Isolation and axenic culture of<i>Gymnodinium microadriaticum</i>from<i>Tridacna maxima</i>

Gymnodinoid dinoflagellate symbionts, commonly referred to as zooxanthellae, are widely distributed among marine invertebrates. It has been assumed that they represent only one species,Gymnodinium microadriaticum. The fatty acid composition of total lipids and galactolipids of zooxanthellae isolated from 8 species of corals, 3 species of clams and a foraminiferan have been analyzed and found to vary according to the host. For example, the content of eicosapentaenoic acid in clam zooxanthellae monogalactosyldiacylglycerol was less than 2%, whereas in the same lipid from coral zooxanthellae, the content ranged from 9 to 22%. Corresponding values for the acid in digalactosyl-diacylglycerol were 1-8% from clam zooxanthellae and 23-40% from coral zooxanthellae. Coral zooxanthellae monogalactosyldiacylglycerol contain higher levels of octadecatetraenoic acid than are found in digalactosyldiacylglycerol, whereas the reverse is true in clam zooxanthellae. The fatty acid composition of the lipids of an axenic culture of zooxanthellae isolated from the clamTridacna maxima are similar to those of cells freshly isolated from the host. The results suggest either that the host is capable of affecting the fatty acid metabolism of the symbiont or that different strains of zooxanthellae occur in corals and clams.

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“…Axenic cultures of dinoflagellates were grown using the conditions described by Deane and O'Brien (9).…”

Section: Methodsmentioning

confidence: 99%

Fatty acid composition of symbiotic zooxanthellae in relation to their hosts

Bishop

Kenrick

1980

Lipids

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“…Enrichment in the chloroplast GO category was expected since differences in photosynthesis (Bhagooli & Hidaka, 2003;Chen et al, 2012;Deane & O'Brien, 1978;Dubinsky et al, 1990;Stambler & Dubinsky, 2005) and in chloroplast content (Pasaribu et al, 2015) have been shown to occur between in hospite and cultured Symbiodiniaceae. However, in our analyses only one photosynthesis-related term was enriched in the down-regulated group and was not statistically significant (pval = .07).…”

Section: Differentially Expressed Genes In Hospitementioning

confidence: 99%

“…Conversely, inside the host where Symbiodiniaceae are confined by the symbiosome, the cells are coccoid, lack flagella (Trench, 1993), are larger (Pasaribu et al, 2015), have relatively smaller plastids (Pasaribu et al, 2015), and have thinner walls (Palincsar, Jones, & Palincsar, 1988;Pasaribu et al, 2015;Wakefield et al, 2000). In hospite, Symbiodiniaceae grow 1-2 orders of magnitude slower than in culture (Stambler, 2011;Wilkerson, Kobayashi, & Muscatine, 1988), and photosynthesis rates are also depressed (Bhagooli & Hidaka, 2003;Chen, Yeh, Wang, Li, & Chen, 2012;Deane & O'Brien, 1978). Finally, in hospite Symbiodiniaceae have different lipid profiles to those of cultured Symbiodiniaceae (Chen et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Symbiotic lifestyle triggers drastic changes in the gene expression of the algal endosymbiont Breviolum minutum (Symbiodiniaceae)

Maor-Landaw

Oppen

McFadden

2019

Ecology and Evolution

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Coral-dinoflagellate symbiosis underpins the evolutionary success of corals reefs. Successful exchange of molecules between the cnidarian host and the Symbiodiniaceae algae enables the mutualistic partnership. The algae translocate photosynthate to their host in exchange for nutrients and shelter. The photosynthate must traverse multiple membranes, most likely facilitated by transporters. Here, we compared gene expression profiles of cultured, free-living Breviolum minutum with those of the homologous symbionts freshly isolated from the sea anemone Exaiptasia diaphana, a widely used model for coral hosts. Additionally, we assessed expression levels of a list of candidate host transporters of interest in anemones with and without symbionts. Our transcriptome analyses highlight the distinctive nature of the two algal life stages, with many gene expression level changes correlating to the different morphologies, cell cycles, and metabolisms adopted in hospite versus free-living.Morphogenesis-related genes that likely underpin the metamorphosis process observed when symbionts enter a host cell were up-regulated. Conversely, many downregulated genes appear to be indicative of the protective and confined nature of the symbiosome. Our results emphasize the significance of transmembrane transport to the symbiosis, and in particular of ammonium and sugar transport. Further, we pinpoint and characterize candidate transporters-predicted to be localized variously to the algal plasma membrane, the host plasma membrane, and the symbiosome membrane-that likely serve pivotal roles in the interchange of material during symbiosis.Our study provides new insights that expand our understanding of the molecular exchanges that underpin the cnidarian-algal symbiotic relationship. K E Y W O R D S Breviolum minutum, Exaiptasia diaphana, free-living, in hospite, symbiosis, transporters S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Maor-Landaw K, van Oppen MJH, McFadden GI. Symbiotic lifestyle triggers drastic changes in the gene expression of the algal endosymbiont Breviolum minutum (Symbiodiniaceae).

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“…microadriatieum was isolated from T. maxima and cultured as described by Deane& O'Brien (1978). The organism was routinely grown in the ASPM medium of McLachlan (1964) at 24-26°C at a light intensity (at the culture surface) of 100 t~W cm -2 and was subcultured at intervals of 3 weeks.…”

Section: Growth Of G Microadriaticummentioning

confidence: 99%