Dataset Information

High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.

ABSTRACT: Salmonids are generally considered to have a robust genetic sex determination system with a simple male heterogamety (XX/XY). However, spontaneous masculinization of XX females has been found in a rainbow trout population of gynogenetic doubled haploid individuals. The analysis of this masculinization phenotype transmission supported the hypothesis of the involvement of a recessive mutation (termed mal). As temperature effect on sex differentiation has been reported in some salmonid species, in this study we investigated in detail the potential implication of temperature on masculinization in this XX mal-carrying population. Seven families issued from XX mal-carrying parents were exposed from the time of hatching to different rearing water temperatures ((8, 12 and 18°C), and the resulting sex-ratios were confirmed by histological analysis of both gonads. Our results demonstrate that masculinization rates are strongly increased (up to nearly two fold) at the highest temperature treatment (18°C). Interestingly, we also found clear differences between temperatures on the masculinization of the left versus the right gonads with the right gonad consistently more often masculinized than the left one at lower temperatures (8 and 12°C). However, the masculinization rate is also strongly dependent on the genetic background of the XX mal-carrying families. Thus, masculinization in XX mal-carrying rainbow trout is potentially triggered by an interaction between the temperature treatment and a complex genetic background potentially involving some part of the genetic sex differentiation regulatory cascade along with some minor sex-influencing loci. These results indicate that despite its rather strict genetic sex determinism system, rainbow trout sex differentiation can be modulated by temperature, as described in many other fish species.

SUBMITTER: Valdivia K

PROVIDER: S-EPMC4264747 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.

Valdivia Karina K Jouanno Elodie E Volff Jean-Nicolas JN Galiana-Arnoux Delphine D Guyomard René R Helary Louise L Mourot Brigitte B Fostier Alexis A Quillet Edwige E Guiguen Yann Y

PloS one 20141212 12

Salmonids are generally considered to have a robust genetic sex determination system with a simple male heterogamety (XX/XY). However, spontaneous masculinization of XX females has been found in a rainbow trout population of gynogenetic doubled haploid individuals. The analysis of this masculinization phenotype transmission supported the hypothesis of the involvement of a recessive mutation (termed mal). As temperature effect on sex differentiation has been reported in some salmonid species, in ...[more]

PMID: 25501353

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Project description:In this project, effects of chronic temperature changes on the transcriptome of the rainbow trout heart (Oncorhynchus mykiss) were examined. Ectothermic animals of north-temperate latitudes experience large seasonal changes in temperature which strongly affect the rate of body functions. To compensate for the effects of temperature changes ectotherms can respond to chronic temperature changes by increasing the quantity of tissue or enzyme needed for different physiological tasks, or by expressing proteins isoforms which are more appropriate for the new thermal conditions. On the other hand, proteins which are needed in lesser amounts in the new thermal regime could be depressed or down-regulated. Although expression of proteins can be changed by multiple mechanisms during synthesis and degradation, temperature dependent changes in transcription of genes is probably the most important factor in modifying the proteome of the tissues. Rainbow trout are active throughout their thermal tolerance range (0-25°C). Maintenance of adequate cardiac function at different thermal conditions requires a thorough change of the cardiac phenotype which appears as compensatory changes in relative heart mass, energy metabolism, nervous and humoral control of cardiac contractility and in electrical and mechanical properties of the trout heart. Such an extensive structural and functional remodeling of the heart probably necessitates both qualitative and quantitative changes among the numerous macromolecules which constitute the cardiac phenotype and cannot, therefore, be solely based on posttranslational modification of proteins but is expected to require differential gene expression. As a power supply of the circulatory system, the heart is in the focal point of physiological plasticity and sets limits for the activity level of the animal in different thermal conditions. Although several aspects of heart function have been studied in thermally acclimated fish and a number of structural changes have been noticed on exposure to different temperatures, the cellular and molecular mechanisms involved in chronic thermal stress of the fish heart are only partially elucidated. An interesting and poorly examined feature of the cold-acclimated phenotype of the trout heart is the increased heart mass which attenuates the depressive effect of low temperature on cardiac pump function. The heart is a complex organ composed of multiple tissues which together provide the system all necessary qualifications for cardiac pump function. In addition to the contractile and metabolic machinery of the cardiac myocytes, the amount and quality of the extracellular matrix also contribute to the properties of the heart as a muscular pump. Due to the complexity of the heart an enormous amounts of research efforts are needed to find out and examine all crucial aspects of cardiac plasticity required for thermal acclimation. In this regard the screening of gene expression by cDNA micro arrays might provide a broader view to genomic basis of cardiac remodeling under changing temperatures and aid to reveal the candidate genes which are important for thermal acclimation and which might remain unnoticed by traditional biochemical and physiological methods. In the present study we the steady-state effects of temperature acclimation on gene expression of the rainbow trout heart were screened by micro array analysis. Keywords: parallel sample

Project description:BACKGROUND: Fish gonadal sex differentiation is affected by sex steroids treatments providing an efficient strategy to control the sexual phenotype of fish for aquaculture purposes. However, the biological effects of such treatments are poorly understood. The aim of this study was to identify the main effects of an androgen masculinizing treatment (11beta-hydroxyandrostenedione, 11betaOHDelta4, 10 mg/kg of food for 3 months) on gonadal gene expression profiles of an all-female genetic population of trout. To characterize the most important molecular features of this process, we used a large scale gene expression profiling approach using rainbow trout DNA microarrays combined with a detailed gene ontology (GO) analysis. RESULTS: 2,474 genes were characterized as up-regulated or down-regulated in trout female gonads masculinized by androgen in comparison with control male or female gonads from untreated all-male and all-female genetic populations. These genes were classified in 13 k-means clusters of temporally correlated expression profiles. Gene ontology (GO) data mining revealed that androgen treatment triggers a marked down-regulation of genes potentially involved in early oogenesis processes (GO 'mitotic cell cycle', 'nucleolus'), an up-regulation of the translation machinery (GO 'ribosome') along with a down-regulation of proteolysis (GO 'proteolysis', 'peptidase' and 'metallopeptidase activity'). Genes considered as muscle fibres markers (GO 'muscle contraction') and genes annotated as structural constituents of the extracellular matrix (GO 'extracellular matrix') or related to meiosis (GO 'chromosome' and 'meiosis') were found significantly enriched in the two clusters of genes specifically up-regulated in androgen-treated female gonads. GO annotations 'Sex differentiation' and 'steroid biosynthesis' were enriched in a cluster of genes with high expression levels only in control males. Interestingly none of these genes were stimulated by the masculinizing androgen treatment. CONCLUSION: This study provides evidence that androgen masculinization results in a marked dysregulation of early gene expression profiles when compared to natural testicular or ovarian differentiation. Based on these results we suggest that, in our experimental conditions, androgen masculinization proceeds mainly through an early inhibition of female development.

Project description:In this project, effects of chronic temperature changes on the transcriptome of the rainbow trout heart (Oncorhynchus mykiss) were examined. Ectothermic animals of north-temperate latitudes experience large seasonal changes in temperature which strongly affect the rate of body functions. To compensate for the effects of temperature changes ectotherms can respond to chronic temperature changes by increasing the quantity of tissue or enzyme needed for different physiological tasks, or by expressing proteins isoforms which are more appropriate for the new thermal conditions. On the other hand, proteins which are needed in lesser amounts in the new thermal regime could be depressed or down-regulated. Although expression of proteins can be changed by multiple mechanisms during synthesis and degradation, temperature dependent changes in transcription of genes is probably the most important factor in modifying the proteome of the tissues. Rainbow trout are active throughout their thermal tolerance range (0-25Â°C). Maintenance of adequate cardiac function at different thermal conditions requires a thorough change of the cardiac phenotype which appears as compensatory changes in relative heart mass, energy metabolism, nervous and humoral control of cardiac contractility and in electrical and mechanical properties of the trout heart. Such an extensive structural and functional remodeling of the heart probably necessitates both qualitative and quantitative changes among the numerous macromolecules which constitute the cardiac phenotype and cannot, therefore, be solely based on posttranslational modification of proteins but is expected to require differential gene expression. As a power supply of the circulatory system, the heart is in the focal point of physiological plasticity and sets limits for the activity level of the animal in different thermal conditions. Although several aspects of heart function have been studied in thermally acclimated fish and a number of structural changes have been noticed on exposure to different temperatures, the cellular and molecular mechanisms involved in chronic thermal stress of the fish heart are only partially elucidated. An interesting and poorly examined feature of the cold-acclimated phenotype of the trout heart is the increased heart mass which attenuates the depressive effect of low temperature on cardiac pump function. The heart is a complex organ composed of multiple tissues which together provide the system all necessary qualifications for cardiac pump function. In addition to the contractile and metabolic machinery of the cardiac myocytes, the amount and quality of the extracellular matrix also contribute to the properties of the heart as a muscular pump. Due to the complexity of the heart an enormous amounts of research efforts are needed to find out and examine all crucial aspects of cardiac plasticity required for thermal acclimation. In this regard the screening of gene expression by cDNA micro arrays might provide a broader view to genomic basis of cardiac remodeling under changing temperatures and aid to reveal the candidate genes which are important for thermal acclimation and which might remain unnoticed by traditional biochemical and physiological methods. In the present study we the steady-state effects of temperature acclimation on gene expression of the rainbow trout heart were screened by micro array analysis.

Project description:BackgroundRainbow trout is a significant fish farming species under temperate climates. Female reproduction traits play an important role in the economy of breeding companies with the sale of fertilized eggs. The objectives of this study are threefold: to estimate the genetic parameters of female reproduction traits, to determine the genetic architecture of these traits by the identification of quantitative trait loci (QTL), and to assess the expected efficiency of a pedigree-based selection (BLUP) or genomic selection for these traits.ResultsA pedigreed population of 1343 trout were genotyped for 57,000 SNP markers and phenotyped for seven traits at 2 years of age: spawning date, female body weight before and after spawning, the spawn weight and the egg number of the spawn, the egg average weight and average diameter. Genetic parameters were estimated in multi-trait linear animal models. Heritability estimates were moderate, varying from 0.27 to 0.44. The female body weight was not genetically correlated to any of the reproduction traits. Spawn weight showed strong and favourable genetic correlation with the number of eggs in the spawn and individual egg size traits, but the egg number was uncorrelated to the egg size traits. The genome-wide association studies showed that all traits were very polygenic since less than 10% of the genetic variance was explained by the cumulative effects of the QTLs: for any trait, only 2 to 4 QTLs were detected that explained in-between 1 and 3% of the genetic variance. Genomic selection based on a reference population of only one thousand individuals related to candidates would improve the efficiency of BLUP selection from 16 to 37% depending on traits.ConclusionsOur genetic parameter estimates made unlikely the hypothesis that selection for growth could induce any indirect improvement for female reproduction traits. It is thus important to consider direct selection for spawn weight for improving egg production traits in rainbow trout breeding programs. Due to the low proportion of genetic variance explained by the few QTLs detected for each reproduction traits, marker assisted selection cannot be effective. However genomic selection would allow significant gains of accuracy compared to pedigree-based selection.

Project description:BackgroundThe use of molecular genetic technologies for broodstock management and selective breeding of aquaculture species is becoming increasingly more common with the continued development of genome tools and reagents. Several laboratories have produced genetic maps for rainbow trout to aid in the identification of loci affecting phenotypes of interest. These maps have resulted in the identification of many quantitative/qualitative trait loci affecting phenotypic variation in traits associated with albinism, disease resistance, temperature tolerance, sex determination, embryonic development rate, spawning date, condition factor and growth. Unfortunately, the elucidation of the precise allelic variation and/or genes underlying phenotypic diversity has yet to be achieved in this species having low marker densities and lacking a whole genome reference sequence. Experimental designs which integrate segregation analyses with linkage disequilibrium (LD) approaches facilitate the discovery of genes affecting important traits. To date the extent of LD has been characterized for humans and several agriculturally important livestock species but not for rainbow trout.ResultsWe observed that the level of LD between syntenic loci decayed rapidly at distances greater than 2 cM which is similar to observations of LD in other agriculturally important species including cattle, sheep, pigs and chickens. However, in some cases significant LD was also observed up to 50 cM. Our estimate of effective population size based on genome wide estimates of LD for the NCCCWA broodstock population was 145, indicating that this population will respond well to high selection intensity. However, the range of effective population size based on individual chromosomes was 75.51 - 203.35, possibly indicating that suites of genes on each chromosome are disproportionately under selection pressures.ConclusionsOur results indicate that large numbers of markers, more than are currently available for this species, will be required to enable the use of genome-wide integrated mapping approaches aimed at identifying genes of interest in rainbow trout.

Dataset Information

High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.

Publications

High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.

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