Collaborative Research: Red carotenoids as signals of respiratory chain function

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

Carotenoid pigments are among the most common colorants in nature. They provide coloration to many animals, and carotenoid coloration has long been documented to be a reliable signal of individual health and vitality. The basis for this connection between color display and individual quality (or fitness) remains speculative. This NSF-sponsored project will test the hypothesis that production of red pigments is tied to core energy production in the powerhouse of the cell- the mitochondrion. For this study, researchers will study wild-caught copepods, Tigriopus californicus, which are a type of tiny shrimp with red coloration that they derive by altering yellow dietary carotenoids to red pigments. Evidence suggests that this conversion takes place in the mitochondrion. The authors will use genetic and chemical treatments to disrupt cellular respiration and measure the effect on red coloration. Establishing carotenoid coloration as a signal of mitochondrial function has important practical implications. If carotenoid coloration is a signal of mitochondrial function, then it could be used for environmental monitoring. Carotenoids are also widely distributed as health supplements with possible benefits in fighting cancer, macular degeneration, and even aging. Understanding the mechanisms of carotenoid use and distribution in non-human animals will help inform their use as health supplements in people. Copepods also present an ideal system in which to engage grade-school students in science and through outreach programs we will use experiments showing the diet dependency of copepods to engage young people in the process of science. Carotenoids are common components of living systems, playing key roles in free radical scavenging and production of yellow, orange, and red coloration. Despite extensive research showing that carotenoid coloration is dependent on an animal's condition and is sensitive to environmental perturbations, the mechanisms that link carotenoid coloration to condition and health remain poorly understood. This project will test the hypothesis that production of carotenoid-based red coloration in animals is intimately tied to electron transport system (ETS) function. Tigriopus californicus (TC copepods) have red coloration that they derive by oxidizing yellow dietary carotenoids through the same pathways used by vertebrates that display red coloration. Tightly controlled experiments using TC copepods will test the effects of hybrid-induced ETS dysfunction on the production of red coloration. Chemical treatments that target specific components of the ETS will be used to dissect the specific mechanisms underlying the linkage between mitochondrial function and carotenoid metabolism. If ornamental coloration is dependent on the mitochondrial membrane potential and closely linked to ATP production, then carotenoid coloration signals something fundamental about an animal. Moreover, if production of red carotenoid coloration depends on the fundamental health and functionality of an animal, then humans can assay the health and condition of individual animals and populations of animals by quantifying red coloration. Copepods also present an ideal system in which to engage grade-school students in science. Through outreach programs, experiments will be used to show the diet dependency of copepods and to engage young people in the process of science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.