*2.6. Gene Array Analysis*

Briefly, the RNA samples isolated from three independent PND3 gonocytes and PND8 spermatogonia cell preparations, each made from multiple rat testes (each sample corresponding to the RNA of 60–90 pups for gonocytes, and 10 pup rats for spermatogonia) were analyzed using Illumina RatRef-12 Expression BeadChips, as previously described [18]. The relative levels of antioxidant genes were expressed in arbitrary units and presented as the means ± SEM of all data.

As a comparison, the RNA from an enriched germ cell population prepared from the pooled testes of 4 PND60 adult rats was also analyzed in the gene arrays, as described before [24].


**Table 1.** Primer sets for qPCR analysis of genes in rat gonocytes. The underlined bases correspond to bases added to the gene sequence by the primer design program to generate better-balanced primers.

### *2.7. Lipid Peroxidation Measurement by Bodipy Labelling*

Lipid peroxidation was measured using the fluorescent lipid peroxidation sensor BODIPY 581/591 C11, a reporter fatty acid labelled with bodipy (4,4-difluoro-3a,4adiaza-s-indacene) fluorophore, which can enter the cells and is used as a surrogate for endogenous lipids (Bodipy; Life Technologies (Burlington, Ontario, ON, Canada)). The peroxidation of the reporter fatty acid leads to a shift in the fluorescence of BODIPY from red to green in the cells. Thus, cells presenting green fluorescence corresponds to cells in which lipid peroxidation occurred, which can be quantified by assessing their proportion in each sample. Following 1.5 h of gonocyte treatments with either medium, PRDXs inhibitors and/or H2O2, the Bodipy reagen<sup>t</sup> was added to the wells at 20 μM final concentration for an additional 30 min at 37 ◦C. The reactions were stopped by collecting and centrifuging the cells at 425× *g* for 10 min at 4 ◦C. The pellets were washed with PBS, the cells fixed with paraformaldehyde (3.5% final) for 7 min, washed and further collected by cytospin centrifugation on microscopic slides. For each slide, 5 pictures were taken using FITC (oxidized Bodipy reporter) and Texas Red (non-oxidized reporter) fluorescence, on a Leica fluorescent microscope. Lipid peroxidation was measured as the percent of Bodipy-positive green fluorescent cells over the total gonocyte numbers. Data are shown as the means ± SEM of samples from 3 different experiments.
