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Browsing by Author "Gregory, Casey L."

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    Classic Hoarding Cages Increase Gut Bacterial Abundance and Reduce the Individual Immune Response of Honey Bee (Apis mellifera) Workers
    Gregory, Casey L.; Fell, Richard D.; Belden, Lisa K.; Walke, Jenifer B. (Oxford University Press, 2022-03-01)
    Laboratory experiments have advanced our understanding of honey bee (Apis mellifera) responses to environmental factors, but removal from the hive environment may also impact physiology. To examine whether the laboratory environment alters the honey bee gut bacterial community and immune responses, we compared bacterial community structure (based on amplicon sequence variant relative abundance), total bacterial abundance, and immune enzyme (phenoloxidase and glucose oxidase) activity of cohort honey bee workers kept under laboratory and hive conditions. Workers housed in the laboratory showed differences in the relative abundance of their core gut taxa, an increase in total gut bacterial abundance, and reduced phenoloxidase activity, compared to bees housed in hives.
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    Effects of the antibiotic tetracycline on the honey bee gut microbiome
    Gregory, Casey L. (Virginia Tech, 2024-05-08)
    Host-associated microbial communities, also known as microbiomes, are essential to the health of their hosts, and disturbance of these communities can negatively impact host fitness. The honey bee gut microbiome is a relatively simple host-associated community that makes an excellent model system for studying microbiome stability. In addition, honey bees are essential agricultural pollinators, so factors that impact their health are important for food security. The presented research focused on the stability of the honey bee gut microbiome in response to disturbance from the antibiotic tetracycline. Tetracycline was chosen because it is the most commonly used antibiotic in beekeeping, and may have negative effects on bees through the disruption of their gut microbiomes. The first study presents a new fecal sampling method for studying the honey bee gut microbiome of individual bees over time. This method accurately represented bacterial community structure in the gut microbiome as determined with 16S rRNA gene amplicon sequencing, as fecal and whole gut samples did not differ significantly for individual bees. The fecal sampling technique was then used to examine changes to individual honey bee gut bacterial communities before and after tetracycline exposure. Minimal differences in gut community structure were detected prior to and five days after tetracycline treatment. However, there was variability in how individual gut microbiomes were affected by tetracycline treatment, highlighting the importance of intraspecific variation in response to disturbance. The second study investigated whether the timing of disturbance during a host's life impacts microbiome community stability. Newly emerged bees were treated with tetracycline, returned to their hive, and recollected 7 or 14 days later. The gut communities of the bees were then characterized using 16S rRNA gene amplicon sequencing. Gut microbiome structure of bees treated with tetracycline at emergence differed from controls both 7 and 14 days after emergence, with the antibiotic-treated bees having lower community richness overall. This study showed that early life disturbance of host-associated microbial communities can influence microbiome structure later in life. The final study describes the occurrence of antibiotic resistance genes (ARGs) in honey bee gut bacterial symbionts from hives across the US. Honey bee gut metagenomes were sampled from hives at 13 apiaries located in a transect from Virginia to Washington, and ARG presence was assessed across the sites. We also specifically quantified the abundances of two common tetracycline resistance genes (tet(B) and tet(M)) across apiaries. ARGs, both for antibiotics used in beekeeping and unrelated antibiotics, were detected in honey bee gut bacteria from all apiaries. Tetracycline resistance genes were the most common across all apiaries, and the abundance of two tetracycline resistance genes varied by apiary. Members of the honey bee gut microbiome contained different proportions of ARGs, but taxa within a single family contained similar proportions, possibly indicating phylogeny plays a role in ARG accumulation. In particular, Gilliamella and Frischella, both in the family Orbaceae, contained the highest percentages of ARGs. The results from this study suggest honey bee bacteria act as reservoirs of ARGs. Overall, the presented research contributes to the field of biology by highlighting the importance of intraspecific variation in host-associated microbial communities and presenting a new method for studying honey bee gut microbiome variation at the individual-level, showing that early life events in honey bees influence microbiome development, and suggesting that honey bee bacterial symbionts have adapted to deal with antibiotic disturbance through the accumulation of ARGs.
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    T3P-Promoted Synthesis of a Series of 2-Aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones and Their Activity against the Kinetoplastid Parasite Trypanosoma brucei
    Silverberg, Lee J.; Mal, Tapas K.; Pacheco, Carlos N.; Povelones, Megan L.; Malfara, Madeline F.; Lagalante, Anthony F.; Olsen, Mark A.; Yennawar, Hemant P.; Sobhi, Hany F.; Baney, Kayla R.; Bozeman, Robin L.; Eroh, Craig S.; Fleming, Michael J.; Garcia, Tracy L.; Gregory, Casey L.; Hahn, Julia E.; Hatter, Alyssa M.; Johns, Lexi L.; Klinger, Tianna L.; Li, Jennie J.; Menig, Andrew J.; Muench, Grace C.; Ramirez, Melissa E.; Reilly, Jordyn; Sacco, Nicole; Sheidy, Alexandra M.; Stoner, Marla M.; Thompson, Eric N.; Yazdani, Soroush F. (MDPI, 2021-10-09)
    A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate–good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites.