Abstract
We previously reported autophagy-mediated degradation of nuclei, nucleophagy, in the filamentous fungus Aspergillus oryzae . In this study, we examined whether nuclei are degraded as a whole. We generated A. oryzae mutants deleted for orthologs of Saccharomyces cerevisiae YPT7 and ATG15 which are required, respectively, for autophagosome-vacuole fusion and vacuolar degradation of autophagic bodies. Degradation of histone H2B-EGFP under starvation conditions was greatly decreased in the Δ Aoypt7 and Δ Aoatg15 mutants. Fluorescence and electron microscopic observations showed that autophagosomes and autophagic bodies surrounding the entire nuclei were accumulated in the cytoplasm of Δ Aoypt7 and the vacuole of Δ Aoatg15 , respectively. These results indicate that nuclei are engulfed in the autophagosomes as a whole and transported/released into the vacuolar lumen where they are degraded.