@article {8465, title = {Transient Receptor Potential-Vanilloid (TRPV1-TRPV4) Channels in the Atlantic Salmon, Salmo salar. A Focus on the Pineal Gland and Melatonin Production}, journal = {Frontiers in Physiology}, volume = {22}, year = {2022}, month = {01/2022}, pages = {15}, type = {original research}, abstract = {Fish are ectotherm, which rely on the external temperature to regulate their internal body temperature, although some may perform partial endothermy. Together with photoperiod, temperature oscillations, contribute to synchronizing the daily and seasonal variations of fish metabolism, physiology and behavior. Recent studies are shedding light on the mechanisms of temperature sensing and behavioral thermoregulation in fish. In particular, the role of some members of the transient receptor potential channels (TRP) is being gradually unraveled. The present study in the migratory Atlantic salmon, Salmo salar, aims at identifying the tissue distribution and abundance in mRNA corresponding to the TRP of the vanilloid subfamilies, TRPV1 and TRPV4, and at characterizing their putative role in the control of the temperature-dependent modulation of melatonin production{\textemdash}the time-keeping hormone{\textemdash}by the pineal gland. In Salmo salar, TRPV1 and TRPV4 mRNA tissue distribution appeared ubiquitous; mRNA abundance varied as a function of the month investigated. In situ hybridization and immunohistochemistry indicated specific labeling located in the photoreceptor cells of the pineal gland and the retina. Additionally, TRPV analogs modulated the production of melatonin by isolated pineal glands in culture. The TRPV1 agonist induced an inhibitory response at high concentrations, while evoking a bell-shaped response (stimulatory at low, and inhibitory at high, concentrations) when added with an antagonist. The TRPV4 agonist was stimulatory at the highest concentration used. Altogether, the present results agree with the known widespread distribution and role of TRPV1 and TRPV4 channels, and with published data on trout (Oncorhynchus mykiss), leading to suggest these channels mediate the effects of temperature on S. salar pineal melatonin production. We discuss their involvement in controlling the timing of daily and seasonal events in this migratory species, in the context of an increasing warming of water temperatures.}, keywords = {Atlantic salmon, melatonin, pineal organ, Temperature, transient receptor potential vanilloid (TRPV), TRPV1, TRPV4}, doi = {10.3389/fphys.2021.784416}, url = {https://www.frontiersin.org/articles/10.3389/fphys.2021.784416/full?\&utm_source=Email_to_authors_\&utm_medium=Email\&utm_content=T1_11.5e1_author\&utm_campaign=Email_publication\&field=\&journalName=Frontiers_in_Physiology\&id=784416}, author = {Nisembaum, Laura Gabriela and Loentgen, Guillaume and L{\textquoteright}Honor{\'e}, Thibault and Martin, Patrick and Paulin, Charles-Hubert and Fuent{\`e}s, Michael and Escoubeyrou, Karine and Delgado, Maria Jesus and Besseau, Laurence and Falc{\'o}n, Jack} } @article {7824, title = {Temporary turbine and reservoir level management to improve downstream migration of juvenile salmon through a hydropower complex}, journal = {Knowledge \& Management of Aquatic Ecosystems}, year = {2021}, month = {Jan-01-2021}, pages = {4}, abstract = {Developing management rules to improve downstream migration of salmon smolts in large hydropower plants is essential to limit mortality and migration delay. A 2-year telemetry study was conducted to assess the efficiency of temporary measures to enhance the safety and speed of juvenile salmon passage through the Pout{\`e}s dam (Allier River, France). 124 smolts were tracked through the reservoir and downstream of the dam, during implementation of turbine modulation and/or shutdown during night and reservoir level lowering. Level lowering significantly reduced median residence time from 3.4 days to 4.4 hours. However, even with high spill during turbine modulation, the risk of smolt being drawn toward the turbines was increased at low reservoir level due to the site{\textquoteright}s configuration, greater proximity to the surface and weak repulsive effect of the rack. Moreover, results revealed that a substantial proportion of smolts can migrate during daytime and twilight during floods, even at the beginning of the migration period. Thus targeted turbine shutdown has a good potential to protect smolts, but implementation requires studies taking account of site specificities and a flexible approach.}, keywords = {Atlantic salmon, downstream migration, migratory delay, operational management, Turbine shutdown}, doi = {10.1051/kmae/2021004}, url = {https://www.kmae-journal.org/10.1051/kmae/2021004}, author = {T{\'e}tard, St{\'e}phane and Roy, Romain and Teichert, Nils and Rancon, Jocelyn and Courret, Dominique} } @article {7111, title = {Effects of a temperature rise on Atlantic salmon, Salmo salar, melatonin and thyroid hormones during smoltification}, journal = {Journal of Comparative Physiology B}, volume = {190}, year = {2020}, month = {09/2020}, pages = {731-748}, type = {ACL}, abstract = {Smoltification prepares juvenile Atlantic salmon (Salmo salar) for downstream migration. Dramatic changes characterize this crucial event in the fish life cycle, including gills{\textquoteright} Na+/K+-ATPase activity (NKA) and plasma hormonal levels. The triggering of smoltification relies on photoperiod and is modulated by temperature. Both provide reliable information, to which fish adapted for thousands of years, that allows deciphering daily and calendar time. Here we studied the impact of different photoperiod (natural, sustained winter solstice) and temperature (natural, ~ +4{\textdegree}C) combinations, on gills{\textquoteright} NKA, plasma free triiodothyronine (T3), thyroxine (T4) and melatonin (MEL; the time-keeping hormone), throughout smoltification. We also studied the impact of temperature history on pineal gland MEL production in vitro. The spring increase in gills{\textquoteright} NKA was less pronounced in smolts kept under sustained winter photoperiod and/or elevated temperature. Plasma thyroid hormones levels displayed day-night variations, which were affected by elevated temperature, either independently from photoperiod (decrease in T3 levels) or under natural photoperiod exclusively (increase in T4 nocturnal levels). Nocturnal MEL secretion was potentiated by the elevated temperature, which also altered MEL profile under sustained winter photoperiod. Temperature also affected pineal MEL production in vitro, a response that depended on previous environmental acclimation of the organ. The results support the view that the salmon pineal is a photoperiod and temperature sensor, highlight the complexity of the interaction of these environmental factors on S. salar endocrine system, and suggest that climate change might compromise salmon{\textquoteright}s time {\textquotedblleft}deciphering{\textquotedblright} and processes such as smoltification, downstream migration and seawater residence.}, keywords = {Atlantic salmon, melatonin, smoltification, Temperature, thyroid hormones}, doi = {10.1007/s00360-020-01304-2}, url = {https://link.springer.com/article/10.1007/s00360-020-01304-2}, author = {Nisembaum, Laura Gabriela and Martin, Patrick and Fuent{\`e}s, Michael and Besseau, Laurence and Magnanou, Elodie and McCormick, Stephen D and Jack Falcon} } @article {7193, title = {Effects of a temperature rise on melatonin and thyroid hormones during smoltification of Atlantic salmon, Salmo salar}, journal = { J Comp Physiol B}, year = {2020}, month = {03 September 202}, type = {Journal Article}, abstract = {Smoltification prepares juvenile Atlantic salmon (Salmo salar) for downstream migration. Dramatic changes characterize this crucial event in the salmon{\textquoteright}s life cycle, including increased gill Na+/K+-ATPase activity (NKA) and plasma hormone levels. The triggering of smoltification relies on photoperiod and is modulated by temperature. Both provide reliable information, to which fish have adapted for thousands of years, that allows deciphering daily and calendar time. Here we studied the impact of different photoperiod (natural, sustained winter solstice) and temperature (natural, ~ + 4{\textdegree} C) combinations, on gill NKA, plasma free triiodothyronine (T3) and thyroxine (T4), and melatonin (MEL; the time-keeping hormone), throughout smoltification. We also studied the impact of temperature history on pineal gland MEL production in vitro. The spring increase in gill NKA was less pronounced in smolts kept under sustained winter photoperiod and/or elevated temperature. Plasma thyroid hormone levels displayed day{\textendash}night variations, which were affected by elevated temperature, either independently from photoperiod (decrease in T3 levels) or under natural photoperiod exclusively (increase in T4 nocturnal levels). Nocturnal MEL secretion was potentiated by the elevated temperature, which also altered the\ MEL profile under sustained winter photoperiod. Temperature also affected pineal MEL production in vitro, a response that depended on previous environmental acclimation of the organ. The results support the view that the salmon pineal is a photoperiod and temperature sensor, highlight the complexity of the interaction of these environmental factors on the endocrine system of S. salar, and indicate that climate change might compromise salmon{\textquoteright}s time {\textquotedblleft}deciphering{\textquotedblright} during smoltification, downstream migration and seawater residence.}, keywords = {Atlantic salmon, melatonin, Temperature, thyroid hormones}, doi = {10.1007/s00360-020-01304-2}, url = {https://link.springer.com/article/10.1007\%2Fs00360-020-01304-2}, author = {Nisembaum, Laura Gabriela and Martin, Patrick and Fuent{\`e}s, M and Besseau, Laurence and Magnanou, Elodie and McCormick, Stephen and Falc{\'o}n, Jack} }