Finding Some Good in an Invasive Species: Introduction and Assessment of a Novel CURE to Improve Experimental Design in Undergraduate Biology Classrooms.

Reports such as Vision and Change in Undergraduate Biology Education call for integration of course-based undergraduate research experiences (CUREs) into biology curricula and less emphasis on "cookbook" laboratories. CUREs, often characterized by a single open-ended research question, allow students to develop hypotheses, design experiments, and collaborate with peers. Conversely, "cookbook" labs incentivize task completion and have pre-determined experimental outcomes. While research comparing CUREs and "cookbook" labs is growing, there are fewer comparisons among CUREs. Here, we present a novel CURE built around an invasive grass, Bromus inermis. We evaluated this CURE's effectiveness in improving students' understanding of the Vision and Change competency relating to the application of the scientific process through development and testing of hypotheses. We did so by comparing changes in pre- and posttest scores on the Experimental Design Ability Test (EDAT) between Brome CURE students and students in a concurrent CURE, SEA-PHAGES. While students in both CUREs showed improvements at the end of the semester, Brome CURE students showed a greater increase in EDAT scores than did SEA-PHAGES CURE students. Additionally, Brome CURE students had significantly higher gains in 6 of the 10 EDAT criteria. We conclude that the Brome CURE is an effective ecological parallel to the SEA-PHAGES CURE and can help students gain a meaningful understanding of Vision and Change competencies. Journal of Microbiology & Biology Education.

Eukaryotic microbes, principally fungi and labyrinthulomycetes, dominate biomass on bathypelagic marine snow.

In the bathypelagic realm of the ocean, the role of marine snow as a carbon and energy source for the deep-sea biota and as a potential hotspot of microbial diversity and activity has not received adequate attention. Here, we collected bathypelagic marine snow by gentle gravity filtration of sea water onto 30 µm filters from ~1000 to 3900 m to investigate the relative distribution of eukaryotic microbes. Compared with sediment traps that select for fast-sinking particles, this method collects particles unbiased by settling velocity. While prokaryotes numerically exceeded eukaryotes on marine snow, eukaryotic microbes belonging to two very distant branches of the eukaryote tree, the fungi and the labyrinthulomycetes, dominated overall biomass. Being tolerant to cold temperature and high hydrostatic pressure, these saprotrophic organisms have the potential to significantly contribute to the degradation of organic matter in the deep sea. Our results demonstrate that the community composition on bathypelagic marine snow differs greatly from that in the ambient water leading to wide ecological niche separation between the two environments.

Dragon kings of the deep sea: marine particles deviate markedly from the common number-size spectrum.

Particles are the major vector for the transfer of carbon from the upper ocean to the deep sea. However, little is known about their abundance, composition and role at depths greater than 2000 m. We present the first number-size spectrum of bathy- and abyssopelagic particles to a depth of 5500 m based on surveys performed with a custom-made holographic microscope. The particle spectrum was unusual in that particles of several millimetres in length were almost 100 times more abundant than expected from the number spectrum of smaller particles, thereby meeting the definition of "dragon kings." Marine snow particles overwhelmingly contributed to the total particle volume (95-98%). Approximately 1/3 of the particles in the dragon-king size domain contained large amounts of transparent exopolymers with little ballast, which likely either make them neutrally buoyant or cause them to sink slowly. Dragon-king particles thus provide large volumes of unique microenvironments that may help to explain discrepancies in deep-sea biogeochemical budgets.

Nasal associated lymphoid tissue of the Syrian golden hamster expresses high levels of PrPC.

The key event in the pathogenesis of the transmissible spongiform encephalopathies is a template-dependent misfolding event where an infectious isoform of the prion protein (PrPSc) comes into contact with native prion protein (PrPC) and changes its conformation to PrPSc. In many extraneurally inoculated models of prion disease this PrPC misfolding event occurs in lymphoid tissues prior to neuroinvasion. The primary objective of this study was to compare levels of total PrPC in hamster lymphoid tissues involved in the early pathogenesis of prion disease. Lymphoid tissues were collected from golden Syrian hamsters and Western blot analysis was performed to quantify PrPC levels. PrPC immunohistochemistry (IHC) of paraffin embedded tissue sections was performed to identify PrPC distribution in tissues of the lymphoreticular system. Nasal associated lymphoid tissue contained the highest amount of total PrPC followed by Peyer's patches, mesenteric and submandibular lymph nodes, and spleen. The relative levels of PrPC expression in IHC processed tissue correlated strongly with the Western blot data, with high levels of PrPC corresponding with a higher percentage of PrPC positive B cell follicles. High levels of PrPC in lymphoid tissues closely associated with the nasal cavity could contribute to the relative increased efficiency of the nasal route of entry of prions, compared to other routes of infection.