DOI 10.3389/fmicb.2019.00808 Rimicaris exoculata is one of the most well-known and emblematic species of endemic vent fauna. Like many other species from these ecosystems, Rimicaris shrimps host important communities of chemosynthetic bacteria living in symbiosis with their host inside the cephalothorax and gut. For many of these symbiotic partners, the mode of transmission remains to be elucidated and the starting point of the symbiotic relationship is not yet defined, but could begin with the egg. In this study, we explored the proliferation of microbial communities on R. exoculata broods through embryonic development using a combination of NGS sequencing and microscopy approaches. Variations in abundance and diversity of egg microbial communities were analyzed in broods at different developmental stages and collected from mothers at two distinct vent fields on the Mid-Atlantic Ridge (TAG and Snake Pit). We also assessed the specificity of the egg microbiome by comparing communities developing on egg surfaces with those developing on the cuticle of pleopods, which are thought to be exposed to similar environmental conditions because the brood is held under the female’s abdomen. In terms of abundance, bacterial colonization clearly increases with both egg developmental stage and the position of the egg within the brood: those closest to the exterior having a higher bacterial coverage. Bacterial biomass increase also accompanies an increase of mineral precipitations and thus clearly relates to the degree of exposure to vent fluids. In terms of diversity, most bacterial lineages were found in all samples and were also those found in the cephalothorax of adults. However, significant variation occurs in the relative abundance of these lineages, most of this variation being explained by body surface (egg vs. pleopod), vent field, and developmental stage. The occurrence of symbiont-related lineages of Epsilonbacteraeota, Gammaproteobacteria, Zetaproteobacteria, and Mollicutes provide a basis for discussion on both the acquisition of symbionts and the potential roles of these bacterial communities during egg development.
hydrothermal, shrimp, microbial colonization, Alvinocarididae, egg development
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Publisher's official version | 19 | 4 Mo | ||
FIGURE S1 | X-Ray Spectrophotometric analysis (EDX) showing SEM analyzed areas of mineral crusts or mineral deposits for each sample with the corresponding spectrum.... | 5 | 817 Ko | ||
FIGURE S2 | Venn diagrams representing the numbers of shared OTUs across all samples. Affiliations of taxa representative of a body structure, vent field, or developmental stage are indicated. | 1 | 194 Ko | ||
FIGURE S3 | Alpha diversity measures of OTU number (Richness) and Inverse Simpson index (Evenness) compared (A) between eggs and pleopods, (B) between TAG and Snake Pit egg samples,... | 1 | 929 Ko | ||
FIGURE S4 | Mean relative abundances per categories of 16S rRNA gene sequence reads according to their classification (Silva 132 database). Groups are at the family level for the .... | 1 | 87 Ko | ||
FIGURE S5 | Ranked LDA scores of the differentially abundant bacterial taxa, with taxa with highest relative abundance at TAG in orange, and taxa with highest relative abundance at Snake Pit in blue.. | 1 | 1 Mo | ||
FIGURE S6 | Ranked LDA scores of the differentially abundant bacterial taxa, with taxa with highest relative abundance at early stage in yellow, at mid stage in brown and at late stage in purple for.. | 1 | 902 Ko | ||
FIGURE S7 | Additional FISH observations of Rimicaris exoculata eggs. Observations were performed on semi-thin sections (2 μm) stained with DAPI (blue) (A) Early stage egg hybridized with | 1 | 7 Mo | ||
TABLE S1 | List of samples used in this study. | - | 11 Ko | ||
TABLE S2 | List of FISH probes used in this study. | - | 9 Ko | ||
TABLE S3 | PERMANOVA analysis. | - | 10 Ko |
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