La genètica de les migracions humanes: Seguint el rastre de les migracions a través del nostre genoma

La reconstrucció de les migracions humanes és possible gràcies a la informació aportada per diverses disciplines. L’estudi de la diversitat genètica de les poblacions humanes actuals ens revela quins han estat els esdeveniments demogràfics i moviments migratoris passats que han deixat una empremta en el nostre genoma

Complint una intuïció de Darwin: genètica humana i llengües

Les similituds entre la manera com s'hereten i evolucionen els gens i les llengües han promogut l'interès en l'anàlisi conjunta d'ambdós camps. La correlació entre gens i llengües va ser demostrada per primer cop per Cavalli-Sforza i col·laboradors en comparar un arbre construït amb marcadors genètics clàssics amb un arbre lingüístic de les llengües. S'han formulat diverses crítiques a aquest mètode, i se n'han descrit nombroses excepcions. S'ha demostrat que el factor més important que determina la correlació de gens i llengües és la geografia. Nogensmenys, la informació proporcionada per la genètica i la lingüística, ensems amb la proporcionada per altres disciplines, ens permetrà reconstruir la història de la humanitat.The similarities between the mode of inheritance and evolution of genes and languages have fostered interest in the joint analysis of both disciplines. The correlation between genes and languages was firstly demonstrated by Cavalli-Sforza and collaborators comparing a tree build from ‘classical’ genetic markers to a linguistic tree of languages. Several criticisms to this correlation have been raised and a large number of exceptions have been described. It has been shown that the most plausible factor that influences in the correlation of genes and languages is geography. However, the information provided by genetics and linguistics, as well as the one provided by other disciplines, will allow us to reconstruct the history of humankind

Genome-Wide and Paternal Diversity Reveal a Recent Origin of Human Populations in North Africa.

The geostrategic location of North Africa as a crossroad between three continents and as a stepping-stone outside Africa has evoked anthropological and genetic interest in this region. Numerous studies have described the genetic landscape of the human population in North Africa employing paternal, maternal, and biparental molecular markers. However, information from these markers which have different inheritance patterns has been mostly assessed independently, resulting in an incomplete description of the region. In this study, we analyze uniparental and genome-wide markers examining similarities or contrasts in the results and consequently provide a comprehensive description of the evolutionary history of North Africa populations. Our results show that both males and females in North Africa underwent a similar admixture history with slight differences in the proportions of admixture components. Consequently, genome-wide diversity show similar patterns with admixture tests suggesting North Africans are a mixture of ancestral populations related to current Africans and Eurasians with more affinity towards the out-of-Africa populations than to sub-Saharan Africans. We estimate from the paternal lineages that most North Africans emerged ~15,000 years ago during the last glacial warming and that population splits started after the desiccation of the Sahara. Although most North Africans share a common admixture history, the Tunisian Berbers show long periods of genetic isolation and appear to have diverged from surrounding populations without subsequent mixture. On the other hand, continuous gene flow from the Middle East made Egyptians genetically closer to Eurasians than to other North Africans. We show that genetic diversity of today's North Africans mostly captures patterns from migrations post Last Glacial Maximum and therefore may be insufficient to inform on the initial population of the region during the Middle Paleolithic period.This study was supported in parts by Spanish Government MCINN grant CGL2010-14944/BOS and Programa de Cooperación Interuniversitaria e Investigación Científica, Spanish Ministry of Foreign Affairs and Cooperation grants A75180/06, A/8394/07, B/018514/08, A1/040218/11.Peer Reviewe

Genetic origin, admixture, and asymmetry in maternal and paternal human lineages in Cuba

<p>Abstract</p> <p>Background</p> <p>Before the arrival of Europeans to Cuba, the island was inhabited by two Native American groups, the Tainos and the Ciboneys. Most of the present archaeological, linguistic and ancient DNA evidence indicates a South American origin for these populations. In colonial times, Cuban Native American people were replaced by European settlers and slaves from Africa. It is still unknown however, to what extent their genetic pool intermingled with and was 'diluted' by the arrival of newcomers. In order to investigate the demographic processes that gave rise to the current Cuban population, we analyzed the hypervariable region I (HVS-I) and five single nucleotide polymorphisms (SNPs) in the mitochondrial DNA (mtDNA) coding region in 245 individuals, and 40 Y-chromosome SNPs in 132 male individuals.</p> <p>Results</p> <p>The Native American contribution to present-day Cubans accounted for 33% of the maternal lineages, whereas Africa and Eurasia contributed 45% and 22% of the lineages, respectively. This Native American substrate in Cuba cannot be traced back to a single origin within the American continent, as previously suggested by ancient DNA analyses. Strikingly, no Native American lineages were found for the Y-chromosome, for which the Eurasian and African contributions were around 80% and 20%, respectively.</p> <p>Conclusion</p> <p>While the ancestral Native American substrate is still appreciable in the maternal lineages, the extensive process of population admixture in Cuba has left no trace of the paternal Native American lineages, mirroring the strong sexual bias in the admixture processes taking place during colonial times.</p

Multiplex single-nucleotide polymorphism typing of the human Y chromosome using TaqMan probes

Grupo de trabajo: The Genographic Consortium.[Background] The analysis of human Y-chromosome variation in the context of population genetics and forensics requires the genotyping of dozens to hundreds of selected single-nucleotide polymorphisms (SNPs). In the present study, we developed a 121-plex (121 SNPs in a single array) TaqMan array capable of distinguishing most haplogroups and subhaplogroups on the Y-chromosome human phylogeny in Europe.[Results] We present data from 264 samples from several European areas and ethnic groups. The array developed in this study shows >99% accuracy of assignation to the Y human phylogeny (with an average call rate of genotypes >96%).[Conclusions] We have created and evaluated a robust and accurate Y-chromosome multiplex which minimises the possible errors due to mixup when typing the same sample in several independent reactions.Peer reviewe

Genetic analysis in a familial case with high bone mineral density suggests additive effects at two loci

Osteoporosis is the most common bone disease, characterized by a low bone mineral density (BMD) and increased risk of fracture. At the other end of the BMD spectrum, some individuals present strong, fracture-resistant, bones. Both osteoporosis and high BMD are heritable and their genetic architecture encompasses polygenic inheritance of common variants and some cases of monogenic highly penetrant variants in causal genes. We have investigated the genetics of high BMD in a family segregating this trait in an apparently Mendelian dominant pattern. We searched for rare causal variants by whole-exome sequencing in three affected and three nonaffected family members. Using this approach, we have identified 38 rare coding variants present in the proband and absent in the three individuals with normal BMD. Although we have found four variants shared by the three affected members of the family, we have not been able to relate any of these to the high-BMD phenotype. In contrast, we have identified missense variants in two genes, VAV3 and ADGRE5, each shared by two of out of three affected members, whose loss of function fits with the phenotype of the family. In particular, the proband, a woman displaying the highest BMD (sum Z-score = 7), carries both variants, whereas the other two affected members carry one each. VAV3 encodes a guanine-nucleotide-exchange factor with an important role in osteoclast activation and function. Although no previous cases of VAV3 mutations have been reported in humans, Vav3 knockout (KO) mice display dense bones, similarly to the high-BMD phenotype present in our family. The ADGRE5 gene encodes an adhesion G protein-coupled receptor expressed in osteoclasts whose KO mouse displays increased trabecular bone volume. Combined, these mouse and human data highlight VAV3 and ADGRE5 as novel putative high-BMD genes with additive effects, and potential therapeutic targets for osteoporosis. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research

Zona de transición de una línea ferroviaria situada entre una vía en balasto y una vía en placa de hormigón

Zona de transición de una línea ferroviaria situada entre una vía en balasto y una vía en placa de hormigón, que comprende: - un conjunto de traviesas de hormigón de longitud superior a las traviesas de las vías en placa de hormigón y en balasto, agrupadas en secciones de traviesas de la misma longitud, con longitud creciente desde la vía en balasto a la vía en placa de hormigón, - una lámina de amortiguación de la vibración situada en sentido transversal a la vía en placa de hormigón que se extiende al menos entre la capa de balasto de la zona de transición y la capa de hormigón de la vía en placa de hormigón, - almohadillas de apoyo bajo carril con una rigidez igual o creciente desde la vía en placa de hormigón hacia la vía en balasto, - sendos carriles adicionales internos y - sendos carriles adicionales externos.Solicitud: 201730552 (31.03.2017)Nº Pub. de Solicitud: ES2684429A1 (02.10.2018

From cheek swabs to consensus sequences : an A to Z protocol for high-throughput DNA sequencing of complete human mitochondrial genomes

Background: Next-generation DNA sequencing (NGS) technologies have made huge impacts in many fields of biological research, but especially in evolutionary biology. One area where NGS has shown potential is for high-throughput sequencing of complete mtDNA genomes (of humans and other animals). Despite the increasing use of NGS technologies and a better appreciation of their importance in answering biological questions, there remain significant obstacles to the successful implementation of NGS-based projects, especially for new users. Results: Here we present an ‘A to Z’ protocol for obtaining complete human mitochondrial (mtDNA) genomes – from DNA extraction to consensus sequence. Although designed for use on humans, this protocol could also be used to sequence small, organellar genomes from other species, and also nuclear loci. This protocol includes DNA extraction, PCR amplification, fragmentation of PCR products, barcoding of fragments, sequencing using the 454 GS FLX platform, and a complete bioinformatics pipeline (primer removal, reference-based mapping, output of coverage plots and SNP calling). Conclusions: All steps in this protocol are designed to be straightforward to implement, especially for researchers who are undertaking next-generation sequencing for the first time. The molecular steps are scalable to large numbers (hundreds) of individuals and all steps post-DNA extraction can be carried out in 96-well plate format. Also, the protocol has been assembled so that individual ‘modules’ can be swapped out to suit available resources