Analysis Of Hypothalamus And Pituitary Transcriptomics In Angus Cattle And Verification Of Their Correlation With Reproductive Traits

The reproductive performance of livestock and poultry directly affects the quality and economic benefits of future generations.Only by maximizing the reproductive potential of cattle and accelerating the breeding speed of cattle herds can production costs be reduced and economic benefits be brought into play.Therefore,in order to improve the reproductive performance of livestock and poultry,research in this area has not stopped.There is a certain understanding about the regulation mechanism of gonadal axis on reproductive behavior,but it is not completely clear which gene or which gene interaction affects the difference in reproductive performance at different developmental stages.Angus cattle have many advantages,such as rapid growth,strong lactation,and early sexual maturity.They reach sexual maturity at an average age of 12-14 months.Basic mating can be basically done at 18 months of age,and the first fetus can be produced at 30 months of age.At present,due to the excellent meat performance and breeding value of Angus cattle,it is warmly sought after by farmers.Therefore,further improving the understanding of the reproductive regulation network and applying it to the production practice of Angus cattle is the focus of improving the reproductive capacity and increasing the economic value.In this project,6 months,18 months and 30 months of Angus cows were selected and divided into 3 groups according to the age of the month.Each group has 3 heads.The physiological state and body shape of the cows in the group are similar.The pituitary and hypothalamic tissues are taken for high-throughput sequencing,and the differential genes that affect the reproductive performance of Angus cattle are mined according to the gene expression system,which provides a theoretical basis for subsequent breeding improvement and the mining of important candidate genes,and also for Angus cattle.The improvement of the reproductive control network provides an effective basis.After sequencing quality control,in the transcriptome analysis of 18 samples,a total of129.18Gb Clean Data was obtained.The Clean Data of each sample reached 6.30Gb,the GC content was greater than 47.61%,and the base percentage of Q30 was not less than 94.19%.The comparison between the transcriptome data and the reference genome sequence shows that the comparison efficiency of Read and reference genome for each sample is 95.06%-96.53%.Based on the comparison results,gene expression analysis was performed,and two tissues were compared between the two groups at different ages.35 and 50 differential genes were collected in the pituitary and hypothalamus,respectively,and functionally annotated and enriched.analysis.According to the analysis results of the GO and KEGG pathways,compared with 6 months of age,the differential genes of pituitary and hypothalamus at 18 months of age are mainly enriched in the metabolism and immune disease pathways,helping the body to complete the development of various tissues,as well as the growth and development of the body Provide sufficient energy.In addition,the down-regulation of LOC511936 in the hypothalamus activates the ovarian steroid synthesis pathway,affecting the synthesis and release of steroid hormones.At 30 months of age,both the pituitary and hypothalamus can activate calcium signaling pathways and taste transduction pathways.Individually,pituitary differential genes are also enriched in the longevity pathway,aldosterol synthesis and release,and oxytocin signaling pathways.Differential thalamus genes are also enriched in GnRH signaling pathway and phospholipase D signaling pathway.During this period,the functions of hypothalamus and pituitary changed from the regulation of growth and metabolism to the regulation of reproductive behavior.Based on the above results,this experiment screened out pituitary CAMK4 as the main factor affecting the reproductive behavior of 30-month-old cows.The action pathway is mainly reflected in three aspects:1.Ca²⁺influenced pituitary CAMK4 directly affects ovulation and fertilization status through the calcium signaling pathway;2.The down-regulation of PIK2b in the hypothalamus activates the longevity pathway through the calcium signal transduction pathway.The down-regulation of the CAMK4 gene on this pathway causes the down-regulation of PGC-1α,causing oxidative stress damage;3.CAMK4 is in the oxytocin pathway and aldosterol Inhibits steroid hormone synthesis in the synthesis and secretion pathways.In addition,the expressions of GnRH and pituitary gonadotropin were not found in this study,which seems to indicate that the reproductive behavior changes in the early mating period and early postpartum period are not directly regulated by these hormones.The above results provide a theoretical basis for the feeding management of Angus cattle in production,candidate genes for future reproductive performance and genetic breeding improvement.