Studies of eye lens in poikilothermal animals. III. Long-term incubation of rainbow trout lenses.

Long-term incubation of the lens of rainbow trout, a cold water fish, can be carried out at 0 degrees C, without altering its transparency. This is not possible in mammalian lenses. Rainbow trout lenses maintained their transparency with normal cation levels for 2.5 months in H10 medium, which is a simple balanced salt solution containing glucose. In addition, lactic acid was detected and it was increased depending on the incubation time. However, lactic acid production ceased in glucose-free H10 medium after 10 days and the lenses became cloudy with an increase in Na+ and Ca2+ levels and a decrease in K+ and Mg2+ levels after 14 days. Therefore, rainbow trout lenses need glucose as the energy source to maintain the transparency and cation levels in vitro at 0 degrees C for more than 14 days. Lenses maintained their transparency and normal cation levels in H10 medium with 10% fetal bovine serum (FBS) for 12 months, in Dulbecco's modified Eagle medium (DME medium) for 10 months and in DME medium with 10% FBS for 6 months. FBS, amino acids and vitamins are effective to maintain the transparency of the incubated lenses for a long time. The lactic acid production rate was 8.3 micrograms per day in H10 medium and H10 medium with FBS, and 16.5 micrograms per day in DME medium and DME medium with FBS. These results suggest that the restricted H10 medium with FBS is suitable to maintain the transparency of the incubated lenses rather than the nutritious DME medium with or without FBS.(ABSTRACT TRUNCATED AT 250 WORDS)