Genetic and morphological variability in South American rodent Oecomys (Sigmodontinae, Rodentia): evidence for a complex of species.

The rodent genus Oecomys (Sigmodontinae) comprises ~16 species that inhabit tropical and subtropical forests in Central America and South America. In this study specimens of Oecomys paricola Thomas, 1904 from Belém and Marajó island, northern Brazil, were investigated using cytogenetic, molecular and morphological analyses. Three karyotypes were found, two from Belém (2n = 68, fundamental number (FN) = 72 and 2n = 70, FN = 76) and a third from Marajó island (2n = 70, FN = 72). No molecular or morphological differences were found between the individuals with differing cytotypes from Belém, but differences were evident between the individuals from Belém and Marajó island. Specimens from Belém city region may represent two cryptic species because two different karyotypes are present in the absence of significant differences in morphology and molecular characteristics. The Marajó island and Belém populations may represent distinct species that have been separated for some time, and are in the process of morphological and molecular differentiation as a consequence of reproductive isolation at the geographic and chromosomal levels. Thus, the results suggest that O. paricola may be a complex of species.

Fate of a redundant gamma-globin gene in the atelid clade of New World monkeys: implications concerning fetal globin gene expression.

Conclusive evidence was provided that gamma 1, the upstream of the two linked simian gamma-globin loci (5'-gamma 1-gamma 2-3'), is a pseudogene in a major group of New World monkeys. Sequence analysis of PCR-amplified genomic fragments of predicted sizes revealed that all extant genera of the platyrrhine family Atelidae [Lagothrix (woolly monkeys), Brachyteles (woolly spider monkeys), Ateles (spider monkeys), and Alouatta (howler monkeys)] share a large deletion that removed most of exon 2, all of intron 2 and exon 3, and much of the 3' flanking sequence of gamma 1. The fact that two functional gamma-globin genes were not present in early ancestors of the Atelidae (and that gamma 1 was the dispensible gene) suggests that for much or even all of their evolution, platyrrhines have had gamma 2 as the primary fetally expressed gamma-globin gene, in contrast to catarrhines (e.g., humans and chimpanzees) that have gamma 1 as the primary fetally expressed gamma-globin gene. Results from promoter sequences further suggest that all three platyrrhine families (Atelidae, Cebidae, and Pitheciidae) have gamma 2 rather than gamma 1 as their primary fetally expressed gamma-globin gene. The implications of this suggestion were explored in terms of how gene redundancy, regulatory mutations, and distance of each gamma-globin gene from the locus control region were possibly involved in the acquisition and maintenance of fetal, rather than embryonic, expression.

Divergence between biochemical and cytogenetic differences in three species of the Callicebus moloch group.

Specimens from three species of the Callicebus moloch group--C. moloch (N = 80), C. brunneus (N = 166), and C. cupreus (N = 23)--were studied. Twenty genetic loci were investigated through electrophoresis, genetic distances were estimated, and the results compared with the available cytogenetic data. Low values of genetic distance were encountered, contrasting with relatively large chromosome differences. We propose that recent karyotypic rearrangements, rather than other Pleistocene events, were the major evolutionary mechanisms determining speciation in these three taxa.

Evaluation of the physical fitness by the Bruno Balke protocol in sedentary and wheelchair trained paraplegic patients.

The Bruno Balke test is one of the methods available to measure the oxygen intake in wheelchair users. The equation of the test is:intake O2 = 33+ (speed average-133) x 0.17 ml/kg x min. (-1). The average speed represents the acceleration and may be used to measure the level of physical fitness. In order to verify the efficiency of this kind of evaluation, we selected ten male, sedentary paraplegic patients, level D5-D12 in an ordinary rehabilitation program and ten paraplegic athletes. All of them were submitted to the Bruno Balke test. The results demonstrated that the average speed, the covered distance and the oxygen intake were significantly greater in athletes than in sedentary individuals.

Coat color and biochemical variation in Amazonian wild populations of Alouatta belzebul.

A comparative study of 13 blood genetic systems and pelage color variation was performed in four wild populations of Alouatta belzebul. The animals from the west bank of the Tocantins River showed less color variation than those from the east bank, as well as less than those from Tocantins Island. The blood genetic markers, however, revealed an opposite pattern of variation. A previously undescribed morphological variant (completely red) was observed in one specimen of the east bank, where pelage color of the local population varied from completely black to completely red. Levels of heterozygosity and inter- and intralocus variances for the blood systems are compared with those observed in five other species of New World primates.

Genetic variability in a natural population of Cebus apella paraguayanus (Cebidae, primates)

Foram estudadas 17 proteínas séricas e eritrocitárias em uma populaçäo natural de Cebus apella paraguayanus. Apenas o locus da GPI mostrou poliformismo (GPI*1 = 89% and GPI*2 = 11%). Uma análise comparativa das estimativas de variabilidade genética dentre os primatas mostrou que C. a paraguayanus (P = 5.9%; H = 1.1%) apresenta níveis de variaçäo genética comparáveis a Alouatta palliata e Leontopithecus rosalia, duas outras espécies do Novo Mundo

Esterase D in Cebus apella from the Amazonian region.

Research programs involving the study of genetic variation of proteins have been carried out both in humans and catarrhine primates but rarely in New World species. Considering the great possibilities offered by protein variations as genetic markers in systematic and evolutionary studies in this group of organisms, the authors are specially interested in the investigation of genetic polymorphisms of blood proteins in Amazonian primates. In this paper we describe the electrophoretic patterns of erythrocyte esterases obtained from blood samples of 57 Cebus apella specimens. Blood hemolysates from Cebus display four main set of bands in azo-coupled stained gels. These bands are identified as esterases P, A1, A2 and B by their electrophoretic migration, substrate specificity and eserine reaction. The use of the fluorogenic reagent 4-methylumbelliferyl acetate revealed the presence of a fifth set of enzymes not detected by the azo-coupled staining method. This set of enzymes, probably a polymorphic genetic system, was named ESD as in humans.