Abstract

C. elegans has a strong tradition for being used in genetic approaches to understanding the aging process. However, currently the worms are being used in a variety of other approaches, such as drug screening, disease modeling, and environmental manipulations. Collectively all these approaches are likely to provide a unique insight into the aging process. The objective of this thesis was to define the localization of peroxisomal proteins whose deficiency affects the rate of chronological aging and post-embryonic development of C. elegans in various tissues of this organism. The thesis focused homologs of human Sterol Carrier Protein x (hSCPx) in C. elegans , their roles and sub-cellular localization. P-44, nlt-1 and dhs-28--are all members of SCP-2 sterol transfer family. My data indicate that P-44 plays vital role in the regulation of dauer formation, delayed egg-laying period, smaller body size, increased lipid accumulation and extended life-span. Nlt-1 also shows extended lifespan by 40% compared with wild type. In this thesis, I also report that P-44, nlt-1 and dhs-28 are involved in fatty acid metabolism. All of these are expressed in the intestine and appear to be peroxisomal. Both P-44 and nlt-1 seem to be required for catabolism of cyclopropane containing fatty acids. P-44 deficiency also blocks the catabolism of pristanic acid. dhs-28 (17-Ý-hydroxysteriod dehydrogenase), on the other hand, only blocks (affects) the pristanic acid pathway. The data reported in this thesis support the view that there is no direct link between the amount of lipid deposits in an organism and a lifespan. This thesis also explored the use of vital lipophilic dye Nile Red (NR) for visualizing fat storage droplets in C. elegans and for elucidating the role of fat regulatory genes in nematode aging. From the data analysis we can conclude that there is no correlation between the levels of triacylglycerols and a specific pattern of NR staining. Thus, NR is not suitable for monitoring body fat in C. elegans . Staining of animals with SBB in combination with the direct assessment of triacylglycerols by TLC is more appropriate for this purpose