Fig. 4

ERE in the sperm fractions sorted based on YOPRO− uptake. We compared the observed number of differentially methylated estrogenic and non-estrogenic Alu and other short transposable sequences based on the expected number in the fractions of spermatozoa either stained or not with YOPRO and in the sperm fractions of infertile patients versus healthy semen donors (A). The observed number of hypomethylated estrogenic Alu sequences and of other short transposable sequences significantly differed from the expected numbers in YOPRO− and YOPRO+ sperm fractions of infertile patients (p = 0.0002, resp. p = 0.007). The fraction of spermatozoa remaining unstained with YOPRO in infertile patients was more likely to contain hypermethylated estrogenic Alu sequences, whereas the fraction of spermatozoa stained with YOPRO was more likely to contain hypermethylated estrogenic Alu sequences (p = 0.004). Based on the X²-values of the estrogenic and non-estrogenic sequences, heat maps were constructed to visualize differences between observed and expected number of sequences based on YOPRO− uptake (B). In the comparisons, in which the observed numbers exceeded the expected number, the X²-values were colored red (positive), whereas in the comparisons, in which the observed number remained below the expected number, the X²-values were colored blue (negative)