Meeting Abstract
Temperature is known to affect embryogenesis and myogenesis in many fish species. Understanding effects of chronically elevated temperatures on fish muscle development is important for understanding potential effects of warming waters on individual organism health. Epaulette shark (Hemiscyllium ocellatum) eggs were reared and hatched for an average of 189 days at their normal mean environmental temperature (27 °C) and 164 days at an elevated environmental temperature (31 °C), and markers of muscle development as well as oxidative damage were evaluated. We measured muscle fiber size, nuclear density, and satellite cell density as markers of muscle development, heat shock protein expression (Hsp70), and protein and lipid oxidation (2,4-DNPH and 4-HNE, respectively) as markers of global oxidative damage. We found that elevated temperatures caused individuals to hatch earlier and to have smaller body sizes. Also, skeletal muscle growth was at an earlier stage compared to the normal temperature. Muscle fibers at both temperatures were similar in size and nuclear density, but satellite cell density was higher in the sharks raised at the elevated temperature (p< 0.0001). Fibers associated with satellite cells were significantly smaller at the elevated temperature than those at the normal temperature (p<0.0001). Generally, at the normal temperature, muscle fiber growth followed a linear trajectory with age post-hatch while muscle fiber growth under the elevated temperature showed greater variability with age. Total oxidative damage was higher at the elevated temperature (p=0.004) and increased with time (p=0.010), showing that these temperatures may induce oxidative stress which could be detrimental to organismal function and development.
