Researchers at the Institute of Oceanology of the Chinese Academy of Sciences overcame major hurdles in genome-edited aquaculture by establishing a viable population of Pacific abalones carrying targeted mutations. The team produced approximately 100 juvenile Pacific abalones (Haliotis discus hannai) with edits to Hdh-tyr1, a tyrosinase gene involved in shell formation, with the largest individuals reaching about 3 centimeters in shell length.
The main challenge was not the genome editing itself, but rearing the edited larvae through metamorphosis. Early attempts failed when protist outbreaks killed entire larval batches within days in conventional culture systems. The researchers solved this by rearing each larva individually in what they called "single apartments" and combining this with an optimized metamorphosis induction protocol that achieved larval survival rates above 90%.
After metamorphosis, the team identified three benthic diatom species that served as high-quality feed for newly metamorphosed abalones and promoted rapid growth. They also developed a simplified DNA extraction method for efficient genotyping of very small juveniles.
"The individual-level verification provided an early 'identity verification' of the edited animals," said Yu Yanan, first author of the study published in Aquaculture. "It also helped confirm that mutated larvae had developed into mutated juveniles."
The integrated workflow combined genome editing system construction, larval and juvenile rearing, metamorphosis induction, and individual organism genotyping. Professor Huan Pin, a corresponding author, stated that the G0 genome-edited population was generated using this workflow. The researchers described the work as a step toward completing the technical process for genome-editing-based breeding in mollusks.