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1. A cryopreservation method to recover laboratory- and field-derived bacterial communities from mosquito larval habitats

   https://doi.org/10.1371/journal.pntd.0011234  

   Zhao, Serena Y.; Hughes, Grant L.; Coon, Kerri L. (April 2023, PLOS Neglected Tropical Diseases)

   Bartholomay, Lyric C. (Ed.)

   Mosquitoes develop in a wide range of aquatic habitats containing highly diverse and variable bacterial communities that shape both larval and adult traits, including the capacity of adult females of some mosquito species to transmit disease-causing organisms to humans. However, while most mosquito studies control for host genotype and environmental conditions, the impact of microbiota variation on phenotypic outcomes of mosquitoes is often unaccounted for. The inability to conduct reproducible intra- and inter-laboratory studies of mosquito-microbiota interactions has also greatly limited our ability to identify microbial targets for mosquito-borne disease control. Here, we developed an approach to isolate and cryopreserve bacterial communities derived from lab and field-based larval rearing environments of the yellow fever mosquito Aedes aegypti –a primary vector of dengue, Zika, and chikungunya viruses. We then validated the use of our approach to generate experimental microcosms colonized by standardized lab- and field-derived bacterial communities. Our results overall reveal minimal effects of cryopreservation on the recovery of both lab- and field-derived bacteria when directly compared with isolation from non-cryopreserved fresh material. Our results also reveal improved reproducibility of bacterial communities in replicate microcosms generated using cryopreserved stocks over fresh material. Communities in replicate microcosms further captured the majority of total bacterial diversity present in both lab- and field-based larval environments, although the relative richness of recovered taxa as compared to non-recovered taxa was substantially lower in microcosms containing field-derived bacteria. Altogether, these results provide a critical next step toward the standardization of mosquito studies to include larval rearing environments colonized by defined microbial communities. They also lay the foundation for long-term studies of mosquito-microbe interactions and the identification and manipulation of taxa with potential to reduce mosquito vectorial capacity. 

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2. pH selects for distinct N2O-reducing microbiomes in tropical soil microcosms

   https://doi.org/10.1093/ismeco/ycae070  

   Sun, Yanchen; Yin, Yongchao; He, Guang; Cha, Gyuhyon; Ayala-del-Río, Héctor L; González, Grizelle; Konstantinidis, Konstantinos T; Löffler, Frank E (January 2024, ISME Communications)

   Abstract Nitrous oxide (N2O), a greenhouse gas with ozone destruction potential, is mitigated by the microbial reduction to dinitrogen catalyzed by N2O reductase (NosZ). Bacteria with NosZ activity have been studied at circumneutral pH but the microbiology of low pH N2O reduction has remained elusive. Acidic (pH < 5) tropical forest soils were collected in the Luquillo Experimental Forest in Puerto Rico, and microcosms maintained with low (0.02 mM) and high (2 mM) N2O assessed N2O reduction at pH 4.5 and 7.3. All microcosms consumed N2O, with lag times of up to 7 months observed in microcosms with 2 mM N2O. Comparative metagenome analysis revealed that Rhodocyclaceae dominated in circumneutral microcosms under both N2O feeding regimes. At pH 4.5, Peptococcaceae dominated in high-N2O, and Hyphomicrobiaceae in low-N2O microcosms. Seventeen high-quality metagenome-assembled genomes (MAGs) recovered from the N2O-reducing microcosms harbored nos operons, with all eight MAGs derived from acidic microcosms carrying the Clade II type nosZ and lacking nitrite reductase genes (nirS/K). Five of the eight MAGs recovered from pH 4.5 microcosms represent novel taxa indicating an unexplored N2O-reducing diversity exists in acidic tropical soils. A survey of pH 3.5–5.7 soil metagenome datasets revealed that nosZ genes commonly occur, suggesting broad distribution of N2O reduction potential in acidic soils. 

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3. Invasibility of a North American soil ecosystem to amphibian-killing fungal pathogens

   https://doi.org/10.1098/rspb.2023.2658  

   McGrath-Blaser, Sarah E; McGathey, Natalie; Pardon, Allison; Hartmann, Arik M; Longo, Ana V (April 2024, Proceedings of the Royal Society B: Biological Sciences)

   North American salamanders are threatened by intercontinental spread of chytridiomycosis, a deadly disease caused by the fungal pathogenBatrachochytrium salamandrivorans(Bsal). To predict potential dispersal ofBsalspores to salamander habitats, we evaluated the capacity of soil microbial communities to resist invasion. We determined the degree of habitat invasibility using soils from five locations throughout the Great Smoky Mountains National Park, a region with a high abundance of susceptible hosts. Our experimental design consisted of replicate soil microcosms exposed to different propagule pressures of the non-native pathogen,Bsal, and an introduced but endemic pathogen,B. dendrobatidis(Bd). To compare growth and competitive interactions, we used quantitative PCR, live/dead cell viability assays, and full-length 16S rRNA sequencing. We found that soil microcosms with intact bacterial communities inhibited bothBsalandBdgrowth, but inhibitory capacity diminished with increased propagule pressure.Bsalshowed greater persistence thanBd. Linear discriminant analysis (LDA) identified the family Burkolderiaceae as increasing in relative abundance with the decline of both pathogens. Although our findings provide evidence of environmental filtering in soils, such barriers weakened in response to pathogen type and propagule pressure, showing that habitats vary their invasibility based on properties of their local microbial communities. 

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4. Extending Engineering Learning Beyond Field Trips

   Muller, Alexandria; Connolly, Tarah; Skinner, Ron; Harlow, Danielle (October 2020, Science and children)

   null (Ed.)

   We worked with local K–6 teachers to develop lesson plans that would connect a 50-minute engineering design challenge, completed during a field trip, to the students’ classroom learning. The result was a model for designing pre-visit classroom activities that develop students’ familiarity with phenomena, tools, and processes that will be used during the field trip and post-visit classroom activities that provide students with opportunities to reflect on some of their field trip experiences. While the field trip activity alone is an exciting and productive learning opportunity, students who complete the full set of classroom and field trip activities participate in a richer experience that engages them in more of the practices of science and engineering and more fully develops the disciplinary core ideas related to engineering and physical science. Each Engineering Exploration module includes four activities: an engineering design activity completed during a field trip to an interactive science museum, accompanied by two preactivities and one post activity done in students’ classroom and facilitated by their elementary school teacher. While each classroom activity was designed to take no more than 50 minutes, many teachers found it valuable to extend each lesson to allow for deeper discussion and engagement with the activities. The classroom experiences presented here are associated with a field trip program in which students iteratively design a craft out of paper and tape that will hover above a “fire” (upward moving column of air) while carrying a “sensor” (washer). The classroom activities surrounding this field trip help students develop conceptual understandings of forces to navigate the engineering design challenge. 

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5. Impact of changing physical learning space on GTA and student behaviors

   https://doi.org/10.1119/perc.2020.pr.Doty  

   Doty, Constance M.; Wan, Tong; Geraets, Ashley A.; Nix, Christopher A.; Saitta, Erin K.; Chini, Jacquelyn J. (January 2020, Physics Education Research Conference 2020)

   null (Ed.)

   We investigated how changing the physical classroom impacted graduate teaching assistant (GTA) and student behaviors in tutorial sections of an introductory algebra-based physics sequence. Using a modified version of the Laboratory Observation Protocol for Undergraduate STEM (LOPUS), we conducted 35 observations over two semesters for seven GTAs who taught in different styles of classrooms (i.e., active learning classrooms and traditional classrooms). We found that both GTAs and students changed behaviors in response to a change from an active learning classroom to a traditional classroom. GTAs were found to be less interactive with student groups and to lecture at the whiteboard more frequently. Correspondingly, student behaviors changed as students asked fewer questions during one-on-one interactions. These findings suggest that the instructional capacity framework, which typically focuses on interactions between instructors, students and instructional materials, should also include interactions with the learning space. We suggest administrators and departments consider the impact of changing to a traditional classroom when implementing student-centered instruction and emphasize how to use classroom space in GTA professional development. 

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