World Aquaculture 2023

May 29 - June 1, 2023

Darwin, Northern Territory, Australia


Linyan Zhou, You Wu


Background: Tilapia is the second most prolific species grown in aquaculture after carp, and is widely grown in more than 100 countries. Myostatin (MSTN) has been proved to be a negative regulator of skeletal muscle growth. Mutation of MSTN gene resulted in significant increase in both body size and muscle mass in vertebrates, mostly with a species-specific effect.

Materials and methods: In this study, the qRT-PCR, FISH and IF were used for gene expression detection and cellular localization. The mstnb homozygous mutants were obtained by CRISPR/Cas 9 gene editing technology. The feeding trial was carried out to investigate the growth performance of mstnb-/- tilapia and wild-type (WT) tilapia at 5 and 7 months after hatching (mah). The relative quantitative of muscle fibers was analyzed by image J software.

Results: Mstnb is abundant in the basement membrane of skeletal muscle, while mstna is dominantly expressed in the brain. Compared with the WT fish, the mstnb-/- mutants showed a typical double-muscle phenotype with increased muscle mass, sticking out between head and dorsal fin, from 5 mah. Morphological observation revealed an excessive proliferation of white muscle fibers at 7 mah. The average body weights, body heights and body widths of the mstnb-/- fish were 49.45%, 32.74 % and 37.21% higher than those of the mstnb+/+ fish at 5 mah. The growth performance parameters of the mstnb-/- fish, including weight gain rate (1.99 times), condition factor (1.77 times) and specific growth rate (1.23 times), were significantly higher than the mstnb+/+ fish under laboratory conditions at 5 mah. In addition, the parameters of WGR, CF, SGR and FE were significantly increased in mstnb-/- Nile tilapia than those of mstnb+/+ Nile tilapia and GIFT tilapia for a 90-day feeding trial under the wild natural environment.