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Published on: August 12, 2019
INTERSTRAIN VARIABILITY IN PHYSIOLOGY AND GENETICS OF HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE) FROM THE WEST COAST OF
Kerri A Fredrickson1, Suzanne L Strom1, Ryan Crim1
1Shannon Point Marine Center, Western Washington University, Anacortes, Washington 98221, USACollege of Earth, Ocean, and Environment, University of Delaware, Lewes, Delaware 19958, USA.
Intraspecific variability in Heterosigma akashiwo (Hada) contributes to bloom success. Distinct ecotypes were identified through biochemical, physiological, and genetic analyses, aiding in strain tracking and prediction.
Area of Science:
- Marine biology
- Phycology
- Ecotoxicology
Background:
- Harmful algal bloom (HAB) species often exhibit high intraspecific variability, influencing competitive success.
- Heterosigma akashiwo (Hada) is an ichthyotoxic raphidophyte forming blooms globally.
- Four H. akashiwo strains were isolated from fish-killing blooms in Puget Sound.
Purpose of the Study:
- To characterize distinct ecotypes of H. akashiwo based on biochemical, physiological, and genetic traits.
- To investigate the relationship between intraspecific variability and ecological success.
- To assess the utility of molecular tools for identifying and tracking H. akashiwo strains.
Main Methods:
- Isolation and cultivation of four H. akashiwo strains.
- Biochemical and physiological assessments (cell size, growth rates, photosynthesis, salinity tolerance, amino acid utilization).
- Toxicity assays against Strombidinopsis acuminatum.
- Molecular analyses (rDNA sequencing, chloroplast genome sequencing).
Main Results:
- Distinct ecotypes were identified with variations in cell size, growth rates, salinity tolerance, amino acid use, and toxicity.
- Chloroplast genome sequencing revealed genetic differences correlating with ecotype variations, while rDNA sequences were identical.
- Strain 07A showed higher photosynthesis and growth rates; strains 06A/06B utilized specific amino acids; strain 07B was non-toxic.
Conclusions:
- Intraspecific variability in H. akashiwo contributes to diverse ecotypes with differing ecological strategies.
- Chloroplast gene signatures can differentiate H. akashiwo ecotypes.
- Molecular tools show promise for identifying, tracking, and predicting HAB strains and ecotypes.
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