Mice

Mice were on a mixed C57BL/6-129/Sv (50-50%) genetic background. They were housed in a licensed animal facility (agreement A67-218-37). All experiments were approved by the local ethical committee (Com'Eth, accreditations 2012-080 and 2012-081) and were supervised by N.V., N.B.G. or M.M., who are qualified in compliance with the European Community guidelines for laboratory animal care and use (2010/63/UE). To inactivate Aldh1a-coding genes in spermatogonia and their descendants, mice carrying loxP-flanked alleles (L2) of Aldh1a1, Aldh1a2 and Aldh1a3 (Raverdeau et al., 2012) were crossed with mice bearing the Tg(Stra8-cre)^1Reb transgene (Sadate-Ngatchou et al., 2008). Cre-mediated ablation by Tg(Stra8-cre)^1Reb transgene occurs in undifferentiated spermatogonia as early as P3 (Gely-Pernot et al., 2015; Sadate-Ngatchou et al., 2008). In F1, Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^L2/L2 females were crossed with males bearing one copy of the transgene (Stra8^tg/0). The resulting males (Stra8-Cre^tg/0;Aldh1a1^+/L2;Aldh1a2^+/L2;Aldh1a3^+/L2) were backcrossed with Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^L2/L2 females to generate mutant males in F2 (Stra8-Cre^tg/0;Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^L2/L2; referred to as Aldh1a1-3^Germ−/− mutants), and their control littermates (Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^{L2/ L2} males). They did not display testis defects and were hereafter referred to as control mice. To generate Aldh1a1^Ser−/− mutants or Aldh1a1-3^Ser−/− mutants, mice carrying loxP-flanked alleles of Aldh1a genes were crossed with mice bearing the Amh-Cre transgene, as described previously (Raverdeau et al., 2012). To generate Aldh1a1-3^{Germ−/−;Ser−/−} compound mutants, Stra8-Cre^tg/0;Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^L2/L2 males were crossed with Amh-Cre^tg/0;Aldh1a1^L2/L2;Aldh1a2^L2/L2;Aldh1a3^L2/L2 females.