Study Of Spodoptera Litura Cells Apoptosis Induced By Ultraviolet Radiation

Ultraviolet light(UV)is an important environmental factor ,which has wide ranging effects in evens day life .Overexposure to UV can lead to shin inflammation ,premature aging and altimately cancer.UV-induced apoptosis eliminates UV-damaged cells and thus reduces the likelihood that DNA damaged cells will develop into cancer. Apoptosis is cell type dependent induced by UV.The mechanism of apoptosis is important. However,few researches were gone on the apoptosis in the insect cells.In this works,apoptosis induced by UVC were studied in SL-1 cells.The main results were as follows:Microscopic examination of SL-1cell dealled with UV revealed progressive cell blebbing starting at 8-12h p.i.and culminating in total cell destruction at 24h p.i..The fragmentation of the induced cell nuclei was showed with DAPI .Agarose gel electrophoresis analysis of DNA extracted from dealled cell showed typical DNA ladder.All these supported that UVC treatsed-SL-1 cells undergo apoptosis.The apoptotic percentage of UVC-treated-SL-1 cells was measured by flow cytometry using propidium iodide( PI) staining.Under the flow cytometry assay, effect of UVC on mitochondrial membrane potential(△Ψm) was investigated by Rh-123 staining of cells. The results showed that the Rh-123 fluorescent intensity in SL-1 cells was reduced after treatment for 1 hr,and the declining rate was typical in time-dependent manners.The effects of UVC on apoptosis-related protein cyto c were investigated by western blotting. Cyto c was released from mitochondria to cytosolic after induction for 4hrs.An activation of capase 3 in UVC-induced cells was determined in AC-DEVD-AFC as substrate. At 4h post induction an activity of caspase-3 was measured and gradually increased with time extension.These data indicate that cytchrome c play a key rolr in UVC-induced apoptosis in SL-1 cells and establish a connection between cytchrome c release and subsequent caspase activation in insect cells.