Fig. 1

Determining the differentially expressed short peptides between human mature and immature follicular fluid. A Workflow of the peptidomic analysis of human follicular fluid (FF). The mature (n = 5) and immature (n = 5) FF samples were collected according to a GnRH-ant protocol. The collected FF samples were subjected to ultrafiltration to separate the low-molecular-weight fraction (< 10 kDa) containing endogenous peptides (fragments of proteins). The peptides were prepared and analyzed by mass spectrometry. B Length distribution of fragments from FF. The x-axis represents the number of amino acids in each peptide, and the y-axis represents the amount of each peptide. C Venn plot of the FF peptides identified in this study. The left circle shows peptides from immature FF identified in the experiments (221 in total). The right circle shows peptides from mature FF identified in the experiments (295 in total). A total of 154 differentially expressed peptides between immature and maturated follicles were determined. D Volcano map of differentially expressed short peptides. Red represents the upregulated short peptides, and green represents the downregulated short peptides. E Heat map comparing hits of 21 candidate short peptides between immature FF 1–5 and mature FF 1–5. The color scale bar is located on the left, and red and blue indicate increased and decreased levels of the identified peptide, respectively. F Distributions of differentially expressed short peptides according to their isoelectric point (PI), instability index, aliphatic index, and grand average of hydropathicity (GRAVY)