Biology subjects

Newton, I. L. G.

Publications and source records attributed to Newton, I. L. G..

3 recordsLinked to original sources

bioRxiv2018

Genomic signatures of honey bee association in an acetic acid symbiont

Honey bee queens are central to the success and productivity of their colonies; queens are the only reproductive members of the colony, and therefore queen longevity and fecundity can directly impact overall colony health. Recent declines in the health of the honey bee have startled researchers and lay people alike as honey bees are agricultures most important pollinator. Honey bees are important pollinators of many major crops and add billions of dollars annually to the US economy through their services. One factor that may influence queen and colony health is the microbial community. Although honey bee worker guts have a characteristic community of bee-specific microbes, the honey bee queen digestive tracts are colonized by a few bacteria, notably an acetic acid bacterium not seen in worker guts: Bombella apis. This bacterium is related to flower-associated microbes such as Saccharibacter floricola and other species in the genus Saccharibacter, and initial phylogenetic analyses placed it as sister to these environmental bacteria. We used comparative genomics of multiple honey bee-associated strains and the nectar-associated Saccharibacter to identify genomic changes associated with the ecological transition to bee association. We identified several genomic differences in the honey bee-associated strains, including a complete CRISPR/Cas system. Many of the changes we note here are predicted to confer upon them the ability to survive in royal jelly and defend themselves against mobile elements, including phages. Our results are a first step towards identifying potential benefits provided by the honey bee queen microbiota to the colonys matriarch.

genomics↗

bioRxiv2018

Differential carbohydrate utilization and organic acid production by honey bee symbionts

The honey bee worker gut is host to a community of bacteria that primarily comprises 8-10 bacterial species. Collectively, these microbes break down and ferment saccharides present in the hosts diet. The model of metabolism for these gut symbionts is rooted in previous analyses of genomes, metagenomes, and metatranscriptomes of this environment. Importantly, there is a correlation between the composition of the gut microbiome and weight gain in the honey bee, suggesting that bacterial production of organic acids might contribute to the observed phenomenon. Here we identify potential metabolic contributions of symbionts within the honey bee gut. We show significant variation in the metabolic capabilities of these microbes, highlighting the fact that although the microbiota appears simple and consistent based on 16S rRNA gene profiling, strains are highly variable in their ability to use specific carbohydrates and produce organic acids. Finally, we confirm that the honey bee core microbes, especially a clade of {gamma}-proteobacteria (i.e. Gilliamella), are highly active in vivo, expressing key enzymatic genes critical for utilizing plant-derived molecules and producing organic acids. These results suggest that Gilliamella, and other core taxa, may contribute significantly to weight gain in the honey bee, specifically through the production of organic acids.

microbiology↗

bioRxiv2017

Evolutionary genetics of cytoplasmic incompatibility genes cifA and cifB in prophage WO of Wolbachia

The bacterial endosymbiont Wolbachia manipulates arthropod reproduction to facilitate its maternal spread through populations. The most common manipulation is cytoplasmic incompatibility (CI): Wolbachia-infected males produce modified sperm that cause embryonic mortality, unless rescued by eggs harboring the same Wolbachia. The genes underlying CI, cifA and cifB, were recently identified in the eukaryotic association module of Wolbachias prophage WO. Here, we use transcriptomic and genomic approaches to address three important evolutionary facets of these genes. First, we assess whether or not cifA and cifB comprise a classic toxin-antitoxin operon, and show they do not form an operon in strain wMel. They coevolve but exhibit strikingly distinct expression across host development. Second, we provide new domain and functional predictions across homologs within Wolbachia, and we show amino acid sequences vary substantially across the genus. Lastly, we investigate conservation of cifA and cifB and find degradation and loss of the genes is common in strains that no longer induce CI. Taken together, we find no evidence for the operon hypothesis in wMel, provide functional annotations that broaden the potential mechanisms of CI induction, illuminate recurrent erosion of cifA and cifB in non-CI strains, and advance an understanding of the most widespread form of reproductive parasitism.

evolutionary biology↗