Chromosomal variability of sex chromosomes and NOR's in Trichomys apereoides (Rodentia, Echimyidae).
G-banding, C-banding, and silver staining techniques were used to analyze the chromosomes of Trichomys apereoides. In a sample of 22 specimens the diploid number was 2n = 30, with several pairs of biarmed chromosomes and a large metacentric (pair 1) with a secondary constriction, or nucleolar organizing region (NOR), in the short arm. One male had a heteromorphic pair 1, with only one NOR-bearing homolog. C-bands showed constitutive heterochromatin in the centromeric region of almost all autosomes. The X has a large block in the proximal region and an interstitial small band in the long arm. The Y is totally heterochromatic. One heteromorphic female with an increased C-band block in one of the X chromosomes was observed. The Y is a small submetacentric; one male showed a metacentric Y, resulting probably from a pericentric inversion. The sexual bivalent and the synaptonemal complexes of all autosomal bivalents were revealed by silver staining in pachytene cells.
D000818:Animals; D002871:Chromosome Banding; D002875:Chromosomes / Q000648:ultrastructure*; D005260:Female; D014644:Genetic Variation; D006570:Heterochromatin / Q000032:analysis; D007621:Karyotyping; D008297:Male; D009115:Muridae / Q000235:genetics*; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D012730:Sex Chromosomes / Q000648:ultrastructure
D006570:Heterochromatin