Short-term and persistent changes to the muscle transcriptome of Lake sturgeon (Acipenser fulvescens) following early-life exposures to elevated temperatures

In fishes, environmental change during early development may impact performance later in life. Exposure to elevated temperatures during these periods may result in a variety of changes to organismal physiology including both short-term and persistent impacts to growth. However, the underlying mechanisms which promote these physiological changes are unclear. In this study, we used mRNA-seq of white muscle tissue to investigate mechanisms underlying short-term (3 vs. 6 months post-hatch) and persistent (3 vs. 13 months post-hatch) impacts of temperature (16 °C, 18 °C, and 20 °C) during early development, which underlie enhanced growth performance in young of year lake sturgeon. Functional analysis of differentially expressed transcripts revealed that in the short-term, elevated temperatures of 20 °C had impacts on transcriptional regulation of epigenetic mechanisms, neuron development, muscle structure and function, and energy supply. Further, persistent effects led to the establishment of increased growth, altered muscle phenotypes, and transcriptional changes to alternative splicing, neuron signaling, as well as muscle type and function. Taken together, these results suggest that at 20 °C, epigenetic modifications may lead to a molecular switch inducing neuromuscular junction proliferation, which in turn alters developmental trajectories by increasing lake sturgeon muscle development and growth. These findings are pertinent to hatchery management processes and the impacts of increasing temperatures in natural environments such as from heat waves during early development, which both may have persistent impacts on the developmental trajectory of fishes.