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Ching-fong Chang - One of the best experts on this subject based on the ideXlab platform.
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Activation of the brain-pituitary-gonadotropic axis in the black Porgy Acanthopagrus schlegelii during gonadal differentiation and testis development and effect of estradiol treatment
General and Comparative Endocrinology, 2019Co-Authors: Chien-ju Lin, Sylvie Dufour, Ching-fong ChangAbstract:Previous studies revealed an estradiol (E2)-dependent peak in brain activity, including neurosteroidogenesis and neurogenesis in the black Porgy during the gonadal differentiation period. The brain-pituitary-gonadotropic axis is a key regulator of reproduction and may also be involved in gonadal differentiation, but its activity and potential role in black Porgy during the gonadal differentiation period is still unknown. The present study analyzed the expression of regulatory factors involved in the gonadotropic axis at the time of gonadal differentiation (90, 120, 150 days after hatching [dah]) and subsequent testicular development (180, 210, 300 dah). In agreement with previous studies, expression of brain aromatase cyp19a1b peaked at 120 dah, and this was followed by a gradual increase during testicular development. The expression of gonadotropin subunits increased slightly but not significantly during gonadal differentiation and then increased significantly at 300 dah. In contrast, the expression of brain gnrh1 and pituitary gnrh receptor 1 (gnrhr1) exhibited a pattern with two peaks, the first at 120 dah, during the period of gonadal differentiation, and the second peak during testicular development. Gonad fshr and lhcgr increased during gonadal differentiation period with highest transcript level in prespawning season during testicular development. This suggests that the early activation of brain gnrh1, pituitary gnrhr1 and gths, and gonad gthrs might be involved in the control of gonadal differentiation. E2 treatment increased brain cyp19a1b expression at each sampling time, in agreement with previous studies in black Porgy and other teleosts. E2 also significantly stimulated the expression of pituitary gonadotropin subunits at all sampling times, indicating potential E2-mediated steroid feedback. In contrast, no significant effect of E2 was observed on gnrh1. Moreover, treatment of AI or E2 had no statistically significant effect on brain gnrh1 transcription levels during gonadal differentiation. This indicated that the early peak of gnrh1 expression during the gonadal differentiation period is E2-independent and therefore not directly related to the E2-dependent peak in brain neurosteroidogenesis and neurogenesis also occurring during this period in black Porgy. Both E2-independent and E2-dependent mechanisms are thus involved in the peak expression of various genes in the brain of black Porgy at the time of gonadal differentiation.
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1 Conserved Sex-Specific Timing of Meiotic Initiation During Sex
2016Co-Authors: Differentiation Protandrous, En-lieng Lau, Mong-fong Lee, Black Porgy Acanthopagrus, Running Meiotic, Protandrous A Teleost, Ching-fong ChangAbstract:Meiosis is an essential mechanism of gametogenesis for all sexually reproducing species. In vertebrates, one conserved aspect of sex differentiation is that female embryonic germ cells enter meiosis earlier than male germ cells. In some lower vertebrates, female germ cells proliferate prior to entering meiosis, whereas male cells remain in mitotic arrest. Protandrous black Porgy fish, Acanthopagrus schlegelii, have a dramatic life cycle involving a characteristic sex change. Black Porgy are functional males for their 1st and 2nd spawning seasons, but approximately half of the fish transform into females during their 3rd year. We cloned the black Porgy homologs of dosage suppressor of mck1 homolog (dmc1), and synaptonemal complex protein 3 (sycp3), and examined their expression profiles as well as those of cytochrome P450 family 26 genes (cyp26: cyp26a and cyp26b), retinaldehyde dehydrogenases (raldh: raldh2 and raldh3), retinoic acid receptors (rars: rarα, rarβ, rarγand rarγb), retinoid X receptors (rxrs: rxrα, rxrβ and rxrγ) and deleted azoospermia-like (dazl) during gonadal sex differentiation by RT-PCR, qRT-PCR and immunohistochemistry. Our results show that during gonadal development, germ cells located in ovarian tissue proceed into meiosis earlier than germ cells in testicular tissue. Furthermore
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Current Status of Genetic and Endocrine Factors in the Sex Change of Protandrous Black Porgy, Acanthopagrus schlegeli (Teleostean)
Annals of the New York Academy of Sciences, 2005Co-Authors: Yanhorn Lee, Mong-fong Lee, Ching-fong ChangAbstract:Black Porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite fish, is functionally male for the first 2 years of life, but begins to sexually change to female after the third year. Testicular tissue and ovarian tissue are separated by connective tissue in the bisexual gonad. This sex pattern provides a unique model to study the mechanism of sex change in fish. The annual profiles of plasma estradiol, vitellogenin, and 11-keto-testosterone concentrations in males were significantly different from those in the 3-year-old females. Oral administration of estradiol stimulated high levels of gonadal aromatase activity, plasma luteinizing hormone (LH) levels, and sex change in the 2-year-old fish. Oral administration with aromatase inhibitors for 1 year further blocked the natural sex change in 3-year-old black Porgy and all fish became functional males. Transcripts of estrogen receptor (ER), androgen receptor, and gonadotropin receptors in the ovarian tissue of bisexual gonad were significantly less expressed than those in the bisexual testicular tissue. ER and aromatase transcripts were much higher in the vitellogenic ovary than those in the bisexual ovarian tissue. Plasma LH levels were higher in male fish than sex-changing fish during postspawning and nonspawning season in 2 + -year-old black Porgy. We are also conducting investigations on the role of the genetic factors (Dmrt 1, Sox 9, Sf-1, and Dax-1) in sex development and sex change. An endocrine mechanism of sex change in black Porgy is proposed.
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Identification of 17,20β,21-trihydroxy-4-pregnen-3-one as an oocyte maturation-inducing steroid in black Porgy, Acanthopagrus schlegeli
General and comparative endocrinology, 2004Co-Authors: Wen Shiun Yueh, Peter Thomas, Ching-fong ChangAbstract:Abstract The identity of the maturation-inducing steroid (MIS) in black Porgy, Acanthopagrus schlegeli , a marine protandrous teleost, is unknown. Previous studies demonstrated that two teleost MISs, the progestins 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) and 17,20β-dihydroxy-4-pregnen-3-one (DHP) can induce maturation of black Porgy oocytes in vitro. The purpose of the present study was to identify the major progestin produced during oocyte maturation (OM) in black Porgy and investigate whether its secretion increases during this process. Females were injected twice with a LHRH analog to induce OM. Ovarian follicles undergoing OM were incubated in vitro with tritiated [ 3 H]pregnenolone precursor and the tritiated products were extracted, purified, and identified by HPLC, TLC, acetylation, and recrystallization. Significant amounts of tritiated products were biosynthesized from [ 3 H]pregnenolone that co-migrated with 20β-S but not with DHP on HPLC and TLC. Similar TLC profiles were obtained with the tritiated products isolated from the HPLC/TLC 20β-S fraction and standard 20β-S after the acetylation reaction. The identity of the tritiated products as 20β-S was confirmed by recrystallization. 20β-S had a slightly higher potency than DHP in the inducing in vitro final oocyte maturation. Plasma 20β-S concentrations increased significantly during the oocyte maturation after injection with a LHRH analog. The present data suggest that 20β-S is the MIS in black Porgy.
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aromatase inhibitors block natural sex change and induce male function in the protandrous black Porgy acanthopagrus schlegeli bleeker possible mechanism of natural sex change
Biology of Reproduction, 2002Co-Authors: Yanhorn Lee, Wen Shiun Yueh, Liantien Sun, Ching-fong ChangAbstract:The objectives of the present study were to investigate the effects of oral administration of aromatase inhibitors on sex change, milt volume, 11-ketotestosterone (11-KT), and LH in plasma; aromatase activity in gonad, pituitary, and brain in the protandrous fish, black Porgy (Acanthopagus schlegeli Bleeker). Two-year-old functional male black Porgy were divided into two groups; one was fed a control diet and the other was fed a diet mixed with aromatase inhibitors (AIs; fadrozole and 1,4,6-androstatriene-3,17-dione, each 10 mg/kg feed) for 8.5 mo. A significantly higher gonadosomatic index was observed in the AI group. Fish treated with AIs showed complete suppression of natural sex change. Significantly higher levels of plasma 11-KT, LH, and milt volume were shown in the AI group than the controls. Lower aromatase activity in the gonad, pituitary, forebrain, midbrain, and hindbrain in concordance with the suppression of sex change was observed in the AI group. The data show that aromatase is directly involved in the mechanism of natural sex change of protandrous black Porgy. AIs also enhanced male function in concordance with the elevated plasma levels of 11-KT and spermiation in milt volume.
Cheol Young Choi - One of the best experts on this subject based on the ideXlab platform.
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Profiles of antioxidant gene expression and physiological changes by thermal and hypoosmotic stresses in black Porgy (Acanthopagrus schlegeli)
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2010Co-Authors: Na Na Kim, Hyun Suk Shin, Gyung-suk Kil, Cheol Young ChoiAbstract:Abstract We determined oxidative stress by measuring the expression and activity of 3 antioxidant enzymes [Cu/Zn-superoxide dismutase (Cu/Zn-SOD), catalase (CAT) and glutathione peroxidase (GPX)] in black Porgy exposed to thermal (20 °C → 30 °C) and hypoosmotic (35 psu→10 psu and 0 psu) stresses. The expression and activity of antioxidant enzymes were significantly higher after exposure to 30 °C, 10 psu, and 0 psu. Furthermore, we measured H 2 O 2 and lipid peroxidation (LPO) levels. As a result, H 2 O 2 and LPO levels were significantly increased after exposure to thermal (20 °C → 30 °C) and hypoosmotic stress (35 psu→10 psu and 0 psu) stress. These results indicate that thermal and hypoosmotic stress induces oxidative stress in black Porgy. Additionally, we investigated the changes due to thermal and hypoosmotic stress by measuring plasma cortisol and ion (Na + and Cl − ) levels. Plasma cortisol levels increased at 30 °C and at 10 psu and then decreased at 0 psu. However, plasma Na + and Cl − levels did not change after exposure to thermal stress (30 °C), and decreased at 10 psu and 0 psu. In conclusion, thermal and hypoosmotic environments increase oxidative stress, thereby these results may be indicators of oxidative stress in black Porgy.
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Quantitative mRNA expression of sox3 and DMRT1 during sex reversal, and expression profiles after GnRHa administration in black Porgy, Acanthopagrus schlegeli
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2009Co-Authors: Hyun Suk Shin, Mi Seon Park, Min Hwan Jeong, Cheol Young ChoiAbstract:We cloned full-length sox3 cDNA from testis of black Porgy, Acanthopagrus schlegeli. Black Porgy sox3 cDNA consists of 897 base pairs (bp) and encodes a protein of 298 amino acids. We have investigated the expression pattern of sox3 and DMRT1 mRNA during the sex-reverse process from male to female (immature testis, mature testis, testicular portion of mostly testis, ovarian portion of mostly testis, testicular portion of mostly ovary, ovarian portion of mostly ovary and ovary). The expression of sox3 and DMRT1 mRNA was high in mature testis of black Porgy during sex-reverse process. In a histological analysis, testicular portion of gonad was degenerated and the ovary portion was increased during sex reversal from male to female, and then oocytes were increased in ovary. Also we examined the expression of sox3 and DMRT1 mRNA after gonadotropin-releasing hormone analogue (GnRHa) treatment in immature black Porgy. The expression of sox3 and DMRT1 mRNA was increased after GnRHa treatment (in vivo and in vitro experiment) in immature black Porgy. Therefore, we concluded that sox3 and DMRT1 were involved in the development of testis than ovary in black Porgy.
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Gender-related expression of TRα and TRβ in the protandrous black Porgy, Acanthopagrus schlegeli, during sex change processes
General and comparative endocrinology, 2009Co-Authors: Erik R. Nelson, Hamid R. Habibi, Cheol Young ChoiAbstract:We cloned the thyroid hormone receptor alpha (TRalpha) and beta (TRbeta) cDNAs from the ovaries of the protandrous black Porgy and compared the expression levels of TRalpha and TRbeta mRNA during the sex change in black Porgy. We observed that the TRalpha mRNA by quantitative real-time PCR and protein levels by Western blot were highest in the mature ovaries. Additionally, TRbeta mRNA levels were only expressed highly in the mature ovaries when compared to any other gonadal stages. Then, we injected gonadotropin-releasing hormone analogue (GnRHa) to know the effects on TRs mRNA in immature black Porgy. Injection with GnRHa resulted in a significant increase in TRalpha level while significantly reducing TRbeta level after 12h. We concluded that TRalpha was related in testicular development as well as ovarian development and TRbeta was only affect to ovarian development in black Porgy. These results will provide a framework for better understanding of the role of TRs during sex change processes in this fish.
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Molecular characterization of gonadotropin subunits and gonadotropin receptors in black Porgy, Acanthopagrus schlegeli: Effects of estradiol-17β on mRNA expression profiles
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2008Co-Authors: Ki-young Lee, Sung Gyu Yun, Cheol Young ChoiAbstract:The cDNAs of three gonadotropin (GTH) subunits (GTHalpha, FSHbeta, and LHbeta) and two GTH receptors (FSHR and LHR) from pituitary and gonads of black Porgy were cloned. The nucleotide sequences of the GTHalpha, FSHbeta, and LHbeta cDNA were 354, 363, and 414 base pairs (bps) in length with open reading frames (ORF) encoding peptides of 117, 120, and 137 amino acids, respectively. The FSHR and LHR cDNA was 2118 and 2076 bps in length with ORFs encoding peptides of 705 and 691 amino acids, respectively. To study the mechanism of the estradiol-17beta (E(2)) action, we examined the expression pattern of GTH subunit mRNAs in pituitary and GTH-receptor mRNAs in gonads, and the changes of plasma E(2) level when E(2) treatment was applied to immature black Porgy. E(2) treatment increased mRNA expression levels of the genes and plasma E(2) levels, indicating that E(2) stimulated the increases in GTH subunit and GTH-receptor mRNAs. These data indicate that E(2) plays an important regulatory role in the brain-pituitary-gonad axis of immature black Porgy. We provide the molecular characterization and expression of the GTH subunits and GTH receptors during sex change in the protandrous black Porgy.
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molecular characterization and expression of three gnrh forms mrna during gonad sex change process and effect of gnrha on gth subunits mrna in the protandrous black Porgy acanthopagrus schlegeli
General and Comparative Endocrinology, 2008Co-Authors: Erik R. Nelson, Hamid R. Habibi, Cheol Young ChoiAbstract:Abstract Gonadotropin-releasing hormone (GnRH) plays a pivotal role in control of reproduction and gonadal maturation in teleost fish. To investigate the action GnRH in black Porgy ( Acanthopagrus schlegeli) , we examined the mRNA expression of GTH subunits (GTHα, FSHβ, and LHβ) in the pituitary as well as plasma estradiol-17β (E 2 ) level following treatment with a GnRH analog (GnRHa) in immature fish. The expression levels of GTH subunits mRNA and plasma E 2 level were increased after GnRHa injection. We were also able to identify three GnRH forms: salmon GnRH (sGnRH), seabream GnRH (sbGnRH) and chicken GnRH-II (cGnRH-II) by cDNA cloning in the ovary of the black Porgy. Black Porgy gonadal development is divided into seven stages, involving sex change from male to female (immature testis, mature testis, testicular portion of mostly testis, ovarian portion of mostly testis, testicular portion of mostly ovary, ovarian portion of mostly ovary, and mature ovary). In the present study, we investigated the expression pattern of three GnRH molecular forms in the black Porgy gonads at different stages of gonadal development by quantitative polymerase chain reaction (QPCR). The mRNA expressions of sGnRH, sbGnRH and cGnRH-II were found to be higher in mature testis and ovary, compared to gonads at different stages of maturity. The findings support the hypothesis that the three forms of GnRH play important roles in the regulation of hypothalamic–pituitary–gonadal axis, and are likely involved also in gonadal development and sex change in black Porgy.
Li Xi-guo - One of the best experts on this subject based on the ideXlab platform.
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Effects of salinity on digestive enzyme activity and diurnal variation of digestive enzyme activity of young Yellowfin black Porgy Sparus latus
Marine Fisheries Research, 2006Co-Authors: Li Xi-guoAbstract:Studies were conducted on the effect of salinity on digestive enzyme activity and the diurnal variation of digestive enzyme activity of young yellowfin black Porgy (Sparus Latus).The yellowfin black Porgy was cultured at six different salinity(5,10,15,20,25,30).Test results indicated that the activities of protease and lipase were the highest when the salinity was 25,but the activity of α-amylase was the highest when the salinity was 20.The average digestive enzyme activity at the salinity of 20,25 and 30 was much higher than that at the salinity of 5,10 and 15.The study on the diurnal variation of digestive enzyme activity of yellowfin black Porgy showed that the highest activities of protease,α-amylase and lipase appeared at 14∶00,20∶00 and 18∶00,respectively,while the lowest activities of protease,α-amylase and lipase appeared at 12∶00,10∶00 and 6∶00,repectively.
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Effect of pH on the activity of major digestive enzymes in yellowfin black Porgy Sparus latus
South China Fisheries Science, 2005Co-Authors: Li Xi-guoAbstract:The effect of pH on digestive enzyme activity (protease, amylase, lipase) of alimentary organs (hepatopancreas,stomach,gut ) in yellowfin black Porgy (Sparus latus) was studied in this paper. The specific activity of protease at different pH shows that the optimum pH for protease in yellowfin black Porgy were 2.8,7.0 and 7.4 in stomach, hepatopancreas and intestinal canal, respectively. The optimum pH for lipase in yellowfin black Porgy were 7.6,7.2 and 7.6 in stomach, hepatopancreas and intestinal canal, respectively. The optimum pH for amylase in yellowfin black Porgy were were 5.2,4.8 and 6.8 in stomach, hepatopancreas and intestinal canal, respectively.
Bruno Pinaud - One of the best experts on this subject based on the ideXlab platform.
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Strategy-Driven Exploration for Rule-Based Models of Biochemical Systems with Porgy
2019Co-Authors: Oana Andrei, Maribel Fernández, Hélène Kirchner, Bruno PinaudAbstract:This chapter presents Porgy—an interactive visual environment for rule-based modelling of biochemical systems. We model molecules and molecule interactions as port graphs and port graph rewrite rules, respectively. We use rewriting strategies to control which rules to apply, and where and when to apply them. Our main contributions to rule-based modelling of biochemical systems lie in the strategy language and the associated visual and interactive features offered by Porgy. These features facilitate an exploratory approach to test different ways of applying the rules while recording the model evolution, and tracking and plotting parameters. We illustrate Porgy’s features with a study of the role of a scaffold protein in RAF/MEK/ERK signalling.
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EGC - Porgy : a Visual Analytics Platform for System Modelling and Analysis Based on Graph Rewriting
2017Co-Authors: Bruno Pinaud, Oana Andrei, Maribel Fernández, Hélène Kirchner, Guy Melançon, Jason ValletAbstract:Porgy is a visual environment for rule-based modelling based on port graphs and port graph rewrite rules whose application is steered by rewriting strategies. The focus of this demonstration is the visual and interactive features offered by Porgy, which facilitate an exploratory approach to model, simulate and analyse different ways of applying the rules while recording the model evolution, as well as tracking and plotting system parameters.
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Porgy : a Visual Analytics Platform for System Modelling and Analysis Based on Graph Rewriting
2017Co-Authors: Bruno Pinaud, Oana Andrei, Maribel Fernández, Hélène Kirchner, Guy Melançon, Jason ValletAbstract:Porgy is a visual environment for rule-based modelling based on port graphs and port graph rewrite rules whose application is steered by rewriting strategies. The focus of this demonstration is the visual and interactive features offered by Porgy, which facilitate an exploratory approach to model, simulate and analyse different ways of applying the rules while recording the model evolution, as well as tracking and plotting system parameters.
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Porgy : a Visual Analytics Platform for System Modelling and Analysis Based on Graph Rewriting
2017Co-Authors: Bruno Pinaud, Oana Andrei, Maribel Fernández, Hélène Kirchner, Guy Melançon, Jason ValletAbstract:We propose Porgy 1 a visual modelling framework (Fig. 1) designed for specifying, simulating , and analysing complex systems. Porgy is built on top of the open-source visualisation framework TULIP 2. Porgy is based on the use of port graphs with attributes to represent system states. In a port graph, edges connect to nodes at specific points, called ports. Nodes, ports and edges describe the system components and their relationships, while attributes encapsulate the data values associated with entity. We use graph transformations based on port graph rewrite rules to describe the evolution of the system. FIG. 1 – Overview of Porgy: (1) editing a graph; (2) editing a rule; (3) all available rules; (4) the derivation tree, a complete trace of the computing history; (5) editing a strategy.
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This work is licensed under the Creative Commons Attribution License. Porgy: Strategy-Driven Interactive Transformation of Graphs∗
2016Co-Authors: Oana Andrei, Maribel Fernández, Hélène Kirchner, Guy Melançon, Olivier Namet, Bruno PinaudAbstract:This paper investigates the use of graph rewriting systems as a modelling tool, and advocates the embedding of such systems in an interactive environment. One important application domain is the modelling of biochemical systems, where states are represented by port graphs and the dynamics is driven by rules and strategies. A graph rewriting tool’s capability to interactively explore the features of the rewriting system provides useful insights into possible behaviours of the model and its properties. We describe Porgy, a visual and interactive tool we have developed to model complex systems using port graphs and port graph rewrite rules guided by strategies, and to navigate in the derivation history. We demonstrate via examples some functionalities provided by Porgy.
S.e. Wendelaar Bonga - One of the best experts on this subject based on the ideXlab platform.
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The acute stress response of red Porgy, Pagrus pagrus, kept on a red or white background.
General and Comparative Endocrinology, 2006Co-Authors: A.l. Van Der Salm, Michail Pavlidis, Gert Flik, S.e. Wendelaar BongaAbstract:Abstract The skin colour of red Porgy, Pagrus pagrus , can be modified by exposure to different background colours. Red and white background colours brighten the dark skin colour that develops under common culture conditions in red Porgy. To assess whether skin colour is also modified by aquaculture related handling stress, we subjected red Porgy to 5 min of netting stress combined with air exposure. Fish kept on a white background have: (1) a lighter skin colour, which is not influenced by an acute stressor, (2) a less saturated red colour, which significantly decreases 24 h post-handling, and (3) a similar hue as fish kept on a red background. The first plasma parameters to rise after application of the stressor are cortisol, lactate and Na + ; then, glucose levels rose. Other plasma ions (Ca 2+ , Cl − , K + ) were not affected up to 2 h post-stressor, but had decreased at 8 and 24 h after handling. Plasma pH decreased over the first 2 h post-handling, indicative of plasma acidosis upon air exposure. The acidosis then coincided with increases in plasma lactate levels. As αMSH levels were not significantly affected by the stressor while cortisol levels showed a five to tenfold increase, we suggest that following acute stress in red Porgy, plasma cortisol release is controlled by ACTH, perhaps in combination with a sympathic stimulation.
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Effects of husbandry conditions on the skin colour and stress response of red Porgy, Pagrus pagrus
Aquaculture, 2004Co-Authors: A.l. Van Der Salm, Gert Flik, M. Martinez, S.e. Wendelaar BongaAbstract:Red Porgy, Pagrus pagrus, is a potential candidate for aquaculture. However, darkening of the body occurs after capture of wild fish and during farming of cultured animals. In fish, skin pigmentation is hormonally controlled and the main hormone involved in skin darkening, α-melanocyte-stimulating hormone (αMSH), is not only involved in pigmentation but also in the regulation of the response to stressors. In this study, several environmental conditions were evaluated for their potency to influence the skin colour and to evoke a stress response. Background colour was the main factor in controlling skin pigmentation. A light background colour restored the lightness value of the skin up to levels found in wild red Porgy (L*=∼70). The background effect was enhanced by applying blue illumination. Light intensity had no clear effect on the body colour, but a high density of fish had a negative effect on the lightness. Plasma parameters (cortisol, αMSH, glucose, lactate and osmolality) were not influenced by background colour. A stocking density of 25 kg/m3 did not evoke a stress response in contrast to earlier studies on red Porgy, nor influenced the body colour. We propose that this difference can be attributed to the number of fish per volume of water, which was lower than in other studies. This indicates that the number of fish per volume of water rather than the density in kilograms of fish per volume of water is the relevant factor. Furthermore, we suggest that the culture of adult red Porgy can be optimised by maintenance of fish on a light background, thereby restoring the body colour to a more natural hue, without affecting the stress response.
