Student Application of Immunology Concepts and Mechanisms Through Test Based Learning on Canvas

Application of immunological concepts is a major challenge for students, especially during a pandemic when most students are learning remotely. Many students memorize the details, but often fail to critically process the information to form a comprehensive understanding of how the immune system works. To address this concern, we developed a “test-based learning” approach to engage students and reinforce important concepts. We converted our immunology lecture-based cases to a quiz format that was presented through our Learning Management Software (Canvas). This approach provides students the opportunity to remotely apply the information presented in lecture either independently or in a small group format through Teams. These cases engaged students to discuss the important aspects of the case and the immunological mechanisms involved. If students struggled, Faculty Members were available via Teams video chat or email to answer questions. We realized that this approach allowed for increased student participation, more active learning, and increased questions to faculty members in comparison to asking questions during lecture. A final advantage of this method is that faculty were able to quickly assess if students mastered key concepts by analyzing students’ scores. If faculty identified deficiencies, there was ample time to address misconceptions before an exam. This approach can be easily modified and used in any course that uses Learning Management Software (e.g. Canvas or Blackboard). Furthermore, this approach is not only applicable to medical education, but could be used at both the undergraduate and graduate levels.

Dependence of the cyanobacterium Prochlorococcus on hydrogen peroxide scavenging microbes for growth at the ocean's surface

The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect) biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co-existing species.