Biology subjects

Rahman, S. R.

Publications and source records attributed to Rahman, S. R..

6 recordsLinked to original sources

bioRxiv2026

Effects of vapor inhalation of 6-methyl nicotine in female and male rats

Background: The nicotine analog 6-methyl nicotine (6-MN) has appeared in commercial e-cigarette liquids, and other products, spurring interest in determining the extent to which it conveys similar effects to those of nicotine. Objective: To determine if 6-MN acts like nicotine to decrease body temperature, decrease nociception, suppress wheel activity and reinforce operant behavior when delivered by vapor inhalation using an Electronic Nicotine Delivery System (ENDS; "e-cigarette") approach in a rat model. Methods: Male and female (N=8 per sex) young adult Sprague-Dawley rats were evaluated for rectal temperature and nociceptive responses (warm water tail-withdrawal) to the inhalation of vapor from (-)-6-MN or (-)-nicotine in concentrations ranging from 5-30 mg/mL in the propylene glycol vehicle. Rats were then assessed for the reinforcing effects of nicotine and 6-MN using a vapor self-administration procedure and the rate suppressing effects of nicotine and 6-MN on wheel activity following injection. Results: Inhalation of nicotine or 6-MN for 30 minutes decreased the rectal temperature and increased tail-withdrawal latency of female and male rats in a concentration-dependent manner. The magnitude of the effects of 6-MN and nicotine were similar at similar vapor concentrations. Operant responding for 6-MN vapor was increased by pre-treatment with the antagonist mecamylamine. 6-MN was more potent than nicotine at suppressing wheel activity after injection. Conclusions: 6-MN induces effects very similar to those of nicotine, at a similar potency when inhaled and at a slightly increased potency when injected.

pharmacology and toxicology↗

bioRxiv2023

Phylogenetic diversity and functional potential of large and cell-associated viruses in the Bay of Bengal

The Bay of Bengal (BoB), the largest bay in the world, provides valuable ecosystem services such as fishing and recreation to millions of people living along its coast and has a significant economic value. The BoB is impacted by various environmental factors such as seasonal monsoons and multiple freshwater inputs, and this region is particularly vulnerable to sea-level rise and increased frequency of devastating cyclones that are predicted to be exacerbated due to global climate change. These factors are also compounded by anthropogenic influences from tourism and development, making it an important ecosystem to understand and study from a global change perspective. Despite its importance, microbial diversity and ecology have remained largely understudied in this region. In this study, we describe the diversity and putative functional importance of large and cell-associated (that is, originating from the cellular size fraction) viruses from two coastal sites in the BoB, with an emphasis on giant viruses and large phages. Sites chosen for this study include Coxs Bazar, a populated beach with multiple freshwater inputs, and Saint Martin Island, a resort island that has considerably less human influence compared to Coxs Bazar. Through metagenomic sequencing, we were able to identify a more abundant and more diverse viral community at Coxs Bazar consisting of many viruses that are indicators of freshwater intrusion and runoff. Overall, 1962 putative phage genome bins were obtained ranging from 10 - 655 kilobase pairs (kbp) in sizes. Of these genomes, 16 from Saint Martin were found to be larger than 100kbp which we deemed "large" phages, and we were able to reconstruct a phylogeny of these large phages using the TerL gene as a marker. This phylogeny revealed clades enriched in large phages and a high diversity of large phage candidates in the Bay of Bengal coast. Protein annotation analysis showed a wide variety of functionality from both sites with more auxiliary metabolic genes (AMGs) found in the Coxs Bazar viral community. Five giant virus (Phylum Nucleocytoviricota) genomes were also reconstructed from Coxs Bazar and identified as belonging to the orders Imitervirales and Pandoravirales. These genomes ranged from 83 - 876 kbp in size and contained a wide range of encoded functionalities. To the best of our knowledge, our study represents the first insights on the phylogenetic and functional diversity of viruses in the Bay of Bengal. These results thus provide an important foundation for further studies on the impact of host-virus interactions on biogeochemical cycles and microbial food web in this understudied marine environment.

microbiology↗

bioRxiv2023

Constitutive and variable patterns of genome-wide DNA methylation in populations from spatial-environmental range extremes of the bumble bee Bombus vosnesenskii

Unraveling molecular mechanisms of adaptation to complex environments is crucial to understanding tolerance of abiotic pressures and responses to climatic change. Epigenetic variation is increasingly recognized as a mechanism that can facilitate rapid responses to changing environmental cues. To investigate variation in genetic and epigenetic diversity at spatial and thermal extremes, we use whole genome and methylome sequencing to generate a high-resolution map of DNA methylation in the bumble bee Bombus vosnesenskii. We sample two populations representing spatial and environmental range extremes (a warm southern low-elevation site and a cold northern high-elevation site) previously shown to exhibit differences in thermal tolerance and determine positions in the genome that are constitutively and variably methylated across samples. Bisulfite sequencing reveals methylation characteristics similar to other arthropods, with low global CpG methylation but high methylation concentrated in gene bodies and in genome regions with low nucleotide diversity. Differentially methylated sites (n = 2,066) were largely hypomethylated in the northern high-elevation population but not related to local sequence differentiation. The concentration of methylated and differentially methylated sites in exons and putative promoter regions suggests a possible role in gene regulation, and this high-resolution analysis of intraspecific epigenetic variation in wild Bombus suggests that the function of methylation in niche adaptation would be worth further investigation.

genomics↗

bioRxiv2023

Exploring Microbial Diversity and Functional Potential along the Bay of Bengal Coastline in Bangladesh: Insights from Amplicon Sequencing and Shotgun Metagenomics

Although the Bay of Bengal (BoB) is the worlds largest bay, possessing distinct physiochemical properties, it has garnered little research focus concerning its microbial diversity and ecological importance. Here, we present amplicon (16S and 18S) profiling and shotgun metagenomics data regarding microbial communities from BoBs eastern coast, viz., Saint Martin and Coxs Bazar, Bangladesh. From the 16S sequencing data, Proteobacteria appeared to be the dominant phylum in both locations, with Alteromonas, Methylophaga, Anaerospora, Marivita, and Vibrio dominating in Coxs Bazar and Pseudoalteromonas, Nautella, Marinomonas, Vibrio, and Alteromonas dominating the Saint Martin site. From the 18S sequencing data, Ochrophyta, Chlorophyta, and Protalveolata appeared among the most abundant eukaryotic divisions in both locations, with significantly higher abundance of Choanoflagellida, Florideophycidae, and Dinoflagellata in Coxs Bazar. Functional annotations revealed that the microbial communities in these samples harbor genes for biofilm formation, quorum sensing, xenobiotics degradation, antimicrobial resistance, and a variety of other processes. Together, these results provide the first molecular insight into the functional and phylogenetic diversity of microbes along the BoB coast of Bangladesh and lay the foundation for further in-depth assessment of microbial community dynamics and functional potential in the context of global change in this region.

microbiology↗

bioRxiv2022

fastman: A fast algorithm for visualizing GWAS results using Manhattan and Q-Q plots

Visualisation of GWAS summary statistics, specifically P-values, as Manhattan plots are widespread in GWAS publications, and many popular software tools are available, such as the R package qqman. However, there is a substantial need for further development, such as handling datasets from non-model organisms. We provide a new R package, fastman, with major additional capabilities compared to currently available packages. For example, it handles datasets involving genomes from non-model organisms, even at a draft stage consisting of numerous contigs and scaffolds (shorter stretches of assembled DNA sequences) that have not been compiled into chromosomes. Non-numeric chromosome IDs are also supported. Additionally, our package has the capability of plotting other genetic scores, such as other GWAS statistics (e.g. regression betas or odds ratios), fixation index(FST), D-statistics, and various selection statistics, such as PBS. Importantly, negative or two-tailed values are supported in this package. In our package, we implement a heuristic algorithm that drastically reduces plotting time for huge datasets without losing visual precision, allowing for many different data types and missing data. We also provide substantial additional flexibility in highlighting and annotation. The package can produce plots directly from association outputs by PLINK. Alternatively, it can produce plots from any R data frame with custom columns and can handle large datasets to generate plots rapidly. It is available for public use at https://github.com/adhikari-statgen-lab/fastman.

bioinformatics↗

bioRxiv2020

A combined RAD-Seq and WGS approach reveals the genomic basis of yellow colour variation in bumble bee Bombus terrestris

BackgroundIn the model bumble bee species B. terrestris, both males and females exhibit black coloration on the third thoracic and first metasomal segments. We discovered a fortuitous lab-generated mutant in which this typical black coloration is replaced by yellow. As this same color variant is found in several sister lineages to B. terrestris within the Bombus s.s. subgenus, this could be a result of ancestral allele sorting. ResultsUtilizing a combination of RAD-Seq and whole-genome re-sequencing approaches, we localized the color-generating variant to a single SNP in the protein-coding sequence of a homeobox transcription factor, cut. Sanger sequencing confirmed fixation of this SNP between wildtype and yellow mutants. Protein domain analysis revealed this SNP to generate an amino acid change (Ala38Pro) that modifies the conformation of coiled-coil structural elements which lie outside the characteristic DNA binding domains. We found all Hymenopterans including B. terrestris sister lineages possess the non-mutant allele, indicating different mechanism(s) are involved in the same black to yellow transition in nature. ConclusionsCut is a highly pleiotropic gene important for multiple facets of development, yet this mutation generated no noticeable external phenotypic effects outside of setal characteristics. Reproductive capacity was observed to be reduced, however, with queens being less likely to mate and produce female offspring, in a manner similar to workers. Our research implicates a novel developmental player in pigmentation, and potentially caste as well, thus contributing to a better understanding of the evolution of diversity in both of these processes.

genomics↗