The involvement of muscle-related genes in the occurrence of scrotal hernia in pigs

Abstract: The incidence of scrotal hernia is still a problem in the swine production, leading to economic losses and reducing the animal welfare. Although some QTLs and candidate genes have already been associated to scrotal hernia, the genetic mechanisms and genes controlling this pathology remain to be clarified. Therefore, this study aimed to identify genes involved in the scrotal hernia occurrence in pigs. Thus, two experiments were performed: 1) RNA-Seq analysis of the inguinal ring tissue from eight 60-days-old Landrace pigs (4 healthy and 4 affected with scrotal hernia) that were sequenced in the Illumina HiSeq 2500 and 2) quantitative PCR (qPCR) of 8 candidate genes chosen from the inguinal ring transcriptome in 18 MS115 30-days-old pigs (9 normal and 9 affected with scrotal hernia). Based on the differentially expressed (DE) genes in this transcriptome, some candidate genes related to muscle development biological processes (BP), including the muscle structure (ACTA1), intracellular transport (RYR1, MYBPC1), cell adhesion (COL13A1) and apoptosis (MAP1LC3) were found. The expression profile of the DE genes was consistent with the anatomical alterations related to the scrotal hernia development, such as the weakness of the inguinal canal and non-obliteration of the processus vaginalis. In the qPCR analysis, the MYH1 was the only DE gene identified. The downregulation of the MYH1gene might be one of the possible causes of scrotal hernia in swine since its expression had already been reduced in 30-days-old affected pigs. Therefore, the DE genes identified in our study related to muscle development bioprocesses are possibly involved in the occurrence of scrotal hernia in pigs. Resumo: A incidencia de hernia escrotal ainda e um problema na producao de suinos, levando a perdas economicas e reduzindo o bem-estar animal. Embora alguns QTLs e genes candidatos ja tenham sido associados a hernia escrotal, os mecanismos geneticos e os genes que controlam esta patologia ainda precisam ser esclarecidos. Portanto, este estudo teve como objetivo identificar genes envolvidos na ocorrencia de hernia escrotal em suinos. Assim, foram realizadas duas experiencias: 1) Analise de RNA-Seq do tecido anelar inguinal de oito suinos Landrace com 60 dias de idade (4 saudaveis ? e 4 afetados com hernia escrotal) que foram sequenciados no Illumina HiSeq 2500 e 2) PCR quantitativa (qPCR) de 8 genes candidatos escolhidos do transcriptoma do anel inguinal em 18 porcos MS115 com 30 dias de idade (9 normais e 9 afetados com hernia escrotal). Com base nos genes diferencialmente expressos (DE) neste transcriptoma, alguns genes candidatos relacionaram-se aos processos biologicos (BP) de desenvolvimento muscular, incluindo a estrutura muscular (ACTA1), transporte intracelular (RYR1, MYBPC1), adesao celular (COL13A1) e apoptose ( MAP1LC3) foram encontrados. O perfil de expressao dos genes DE foi consistente com as alteracoes anatomicas relacionadas ao desenvolvimento da hernia escrotal, como a fraqueza do canal inguinal e a nao obliteracao do processo vaginal. Na analise qPCR, o MYH1 foi o unico gene DE identificado. O downregulation do gene MYH1 pode ser uma das possiveis causas de hernia escrotal em suinos, uma vez que sua expressao ja havia sido reduzida em suinos afetados com 30 dias de idade. Portanto, os genes DE identificados em nosso estudo relacionados a bioprocessos de desenvolvimento muscular estao possivelmente envolvidos na ocorrencia de hernia escrotal em suinos.