斑马鱼nos2a基因的生长调控作用

鱼类的生长调控一直是水产领域研究的热点。为了在斑马鱼中探索诱导型一氧化氮合酶（Nos2）在生长调控中的作用，我们通过CRISPR/Cas9基因编辑技术，首次构建了可稳定遗传的nos2a缺失型（nos2a-/-）斑马鱼家系。通过监测其生长过程发现，nos2a-/- 斑马鱼的整体生长趋势较nos2a正常型（nos2a+/+）斑马鱼偏低，且nos2a-/-成鱼的体型显著小于同期的nos2a+/+ 斑马鱼（P <0.01）：nos2a+/+成鱼体长（29.53 ± 0.60） mm，nos2a-/-成鱼体长（26.34 ± 0.69） mm；nos2a+/+成鱼体质量（512.8 ± 30.75） mg，nos2a-/-成鱼体质量（394.4 ± 16.91） mg。而在肌纤维密度（P =0.718）及躯椎骨的横截面积上（P =0.548）两者没有显著差异。qPCR检测发现，出膜8天时，nos2a-/- 斑马鱼的生长激素基因gh1的mRNA水平（P <0.01）及类胰岛素生长因子基因igf1的mRNA水平（P <0.001）均显著低于nos2a+/+ 斑马鱼；出膜68天时，nos2a-/- 斑马鱼的gh1 （P <0.0001）和igf1 （P <0.0001）的mRNA水平同样显著低于nos2a+/+ 斑马鱼。以上结果表明，斑马鱼中nos2a的功能缺失导致鱼体生长受到抑制，而gh1及igf1 mRNA的水平下调是其潜在原因。

Role of nos2a in regulating the growth of zebrafish (Danio rerio)

To explore the role of inducible nitric oxide synthase (Nos2) on fish growth regulation, we generated nos2a deficient (nos2a-/-) zebrafish using CRISPR/Cas9 technology for the first time. By monitoring their growth process, we found the growth trend of nos2a-/- zebrafish was slower than nos2a+/+ zebrafish, and the adult body size of nos2a-/- zebrafish was smaller than that of nos2a+/+ zebrafish (P<0.01): the mean length and weight of nos2a+/+ zebrafish were 29.53 mm and 512.8 mg, respectively, that of nos2a-/- zebrafish was 26.34 mm and 394.4 mg. Additionally, there is no notable difference in the density of muscle fibers (P=0.718) and sectional area of vertebrae (P=0.548) between nos2a+/+ and nos2a-/- zebrafish. Moreover, compared with nos2a+/+ zebrafish at 8 dph (days after hatching), the mRNA level of growth hormone (gh1, P <0.01) and insulin-like growth factor-1 (igf1, P <0.001) of nos2a-/- zebrafish at 8 dph was lower significantly; and it is the same as that at 68 dph: gh1, P <0.0001; igf1, P <0.0001. These findings indicate that the defect of nos2a negatively affected zebrafish growth, and the reduced gene mRNA level of growth hormone was the potential factor.