Effect of nanoparticles on the biochemical and behavioral aging phenotype of the nematode Caenorhabditis elegans.

Invertebrate animal models such as the nematode Caenorhabditis elegans (C. elegans) are increasingly used in nanotechnological applications. Research in this area covers a wide range from remote control of worm behavior by nanoparticles (NPs) to evaluation of organismal nanomaterial safety. Despite of the broad spectrum of investigated NP-bio interactions, little is known about the role of nanomaterials with respect to aging processes in C. elegans. We trace NPs in single cells of adult C. elegans and correlate particle distribution with the worm's metabolism and organ function. By confocal microscopy analysis of fluorescently labeled NPs in living worms, we identify two entry portals for the uptake of nanomaterials via the pharynx to the intestinal system and via the vulva to the reproductive system. NPs are localized throughout the cytoplasm and the cell nucleus in single intestinal, and vulval B and D cells. Silica NPs induce an untimely accumulation of insoluble ubiquitinated proteins, nuclear amyloid and reduction of pharyngeal pumping that taken together constitute a premature aging phenotype of C. elegans on the molecular and behavioral level, respectively. Screening of different nanomaterials for their effects on protein solubility shows that polystyrene or silver NPs do not induce accumulation of ubiquitinated proteins suggesting that alteration of protein homeostasis is a unique property of silica NPs. The nematode C. elegans represents an excellent model to investigate the effect of different types of nanomaterials on aging at the molecule, cell, and whole organism level.