Research Overview
Endosymbiosis in cnidaria-dinoflagellate association plays a critical role in regulating productivity of corals and related marine ecosystems. Endosymbiosis is an obligatory and mutualistic association occurring at cellular level, where a cell (the “symbiont”, usually plant cells or bacteria) resides inside another cell of other species (the “host cell”, usually animal or plant cells). Environmental changes, including temperature, photo-irradiation and pollution, have devastating effects on the coral-dinoflagellate endosymbiosis and result in the expulsion of symbiont from the host cells which caused coral bleaching. This eventually leads to the death of corals and destruction of marine ecological systems. As a consequence, the urgency and interest to understand how the endosymbiosis is regulated in coral-dinoflagellate association have also resulted in intensive investigations during past decades.
Cellular endosymbiosis with Symbiodinium spp. (the symbiont) in corals (the host) is thought to be initiated by a three-step process: (i) the recognition between the host gastrodermal cell and the symbiont, then (ii) the host gastrodermal cell phagocytoses the symbiont and finally (iii) the association between the host cell and its included symbiont matures to establish an obligatory and mutualistic interaction. However, the detailed mechanisms of each step remain unclear notwithstanding decades of research. This slowness in research progress is attributed to the lack of working models that can be examined at the cellular, molecular and organism levels for both the host cell and its included symbiont. With the availability of advanced biological and biophysical technologies, plus well developed facilities and experience in coral culture, we propose to investigate several objectives to learn how the endosymbiosis are regulated during endosymbiosis establishment.