Different kinds of constitutive heterochromatin variation were observed in 72 specimens of Cebus apella, belonging to five distinct subspecies, captured in four geographic regions of South America. One particular chromosome type, affecting pair 19, was found to be exclusive of one subspecies (Cebus apella paraguayanus) and to have a distribution significantly different from that expected at equilibrium. Conversely, some other chromosome polymorphisms were more widespread, with distributions compatible with equilibrium. Other variant types, probably resulting from paracentric inversions involving both heterochromatin and euchromatin, were rarer and restricted to single specimens. Finally, a distinctive chromosome type 11 was found to be exclusive of one subspecies (Cebus apella xanthosternos), where it appeared as a fixed trait.
Callimico goeldii (Goeldi's marmoset) is a neotropical primate with 2n = 47,X1X2Y in the male, and 2n = 48,X1X1X2X2 in the female, due to a Y-autosome translocation. Karyological comparisons of Callimico, Callithrix jacchus and Cebus apella suggest that Callimico is a member of the Callitrichidae. Isozyme data and restriction mapping of LINE-1 repetitive elements in these species and in a variety of other neotropical primates confirm these findings and supply strong evidence for including Callimico in the Callitrichidae.
Chromosome studies were performed on 40 specimens identified as Cebus apella paraguayanus, Fischer, 1829, which had been wild-caught in Santa Catalina (Republic of Paraguay). Elongated chromosome spreads obtained from lymphocyte cultures were sequentially stained with different techniques, and a constant pattern of 382 bands was identified in all specimens. A standard karyotype based on the measurements of the total chromosome length and the G-Q banding pattern is proposed.
During the years 1975-1987, 1,364 cytogenetic studies were performed in 682 couples with history of adverse pregnancy outcome. Thirty-six balanced translocations were detected, 24 (3.5%) in women and 12 (1.7%) in men. Before 1982, all 234 couples studied had 2 or more spontaneous abortions with unknown pedigrees, with an incidence of 6.8% of balanced translocations. During 1982-1987, complete pedigree analysis was performed on a subset of 448 couples, who were then classified into 3 groups. Group I; 321 couples with 2 or more spontaneous abortions, but no other adverse outcome; group II; 37 couples with at least one or more spontaneous abortions plus a malformed child or stillbirth; and group III; 90 couples with one or more spontaneous abortions plus a sib having at least a malformed child or repetitive spontaneous abortions. The incidence of balanced translocations in these 3 groups was 2.8%, 5.4%, and 10.0%, respectively. When group III was compared with group I, the frequency of translocations was significantly different (P less than 0.02). Robertsonian translocations were predominantly detected in women, raising the possibility that prezygotic failure producing primary sterility may occur in men with such translocations.
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