Date of Award
Master of Science in Biological and Environmental Sciences (MSBES)
Gregarines are a diverse group of apicomplexan parasites that inhabit the intestines, coeloms and reproductive vesicles of marine, freshwater, and terrestrial invertebrates. They have been known to dominate soil communities and show high infection rates within their hosts. Despite this, little information is available about the impact of infection on the gut microbiome of their hosts. Tunicates are a known host of gregarines and several species already have preliminary research focusing on microbial sampling and even screening for bioactive metabolites with pharmaceutical potential. The solitary ascidian Ciona intestinalis emerged as a model organism for studying host–microbe interactions taking place in the gut, however, the additional layer of analyzing for gregarine infected and uninfected microbial gut communities remains unexplored. By identifying the host’s microflora through high throughput sequencing of a DNA barcode from the bacterial 16S rRNA and measuring metabolite concentrations with NMR spectroscopy, we can begin to understand how gregarines influence the environment they occupy within the host.
Sequencing revealed similar bacterial communities between infected and uninfected C. intestinalis, with the same dominant phyla making up nearly equal structure of the relative abundances. Alpha and beta diversity statistics supported this observation, with infected tunicates exhibiting slightly greater diversity, though the difference was not significant. Preliminary NMR spectroscopy data showed the majority of metabolite concentrations did not differ between infected and uninfected ascidian guts. Of the significantly up regulated metabolites 76 compounds were found in the infected intestine and 23 compounds in the uninfected, some carbohydrates, fatty acids and metabolites related to osmoregulatory and oxidative stress revealing increased concentrations within infected samples. Clustering of cultured metabolites within the infected samples suggests similar a similar metabolic relationship and potential dysbiosis, however random error could be contributing to these conclusions as there was low overall concentrations and extreme variance in the data. Our data indicate that gregarine infection of Lankesteria ascidiae has little impact on the tunicate gut microbiome and metabolome of Ciona intestinalis, though slight variations in microbial community and metabolites will provide a preliminary library of information to build from. Further exploration of host-microbiome/metabolome interactions comparing presence and absence of infection by utilizing transcriptomics, liquid-chromatography mass spectrometry, and physiological measures will aid in gaining a better understanding of the chemical impact gregarines have on the gut and further help to create and in vitro culturing system.
Spencer, Evelyn Anna, "INVESTIGATION INTO THE IMPACT OF PARASITIC APICOMPLEXANS ON THE GUT MICROBIOME OF MARINE TUNICATE CIONA INTESTINALIS" (2022). Open Access Master's Theses. Paper 2151.