| Umbilical hernia(UH)is one of the most common hernias in humans and mammals,with the second highest incidence among all hernias.It has a great impact on the quality of human life and the economic value of animal husbandry.UH is a multi-gene recessive genetic disease,which leads to the lack of ideal experimental objects or animal models.Therefore,current human clinical studies on umbilical hernia focus on treatment methods,while the research on pathogenesis and susceptibility genes progresses slowly.For breeding needs,researchers have used pigs,cattle,etc.as experimental objects,and have successively discovered some umbilical hernia susceptibility genes.However,due to factors such as different populations and genetic instability,there is a lack of repeatability between studies.In 2009,we found a case of umbilical hernia in SD rats.Due to the characteristics of short reproductive cycle and easy feeding of rats,we took individuals with umbilical hernia as parents.After more than 30 generations of inbreeding,we successfully established UH rat lines with stable inheritable umbilical hernia traits.In addition,long-term inbreeding can preserve and maintain homozygous umbilical hernia susceptibility genes in UH rats,which is conducive to the discovery of susceptibility genes.The purpose of this study was to determine the biological characteristics and genetic background of UH rats,and to study the umbilical hernia susceptibility genes by WGS sequencing and transcriptome sequencing.In this study,phenotypic characteristics,growth curve,organ coefficient,blood routine and blood biochemical indexes of UH rats were firstly explored.In terms of phenotypic characteristics,UH rats had obvious hernia sac structure,and the contents were mainly intestinal tissue.Male hernia sac was significantly larger than female in adult individuals,and there was no significant correlation between the size of the hernia sac and body weight among same-sex individuals.The typical hernia ring structure with the loss of muscle around the umbilicus and thickening of connective tissue at the margin was evident in the anatomical and pathological sections.In terms of other biological characteristics,the weight of male UH rats was significantly lower than that of SD rats of the same age from the fourth week,and there was no significant difference between females.The spleen of UH rats increased non-pathologically,and the liver coefficient of female UH rats decreased non-pathologically.Compared with SD rats,blood routine and blood biochemical indexes were significantly changed.Immunohistochemical results of abdominal wall of UH rats showed that the ratio of connective tissue typeⅠand type Ⅲ collagen was decreased.The above results indicate that the umbilical hernia of UH rats has the same appearance characteristics,pathological and collagen changes as that of humans and other mammals,making it an ideal model for the study of umbilical hernia.At the same time,this strain has formed unique biological characteristics that are different from SD rats.Next,the genetic background of UH rats was explored through microsatellite DNA marker genetic testing and biochemical loci detection.The results showed that the genetic information of UH rat population was low polymorphism,all genetic structural parameters met the characteristics of inbreeding population,and biochemical loci results met the criteria for inbreeding.The results showed that the UH rat inbred line had been successfully established,which had the characteristics of homology in genetic composition and small differences in individual gene composition,which was conducive to the exploration of susceptible genes and pathogenesis.A total of 22 candidate genes for umbilical hernia susceptibility were obtained by WGS sequencing analysis.Exon annotation analysis showed that there were 3 SNP non-synonymous mutation genes and 1 Indel mutation gene in the above genes.The results of fluorescence quantitative expression detection showed that the expression level of candidate genes CPM was increased in the abdominal wall of 10-week-old rats,indicating that CPM may be one of the genes that cause the occurrence of umbilical hernia.In conclusion,this study successfully established a UH rat inbred population with100% spontaneous umbilical hernia.This population is an ideal animal model for the study of hereditary umbilical hernia due to its stable onset,homologous genetic composition,and consistent phenotype.At the same time,this study clarified the biological characteristics and genetic background of UH rats,and provided phenotypic characteristics and basic data support for their use in umbilical hernia research.In addition,WGS sequencing analysis found that CPM is a susceptibility gene for umbilical hernia,and the discovery of this gene provides research ideas for subsequent mechanism research,diagnosis and treatment screening. |
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