopheles gambiae Complex. Genes 2020, 11, 327.http://hdl.handle.net/10919/97497Heterochromatin is identified as a potential factor driving diversification of species. To understand the magnitude of heterochromatin variation within the <i>Anopheles gambiae</i> complex of malaria mosquitoes, we analyzed metaphase chromosomes in <i>An. arabiensis</i>, <i>An. coluzzii</i>, <i>An. gambiae</i>, <i>An. merus</i>, and <i>An. quadriannulatus</i>. Using fluorescence <i>in situ</i> hybridization (FISH) with ribosomal DNA (rDNA), a highly repetitive fraction of DNA, and heterochromatic Bacterial Artificial Chromosome (BAC) clones, we established the correspondence of pericentric heterochromatin between the metaphase and polytene X chromosomes of <i>An. gambiae</i>. We then developed chromosome idiograms and demonstrated that the X chromosomes exhibit qualitative differences in their pattern of heterochromatic bands and position of satellite DNA (satDNA) repeats among the sibling species with postzygotic isolation, <i>An. arabiensis</i>, <i>An. merus</i>, <i>An. quadriannulatus</i>, and <i>An. coluzzii</i> or <i>An. gambiae</i>. The identified differences in the size and structure of the X chromosome heterochromatin point to a possible role of repetitive DNA in speciation of mosquitoes. We found that <i>An. coluzzii</i> and <i>An. gambiae</i>, incipient species with prezygotic isolation, share variations in the relative positions of the satDNA repeats and the proximal heterochromatin band on the X chromosomes. This previously unknown genetic polymorphism in malaria mosquitoes may be caused by a differential amplification of DNA repeats or an inversion in the sex chromosome heterochromatin.application/pdfenCreative Commons Attribution 4.0 InternationalAnophelesheterochromatinmosquitomitotic chromosomesex chromosomesatellite DNAX chromosomeArticle - Refereed2020-03-27https://doi.org/10.3390/genes11030327