Entry into the stationary phase is associated with a rapid loss of viability and an apoptotic-like phenotype in the opportunistic pathogen Aspergillus fumigatus.
When the opportunistic pathogen Aspergillus fumigatus entered the stationary phase, there was a rapid loss in cell viability which was associated with the appearance of markers characteristic of apoptosis, namely annexin V-FITC binding to the cytoplasmic membrane, demonstrating exposure of phosphatidylserine to the outer leaflet of the membrane; and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) staining of the nuclei, indicating DNA fragmentation. This was followed later by a loss of membrane integrity as revealed by propidium iodide staining. The development of the apoptotic phenotype was blocked when the protein synthesis inhibitor cycloheximide was added to the culture 1h prior to the onset of the stationary phase, demonstrating active participation of the cell. In addition, intracellular activity against substrates specific for caspase-1 and -8 also increased on stationary phase entry and the development of the apoptotic phenotype was blocked when the cell permeant caspase inhibitor Z-FAD-fmk was present in the medium. Cell death in A. fumigatus during the stationary phase therefore appears to share similarities to apoptotic cell death in higher eukaryotes and to be dependent on a caspase-like activity.
Mousavi
S Amin A
SA
School of Biological Sciences, 1.800 Stopford Building, University of Manchester, M13 9PT Manchester, UK.
Robson
Geoffrey D
GD
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D001232:Aspergillus fumigatus / Q000166:cytology / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D015169:Colony Count, Microbial; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D004271:DNA, Fungal / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D008853:Microscopy; D010641:Phenotype; D010718:Phosphatidylserines / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013194:Staining and Labeling
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004271:DNA, Fungal; D010718:Phosphatidylserines; D011500:Protein Synthesis Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D003513:Cycloheximide; D020169:Caspases