A Novel Ex Vivo Approach Based on Proteomics and Biomarkers to Evaluate the Effects of Chrysene, MEHP, and PBDE-47 on Loggerhead Sea Turtles (Caretta caretta)

Abstract

The principal aim of the present study was to develop and apply novel ex vivo tests as an alternative to cell cultures able to evaluate the possible effects of emerging and legacy contaminants in Caretta caretta. To this end, we performed ex vivo experiments on non-invasively collected whole-blood and skin-biopsy slices treated with chrysene, MEHP, or PBDE-47. Blood samples were tested by oxidative stress (TAS), immune system (respiratory burst, lysozyme, and complement system), and genotoxicity (ENA assay) biomarkers, and genotoxic and immune system effects were observed. Skin slices were analyzed by applying a 2D-PAGE/MS proteomic approach, and specific contaminant signatures were delineated on the skin proteomic profile. These reflect biochemical effects induced by each treatment and allowed to identify glutathione S-transferase P, peptidyl-prolyl cis-trans isomerase A, mimecan, and protein S100-A6 as potential biomarkers of the health-threatening impact the texted toxicants have on C. caretta. Obtained results confirm the suitability of the ex vivo system and indicate the potential risk the loggerhead sea turtle is undergoing in the natural environment. In conclusion, this work proved the relevance that the applied ex vivo models may have in testing the toxicity of other compounds and mixtures and in biomarker discovery.

Immunity in Sea Turtles: Review of a Host-Pathogen Arms Race Millions of Years in the Running

“…The dramatic increase in FP prevalence since the 1980s is attributed to a virus, and an unknown environmental factor thought to be anthropogenic in nature [68][69][70]. Results from genomic [71], proteomic [72][73][74] and transcriptomic studies [70,75,76] have consistently identified immune genes as dysregulated between healthy and diseased turtles or by levels of exposure to marine contaminants [73]. Additionally, sea turtles are possible reservoirs for zoonotic viruses, as C. mydas, along with snakes and pangolins, have been suggested as potential intermediate hosts of SARS-CoV-2 [77].…”

“…Studies of sea turtle immune function have been focused on the protection and conservation of turtle wildlife from threats such as FP, parasites, or environmental contaminants [42,[49][50][51][52][53][54][55][56]73,75,76,[88][89][90][91][92]. Functional studies of the turtle immune system have been carried out on red-eared slider turtles Trachemys scripta (Thunberg, 1792)) [19][20][21][22][23], Caspian turtle or striped-neck terrapin (Mauremys capsica (Gmelin, 1774)) [27][28][29][30][31] and Chinese softshelled turtle (Pelodiscus sinensis (Wiegmann, 1853)) [14,87,87,93].…”

“…The results are unique as serum complement pathways are assumed to be conserved within clades and highlight the need for avoiding the generalization of immune functions between turtle species [61]. Regarding sea turtles, complement proteins (C3, C4, C5) have been highlighted as a poten-tial biomarker of C. caretta [38] and C. mydas [73] health when recovering in rehabilitation facilities as they serve as good indicators of stress, infection, or exposure to pollutants.…”

“…Acute phase proteins have been measured in investigations for potential uses as biomarkers of immune response in C. mydas [73,74] and C. caretta [38,39]. Chaousis et al employed a mass-spectrometry-based non-targeted proteomics approach and highlighted its potential for biomarker discovery in wildlife toxicology [73].…”

“…Acute phase proteins have been measured in investigations for potential uses as biomarkers of immune response in C. mydas [73,74] and C. caretta [38,39]. Chaousis et al employed a mass-spectrometry-based non-targeted proteomics approach and highlighted its potential for biomarker discovery in wildlife toxicology [73]. In this comparison study of green sea turtles from three different foraging sites in Australia, seven acute phase proteins were highly dysregulated; Alpha-1-antitrypsin, Alpha-2-macroglobulin-like, Ceruloplasmin, Complement C4, Complement factor, fibrinogen alpha chain, and haptoglobin [73].…”