The genetic diversity of Mesodinium and associated cryptophytes

• Published in: Frontiers in Microbiology
• Main Authors: Johnson, Matthew D., Beaudoin, David J., Laza-Martinez, Aitor, Dyhrman, Sonya T., Fensin, Elizabeth, Lin, Senjie, Merculief, Aaron, Nagai, Satoshi, Pompeu, Mayza, Setälä, Outi, Stoecker, Diane K.
• Other Authors: Tvärminne Zoological Station
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media 2017
• Subjects: Mesodinium; Teleaulax; cryptophytes; ciliates; acquired phototrophy; mixotrophy; red tides; ciliate genetic diversity; CILIATE MYRIONECTA-RUBRA; COLUMBIA RIVER ESTUARY; SP-NOV CRYPTOPHYCEAE; GENUS CRYPTOMONAS CRYPTOPHYCEAE; RECURRENT RED-TIDES; NORTHERN BALTIC SEA; PHOTOTROPHIC CILIATE; PRIMARY PRODUCTIVITY; MOLECULAR PHYLOGENY; CHESAPEAKE BAY; 1184 Genetics; developmental biology; physiology; Bering Sea
• Online Access: http://hdl.handle.net/10138/175280

Ciliates from the genus Mesodinium are globally distributed in marine and freshwater ecosystems and may possess either heterotrophic or mixotrophic nutritional modes. Members of the Mesodinium major/rubrum species complex photosynthesize by sequestering and maintaining organelles from cryptophyte prey, and under certain conditions form periodic or recurrent blooms (= red tides). Here, we present an analysis of the genetic diversity of Mesodinium and cryptophyte populations from 10 environmental samples (eight globally dispersed habitats including five Mesodinium blooms), using group-specific primers for Mesodinium partial 18S, ITS, and partial 28S rRNA genes as well as cryptophyte large subunit RuBisCO genes (rbcL). In addition, 22 new cryptophyte and four new M, rubrum cultures were used to extract DNA and sequence rbcL and 18S-ITS-28S genes, respectively, in order to provide a stronger phylogenetic context for our environmental sequences. Bloom samples were analyzed from coastal Brazil, Chile, two Northeastern locations in the United States, and the Pribilof Islands within the Bering Sea. Additionally, samples were also analyzed from the Baltic and Barents Seas and coastal California under non-bloom conditions. Most blooms were dominated by a single Mesodinium genotype, with coastal Brazil and Chile blooms composed of M. major and the Eastern USA blooms dominated by M. rubrum variant B. Sequences from all four blooms were dominated by Teleaulax amphioxeia-like cryptophytes. Non bloom communities revealed more diverse assemblages of Mesodiniurn spp., including heterotrophic species and the mixotrophic Mesodinium Chamaeleon. Similarly, cryptophyte diversity was also higher in non-bloom samples. Our results confirm that Mesodinium blooms may be caused by M. major, as well as multiple variants of M, rubrum, and further implicate I amphioxeia as the key cryptophyte species linked to these phenomena in temperate and subtropical regions. Peer reviewed