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  • 1
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    In:  http://aquaticcommons.org/id/eprint/22423 | 18721 | 2018-04-06 21:46:31 | 22423 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-05
    Description: Rainbow trout (Oncorhynchus mykiss) females grow larger and mature later than males, making all-female stocks economically advantageous. The objective of this research was to develop methods for the production of monosex populations of trout through the use of sex steroids. The synthetic estrogen ethynylestradiol-17α (EE2) was administered in single period-immersion treatment of 400 µg/l for 1, 2, 4 and 8 h to groups of newly-hatched sac fries of rainbow trout and in a 30 day dietary treatment of 5, 10, 15 and 20 mg/kgf of newly swum up fries. 73.4 And 94.5% females were obtained with 1 and 2-h single-immersion of EE2 respectively (38% female in control). However, higher doses progressively reduced the survival drastically. Sex ratios of dietary treatment of fry were 60, 57.4, 78 and 94% females respectively. Treatments also resulted in a slight increase of both weight and length. This increase was related to the method of hormonal exposure (dietary 〉 immersion), but not dosage-dependent for utilized hormone. This demonstrates that the direct feminization of rainbow trout can be achieved and resulted in sex reversal ratio effectively but not decreased the growth, as observed in hormonal sex reversed females, and it would be a noticeable approach to the direct feminization of trout.
    Keywords: Aquaculture ; Biology ; Fisheries ; Ethynylestradiol-17α ; Rainbow trout ; Immersion ; Dietary ; Oncorhynchus mykiss ; hormone ; sex ; Iran
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 304-315
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  • 2
    Publication Date: 2021-07-16
    Description: In order to perform the project, 446 samples of rainbow trout (Onchorhynchus mykiss) from 24 different regions in Iran were collected. About 2-3 g of caudal fin samples was collected from each specimen and preserved in absolute ethyl alcohol and then transferred to the genetic laboratory. Genomic DNA was extracted using the phenol-chloroform method and then DNA content and quality was determined using spectrophotometry and agarose gel electrophoresis, respectively. Polymerase Chain Reaction (PCR) of genomic DNA fin samples was carried out using 10 pairs of microsatellite primers. All PCR products were electrophoresed on 6% polyacrylamide gel and stained with silver nitrate. Following the scoring of alleles, all parameters including allelic frequency, effective number of allele, observed and expected heterozygosity, shanon index, measurement of similarity and genetic distance and Hardy-Weinberg equilibrium, Fst , Rst and gene flow were calculated using AMOVA analysis in the GenAlex and Popgene programs. The results showed that 8 pairs of microsatellite primers were polymorphic. In total, 50 alleles were determined with the range size of 64-280 bp. The locus omyf had maximum number of allele (26) and loci OTSG 474 and Strurruta58 had minimum number of allele (5). The observed heterozygosity was between 0.86 and 0.964. Hardy-Weinberg departure was observed for all loci from farms 18, 15, 4, E20 and 21 and were disequilibrium (P〈0.05). The farms 14, 8, 7 and 6 were equilibrium at 3 loci, but showed disequilibrium in other loci. The other farms were equilibrium at 1 or 2 loci and disequilibrium at 8 or 9 loci. The FST results showed that maximum FST (0.24) were between farms 1 and 11in which had minimum of gene flow (3.7). Minimum FST (0.04) were between farms 8 and 9 in which had maximum of gene flow (346). Based on the results of AMOVA analysis, significant differences were detected between all farms (P〈0.01). Furthermore, based on Nei 's standard (1972) maximum genetic distance (0.89) were observed between farms 2 and 11 and maximum genetic similarity (0.15) were detected between farms 3 and 4. This result suggests that the unique genetic variation of rainbow trout in hatchery farms of Iran represents a highly valuable genetic resource and provide useful information for creating a based population in the future breeding programs.
    Keywords: Biology ; Iran ; Genetic ; Population ; Rainbow trout ; Onchorhynchus mykiss ; Brood stocks ; Microsatellite ; Samples ; Specimens ; DNA ; PCR ; ANOVA
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 78
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  • 3
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    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25767 | 18721 | 2018-10-13 08:03:37 | 25767 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: The sex reversal technique in fish is widespread in many countries. The development of these techniques is desirable because rainbow trout males reach their gonad maturity earlier compared to the females. Rainbow trout alevins were treated with 17α-methyltestosterone incorporated in the diet (0.5. 1.5, 3, 6 and 10 mg/kg) for 60 days from the beginning of first feeding. Sex was determined at 180 and 680 dpf by sampling fish (n = 20) from each group and examining gross gonadal morphology under a dissecting microscope. Also sex reversal ratio and growth performance were determined in hormone-treated groups. These sex reversed functional males were reared for brood stock until they attained sexual maturity. At the end of experiment, normal rainbow trout eggs were fertilized with the sperms taken from sex reversed males for producing all-female populations. Examination of the results showed that 17α- methyltestosterone was effective in all treatment. The highest sex reversal ratio with 100% was observed in group treated with 0.5, 1.5 and 3 mg/kg 17α- methyltestosterone. The highest live weight ratios were observed in groups fed with 6, 0.5 17α-methyltestosterone and control group. Female progeny produced from the sex reversed males were 100 % in all males that sired offspring. All female trout stocks produced by this method have advantage in rainbow trout culture since the fish is not meant for direct human consumption and is used to generate brood stock, therefore, difference of growth parameters do not influence the success.
    Keywords: Aquaculture ; Biology ; Iran ; Sex differentiation ; Oncorhynchus mykiss ; Sex reversal ; Hormone treatment ; 17-αmethyltestosterone ; Female ; Population ; Steroids ; Gonad ; Maturity ; Rainbow trout ; Sexual
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 38
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  • 4
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    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25308 | 18721 | 2018-09-08 16:30:57 | 25308 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: In many species of finfish, females exhibit higher growth rates than males and achieve larger sizes. In addition, in some species, males mature before reaching marketable size. Therefore, there is great interest from the fish farmers to produce all-female stocks. In this project tried to reversing the sex of rainbow trout larvae by 17 estradiol and direct method, further more finding the optimum dose of this natural estrogen for endocrine sex reversion of Rainbow trout (O. mykiss). Four experimental treatments were designed with doses of 10, 20, 30 and 40 mg/kgf. Trout which treated with 40 mg/kgf yielded 96% female and greatest growth.
    Keywords: Biology ; Iran ; Rainbow trout ; Sex control ; Gonad ; 17-B Estradiol ; Species ; Finfish ; Females ; Males ; Growth ; Mature ; Larvae ; O.mykiss
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 32
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