Whales, lifespan, phospholipids, and cataracts

Douglas Borchman,Raphaela Stimmelmayr,J Craig George

doi:10.1194/jlr.m079368

Douglas Borchman, Raphaela Stimmelmayr + Show 1 more

Open Access

https://doi.org/10.1194/jlr.m079368

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Abstract

This study addresses the question: why do rats get cataracts at 2 years, dogs at 8 years, and whales do not develop cataracts for 200 years? Whale lens lipid phase transitions were compared with the phase transitions of other species that were recalculated. The major phospholipids of the whale lens were sphingolipids, mostly dihydrosphingomyelins with an average molar cholesterol/phospholipid ratio of 10. There was a linear correlation between the percentage of lens sphingolipid and lens lipid hydrocarbon chain order until about 60% sphingolipid. The percentage of lens sphingolipid correlated with the lens lipid phase transition temperature. The lifespan of the bowhead whale was the longest of the species measured and the percentage of whale lens sphingolipid fit well in the correlation between the percentage of lens sphingolipid and lifespan for many species. In conclusion, bowhead whale lens membranes have a high sphingolipid content that confers resistance to oxidation, allowing these lenses to stay clear relatively longer than many other species. The strong correlation between sphingolipid and lifespan may form a basis for future studies, which are needed because correlations do not infer cause. One could hope that if human lenses could be made to have a lipid composition similar to whales, like the bowhead, humans would not develop age-related cataracts for over 100 years.

Highlights

This study addresses the question: why do rats get cataracts at 2 years, dogs at 8 years, and whales do not develop cataracts for 200 years? Whale lens lipid phase transitions were compared with the phase transitions of other species that were recalculated
Lens dissection, and lipid extraction Unlike globe enucleation from humans and animals obtained from the local abattoir, whose death and globe dissection occur at room temperature, whales globes were harvested in ideal conditions
The lens of the bowhead whale is very important for focusing light onto the retina because, unlike terrestrial mammals, the cornea of the bowhead whale is not refractive in water and of little optical importance [75]

Summary

Introduction

This study addresses the question: why do rats get cataracts at 2 years, dogs at 8 years, and whales do not develop cataracts for 200 years? Whale lens lipid phase transitions were compared with the phase transitions of other species that were recalculated. There was a linear correlation between the percentage of lens sphingolipid and lens lipid hydrocarbon chain order until about 60% sphingolipid. The percentage of lens sphingolipid correlated with the lens lipid phase transition temperature. The lifespan of the bowhead whale was the longest of the species measured and the percentage of whale lens sphingolipid fit well in the correlation between the percentage of lens sphingolipid and lifespan for many species. Bowhead whale lens membranes have a high sphingolipid content that confers resistance to oxidation, allowing these lenses to stay clear relatively longer than many other species. One could hope that if human lenses could be made to have a lipid composition similar to whales, like the bowhead, humans would not develop age-related cataracts for over 100 years.—Borchman, D., R.

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