Cytogenetic characterization of sexual chromosomes in the Y-short Anastrepha fraterculus strain

GIARDINI, M.CECILIA; MILLA, F; NIEVES, MARIELA; CLADERA, J.; LANZAVECCHIA, S

Congreso; 21st International Chromosome Conference; 2016

The South American fruit fly, Anastrepha fraterculus (Diptera: Tephritidae) has a XX/XY sex determination system. Information about tephritid species reported the presence of genes encoding male determining factors linked to the Y chromosome, although, no information is available for the species we study. Cytological analysis performed in the A. fraterculus strain maintained in our laboratory enabled the identification of two of the six reported morphological variants of Y chromosomes (Y5 and Y6). A. fraterculus strain carrying Y5 (shorter and more frequently found) were purified and analyzed. We performed the characterization of the sexual heterochromatin by DAPI/CMA and C-bands, and compared our results to the A. fraterculus reference karyotype (which includes a short and sub metacentric Y chromosome with its constitutive heterochromatin distributed in almost the entire chromosome and has AT and GC rich regions). The Y-short A. fraterculus population retains the same heterochromatin distribution of the original population, as was expected. The constitutive heterochromatin extends throughout almost the entire Y chromosome showing AT and GC-rich regions. Furthermore, we identified an AT-rich heterochromatin in both termini of the X chromosome. Further analysis by FISH co-localized the ribosomal genes in the constitutive heterochromatin of the Y chromosome, whereas, the ribosomal genes cluster on the X chromosome is localized at the terminal position in the long arm. This cytological characterization provides new insight to continue exploring A. fraterculus genetics towards the identification of male determining genes in this pest species and the selection of suitable strains for the development of environmental-friendly control strategies.