In general, fish meat that is elastic and hard is preferred by consumers, but few methods have been identified for improving fillet quality. “Xianfeng No. 1”, a new hybrid of Erythroculter ilishaeformis (♀) × Ancherythroculter nigrocauda (♂), is an important species for aquaculture in China. A short-term exercise trial (12 days) was conducted, followed by texture and histomorphology analysis, to determine the influence of exercise on fillet hardness of this hybrid species. Furthermore, transcriptomic and bioinformatic analyses were carried out to better understand the molecular bases under the process of fillet quality formation. There are several novel findings in our study. First, exercise at a moderate velocity (1.2 body lengths per second) for 12 days can significantly increase the muscle texture (i.e., hardness and springiness) of this hybrid species. Second, the hematoxylin and eosin (H&E) staining of muscle sections indicated a decrease in myofiber diameter and increased myofiber density as the exercise duration increased. Third, a total of 2056, 2414, and 3366 differentially expressed genes (DEGs) were identified in the 4, 8, and 12 days treatment groups, respectively. Fourth, the DEGs were enriched in signaling pathways linked to muscle hardening (tight junction and hippo signaling pathways) and glucose metabolism (AMPK signaling pathways and glycolysis/gluconeogenesis). Genes associated with muscle hardening (WNT2B, CDH1, MYCB, MYH1, MYH2, and MYH6), immune defense (MAVS, EPO, and SKAP2), and glucose metabolism (HK1, GAPDH, LDHA, and PGK1) were also identified. From our study, there are several possible molecular bases on which exercise improves fillet hardness: exercise may activate hippo pathway to stimulate hyperplasia to further increase myofiber density, modulate the expression of MYHs to change myofiber type, and activate tight junction signaling pathway to narrow intermyofibrillar spaces. These findings will further accelerate the breeding of more appetizing and disease-resistant species.

一般来说，消费者更喜欢富有弹性和坚硬的鱼肉，但目前还没有找到改善鱼片质量的方法。翘嘴红鲌(♀)× 黑尾红鲌新杂交种“先锋一号”(♂)，是我国水产养殖的重要品种。进行了短期运动试验（12 天），然后进行质地和组织形态学分析，以确定运动对该杂交物种的鱼片硬度的影响。此外，还进行了转录组学和生物信息学分析，以更好地了解鱼片质量形成过程中的分子基础。我们的研究有几个新颖的发现。首先，以中等速度（每秒1.2个体长）锻炼12天可以显着增加这种杂交物种的肌肉质地（即硬度和弹性）。其次，肌肉切片的苏木精和伊红 (H&E) 染色表明，随着运动持续时间的增加，肌纤维直径减小，肌纤维密度增加。三、共2056、2414、在第 4 天、第 8 天和第 12 天的治疗组中分别鉴定出 3366 个差异表达基因 (DEG)。第四，DEG 富含与肌肉硬化（紧密连接和河马信号通路）和葡萄糖代谢（AMPK 信号通路和糖酵解/糖异生）相关的信号通路。与肌肉硬化相关的基因（还鉴定了WNT2B、CDH1、MYCB、MYH1、MYH2和MYH6）、免疫防御（MAVS、EPO和SKAP2）和葡萄糖代谢（HK1、GAPDH、LDHA和PGK1 ）。根据我们的研究，运动改善鱼片硬度有几个可能的分子基础：运动可能激活河马通路刺激增生，进一步增加肌纤维密度，调节MYH的表达改变肌纤维类型，并激活紧密连接信号通路以缩小肌原纤维间隙。这些发现将进一步加速培育更美味、更抗病的物种。