title: Apoptosis-like death was involved in freeze-drying-preserved fungus Mucor rouxii and can be inhibited by L-proline.
abstract: Freeze-drying is one of the most effective methods to preserve fungi for an extended period. However, it is associated with a loss of viability and shortened storage time in some fungi. This study evaluated the stresses that led to the death of freeze-dried Mucor rouxii by using cell apoptotic methods. The results showed there were apoptosis-inducing stresses, such as the generation of obvious intracellular reactive oxygen species (ROS) and metacaspase activation. Moreover, nuclear condensation and a delayed cell death peak were determined after rehydration and 24 h incubation in freeze-dried M. rouxii via a propidium iodide (PI) assay, which is similar to the phenomenon of cryopreservation-induced delayed-onset cell death (CIDOCD). Then, several protective agents were tested to decrease the apoptosis-inducing stresses and to improve the viability. Finally, it was found that 1.6 mM L-proline can effectively decrease the nuclear condensation rate and increase the survival rate in freeze-dried M. rouxii.
  
  
  CONCLUSIONS
  (1) apoptosis-inducing factors occur in freeze-dried M. rouxii. (2) ROS and activated metacaspases lead to death in freeze-dried M. rouxii. (3)L-proline increases the survival rate of freeze-dried M. rouxii.
authors.affiliation: China General Microbiological Culture Collection Center, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Wang
authors.affiliation: China General Microbiological Culture Collection Center, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, China. Electronic address: yzwang@im.ac.cn.
authors.forename: Youzhi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D005612:Freeze Drying / Q000379:methods*; D009089:Mucor / Q000378:metabolism*; D011392:Proline / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D011392:Proline; D020169:Caspases
keywords: Apoptosis; Cryopreservation; Freeze-drying; Mucor rouxii; Viability; l-proline