Evguenia Alechine

Continent-Wide Decoupling of Y-Chromosomal Genetic Variation from Language and Geography in Native South Americans

Numerous studies of human populations in Europe and Asia have revealed a concordance between their extant genetic structure and the prevailing regional pattern of geography and language. For native South Americans, however, such evidence has been lacking so far. Therefore, we examined the relationship between Y-chromosomal genotype on the one hand, and male geographic origin and linguistic affiliation on the other, in the largest study of South American natives to date in terms of sampled individuals and populations. A total of 1,011 individuals, representing 50 tribal populations from 81 settlements, were genotyped for up to 17 short tandem repeat (STR) markers and 16 single nucleotide polymorphisms (Y-SNPs), the latter resolving phylogenetic lineages Q and C. Virtually no structure became apparent for the extant Y-chromosomal genetic variation of South American males that could sensibly be related to their inter-tribal geographic and linguistic relationships. This continent-wide decoupling is consistent with a rapid peopling of the continent followed by long periods of isolation in small groups. Furthermore, for the first time, we identified a distinct geographical cluster of Y-SNP lineages C-M217 (C3*) in South America. Such haplotypes are virtually absent from North and Central America, but occur at high frequency in Asia. Together with the locally confined Y-STR autocorrelation observed in our study as a whole, the available data therefore suggest a late introduction of C3* into South America no more than 6,000 years ago, perhaps via coastal or trans-Pacific routes. Extensive simulations revealed that the observed lack of haplogroup C3* among extant North and Central American natives is only compatible with low levels of migration between the ancestor populations of C3* carriers and non-carriers. In summary, our data highlight the fact that a pronounced correlation between genetic and geographic/cultural structure can only be expected under very specific conditions, most of which are likely not to have been met by the ancestors of native South Americans.

Where is the game? Wild meat products authentication in South Africa: a case study

BackgroundWild animals’ meat is extensively consumed in South Africa, being obtained either from ranching, farming or hunting. To test the authenticity of the commercial labels of meat products in the local market, we obtained DNA sequence information from 146 samples (14 beef and 132 game labels) for barcoding cytochrome c oxidase subunit I and partial cytochrome b and mitochondrial fragments. The reliability of species assignments were evaluated using BLAST searches in GenBank, maximum likelihood phylogenetic analysis and the character-based method implemented in BLOG. The Kimura-2-parameter intra- and interspecific variation was evaluated for all matched species.ResultsThe combined application of similarity, phylogenetic and character-based methods proved successful in species identification. Game meat samples showed 76.5% substitution, no beef samples were substituted. The substitutions showed a variety of domestic species (cattle, horse, pig, lamb), common game species in the market (kudu, gemsbok, ostrich, impala, springbok), uncommon species in the market (giraffe, waterbuck, bushbuck, duiker, mountain zebra) and extra-continental species (kangaroo). The mountain zebra Equus zebra is an International Union for Conservation of Nature (IUCN) red listed species. We also detected Damaliscus pygargus, which is composed of two subspecies with one listed by IUCN as ‘near threatened’; however, these mitochondrial fragments were insufficient to distinguish between the subspecies. The genetic distance between African ungulate species often overlaps with within-species distance in cases of recent speciation events, and strong phylogeographic structure determines within-species distances that are similar to the commonly accepted distances between species.ConclusionsThe reliability of commercial labeling of game meat in South Africa is very poor. The extensive substitution of wild game has important implications for conservation and commerce, and for the consumers making decisions on the basis of health, religious beliefs or personal choices.Distance would be a poor indicator for identification of African ungulates species. The efficiency of the character-based method is reliant upon availability of large reference data. The current higher availability of cytochrome b data would make this the marker of choice for African ungulates. The encountered problems of incomplete or erroneous information in databases are discussed.

A DNA extraction method of small quantities of bone for high-quality genotyping.

DNA genotyping techniques have been used successfully in forensic science for almost three decades and represent the gold standard for individual identification. However, efficient protocols for obtaining DNA from exhumed bones suitable for genotyping are still scarce and most of them require a considerable amount of starting material, are time consuming and are inefficient for reducing inhibitors effects. We sought to develop an optimised protocol for extracting DNA from bone samples obtained from exhumations. We tested two approaches for preparing bone samples: (a) fine powder and (b) thin slices of bone. The best ratio of bone amount to DNA yields was assessed by a titration experiment using bone powder ranging from 50 to 1000mg. We obtained optimal DNA yields (27pg mg(-1) on average) when 150-200mg of starting material were processed using a one-step demineralisation method. Better-quality profiles (determined by the number of genotyped loci) were obtained when DNA was extracted from bone slices compared to extraction from bone powder. From bone slices 83.9% and from bone powder 46.7% of the samples provided genotypes for 11 or more loci. Since bone preparation procedures were carried out at room temperature, the method developed in the present study might be an attractive alternative to the standard freeze-mill approach, being faster and more cost-efficient.

Rapid screening for Native American mitochondrial and Y-chromosome haplogroups detection in routine DNA analysis

Aiming to detect individuals of Native American maternal or paternal ancestry a rapid screening approach has been developed. Its strategy was based on SNP typing by Real Time PCR (rt-PCR) followed by High Resolution Melting analysis (HRM). After extraction, DNA was quantitated by rt-PCR using commercial kits; samples were then submitted to two multiplex reactions in order to determine the major Native American mtDNA and Y-chromosome haplogroups by HRM. One cocktail included primers flanking nucleotide substitutions that define mtDNA haplogroup C and sub-haplogroups A2, B2, and D1. The other included primers flanking Y-SNPs M3, M269 and U179 that allowed discriminating Q and non-Q haplogroups. In all cases amplicons were <125 nucleotides long in order to increase the peak resolution. The accuracy of the results obtained was established by means of sequencing analysis of the amplicons. The new working-flow here proposed facilitates and speeds-up the screening process that may preclude a detailed sequencing analysis of particular samples, or for further molecular epidemiological investigations in which continental origin influences might be relevant.

Development of a quantitation approach for total human and male DNA based on Real Time PCR followed by High Resolution Melting analysis

We developed and validated a total human DNA quantitation technique that simultaneously allows male DNA detection. This assay, called Amel‐Y, is a duplex Real Time PCR followed by HRM (high resolution melting) analysis using the intercalating dye SYTO9. Amel‐Y duplex produces two amplicons, one for the amelogenin gene (106/112 bp, female/male) and another (84 bp) corresponding to human Y chromosome‐specific fragment to detect male DNA. After HRM analysis, two melting peaks differing in 5.3°C–5.5°C are detected if both male and female DNA are present and only one if only female DNA is present. For specificity assessment, the inclusion of high concentrations of bacterial and fungal DNA in the quantitation reactions allowed discarding species cross‐reactivity. A set of crime scene evidence from forensic casework has been quantified with commercial kits and compared with Amel‐Y duplex. Our method detected male DNA from a concentration of 18 pg/μL and supports autosomal/Y DNA detection ratio up to 200:1. A limitation of the technique is its inability to quantify male and female donnors in a mixed sample. The Amel‐Y duplex demonstrated to be an efficient system for quantifying total human DNA being a specific, rapid, sensitive, and cost‐effective method suitable for mixed DNA samples and applicable to any field where human DNA quantification is required, such as molecular diagnosis, population genetics, and forensic identification.

Analysis of D216H polymorphism in Argentinean patients with primary dystonia.

Abstract The D216H polymorphism (rs1801968) in TOR1A has been suggested as a risk factor for developing primary dystonia in German subjects not carrying the deletion c.904-906delGAG (∆GAG). However, this association could not be confirmed in other populations with different ethnic backgrounds. The purpose of this study is to evaluate the D216H polymorphism in an Argentinean cohort of 40 patients with primary dystonia and 200 unrelated control subjects. The authors could observe a significantly higher frequency of the H216 variant in dystonic patients lacking ∆GAG as compared with controls.

Sample selection bias in an international DNA panel: does Native American haplogroup Q-M3 has the b2/b3 deletion?

Fil: Alechine, Evguenia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Servicio de Huellas Digitales Geneticas; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina