The cotton-top tamarin (CTT) (Sagiunus oedipus) has been used as an animal model to investigate the etiology and pathophysiology of several human diseases, including ulcerative colitis and ifs associated colorectal carcinoma (CRC). Little is known, however, about genetic synteny between CTT and humans, and about chromosome aberrations in CTT CRC. To address these issues, we have analyzed CTT lymphoblastoid and CRC cell lines using cytogenetics, fluorescence in situ hybridization (Zoo-FISH), and direct sequencing. The CTT lymphocytes had pseudodiploid chromosomes of 46. The CTT CRC cells showed near-diploid chromosomes of 45. Several clonal structural aberrations were observed, including der(1), a marker chromosome, and double minutes. Zoo-FISH using human chromosome 2, 3, 5, 6, 9, 11, 13, 15, 16, 17, 19, 22, and X paints identified homologous chromosomes and subchromosomal regions in the CTT genome. Fluorescence in situ hybridization with human telomeric probe also detected a homologous sequence in CTT genome. Direct sequencing of CTT genomic DNA using primers amplifying exons 4 and 25 of the human APC gene identified DNA sequences in CTT genome with 99% and 95% homology, respectively. These results provide a basis for further comparative studies of CTT and human genome. (C) 2000 Elsevier Science Inc. All rights reserved.