Symbiotic bacteria associated with a bobtail squid reproductive system are detectable in the environment, and stable in the host and developing eggs

Abstract

Female Hawaiian bobtail squid, Euprymna scolopes, have an accessory nidamental gland (ANG) housing a bacterial consortium that is hypothesized to be environmentally transmitted and to function in the protection of eggs from fouling and infection. The composition, stability, and variability of the ANG and egg jelly coat (JC) communities were characterized and compared to the bacterial community composition of the surrounding environment using Illumina sequencing and transmission electron microscopy. The ANG bacterial community was conserved throughout hosts collected from the wild and was not affected by maintaining animals in the laboratory. The core symbiotic community was composed of Alphaproteobacteria and Opitutae (a class of Verrucomicrobia). Operational taxonomic units representing 94.5% of the average ANG abundance were found in either the seawater or sediment, which is consistent with the hypothesis of environmental transmission between generations. The bacterial composition of the JC was stable during development and mirrored that of the ANG. Bacterial communities from individual egg clutches also grouped with the ANG of the female that produced them. Collectively, these data suggest a conserved role of the ANG/JC community in host reproduction. Future directions will focus on determining the function of this symbiotic community, and how it may change during ANG development.

Achieving a multi-strain symbiosis: strain behavior and infection dynamics

“…In the field of microbial symbiosis, significant interest focuses on community-level structure and on distinguishing the contributions of different species within complex hostassociated microbiomes [1][2][3][4][5]. Recently, an awareness of the importance of strain-level differences occurring within a colonizing bacterial species in such communities has emerged [1,[6][7][8].…”

Reproductive System Symbiotic Bacteria Are Conserved between Two Distinct Populations of Euprymna scolopes from Oahu, Hawaii

“…The bobtail squid, Euprymna scolopes , is endemic to the Hawaiian archipelago and relies on the well-studied light organ symbiont Vibrio fischeri to avoid predation ( 1 ). In addition to this symbiosis, adult females also harbor a complex bacterial consortium in their reproductive system ( 2 , 3 ). The accessory nidamental gland (ANG) is conserved throughout many species of squid, cuttlefish, and bobtail squid ( 4 ) and was first described over a century ago ( 5 ).…”

Reports from a Healthy Community: the 7th Conference on Beneficial Microbes

“…Not just host-encoded factors but also resident microbes play important roles in shaping host-microbe interactions, as illustrated by the talk from Spencer Nyholm (University of Connecticut, Storrs, CT), "The Hawaiian Bobtail Squid as a Model for Studying Defensive Symbioses and Development." In studying the microbiome of the accessory nidamental gland (ANG), a reproductive organ in female cephalopods, including the bobtail squid (Euprymna scolopes), he showed that the ANG is packed with a diverse consortium of bacteria (20,21). The ANG sits adjacent to the oviduct, and as eggs pass by the gland, bacteria are deposited into the developing jelly coat layer.…”