Objective:To study the differential expressions of piRNAs in the seminal plasma of men and the role of piRNAs in spermatogenesis.Methods:We sequenced the seminal plasma samples collected from 187 male infertility patients and 58 normal healthy men,obtained differentially expressed piRNAs,and detected the relative expressions of piRNAs in different types of sperm by RT-qPCR to explore their significance in the diagnosis of male infertility.Using histopathology,RNA-protein pull-down and Western blot,we investigated the action mechanism of piRNAs in spermatogenesis in the mouse model.Results:RT-qPCR of the seminal plasma samples revealed a high expression of hsa_piR_000478 in teratozoospermia and ROC curve analysis showed an auxiliary signifi-cance of hsa_piR_000478 in the diagnosis of the disease(AUC=0.7549).Transfection of hsa_piR_000478 and its homologous se-quence piR_mmu_54800729 into the seminiferous tubules of the mouse model significantly decreased sperm motility,increased the per-centage of morphologically abnormal sperm and destroyed the testicular structure.Molecular biological experiments exhibited a close correlation between piRNAs and the energy metabolism-related pathway,which elevated the level of cell glycolysis and interfered with normal spermatogenesis.Conclusion:hsa_piR_000478 has an auxiliary significance in the diagnosis of male infertility,and piRNAs may interfere with spermatogenesis by affecting the glycolysis-related pathway in the spermatogenic microenvironment of the testis.

Objective:To investigate the impact of ionizing radiation(IR)on the structure and function of the testis and pro-vide some strategies for the prevention and treatment of IR-induced damage(IRD).Methods:Using radiation dose simulation,se-men analysis,hormone testing,electron microscopy and single-cell transcriptome sequencing,we assessed and analyzed a case of IRD.We established a mouse model of IRD to validate the results of single-cell sequencing,and investigated the specific biological mecha-nisms of IRD and potential strategies for its intervention.Results:IR at 1-2 Gy significantly reduced sperm concentration and mo-tility,which gradually recovered after 12 months but the percentage of morphologically normal sperm remained low.It also caused im-balanced levels of various steroid hormones,decreased testosterone and dehydroepiandrosterone sulfate,increased progesterone,prolac-tin,luteinizing hormone,and follicle-stimulating hormone.Electron microscopy revealed damages to the testis structure,including loss of germ cells,atrophy of the seminiferous tubules,nuclear membrane depression of the spermatocytes,mitochondrial atrophy and de-formation,and reduction of mitochondrial cristae.Single-cell sequencing indicated significant changes in the function of the Leydig cells and macrophages and disrupted lipid-related metabolic pathways after IRD.Administration of L-carnitine to the mouse model im-proved lipid metabolism disorders and partially alleviated IRD to the germ cells.Conclusion:Ionizing radiation can cause disorders of testicular spermatogenesis and sexual hormones and inhibit lipid metabolism pathways in Leydig cells and macrophages.Improving lipid metabolism can alleviate IRD to germ cells.