Light, C. J. | Search bioRxiv

bioRxiv2021

Keeping students connected and engaged in a wet-lab research experience during a time of social distancing via mobile devices and video conferencing software

Two major COVID-19 pandemic challenges presented for in-person instruction included adhering to social distancing guidelines and accommodating remote learners who were temporarily isolated or permanently participating from afar. At Binghamton University, our First-year Research Immersion (FRI) program was challenged with providing students with a wet lab course-based undergraduate research experience (CURE), an intense hands-on experience that emphasized student teamwork, lab protocol development, iteration, troubleshooting and other elements of the process of science that could not be replicated in a fully remote environment. We developed an innovative technology approach to maximize all students connection to the lab research experience utilizing dedicated mobile devices (iPod Touch) and video conferencing software (Zoom) to synchronously connect remote learners to in-person learners, peer mentors and instructors in our FRI research labs. In this way, despite limited lab capacities and fluctuating remote learning populations, we were able to connect remote learners to their peers and mentors in real-time and give them responsibilities that allowed them to be engaged and feel like meaningful participants in the research process. Although our students reported a preference for in-person labs, they noted this hybrid model was better than other traditionally employed remote-learning lab options. We believe lessons learned here can be applied to improve access to research in all situations and allow us to be prepared for other catastrophic disruptions to the educational system.

scientific communication and education↗

bioRxiv2020

PQS-Induced Outer Membrane Vesicles Enhance Biofilm Dispersion in Pseudomonas aeruginosa

Bacterial biofilms are major contributors to chronic infections in humans. Because they are recalcitrant to conventional therapy, they present a particularly difficult treatment challenge. Identifying factors involved in biofilm development can help uncover novel targets and guide the development of anti-biofilm strategies. Pseudomonas aeruginosa causes surgical site, burn wound, and hospital acquired infections, and is also associated with aggressive biofilm formation in the lungs of cystic fibrosis patients. A potent but poorly understood contributor to P. aeruginosa virulence is the ability to produce outer membrane vesicles (OMVs). OMV trafficking has been associated with cell-to-cell communication, virulence factor delivery, and the transfer of antibiotic resistance genes. Because OMVs have almost exclusively been studied using planktonic cultures, little is known about their biogenesis and function in biofilms. Our group has shown that the Pseudomonas Quinolone Signal (PQS) induces OMV formation in P. aeruginosa, and in other species, through a biophysical mechanism that is also active in biofilms. Here, we demonstrate that PQS-induced OMV production is highly dynamic during biofilm development. Interestingly, PQS and OMV synthesis are significantly elevated during dispersion, compared to attachment and maturation stages. PQS biosynthetic and receptor mutant biofilms were significantly impaired in their ability to disperse, but this phenotype could be rescued by genetic complementation or exogenous addition of PQS. Finally, we show that purified OMVs can actively degrade extracellular protein, lipid, and DNA. We therefore propose that enhanced production of PQS-induced OMVs during biofilm dispersion facilitates cell escape by coordinating the controlled degradation of biofilm matrix components. ImportanceTreatments that manipulate biofilm dispersion hold the potential to convert chronic drug-tolerant biofilm infections from protected sessile communities into released populations that are orders-of-magnitude more susceptible to antimicrobial treatment. However, dispersed cells often exhibit increased acute virulence and dissemination phenotypes. A thorough understanding of the dispersion process is therefore critical before this promising strategy can be effectively employed. PQS has been implicated in early biofilm development, but we hypothesized that its function as an OMV inducer may contribute at multiple stages. Here, we demonstrate that PQS and OMVs are differentially produced during Pseudomonas aeruginosa biofilm development and that effective biofilm dispersion is dependent on production of PQS-induced OMVs, which likely act as delivery vehicles for matrix degrading enzymes. These findings lay the groundwork for understanding the roles of OMVs in biofilm development and suggest a model to explain the controlled matrix degradation that accompanies biofilm dispersion in many species.

microbiology↗