Tryptophan (TRP) is an essential dietary amino acid that, unless otherwise committed to protein synthesis, undergoes metabolism via the Tryptophan-Kynurenine (TRP-KYN) pathway in vertebrate organisms. TRP and its metabolites have key roles in diverse physiological processes including cell growth and maintenance, immunity, disease states and the coordination of adaptive responses to environmental and dietary cues. Changes in TRP metabolism can alter the availability of TRP for protein and serotonin biosynthesis as well as alter levels of the immune-active KYN pathway metabolites.
View Article and Find Full Text PDFDue to their relatively large production and few restrictions on uses, novel substitutes for historically used per and poly-fluoroalkyl substances (PFAS) are being used and accumulating in the environment. However, due to a lack of information on their toxicological properties their hazards and risks are hard to estimate. Before fertilization, oocytes of two salmonid species, Arctic Char (Salvelinus alpinus) and Rainbow Trout (Oncorhynchus mykiss), were exposed to three PFAS substances used as substitutes for traditional PFAS, PFBA, PFBS or GenX or two archetypical, historically used, longer-chain PFAS, PFOA and PFOS.
View Article and Find Full Text PDFThe aim of this study was to determine the kynurenine (KYN) to tryptophan (TRP) ratio (KTR) in fish tissue to assess its usefulness as a biomarker of acute stress. Laboratory held rainbow trout (Oncorhynchus mykiss) were subjected to an acute stressor and KYN, TRP and cortisol were measured in liver and brain tissues at 4- and 48-h post-stress. The analytical method used to determine our analytes was based on lyophilization, and liquid-solid extraction followed by isotope dilution high-performance liquid chromatography positive ion electrospray tandem mass spectrometry.
View Article and Find Full Text PDFComp Biochem Physiol C Toxicol Pharmacol
October 2019
Thyroid hormones (THs) play an important role in early stages development of fish species. Manual elevation of THs in the embryos improves viability and hatching success. However, the impacts of endocrine disrupting chemicals on THs-treated embryos are unclear.
View Article and Find Full Text PDFBull Environ Contam Toxicol
September 2016
The effects of chronic dietary selenomethionine (SeMet) exposure on the visual system of adult zebrafish and their progeny were investigated. Adult zebrafish were exposed to measured concentrations of 1.1 (control) and 10.
View Article and Find Full Text PDFComp Biochem Physiol C Toxicol Pharmacol
January 2016
The present study was carried out to examine the interactive effects of chronic waterborne copper (Cu) and cadmium (Cd) on tissue-specific metal accumulation and reproduction in fathead minnow (Pimephales promelas). Trios (1 male: 2 female; n=5) of fish were exposed for 21days to: (i) control (no added Cu or Cd), (ii) waterborne Cu (75μg/L), (iii) waterborne Cd (5μg/L), and (iv) Cu and Cd mixture (75 and 5μg/L, respectively). Reproductive output (cumulative egg production) was significantly reduced by Cu but not by Cd.
View Article and Find Full Text PDFDioxin-like compounds of varying toxicities are found in complex mixtures. The toxic equivalency factor (TEF) approach was developed based on the potency of a dioxin-like compound relative to the potency of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) to streamline risk assessment. One limitation of the TEF approach is uncertainty regarding differences in the relative potency of dioxin-like compounds among different species.
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
February 2013
Triphenyltin chloride (TPTC), which has been extensively used in industry and agriculture, can occur at concentrations in the environment sufficient to be toxic. Here, potency of TPTC to modulate genes in a library containing 1,820 modified green fluorescent protein (GFP)-expressing promoter reporter vectors constructed from Escherichia coli K12 strains was determined. Exposure to TPTC resulted in 22 (fold change > 2) or 71 (fold change > 1.
View Article and Find Full Text PDFSelenomethionine (Se-Met) is the major dietary form of selenium (Se). While Se is a required nutrient, it can also influence the physiological stress response because it stimulates greater concentrations of cortisol in blood plasma of exposed fish. However, little is known about the effects of exposure to Se on the ability to cope with a secondary stressor.
View Article and Find Full Text PDFSelenomethionine (Se-Met) is the major dietary form of selenium (Se). Detrimental effects have been associated with exposure to elevated dietary selenium. Previous studies have demonstrated effects of Se on the endocrine system, in particular effects on cortisol and thyroid hormones.
View Article and Find Full Text PDFThyroid hormones (THs) play a vital role in vertebrate neural development, and, together with the beta isoform of the thyroid hormone receptor (TRβ), the development and differentiation of cone photoreceptors in the vertebrate retina. Rainbow trout undergo a natural process of cone cell degeneration during development and this change in photoreceptor distribution is regulated by thyroxine (T4; a thyroid hormone). In an effort to further understand the role of T4 in photoreceptor ontogeny and later developmental changes in photoreceptor subtype distribution, the influence of enhanced in ovo T4 content on the onset of opsin expression and cone development was examined.
View Article and Find Full Text PDFRainbow trout were used to evaluate the relationship between the somatostatin (SS) signaling and the growth hormone (GH)-insulin-like growth factor (IGF) systems during pre-hatch and post-hatch embryonic development. The expression of preprosomatostatins (PPSS), SS receptors (SSTR), GH receptors (GHR), IGF-1, IGF-2, and IGF type 1 receptors (IGFR1) was examined in various regions at the eyed-egg (29 days post-fertilization, dpf;), post-hatch (53dpf), swim-up (68dpf), and complete yolk-absorbed (90dpf) stages. In head, PPSSI mRNA abundance increased during development while that of PPSSII' decreased and that of PPSSII'' remained unchanged.
View Article and Find Full Text PDFQuantitative RT-PCR was used to determine the profiles of expression of 10 growth- or development-related genes in rainbow trout (Oncorhynchus mykiss) embryos prior to the formation of the somatotropic (ST) axis (pituitary somatotrops and liver); embryos were sampled immediately after fertilization and water-hardening (t(0)), 1-h post-fertilization, and 1-, 2-, 5-, 7-, 10- and 13-days post-fertilization (dpf); expression profiles were examined in embryos reared at two temperatures (6.0 and 8.5 degrees C), which had different developmental rates.
View Article and Find Full Text PDFComp Biochem Physiol B Biochem Mol Biol
October 2003
The study examines the dynamics of thyroid hormone (TH) trafficking between rainbow trout (Oncorhynchus mykiss) oocytes and ovarian fluid (OF) to explore the processes involved in the transfer of hormone to the oocytes. We also examined the effects of enhancing oocyte T(3) content and subsequent embryo survival. Oocytes incubated in OF alone had significant losses of THs within 12 h, whereas the T(3) content of oocytes retained in T(3)-enriched OF (10 and 100 microg ml(-1)) was significantly elevated in a dose-dependant manner within 3 h.
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