n-3 polyunsaturated fatty acids (n-3 PUFAs), including eicosapentaenoic acid (EPA), are essential nutrients for vertebrate development and physiology. Microorganisms, such as microalgae, produce n-3 PUFAs that are transferred to higher predators in the aquatic food web. However, recent studies have demonstrated that various aquatic invertebrates possess the biosynthetic enzymes required for n-3 PUFA production, raising the possibility that n-3 PUFAs are also produced in certain aquatic invertebrates. In contrast to aquatic invertebrates, it remains unclear whether and how PUFAs are produced in terrestrial invertebrates, including collembolans, one of the most widespread microarthropods in soil ecosystems. In this study, we investigated the biosynthetic capacity of n-3 PUFAs in litter-dwelling Collembola, Sinella dubiosa. We detected EPA in Sinella dubiosa reared on Brewer's yeast, which produced only saturated and monounsaturated fatty acids. Furthermore, metabolic analysis using isotope-labeled fatty acids revealed that oleic, linolenic, and arachidonic acids were metabolized to EPA in Sinella dubiosa. Given that collembolans are food for predatory arthropods and their nutrients are transferred to higher predatory vertebrates in the soil food web, we propose that Collembola serve as an EPA source in soil ecosystems.
Keywords: Collembola; EPA; PUFA; Sinella dubiosa.
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