These effects on conidiation have been found so far for all pex mutants in which PTS1 protein peroxisomal localization has been lost, but not in the pexG mutant

specifically lacking PTS2 protein import (Hynes et al., 2008). Similar to pexC∷bar, the growth of pexBΔ on the short-chain fatty acid (C4) butyrate and the long-chain fatty acid (C18) Buparlisib in vivo oleate as sole carbon sources was inhibited while growth on acetate was not affected and was only slightly affected on l-proline (Fig. 2b). The pexBΔ strain was crossed to a veA+ strain (MH11283: genotype yA2 pabaA1; veA+). Fifty percent of the progeny had phenotypes corresponding to pexBΔ consistent with a single gene mutation and with fertility in heterozygous crosses. The pexBΔ; veA+ strain shown in Fig. 2a was isolated from this cross. Selfed crosses of both pexBΔ and pexBΔ; veA+ strains were fertile, producing mature cleistothecia. However, as described previously for other pex mutants (Hynes et al., 2008), sexual development was slower than for the wild type and cleistothecia

were smaller (not shown). Strains containing the veA+ allele produce more cleistothecia than veA1 strains (Kim et al., 2002), and this was observed for the pexBΔ; veA+ strain (not shown). The production of mature cleistothecia by pexBΔ; veA+ is shown in Fig. 2c. Selfed crosses RXDX-106 of the pexBΔ strains produced viable progeny, as determined by single colony development from plated ascospores. The release of ascospores from squashed cleistothecia is shown Isotretinoin in Fig. 2d and also for the pexC∷bar strain. Overall, it can be concluded that the loss of PexB results in phenotypes identical to those seen in other pex mutants that cause loss of targeting of proteins to peroxisomes. Neither peroxisomes nor the RING-finger peroxin 2 play essential roles in meiosis in A. nidulans. However, because A. nidulans is homothallic, the generality

of this result for all Eurotiomycetes requires examining the effects of pex mutations on mating in heterothallic species. Previously, it has been suggested that the unusual Cys8 Zn2+-binding sequence in the RING-finger peroxins of filamentous ascomycetes might be involved in a unique meiotic function (Kiel & van der Klei, 2009). In addition, Pex2 and Pex12 have protein ubiquitin ligase activities (Platta et al., 2009) and protein ubiquitination independent of a peroxisomal role has been suggested as possibly being involved in meiosis (Peraza-Reyes et al., 2008). Clearly, neither of these possibilities are generally true for ascomycetes. To our knowledge, the roles of Pex2, Pex10 and Pex12 have not been investigated in Sordariomycetes other than P. anserina. It would be of interest to investigate this in N. crassa and M. grisea. However, differences within Sordariomycetes are already apparent. Loss of the importomer protein Pex14 results in male sterility in N. crassa, but not in P. anserina (Managadze et al., 2007; Peraza-Reyes et al., 2008).