Chromosoma (2004) 113: 305–315 DOI 10.1007/s00412-004-0320-6 RESEARCH ARTICLE R. Stanyon . F. Bigoni . T. Slaby . S. Muller . G. Stone . C. R. Bonvicino . M. Neusser . H. N. Seuánez Multi-directional chromosome painting maps homologies between species belonging to three genera of New World monkeys and humans Received: 11 August 2004 / Revised: 17 September 2004 / Accepted: 27 September 2004 / Published online: 13 November 2004 # Springer-Verlag 2004 Abstract We mapped chromosomal homologies in two species of Chiropotes (Pitheciini, Saki Monkeys) and one species of Aotus (Aotinae, Owl Monkey) by multi- directional chromosome painting. Human chromosome probes were hybridized to Chiropotes utahicki, C. israelita and Aotus nancymae metaphases. Wooly Monkey chro- mosome paints were also hybridized to Owl Monkey metaphases. We established Owl Monkey chromosome paint probes by flow sorting and reciprocally hybridized them to human chromosomes. The karyotypes of the Bearded Saki Monkeys studied here are close to the hypothesized ancestral platyrrhine karytoype, while that of the Owl Monkey appears to be highly derived. The A. nancymae karyotype is highly shuffled and only three human syntenic groups were found conserved coexisting with 17 derived human homologous associations. A minimum of 14 fissions and 13 fusions would be required to derive the A. nancymae karyotype from that of the ancestral New World primate karyotype. An inversion between homologs to segments of human 10 and 16 suggests a link between Callicebus and Chiropotes, while the syntenic association of 10/11 found in Aotus and Callicebus suggests a link between these two genera. Future molecular cytogenetic work will be needed to determine whether these rearrangements represent syna- pomorphic chromosomal traits. Introduction Over the last decade, many New World (NW) primates (Platyrrhini) were studied using molecular cytogenetic methods such as cross-species chromosome painting. However, of the major taxonomic divisions of Platyrrhini, data are totally lacking for species of the subfamily Aotinae (Owl or Night monkeys) and the tribe Pitheciini (Saki and Uakari monkeys). This report will fill this lacuna in primate genome evolution by studying, with multi- directional chromosome painting, the karyotypes of two species of Chiropotes (Pitheciini) and one species of Aotus (Aotinae). Cytogenetic data in combination with other bio-mor- phological indicators in NW monkeys have contributed vital data for the recognition of several extant species within taxa previously considered monotypic. The pre- viously monotypic genus Aotus is a good example. The discovery of previously unappreciated phenotypic differ- ences and, especially, a wide variety of karyotypes justified the recognition of several species. Karyological studies, extensively carried out by Ma and her co-workers, showed 11 different karyotypes (Ma 1981; Ma et al. 1976, 1978, 1985). More recent reports of Colombian specimens (Torres et al. 1998) indicated that the diploid chromosome number in Aotus ranges from 2n=46 to 59. Hershkovitz (1983) listed nine species of Aotus, while Rylands (2000) and Groves (2001) recognized eight; probably the true Communicated by E. Nigg R. Stanyon (*) . F. Bigoni . T. Slaby . G. Stone Comparative Molecular Cytogenetics Core, BRL, National Cancer Institute-Frederick, Frederick, MD, USA e-mail: stanyonr@ncifcrf.gov T. Slaby Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA S. Muller . M. Neusser Institute of Anthropology and Human Genetics, Department of Biology II, Ludwig-Maximilians University of Munich, Munich, Germany C. R. Bonvicino . H. N. Seuánez Division of Genetics, Instituto Nacional de Câncer, Rio de Janeiro, Brazil C. R. Bonvicino Department of Tropical Medicine, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil H. N. Seuánez Department of Genetics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil