Oxidative damage results from the inability of an organism to cope with reactive oxygen species (ROS) that are formed as byproducts of metabolism. Damage to various classes of biomolecules has been implicated in cellular senescence, aging and debilitating diseases. This research will be the first to address the effects of multiple aspects of oxidative damage on fitness-related measures in a free-living long-lived avian model. The framework currently being developed from this research may be of importance to the medical community as birds are increasingly being recognized as viable models to assess adaptations to combat oxidative damage, senescence, and associated diseases in humans. Florida Scrub-Jays will be used to assess whether the accumulation of oxidative damage negatively affects reproductive decisions and output, as well as fitness. Both nestling and adult birds will be supplemented with antioxidants which neutralize ROS. Thus, birds that receive antioxidants are predicted to demonstrate higher reproduction and survivorship. Florida Scrub-Jays are a federally threatened species and therefore, the results of this research may be applied broadly to assist in the conservation of this, and other threatened species by providing important clues as to the best management practices with regard to supplemental antioxidant diets. Additionally, through collaboration with Archbold Biological Station (ABS), an ecological research facility intimately involved in environmental education, this research will integrate scientific advancement with educational opportunities. This research will be published in high profile journals and presented at scientific and lay meetings. It will also be shared informally through interactions with visitors to ABS, and formally both through the station?s internship program which brings several dozen undergraduate and graduate students to the station to work on independent projects each year and the ABS ecology education program which hosts nearly 3,000 3rd-5th grade schoolchildren every year.

Project Report

Oxidative damage has been increasingly identified as an integral contributor to many of today’s most prevalent and debilitating diseases including cardiovascular (Madamanchi et al. 2005), Parkinson’s (Zhang et al. 1999) Alzheimer’s (Ding et al. 2007), numerous types of cancer (Oberley 2002), and many others (see Singh 2006). Basic research in non-traditional organisms, such as birds, may play an important role in understanding and combating these diseases in humans. A convincing body of evidence suggests that birds, as long-lived animals, possess many adaptations to combat oxidative damage and associated senescence and, as such, are a better model for these issues in humans than are the relatively short-lived rodent models that are typically employed (Holmes et al. 2001; Holmes & Ottinger 2003). A recent investigation in Florida Scrub-Jays (FSJ: Aphelocoma coerulescens) has provided considerable information on the physiology of aging (Schoech & Wilcoxen, NSF DDIG: IOS-0909620; Wilcoxen et al. 2010). We built upon this foundation by exploring whether levels of oxidative damage or resistance to such damage influence reproductive behaviors, growth and development and survivorship in a free-living bird. Previous research on these topics has largely been limited to lab-based studies that have assessed limited indicators of oxidative stress (e. g., antioxidant level, reactive oxygen species (ROS) level, or ROS resistance). Our research demonstrated the significant importance of the use of multiple measures for oxidative status, as we report no consistent correlations between several measures currently being used to assess oxidative status. We also report that oxidative cost of reproduction was sex specific with pre-breeding oxidative damage levels negatively correlated with reproductive effort only in males. Similarly, in males, post-breeding levels of oxidative damage were significantly greater than pre-breeding levels. Supplementation with antioxidants did not significantly change reproductive effort, or affect post-breeding oxidative damage levels. However, there was a relationship between change in oxidative damage levels with reproductive effort and treatment group (i. e., supplemented with antioxidants or not). Further, males that lost mass during the breeding season also exhibited decreased levels of oxidative damage from pre- to post-breeding. Supplementation of nestlings did not significantly affect growth or oxidative damage measures. Oxidative damage to proteins was significantly lower in older individuals, whereas Total Antioxidant Capacity was significantly higher in older individuals; however, damage to DNA did not significantly differ across ages. Oxidized proteins increased significantly from the nestling to nutritional independence stages (~2 months of age) and then subsequently declined as birds reached ~9 months of age. There were no relationships between oxidized proteins and survival at these early life stages During the course of this research, co-PI, RSH, gained valuable training for her graduate career which she will continue to use in her professional career. Additionally, she served as a mentor to six interns working at Archbold Biological Station; an ecological research facility intimately involved in environmental education. She was also able to train an undergraduate attending the University of Memphis in laboratory techniques including several of the oxidative stress assay protocols which he will use as he is conducting independent research over the course of the next few years of study at Memphis. This research was presented at multiple national and international forums. Including the 2012 Society for Integrative and Comparative Biology meeting and the 2012 North American Ornithological Conference. Additionally, this research resulted in a publication in Phsyiological and Biochemical Zoology (Heiss & Schoech 2012), and a second article is under review at the same journal.

National Science Foundation (NSF)
Division of Integrative Organismal Systems (IOS)
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Michelle M. Elekonich
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University of Memphis
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