Speaker Background: Dr. Irene Newton, PhD, specializes in mechanisms of symbiosis; specifically, the molecular mechanisms of host-microbe symbiotic interactions. She obtained her PhD from Harvard University and conducted postdoctoral research at Tufts University. She is currently an associate professor at Indiana University.
Seminar Summary: Apis mellifera, the western honey bee, develop from egg to pupae within their colony. Throughout the development, they come into contact with different microbiota (Gilliamella, Snodgrassella, Bombella, Lactobacillus) through nectar, pollen, and interaction with other bees. These interactions can establish the gut microbiota, help protect against potential pathogens, and aid in nutrient acquisition. Using honey bees as models, Newton aimed to study how society, genetics, and behavior affect the microbial community.
First, Newton examined the queen microbiome during and after development. She sampled both queens and workers at various time points of development to determine the microbiota and if the queens and workers microbiota were similar, indicating microbial exchange. In her findings, Newton explained that the worker and queen microbiota are distinct, and do not share microbial composition. The queens were also variable in the microbial composition and titer.
Community composition of the workers contain the “core” microbes. However, the queens had a larger composition of microbes, especially Bombella. Bombella is often referred to as the queen microbiota since it is not found commonly in the worker digestive tract. Newton attributed the differences in microbiota in queens vs. workers to physiological differences, since queens have larger ovaries and live for years, while workers typically live for 3-4 weeks. Also, queens are fed royal jelly, a specific diet that rears queen bees. Newton hypothesized that the royal jelly is pre-inoculated with Bombella apis, developing a distinct queen microbiota.
Next, Newton aimed to better understand the origin of B. apis, and its relationship with royal jelly. Through phylogenetic analysis, her team determined that B. apis is closely related to Saccharibacter, a flower-associated organism. Through sequence composition, synteny, phylogenetic methods, and functional analysis, she questioned if there were horizontally transferred regions between flower-associated Saccharibacter and B. apis. Results revealed that HGT1 is conserved across B. apis honeybee strains, and its function is currently unknown. HGT4 and HGT5 are also conserved and are metabolic gene regions that aid in immune defenses and the metabolism of sugars. Overall, B.apis acquired multiple metabolic and defense gene regions that protect the honey bee from other pathogens, and these genes contain signatures of honey bee association as they are distinct from Saccharibacter, a flower-associated organism.
Personal Review: I found Dr. Newton’s presentation very interesting and impactful. I broadly have experience with bumble bee microbiota, but honey bees are very different, and so is their microbiota. As Dr. Newton mentioned in her presentation, microbiome research is almost exclusive to workers and not queens. Even in bumble bee research, studies exhaustively use workers, but queen health homeostasis is much less understood. Dr. Newton was not only able to include queen microbiota samples, but additionally, relate and compare it back to workers. This study is very impactful to the field and combining the wet lab data collection and the dry lab data analysis is impressive, and it makes me excited to find out what her team is doing next. Dr. Irene Newton is a scientist I would love to connect with in the future, and I am fortunate to hear about her research through the Vanderbilt Microbiome Innovation Center.
Note: Seminar was presented on Wednesday, October 14th, 2020, and was viewed on
Vanderbilt Microbiome Innovation Center channel on YouTube.
https://www.youtube.com/watch?v=nBDIjsgSzZ4&t=601s
