The Pattern of Gene Expression (Igf Family, Muscle Growth Regulatory Factors, and Osteogenesis-Related Genes) Involved in the Growth of Skeletal Muscle in Pikeperch (Sander lucioperca) During Ontogenesis

The pikeperch (<i>Sander lucioperca</i>) is an economically important freshwater fish and a valuable food with high market acceptance. It is undergoing important changes in growth and regulatory metabolism during the ontogeny. Hence, the current study aims to investigate the mRNA expression of the growth hormone (<i>gh</i>)/insulin-like growth factor (<i>igf</i>) axis (<i>ghr</i>, <i>igfI</i>, <i>igfbp</i>, <i>igfr</i>), muscle regulatory factors (<i>pax7</i>, <i>myf5</i>, <i>myod</i>, <i>myogenin</i>, <i>mrf</i>, <i>mymk</i>, <i>mstn</i>), and osteogenesis-related genes (<i>colla1a</i>, <i>fib1a</i>, <i>on</i>, <i>op</i>, <i>ostn</i>) from hatching through day 40th post-hatching (DPH). The average total length (TL) of larvae measured at hatching was 3.6 ± 0.4 mm (67 degree days), and at the end of the experiment (40 DPH, 777 degree days), it was 27.1 ± 1.1 mm. The results showed three phases of gene expression in day 0 (egg), larval, and juvenile stages of pikeperch, which can be a progression or transition from the initial state toward the juvenile state. The expression pattern of <i>myf5</i>, <i>mymk,</i> and <i>fib1a</i> genes showed the highest value at day 0. The growth hormone receptor gene (<i>ghr</i>) and <i>igfbp5</i> were raised to 1 DPH, whereas increased expression of <i>igfI</i>, <i>igfII</i>, <i>igf1bp4</i>, <i>igf1rb</i>, <i>myod2,</i> and <i>mrf4</i> was detected at 14 DPH. The <i>myod1</i>, pax7, <i>op</i>, <i>ostc</i>, <i>on</i>, <i>igf1ra,</i> and <i>col1a1a</i> genes were highly expressed at 21 DPH and juvenile stages. According to the PLS-DA model, the most relevant VIPs are <i>myf5</i> and <i>mymk</i> as best markers of earlier stages and <i>igf1ra</i>, <i>ostc</i>, <i>pax7</i>, and <i>ghr</i> as markers of later stages of ontogeny. Results from this study suggest that basal metabolism, growth of body cells and muscles, and bone proliferation and development can be regulated by the dynamic changes in gene expression patterns in this species. The identified genes will help to understand the basic biological process of pikeperch larvae and development, which is very important in pikeperch farming.