Caracterização molecular de híbridos heteróticos das linhagens Red Stirling e Chitralada da tilápia do Nilo (Oreochromis niloticus)
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Data
2017-08-11
Autores
Herkenhoff, Marcos Edgar [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A tilápia do Nilo (Oreochromis niloticus) possui importância econômica na piscicultura mundial. Com a finalidade de atender à demanda do mercado consumidor, foram desenvolvidas várias linhagens com maior viabilidade econômica, dentre elas a Chitralada, que possui rápido crescimento, e a Red Stirling, com filé de cor rosado, mais apreciado pelo consumidor. Com o objetivo de combinar estas características, foi desenvolvido um híbrido, que apresentou heterose. A pesquisa genética em peixes mostrou a interferência direta e indireta de vários genes no desempenho animal, principalmente os genes relacionados ao eixo GH/IGF e a miostatina (MSTN). Além disso, uma classe de RNAs não-codificadores, os microRNAs (miRNAs), possuem papel fundamental na regulação de vários pontos em vias biológicas conhecidas, principalmente na modulação de genes codificadores de proteínas relacionadas ao crescimento. Portanto, o objetivo deste trabalho foi avaliar a expressão gênica dos genes relacionados ao eixo GH/IGF e MSTN; determinar os miRNAs envolvidos e seus alvos; e avaliar o conjunto de proteínas relacionando-as aos respectivos fenótipos. Amostras biológicas foram coletadas das linhagens Chitralada e Red Stirling e do híbrido (7/8 Chitralada). Para a análise de expressão gênica por RT-qPCR, foram coletadas amostras de cérebro, fígado e músculo branco. Para a análise de miRNAs por RNA-seq, foram utilizados pools das amostras de músculo branco, assim como para a análise por ESI-q-TOF e shotgun. Os genes relacionados ao eixo GH/IGF foram super expressos e a MSTN sub expressa no híbrido em relação aos seus parentais. Os dados de expressão dos miRNAs let-7, miR-122, miR-194 e miR-219 corroboram com os dados de expressão dos genes alvos.. Na comparação entre os perfis de expressão de miRNAs e proteínas, verificou-se que proteínas oriundas de genes alvos de miRNAs sub expressos estavam altamente expressas sugerindo atividade regulatória. Conclui-se que existe uma ação dos miRNAs em proteínas associadas às vias metabólicas relacionadas à heterose na tilápia do Nilo.
Nile tilapia (Oreochromis niloticus) has great economic importance in world fish farming. To attend the commercial demand, several lines were developed, among them: Chitralada, with fast growth, and Red Stirling, with red color fillet of pink, which is more appreciated by the consumer. With the aim to combine the main characteristic of these lines, a crossbreed was developed, which also showed heterosis. Although crossbreeding between lines, or species, is a common breeding strategy for producing animals with heterosis, the molecular mechanisms that affect gene expression and biological pathways to create this phenotype still understood. Genetic research on fish showed the direct and indirect interference of several genes in animal performance, especially genes related to the GH/IGF axis and myostatin (MSTN). In addition, a class of non-coding RNAs, microRNAs (miRNAs), play a key role in regulating many biologically known pathways, mainly growth-related. Therefore, this study aimed to evaluate the GH/IGF axis genes expression and MSTN; determine the miRNAs involved and their targets; and the protein involved in the heterosis fenotype. Morphometric parameters, such as weight and length, were collected from the 4th to the 6th month of life. Biological samples were also collected from the Chitralada and Red Stirling, and their crossbreed (7/8 Chitralada). For the analysis of gene expression by RT-qPCR, brain, liver and white muscle samples were collected, ; for miRNA analysis, samples of white muscle were used, as well as ESI-q-TOF and shotgun GH/IGF axis genes were sup-regulated and the MSTN downregulated in crossbreed in relation to their parents. Analysis of the miRNAs showed that let-7, miR-122, miR-194 and miR-219 in the crossbreed are associated with the qPCR data. Regarding the comparison of the miRNAs and with the proteins, several miRNAs showed to be sub expressed and consequently there was increase in the expression of the proteins that have targets of these miRNAs in their genes. We conclude that there is an action of miRNAs on proteins associated with the metabolic pathways and may be responsible for heterosis in Nile tilapia.
Nile tilapia (Oreochromis niloticus) has great economic importance in world fish farming. To attend the commercial demand, several lines were developed, among them: Chitralada, with fast growth, and Red Stirling, with red color fillet of pink, which is more appreciated by the consumer. With the aim to combine the main characteristic of these lines, a crossbreed was developed, which also showed heterosis. Although crossbreeding between lines, or species, is a common breeding strategy for producing animals with heterosis, the molecular mechanisms that affect gene expression and biological pathways to create this phenotype still understood. Genetic research on fish showed the direct and indirect interference of several genes in animal performance, especially genes related to the GH/IGF axis and myostatin (MSTN). In addition, a class of non-coding RNAs, microRNAs (miRNAs), play a key role in regulating many biologically known pathways, mainly growth-related. Therefore, this study aimed to evaluate the GH/IGF axis genes expression and MSTN; determine the miRNAs involved and their targets; and the protein involved in the heterosis fenotype. Morphometric parameters, such as weight and length, were collected from the 4th to the 6th month of life. Biological samples were also collected from the Chitralada and Red Stirling, and their crossbreed (7/8 Chitralada). For the analysis of gene expression by RT-qPCR, brain, liver and white muscle samples were collected, ; for miRNA analysis, samples of white muscle were used, as well as ESI-q-TOF and shotgun GH/IGF axis genes were sup-regulated and the MSTN downregulated in crossbreed in relation to their parents. Analysis of the miRNAs showed that let-7, miR-122, miR-194 and miR-219 in the crossbreed are associated with the qPCR data. Regarding the comparison of the miRNAs and with the proteins, several miRNAs showed to be sub expressed and consequently there was increase in the expression of the proteins that have targets of these miRNAs in their genes. We conclude that there is an action of miRNAs on proteins associated with the metabolic pathways and may be responsible for heterosis in Nile tilapia.
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Palavras-chave
Heterose, Hibridação, Genética - Pesquisa, MicroRNAs, Tilápia do Nilo, Expressão gênica