Fig 2: Molecular mechanism diagram of the photoperiod regulating the seasonal reproduction in female Phodopus sungorus. (A) Regulation mechanism of FSH-Nodal/ALK7 signal pathway under short daylight condition. (B) Regulation mechanism of FSH-Nodal/ALK7 signal pathway under long daylight condition. IGF-1: insulin growth factor 1; GnRH: gonadotropin-releasing hormone; FSH: follicle-stimulating hormone; LH: luteinizing hormone; ALK7: activin receptor-like kinase 7; BAX: bcl-2-associated X protein; Bcl-2: B-cell lymphoma-2; P-Akt: phosphate-Akt; HtrA2: High temperature requirement protein a2.

Fig 3: Levels of the Nodal and ACVR1C protein expression in the ovaries of Phodopus sungorus under three photoperiod conditions. (A,B) Representative immunoblots of the key Nodal and ACVR1C proteins and internal reference proteins (α-tubulin and β-actin) in three different photoperiod groups. (C,D) Relative protein expression of Nodal and ACVR1C. Values are means ± SEM. n = 8. SD, short daylight; MD, moderate daylight; LD, long daylight. * p < 0.05.

Fig 4: Key gene expression levels in the Nodal/ALK7 signaling pathway in the ovaries of Phodopus sungorus under three photoperiod conditions. (A) Nodal, (B) ALK7, (C) SMAD4, (D) XIAP, (E) Akt, (F) HtrA2, (G) DIABLO, (H) Bcl-xL, (I) Bcl2, and (J) BAX. Values are means ± SEM. n = 6. SD, short daylight; MD, moderate daylight; LD, long daylight. * p < 0.05, ** p < 0.01.