Sidney E. B. Santos

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It is well accepted that the Americas were the last continents reached by modern humans, most likely through Beringia. However, the precise time and mode of the colonization of the New World remain hotly disputed issues. Native American populations exhibit almost exclusively five mitochondrial DNA (mtDNA) haplogroups (A-D and X). Haplogroups A-D are also(More)
The mitochondrial DNA (mtDNA) of 139 individuals from eight tribes which belong to four linguistic groups of the Brazilian Amazon Region was studied both by RFLP and by sequencing of the D-loop region. RFLP analysis showed that 41 haplotypes (29%) belonged to haplogroup A, 39 (28%) to haplogroup B, 38 (27%) to haplogroup C, 19 (14%) to haplogroup D, and 2(More)
Estimating the proportions of different ancestries in admixed populations is very important in population genetics studies, and it is particularly important for detecting population substructure effects in case-control association studies. In this work, a set of 48 ancestry-informative insertion-deletion polymorphisms (INDELs) were selected with the goal of(More)
Insertion/deletion (INDEL) polymorphisms are diallelic markers with potential characteristics for use in forensics and biological anthropology, including: the simplicity of laboratory analysis, the possibility of genotyping many markers in a single PCR multiplex reaction, as well as analyzing markers with special inheritance types, such as those linked to(More)
Recently a novel polymorphism in the 3'-untranslated region of the prothrombin gene (a G to A transition at position 20210) was discovered, and an association with venous thrombosis and cardiovascular disease was found. The prevalence of the polymorphic allele in different human populations is unknown. We investigated the prevalence of the A 20210 allele of(More)
There is general agreement that the Native American founder populations migrated from Asia into America through Beringia sometime during the Pleistocene, but the hypotheses concerning the ages and the number of these migrations and the size of the ancestral populations are surrounded by controversy. DNA sequence variations of several regions of the genome(More)
Lectins from eight leguminous seeds from the Diocleae tribe were compared to Concanavalin A (Con A), a well known T cell mitogen, on the stimulation of lymphocyte proliferation and Interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) from normal volunteers. Lectins from Canavalia brasiliensis and Dioclea virgata induced the(More)
BACKGROUND AND OBJECTIVES Platelet-specific alloantigens are important in neonatal alloimmune thrombocytopenia, posttransfusion purpura, refractoriness to platelet transfusions, and population genetics. Data are scarce on allele frequencies in ethnic groups other than whites and Asians. MATERIALS AND METHODS Using allele-specific restriction enzyme(More)
A recurrent partial azoospermia factor C (AZFc) deletion, called gr/gr, has been reported to be a male infertility risk factor. A specific type of Y chromosome observed in approximately 30% of Japanese males (haplogroup D derived at YAP+) is believed to have a fixed gr/gr deletion. A recent study claimed that spermatogenic failure is more likely in males(More)
BACKGROUND AND OBJECTIVES Amerindians are blood group O, but the distribution of the various O alleles is unknown. Their ABO genotypes were compared with samples from other Brazilian ethnic groups. MATERIALS AND METHODS Genomic DNA was examined by PCR-RFLP analysis, PCR-SSP and direct sequencing. RESULTS An unusual allele distribution was found, with(More)