Biology subjects

Islam, M. T.

Publications and source records attributed to Islam, M. T..

32 records · Page 2Linked to original sources

bioRxiv2023

Molecular Investigation of TSHR gene in Bangladeshi Congenital Hypothyroid patients

The disorder of thyroid gland development or thyroid dysgenesis (TH) accounts for 80-85% cases of congenital hypothyroidism (CH). Hence, the understanding of molecular etiology of TH is prerequisite. Mutations in TSHR gene is mostly associated with thyroid dysgenesis, prevent or disrupt normal development of the gland. The current study detects two nonsynonymous mutations (p.Ser508Leu, p.Asp727Glu) in transmembrane (TM)-region (Exon 10) of TSHR gene in 21 patients with dysgenesis by sequencing-based analysis. Later, transmembrane (TM)-region of TSHR protein is modelled by homology modeling. Transmembrane (TM)-region of TSHR protein is targeted by small molecules thyrogenic drugs, MS437 and MS438 to perceive the effect of mutations. The damaging effect in drug-protein complexes of mutants were envisaged by molecular docking and interactions. The binding affinity of wild type protein was much higher than the mutant cases for both of the ligands (MS437 and MS438). Molecular dynamics simulates dynamic behavior of wild type and mutant complexes. MS437-TSHR368-764MT2 and MS438-TSHR368-764MT1 show stable conformations in biological environments. Finally, PCA reveals structural and energy profile discrepancies. TSHR368-764MT1 exhibits much variations than TSHR368-764WT and TSHR368-764MT2, emphasizing more damaging pattern in TSHR368-764MT1. The study might be helpful to understand molecular etiology of thyroid dysgenesis (TH) exploring the mutational impact on TSHR protein to the interaction with agonists.

genetics↗

bioRxiv2022

Vibrio tarriae sp. nov., a novel member of the Cholerae clade isolated from across the United States

A number of bacteria with close resemblance to Vibrio cholerae has been isolated over the years by the Centers for Disease Control and Prevention (CDC), which could not be assigned a proper taxonomic designation based on preliminary identification methods. Nine such isolates have been found to share 16S rRNA gene identity exceeding 99% with V. cholerae, yet DNA-DNA hybridization (60.4-62.1%) and average nucleotide identity values (94.4-95.1%) were below the species cut-off, indicating a potentially novel species. Phylogenetic analysis of core genomes places this group of isolates in a monophyletic clade, within the "Cholerae clade," but distinct from any other species. Extensive phenotypic characterization reveals unique biochemical properties that distinguish this novel species from V. cholerae. Comparative genomic analysis reveals a unique set of siderophore genes, suggesting that iron acquisition strategies could be vital for the divergence of the novel species from a common ancestor with V. cholerae. Based on genetic, phylogenetic, and phenotypic differences observed, we propose these isolates represent a novel species of the genus Vibrio, for which the name Vibrio tarriae sp. nov. is proposed. Strain 2521-89 (= DSM 112461 = CCUG 75318), isolated from lake water, is the type strain. Author NotesThe GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain 2521-89 is MW773202.1. The genome sequences (genome assemblies) of strains 2521-89, 2523-88, 2015V-1076, 2016V-1018, 2016V-1062, 2017V-1038, 2017V-1070 and 2017V-1124 are deposited under the accession number NZ_CP022353.1, QKKG01000001.1, QKKH00000000.1, QKKI00000000.1, QKKJ00000000.1, QKKK00000000.1, QKKM00000000.1, and QKKN00000000.1, respectively. All the whole genome sequences are deposited under bioproject ID: PRJNA391152.

microbiology↗

bioRxiv2022

SERM: a self-consistent deep learning solution forrapid and accurate gene expression recovery

Single cell RNA sequencing (scRNA-seq) is a promising technique to determine the states of individual cells and classify novel cell subtypes. Computationally, the processing of scRNA-seq data presents a daunting challenge because of the noisy nature and humongous size and dimensionality of the data. Compromised solution by omitting the genes with low expression is commonly taken in current scRNA-seq analysis, which leads to inaccurate gene counts. In this paper, we introduce a broadly applicable data-driven gene expression recovery framework, referred to as the self-consistent expression recovery machine (SERM), to impute the missing gene expression. Using deep learning, SERM first learns from a subset of the noisy gene expression data to estimate the underlying data distribution. SERM then recovers the overall gene expression data by imposing a self-consistency on the gene expression matrix, thus ensuring that the expression levels are similarly distributed in different parts of the matrix. We show that SERM significantly improves the accuracy of gene imputation with at least 100-fold increase in computational efficiency in comparison to the state-of-the-art techniques. Thus SERM promises to provide an urgently needed computational solution for rapid and accurate recovery of big genomic expression data. SERM is available as a web-based computational tool (https://www.analyxus.com/compute/serm) and its source codes can be found in https://github.com/xinglab-ai/self-consistent-expression-recovery-machine.

bioinformatics↗

bioRxiv2021

Rapid and robust directed differentiation of mouse epiblast stem cells into definitive endoderm and forebrain organoids

Directed differentiation of pluripotent stem cells (PSCs) is a powerful model system for deconstructing embryonic development. Although mice are the most advanced mammalian model system for genetic studies of embryonic development, state-of-the-art protocols for directed differentiation of mouse PSCs into defined lineages require additional steps and generate target cell types with lower purity than analogous protocols for human PSCs, limiting their application as models for mechanistic studies of development. Here, we examine the potential of mouse epiblast stem cells (EpiSCs) cultured in media containing Wnt pathway inhibitors as a starting point for directed differentiation. As a proof-of-concept, we focused our efforts on two specific cell/tissue types that have proven difficult to generate efficiently and reproducibly from mouse embryonic stem cells: definitive endoderm and neural organoids. We present new protocols for rapid generation of nearly pure definitive endoderm and forebrain-patterned neural organoids that model the development of prethalamic and hippocampal neurons. These differentiation models present new possibilities for combining mouse genetic tools with in vitro differentiation to characterize molecular and cellular mechanisms of embryonic development. SUMMARY STATEMENTNew optimized protocols for directed differentiation of mouse epiblast stem cells into definitive endoderm and forebrain-patterned organoids.

developmental biology↗

bioRxiv2021

Vibrio cholerae El Tor strains linked to global cholera are homogeneous by pulsed-field gel electrophoresis

Vibrio cholerae O1 El Tor, causative agent of the ongoing seventh cholera pandemic, is native to the aquatic environment of the Ganges Delta, Bay of Bengal (GDBB). Recent studies traced pandemic strains to the GDBB and proposed global spread of cholera had occurred via intercontinental transmission. In the research presented here, NotI-digested genomic DNA extracted from V. cholerae O1 clinical and environmental strains isolated in Bangladesh during 2004 - 2014 was analyzed by pulsed-field gel electrophoresis (PFGE). Results of cluster analysis showed 94.67% of the V. cholerae isolates belonged to clade A and included the majority of clinical isolates of spatio-temporal origin and representing different cholera endemic foci. The rest of the strains were estuarine, all environmental isolates from Mathbaria, Bangladesh, and occurred as singletons, clustered in clades B and C, or in the small clades D and E. Cluster analysis of the Bangladeshi strains and including 157 El Tor strains from thirteen countries in Asia, Africa, and the Americas revealed 85% of the total set of isolates belonged to clade A, indicating all were related, yet did not form an homogeneous cluster. Overall, 15% of the global strains comprised multiple small clades or segregated as singletons. Three sub-clades could be discerned within the major clade A, reflecting distinct lineages of V. cholerae El Tor associated with cholera in Asia, Africa, and the Americas. The presence in Asia and the Americas of non-pandemic V. cholerae El Tor populations differing by PFGE and from strains associated with cholera globally suggests different ecotypes are resident in distant geographies. Author SummaryCholera is a major health threat, especially in the Ganges Delta, Bay of Bengal (GDBB). Vibrio cholerae, causative agent of cholera, is native to the GDBB aquatic environment. Recent genomic studies suggest GDBB is the cholera hotspot where the disease spreads globally via human activity. Pulsed-field gel electrophoresis (PFGE) of NotI-digested genomic DNA from V. cholerae El Tor endemic cholera strains was done, including Bangladesh aquatic environment and clinical strains from distant geographical regions representing three cholera-prone continents. Results showed the majority of pandemic strains belonged to a major cluster, suggesting clonal relatedness. Ecotypes were detected, indicating geographically specific lineages. It is concluded that epidemic strains in Bangladesh and thirteen countries of Asia, Africa, and the Americas are geographically adapted, with independent evolution of the bacterium in respective geographical regions.

molecular biology↗

bioRxiv2021

Population analysis of Vibrio cholerae in aquatic reservoirs reveals a novel sister species (Vibrio paracholerae sp. nov.) with a history of association with human infections

Most efforts to understand the biology of Vibrio cholerae have focused on a single group, the pandemic-generating lineage harbouring the strains responsible for all known cholera pandemics. Consequently, little is known about the diversity of this species in its native aquatic environment. To understand the differences in the V. cholerae populations inhabiting in regions with varying history of cholera cases and how that might influence the abundance of pandemic strains, a comparative analysis of population composition was performed. Little overlap was found in lineage compositions between those in Dhaka (cholera endemic) located in the Ganges delta, and of Falmouth (no known history of cholera), a small coastal town on the US East Coast. The most striking difference was the presence of a group of related lineages at high abundance in Dhaka which was completely absent from Falmouth. Phylogenomic analysis revealed that these lineages form a cluster at the base of the phylogeny of V. cholerae species, sufficiently differentiated genetically and phenotypically to form a novel species. Strains from this species have been anecdotally isolated from around the world and were isolated as early as 1916 from a British soldier in Egypt suffering from choleraic diarrhoea. In 1935 Gardner and Venkatraman unofficially referred to a member of this group as Vibrio paracholerae. In recognition of this earlier designation, we propose the name Vibrio paracholerae, sp. nov. for this bacterium. Genomic analysis suggests a link with human populations for this novel species and substantial interaction with its better-known sister species. ImportanceCholera continues to remain a major public health threat around the globe. Understanding the ecology, evolution and environmental adaptation of the causative agent Vibrio cholerae and tracking the emergence of novel lineages with pathogenic potential are essential to combat the problem. In this study, we investigated the population dynamics of Vibrio cholerae in an inland locality which is known as endemic for cholera and compared with that of a cholera free coastal location. We found the consistent presence of the pandemic generating V. cholerae in cholera-endemic Dhaka and an exclusive presence of a lineage phylogenetically distinct from other V. cholerae. Our study suggests that this lineage represents a novel species having pathogenic potential and a human link to its environmental abundance. The possible association with human population, co-existence and interaction with toxigenic V. cholerae in the natural environment make this potential human pathogen an important subject for future studies.

microbiology↗

bioRxiv2020

Sonic hedgehog signaling directs patterned cell remodeling during cranial neural tube closure

Neural tube closure defects are a major cause of infant mortality, with exencephaly accounting for nearly one-third of cases. However, the mechanisms of cranial neural tube closure are not well understood. Here we show that this process involves a tissue-wide pattern of apical constriction controlled by Sonic hedgehog (Shh) signaling. Midline cells in the mouse midbrain neuroepithelium are short with large apical surfaces, whereas lateral cells are taller and undergo synchronous apical constriction, driving neural fold elevation. Embryos lacking the Shh effector Gli2 fail to produce appropriate midline cell architecture, whereas embryos with expanded Shh signaling, including the IFT-A complex mutants Ift122 and Ttc21b and embryos expressing activated Smoothened, display apical constriction defects in lateral cells. Disruption of lateral, but not midline, cell remodeling results in exencephaly. These results reveal a morphogenetic program of patterned apical constriction governed by Shh signaling that generates structural changes in the developing mammalian brain.

developmental biology↗

bioRxiv2020

Association of poor virus specific immunoglobulin G antibodyresponses with higher viral load is seen in Bangladeshi pregnantwomen having acute Hepatitis E Genotype 1 infection

Although Hepatitis E viral illness is usually self-limiting, higher rates of morbidity and mortality are frequently observed during pregnancy in South Asian countries including Bangladesh. Of the four common variants, hepatitis E virus genotype 1 is mainly prevalent in South Asian countries. Pregnant women usually suffer from a state of immunosuppression. It is yet to be known whether virus specific immunoglobulin G (IgG) immune responses have any association with the vulnerability of pregnant women to acute hepatitis with E virus. The study aimed to compare the viral load and IgG responses of hepatitis E-infected pregnant women with that of non-pregnant women with same infection. Real Time -quantitative reverse transcription Polymerase Chain Reaction and Sanger sequencing were performed to determine the viral load and genotype, respectively, whereas Enzyme Linked Immunosorbent Assay method was used to determine hepatitis E virus specific serum IgG antibody index along with IgG avidity index. Although significant negative correlations were observed between log viral copy number and log IgG antibody index in the late acute phases of jaundice for both pregnant (r= -0.7971, p=0.0002) and non-pregnant women (r= -0.9117, p=0.0002), serum log viral copy number of pregnant women was significantly higher than that of the non-pregnant counterpart (p=0.0196) in the late acute stage of jaundice. In addition, log hepatitis E virus IgG antibody index of pregnant women was significantly lower than the non-pregnant women in the late phase of jaundice induced by hepatitis E virus (p=0.0303). Moreover, pregnant women with acute hepatitis E had higher cross-reactive IgG than in the non-pregnant women (p=0.0017). All the patients got infected with hepatitis E virus were in Genotype 1 variety. The study demonstrates that virus-specific poor IgG responses might be responsible for vulnerability of pregnant women to acute hepatitis with hepatitis E virus. Author SummaryAcute hepatitis caused by hepatitis E virus (HEV) Genotype 1 is a public health problem in Asian countries and especially it poses a potential health threat to pregnant women causing 19% to 25% mortality, particularly in South Asian countries including Bangladesh. The study aimed to explore whether HEV IgG immune responses were compromised during pregnancy, which might contribute to higher viral load and disease severity. Accordingly, pregnant and non-pregnant women with acute hepatitis (clinically presented with nausea, loss of appetite and /or jaundice) were enrolled from different tertiary care hospitals in Dhaka city. All these patients were screened and hepatitis E were differentiated from other hepatitis (caused by A, B, C) using Enzyme Linked Immunosorbent Assay (ELISA) methods. HEV IgG antibody/avidity indices and viral loads were measured using ELISA and real time quantitative polymerase chain reaction (RT-qPCR), respectively. The study showed that pregnant women with acute hepatitis E had lower IgG indices with higher viral load than their non-pregnant counterpart. Overall, the study revealed that virus-specific poor IgG responses might render pregnant women vulnerable to acute hepatitis E of varying degree of severity which might be associated with higher viral load.

immunology↗

bioRxiv2020

Situation of antibiotic resistance in Bangladesh and its association with resistance genes for horizontal transfer

The study investigated the spectrum of antibiotic resistance and the associated genes for aminoglycoside, macrolide and ESBL class of antibiotics using clinical isolates. A total of 430 preserved bacterial strains (Acinetobacter baumannii, n= 20; Pseudomonas aeruginosa, n= 26; Klebsiella pneumoniae, n= 42; E.coli, n= 85; Staphylococcus aureus, n= 84; Salmonella Typhi, n= 82; Enterococcus spp., n= 27; Streptococcus pneumoniae, n= 36 and CNS, n= 28) were examined. The strains were isolated from patients admitted to various tertiary hospitals of Dhaka city between 2015 and 2019 with either acute respiratory infections, wound infections, typhoid fever or diarrhea. The isolates were reconfirmed by appropriate microbiological and biochemical methods. Antimicrobial susceptibility tests were done using Kirby-Bauer disk diffusion approach. PCR amplification using resistance gene-specific primers for aminoglycoside, macrolide and ESBL class of antibiotics was done and the amplified products were confirmed by Sanger sequencing. Of the total isolates, 53% came out as MDR with 96.6% of E. coli and 90% of Staphylococcus aureus. There was a year-wise gradual increase of MDR isolates from 2015-2018 and by 2019 the increase in MDR isolates became almost 2-fold compared to 2015. Among the five ESBL genes investigated, CTXM-1 came out as the most prevalent (63%) followed by NDM-1 (22%) and E. coli isolates were the predominant reservoir of these genes. ErmB (55%) was the most frequently detected macrolide resistance gene, whereas aac(6)-Ib (35.44%) was the most prevalent aminoglycoside resistance gene and these genes were most prevalent in E. coli and P. aeruginosa isolates, respectively. CTXM-1 and ErmB (16.66%) were the most frequent partners of coexistence followed by CTXM-1 and aac(3)-II.

microbiology↗

bioRxiv2020

A Vibrio Cholerae Core Genome Multilocus Sequence Typing Scheme to Facilitate the Epidemiological Study of Cholera

Core genome multilocus sequence typing (cgMLST) has gained popularity in recent years in epidemiological research and subspecies level classification. cgMLST retains the intuitive nature of traditional MLST but offers much greater resolution by utilizing significantly larger portions of the genome. Here, we introduce a cgMLST scheme for Vibrio cholerae, a bacterium abundant in marine and freshwater environments and the etiologic agent of cholera. A set of 2,443 core genes ubiquitous in V. cholerae were used to analyze a comprehensive dataset of 1,262 clinical and environmental strains collected from 52 countries, including 65 newly sequenced genomes in this study. We established a sublineage threshold based on 133 allelic differences that creates clusters nearly identical to traditional MLST types, providing backwards compatibility to new cgMLST classifications. We also defined an outbreak threshold based on seven allelic differences that is capable of identifying strains from the same outbreak and closely related isolates which could give clues on outbreak origin. Using cgMLST, we confirmed the South Asian origin of modern epidemics and identified clustering affinity among sublineages of environmental isolates from the same geographic origin. Advantages of this method are highlighted by direct comparison with existing classification methods, such as MLST and single nucleotide polymorphism-based methods. cgMLST outperforms all existing methods in terms of resolution, standardization, and ease-of-use. We anticipate this scheme will serve as a basis for a universally applicable and standardized classification system for V. cholerae research and epidemiological surveillance in the future. This cgMLST scheme is publicly available on PubMLST (https://pubmlst.org/vcholerae/). IMPORTANCEToxigenic Vibrio cholerae of the O1 and O139 serogroups are the causative agent of cholera, an acute diarrheal disease that plagued the world for centuries, if not millennia. Here, we introduce a core genome multilocus sequence typing (cgMLST) scheme for V. cholerae. Using cgMLST, we established an outbreak threshold that can efficiently identify outbreak related strains and potential sources of introduction. We also defined a sublineage threshold that is similar to traditional MLST sequence type which will provide context to this new typing method by relating it to previous MLST results. cgMLST outperforms all existing methods in terms of resolution, standardization, and ease-of-use, making this scheme the most suitable method for V. cholerae typing and surveillance worldwide.

microbiology↗

bioRxiv2019

Simultaneous quantification of Vibrio metoecus and Vibrio cholerae with its O1 serogroup and toxigenic subpopulations in environmental reservoirs

Vibrio metoecus is a recently described and little studied causative agent of opportunistic infections in humans, often coexisting with V. cholerae in aquatic environments. However, the relative abundance of V. metoecus with V. cholerae and their population dynamics in aquatic reservoirs is still unknown. We developed a multiplex qPCR assay with a limit of detection of three copies per reaction to simultaneously quantify total V. metoecus and V. cholerae abundance, as well as the toxigenic and O1 serogroup subpopulations of V. cholerae from environmental samples. Four different genes were targeted as specific markers for individual Vibrio species or subpopulations; viuB, a gene encoding a vibriobactin utilization protein, was used to quantify the total V. cholerae population. The cholera toxin gene ctxA provided an estimation of toxigenic V. cholerae abundance, while the rfbO1 gene specifically detected and quantified V. cholerae belonging to the O1 serogroup, which includes almost all lineages of the species responsible for the majority of past and ongoing cholera pandemics. To measure V. metoecus abundance, the gene mcp, encoding methyl accepting chemotaxis protein, was used. Marker specificity was confirmed by testing several isolates of V. cholerae and V. metoecus alongside negative controls of isolates within and outside of the Vibrio genus. Analysis of environmental water samples collected from four different geographic locations including cholera-endemic (Dhaka, Kuakata and Mathbaria in Bangladesh) and non-endemic (Oyster Pond in Falmouth, Massachusetts, USA) regions showed that V. metoecus was only present in the USA site, recurring seasonally. Within the coastal USA site, the non-toxigenic O1 serogroup represented up to [~]18% of the total V. cholerae population. V. cholerae toxigenic O1 serogroup was absent or present in low abundance in coastal Bangladesh (Kuakata and Mathbaria) but constituted a relatively high proportion of the total V. cholerae population sustained throughout the year in inland Bangladesh (Dhaka). A preference for host/particle attachment was observed, as the majority of cells from both Vibrio species (>90%) were identified in the largest water size fraction sampled, composed of particles or organisms >63 m and their attached bacteria. This is the first study to apply a culture-independent method to quantify V. cholerae or V. metoecus directly in environmental reservoirs of areas endemic and non-endemic for cholera on significant temporal and spatial scales.\n\nSIGNIFICANCECholera is a life-threatening disease that requires immediate intervention; it is of prime importance to have fast, accurate and sensitive means to detect V. cholerae. Consistent environmental monitoring of the abundance of V. cholerae along with its toxigenic and O1 serogroup subpopulations could facilitate the determination of the actual distribution of this organism in aquatic reservoirs and thus help to predict an outbreak before it strikes. The lack of substantial temporal and spatial environmental sampling, along with specific quantitative measures, has made this goal elusive so far. The same is true for V. metoecus, a close relative of V. cholerae which has been associated with several clinical infections and could likely pose an emerging threat, readily exchanging genetic material with its more famous relative.

microbiology↗

bioRxiv2019

PHYSIOLOGICAL GROWTH INDICES OF MAIZE (Zea mays L.) GENOTYPES IN SYLHET

Maize (Zea mays L.) is an important food and feed crop in Bangladesh as well as in the world. But its cultivation is limited in the soils of Sylhet, Bangladesh. To study the physiological growth indices of maize genotypes an experiment was carried out at the experimental field of Sylhet Agricultural University (SAU), Bangladesh during December 2014 to May 2015. The maize genotypes as the experimental materials were ZM 0001, ZM 0002, ZM 0003, ZM 0004, ZM 0005, ZM 0006 ZM 0007 and BARI Maize 6. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Seeds were sown on 26 December 2014. Proper cultural management practices were followed as and when necessary during the growing period of the crop. Data were recorded on dry matter partitioning, different growth rate parameters and dry matter production of different plant parts at 30 days interval. The results indicated significant variations in almost all of the growth indices. Dry matter accumulation continued to increase from seedling to harvesting. The highest root dry matter was found in ZM 0007 (36.03 g) whereas the highest shoot and leaf dry matter was found in BARI Maize 6 (254.6 and 45.99 g, respectively) at harvest. The highest total dry matter (TDM) was produced in BARI Maize 6 at harvest (287.5 g) and AGR and CGR value was also highest in BARI Maize 6 (5.686 g day-1 and 45.48 g m-2 day-1) but at 60-90 days after germination (DAG). The highest RGR value was in ZM 0001 at seedling stage (114.1 mg g-1 day-1). A zigzag pattern graph was observed in all genotypes for RSR, RWR and SWR at different growth stages but a declining trend from seedling to harvesting was observed for LWR. Correlation between the growth rate parameters and kernel yield showed that shoot, leaf, total dry weight, AGR, CGR, RGR and SWR had significant positive correlation with yield.

plant biology↗

bioRxiv2018

The MoT3 assay does not distinguish between Magnaporthe oryzae wheat and rice blast isolates from Bangladesh

The blast fungus Magnaporthe oryzae is comprised of lineages that exhibit varying degrees of specificity on about 50 grass hosts, including rice, wheat and barley. Reliable diagnostic tools are essential given that the pathogen has a propensity to jump to new hosts and spread to new geographic regions. Of particular concern is wheat blast, which has suddenly appeared in Bangladesh in 2016 before spreading to neighboring India. In these Asian countries, wheat blast strains are now co-occurring with the destructive rice blast pathogen raising the possibility of genetic exchange between these destructive pathogens. We assessed the recently described MoT3 diagnostic assay and found that it did not distinguish between wheat and rice blast isolates from Bangladesh. The assay is based on primers matching the WB12 sequence corresponding to a fragment of the M. oryzae MGG_02337 gene annotated as a short chain dehydrogenase. These primers could not reliably distinguish between wheat and rice blast isolates from Bangladesh based on DNA amplification experiments performed in separate laboratories in Bangladesh and in the UK. In addition, comparative genomics of the WB12 sequence revealed a complex underlying genetic structure with related sequences across M. oryzae strains and in both rice and wheat blast isolates. We, therefore, caution against the indiscriminate use of this assay to identify wheat blast.

plant biology↗

bioRxiv2016

Co-occurring eQTLs and mQTLs: detecting shared causal variants and shared biological mechanisms

Inherited genetic variation impacts local gene expression and DNA methylation in humans. Expression and methylation quantitative trait loci (cis-eQTLs and cis-mQTLs) often occur at the same genomic location, suggesting a common causal variant and shared mechanism. Using DNA and RNA from peripheral blood of Bangladeshi individuals, we use \"co-localization\" methods to identify 3,695 eQTL-mQTL pairs that are likely to share a causal variant. Using partial correlation analysis and mediation analysis, we identify >500 pairs with evidence of a causal relationships between expression and methylation (i.e., shared mechanism) with many additional pairs that we are underpowered to detect. These co-localized pairs are enriched for SNPs showing opposite effects on expression and methylation, although a many affect multiple CpGs in opposite directions. Evidence of shared SNP-age interaction also supports shared mechanisms for two eQTL-mQTL pairs. This work demonstrates the pervasiveness of co-regulated expression and methylation traits in the human genome. This approach can be applied to other types of molecular QTLs to enhance our understanding of regulatory mechanisms.

genomics↗