Thyroid-mediated otolith growth in tilapia was evaluated by the ontogenic triiodothyronine (T3) profile revealed by radioimmunoassay during the first month after hatching. Thyroid hormone receptor genes (TRalpha and TRbeta) were cloned and only the expression of TRalpha mRNA, quantified by real-time PCR, was similar to the T3 profile. Variations in otolith growth showed median correlation with the T3 profile and TRalpha mRNA expression pattern. Hypothyroidism and hyperthyroidism were induced in tilapia juveniles and larvae by administration of different concentrations of thiourea (TU) and T3, respectively, for 13 days. T3 and TU had little effect on otolith growth during the larval stage. However, T3 increased otolith growth and TU retarded, or stopped, otolith growth during the juvenile stage. Furthermore, TU treatment caused permanent changes in otolith shape in the ventral area. Otolith growth recovered slowly from hypothyroidism, requiring 2 days to form an increment during the first week. These results suggest that otolith growth, at least during the juvenile stage, is regulated by the thyroid hormones and the process may be mediated by TRalpha.
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http://dx.doi.org/10.1242/jeb.013748 | DOI Listing |
Sci Rep
January 2025
Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA.
Hypoxia tolerance and its variation with temperature, activity, and body mass, are critical ecophysiological traits through which climate impacts marine ectotherms. To date, experimental determination of these traits is limited to a small subset of modern species. We leverage the close coupling of carbon and oxygen in animal metabolism to mechanistically relate these traits to the carbon isotopes in fish otoliths (δC).
View Article and Find Full Text PDFJ Fish Biol
December 2024
Instituto de Diversidad y Ecología Animal (IDEA), CONICET (Consejo Nacional de Investigaciones Científicas Y Técnicas), Córdoba, Argentina.
Age and growth patterns of fish provide important information about the effects of environmental disturbances, which can be used as comparative tools in subsequent studies that attempt to assess freshwater quality. The main goal of our study was to provide information on relevant biological aspects of a native fish species used as a bioindicator in an extensive area of South America. In particular, we evaluated the age and growth patterns of Cnesterodon decemmaculatus (Poeciliidae) to establish reference species values and to compare them in different sites along an environmental quality gradient in a South American freshwater system.
View Article and Find Full Text PDFAtractoscion macrolepis was described as a species separate to A. aequidens, distinguished by a geographically-separated distribution, genetic evidence and a diagnostic meristic character: the number of pored lateral line scales. However, the distinction of these species and description of A.
View Article and Find Full Text PDFAnimals (Basel)
November 2024
Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, P.O. Box 712, P.C. 19013 Anavyssos, Attiki, Greece.
Otoliths are important structures for balance and hearing of fish and constitute a useful tool in fisheries science. This study provides, for the first time in the Mediterranean, information on the otolith morphometrics of , collected from the South Aegean Sea, and enriches the existing information on its age and growth by sex. The otolith shape variables examined showed a more circular to square otolith shape, related to the body size.
View Article and Find Full Text PDFMar Pollut Bull
December 2024
College of Marine Living Resource Sciences and Management, Shanghai Ocean University, Shanghai 201306, China; Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan. Electronic address:
Fluctuating Asymmetry (FA) in fish otoliths is an indicator of arbitrarily tiny variations between bilateral otolith characters, and it serves as an effective indicator of growth and developmental differences due to environmental conditions. Due to their unique resident traits, the Coilia brachygnathus can provide a potential insight to the environmental pressure reflected by its otolith FA. In this study, 228 C.
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