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Genetic research

Variable Effects of Environmental Stressors on Juvenile Fish Growth and Gene Expression

Strategic Insights

— 1 min read

Research conducted at Wilfrid Laurier University in Waterloo, Canada, has investigated the impact of limited food availability, elevated total ammonia, and exposure to 17a-ethinylestradiol (EE) on the growth of juvenile mummichog (Fundulus heteroclitus) at two temperatures (20 and 25 °C). The study aimed to explore the effects of these environmental stressors on the growth hormone (GH)-insulin-like growth factor-1 (IGF-1) pathway in muscle and liver tissues.

Key Takeaways:

  • The study found that limited food availability resulted in decreased growth in juvenile fish, accompanied by reduced liver igf1 and muscle ghra expression, as compared to excess-fed fish.
  • Exposure to elevated total ammonia levels did not affect the expression of GH-IGF-1 pathway genes (igf1, igf1ra, igf1rb, ghra, ghrb) in liver and muscle, despite significant reductions in growth.
  • The study also found that growth (body weight, specific growth rate) of fish held at 25 °C was greater than 20 °C, with NHCl inhibition of growth observed at both temperatures.
  • The temperature-induced increase in growth did not affect the expression of GH-IGF-1 pathway genes after 21 days.
  • The increased temperature resulted in lower actual EE exposure concentrations, but EE did not affect growth at either temperature.
  • The research concluded that further studies are required to characterize the role of the GH-IGF-1 pathway in mummichog and the mechanism by which temperature and contaminants such as ammonia alter juvenile fish growth.
  • Authors Andrea Lister and Deborah MacLatchy, along with lead researcher Olena Kuntyj, contributed to the study.
  • The research has been peer-reviewed and published in Comparative Biochemistry and Physiology C-toxicology & Pharmacology.

Statistics:

  • 21-day experiment: limited-fed fish exhibited decreased growth concomitant with reduced liver igf1 and muscle ghra expression.
  • 21-day experiment: growth (body weight, specific growth rate) of fish held at 25 °C was greater than 20 °C.
  • 33-day experiment: significant reductions in growth were observed in fish exposed to elevated total ammonia levels.
  • GH-IGF-1 pathway genes (igf1, igf1ra, igf1rb, ghra, ghrb) in liver and muscle were not affected by ammonia exposure.

Sources:

  • Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2025:110294.
  • Elsevier Science Inc, Ste 800, 230 Park Ave, New York, NY 10169, USA.
  • Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
  • Olena Kuntyj, Dept. of Biology and Canadian Rivers Institute, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.

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