Effects of Myostatin b Knockout on Offspring Body Length and Skeleton in Yellow Catfish (Pelteobagrus fulvidraco)

Simple Summary Myostatin is a negative regulator of muscle growth and development, and mutational inactivation of this gene increases muscle mass. Knockout of the mstnb gene in Pelteobagrus fulvidraco did not increase muscle mass, although our previous study of the mstna gene did. Instead, it reduced the body size and growth performance of Pelteobagrus fulvidraco. Through the present study, we found that the mutant Pelteobagrus fulvidraco had a reduction in the number of vertebrae, the length, and the intervertebral distance in Pelteobagrus fulvidraco, and these changes may be the underlying cause of the shorter body length in mutant Pelteobagrus fulvidraco. Histological comparison of the same sites in the mstn mutant and wild groups of Pelteobagrus fulvidraco also revealed that the number and density of osteocytes were greater in mstnb knockout Pelteobagrus fulvidraco than in wild-type Pelteobagrus fulvidraco.Abstract Based on obtaining mstnb gene knockout in Pelteobagrus fulvidraco, a study on the effect of the mstn gene on skeletal morphology and growth was performed by comparing the number and length of the vertebrae of mutant and wild-type fish in a sibling group of P. fulvidraco, combined with the differences in cells at the level of vertebral skeletal tissue. It was found that mstnb gene knockdown resulted in a reduction in the number of vertebrae, the length, and the intervertebral distance in P. fulvidraco, and these changes may be the underlying cause of the shorter body length in mutant P. fulvidraco. Further, histological comparison of the same sites in the mstn mutant and wild groups of P. fulvidraco also revealed that the number and density of osteocytes were greater in mstnb knockout P. fulvidraco than in wild-type P. fulvidraco. Our results demonstrated that when using genome editing technology to breed new lines, the effects of knockout need to be analyzed comprehensively and may have some unexpected effects due to insufficient study of the function of certain genes.