Identifying biomarkers of pollutant exposure in ocean sentinels: Characterisation and optimisation of B-esterases in plasma from loggerhead turtles undergoing rehabilitation

Sea turtles are frequently proposed as indicator species for assessing ocean health. To faciliate the use of these species as bioindicators requires the development of tools for rapidly and effectively assessing individual health. Here, we collected 104 blood samples from 69 loggerhead sea turtles,...

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Bibliographic Details
Published in:Chemosphere (Oxford) 2024-01, Vol.348, p.140770-140770, Article 140770
Main Authors: Omedes, S., Crespo-Picazo, J.L., Robinson, N.J., García-Párraga, D., Sole, M.
Format: Article
Language:English
Subjects:
Carboxylesterases
Caretta caretta
Cholinesterases
Marine litter
Plastic additives
Sea turtles
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Summary:Sea turtles are frequently proposed as indicator species for assessing ocean health. To faciliate the use of these species as bioindicators requires the development of tools for rapidly and effectively assessing individual health. Here, we collected 104 blood samples from 69 loggerhead sea turtles, Caretta caretta, undergoing rehabilitation to determine the connection between health status, the activity of B-esterases, and other biochemical parameters. To determine the optimal assay protocol for B-esterases, we measured the activity and kinetics of cholinesterases-(ChEs) and carboxylesterases (CEs) using 3 and 5 commercial substrates, respectively, at different assay conditions. IC50 values for the activity of B-esterases were calculated within a concentration range for model pesticide inhibitors. Turtles’ health status was determined via routine veterinary procedures. During rehabilitation (which was associated with improving health status), we observed a decrease in the activity of most enzymes (especially in acetylcholinesterase) alongside an increase in CE when using p-nitrophenyl acetate as a substrate. As such, it is possible that the activity rates of plasmatic B-esterases could serve as an indicator of health status. There is also high potential that B-esterases could be specifically sensitive to marine pollutants although to further validate this would require future studies to specifically correlate B-esterarse activities to pollutant concentrations in blood or excreta. [Display omitted] •Loggerhead turtles undergoing rehabilitation exhibited a decrease in plasmatic AChE activity.•Increases in pNPA-CE activity in loggerhead turtles may be linked to immune-system modulation.•Higher hydrolysis rates on plasmatic B-esterase measurements in marine turtles were seen at pH = 8.•Gas embolism significantly affected αNB-CE measurements in marine turtles.
ISSN:0045-6535
1879-1298
DOI:10.1016/j.chemosphere.2023.140770