PKA, Caspase 1 and HSP40 Induced Apoptosis under Fungi Starvation

To investigate the influence of starvation on the biochemical response of Aspergillus niger. The biochemical impact of starvation was determined by morphological observation, immunofluorescent analysis, High-performance liquid chromatography (HPLC) and western blot over 8 days. Results showed that starvation can inhibit fungi survival rate in a time-dependent manner. A. niger exhibited active responses to starvation such as secretion of some 40 kDa proteins to manage changes in water balance. Conidiophores disintegrated from lack of nutrient. The immunofluorescent analysis demonstrated elevated ROS accumulation in starved cells (P<0.001). The fluorescent microscopy of the TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labelling) staining showed positive in the starved fungi. The mitochondrial stains revealed that the fluorescence emitted by the normal fungi was higher than the starving ones. Western blot analysis showed that starvation can induce up-regulation expression of cell cycle-associated proteins such as PKA, Caspase 1 and Heat Shock Protein 40 (HSP40). These results suggest that up regulation of apoptosis-associated protein may contribute to fungi apoptosis. In conclusion, starvations can active PKA, Caspase 1 and HSP40 protein to inhibit A. niger growth by inducing cell apoptosis.