ABSTRACT: Nitrogen starvation drives meiosis in yeasts1, while retinoic acid (RA) is required for mammalian meiosis through the activation of its germline-specific target, stimulated by retinoic acid gene 8 (Stra8).Here, by using single-cell transcriptome analysis of wild-type and Stra8-deficient testes, our data revealed that the expression of major metabolic genes are downregulated during germ cell entry into meiosis. Recently, we collected mouse testicular cells from wild-type and Stra8-deficient mice at postnatal day 12 (P12) and P21 for single cell RNA-sequencing (scRNA-seq). Upon scRNA-seq, we obtained a total of 23,470 cells from these samples. Using stringent quality control, 22,839 cells were selected for further analysis. All cells, including both wild-type and Stra8-deficient testicular cells, were pooled together to perform clustering analysis, which revealed 6 major cell clusters based on their distinct gene expression patterns. We annotated these six clusters by using known marker genes, including spermatogonia (SPG; Stra8; 3,941 cells), spermatocyte (SPC; Syce1; 4,924 cells), spermatid (STD; Acrv1; 710 cells), Sertoli cell (SC; Sox9; 9,488 cells), Myeloid (MYD; Acta2; 3,531 cells), and Leydig Cells (LY; Star; 245 cells). There is an increase in the percentage of spermatogonia in Stra8-deficient testes at both P12 (28% versus 14% in wild-type) and P21 (17% versus 10% in wild-type). At P21, while spermatocytes are abundant and spermatid are formed in wild-type testes, there are only a few spermatocytes (0.2% versus 73% in wild-type), and spermatids are absent in Stra8-deficient testes. Signature genes are enriched for GO terms for distinct biological function and metabolic pathways in different cell types.
