Photoautotrophic growth of Noctiluca scintillans with the endosymbiont Pedinomonas noctilucae

Abstract

Photosynthesis and respiration of a heterotrophic dinoflagellate Noctiluca scintillans that contained Pedinomonas noctilucae as an endosymbiont, were examined on cultures and natural populations in Manila Bay, Philippines, using a Clark-type oxygen electrode. The cultures isolated from the inner Gulf of Thailand were of two types: one required external supply of Dunaliella tertiolecta as food (feeding strains) and the other did not (non-feeding strains). The non-feeding strains grew photoautotrophically for generations, but they also fed on D. tertiolecta, indicating phagotrophy was facultative. Gross photosynthesis was at the same level in both types, but net photosynthesis was significantly higher in the non-feeding strains than the feeding ones. The difference was due to high respiration activity in the feeding strains. This was consistent with observations in the natural population of Manila Bay, where net photosynthesis was significantly higher in cells lacking food vacuoles than those with food vacuoles. The relationship of photosynthesis with irradiance was characterized by low intensity of light saturation and absence or weak photoinhibition, showing efficient utilization of a wide range of light intensities. P. noctilucae likely assures a supply of organic matter to the host, and facilitates survival of N. scintillans during shortages of food particles.

POPULATION DYNAMICS OF GREENNOCTILUCA SCINTILLANS(DINOPHYCEAE) ASSOCIATED WITH THE MONSOON CYCLE IN THE UPPER GULF OF THAILAND1

“…In contrast, green Noctiluca probably depends more on the organic matter produced by the symbiont during the NE monsoon than during the SW monsoon, thus maintaining a low growth rate (Furuya et al. 2006, Saito et al. 2006).…”

“…In fact, some clonal strains of green Noctiluca grow photoautotrophically without external food supply for generations (Furuya et al. 2006, Saito et al. 2006).…”

“…Green Noctiluca is also capable of phagotrophy and utilizes prey particles as food. The symbiont ensures the survival of green Noctiluca during shortage of food particles (Saito et al. 2006).…”

The Role of Photosynthesis and Food Uptake for the Growth of Marine Mixotrophic Dinoflagellates1

“…Yes/omnivorous Permanent, but the dinoflagellate can loose its symbionts Furuya et al 2006;Hansen et al 2004;Saito et al 2006;Sweeney 1971Sweeney , 1976 In all cases, the nucleus and/or other cell constituents of the symbiont are still present.…”

Locating Noctiluca miliaris in the Arabian Sea: An optical proxy approach

“…comm.) and the symbiotic relationships observed in the Arabian Sea and adjacent regions are likely to vary tremendously depending upon environmental conditions (Saito et al 2006;Sriwoon et al 2008). Considering these constraints we used an in situ approach to develop the fluorescence ratio proxy for N. miliaris, statistically determining the ratio from sample depths at which it numerically dominated the phytoplankton community.…”