Biology subjects

Tank, R. K. G.

Publications and source records attributed to Tank, R. K. G..

3 recordsLinked to original sources

bioRxiv2026

Cohabiting microbes can impact one another's mutation rates creating a mutational eco-evo feedback loop

Eco-evolutionary feedbacks are typically thought to require an ecological change driving Darwinian selection. However, ecology can drive other evolutionary mechanisms too. In many microbial species mutation rates are elevated at low population density, mediated by nutrient availability and reactive oxygen species (ROS). These findings from monoculture populations led us to hypothesise that the presence and density of a cohabiting species will also affect mutation rates. Using Escherichia coli as a focal species we explore the mutational effects on both parties of co-culture with either Enterococcus faecalis or Pseudomonas aeruginosa. These species co-occur in multiple clinical settings and have different abilities to degrade ROS. In both co-culture systems we find evidence that the presence of a stronger ROS degrader reduces mutation rates in the weaker ROS degrading species. At the same time increasing population density of the weaker ROS degrader increases mutation rates in the stronger ROS degrading species. Simultaneous mutation rate estimation in co-cultured species raises multiple experimental challenges addressed here. Despite these challenges, we find evidence for a novel form of eco-evo feedback in which the environment shapes the supply of mutational variation to the population. This in turn feeds back to alter the chance of evolutionary rescue for one species or another during a subsequent environmental change. Such effects potentially matter not only for our fundamental understanding of the interplay between ecology and evolution, but for the treatment of polymicrobial infections in which rates of resistance evolution may be altered by the cross-species mutational effects of cohabiting species.

evolutionary biology↗

bioRxiv2026

Fallopian Tube Organoid-Integrated Microfluidic Platform for Real-Time Imaging and Outflow Analysis

The fallopian tube is a dynamic, hormonally regulated epithelial conduit whose luminal microenvironment governs oocyte transport, fertilisation, early embryo development, and the initiation of gynaecological diseases including ectopic pregnancy, hydrosalpinx, and serous tubal intraepithelial carcinoma (STIC), yet existing models such as 2D monolayers, intact organoids, and static Transwell systems fail to recapitulate a polarised epithelium lining a perfused lumen under physiological fluid shear while preserving native organoid secretory function. We present a robust and accessible workflow integrating mechanically opened fallopian tube organoids into a custom-designed polydimethylsiloxane (PDMS) microfluidic device, in which organoid fragments form epithelial sheets and re-establish luminal-like architecture under controlled perfusion. The focus of this study is organoid integration and the characterisation of the resulting organoid-derived epithelium, rather than establishing chip cultures from individual cell lines. As this epithelium is built from expandable organoid stock rather than primary tissue, which typically survives only a few days in culture, the approach removes a major bottleneck to establishing organ-on-chip models, and we maintain viable cultures for up to 10 days. Epithelial sheets reproducibly covered more than 90% of the channel area by day 6 (n = 5 devices) and formed continuous ZO-1-positive tight junctions. The platform supports longitudinal brightfield and fluorescence microscopy at subcellular resolution, continuous collection of conditioned flow-through for ELISA, and quantitative analysis of cell coverage and health using CellProfiler software. We characterise the organoid-derived epithelium by benchmarking against tissue culture (TC) formats, comparing nuclear morphology on-chip with conventional well culture, and showing that the damage-associated cytokine interleukin-1 alpha (IL1 alpha) was undetectable in chip outflow, as in intact organoid secretions, indicating that cell health on-chip is comparable to that of intact organoids. Computational flow modelling characterises perfusion through the device and predicts how factors secreted by healthy epithelium and by tumour cells are distributed along the channel. The feasibility of tumour epithelium co culture was explored using OVCAR3 ovarian cancer spheroids as a proof of concept model of early tumour interaction with the tubal epithelium. Together, these results establish the technical feasibility of the platform and support its further development as an accessible system for studying reproductive health conditions affecting the fallopian tube, including tubal damage from infection, endometriosis, STIC lesions, and occlusion.

bioengineering↗

bioRxiv2026

Evolved resistance against the type 6 secretion system is toxin specific

Across ecosystems, microbes face attacks by competitors armed with lethal weapons, including toxin-injecting Type 6 Secretion Systems (T6SSs). This in turn selects for T6SS resistance, reducing the future effectiveness of T6SS weaponry in competition. However, we have only a limited understanding of how resistance to T6SS attacks evolves de novo. A key challenge is that T6SS-armed bacteria are highly diverse in the number and type of toxins they inject, spanning multiple distinct modes of action. Do functionally distinct T6SS toxins select for different mechanisms of resistance? To address this, we combine genomics, resistance assays and fluorescence microscopy, to characterise evolved resistances against common T6SS toxin classes across spatial scales. We discovered that amidase and lipase toxins select for mutations in distinct sets of genes, resulting in toxin-specific resistance phenotypes and fitness costs. We also discovered resistance trade-offs: lipase-evolved E. coli became less vulnerable to lipase membrane damage, at the cost of increased susceptibility to lysis by amidase toxins. Finally, using single-gene knockout mutants from the Keio collection we confirmed that specific genes not previously linked to T6SS resistance, including inner membrane transporters, osmo-sensing systems and stress response pathways, conferred resistance to specific toxins while generating sensitivity to others. The specificity of resistance, and associated trade-offs observed, are likely to constrain de novo evolution of resistance against T6SS attackers armed with multiple functionally distinct toxins, helping to explain why T6SS systems are so widespread in nature.

microbiology↗