Meeting Abstract
Zebrafish have become a popular physiological and biomedical model organism; however, these fish do not represent the normal growth seen in many teleost fish that is characterized by the continual addition of muscle fibers throughout life. Zebrafish somatic growth is characterized as more determinate-like, with a growth plateau reached around sexual maturity. Skeletal muscle growth is governed by a balance between protein synthesis and protein degradation, with a decrease in protein synthesis and increase in protein degradation leading to muscle wasting or atrophy. While zebrafish have been widely used to study; sarcopenia, metabolic disorders, and obesity, pathways associated with starvation, atrophy, and autophagy have not been well characterized in this species. Therefore, primary myogenic cultures were established from the adult zebrafish skeletal muscle to study the mechanisms of skeletal muscle wasting (atrophy) in this species. To induce atrophy, cultures were treated with minimal media and measures of gene expression associated with autophagy/atrophy and proteasomal pathways were measured using qPCR. The differential regulation of transcription factors paired-box 3/7 and myocyte enhancing factor 2 were also measured to assess their regulation during starvation in myotube cultures. Multiple markers of both autophagy and atrophy were upregulated following starvation in the minimal media, which led to questions about chromatin environment. Further investigations revealed the minimal media imparted a repressive nature at multiple loci related to myogenic progression. Overall zebrafish appear more sensitive to small bouts of starvation than indeterminate growing teleosts, and this physiological deviation provides insight into their evolutionary history and may lead to insights into different growth paradigms.
