The functional role of photosynthesis-related genes in non-photosynthetic symbionts of corals

2021 Fiscal Year Annual Research Report

• Project/Area Number: 21F21081
• Allocation Type: Single-year Grants
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: HUSNIK Filip 沖縄科学技術大学院大学, 進化・細胞・共生の生物学ユニット, 准教授 (30886130)
• Co-Investigator(Kenkyū-buntansha): ALVES DOS SANTOS MARIA 沖縄科学技術大学院大学, 進化・細胞・共生の生物学ユニット, 外国人特別研究員
• Project Period (FY): 2021-09-28 – 2024-03-31
• Keywords: Symbiosis / Microbiome / Evolution / Genomics / Ecology / Apicomplexa / Dinoflagellate / Coral

Outline of Annual Research Achievements

We collected coral colonies and performed DNA extraction. In order to identify apicomplexans associated with corals (order Corallicolida, also called corallicolids), PCR amplification was conducted using specific primers for the 18S rRNA region and Sanger sequencing. Preliminary results indicated that most corals from Japan and other parts of the Indo-Pacific Ocean associated with the same generalist corallicolid species. Still, some corals samples were associated with a distinct corallicolid lineage.

Additionally, library preparation and MiSeq sequecing was used to evaluate the diversity of microbes associated with corals, using 16S rRNA (bacteria), 18S rRNA (Eukaryotes), and ITS2 rRNA (diniflagellates of the family Symbiodiniaceae) primers. We analyzed the data with bioinformatics following published pipelines. Preliminary results showed that corals associated with Symbiodiniaceae of the genera Cladocopium, Durisdinium and Symbiodinium. Moreover, corals from the Atlantic and the Indo-Pacific oceans have a different Symbiodiniaceae composition. In relation to bacteria, the mutualistic genus Endozoicomonas was the most common symbiont of corals. Some samples were associated with Vibrio spp., which are opportunistic pathogens. Samples from different regions on the Indo-Pacific Ocean analyzed so far had a different bacterial composition.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

Most part of the molecular work (DNA extraction, PCR amplification, library preparation and sequencing) and bioinformatic analyses were already performed. Part of the bioinformatic analyses of the 16S and 18S MiSeq data is still in progress.

Strategy for Future Research Activity

The next step of the project is to finish the bioinformatic analyses. Following, I will focus in the second part of the project (single-cell 'omics' and microscopy).

Research Products

• [Presentation] Global diversity of coral endosymbionts (2022)
  • Author(s): Maria E. A. Santos, James D. Reimer, Masaru Mizuyama, Hiroki Kise, Wee H. Boo, Akira Iguchi, ‘Ale’alani Dudoit, Robert Toonen, Marcelo V. Kitahara, Filip Husnik
  • Organizer: “Oceans - and the impact of humans and climate change” - OIST-Tohoku U. 2nd Joint Workshop on Marine Science