Uncovering key players for regulation of phytoplankton function and structure: lessons to be learned from algal virus-haptophyte coexistence

Informations

Funding country

Norway

Acronym

-

URL

-

Start date

1/1/2019

End date

12/31/2024

Budget

1,250,049 EUR

Fundings

Abstract

In the VirVar project we have conducted multiple infection experiments (from acute to persistent systems) describing the infection pattern in the different virus-host systems. Our results show surprisingly large differences in the traits, even when the same virus is infecting a different host species. In all experiments the host cells developed resistance toward the virus. Our comparative studies have shown that the resistant mechanism seems different between the systems. In three of the experiments the resistant cultures have developed some sort of co-existence with its virus, where the resistant host is growing seemingly normal, while viruses are produced. A manuscript describing these results is in progress. During the infection experiments we sampled for transcriptomics, which give insight to various gene regulation patterns including development of resistance in the different systems. All samples from the different infection experiments have been sequenced and preliminary analysed. The results show differences in viral genes that are expressed during the different stages of the infection. We have also started to investigate the response on infection in the host and how it defends itself towards the viral attack. Another important trait for a virus is the time it takes before it loses its infectivity (viral decay) in nature, where it is exposed to various environmental factors. Our results shows that the decay rate is different when measuring virus particles (VLP) or the ability to infect (infectious particles). The highest decay of the VLPs is during spring and summer. While the decay rate of infectious particles shows no differences between seasons. Differences in decay rate of infectious particles is only seen between the different virus systems. Those viruses being less infectious (persistent) had always lower decay compared to those that are more virulent (acute). We have started some simulations to see if we can sort out if there are different factors that affect the degradation of VLP and loss of infectivity. By novel high-resolution microscopy, we have shown large structural differences between our viruses and differences in their infection strategy. We are continuing these structural studies, which includes collaboration with Carmen San Martin (Centro Nacional de Biotecnología Madrid, Spania) as their institution is equipped with an excellent microscope platform. This work will be continued by a longer visit of our post doc next year to CNB. Sequencing of the host genomes Haptolina ericina is completed (JGI project nr DS 505156). The annotation of the He genome, to predict functions of the different genes, is started together with UiO. The two strains of Prymnesium kappa have been resent to JGI as there were problems with ploidy (mix haploid and diploid stages). New clones have been isolated and cultured and sent to JGI for sequencing. Public outreach: The importance of viruses in the ocean has been disseminated to the public through the INTPART project ConFect (322253). On Forskningsdagene I Bergen 2022 we informed students and stakeholders about viruses in the ocean on a boat trip between Bergen and Mongstad. In “passion for ocean summer camp 2022” our aim was to discuss what are viruses and explain why they are important for marine ecology and evolution for school children, including both a short lecture and a play about viruses. The school children were divided into 3 groups, fast growing algae (blue T shirts), slow growing algae (red T shirts) and marine viruses which could only infect “blue” algae. The aim of the game was for the red or blue algae to collect the most “nutrients” (which were small colourful plastic tokens) within 1 minute. However, blue algae were allowed to run, while red algae could only walk. If a virus caught a blue alga, they had to stop collecting nutrients immediately. The game was first played without viruses, and then with viruses. The students then had to count the number of tokens they had collected after 1 minute. Each time no viruses were included, the blue algae won, however once viruses were introduced the red algae had more tokens. Back in the classroom we asked the students to explain what they had learnt about algae and viruses from this game, with many understanding that the viruses allow different algae to live together. We also explained that many blue algae did not have time to pick up nutrients because they were focused on running and therefore “defending” against the virus, linking the game results to important ecological and evolution topics.