Thompson, Sarah M.2023-01-312023-01-312003https://hdl.handle.net/10182/15805During cataract formation increased lens calcium levels activate endogenous m-calpain. mCalpain is a calcium-dependent protease that cleaves crystallins within the lens resulting in opacification. Lenses were dissected from ovine eyes and kept viable in culture. Cataracts were induced in a third of the lenses using the calcium ionophore ionomycin. A second third were treated with ionomycin and the calcium-chelating agent EGT A. The m-calpain mRNA expression of lenses with these treatments was determined using real-time PCR and compared with the m-calpain mRNA expression of control lenses during 96 hours of culture. The m-calpain mRNA content of the lenses at time 0 was 4.105 x 10⁶ copies/μL of cDNA. The m-calpain mRNA levels in ionomycin treated lenses decreased significantly at 48 hr (P<0.05) and remained low at 96 hr. The control m-calpain mRNA level dropped significantly at 48 hr (P<0.05) then returned to the same level as time zero at 96 hr. The EGTA/ionomycin treated lenses m-calpain mRNA content also fell at 48 hr and rose again to starting levels at 96 hr. The lens calcium concentration of the ionomycin treated lenses was higher at 48 and 96 hr than both the control and the EGTA/ionomycin treated lenses. Cortical opacification of the ionomycin treated lenses had occurred at 48 hr and developed into nearly complete opacification at 96 hr. Apart from some minor opacities the control lenses remained transparent throughout culture. The EGTA/ionomycin treated lenses developed some opacification in the equatorial region. Opacification in the ionomycin treated lenses was accompanied by increased calcium levels. There was also a significant degree of protein leakage from the ionomycin treated lenses at 48 and 96 hr (P<0.01) indicating that the integrity of the lens had been compromised. No protein leakage was detected from control and EGTA/ionomycin treated lenses. In conclusion ionomycin treatment of cultured ovine lenses resulted in increased lens calcium concentrations, increased protein leakage and a calcium-dependent decrease in m-calpain mRNA expression.viii, 67 pagesenhttps://researcharchive.lincoln.ac.nz/pages/rightsm-CalpaincataractmRNAlensreal time PCRcultureionomycincalciumDissertationDigital thesis can be viewed by current staff and students of Lincoln University only. If you are the author of this item, please contact us if you wish to discuss making the full text publicly available.ANZSRC::310101 Analytical biochemistryANZSRC::300306 Animal welfareANZSRC::300999 Veterinary sciences not elsewhere classified