Biology subjects

Chaubey, G.

Publications and source records attributed to Chaubey, G..

12 recordsLinked to original sources

bioRxiv2026

Holocene North Asian gene flow and cryptic substructure in the genome history of Nilgiri tribes

The Nilgiri Hills of the Western Ghats harbour several historically isolated tribal populations whose genomic history remains incompletely resolved. Here, we present a comprehensive analysis of whole genome and complete mitochondrial data from three major Nilgiri groups i.,e, Toda, Kota, and Kurumba, in the context of a broad Eurasian reference panel. Autosomal analyses reveal previously unrecognised fine scale substructure, with both Kota and Kurumba resolving into two genetically distinct clusters (Kota1/Kota2 and Kurumba1/Kurumba2). Principal component, ADMIXTURE, and fineSTRUCTURE analyses identify Toda as the most genetically drifted Nilgiri group, whereas Kota2 exhibits elevated Austroasiatic related ancestry. qpWave analysis indicates that the five genetic clusters require at least three independent ancestry streams, while qpAdm further differentiates the groups based on Onge, Indus Periphery, and Western SteppeMLBA related ancestry. Toda shows the highest Indus Periphery related and lowest Onge related ancestry among the Nilgiri groups. A distinctive ancestry component shared by Kurumba2, Kota1, Gaud and the Sri Lankan Vedda suggests deeper ancestral connections across the southern Indian Ocean region. Mitochondrial genomes reveal strong founder effects and lineage specific patterns, including R5a2b in Toda, M3a1 in Kota, and multiple M subclades together with the rare C4a2c1 lineage in Kurumba. Notably, C4a2c1, previously understudied in South India, shows phylogenetic and ancient DNA continuity with North Asian and Siberian lineages. Bayesian dating suggests its arrival in the Indian subcontinent during the early mid Holocene (~7 ka), followed by local diversification after ~5 ka. Together, these findings reveal a complex history of long range Holocene maternal gene flow and subsequent isolation driven differentiation, providing new insights into the genomic history of South Indian tribal populations.

evolutionary biology↗

bioRxiv2026

South Asian Maternal Lineage haplogroup R30 Provides Phylogenetic Evidence of human dispersal across South Asia

South Asia is central to debates on early human dispersals, particularly the Out of Africa model and Eurasian colonization. Studies of M haplogroups have been used to support both Northern and Southern route hypotheses, but current archaeological and genetic evidence in the region remains contradictory. In the present work, we find that in addition to haplogroup M lineages, a few R lineages exhibit ancient, locally rooted variation, with R30 being one of the widespread haplogroup of R lineages across South Asia. To better understand South Asian demographic history, we investigated the phylogeographic distribution of haplogroup R30, an indigenous lineage. We used 190 complete modern and ancient sequences from diverse mainland and island populations including incorporation of 44 newly generated sequences which enabled the refinement of the R30 phylogeny and the identification of a novel basal lineage, R30c. Bayesian and {rho}-based age estimates suggest that R30 originated in the Indian subcontinent ~50 kya. Early diversification likely occurred in Northern India, giving rise to R30b (~44 kya), while R30a and R30c differentiated primarily in Southern India. Several subclades of haplogroup R30 exhibit strong signatures of founder effects, particularly among the language isolate Vedda of Sri Lanka, Uru Kurumban of Southern India, and the populations of the Lakshadweep archipelago. Bayesian skyline analyses indicate long-term demographic stability followed by rapid lineage expansion ~20 kya and more recent declines consistent with localised drift and relatively recent founder events. The presence of early-diverging R30 lineages in Thailand and Indonesia further supports long-term connections between South and Southeast Asia. Overall, archaeological and genetic evidence point towards the multiple migrations for South Asia colonizations.

evolutionary biology↗

bioRxiv2025

Proteus mirabilis entails a switch from commensal to pathogen - Genomic insights from a blaTEM-1B-harboring novel isolate from India.

BackgroundProteus mirabilis is an opportunistic pathogen that can shift from gut commensalism to causing severe urinary tract and bloodstream infections. The genomic basis of P. mirabilis transition from commensalism to severe infection is not well understood, especially in Indian clinical isolates. This study aimed to explore the genomic attributes of a prevalent P. mirabilis strain in India. MethodsWhole-genome sequencing (WGS) was performed on a clinical P. mirabilis isolate by using NGS. AMR genes and virulence factors were identified using ResFinder/CARD and VFDB, respectively. Sequence typing was performed with MLST. Protein-protein interactions and noncoding RNAs were analyzed using STRING, CytoHubba, and BAKTA. ResultsWGS confirmed the multidrug-resistant nature of the isolate, revealing a broad repertoire of AMR genes, including blaTEM-1B, conferring resistance to beta-lactam antibiotics. Several resistance determinants were co-localised with insertion sequences on a single contig, indicating a high potential for horizontal gene transfer. The virulome profile highlighted multiple fimbrial genes, hemolysins, and toxin-encoding loci, together supporting strong adhesion, biofilm formation, and host tissue damage. Comparative analysis revealed unique genomic signatures not present in reference isolates, including additional virulence determinants and mobile genetic elements. MLST profile of the isolate is closely related to ST-675 & ST-797, while virulence typing (vST-1157) indicated a novel profile distinct from reference ST-675 strains. Insilico protein-protein interaction of this isolate revealed a highly interconnected virulence network, with urease, fimbrial adhesins, and hemolysins emerging as central functional modules driving pathogenicity. In addition, a noncoding RNA was identified within the genomic context of the ure operon (Contig 10), suggesting a possible regulatory role in urease expression. PPI network analysis highlighted urease, fimbrial proteins, and hemolysins as central hubs contributing to pathogenicity. ConclusionsThis study presents the first genomic characterization of a multidrug-resistant P. mirabilis clinical isolate from India, designated as P. mirabilis strain Indica. The convergence of AMR genes, virulence factors, MGEs and a novel noncoding RNAs linked to urease expression highlights the emergence of a high-risk variant in India. These findings have significant implications for infection control and emphasize the need for genomic surveillance to guide therapeutic strategies and develop new interventions globally.

microbiology↗

bioRxiv2025

Neanderthal Introgressed COVID-19 Risk Locus 3p21.31 Under Positive Selection in East Asia via LZTFL1-Driven Ciliary Changes

The Neanderthal introgressed 3p21.31 locus has been repeatedly associated as a major host genetic determinant of severe COVID-19, particularly in European and South Asian populations. However, the evolutionary history and likely effector gene remain unclear. We investigated signatures of historical selection at this locus and the mechanism by which it might influence COVID-19 severity. Using 1000 Genomes Project data from diverse global populations, we applied various selection scans methods and integrated it with functional analysis. Multiple, independent lines of evidence indicate strong positive selection at 3p21.31 in East Asians. The region exceeds the 99.99th-percentile PBS threshold in EAS, shows extended ROH and the slowest LD decay among populations, and exhibits reduced nucleotide diversity and significantly negative Tajimas D, consistent with a selective sweep. XP-EHH identified a pronounced signal centred on LZTFL1. Marginal-tree reconstruction indicates the derived allele arose in modern humans and swept to high frequency in East Asia at a time consistent with an ancient corona or related virus-like epidemic [~]20,000-25,000 (20-25 Kya) years ago. LD and pathway analyses implicate a high-LD haplotype tagging LZTFL1 shows significant enrichment for cilium-assembly and BBSome-mediated cargo-targeting pathways likely causing subtle shifts in cilium number or beat frequency, in lung and airway epithelia, thereby profoundly affecting the mucus and pathogens clearance. Based on the Overall observation, we propose that after the Neanderthal introgression, East Asia went through pathogen pressure for [~]20-25 Kya old ancient coronavirus- or related virus epidemic leading to positive selection at 3p21.31locus. These findings underscore the complex interplay between ancient admixture and adaptive events linked to modern COVID-19 severity.

evolutionary biology↗

bioRxiv2024

A sneak peek at the high altitude adaptation of the Ladakh populations

The physiological response to high-altitude stress (for individuals living at 2,400m and above sea level) has been evident. However, recent advances in genomics have allowed us to explore the molecular genetic basis of these adaptive responses and their relationship with physiological responses. In the current study, we focused on thirteen biological parameters to understand the adaptive response to the high altitude of populations living across regions of Sakti, Korzok, Hanle, Aryan and Zanskar valleys of Ladakh and to understand the variation between and across individuals. Interestingly, we found a negative correlation between haemoglobin levels and partial oxygen pressure, thereby testifying to higher haemoglobin levels as an adaptive response in these individuals. The lipid profiles, including cholesterol, triglyceride, LDL and HDL levels, varied significantly across the five regions studied. Notably, individuals from Sakti Valley showed higher LDL (>140) and cholesterol values. These variations in health parameters and lipid profiles may be attributed to diet and altitude adaptations specific to the region. Overall, the study provides valuable insights into the adaptations of highlanders living at different altitudes in the Ladakh region. The findings can have implications for better understanding the molecular mechanism of physiological responses of humans to high-altitude environments.

evolutionary biology↗

bioRxiv2024

Northeast India: Genetic Inconsistency across Ethnicity and Geography

The genetic landscape of South Asia is intriguing. In a vast geographical region like India, mostly genes follow geography, whereas in a smaller geographical region e.g., Nepal, the genetic landscape is more akin to languages. Moreover, in neighboring regions like East and Southeast Asia, language is the major denominator of the genes. However, these are not just the two alternatives, in many geographical pockets, ethnicity plays a stronger role than either of these. Being a crossroads of South and Southeast Asia, the Himalayan region is mostly populated by people speaking the Trans-Himalayan language. Archaeological and anthropological studies suggest migration and cultural diffusion in this region with the Tibetan plateau in the North. To understand this complex pattern, we have performed a fine-grained genetic analysis of the major Mizo population and its various clans living in the Himalayan geography. We have investigated 110 individuals belonging to seven different clans of Mizo people for a hundred thousand autosomal markers. We have used various statistical methods and tested the role of ethnicity and geography in shaping the genetic landscape of the Himalayan region. In contrast to the East and Southeast Asian genetic landscape, our results suggested that the fine-scaled genetic structure of Northeast India is much more complex and a mixture of interplay between languages, ethnicity, and geography. Allelic frequency-based analyses indicated that a novel Trans-Himalayan ancestry unite all the populations of this region.

evolutionary biology↗

bioRxiv2023

Reassessing the association of VDR and its polymorphisms with tuberculosis in global populations.

BackgroundVitamin D is a hormone that regulates the calcium homeostasis of the body. Besides this classical function, it is also regarded as an important immunomodulator. Most active Vitamin D actions are mediated through the Vitamin D receptor (VDR), a transcription factor and also a member of the nuclear receptor superfamily. In this study, we explored the phylogeographic attributes of the four most well-known polymorphisms of the VDR gene namely rs7975232 (ApaI), rs731235 (TaqI), rs1544410 (BsmI), rs2228570 (FokI) and also evaluated their association with the incidence of tuberculosis in global populations. This study integrated several in-silico approaches on population databases to evaluate the pattern of distribution, linkage and selection patterns of these SNPs. ResultsThe ancestral alleles of rs7975232, rs731235, and rs1544410 are still present in over 50% frequency in modern human populations. These SNPs also have a very strong linkage disequilibrium among themselves in all population groups but no haplotype blocks are seen in South Asian populations constituting these polymorphisms. The selection results reveal a negative Tajimas D value in West and East Eurasian populations suggesting positive selection in these regions... In correlation studies, we found no association between the incidence of tuberculosis and the allele or genotype frequency of these four SNPs. ConclusionThe four SNPs of VDR behave differently in South Asian populations as compared to West and East Eurasian populations but no significant association was found with the incidence of tuberculosis in global populations.

genomics↗

bioRxiv2023

Whole Genome Sequencing and Assembly of the House Sparrow, Passer domesticus

The common house sparrow, Passer domesticus is a small bird belonging to the family Passeridae. Here, we provide high-quality whole genome sequence data along with assembly for the house sparrow. The final genome assembly was assembled using a Shovill/SPAdes/MASURCA/BUSCO workflow, consisting of contigs spanning 268193 bases and coalescing around a 922 MB sized reference genome. We employed rigorous statistical thresholds to check the coverage, as the Passer genome showed considerable similarity to Gallus gallus (chicken) and Taeniopygia guttata (Zebra finch) genomes, also providing a functional annotation. This new annotated genome assembly will be a valuable resource as a reference for comparative and population genomic analyses of passerine, avian, and vertebrate evolution. SignificanceAvian evolution has been of great interest in the context of extinction. Annotating the genomes such as passerines would be of significant interest as we could understand the behavior/foraging traits and further explore their evolutionary landscape. In this work, we provide a full genome sequence of Indian house sparrow, viz. Passer domesticus which will serve as a useful resource in understanding the adaptability, evolution, geography, allee effects and circadian rhythms.

evolutionary biology↗

bioRxiv2021

Genetic association of TMPRSS2 rs2070788 polymorphism with COVID-19 Case Fatality Rate among Indian populations

SARS-CoV2, the causative agent for COVID-19, an ongoing pandemic, engages the ACE2 receptor to enter the host cell through S protein priming by a serine protease, TMPRSS2. Variation in the TMPRSS2 gene may account for the difference in population disease susceptibility. The haplotype-based genetic sharing and structure of TMPRSS2 among global populations have not been studied so far. Therefore, in the present work, we used this approach with a focus on South Asia to study the haplotypes and their sharing among various populations worldwide. We have used next-generation sequencing data of 393 individuals and analysed the TMPRSS2 gene. Our analysis of genetic relatedness for this gene showed a closer affinity of South Asians with the West Eurasian populations therefore, host disease susceptibility and severity particularly in the context of TMPRSS2 will be more akin to West Eurasian instead of East Eurasian. This is in contrast to our prior study on ACE2 gene which shows South Asian haplotypes have a strong affinity towards West Eurasians. Thus ACE2 and TMPRSS2 have an antagonistic genetic relatedness among South Asians. We have also tested the SNPs frequencies of this gene among various Indian state populations with respect to the case fatality rate. Interestingly, we found a significant positive association between the rs2070788 SNP (G Allele) and the case fatality rate in India. It has been shown that the GG genotype of rs2070788 allele tends to have a higher expression of TMPRSS2 in the lung compared to the AG and AA genotypes, thus it might play a vital part in determining differential disease vulnerability. We trust that this information will be useful in underscoring the role of the TMPRSS2 variant in COVID-19 susceptibility and using it as a biomarker may help to predict populations at risk.

genetics↗

bioRxiv2019

Counting the paternal founders of Austroasiatic speakers associated with the language dispersal in South Asia

The phylogenetic analysis of Y chromosomal haplogroup O2a-M95 was crucial to determine the nested structure of South Asian branches within the larger tree, predominantly present in East and Southeast Asia. However, it had previously been unclear how many founders brought the haplogroup O2a-M95 to South Asia. On the basis of the updated Y chromosomal tree for haplogroup O2a-M95, we analysed 1,437 male samples from South Asia for various downstream markers, carefully selected from the extant phylogenetic tree. With this increased resolution, we were able to identify at least three founders downstream to haplogroup O2a-M95 who are likely to have been associated with the dispersal of Austroasiatic languages to South Asia. The fourth founder was exclusively present amongst Tibeto-Burman speakers of Manipur and Bangladesh. In sum, our new results suggest the arrival of Austroasiatic languages in South Asia during last five thousand years.

evolutionary biology↗

bioRxiv2018

The genetic legacy of continental scale admixture in Indian Austroasiatic speakers

Surrounded by speakers of Indo-European, Dravidian and Tibeto-Burman languages, around 11 million Munda (a branch of Austroasiatic language family) speakers live in the densely populated and genetically diverse South Asia. Their genetic makeup holds components characteristic of South Asians as well as Southeast Asians. The admixture time between these components has been previously estimated on the basis of archaeology, linguistics and uniparental markers. Using genome-wide genotype data of 102 Munda speakers and contextual data from South and Southeast Asia, we retrieved admixture dates between 2000 - 3800 years ago for different populations of Munda. The best modern proxies for the source populations for the admixture with proportions 0.78/0.22 are Lao people from Laos and Dravidian speakers from Kerala in India, while the South Asian population(s), with whom the incoming Southeast Asians intermixed, had a smaller proportion of West Eurasian component than contemporary proxies. Somewhat surprisingly Malaysian Peninsular tribes rather than the geographically closer Austroasiatic languages speakers like Vietnamese and Cambodians show highest sharing of IBD segments with the Munda. In addition, we affirmed that the grouping of the Munda speakers into North and South Munda based on linguistics is in concordance with genome-wide data.

genetics↗

bioRxiv2017

Like Sugar in Milk: Reconstructing the genetic history of the Parsi population

BackgroundThe Parsis, one of the smallest religious community in the world, reside in South Asia. Previous genetic studies on them, although based on low resolution markers, reported both Iranian and Indian ancestries. To understand the population structure and demographic history of this group in more detail, we analyzed Indian and Pakistani Parsi populations using high-resolution autosomal and uniparental (Y-chromosomal and mitochondrial DNA) markers. Additionally, we also assayed 108 mitochondrial DNA markers among 21 ancient Parsi DNA samples excavated from Sanjan, in present day Gujarat, the place of their original settlement in India.\n\nResultsOur extensive analyses indicated that among present-day populations, the Parsis are genetically closest to Middle Eastern (Iranian and the Caucasus) populations rather than their South Asian neighbors. They also share the highest number of haplotypes with present-day Iranians and we estimate that the admixture of the Parsis with Indian populations occurred [~]1,200 years ago. Enriched homozygosity in the Parsi reflects their recent isolation and inbreeding. We also observed 48% South-Asian-specific mitochondrial lineages among the ancient samples, which might have resulted from the assimilation of local females during the initial settlement.\n\nConclusionsWe show that the Parsis are genetically closest to the Neolithic Iranians, followed by present-day Middle Eastern populations rather than those in South Asia and provide evidence of sex-specific admixture from South Asians to the Parsis. Our results are consistent with the historically-recorded migration of the Parsi populations to South Asia in the 7thcentury and in agreement with their assimilation into the Indian sub-continents population and cultural milieu \"like sugar in milk\". Moreover, in a wider context our results suggest a major demographic transition in West Asia due to Islamic-conquest.

evolutionary biology↗