Effects Of Cadmium Exposure On Ovary,Uterus And Testis Of Xiangxi Yellow Cattle Crossbreed Based On Whole Transcriptome Analysis

Heavy metals mean a class of metallic elements with density higher than 5 g/cm3,such as mercury,cadmium,chromium,lead,arsenic,cobalt,etc.Cadmium(Cd),which is a heavy metal toxicant,enters the respiratory,digestive and blood systems mainly through environmental exposure and the food chain,and has adverse effects on the metabolic,reproductive and immune systems.Cadmium contamination has resulted in a series of vicious contamination events,of which the more typical are the cadmium rice incident in China and the Itai-Itai disease incident in Japan.In Hunan Province,there are more non-ferrous metal mines and smelting areas,and cadmium pollution exists in the soil,crops and water sources near these areas.Xiangxi cattle are a local breed of cattle widely raised in Hunan,and their diets commonly contain corn straw silage.Due to the strong ability of corn to enrich cadmium,Xiangxi cattle raised around mining areas are prone to indirect intake of cadmium,which leads to impaired reproductive capacity.In order to investigate the effect of cadmium on the reproductive system,14 6-month-old half-sibling Xiangxi yellow cattle were selected for this study,including 8 females,4 each in the control and treatment groups,and 6males,3 each in the control and treatment groups.The treated group was fed a diet containing 6.07 mg/kg of cadmium for 100 days,and the control group was fed a normal diet,and all ovarian,uterus and testis tissues were taken for whole transcriptome sequencing after slaughter.Based on the differential genes,we explored the toxic effects and mechanisms of cadmium on ovaries,uterus and testes of Xiangxi Yellow cattle,and provided molecular markers for the prevention and treatment of heavy metal poisoning and other cadmium-induced diseases in Xiangxi Yellow cattle,and enriched the theoretical basis of cadmium toxicity.Two libraries were created in this study,with the lncRNA/mRNA library generating an average of 13.65 G of data per sample and the miRNA library generating an average of 23.77 M of data per sample.The Clean Reads for each sample maintained a comparison efficiency of 90.46%-93.23% with the bovine reference genome in NCBI.The proportion of bases with low quality(Quality < 20)was low in this experiment,and the overall quality remained above Q30.In the ovary group(COvsHO)there were 230 differential mRNAs,29 differential miRNAs,and105 differential lncRNAs.In the uterus group(CUvs HU)366 differential mRNAs,40 differential miRNAs,and 66 differential lncRNAs.In the testis group(CTvs HT)168differential mRNAs,12 differential miRNAs,and 48 differential lncRNAs.GO functional annotation and KEGG pathway enrichment analysis were performed for differential mRNAs,and KEGG pathway analysis was performed for target genes of differentially expressed miRNAs and lncRNAs.The results showed that the differential genes in both uterus and ovary were enriched in PI3K-AKT,P53,MAPK,apoptosis and autophagosome signaling pathways.Differential genes in uterus and testis were also enriched in glutathione metabolic pathway.Antigen processing and presentation pathways are specific to the ovary.In addition,CYP1A1 was differentially expressed in uterus,ovary and testis.Among the results of differential miRNA and lncRNA analysis,the ovary group was enriched for Wnt and JAK/STAT signaling pathways,which are associated with embryonic development and cell proliferation,respectively.The uterine group differential miRNAs were enriched to the HIF-1 pathway associated with oxidative stress-induced apoptosis.Testis group partial differential lncRNAs targeted to ATP binding cassette transporter proteins.The above results suggest that oxidative stress occurs in both uterus and testis under Cd exposure,while in ovary,Cd mainly affects cell proliferation,apoptosis,steroid hormone synthesis,and immunity.PI3K-AK,P53 and MAPK signaling pathways all play a role in the ovarian toxicity and uterine toxicity of Cd.In addition,Cd affects androgen transport in the testis via ABC transporter proteins.The related differential mRNAs,miRNAs and lncRNAs were involved in the toxic effects of Cd on ovary,uterus and testis,which provided a new basis for an in-depth study of the toxicity mechanism of Cd.