Background: An increase in the activity of the pituitary-gonad axis (PG-axis) and gonad development are essential for the onset of spawning migration in teleosts. In the fish Coilia nasus, gonad development and spawning migration up the Yangtze River occurs by the end of each summer. We hypothesized that gonadotropin releasing hormones receptor 2 (GnRH-R2), which together produce a signal that interacts with the PG-axis, may help to regulate spawning migration processes.
Results: In this regard, we (1) characterized the gonadosomatic index (GSI) in the anadromous fish C. nasus; (2) analyzed the GnRH-R2 mRNA expression levels in ovary and brain, and concentrations in the serum; and (3) identified the GnRH-R2 protein distribution in the brain and ovaries. We found strong relationships between all of these indices.
Conclusions: The results indicate that GnRH-R2 could act together to promote spawning during the anadromous migration. There is some evidence that the GnRH-R2 gene expression levels and protein distributions change in association with the migratory behavior.
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http://dx.doi.org/10.1186/s12861-016-0142-9 | DOI Listing |
J Fish Dis
January 2025
Laboratory for Freshwater Ecology and Inland Fisheries, NORCE Norwegian Research Centre, Bergen, Norway.
Pathogens play a key role in individual function and the dynamics of wild populations, but the link between pathogens and individual performance has rarely been investigated in the wild. Migrating salmonids offer an ideal study system to investigate how infection with pathogens affects performance given that climate change and fish farming portend increasing prevalence of pathogens in wild populations. To test for effects of pathogen burden on the performance of a migrating salmonid, we paired data from individual brown trout tagged with acoustic accelerometer transmitters and gill biopsies to investigate how pathogen infection affected whole animal activity during the spawning migration.
View Article and Find Full Text PDFBiol Lett
January 2025
Department of Forestry and Natural Resources, Purdue University, Forestry Building, 195 Marsteller Street, West Lafayette, IN 47907, USA.
Temperate fishes often spawn in response to environmental cues, such as temperature, thereby facilitating larval emergence concurrent with suitable biotic and abiotic conditions, such as plankton blooms. Climatic changes may alter the reproductive phenology of spring- and autumn-spawning freshwater fish populations. Such effects may depend on the sensitivity of reproductive phenology to ambient temperatures.
View Article and Find Full Text PDFSci Rep
January 2025
Thünen Institute of Fisheries Ecology, Federal Research Institute for Rural Areas, Forestry and Fisheries, 27572, Bremerhaven, Germany.
Numbers of European glass eels (Anguilla anguilla) monitored along the Atlantic and Mediterranean coasts of Europe currently serve as the main stock indicator in assessment of this critically endangered species. Spawning, however, takes place exclusively in the Sargasso Sea, several thousand kilometers away. The beginning of its complex lifecycle is characterized by a distant and lengthy larval drift, before the young-of-the-year reach the monitoring stations at the European coasts.
View Article and Find Full Text PDFConserv Physiol
December 2024
Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
The physiological performance of ectotherms is influenced by temperature, raising concerns about the impact of global warming on ectotherms. Understanding the relationship between ecologically relevant temperatures and the physiological performance of ectotherms provides a basis for assessing their resilience to changing environments. Absolute aerobic scope (AAS) is a functional metric of the thermal performance of aquatic ectotherms.
View Article and Find Full Text PDFJ Fish Biol
December 2024
Laboratório de Biologia e Cultivo de Peixes de Água Doce (LAPAD), Aquaculture Department, Agricultural Science Center, Federal University of Santa Catarina, Florianópolis, Brazil.
Fish presence in tailraces is a remarkable management concern in operating hydroelectric power plants (HPP) in Brazilian rivers. Fish get blocked during upstream migration for spawning, and large shoals can last for days in the tailrace; however, the circumstances that attract fish throughout the year to this region are uncertain, especially during drought conditions. To unravel this uncertainty, we modeled the relationship between Pimelodus maculatus abundance and environmental and operational variables (N = 26) in monthly fishing campaigns at the Machadinho HPP (N = 18).
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