Decoding sex-specific metabolomic biomarkers in the loggerhead sea turtle (Caretta caretta)

There is need for advancing minimally invasive diagnostic techniques for sex differentiation at early life-stage classes in sea turtles. The objectives of this study were to determine whether there are sex-specific effects on the metabolome of the loggerhead sea turtle (Caretta caretta) and to identify potential biomarkers for sex classification at early life-stage classes (50 post-hatchling and 50 juvenile). Comprehensive analyses including plasma chemistry (n = 100) and untargeted (n = 48) metabolomic analyses were performed. Unlike with plasma chemistry analytes, there were significant differences in the metabolomic profiles between sexes. Nine metabolites differed significantly between sexes, with several metabolites deserving greater attention as potential biomarkers: C₂₂H₃₂O₆ and pantothenic acid was higher in females than in males, and carboxylic acid ester (C₁₀H₁₆O₅), 1-methylhistidine and C₇H₁₄N₂O₇ was higher in males than females. These differences remained constant both across and within the same life-stage class. This work identified a discernible effect on the metabolic profile based on sex of loggerhead sea turtles and it suggests that these metabolites and/or their ratios could serve as potential biomarker candidates for sex classification in this species.