| Autor: |
Gómez, Fernando, Simão, Taiz L.L., Utz, Laura R.P., Lopes, Rubens M. |
| Zdroj: |
Phycologia; March 2016, Vol. 55 Issue: 3 p265-273, 9p |
| Abstrakt: |
Abstract:The consortium between the colonial stramenopile Solenicola setigeraand the centric chain-forming diatom Leptocylindrus mediterraneusis cosmopolitan throughout the world ocean yet rarely abundant. However, the nature of the association remains enigmatic. A mutualistic symbiosis requires a live diatom host, but the frustule of L. mediterraneusis apparently empty, lacking protoplasm and plastids. The parasitism requires free-living host cells to be infected, but there is no evidence of populations of the free-living diatom. During experiments attempting to culture the heterotrophic S. setigera, we successfully obtained a strain of the host diatom. In the small-subunit (SSU) rDNA phylogeny, L. mediterraneuswas closely related to Dactyliosolen blavyanusand to a new sequence of Dactyliosolensp. while distantly related to the genus Leptocylindrus. We proposed the reinstatement of L. mediterraneusin the genus Dactyliosolenas D. mediterraneus. Even under optimal growth conditions, the frustule was nearly empty with reduced protoplasm concentrated in the middle. When compared with congeneric species, D. mediterraneusshowed a double-layered structure that acts as substrate for Solenicola. The free-living diatom lacked the convex walls that D. mediterraneusshowed as host of Solenicola. The diatom in consortium with Solenicolamaintained the photosynthetic machinery to eventually proliferate as a free-living organism. The ecological and morphological observations suggested that the diatom was successfully adapted to the mutualistic symbiosis with Solenicola. We discarded a parasitic relationship in this exceptional example of symbiosis. |
| Databáze: |
Supplemental Index |
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