My research is based on environmental insults and the role they play in the stress physiology of insects using the phenomena known as hormesis. The positive or negative biphasic response that occurs in the presence of mild stress is hormesis. Hormesis can be protective as a multifarious response that results in upregulation of genes and organismal performance. This multifarious response refers to the many responses that can occur simultaneously as animals age. The response of said genes are in reference to the organism’s natural ability to protect itself from abiotic and biotic stressors. The protective effects of hormesis in animal models includes improved survival, mating, extended longevity, and improved performance at old age (i.e. mating); amongst others (Chapter 2). I observe responses from UVA (Chapter 3), Anoxia and Gamma radiation (Chapter 4), and Heat (Chapter 5) in insects Drosophila Melanogaster and Cimex lectularius. The sun is a source of energy used by terrestrial life in many trophic levels allowing for exposure to irradiation (UVR), a natural environmental stressor that increases production of reactive oxygen species (ROS). This type of environmental stress is damaging by attacking lipids, proteins and DNA. Exposure to prolonged UVR conditions early in life (pupae) leads to changes in performance later in life. This response can be classified as preconditioning, pretreatment, conditioning, or cross tolerance. Previous studies scantily provide appropriate levels of exposure needed for UVR hormesis that would increase production of ROS and antioxidant enzymes. The age of the individual at the time of treatment can have dramatic effects on hormesis with low dose UVR effects that induce protection, an extension of normal life span and improved organismal performance shown in other insects (Calabrese 2013). The vinegar fly, Drosophila melanogaster, was exposed to UVA at different intensities. Vials containing pupae, separated from food and kept in same vial were exposed to 0, 30, 45 or 60 minutes of ultraviolet radiation A (nm = 365). Different rates of UVA exposure (mW/m2), produced by the distance from the source, show slight differences in treatment survival/adult emergence and flight ability. My data show cellular protection that occurs from doses of direct stress that do not induce mortality, aiding in the Preparation for Oxidative Stress (POS) hypothesis (Hermes-Lima et al., 1998; Hermes-Lima and Zenteno-Savıń , 2002; Giraud-Billoud et al., 2019). This hypothesis is defined by the preparation or the pre-conditioning that occurs when boosting cellular defenses through applied stress early in life. Low doses of UVR lead to protective and beneficial responses, while exposures to high doses are damaging and detrimental. The experimental data fills knowledge gaps on my intentions of finding the cost associated with hormesis as an adaptive response. Ultimately, data such as these can be refined to develop a model of dose response that can be used to estimate hormesis, or the biphasic response.
|Commitee:||Unguez, Graciela , Lopez-Martinez, Giancarlo, Pichon, Henrietta , Cooke, Peter|
|School:||New Mexico State University|
|School Location:||United States -- New Mexico|
|Source:||DAI-B 82/7(E), Dissertation Abstracts International|
|Subjects:||Biology, Molecular biology|
|Keywords:||Drosophila melanogaster, Entomology, Hormesis, Oxidative damage, Reactive oxygen species, Ultraviolet radiation|
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