Geographically conserved microbiomes of four temperate water tunicates

Abstract

Tunicates are useful models for exploring microbiomes because they have an innate immune system resembling that of chordates. Automated ribosomal RNA intergenic spacer analysis and High-Throughput Sequencing were used to compare the tunic microbiomes of Ciona robusta (formerly Ciona intestinalis type A), Ciona savignyi, Botrylloides leachi and Botryllus schlosseri sampled from three distinct locations with limited genetic connectivity. Bacterial phylotype profiles were conserved within each species, and there were no detectable differences between tunic and tunic + cuticle subsamples from an individual. Bacterial operational taxonomic unit (OTU) diversity was lowest for C. savignyi (320 ± 190 OTUs) and highest for B. schlosseri (1260 ± 190 OTUs). Each species had a distinct set of bacterial OTUs (pseudo-F = 3.0, p > 0.001), with the exception of B. leachi and B. schlosseri from one sampling location (t = 1.2, p = 0.09). Of note were OTUs assigned to Alphaproteobacteria from C. robusta plus Phyllobacteriaceae and Endozoicomonas from C. savignyi. These OTUs contributed 51, 22 and 10% of sequence reads, respectively, and are related to known bacterial symbionts. The within-species conservation of core OTUs across three distinct and co-occurring populations of tunicates provides compelling evidence that these tunicates foster defined microbiomes.

Uncovering the core microbiome and distributions of palmerolide inSynoicum adareanumacross the Anvers Island archipelago, Antarctica

“…The overall trend across ascidian microbiome studies to date suggests that there is a high degree of both geographical as well as host-species level specificity of microbiome composition (e.g. 35, 36, 39). The same appears to be true of S. adareanum.…”

“…Other solitary ascidians, including Herdmania momus had a core of 17 OTUs (40), while two Ciona species ranged from 8-9 OTUs. Temperate colonial ascidians Botryliodes leachi and Botryllus schlosseri ranged from 10-11 members in their core microbiomes (39). Also, an extensive survey of 10 different ascidian microbiomes (representing both solitary and colonial forms) conducted on the Great Barrier Reef reported core memberships ranging from 2 to 35 OTUs (35), while the numbers of individuals surveyed in each case were only 2-3.…”

The Microbiome of the Worldwide Invasive Ascidian Didemnum vexillum

“…Among marine invertebrates, most research to date has been performed on corals and sponges (e.g., Webster and Taylor, 2012;Blackall et al, 2015;Hill and Sacristán-Soriano, 2017;Pita et al, 2018;Kellogg, 2019;van Oppen and Blackall, 2019). Comparatively, ascidians have attracted less attention, despite harboring a highly diverse assemblage of symbionts in their tunics that can fulfill diverse functions (Erwin et al, 2014;Cahill et al, 2016;Dou and Dong, 2019). These symbionts have been investigated mostly from the point of view of their potential role in the production of ascidian secondary metabolites (Schmidt, 2014;Tianero et al, 2015;Chen et al, 2018;Dou and Dong, 2019).…”

Endozoicomonas genomes reveal functional adaptation and plasticity in bacterial strains symbiotically associated with diverse marine hosts

“…for review14). These bacteria associate with a wide variety of marine hosts, including corals1516171819, and other cnidarians2021, sponges2223, gorgonians242526, molluscs2728, worms29, fish3031, and tunicates3233. Despite these associations with numerous hosts in oceans worldwide, the functional role of Endozoicomonas remains unclear.…”