title: Effects of the bacterial algicide IRI-160AA on cellular morphology of harmful dinoflagellates.
abstract: The algicide, IRI-160AA, induces mortality in dinoflagellates but not other species of algae, suggesting that a shared characteristic or feature renders this class of phytoplankton vulnerable to the algicide. In contrast to other eukaryotic species, the genome of dinoflagellates is stabilized by high concentrations of divalent cations and transition metals and contains large amounts of DNA with unusual base modifications. These distinctions set dinoflagellates apart from other phytoplankton and suggest that the nucleus may be a dinoflagellate-specific target for IRI-160AA. In this study, morphological and ultrastructural changes in three dinoflagellate species, Prorocentrum minimum, Karlodinium veneficum and Gyrodinium instriatum, were evaluated after short-term exposure to IRI-160AA using super resolution structured illumination microscopy (SR-SIM) and transmission electron microscopy (TEM). Exposure to the algicide resulted in cytoplasmic membrane blebbing, differing chloroplast morphologies, nuclear expansion, and chromosome expulsion and/or destabilization. TEM analysis showed that chromosomes of algicide-treated K. veneficum appeared electron dense with fibrous protrusions. In algicide-treated P. minimum and G. instriatum, chromosome decompaction occurred, while for P. minimum, nuclear expulsion was also observed for several cells. Results of this investigation demonstrate that exposure to the algicide destabilizes dinoflagellate chromosomes, although it was not clear if the nucleus was the primary target of the algicide or if the observed effects on chromosomal structure were due to downstream impacts. In all cases, changes in cellular morphology and ultrastructure were observed within two hours, suggesting that the algicide may be an effective and rapid approach to mitigate dinoflagellate blooms.
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA.
authors.forename: Kaytee L
authors.initials: KL
authors.lastname: Pokrzywinski
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Tilney
authors.affiliation: Biomaging Center, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA.
authors.forename: Shannon
authors.initials: S
authors.lastname: Modla
authors.affiliation: Biomaging Center, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA.
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Caplan
authors.affiliation: Biomaging Center, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Ross
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Warner
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA. Electronic address: kcoyne@udel.edu.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Coyne
mesh_terms: D002467:Cell Nucleus / Q000187:drug effects* / Q000648:ultrastructure; D004141:Dinoflagellida / Q000187:drug effects* / Q000648:ultrastructure; D006540:Herbicides / Q000494:pharmacology*; D046529:Microscopy, Electron, Transmission; D010839:Phytoplankton / Q000187:drug effects* / Q000648:ultrastructure; D013045:Species Specificity
chemical_list: D006540:Herbicides
keywords: Algicide; Cell cycle inhibition; Chromosome decompaction; Dinoflagellate; Morphology; Nucleus