Biology subjects

Dvorak, M.

Publications and source records attributed to Dvorak, M..

4 recordsLinked to original sources

bioRxiv2024

Effects of parental care on skin microbial community composition in poison frogs

Parent-offspring interactions constitute the first contact of many newborns with their environment, priming community assembly of microbes through priority effects. Early exposure to microbes can have lasting influences on the assembly and functionality of the hosts microbiota, leaving a life-long imprint on host health and disease. Studies of the role played by parental care in microbial acquisition have primarily focused on humans and hosts with agricultural relevance. Anuran vertebrates offer the opportunity to examine microbial community composition across life stages as a function of parental investment. In this study, we investigate vertical transmission of microbiota during parental care in a poison frog (Family Dendrobatidae), where fathers transport their offspring piggyback-style from terrestrial clutches to aquatic nurseries. We found that substantial bacterial colonization of the embryo begins after hatching from the vitelline envelope, emphasizing its potential role as microbial barrier during early development. Using a laboratory cross-foster experiment, we demonstrated that poison frogs performing tadpole transport serve as a source of skin microbes for tadpoles on their back. To study how transport impacts the microbial skin communities of tadpoles in an ecologically relevant setting, we sampled frogs and tadpoles of sympatric species that do or do not exhibit tadpole transport in their natural habitat. We found more diverse microbial communities associated with tadpoles of transporting species compared to a non-transporting frog. However, we detected no difference in the degree of similarity between adult and tadpole skin microbiotas, based on whether the frog species exhibits transporting behavior or not. Using a field experiment, we confirmed that tadpole transport can result in the persistent colonization of tadpoles by isolated microbial taxa associated with the caregivers skin, albeit often at low prevalence. This is the first study to describe vertical transmission of skin microbes in anuran amphibians, showing that offspring transport may serve as a mechanism for transmission of parental skin microbes. Overall, these findings provide a foundation for further research on how vertical transmission in this order impacts host-associated microbiota and physiology.

microbiology↗

bioRxiv2024

Computational screening of T-muurolol for an alternative antibacterial solution against Staphylococcus aureus infections: A state-of-the-art phytochemical-based drug discovery approach

Staphylococcus aureus infections present a significant threat to the global healthcare system. The increasing resistance to existing antibiotics and their limited efficacy underscores the urgent need to identify new antibacterial agents with low toxicity to effectively combat various S. aureus infections. Hence, in this study, we have screened T-muurolol for possible interactions with several S. aureus-specific bacterial proteins to establish its potential as an alternative antibacterial agent. Based on binding affinity and interactions with amino acids T-muurolol was identified as a potential inhibitor of S. aureus lipase, dihydrofolate reductase, penicillin-binding protein 2a, D-Ala:D-Ala ligase, and RPP TetM, which indicates its potentiality against S. aureus and its multi-drug resistant strains. Also, T-muurolol exhibited good antioxidant and anti-inflammatory activity by showing strong binding interactions with FAD-dependent NAD(P)H oxidase, and cyclooxygenase-2. Consequently, MD simulation and recalculating binding free energies elucidated its binding interaction stability with targeted proteins. Furthermore, quantum chemical structure analysis based on density functional theory (DFT) depicted a higher EHOMO-LUMO energy gap with a lower chemical potential index, and moderate electrophilicity suggests its chemical hardness and stability and less polarizability and reactivity. Additionally, pharmacological parameters based on ADMET, Lipinskis rules, and bioactivity score validated it as a promising drug candidate with high activity toward ion channel modulators, nuclear receptor ligands, and enzyme inhibitors. In conclusion, the current findings suggest T-muurolol as a promising alternative antibacterial agent that might be a potential phytochemical-based drug against S. aureus. This study also suggests further clinical research before human application. Author SummaryStaphylococcus aureus significantly contributes to human mortality, with over 1 million deaths annually accredited to its infections. At the same time, antimicrobial resistance (AMR) is a critical public health issue, responsible for an estimated 1.27 million deaths globally in 2019. The overuse and abuse of antimicrobials in both human and veterinary medicine are primary drivers of AMR, complicating the treatment of infections and increasing the risks associated with surgeries and other medical events. Despite the availability of antimicrobials such as methicillin, vancomycin, daptomycin, and linezolid, the emergence of multidrug-resistant S. aureus poses a formidable challenge to effective treatment. Due to the limited efficacy and increasing resilience to current antibiotics, there is an urgent need to discover new and effective antibacterial drugs against S. aureus. Since time immemorial, phytochemicals have been valued for their rich biological properties and safety in treating bacterial infections. In this study, we have computationally investigated T-muurolol as a potential alternative antibacterial agent. Our molecular docking and simulation approaches provide insights into the interactions of T-muurolol as an inhibitor of S. aureus-specific bacterial proteins. Additionally, pharmacokinetic and quantum chemical structure analyses offer valuable information about T-muurolols potential as a drug candidate, supporting its further development as an antibacterial agent.

pharmacology and toxicology↗

bioRxiv2022

Achieving quantitative and accurate measurement of the human gut microbiome

Robust benchmarking studies have highlighted how measured relative microbial abundances can vary dramatically depending on how DNA is extracted, made into libraries, sequenced, and analyzed. To build upon prior research, we investigated how sample preservation and storage choices impact observed absolute microbial load and relative metagenomic and metatranscriptomic measurements. Specifically, we studied how two common stool preservatives (OMNIgene GUT OMR200 and Zymo DNA/RNA PowerShield) perform across a range of storage temperatures (-80{degrees}C, 23{degrees}C and 40{degrees}C). For immediately frozen samples with no preservatives, we observed a mean colonic load of [~]100 trillion (1.2 x 1014) prokaryotes across ten donors, revising the gut prokaryote:human cell ratio of [~]1:1 to [~]4:1. We found that both preservatives introduce significant bias in the metagenomics results; and, while OMNIgene results were robust to storage temperature, samples stored in Zymo preservative had further bias with increasing storage temperatures. In terms of measured composition, we observed a [~]1.9x and [~]1.5x difference in the metagenomic Bacteroidetes:Firmicutes ratio in OMNIgene and Zymo preservatives, respectively. Absolute abundance measurements revealed that these differences are driven by higher measured Bacteroidetes in OMNIgene-preserved samples and lower measured Firmicutes in Zymo-preserved samples. For metatranscriptomic measurements, we also found that both preservatives introduced bias, but that RNA likely degraded in samples stored in OMNIgene preservative at high temperature. In summary, we recommend the OMNIgene preservative for studies that include significant field components. For metatranscriptomics studies, we recommend kits rated for RNA preservation such as the Zymo kit; however, existing samples collected in non-RNA rated kits might also be viable for limited metatranscriptomic studies. This study demonstrates how sample collection and storage choices can affect measured microbiome research outcomes, makes additional concrete suggestions for sample handling best practices, and demonstrates the importance of including absolute abundance measurements in microbiome studies.

microbiology↗

bioRxiv2022

Crosstalk of Histone Modifications in the Healthy Human Immune System

Chromatin remodeling through post-translational modifications of histone tails (HPTM) is fundamental for regulation and maintenance of DNA-centered processes. Systems level understanding of coordination and interactions between HPTMs and their impact on the functional state of the immune cells remain unexplored due to the technical reasons. We leveraged large biologically heterogeneous data (>27 million cells), comprising of primary human immune cells profiled for 33 HPTMs and 4 histone variants at the single-cell level using high-dimensional mass cytometry (EpiTOF), to discover and map relations between HPTMs at the systems level. Briefly, we elucidated a comprehensive epigenetic network of HPTM interactions, discovered a novel subset of hematopoietic progenitors with distinct epigenetic profile, and revealed hitherto undescribed associations between a decrease in global methylations, modulation of one-carbon metabolism, and immune cell life span. Ultimately our work lays a foundation for future studies aimed at understanding complexity of HPTM interactions in immune response in infectious or autoimmune diseases, cancers, and vaccination.

immunology↗