Biology subjects

Pandey, A. K.

Publications and source records attributed to Pandey, A. K..

49 records · Page 3Linked to original sources

bioRxiv2020

Signature of selection in composite Vrindavani cattle of India

Vrindavani is an Indian composite cattle breed developed by crossbreeding taurine dairy breeds with native indicine cattle in the 1960s. About 190,000 semen doses of Vrindavani bulls have been distributed to the farmers till date. The animals are under artificial and natural selection for higher milk production and adaptation to the tropical climate, respectively. However, the selection response for production and adaptation traits in the Vrindavani genome is not explored. In this study, we provide the first overview of the selection signatures in the Vrindavani genome. 96 Vrindavani cattle were genotyped using the BovineSNP50 BeadChip and the SNP genotype data of its constituent breeds were collected from a public database. Within-breed selection signatures in Vrindavani were investigated using the integrated haplotype score (iHS). Vrindavani was also compared to each of its parental breeds to discover between-population signatures of selection using two approaches, cross-population extended haplotype homozygosity (XP-EHH) and fixation index (FST). Selection of signature identifies 11 common region identified by more than one harbouring genes such as LRP1B, TNNI3K, APOB, CACNA2D1, FAM110B and SPATA17 associated with production and adaptation. Overall, our results suggested stronger selective pressure on regions responsible for adaptation compared to milk yield.

genetics↗

bioRxiv2020

Multivariate GWAS elucidates the genetic architecture of alcohol consumption and misuse, corrects biases, and reveals novel associations with disease

Genome-wide association studies (GWASs) of the Alcohol Use Disorder Identification Test (AUDIT), a ten-item screener for alcohol use disorder (AUD), have elucidated novel loci for alcohol consumption and misuse. However, these studies also revealed that GWASs can be influenced by numerous biases (e.g., measurement error, selection bias), which have led to inconsistent genetic correlations between alcohol involvement and AUD, as well as paradoxically negative genetic correlations between alcohol involvement and psychiatric disorders/medical conditions. To explore these unexpected differences in genetic correlations, we conducted the first item-level and largest GWAS of AUDIT items (N=160,824), and applied a multivariate framework to mitigate previous biases. In doing so, we identified novel patterns of similarity (and dissimilarity) among the AUDIT items, and found evidence of a correlated two-factor structure at the genetic level (Consumption and Problems, rg=.80). Moreover, by applying empirically-derived weights to each of the AUDIT items, we constructed an aggregate measure of alcohol consumption that is strongly associated with alcohol dependence (rg=.67) and several other psychiatric disorders, and no longer positively associated with health and positive socioeconomic outcomes. Lastly, by performing polygenic analyses in three independent cohorts that differed in their ascertainment and prevalence of AUD, we identified novel genetic associations between alcohol consumption, alcohol misuse, and human health. Our work further emphasizes the value of AUDIT for both clinical and genetic studies of AUD, and the importance of using multivariate methods to study genetic associations that are more closely related to AUD.

genetics↗

bioRxiv2020

Genetic screen to saturate guard cell signaling network reveals a role of GDP-L-fucose metabolism in stomatal closure

Guard cells regulate plant gas exchange by controlling the aperture of stomatal pores. The process of stomatal closure involves a multi-input signaling network that governs the activity of ion channels, which in turn regulate guard cell turgor pressure and volume. Here we describe a forward genetic screen to identify novel components involved in stomatal movements. Through an ozone-sensitivity approach combined with whole-rosette gas exchange analysis, 130 mutants of established stomatal regulators and 76 novel mutants impaired in stomatal closure were identified. One of the novel mutants was mapped to MURUS1 (MUR1), the first enzyme in de novo GDP-L-fucose biosynthesis. Defects in synthesis or import of GDP-L-Fuc into the Golgi apparatus resulted in impaired stomatal closure to multiple stimuli. Stomatal phenotypes observed in mur1 were independent from the canonical guard cell signaling and instead could be related to altered mechanical properties of guard cell walls. Impaired fucosylation of xyloglucan, N-linked glycans and arabinogalactan proteins did not explain the aberrant function of mur1 stomata, however our data suggest that the stomatal phenotypes observed in mur1 can at least partially be attributed to defective dimerization of rhamnogalactouronan-II. In addition to providing the genetic framework for future studies on guard cell signaling, our work emphasizes the impact of fucose metabolism on stomatal movement.

plant biology↗

bioRxiv2020

Underpinning wheat physiological and molecular responses to co-occurring iron and phosphate deficiency stress

Iron (Fe) and phosphorus (P) are the essential mineral nutrient for plant growth and development. However, the molecular interaction of the Fe and P pathways in crops remained largely obscure. In this study, we provide a comprehensive physiological and molecular analysis of hexaploid wheat response to single (Fe, P) and its combinatorial deficiencies. Our data showed that inhibition of the primary root growth occurs in response to Fe deficiency; however, growth was rescued when combinatorial deficiencies occurred. Analysis of RNAseq revealed that distinct molecular rearrangements during combined deficiencies with predominance for genes related to metabolic pathways and secondary metabolite biosynthesis primarily include genes for UDP-glycosyltransferase, cytochrome-P450s, and glutathione metabolism. Interestingly, the Fe-responsive cis-regulatory elements in the roots in Fe stress conditions were enriched compared to the combined stress. Our metabolome data also revealed the accumulation of distinct metabolites such as amino-isobutyric acid, arabinonic acid, and aconitic acid in the combined stress environment. Overall, these results are essential in developing new strategies to improve the resilience of crops in limited nutrients. HIGHLIGHTSO_LIThis study was performed to understand the molecular changes occurring during the interaction of Phosphorus (P) and Iron (Fe) in hexaploid wheat roots. C_LIO_LIP and Fe show cross-talk as Fe deficiency-induced phenotype that was restored by the withdrawal of P. C_LIO_LIA total of 2780 differentially expressed genes were identified in the roots with the combined -Fe-P deficiencies with predominance for UDP-glycosyltransferases, cytochrome-450 and glutathione-S-transferases transcripts. C_LIO_LIThe metabolomic changes identified the importance of amino-isobutyric acid, arabinonic acid and aconitic acid during dual deficiency C_LIO_LIThis work provides a comprehensive insight to understand the molecular rearrangements occurring in wheat roots during Fe and P interaction. C_LI

plant biology↗

bioRxiv2020

Mutation landscape of SARS-CoV-2 reveals three mutually exclusive clusters of leading and trailing single nucleotide substitutions

The COVID-19 pandemic has spread across the globe at an alarming rate. However, unlike any of the previous global outbreaks the availability of a large number of SARS-CoV-2 sequences provides us with a unique opportunity to understand viral evolution in real time. We analysed 1448 full-length (>29000 nt) sequences available and identified 40 single-nucleotide substitutions occurring in >1% of the genomes. Majority of the substitutions were C to T or G to A. We identify C/Gs with an upstream TTT trinucleotide motif as hotspots for mutations in the SARS-CoV-2 genome. Interestingly, three of the 40 substitutions occur within highly conserved secondary structures in the 5 and 3 regions of the genomic RNA that are critical for the virus life cycle. Furthermore, clustering analysis revealed unique geographical distribution of SARS-CoV-2 variants defined by their mutation profile. Of note, we observed several co-occurring mutations that almost never occur individually. We define five mutually exclusive lineages (A1, B1, C1, D1 and E1) of SARS-CoV-2 which account for about three quarters of the genomes analysed. We identify lineage-defining leading mutations in the SARS-CoV-2 genome which precede the occurrence of sub-lineage defining trailing mutations. The identification of mutually exclusive lineage-defining mutations with geographically restricted patterns of distribution has potential implications for diagnosis, pathogenesis and vaccine design. Our work provides novel insights on the temporal evolution of SARS-CoV-2. ImportanceThe SARS-CoV-2 / COVID-19 pandemic has spread far and wide with high infectivity. However, the severeness of the infection as well as the mortality rates differ greatly across different geographic areas. Here we report high frequency mutations in the SARS-CoV-2 genomes which show the presence of linage-defining, leading and trailing mutations. Moreover, we propose for the first time, five mutually exclusive clusters of SARS-CoV-2 which account for 75% of the genomes analysed. This will have implications in diagnosis, pathogenesis and vaccine design

genomics↗

bioRxiv2020

An Inherent Structural Difference Between Serine and Threonine Phosphorylation: Phosphothreonine Prefers an Ordered, Compact, Cyclic Conformation

Phosphorylation and dephosphorylation of proteins by kinases and phosphatases are central to cellular responses and function. The structural effects of serine and threonine phosphorylation were examined in peptides and in proteins, by circular dichroism, NMR spectroscopy, bioinformatics analysis of the PDB, small-molecule X-ray crystallography, and computational investigations. Phosphorylation of both serine and threonine residues induces substantial conformational restriction in their physiologically more important dianionic forms. Threonine exhibits a particularly strong disorder-to-order transition upon phosphorylation, with dianionic phosphothreonine preferentially adopting a cyclic conformation with restricted{phi} ({phi} [~] -60{degrees}) stabilized by three noncovalent interactions: a strong intraresidue phosphate-amide hydrogen bond, an n[->]{pi}* interaction between consecutive carbonyls, and an n[->]{sigma}* interaction between the phosphate O{gamma} lone pair and the antibonding orbital of C-H{beta} that restricts the{chi} 2 side chain conformation. Proline is unique among the canonical amino acids for its covalent cyclization on the backbone. Phosphothreonine can mimic prolines backbone cyclization via noncovalent interactions. The preferred torsions of dianionic phosphothreonine are{phi} ,{psi} = polyproline helix or -helix ({phi} [~] -60{degrees});{chi} 1 = g-;{chi} 2 = eclipsed C-H/O-P bonds. This structural signature is observed in diverse proteins, including the activation loops of protein kinases and protein-protein interactions. In total, these results suggest a structural basis for the differential use and evolution of threonine versus serine phosphorylation sites in proteins, with serine phosphorylation typically inducing smaller, rheostat-like changes, versus threonine phosphorylation promoting larger, step function-like switches, in proteins.

biophysics↗

bioRxiv2020

Uncanny similarity of unique inserts in the 2019-nCoV spike protein to HIV-1 gp120 and Gag

We are currently witnessing a major epidemic caused by the 2019 novel coronavirus (2019-nCoV). The evolution of 2019-nCoV remains elusive. We found 4 insertions in the spike glycoprotein (S) which are unique to the 2019-nCoV and are not present in other coronaviruses. Importantly, amino acid residues in all the 4 inserts have identity or similarity to those in the HIV-1 gp120 or HIV-1 Gag. Interestingly, despite the inserts being discontinuous on the primary amino acid sequence, 3D-modelling of the 2019-nCoV suggests that they converge to constitute the receptor binding site. The finding of 4 unique inserts in the 2019-nCoV, all of which have identity /similarity to amino acid residues in key structural proteins of HIV-1 is unlikely to be fortuitous in nature. This work provides yet unknown insights on 2019-nCoV and sheds light on the evolution and pathogenicity of this virus with important implications for diagnosis of this virus.

evolutionary biology↗

bioRxiv2019

Gene expression pattern of vacuolar-iron transporter-like (VTL) genes in hexaploid wheat during metal stress

Iron is one of the important micronutrients that is not just essential for the human body, but also required for crop productivity and yield-related traits. To address the Fe homeostasis in crop plants, multiple transporters belonging to the category of Major facilitator superfamily are being explored. In this direction, Vacuolar iron transporters (VIT) are being reported and have been characterized functionally as an important candidate to address biofortification in cereal crops. In the present study, the identification and characterization of new members of Vacuolar iron transporters-like proteins (VTL) was performed. Phylogenetic analyses demonstrated distinct clustering of all the VTL genes from the previously known VIT genes. Our analysis identifies multiple VTL genes from hexaploid wheat with the highest number of this gene family localized on chromosome 2. Quantitative expression analysis suggests that most of the VTL genes are induced only during the Fe surplus condition, thereby reinforcing their role metal homeostasis. Interestingly, most of the wheat VTL genes were significantly up-regulated in a tissue-specific manner under Zn, Mn and Cu deficiency conditions. Although, no significant changes in expression of wheat VTL genes were observed in roots under heavy metals, but TaVTL2, TaVTL3 and TaVTL5 were upregulated in the presence of cobalt stress. Overall, this work deals with the characterization of wheat VTL genes that could provide an important genetic resource for addressing metal homeostasis in bread wheat.

plant biology↗

bioRxiv2019

Host cholesterol dependent activation of VapC12 toxin enriches persister population during Mycobacterium tuberculosis infection

A worldwide increase in the frequency of multidrug-resistant and extensively drug-resistant cases of tuberculosis is mainly due to therapeutic noncompliance associated with a lengthy treatment regimen. Depending on the drug susceptibility profile, the treatment duration can extend from 6 months to 2 years. This protracted regimen is attributed to a supposedly non-replicating and metabolically inert subset of the Mycobacterium tuberculosis (Mtb) population, called persisters. The mechanism underlying stochastic generation and enrichment of persisters is not fully known. We have previously reported that the utilization of host cholesterol is essential for mycobacterial persistence. In this study, we have demonstrated that cholesterol-induced activation of a ribonuclease toxin (VapC12) inhibits translation by targeting proT tRNA in Mtb. This results in cholesterol-specific growth modulation that increases the frequency of the generation of persisters in a heterogeneous Mtb population. Also, a null mutant strain of this toxin ({Delta}vapC12) failed to persist and demonstrated an enhanced growth phenotype in a guinea pig model of Mtb infection. Thus, we have identified a novel strategy through which cholesterol-specific activation of a toxin-antitoxin (TA) module in Mtb enhances persister formation during infection. In addition to identifying the mechanism, the study provides opportunity for targeting persisters, a new paradigm facilitating tuberculosis drug development.

microbiology↗

bioRxiv2019

Wheat inositol pyrophosphate kinase (TaVIH2-3B) interacts with Fasciclin-like arabinogalactan (FLA6) protein and alters the plant cell-wall composition

BackgroundInositol pyrophosphates (PP-InsPs) are high-energy cellular molecules involved in different signalling and regulatory responses. Two distinct classes of inositol phosphate kinases responsible for the synthesis of PP-InsPs have been identified in Arabidopsis i.e. ITPKinase (inositol 1,3,4 trisphosphate 5/6 kinase) and PP-IP5Kinase (diphosphoinositol pentakisphosphate kinases). Plant PP-IP5Ks are capable of synthesizing InsP8 and were shown to control pathogenic defence and phosphate response signals. However, other roles offered by plant PP-IP5Ks, especially towards abiotic stress, remain poorly understood. ResultsHere, we characterized two Triticum aestivum L. (hexaploid wheat) PPIP5K homologs, TaVIH1 and TaVIH2, for their physiological functions. We demonstrated that wheat VIH proteins could utilize InsP7 as the substrate to produce InsP8, a process that requires the functional VIH-kinase domains. At the transcriptional level, both TaVIH1 and TaVIH2 are expressed in different wheat tissues, including developing grains, but show selective response to abiotic stresses during drought-mimic experiments. Overexpression of TaVIH2-3B homolog in Arabidopsis conferred tolerance to drought stress and rescued the sensitivity of Atvih2 mutants. RNAseq analysis of TaVIH2-3B transgenic lines of Arabidopsis showed a genome-wide reprogramming with remarkable effects on cell-wall biosynthesis genes with enhanced the accumulation of polysaccharides (arabinogalactan, cellulose and arabinoxylan). ConclusionsOverall, this work identifies a novel function of VIH proteins, implying their roles in modulating cell-wall homeostasis genes and providing water-deficit stress tolerance. This work suggests that the plant VIH enzymes could be linked to drought tolerance and also opens up investigations to address the roles of plant VIH derived products in generating drought resistant plants.

plant biology↗

bioRxiv2019

Overlapping transcriptional expression response of wheat zinc-induced facilitator-like transporters emphasize important role during Fe and Zn stress

BackgroundHexaploid wheat is an important cereal crop that has been targeted to enhance grain micronutrient content including zinc and iron. In this direction, modulating the expression of plant transporters involved in Fe and Zn homeostasis could be one of the promising approaches. Therefore, the present work was undertaken to identify bread wheat Zinc-Induced Facilitator-Like (ZIFL) family of transporters and study their transcriptional expression response during micronutrient fluctuations and exposure to multiple heavy metals.\n\nResultsThe genome-wide analyses resulted in identification of thirty-five putative TaZIFL genes, which were distributed only on Chromosome 3, 4 and 5. Wheat ZIFL proteins subjected to the phylogenetic analysis showed the uniform distribution along with rice, Arabidopsis and maize. In-silico analysis of the promoters of the wheat ZIFL genes suggested the presence of multiple metal binding sites including those which are involved in Fe homeostasis. QRT-PCR analysis of wheat ZIFL genes suggested the differential regulation of the transcripts in roots and shoots under surplus Zn and also during Fe starvation. Specifically, in roots, TaZIFL2.3, TaZIFL4.1, TaZIFL4.2, TaZIFL5, TaZIFL6.1 and TaZIFL6.2 were significantly up-regulated by both Zn and Fe. This suggested that ZIFL could possibly be regulated by both the nutrient stress in a tissue specific manner. Interestingly, upon exposure to heavy metals, TaZIFL4.2 and TaZIFL7.1 showed significant up-regulation, whereas TaZIFL5 and TaZIFL6.2 remained almost unaffected.\n\nConclusionThis is the first report with detailed analysis of wheat ZIFL genes. Our study also identifies closest ortholog for transporter of mugineic acid, a chelator required for Fe uptake. Comprehensive transcript expression pattern during development of wheat seedlings and against various abiotic/biotic stresses resulted in tissue specific responses. Overall, this work addresses the role of wheat ZIFL during the interplay between micronutrient and heavy metal stress in a tissue specific manner.

plant biology↗

bioRxiv2019

Genome-wide expression analysis identifies core components during iron starvation in hexaploid wheat

Iron is one of essential micronutrient for all organisms. Its deficiency causes a severe loss in crops yield. Nevertheless, our current understanding on major crops response to Fe deficiency remains limited. Herein, we investigated the effect of Fe deprivation at both transcriptomic and metabolic levels in hexaploid wheat. A genome-wide gene expression reprogramming was observed with a total of 5854 genes showing differential expression in roots of wheat subjected to Fe-starved medium. Subsequent, analysis revealed a predominance of strategy-II mode of Fe uptake, with induced genome bias contribution from the A and B genomes. In general, the predominance of genes encoding for nicotianamine synthase, yellow stripe like transporters, metal transporters, ABC transporters and zinc-induced facilitator-like protein was noticed. Our transcriptomic data were in agreement with the GC-MS analysis that showed an enhancement of accumulation of various metabolites such as fumarate, malonate, succinate and xylofuranose, which could be linked for enhancing Fe-mobilization. Interestingly, Fe starvation causes a significant temporal increase of glutathione-S-transferase both at transcriptional and enzymatic activity, which indicate the important role of glutathione in the response to Fe starvation in wheat roots. Taken together, our result provides new insight on wheat response to Fe starvation and lays foundation to design strategies to improve Fe nutrition in crops.

plant biology↗

bioRxiv2017

MutS-Homolog2 Silencing Generates Tetraploid Meiocytes In Tomato (Solanum lycopersicum)

MSH2 is the core protein of MutS-homolog family involved in recognition and repair of the errors in the DNA. While other members of MutS-homolog family reportedly regulate mitochondrial stability, meiosis, and fertility, MSH2 is believed to participate mainly in mismatch repair. The search for polymorphism in MSH2 sequence in tomato accessions revealed both synonymous and nonsynonymous SNPs; however, SIFT algorithm predicted that none of the SNPs influenced MSH2 protein function. The silencing of MSH2 gene expression by RNAi led to phenotypic abnormalities in highly-silenced lines, particularly in the stamens with highly reduced pollen formation. MSH2 silencing exacerbated formation of UV-B induced thymine dimers and blocked light-induced repair of the dimers. The MSH2 silencing also affected the progression of male meiosis to a varying degree with either halt of meiosis at zygotene stage or formation of diploid tetrads. The immunostaining of male meiocytes with centromere localized CENPC (Centromere protein C) protein antibody showed the presence of 48 univalent along with 24 bivalent chromosomes suggesting abnormal tetraploid meiosis. The mitotic cells of root tips of silenced lines showed diploid nuclei but lacked intervening cell plates leading to cells with syncytial nuclei. Thus we speculate that tetraploid pollen mother cells may have arisen due to the fusion of syncytial nuclei before the onset of meiosis. It is likely that in addition to Mismatch repair (MMR), MSH2 may have an additional role in regulating ploidy stability.

plant biology↗