Project description:The genome of two local sheep breeds from the Basque Country, Sasi Ardi and Latxa, have been resequenced and scanned searching for selective sweeps related with natural and artificial selection.
Project description:To investigate the genetic basis of preeclampsia and its relationship to altitude, we characterized genetic diversity in a cohort of Andean families (N=883) from Puno, Peru, a high altitude city above 3,500 m. Our study collected genetic samples and medical records from case-control trios and duos, thus allowing for measurement of maternal, paternal and fetal genetic factors on preeclampsia risk. We generated high-density genotype data at over 400,000 positions across the genome, and used these data to determine ancestry patterns and map associations between genetic variants and preeclampsia phenotype. We also generated capture sequencing data from a subset of the study cohort focusing on genomic regions surrounding our top candidate hits.
Project description:During the first weeks of human immunodeficiency virus-1 (HIV-1) infection, cytotoxic T-lymphocytes (CTLs) select for multiple escape mutations in the infecting HIV population. In recent years, methods that use escape mutation data to estimate rates of HIV escape have been developed, thereby providing a quantitative framework for exploring HIV escape from CTL response. Current methods for escape-rate inference focus on a specific HIV mutant selected by a single CTL response. However, recent studies have shown that during the first weeks of infection, CTL responses occur at one to three epitopes and HIV escape occurs through complex mutation pathways. Consequently, HIV escape from CTL response forms a complex, selective sweep that is difficult to analyze. In this work, we develop a model of initial infection, based on the well-known standard model, that allows for a description of multi-epitope response and the complex mutation pathways of HIV escape. Under this model, we develop Bayesian and hypothesis-test inference methods that allow us to analyze and estimate HIV escape rates. The methods are applied to two HIV patient data sets, concretely demonstrating the utility of our approach.
Project description:Understanding molecular mechanism associated with high altitude exposure during acclimatization/adaptation/maladaptation. Data reveals specific components of the complex molecular circuitry underlying high altitude pulmonary edema. Individualized outcome prediction were constructed through expression profiling of 39400 genes in sea level sojourners who were acclimatized to high altitude and grouped as controls (n=14), high altitude natives (n=14) and individuals who developed high altitude pulmonary edema within 48-72 hours after air induction to high altitude (n=17).
Project description:Over the last several hundred years, donkeys have adapted to high-altitude conditions on the Tibetan Plateau. Interestingly, the kiang, a closely related equid species, also inhabits this region. Previous reports have demonstrated the importance of specific genes and adaptive introgression in divergent lineages for adaptation to hypoxic conditions on the Tibetan Plateau. Here, we assessed whether donkeys and kiangs adapted to the Tibetan Plateau via the same or different biological pathways and whether adaptive introgression has occurred. We assembled a de novo genome from a kiang individual and analyzed the genomes of five kiangs and 93 donkeys (including 24 from the Tibetan Plateau). Our analyses suggested the existence of a strong hard selective sweep at the EPAS1 locus in kiangs. In Tibetan donkeys, however, another gene, i.e., EGLN1, was likely involved in their adaptation to high altitude. In addition, admixture analysis found no evidence for interspecific gene flow between kiangs and Tibetan donkeys. Our findings indicate that despite the short evolutionary time scale since the arrival of donkeys on the Tibetan Plateau, as well as the existence of a closely related species already adapted to hypoxia, Tibetan donkeys did not acquire adaptation via admixture but instead evolved adaptations via a different biological pathway.
Project description:Genetic variations of the TCF7L2 gene are associated with the development of Type 2 diabetes (T2D). The associated mutations have demonstrated an adaptive role in some human populations, but no studies have determined the impact of evolutionary forces on genetic diversity in indigenous populations from Mexico. Here, we sequenced and analyzed the variation of the TCF7L2 gene in three Amerindian populations and compared the results with whole-exon-sequencing of Mestizo populations from Sigma and the 1000 Genomes Project to assess the roles of selection and recombination in diversity.The diversity in the indigenous populations was biased to intronic regions. Most of the variation was low frequency. Only mutations rs77961654 and rs61724286 were located on exon 15. We did not observe variation in intronic region 4-6 in any of the three indigenous populations. In addition, we identified peaks of selective sweeps in the mestizo samples from the Sigma Project within this region. By replicating the analysis of association with T2D between case-controls from the Sigma Project, we determined that T2D was most highly associated with the rs7903146 risk allele and to a lesser extent with the other six variants. All associated markers were located in intronic region 4-6, and their r(2) values of linkage disequilibrium were significantly higher in the Mexican population than in Africans from the 1000 Genomes Project. We observed reticulations in both the haplotypes network analysis from seven marker associates and the neighborNet tree based on 6061 markers in the TCF7L2 gene identified from all samples of the 1000 Genomes Project. Finally, we identified two recombination hotspots in the upstream region and 3' end of the TCF7L2 gene.The lack of diversity in intronic region 4-6 in Indigenous populations could be an effect of selective sweeps generated by the selection of neighboring rare variants at T2D-associated mutations. The survivors' variants make the intronic region 4-6 the area of the greatest population differentiation within the TCF7L2 gene. The abundance of selective peak sweeps in the downstream region of the TCF7L2 gene suggests that the TCF7L2 gene is part of a region that is in constant recombination between populations.
Project description:Purpose: High-altitude adaptive evolution of transcription, and the convergence and divergence of transcriptional alteration across species in response to high-altitude environments, is an important topic of broad interest to the general biology community. Our study aims to answer this important biological question. Methods: We generated deep transcriptome data of high- and low- altitude populations across four species: chicken, pig, goat and sheep, as well as high-altitude yak and low-altitude cattle, from six tissues (heart, kidney, liver, lung, skeletal muscle and spleen). Results: Here we provide a comprehensive comparative transcriptome landscape of expression and alternative splicing variation between low- and high-altitude populations across multiple species for distinct tissues. Conclusions: Our data serves a valuable resource for further study on adaptive transcription evolution and identification of candidate adaptive genes.
Project description:Altitude acclimatization is the physiological process to restore oxygen delivery to the tissues and promote the oxygen application under high altitude hypoxia. High altitude illness could happen in individuals who did not get acclimatization. Unraveling the molecular underpinnings of altitude acclimatization would help people to understand the beneficial response of body to high altitude hypoxia and disturbed biological process in un-acclimatized individuals. Here, we measured physiological adjustments and circulating microRNAs (cmiRNAs) profiles of individuals exposed to high altitude to explore the altitude acclimatization in humans.