The technique of induced pluripotent stem cells has significant application value in breeding and preserving the genetic integrity of fish species. However, it is still unclear whether the chemically induced pluripotent stem cells can be induced from non-mammalian cells or not. In this article, we first verify that fibroblasts of fish can be chemically reprogrammed into pluripotent stem cells. These induced pluripotent stem-like cells possess features of colony morphology, expression of pluripotent marker genes, formation of embryoid bodies, teratoma formation, and the potential to differentiate into germ cell-like cells in vitro. Our findings will offer a new way to generate induced pluripotent stem cells in teleost fish and a unique opportunity to breed commercial fish and even save endangered fish species.

Pluripotency is a transient state in early embryos, which is regulated by an interconnected network of pluripotency-related genes. The pluripotent state itself seems to be highly dynamic, which leads to significant differences in the description of induced pluripotent stem cells from different species at the molecular level. With the application of cell reprogramming technology in fish, the establishment of a set of molecular standards for defining pluripotency will be important for the research and potential application of induced pluripotent stem cells in fish. In this study, by BLAST search and expression pattern analysis, we screen out four pluripotent genes (Oct4, Nanog, Tdgf1, and Gdf3) in zebrafish (Danio rerio) and crucian carp (Carassius). These genes were highly expressed in the short period of early embryonic development, but significantly down-regulated after differentiation. Moreover, three genes (Oct4, Nanog and Tdgf1) have been verified that are suitable for identifying the pluripotency of induced pluripotent stem cells in zebrafish and crucian carp. Our study expands the understanding of the pluripotent markers of induced pluripotent stem cells in fish.

Exercise can have beneficial effects on fish. However, there is few studies on the expression profile analysis of muscle growth regulation genes and impact of water flow stress on expression levels of the muscle genes in fish. In this study, myogenic regulatory genes (MyoD), myostatin-regulated genes (Mstnb), myoblast development-related genes (Desmin and MYHC) were displayed high expression in muscle tissues of adult zebrafish. MyoD, MyoG, MRF4 and MYHC are higher expression at the muscle effect stage embryos. And we explore that the 30 days old is critical muscle growth period in zebrafish. Furthermore, water flow stress can enhance the expression levels of myogenic regulatory factors (eg. MyoD, MyoG) and myoblast development-related genes (Pax7, Desmin) in the zebrafish trunk dorsal muscle, while the mRNA levels of myostatin regulatory genes, such as Mstna and Mstnb, are significantly down-regulated. Our results suggest that appropriate water flow stressing for 1–2 weeks could promote zebrafish muscle growth, while zebrafish may be in motor fatigue after four weeks of water flow stress. This research provides a foundation for further exploration of fish exercise physiology and adaptation, and is significant for fish farming and conservation.