XY1Y2 chromosome system in Salinomys delicatus (Rodentia, Cricetidae)

LANZONE CECILIA; RODRIGUEZ, DANIELA; CUELLO, PABLO; ALBANESE MARÍA SOLEDAD; OJEDA AGUSTINA; CHILLO, VERÓNICA; MARTÍ, DARDO A.

GENETICA

SPRINGER

Lugar: Berlin; Año: 2011 vol. 139 p. 1143 - 1147

0016-6707

Salinomys delicatus is considered a rare species due to its restricted and patchy distribution, poor records and low abundances. It is also the phyllotine with the lowest known diploid chromosome number (2n = 18), however its sex chromosome system has never been described. Here, we studied the chromosomes of six females and three males with bands G, C, DAPI/CMA3 and meiosis. In males, the chromosome number was 2n = 19, with one large metacentric X-chromosome and two med- ium-sized acrocentrics absent in females. The karyotype of females was the same as previously described (2n = 18, FN = 32), with X-chromosomes being metacentric and the largest elements of the complement. In males, the two acrocentrics and the large metacentric form a trivalent in meiotic prophase. This indicates that S. delicatus has XY1Y2 sex chromosomes, which is confirmed by G and DAPI bands. Constitutive heterochromatin (CH) is restricted to small pericentromeric blocks in all chromo- somes. The X-chromosome shows the largest block of centromeric CH, which could favor the establishment of this X-autosome translocation. This sex chromosome sys- tem is rare in mammals and, compared with other phyllo- tine rodents, S. delicatus seems to have undergone a major chromosome restructuring during its karyotypic evolution.