Methylenetetrahydrofolate reductase (MTHFR) allele frequencies in Amerindians.

Neural tube defects (NTDs) have been associated with abnormalities of folate metabolism. Methylenetetrahydrofolate reductase (MTHFR) is the regulatory enzyme for the conversion of homocysteine to methionine. The C677T mutation in the MTHFR gene affects folate distribution, and homozygosity for the T allele may be associated with an increased risk of NTDs.

Y-chromosome evidence for differing ancient demographic histories in the Americas.

To scrutinize the male ancestry of extant Native American populations, we examined eight biallelic and six microsatellite polymorphisms from the nonrecombining portion of the Y chromosome, in 438 individuals from 24 Native American populations (1 Na Dené and 23 South Amerinds) and in 404 Mongolians. One of the biallelic markers typed is a recently identified mutation (M242) characterizing a novel founder Native American haplogroup. The distribution, relatedness, and diversity of Y lineages in Native Americans indicate a differentiated male ancestry for populations from North and South America, strongly supporting a diverse demographic history for populations from these areas.

A first molecular phylogenetic analysis of Passiflora (Passifloraceae).

Passiflora, a genus with more than 400 species, exhibits a high diversity of floral and vegetative structures and a complex taxonomy, which includes 23 subgenera and many sections and series. To better understand Passiflora's variability and interspecific relationships, the phylogeny of 61 species, classified in 11 of 23 suggested subgenera, was investigated. Three molecular markers were used, the nuclear ribosomal internal transcribed spacers (nrITS), the plastid trnL-trnF spacer regions (∼1000 bp), and the rps4 plastid gene (∼570 bp).

Low levels of STRP variability are not universal in American Indians.

Data related to 15 short tandem repeat polymorphisms (STRPs) are reported for five Brazilian Indian populations, and a set of them compared with results previously reported for Asian, neo-Brazilian, North American, Iberian, and African populations. The low variability observed for these markers among the Suruí Indians is confirmed, but the other populations show variability levels that are similar to those found elsewhere. Previous suggestions of population bottlenecks in the prehistorical colonization of the New World were not confirmed.

Y-chromosome biallelic polymorphisms and Native American population structure.

It has been proposed that women had a higher migration rate than men throughout human evolutionary history. However, in a recent study of South American natives using mtDNA restriction fragment polymorphisms and Y-chromosome microsatellites we failed to detect a significant difference in estimates of migration rates between the sexes. As the high mutation rate of microsatellites might affect estimates of population structure, we now examine biallelic polymorphisms in both mtDNA and the Y-chromosome.

Polymorphisms of CYP1a1, CYP2e1, GSTM1, GSTT1, and TP53 genes in Amerindians.

Polymorphisms at the TP53, cytochrome P-450 (CYP), and glutathione S-transferase (GST) genes are related to cancer susceptibility and present high diversity in allele frequencies among ethnic groups. This study concerns the CYP2E1, GSTM1, and GSTT1 polymorphisms in seven Amerindian populations (Xavante, Guarani, Aché, Wai Wai, Zoró, Surui, and Gavião). Polymorphic sites at CYP1A1 and TP53 were also studied in the Aché and Guarani tribes and compared with previous results about these systems already obtained in the other populations.

Distribution of CGG repeats and FRAXAC1/DXS548 alleles in South American populations.

In order to assess the molecular variability related to fragile X (FMR1 locus), we investigated the distribution of CGG repeats and DXS548/FRAXAC1 haplotypes in normal South American populations of different ethnic backgrounds. Special attention was given to Amerindian Wai-Wai (Northern Brazil) and Ache (Paraguay), as well as to Brazilian isolated communities of African ancestry, the remnants of quilombos. Comparison of samples from quilombos, Amerindians, and the ethnically mixed, but mainly European-derived population of São Paulo revealed that the 30-copy allele of the fragile X gene is the most frequent in all groups.

Lipoprotein lipase and APOE/APOC-I/APOC-II gene cluster diversity in native Brazilian populations.

Allele and haplotype frequencies for the T-93G, Hind III, and Pvu II variants of the lipoprotein lipase gene (LPL), and Hpa I and Ava II restriction site polymorphisms (RSP) of the APOE/C-I/C-II gene cluster were determined in 143 individuals from five Brazilian Indian tribes. These results were integrated with those previously reported for APOE. Marked interethnic variability occurs in these sites.

Molecular variability in Amerindians: widespread but uneven information.

A review was made in relation to the molecular variability present in North, Central, and South American Indian populations. It involved results from ancient DNA, mitochondrial DNA in extant populations, HLA and other autosomal markers, X and Y chromosome variation, as well as data from parasitic viruses which could show coevolutionary changes. The questions considered were their origin, ways in which the early colonization of the continent took place, types and levels of the variability which developed, peculiarities of the Amerindian evolutionary processes, and eventual genetic heterogeneity which evolved in different geographical areas.

Alu insertions versus blood group plus protein genetic variability in four Amerindian populations.

Background: Do the population relationships obtained using DNA or blood group plus protein markers remain the same or do they reveal different patterns, indicating that the factors which influence genetic variation at these two levels of analysis are diverse? Can these markers shed light on the biological classification of the Aché, a Paraguayan tribe which only recently established more permanent contacts with non-Indians?

Subjects And Methods: To consider these questions we typed 193 individuals from four Amerindian tribes in relation to 12 Alu polymorphisms (five of them never studied in these populations), while 22 blood group plus protein systems were studied among the Aché. These data were then integrated with those previously available (blood groups plus proteins) for the three other populations. DNA extraction and amplification, as well as the other laboratory procedures, were performed using standard methods currently in use in our laboratory.

Unequal contributions of male and female gene pools from parental populations in the African descendants of the city of Melo, Uruguay.

In admixed populations, genetic contributions from males and females of specific parental populations can be of different proportions due to past directional mating during the process of genetic admixture. In this research paper, we provide evidence of such male- and female-specific differential admixture components of African, European, and American Indian origin in an admixed population from the city of Melo, in the northeastern region of Uruguay. From data on 11 autosomal markers from a sample of 41 individuals of mixed African descent, we estimated 47% African, 38% European, and 15% Amerindian contributions.

Genetic, geographic, and linguistic variation among South American Indians: possible sex influence.

To better understand the relationship between genetic variability, geographical distance, and linguistic affiliation in South Amerinds, and to elucidate whether the migration rate is the same for both sexes, spatial autocorrelation, Mantel's test, and F(ST) analyses were performed in four sets of populations and alleles (group 1: 48 populations, 12 alleles; group 2: 16 (all belonging to the Tupi linguistic group) and 12; group 3: 21 and 17; and group 4: 28 and 4 haplotypes). Groups 1-3 included blood group and protein (i.e.

Haplotype and allele frequencies for three genes of the dopaminergic system in South American Indians.

Haplotype and allele frequencies for the dopamine D2 receptor gene (DRD2), dopamine D4 receptor gene (DRD4), and dopamine transporter protein gene (SLC6A3) were determined in 135 individuals from five Brazilian Indian tribes, and the results integrated with those previously presented for this ethnic group. DRD2 and DRD4 were highly polymorphic. Haplotypes including TaqI A1 at DRD2, and the seven repeat allele at DRD4 were the most frequent variants, while the SLC6A3 locus was monomorphic for the 10 repeat allele in South American Indians.

African-derived South American populations: A history of symmetrical and asymmetrical matings according to sex revealed by bi- and uni-parental genetic markers.

Estimates of African, European, and Amerindian contributions to the gene pool of 11 predominantly African-derived South American populations were obtained using five autosomal and one Y chromosome hypervariable loci, as well as mitochondrial DNA (sequences of the first hypervariable segment of the control region, plus two restriction sites and the presence or absence of the CoII/tRNA(Lys) intergenic 9-bp deletion). The three latter characteristics are reported here for the first time for 42 individuals living in three Brazilian populations. Thirty-eight sequences were identified in these persons; 17 (45%) could be classified as being of African, 4 (11%) of Amerindian, and 2 (5%) of European origin.

Albumin genetic variability in South America: Population distribution and molecular studies.

A total of 5,020 individuals living in two southern Brazilian states were screened in relation to albumin types; two variants were found, in Passo Fundo (Nagasaki 2) and Vera Cruz (Tradate 2). Another variant, detected in the northeast, was identified as Porto Alegre 2, which also occurs in other places in Brazil, as well as in India, Pakistan, and Turkey. The results were integrated with those obtained in other studies in South America, yielding a total of 16,941 Amerindians and 23,839 non-Indian subjects.

New genetic data on Amerindians from the Paraguayan Chaco.

New data on 17 blood group and protein genetic systems obtained among the Ayoreo and Lengua Indians of Paraguay are presented. They include the first report on the red cell band-3 protein investigated among South American Indians. This information was integrated with previous results available for these two and four other groups.

Blood pressure levels in Xavánte adults from the Pimentel Barbosa Indian Reservation, Mato Grosso, Brazil.

Objective: To study blood pressure (BP) levels in the Xavánte Indians of Central Brazil.

Methods: 93 subjects > or = 15 years old were included. Systolic (SBP) and diastolic (DBP) blood pressure readings were taken to the nearest mm Hg at Korotkoff phases 1 and 5 using a mercury sphygmomanometer.

Genetic relationships between Amerindian populations of Argentina.

A total of 495 individuals from five different Argentinian tribes was examined for variation in 23 blood group and protein genetic systems, and the results were integrated with previous data on some of these systems. These tribes generally present RH * R1, PGM1 * 1, and ACP * A frequencies lower and RH * R2, ESD * 1, and GLO * 1 prevalences higher than those observed in other South American Indian groups. Earlier studies with mitochondrial DNA showed that haplogroup A was present in low frequencies in these tribes, but haplogroup B showed a high prevalence among the Mataco.

TP53 polymorphisms and haplotypes in South Amerindians and neo-Brazilians.

To evaluate the genetic diversity of Brazilian populations and contribute to the knowledge of their evolutionary history this study investigated three TP53 polymorphisms (BstUI and MspI RFLPs in exon 4 and intron 6, respectively, and a 16 bp duplication in intron 3). The populations studied were: 114 Amerindians from five Brazilian Indian tribes (Gavião, Surui, Zoró, Wai-Wai and Xavante), 95 Euro-Brazilians and 70 Afro-Brazilians. The polymorphisms were all analysed using PCR amplifications.

Diversity of two short tandem repeat loci (CD4 and F13A1) in three Brazilian ethnic groups.

Two microsatellites (CD4 and F13A1) were investigated in seven Brazilian populations: one group each of European- and African-derived subjects from Porto Alegre, southern Brazil, and five Amerindian tribes (three Tupi-Mondé speaking [Gavião, Surui, and Zoró], one Macro-Gê [Xavante], and one Carib [Wai-Wai]). For both markers, neo-Brazilians presented with a high diversity, but Amerindians showed a low level of variability. Genotype frequency distributions were heterogeneous among populations, the only exception being similar CD4 frequencies in Afro- and Euro-Brazilians.

Cytochrome P4501A1 polymorphisms in South American Indians.

A total of 131 individuals from five Brazilian Indian tribes were studied for two CYP1A1 gene polymorphisms. The presence of the *val allele at codon 462 varied from 54% in the Surui to 97% in the Xavante, while the presence of the MspI restriction site (*m2 allele) at position T6235C ranged from 72% in the Gavião to 95% in the Xavante. The haplotypes derived from these two sites showed a highly heterogeneous distribution among the five populations.

[Mucociliary clearance after aerobic exertion in athletes].

The Authors studied the modifications in nasal mucociliary clearance times before and after aerobic exertion in athletes. A total of 60 athletes with high-level training (age range 18-37 years) were selected for this study. Persons who smoked or had allergies, nasal sinus phlogosis or tumors, altered nasal cavity morphology (i.

Association of the low-density lipoprotein receptor gene with obesity in Native American populations.

Five low-density lipoprotein receptor gene (LDLR) restriction fragment length polymorphisms (RFLPs: TaqI, intron 4; HincII, exon 12; AvaII, exon 13; MspI and NcoI, exon 18) were investigated in 131 individuals from five Brazilian Indian tribes. All markers were polymorphic in this ethnic group. In the whole sample of Amerindians, 13 (41%) of the 32 expected haplotypes were identified, but only three were shared by all tribes.