The characteristics of host lipid body biogenesis during coral-dinoflagellate endosymbiosis

Hung-Kai Chen; Sabrina L Rosset; Li-Hsueh Wang; Chii-Shiarng Chen

doi:10.7717/peerj.11652

The characteristics of host lipid body biogenesis during coral-dinoflagellate endosymbiosis

PeerJ. 2021 Jun 23:9:e11652. doi: 10.7717/peerj.11652. eCollection 2021.

Authors

Hung-Kai Chen¹, Sabrina L Rosset¹, Li-Hsueh Wang^{1

2}, Chii-Shiarng Chen^{1

2

3}

Affiliations

¹ National Museum of Marine Biology and Aquarium, Pingtung, Taiwan.
² Graduate Institute of Marine Biology, National Dong-Hwa University, Pingtung, Taiwan.
³ Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan.

Abstract

Intracellular lipid body (LB) biogenesis depends on the symbiosis between coral hosts and their Symbiodinaceae. Therefore, understanding the mechanism(s) behind LB biosynthesis in corals can portentially elucide the drivers of cellular regulation during endosymbiosis. This study assessed LB formation in the gastrodermal tissue layer of the hermatypic coral Euphyllia glabrescens. Diel rhythmicity in LB size and distribution was observed; solar irradiation onset at sunrise initiated an increase in LB formation, which continued throughout the day and peaked after sunset at 18:00. The LBs migrated from the area near the mesoglea to the gastrodermal cell border near the coelenteron. Micro-LB biogenesis occurred in the endoplasmic reticulum (ER) of the host gastrodermal cells. A transcriptomic analysis of genes related to lipogenesis indicated that binding immunoglobulin protein (BiP) plays a key role in metabolic signaling pathways. The diel rhythmicity of LB biogenesis was correlated with ER-localized BiP expression. BiP expression peaked during the period with the largest increase in LB formation, thereby indicating that the chaperoning reaction of abnormal protein folding inside the host ER is likely involved in LB biosynthesis. These findings suggest that the host ER, central to LB formation, potentially facilitates the regulation of endosymbiosis between coral hosts and Symbiodiniaceae.

Keywords: Coral; Diel cycle; Endoplasmic reticulum; Lipid bodies; Symbiosis.

Grants and funding

This work was supported by a grant from the Ministry of Science and Technology (MOST) of Taiwan (formerly the National Science Council [NSC]; NSC 101-2311-B-291-002-MY3 and MOST 108-2311-B-291-001 to CSC) and by intramural funding from NMMBA (99200311). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.