Blue Death of Nematodes

Abstract

This paper demonstrates that the aging and death of nematodes, which is accompanied by the emission of a blue glow under a fluorescent microscope, are not directly associated with either lipofuscin (aging pigment) or with anthranilic acid (degradation product of tryptophan residues). It turns out that the parasitic light scattered on the worm cuticle and organs substantially contributes to the blue fluorescence of live and dead nematodes, as well as to blue flashes in dying worms. In spectrofluorimetry, anthranilic acid contributes greatly to the fluorescence in the blue region; however, its overall content measured by this method relative to the total protein amount is, conversely, lower in adult individuals than in younger ones. Artificial aging by heating did not lead to anthranilic acid accumulation. Aging of the nematode seems to result from strong cross-linking among the proteins. The tryptophan fluorescence and light scattering in homogenates favor this suggestion, since old worms have a large amount of denatured proteins, which can be observed by the long-wave shift in the tryptophan fluorescence. Moreover, large cross-linked protein particles that cannot be destroyed by detergents can be observed according to the light scattering.