Faculty of Biological Sciences

Elucidating Genetic and Epigenetic Mechanisms of Type 2 Diabetes Mellitus Pathogenesis

2026-10-18T09:34:12Z

Elucidating Genetic and Epigenetic Mechanisms of Type 2 Diabetes Mellitus Pathogenesis Barman, Nilima Type 2 diabetes mellitus (T2DM) is a rapidly escalating public health crisis in Bangladesh, which now ranks seventh globally, with approximately 13.9 million adults living with the disease. T2DM is a multifactorial disorder arising from complex interactions among genetic susceptibility, epigenetic dysregulation, and environmental exposures. Despite the growing burden, molecular-level evidence from Bangladeshi populations remains scarce. This study aimed to investigate the genetic, environmental, and epigenetic factors associated with T2DM in the Bangladeshi population by examining genetic variations in the TCF7L2 rs12255372 and SLC30A8 rs13266634 genes, exploring the association between adverse childhood experiences (ACEs) and adult T2DM risk, characterizing genome-wide DNA methylation alterations in T2DM, and assessing the potential mediating role of DNA methylation in the relationship between ACE exposure and T2DM susceptibility. A case-control study was conducted among Bangladeshi T2DM patients and healthy controls. Clinical, anthropometric, biochemical, and psychosocial data were collected, and ACE exposure was assessed using the standardized ACE questionnaire. Candidate gene polymorphisms were analyzed by PCR amplification and Sanger sequencing. The Structural consequences of the SLC30A8 rs13266634 substitution were investigated via molecular dynamics simulation. Genome-wide DNA methylation profiling was performed using whole-genome enzymatic methyl sequencing on peripheral blood-derived genomic DNA, followed by bioinformatic analysis using the nf-core/methylseq pipeline and differential methylation analyses with edgeR and DMRcate. Pathway enrichment analysis was conducted using Ingenuity Pathway Analysis. High-dimensional mediation analysis (HDMAX2) was applied to explore the potential mediating role of DNA methylation in the association between ACE and T2DM. The study demonstrated that both genetic and environmental factors contribute significantly to T2DM susceptibility in the Bangladeshi population. The TCF7L2 rs12255372 T allele was significantly associated with increased T2DM risk, with individuals carrying either GT or GT-TT genotypes showing higher odds of disease. Similarly, the SLC30A8 rs13266634 wild-type CC genotype and major C allele were associated with increased T2DM susceptibility, whereas the variant TT genotype x appeared to confer a protective effect. Molecular dynamics simulations further suggested that the ZnT8 p.R325W substitution increased structural rigidity and reduced conformational flexibility, potentially affecting zinc transport and insulin granule physiology. In addition to genetic susceptibility, ACEs were strongly associated with T2DM, as individuals exposed to four or more ACEs had more than two-fold higher risk of developing the disease. Genome-wide DNA methylation profiling identified 608 differentially methylated CpG sites, the majority of which were hypermethylated. Pathway enrichment analyses revealed epigenetic dysregulation in neurotransmitter signaling, fatty acid metabolism, adiponectin signaling, insulin resistance pathways, and mitochondrial regulation. Furthermore, high-dimensional mediation analysis identified multiple methylated loci potentially involved in the association between ACE exposure and T2DM, while pooled mediation analysis indicated that the indirect effect through DNA methylation accounted for approximately 41.1% of the total ACE–T2DM association. These findings provide statistical evidence consistent with a potential epigenetic pathway through which early-life adversity may influence adult metabolic disease risk, rather than establishing a definitive causal relationship. In conclusion, this study provides integrated evidence that genetic susceptibility, adverse childhood experiences, and epigenetic dysregulation collectively contribute to T2DM in the Bangladeshi population. The findings enhance understanding of the molecular mechanisms underlying T2DM and may contribute to future strategies for early risk prediction, prevention, and personalized management of diabetes in Bangladesh. This thesis is submitted for the degree of Doctor of Philosophy.

Diversity and Conservation of Wild Mammals and Tree Species in a Protected Area of Southeast Bangladesh

2026-10-18T09:30:46Z

Diversity and Conservation of Wild Mammals and Tree Species in a Protected Area of Southeast Bangladesh Das, Bipul Krishna Protected areas in torrid zone are progressively susceptible to habitat fragmentation, anthropogenic pressure, and governance limitations, elevating major issue about their efficacy in conserving biodiversity. This research was conducted between November 2022 and March 2026. This study illustrates and evaluates mammalian persistence, forest structure and regeneration, spatial distribution of biodiversity, threats analysis through community perceptions, and governance challenges to establish an empirical foundation for conservation and management of the Inani National Park, a fragmented critical tropical protected forest of southeastern Bangladesh. Field investigations were executed between November 2022 and June 2024, applying a multi-pronged approach. Consistent line transects and considerable camera trapping, generating over 4,700 trap-days of data were utilized for the estimation of mammalian diversity and persistence. Imperfect detection was determined through occupancy modeling, while species distribution modeling using the MaxEnt algorithm was applied to map habitat suitability and find out biodiversity hotspots. Stratified random sampling across 131 plots representing four land-cover strata were utilized for analyzing forest vegetation composition, structure, and regeneration dynamics of the park. Socio-ecological parameters were analyzed through structured community surveys (n=271) and semi-structured KII stakeholder interviews (n=43) for evaluation of community perceptions, human-wildlife conflict, and protected area governance potency. A total of 23 species of wild mammals, inclusive of globally threatened species were recorded during this study. Habitat heterogeneity such as undisturbed hill forests and shrub-dominated mosaics assisting the highest diversity significantly impacted mammalian richness and persistence, especially during the monsoon. It is very enthusiastic that the first confirmed photographic and field evidence of a few survivals population of the threatened species clouded leopard (Neofelis nebulosa) in degraded protected forest, Inani National Park (INP) was identified through the study. Occupancy modeling divulged nearly finished sites used by the Asian Elephant, while evasive carnivores such as the clouded leopard exhibits low detection probability and confined occupancy, validating the persistence of a minuscule and vulnerable population. Species distribution models pinpointed profound biodiversity hotspots such as riparian corridors and southern forest patches, accentuated their significance for habitat connectivity within the fragmented forest landforms. In total 66 tree species across 33 families and 90 regenerating species were recorded through vegetation analyses, which indicating average but spatially uneven diversity. Shrub-dominated strata demonstrated higher species richness and regeneration potential, whereas plantation and heavily modified areas showed simplified structure and limited recruitment of late-successional species. The dominance of invasive and pioneer taxa exhibits ongoing disturbance and ecological imbalance. Taken as a whole, this dissertation confirmed Inani National Park as a biologically important yet extremely vulnerable refuge and ecological corridor. By incorporating ecological, spatial, and governance analyses, the research offers a comprehensive conservation foundation highlighting habitat restoration, assisted natural regeneration, protection of riparian corridors, conflict mitigation, and strengthened participatory governance. The findings furnish to more extensive insight of protected area effectiveness in the Global South and suggest implementation guidelines for biodiversity conservation and better management in degraded tropical landscapes. This thesis is submitted for the degree of Doctor of Philosophy.

Study of Zooplankton diversity in two selected lakes in Dhaka city, Bangladesh

2026-08-09T08:33:53Z

Study of Zooplankton diversity in two selected lakes in Dhaka city, Bangladesh Sikder, Shilpi Rani Urban aquatic ecosystems are essential components of the urban environment, playing crucial ecological roles such as water purification, habitat provision, and biodiversity support. Despite their immense significance, these ecosystems face numerous challenges due to climate change and anthropogenic pressures. Therefore, this study aimed to investigate the zooplankton diversity in Dhanmondi and Ramna Lakes, two major urban water bodies in Dhaka, Bangladesh, to understand the influence of different environmental parameters and seasonal changes on the abundance and composition of zooplankton between April 2022 and August 2023. Zooplankton were sampled from eight stations per lake during the dry and wet seasons using a 64-μm plankton net, and water quality parameters (temperature, pH, DO, conductivity, salinity, TDS) were measured in situ. Quantitative estimation and identification were conducted using Sedgewick–Rafter counting and standard taxonomic keys. Statistical analyses included ANOVA, correlation, and multivariate regression. A total of 53 taxa were recorded, with 34 taxa in Dhanmondi and 19 in Ramna. Branchiopoda were the dominant group in both lakes (53–55%), while Bdelloidea and Insecta were least abundant. Seasonal variation showed consistently higher dominance of Branchiopoda in both seasons, whereas Bdelloidea and Flagellata remained low. Water quality comparison revealed a significant difference only in TDS (p < 0.001). Correlation analysis showed strong negative relationships between temperature and DO, while regression indicated DO and pH as the main predictors of zooplankton abundance, explaining 36–37% of the variation.This findings are not only vital for preserving biodiversity but also for ensuring the proper management of these two vital urban ecosystems as it revealed the zooplankton community dynamics as well as their seasonal variability. Furthermore, the findings of this study will inform improved conservation and management practices so that the urban lakes continue to thrive and provide essential ecological services. This thesis is submitted for the degree of Master of Philosophy.

Ichthyo diversity of Jamuna river, Sirajganj, Bangladesh

2026-08-09T08:23:58Z

Ichthyo diversity of Jamuna river, Sirajganj, Bangladesh Akter, Mst. Ashifa Millions of people depend on Bangladesh's river systems, which are among the most productive and biodiverse in the world. However, fish populations are under risk due to frequent environmental changes, which renders baseline research crucial for conservation. This study examined the seasonal variations of the fish species in the Jamuna River, Bangladesh, over a 12-month period of about 12-months from July 2022 to June 2023. The research aimed to understand how seasonal changes in this large and significant tropical river system affected fish diversity, abundance, and community composition. The Jamuna River, known for its dynamic hydrological conditions and diverse aquatic habitats, provides a unique environment to study the complex interactions between fish species and their environment. Understanding these seasonal patterns of the ichthyo diversity is crucial for maintaining the health and sustainability of fish populations, which are an important resource for local communities and ecosystems. Over the study period, a total of 79 distinct fish species, belonging to 10 orders and 27 families were identified and monitored to determine their abundance across different seasons. The study employed heat maps and diversity indices to analyze seasonal abundance patterns. Heat maps offered a visual representation of the distribution and concentration of species over time, while diversity indices quantified changes in species richness (number of different species), evenness (relative abundance of species), and overall diversity. These analytical tools provided a comprehensive overview of how fish communities varied in response to seasonal changes in the river's flow, temperature, and habitat conditions. The findings revealed clear and distinct seasonal trends in fish abundance. Several species, such as Hyporhamphus limbatus and Xenentodon cancila, were found to be more abundant during the rainy season, which corresponds to the monsoon period in Bangladesh. On the other hand, species such as Setipinna phasa, Chanda nama, Gagata youssoufi were observed to have higher abundances in the dry season, when water levels are lower. The findings from this study underscore the importance of understanding the natural seasonal variability of fish populations. Further research is needed to explore the specific ecological drivers behind these seasonal patterns and to evaluate the long-term impacts of environmental changes on fish communities in the Jamuna River and for developing management and conservation strategies. This thesis is submitted for the degree of Master of Philosophy.