Akter, M. A. | Search bioRxiv

bioRxiv2025

DECREASE IN DNA METHYLATION 1-mediated epigenetic regulation maintains gene expression balance required for heterosis in Arabidopsis thaliana

Heterosis, or hybrid vigor, is characterized by superior phenotypic performance in F hybrids compared to their parental lines, and its expression is influenced by both genetic and epigenetic factors. In this study, we investigated the role of epigenetic regulation, particularly DNA methylation mediated by DECREASE IN DNA METHYLATION 1 (DDM1), in early seedling biomass heterosis using hybrids between Arabidopsis thaliana accessions Columbia-0 and C24. Loss of DDM1 function in F hybrids resulted in a significant reduction of rosette diameter, confirming that DDM1 is essential for heterosis. Transcriptomic and epigenomic analyses revealed extensive genotype-specific changes in gene expression and DNA methylation patterns in ddm1 mutants. Notably, ddm1-F hybrids exhibited upregulation of genes categorized into xyloglucan:xyloglucosyl transferase activity and downregulation of genes categorized into circadian rhythm, which may contribute to reduced growth vigor. Whole-genome bisulfite sequencing showed widespread hypomethylation in ddm1 mutants, yet the overlap between differentially methylated and expressed genes was limited, suggesting indirect or context-dependent regulatory effects. Additionally, we examined the role of salicylic acid (SA) in heterosis using SA-deficient mutants and found that variations in endogenous SA levels did not correlate with biomass heterosis under normal conditions. Our findings suggest that heterosis in A. thaliana is dependent on the maintenance of parental epigenetic divergence, particularly in DNA methylation patterns mediated by DDM1. Disruption of DDM1 compromises this epigenetic complementarity, leading to transcriptomic imbalances that reduce heterosis. HighlightLoss of DDM1 reduces biomass heterosis in Arabidopsis thaliana hybrids by disrupting DNA methylation and transcriptome stability, revealing a novel salicylic acid-independent epigenetic mechanism.

plant biology↗

bioRxiv2024

Design of a novel epitope-based tetravalent subunit vaccine against dengue virus: an immunoinformatics approach

Dengue imposes a profound global impact, with millions affected annually. Its transmission by Aedes mosquitoes poses significant challenges to combat, aggravated by urbanization and climate change. Despite efforts, no impeccable antiviral treatment exists to date, highlighting the urgency for a vaccine. Developing one encounters hurdles like the four distinctive serotypes of the virus and complex immune responses. In this study, we employed an immunoinformatics approach to design an epitope-based tetravalent subunit vaccine aimed at confronting all DENV serotypes. The study contemplates epitopes prediction, toxicity assessment, molecular docking, molecular dynamics (MD) simulations, immune simulations. On sequence retrieval, the epitopes were predicted and prioritized. The sequence of the finally designed vaccine was reached after a broad analysis of the antigenicity scores, serotype coverage, and population coverage. Human {beta}-defensin 3 has been added as an adjuvant to the core vaccine sequence that comprises 23 epitopes and linkers. Notably, the vaccine has the highest antigenicity (0.9319) and 97.35% population coverage worldwide. The molecular docking operations of the vaccine with toll-like receptor 2 (TLR2) and TLR4 showed promising interactions with lowest energies of -1240.5 kJ/mol (76 members) and -1393.3 kJ/mol (40 members), respectively. Molecular dynamics (MD) simulations were run up to 200 nanoseconds, and the complexes of the vaccine with TLR2 and TLR4 were found to be very stable and flexible. Moreover, in immune simulations, the vaccine evoked robust immune responses. These findings suggest that our vaccine outperforms any other Dengue vaccine developed to date. However, since this study was conducted through in silico methods, in vitro and in vivo validations are required to confirm the vaccine as a potential candidate for clinical trials. Author summaryWe developed a novel epitope-based tetravalent subunit vaccine against all dengue virus (DENV) serotypes using immunoinformatics. Our vaccine demonstrated high antigenicity (0.9319) and wide population coverage (97.35%). Molecular docking and dynamics simulations indicated strong interactions with immune receptors which is crucial for the vaccines activity inside human body. Moreover, immune simulations showed robust responses indicating proper immunity against DENV. Therefore, our vaccine offers a promising solution to dengue fever, pending further in vitro and in vivo validations for clinical trials. Notably, this is the first ever dengue vaccine with such high efficacy in terms of immunoinformatics and vaccinomic approaches.

bioinformatics↗