| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1194-1 | ||||
Resumo:Throughout the former decades, the scientific community has come to the agreement that microbiota acquisition seems to impact greatly on metazoan’s physiology, playing a central role on its development. Chagas Disease vector Rhodnius prolixus literature points the bacteria Rhodococcus rhodnii, identified in the early XX century, as the vector’s natural symbiont. Despite high performance sequencing applied to 16S identification on R. prolixus gut samples has shown a diverse microbial composition, R. rhodnii still remains as an important member of the host’s microbial consortia. Based on these grounds, our aim falls on assess R. prolixus neonates’ physiological responses after its first met with R. rhodnii. In order to generate Aposymbiotic insects, we kept R. prolixus eggs under aseptic conditions after prior decontamination with ethanol and hypochlorite, which completely extinguish R. prolixus from eggs. Following exposure to adult’s faeces restore nymph’s microbiota, that reaches around a million R. rhodnii cells per gut at day 8 post feeding. Intending to assess whether R. prolixus input determine its colonisation dynamics on the host, R. rhodnii was offered on amounts varying from a hundred to ten million cells per insect. Bacterial growth dynamics on all experimental groups tends to a common point reached at day 4, accounting for a million bacteria per insect’s gut. Colonisation decay similarly among the groups over time, suggesting the existence of a fine-tuning mechanism that limits bacterial growth. An Illumina RNA-seq performed on first instar nymphs over a 12 days period after feeding had shown a global modulation of over 130 immune-related genes, including effectors such as Antimicrobial Peptides and Lysozymes. In order to investigate whether the presence of the symbiont impacts on host immune status, gene expression of immune-related components was assessed by qPCR on nymphs exposed or not to adult’s faeces. It came to our knowledge that both Lysozyme A and Defensin C are upregulated whether in the presence or absence R. rhodnii. Despite there were none cultured bacteria found on non-exposed nymphs, 16S mRNA levels had shown the presence of yet-to-be cultured bacteria, possibly not transmitted by faeces. Even so, the number of bacteria on non-exposed nymphs did not increase over time, contrasting with the 30-fold increased found on exposed nymphs at day 4 post feeding. Together, our data suggests that the global immune response is not necessarily conditioned to microbiota expansion on the gut, nor to the presence of the symbiont. Finally, a 16S high performance sequencing on first instar nymphs’ whole gut and adults anterior midguts had shown a major microbial composition restricted to five taxa: three of them belonging to Enterobacterales order, and one belonging to Pseudomonas genera. Further studies might indicate if those are found on non-exposed-to-feaces nymphs. The fifth taxa, R. rhodnii, has a major importance of adults microbiota composition, accounting for 20 to 50% of the each sample’s consortia, contrasting with its mild presence on nymphs. This could indicate a possible selection of microbiota composition along the insect’s development, but further studies are needed to unveil this hypothesis. Altogether, our data indicates that there are unveiled aspects related to R. prolixus gut microbiota composition, transmission, and its possible interaction with physioloyical features from the host, such as immunity. Palavras-chave: microbiota, neonate, symbiont, immunity Agência de fomento:INCT-EM, CNPq, CAPES e FAPERJ | |||||