Short Report Regulation of Drosophila life-span: Effect of genetic background, sex, mating and social status Konstantin G. Iliadi a , Natalia N. Iliadi a , Gabrielle L. Boulianne a,b, * a Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ont., Canada M5G 1L7 b Department of Molecular Genetics, University of Toronto, Ont., Canada M5S 1A8 article info Article history: Received 15 August 2008 Received in revised form 7 May 2009 Accepted 12 May 2009 Available online 28 May 2009 Keywords: Drosophila melanogaster Longevity Aging Genetic factors Environmental factors abstract During the past decade, model organisms such as Drosophila have made it possible to identify individual genes and pathways that regulate organismal life-span. However, despite the progress made in Drosoph- ila aging research, many longevity studies have often yielded controversial results that can be attributed to differences both in genetic background and in experimental design. Here, we describe the results of a systematic analysis of life-span comparisons in two laboratory wild-type strains. The main goal of these studies is to clarify the effects of social status, mating and sex on life-span with the aim of defining the optimal experimental design whereby the influence of these factors would be minimized. We find that differences in environmental factors and genetic background can be minimized by measuring the life- span of flies that are maintained as mixed-sex groups that allow for regular sexual and social contacts and seems to be more physiologically relevant for estimation of population’s life-span. Taken together, these results may be especially important for screens designed to search for genes that may be involved in longevity as well as for comparative analysis of strains in which the genetic background is unknown or in those cases where it is very difficult to equilibrate. Ó 2009 Elsevier Inc. All rights reserved. 1. Introduction The fruitfly Drosophila melanogaster is model organism that has been extensively used for aging research (see review Baker and Mokrynski, 1989; Boulianne, 2001; Helfand and Rogina, 2003; Tower, 1996). Using a variety of different approaches, investigators have been able to take advantage of the short life-span of the fly (normally 60–80 days) to determine the effect of genetic and envi- ronmental factors including mating status and genotype (Malick and Kidwell, 1966), dietary restriction (Chippindale et al., 1993) and restricted mating (Chapman et al., 1995) on life-span. Recent advances in Drosophila genetics and molecular biology have also made it possible to identify genes and pathways that have a pro- nounced effect on longevity. Among them are, Indy, which func- tions as an exchanger for Krebs cycle intermediates (Rogina et al., 2000) and mth, which shares homology with several guano- sine triphosphate-binding protein-coupled receptors (Lin et al., 1998). In addition, several studies have shown that both Inr and chico, components of the insulin-like signaling pathway (Clancy et al., 2001; Tatar et al., 2001) also play an important role in organ- ismal life-span. Finally, several studies have shown that tissue-spe- cific overexpression of specific genes, and in particular, those involved in oxidative stress resistance, can also extend life-span (Parkes et al., 1998; Sun et al., 2002). However, despite the progress made in Drosophila aging re- search during the last decades, many longevity studies have often yielded controversial results that can be attributed to differences both in genetic background and in experimental design (Le Bourg and Minois, 2005; Lints et al., 1983; Orr and Sohal, 2003). For example, the data were often obtained under a variety of experi- mental conditions, using different sample sizes and different sta- tistical strategies that often make it difficult to make valuable comparisons and conclusions between experiments, even when studying the same gene mutations (Tatar, 2005; Toivonen et al., 2007). Here, we describe the results of a systematic analysis of life-span comparisons in two laboratory wild-type strains: Canton S (CS) and Oregon R (OR). The main goal of these studies is to clar- ify the effects of social status, mating and sex on life-span in CS and OR flies with the aim of defining the optimal experimental design whereby the influence of these factors would be mini- mized. These results may be especially important for screens de- signed to search for genes that may be involved in longevity as well as for comparative analysis of strains in which the genetic background is unknown or in those cases where it is very difficult to equilibrate. 0531-5565/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.exger.2009.05.008 * Corresponding author. Address: Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, 101 College Street, East Tower, Room 12-305, Toronto, Ont., Canada M5G 1L7. Tel.: +1 416 813 8701; fax: +1 416 813 2212. E-mail address: gboul@sickkids.ca (G.L. Boulianne). Experimental Gerontology 44 (2009) 546–553 Contents lists available at ScienceDirect Experimental Gerontology journal homepage: www.elsevier.com/locate/expgero