Prolonged apoptosis in mitochondria-rich cells of tilapia (Oreochromis mossambicus) exposed to elevated salinity.
The time-course of programmed cell death (apoptosis) during reorganization of gill epithelium in salinity-stressed tilapia was analyzed using a recently developed method based on laser scanning cytometry (LSC) of dissociated gill cells. Apoptosis in mitochondria-rich cells (MRC) was distinguished from that in other cell types using Na(+)/K(+) ATPase (NKA) as a cell-specific marker. Caspase 3/7 activity in MRC, assessed using LSC and microplate assays, increased significantly starting at 6 h of salinity stress and remained elevated for at least 5 days. This time-course of apoptosis in MRC during acute salinity stress was reflected in elevated apoptotic DNA fragmentation. In parallel to induction of apoptosis, MRC showed a pronounced shift to G2 phase of the cell cycle, which is indicative of G2/M cell cycle arrest, and an increase in NKA abundance per MRC. Unlike in MRC, apoptosis was not significantly increased in other gill cell types, although there was a small transient increase in DNA fragmentation at 6 h. G2 arrest was also observed. Overall, we interpret our data as evidence for a significant role of apoptosis in the extensive reorganization of MRC populations that takes place during salinity acclimation, perhaps similar to its well-established role during organismal development.
Kammerer
Brittany D
BD
Department of Animal Science, University of California, Davis, One Shields Avenue, Meyer Hall, Davis, CA 95616, USA.
Kültz
Dietmar
D
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D005880:Gills / Q000166:cytology / Q000502:physiology*; D047569:Laser Scanning Cytometry; D054712:Salinity; D012965:Sodium Chloride / Q000633:toxicity; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D017210:Tilapia / Q000502:physiology*
D012965:Sodium Chloride; D020169:Caspases; D000254:Sodium-Potassium-Exchanging ATPase