Effect of chronic near-ultraviolet radiation on the gray squirrel lens in vivo.

The effects of ambient exposure to near-ultraviolet (near-UV) radiation (300-400 nm) on the ocular lens of the diurnal squirrel (Sciurus carolinensis) are reported. Gray squirrels lived in cages illuminated for 12 hr a day with near-UV light (6 mW/cm2, 365 nm) for 1 yr. The non-UV-exposed controls were housed separately.

Comparative study of lens proteins of gray squirrel and human.

1. The four crystallins of the gray squirrel lens have been characterized using gel filtration chromatography, polyacrylamide gel electrophoresis, and immunoblotting. Alpha, beta-heavy, beta-light, and gamma crystallins of squirrel lenses have been identified immunologically, and they cross-react strongly with rabbit polyclonal antibodies.

The nature and properties of squirrel lens yellow pigment.

The low molecular weight yellow pigment in the gray squirrel lens is confirmed to be n-acetyl-3-OH-kynurenine (NAK). This conclusion is based upon the results of studies of the compound's optical, chromatographic, and mass spectroscopic properties. The original tentative identification of this compound was reported by Van Heyningen (1971, 1973).

Effects of near-UV radiation on the protein of the grey squirrel lens.

In vivo exposure of grey squirrels to 40W BLB illumination resulted in alterations in the state of the lens crystallins, mainly in the outer layer of the lens. HPLC revealed an increase of the void volume or crosslinked crystallins and an increase in peptides with molecular weights lower than 20,000 d. In vitro exposure of squirrel lens aqueous extracts to Woods lamp radiation (predominantly 365 nm) led to similar but more exaggerated changes as viewed by high performance liquid chromatography.

Biochemical features of the grey squirrel lens.

The ocular lens of the grey squirrel (Sciurus carolinensis) is an excellent model for studies of eye-light interactions that apply to the human system. In this diurnal animal, lens size, shape, yellow pigmentation, and light absorption properties have important similarities to those of young children. This article describes the observations of soluble to insoluble protein conversion with chronological aging, and the loss of heavier lens crystallins in the internal as compared to the external layers of the lens.