Multiple microalgal partners in symbiosis with the acantharian Acanthochiasma sp. (Radiolaria)

Type Article
Date 2012-12
Language English
Author(s) Decelle Johan1, 2, Siano Raffaele3, Probert Ian4, Poirier C1, 2, Not Fabrice1, 2
Affiliation(s) 1 : Univ Paris 06, UMR 7144, Biol Stn, F-29680 Roscoff, France.
2 : CNRS, Biol Stn, UMR 7144, F-29680 Roscoff, France.
3 : IFREMER, Ctr Brest, DYNECO Pelagos, F-29280 Plouzane, France.
4 : Univ Paris 06, FR 2424, Biol Stn, F-29680 Roscoff, France.
Source Symbiosis (0334-5114) (Springer), 2012-12 , Vol. 58 , N. 1-3 , P. 233-244
DOI 10.1007/s13199-012-0195-x
WOS© Times Cited 15
Keyword(s) Photosymbiosis, Radiolaria, Acantharia, Protists, Microalgae, Plankton
Abstract Acantharia (Radiolaria) are widespread and abundant heterotrophic marine protists, some of which can host endosymbiotic eukaryotic microalgae. Although this photosymbiotic association was first described at the end of the 19th century, the diversity of the symbiotic microalgae remains poorly characterized. Here, we examined the identity of the microalgae associated with the acantharian species Acanthochiasma sp. by sequencing partial 18S and internal transcribed spacer (ITS) ribosomal DNA genes from cultured symbionts and directly from isolated holobiont specimens. Single Acanthochiasma cells contained multiple symbiotic partners, including distantly related dinoflagellates (Heterocapsa sp., Pelagodinium sp., Azadinium sp. and Scrippsiella sp.) as well as a haptophyte (Chrysochromulina sp.). This original association of multiple symbiotic microalgae within a single host cell raises questions about the specificity and functioning of the relationship. These microalgae exhibit the common ecological feature of being abundant and widely distributed in coastal and oceanic waters, some occasionally forming extensive blooms. Some of the microalgal genera found in association
with Acanthochiasma (i.e. Pelagodinium and Chrysochromulina) are known to occur in symbiosis with other heterotrophic protists such as Foraminifera and other Radiolaria, whereas Heterocapsa, Scrippsiella and Azadinium have never previously been reported to be involved in putative symbiotic relationships. The unusual association unveiled in this study contributes to our understanding of the ecological and evolutionary significance of photosymbiosis in Acantharia and also provides new insights into the nature of such partnerships in the planktonic realm.
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