| Bovine mastitis is one of the main diseases affecting the development of dairy industry in the world.It will not only affect the milk yield,milk quality and physiological function of dairy cows,but also lead to the early elimination of dairy cows and increase the cost of cattle.Mastitis has always been a research hotspot of dairy cow diseases,but there is no effective solution so far,conventional treatment and prevention methods can not play a good effect,so it is of great significance to study bovine mastitis resistance based on genetic basis.Xinjiang brown cattle as a special variety resources in xinjiang,comparing holstein cows are characterized by a high low high somatic cell count creamy milk protein traits,but relative to other cattle breeds molecular breeding,xinjiang brown cattle molecular disease-resistant breeding relatively lags behind,there are a lot of control in genome mastitis resistance related to the important genetic resources have not yet been fully mining.In this study,xinjiang brown cattle were selected as the research object.Based on the results of GWAS,candidate genes and key loci of mastitis resistance bond of Xinjiang brown cattle were re-screened for bioinformatics analysis,and then advanced molecular biological technologies such as phosphoric acid sequencing RT-QPCR were used to separate the genes from the genome Transcriptome level was used to identify and verify the function of dairy mastitis resistance genes in Xinjiang brown cattle population,and to further study the regulation mode of genetic variation closely related to SCC SCS and mastitis resistance traits It can not only provide new molecular breeding data for improving SCC traits in dairy mastitis,but also has important significance for improving the accuracy of resistance to mastitis in Xinjiang brown cattle by marker-assisted selection.The main results are as follows:(1)Through GWAS reanalysis,six genes related to mastitis resistance in Xinjiang brown cattle were identified,namely,ZRANB3,PIAS1,ACTR3,LPCAT2,MGAT5,SLC37A2.Bioinformatics analysis showed that five genes were directly or indirectly related,namely,DYRK2 ZRANB3 PIAS1 ACTR3 FHIT gene,of which FHIT and PIAS1 genes are involved in the important signaling pathway of regulating mastitis,and play an important role in inflammatory response and cancer suppression.(2)There was no significant difference in the methylation degree of FHIT and PIAS1 genes between the mastitis group and the healthy group(P>0.05).The methylation degree of FHIT gene in the mastitis group(65.97 ± 19.82%)was higher than that in the healthy group(58.00 ± 23.52%).The methylation level of PIAS1 in the mastitis group(11.48±4.12%)was lower than that in the healthy group(12.17 ± 4.25%).The methylation level of CpG3,CpG5 and CpG8 sites in FHIT gene was significantly higher in mastitis group than in healthy group(P<0.01),and the methylation level of CpG15 site in PIAS1 gene was significantly lower in mastitis group than in healthy group(P<0.01).(3)Candidate genes of FHIT and PIAS1 were expressed in the blood of Xinjiang brown cattle in both mastitis group and healthy group to varying degrees,and the expression levels of FHIT and PIAS1 genes in healthy group were significantly higher than those in Xinjiang brown cattle with mastitis group(P<0.01).There was a significant positive correlation between DNA methylation of PIAS1 gene and m RNA expression(P<0.05),while there was no significant negative correlation between DNA methylation of FHIT gene and m RNA expression(P>0.05).In summary,this study screened out 6 candidate genes for mastitis resistance.Combined with the results of previous research groups,the DNA methylation levels and gene expression levels of FHIT and PIAS1 genes in blood of Xinjiang brown cattle with different udder health degrees were analyzed.It provides valuable new markers for molecular marker-assisted selection of mastitis resistance of Xinjiang brown cattle,which is relatively lagging behind,and enrichis basic materials for genetic breeding theory and practice of Xinjiang brown cattle. |
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