Effect of the temperature of activation medium on fish sperm quality: Impact on fertilization in vitro in aquaculture practice

Abstract Motility is a key in spermatozoon function, determining semen quality and fertilizing capacity. Motility in fish spermatozoa occurs when they are diluted in a swimming solution, the adequacy of which is determined by factors which vary by species. Spermatozoon motility rate and velocity, as well as the duration of the motility period, are influenced by the temperature of the swimming medium. Increasing the temperature of the swimming medium has a significant negative effect on spermatozoa motility kinematics. It increases the metabolism rate of cells, causing a mismatch of energy resources and promoting changes in sperm movement. It also generates an increase in the production of reactive oxygen species (ROS) and thus oxidative stress, and moreover results in an inadequate capacity of antioxidant enzymes to protect the cell against the effects of oxidative stress induced by higher temperatures. The aim of this review is to update present knowledge about: mitochondria main source of ATP; the protein phosphorylation related to motility; epigenetic regulation of the temperature of the activation and the role of ion channels in regulation motility. These mechanisms involved in sperm motility are of vital importance in regulating fertilization, all of which can be influenced by the environment. We emphasize the importance of investigating spermatozoon mechanisms in depth, especially in the context of climate change which results in changing water temperatures. Our findings provide a better understanding of fish sperm physiology, and a biological foundation for the further development of spermatozoon motility investigation, and reproduction technologies.