Fig. 3

PS-NPs induce germ cell apoptosis and meiotic double strand-breaks (A) Immunofluorescence images of control (upper panel) and PS-NPs exposed (lower panel) adult zebrafish males using caspase-3 (green), DNA counter stained with DAPI (blue). Each green dot corresponds to a caspase-3 positive spermatocyte I cell. Scale bar 50 µm. (B) Bar chart representation of the relative frequency of caspase-3 positive cells per spermatocyte I testicular cyst (Chi-square, *p < 0.05). A total of 883 spermatocyte I control clusters and 811 spermatocyte I plastic exposed clusters were included in the analysis. Six animals were analyzed, representing three replicates. (C) Schematic representation of zebrafish spermatogenic process with special emphasis on meiosis and prophase I stages, where recombination takes place. (D) Representative immunofluorescence images of primary spermatocytes in different stages of meiosis from control (left panels) and PS-NPs exposed (right panels) adult zebrafish males. Images represent SYCP3 labeling of the chromosomal axes (green) and Dmc1 (red). DNA is counter stained with DAPI (blue). Scale bar 20 µm. (E) Boxplot number of DMC1 foci for each cell type and condition (two-way ANOVA, ***p < 0.001, ns nonsignificant). Boxplots are presented as median values (center line) ± SD. A total of 68 cells were analyzed for the control (n = 23 for leptotene, n = 25 for early zygotene and n = 20 for late zygotene) and 66 cells were analyzed for the exposed individuals (n = 21 for leptotene, n = 25 for early zygotene and n = 20 for late zygotene).