APPLICATIONS OF FTIR MICROSPECTROSCOPY TO DISSECT THE CHANGES IN MOLECULAR COMPOSITION OF AGING Caenorhabditis elegans OOCYTES
The decline in reproductive capacity is one of the first signs of aging and represents a considerable health problem in modern societies such as Canada with an increasing maternal age. To prepare for challenges brought up by older maternity, there is a need to understand the biology of reproductive aging at the molecular level. For instance, what are the biochemical signatures associated with aging oocytes that precede and predict the incipient loss in fertilizing ability in these cells? The simple nematode C. elegans has a short reproductive span during which it displays a corresponding drop in oocyte quality overtime thus providing a tractable and relevant model to study germ cell aging. Here, FTIR (Fourier Transform Infrared) microspectroscopy was systematically applied as an imaging platform to address in vivo changes in the macromolecular composition of C. elegans oocytes transitioning from reproductive to post-reproductive stages. Using this pioneering experimental approach optimized to image C. elegans cells, a marked increase in lipid and protein signatures consistent with an altered mobilization of yolk (lipoprotein) was detected in old wild-type oocytes. These results were corroborated using standard fluorescent and transgenic techniques demonstrating a spike in lipoprotein storage in aged oocytes. Finally, a bona fide mutant defective in yolk import served as a proof of method to validate the usefulness and reliability of FTIR microspectroscopy as a mapping tool to quickly and reproducibly draw the biochemical landscape of aging oocytes. Overall, this exploratory study supports a role of lipotoxicity in driving oocyte aging and provides an integrated experimental approach for further studies aimed at dissecting the molecular underpinnings behind reproductive decline in germ cells.
Fourier transform infrared microspectroscopy, C. elegans, oocyte, yolk, reproduction
Master of Science (M.Sc.)