title: Virus infection ofHaptolina ericinaandPhaeocystis pouchetiiimplicates evolutionary conservation of programmed cell death induction in marine haptophyte-virus interactions.
abstract: The mechanisms by which phytoplankton cope with stressors in the marine environment are neither fully characterized nor understood. As viruses are the most abundant entities in the global ocean and represent a strong top-down regulator of phytoplankton abundance and diversity, we sought to characterize the cellular response of two marine haptophytes to virus infection in order to gain more knowledge about the nature and diversity of microalgal responses to this chronic biotic stressor. We infected laboratory cultures of the haptophytesHaptolina ericinaandPhaeocystis pouchetiiwith CeV-01B or PpV-01B dsDNA viruses, respectively, and assessed the extent to which host cellular responses resemble programmed cell death (PCD) through the activation of diagnostic molecular and biochemical markers. Pronounced DNA fragmentation and activation of cysteine aspartate-specific proteases (caspases) were only detected in virus-infected cultures of these phytoplankton. Inhibition of host caspase activity by addition of the pan-caspase inhibitor z-VAD-fmk did not impair virus production in either host-virus system, differentiating it from theEmiliania huxleyi-Coccolithovirus model of haptophyte-virus interactions. Nonetheless, our findings point to a general conservation of PCD-like activation during virus infection in ecologically diverse haptophytes, with the subtle heterogeneity of cell death biochemical responses possibly exerting differential regulation on phytoplankton abundance and diversity.
authors.affiliation: Uni Research As , Thormøhlensgt 49B, N-5006 Bergen , Norway ; Department of Biology , University of Bergen , Thormøhlensgt 53A, N-5006 Bergen , Norway.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Ray
authors.affiliation: Institute of Marine and Coastal Sciences, Rutgers University , 71 Dudley Road, New Brunswick, NJ 08901 , USA.
authors.forename: Liti
authors.initials: L
authors.lastname: Haramaty
authors.affiliation: Department of Biology , University of Bergen , Thormøhlensgt 53A, N-5006 Bergen , Norway.
authors.forename: Runar
authors.initials: R
authors.lastname: Thyrhaug
authors.affiliation: Marine Chemistry and Geochemistry , Woods Hole Oceanographic Institution , Woods Hole, MA 02543 , USA.
authors.forename: Helen F
authors.initials: HF
authors.lastname: Fredricks
authors.affiliation: Marine Chemistry and Geochemistry , Woods Hole Oceanographic Institution , Woods Hole, MA 02543 , USA.
authors.forename: Benjamin A S
authors.initials: BA
authors.lastname: Van Mooy
authors.affiliation: Uni Research As , Thormøhlensgt 49B, N-5006 Bergen , Norway ; Department of Biology , University of Bergen , Thormøhlensgt 53A, N-5006 Bergen , Norway.
authors.forename: Aud
authors.initials: A
authors.lastname: Larsen
authors.affiliation: Institute of Marine and Coastal Sciences, Rutgers University , 71 Dudley Road, New Brunswick, NJ 08901 , USA.
authors.forename: Kay D
authors.initials: KD
authors.lastname: Bidle
authors.affiliation: Department of Biology , University of Bergen , Thormøhlensgt 53A, N-5006 Bergen , Norway.
authors.forename: Ruth-Anne
authors.initials: RA
authors.lastname: Sandaa
keywords: DNA fragmentation; IETD; Phycodnaviridae; caspase; haptophyte; z-VAD-fmk