title: Revised karyotype of Alouatta caraya (Primates: Platyrrhini) based on synaptonemal complex and banding analyses.
abstract: Most primates studied have the usual XX/XY sex-chromosome system. However, exceptions to this rule among howler monkeys have been suggested by several authors. Recently a quadrivalent was discovered in male meiosis of Alouatta caraya and it was established that this species has an X1X2Y1Y2 sex chromosome system. On that basis, a cytogenetic analysis of 25 males of this species is described, showing the corrected karyotype of this species. Each chromosome involved in the particular sex-chromosome system of this species is identified on the basis of mitotic chromosome measurements, G and C-banding patterns as well as on the relative measurements of synaptonemal complexes. It is now established that A. caraya has a karyotype with 2n = 52 in both sexes, and that the male one shows a single autosome #7 (X2) besides the X (X1) and the two products of the reciprocal translocation between the second autosome #7 and the Y chromosome (Y1 and Y2), while females show a homomorphic pair #7 (X2) and a pair of X1. The evolutionary implications of the exceptional primate species having composite sex-chromosome systems are discussed.
authors.affiliation: Depto. de Biología, Facultad de Cs. Exactas y Naturales (FCEyN), Universidad de Bs.As., (UBA), Argentina.
authors.forename: M D
authors.initials: MD
authors.lastname: Mudry
authors.forename: M
authors.initials: M
authors.lastname: Rahn
authors.forename: M
authors.initials: M
authors.lastname: Gorostiaga
authors.forename: A
authors.initials: A
authors.lastname: Hick
authors.forename: M S
authors.initials: MS
authors.lastname: Merani
authors.forename: A J
authors.initials: AJ
authors.lastname: Solari
mesh_terms: D000508:Alouatta / Q000235:genetics*; D000818:Animals; D002871:Chromosome Banding; D007621:Karyotyping; D008297:Male; D013090:Spermatocytes / Q000648:ultrastructure; D013573:Synaptonemal Complex