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  • 1
    Keywords: Konferenzschrift ; Fische ; Tierphysiologie ; Fortpflanzung
    Type of Medium: Book
    Pages: XIV, 389 S , Ill., graph. Darst
    Language: English
    Note: [Lit.Verz.]
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  • 2
    ISSN: 1573-5168
    Keywords: estradiol-17β ; 17α ; 20β-dihydroxy-4-pregnen-3-one ; gonadotropin ; vitellogenesis ; ovarian maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The plasma levels of estradiol-17β (E2), 17α, 20β-dihydroxy-4-pregnen-3-one (17,20-P) and gonadotropin (GTH) were measured in brook trout (Salvelinus fontinalis) during the period from the end of vitellogenesis to postovulation. Blood samples were taken according to specific stages of maturation, including germinal vesicle breakdown (GVBD) and ovulation. E2 levels were quite high (∼45 ng/ml) at the end of vitellogenesis (and prior to GVBD) and dropped precipitously by GVBD (∼2 ng/ml). They remained low through ovulation and postovulation. 17,20-P levels were low prior to GVBD (∼0.7 ng/ml) and increased dramatically at GVBD (∼148 ng/ml). The levels of 17,20-P remained high at ovulation (∼142 ng/ml) and then dropped significantly within 24 h to approximately half of the ovulatory values. They decreased even further by 7 days postovulation. GTH levels rose gradually through GVBD and ovulation from a postvitellogenic level of approximately 3 ng/ml to a 7 day postovulatory value of approximately 10 ng/ml. The overall results; 1) decrease in estradiol prior to GVBD, 2) increase in 17,20-P at GVBD and 3) gradual GTH rise through GVBD and ovulation, are similar to those reported for other salmonids.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Aquaculture 250 (2005): 471-479, doi:10.1016/j.aquaculture.2005.03.019.
    Description: The effect of exogenous growth hormone (GH) treatment on the growth of juvenile yellow perch (Perca flavescens) was investigated in four experiments. In the first two experiments, juvenile yellow perch were reared at either 13°C or 21°C, and injected weekly with bovine GH (bGH) at 0.1, 1.0 or 10.0 μg/g body weight for 84 days. No significant growth enhancement in GH-treated fish was measured in fish in either of the experiments. In the third experiment, juvenile yellow perch were treated with estradiol-17β (E2, 15 μg/g of diet), bGH (1.0 μg/g body weight) injected weekly or both hormones for 70 days at 21°C. E2 alone stimulated growth, but no further growth stimulation occurred in the E2 + bGH-treated fish. In addition, no growth enhancement was found in fish treated with bGH alone. We measured no difference in serum insulin-like growth factor-I (IGF-I) levels between the treatment groups at 12 and 24 h after the final injection of GH; however, a drop in IGF-I levels after 24 h was observed. In a fourth study, the effect of recombinant yellow perch GH (rypGH, 0.2 or 1.0 μg/g body weight) injected weekly was evaluated in yellow perch juveniles. The fish were reared for 42 days at 18°C. Neither GH dosages improved growth compared to control-injected and non-injected fish. Taken together, the lack of effect of mammalian GH or rypGH in our experiments suggests (1) low binding affinity between these hormones and the GH receptor in yellow perch, (2) that the endogenous GH levels were already at biologically maximal levels or (3) that other endocrine factors are needed in order for GH to promote yellow perch growth. The reduction in IGF-I levels 24 h after handling suggests a negative effect of handling stress on the GH-IGF-I axis in yellow perch.
    Description: This work was supported by the University of Wisconsin-Madison College of Agricultural and Life Sciences and School of Natural Resources; the Wisconsin Department of Natural Resources; the University of Wisconsin Sea Grant College Program, National Oceanic and Atmospheric Administration, US Department of Commerce; the State of Wisconsin (Federal Grant NA46RG0481, Project No. R/AQ-38); and the USDA NOAA Project R/A-05-99, grant #NA86RG0048 to FG and SR. This study was also funded by the Norwegian Research Council (NFR).
    Keywords: Yellow perch ; GH ; Growth ; IGF-I ; E2
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: 112359 bytes
    Format: application/pdf
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in ICES Journal of Marine Science 63 (2006): 393-399, doi:10.1016/j.icesjms.2005.10.006.
    Description: A number of techniques including expressed sequence tag (EST) analysis, serial analysis of gene expression, and microarrays are available to study the global expression and regulation of genes. Many of these techniques are being used for intensively reared fish such as trout, salmon and catfish to study genes involved in growth, reproduction and health. In contrast, relatively little is known about the composition and regulation of transcriptomes in gadids. However, several bottlenecks in cod mariculture might benefit from the discovery and analysis of genes involved in reproduction, growth and disease. As a result, we have begun EST analysis of genes in the cod ovary. Complimentary DNA (cDNA) libraries of cod ovaries taken from females at oocyte final maturation and ovulation have been constructed, and 1,361 ESTs have been analyzed. As expected, several oocyte-related genes were observed including various zona pellucida egg membrane proteins. However, pivotal cell cycle regulators such as cyclins, genes involved in the regulation of apoptosis such as the Bcl-2-related ovarian killer protein, and hormone receptor components were also observed. Finally, a cDNA for a potential novel cod antifreeze protein was observed 12 times, suggesting the existence of a cod egg-specific antifreeze protein.
    Description: This work was supported in part by grant #139630/140 from the Research Council of Norway to BN and USDA grant #2004-35204-14232 to FWG.
    Keywords: cDNA ; Cod ; EST ; Genomic ; Godus morhua ; Library ; Ovary ; Reproduction
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: 184041 bytes
    Format: application/pdf
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