Abstract
Purpose: :
The zebrafish (Danio rerio) is a rapidly emerging animal model for research, due to the their lower maintenance costs and available genetics tools. Zebrafish models have been developed for use in studying various ocular disorders. As for many animal models, there is no standard laboratory diet for zebrafish. The goal of this study was to determine the effects of diet on the levels of crystallins in the lens.
Methods: :
Proteins in the young adult zebrafish lens were resolved by SDS-PAGE and divided into 1 cm bands each of which were digested with trypsin. Tryptic peptides were analyzed by nanoLC-tandem mass spectrometry to identify the proteins. From these data, proteotypic peptides unique to the most abundant crystallins were selected for nanoLC-multiple reaction monitoring-MS analysis. Lenses were collected from zebrafish at 4 months of age that had been reared on diets of varying protein sources (fish hydrolysate [FH], soy protein isolate [SPI], wheat gluten [WG], casein, and a mixture of all four).
Results: :
A total of 306 proteins were identified in the zebrafish lens, of which 73 were crystallins. Seventeen crystallins were selected for quantitation between the different diet groups. The SPI diet group had increased levels of αA-, αB-, and αBb-crystallin, compared to the WG and casein diets. The β- and γ- crystallins were significantly more abundant than the α-crystallins. Intensities of βB2- and βB3-crystallins were the highest of the β-family, and again the SPI group had significantly higher levels than the WG or casein groups. Of the γ-family, γM7-crystallin was the most abundant. However, the γ-crystallins were unaffected by diet.
Conclusions: :
We have successfully developed a method for determining the effects of different diets on individual lens crystallins in zebrafish. The soy protein diet yielded the highest levels of α- and β-crystallins, when compared to the wheat and casein diets. If we assume that greater α-crystallin levels imply a larger chaperone capacity within the lens, this would suggest that the soy diet would be preferential to diets with wheat or casein. However, this method does not take into account truncation of the α-crystallins; additional experiments are needed to determine if the differences in α-crystallins are affected by the presence of truncated species.
Keywords: crystallins • nutritional factors • proteomics