Long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for fish growth, development, and overall health, particularly during early life stages. As fish oil is increasingly replaced in aquafeeds with sustainable plant-based alternatives, understanding the endogenous LC-PUFA biosynthetic capacity of marine aquaculture candidates is critical for selecting species capable of efficiently utilizing alternative ingredients while maintaining growth, development, and fillet quality. Although historically considered limited in marine fish, recent studies demonstrate that some marine teleosts retain significant biosynthetic capacity, shaped by habitat, trophic ecology, and evolutionary history (Garrido et al., 2019; Xie et al., 2021; You et al., 2024; Zhao et al., 2024).
This study evaluates the LC-PUFA biosynthetic potential of red drum (Sciaenops ocellatus), red snapper (Lutjanus campechanus), and common snook (Centropomus undecimalis), three commercially important and promising aquaculture species in Florida. Total RNA was extracted from red drum and red snapper larvae, and from snook liver tissue, using the Zymo Research Mini RNA Isolation Kit™, following the manufacturer’s protocol. RNA integrity and concentration were assessed via gel electrophoresis and spectrophotometry (NanoDrop ND-2000C, Thermo Fisher Scientific). First-strand cDNA synthesis was performed using 1 µg of total RNA. Species-specific primers targeting the fads2 gene were designed based on conserved teleost sequences.
PCR amplification of fads2 from red drum was carried out under the following conditions: initial denaturation at 94°C for 3 min; 35 cycles of 98°C for 30 s, 58°C for 30 s, and 72°C for 45 s; followed by a final extension at 72°C for 5 min. The amplified fragments were cloned into the pYES2 yeast expression vector for functional characterization.
Preliminary functional assays indicate that S. ocellatus expresses a bifunctional Δ6/Δ8 desaturase (fads2), suggesting a limited endogenous capacity for LC-PUFA biosynthesis. Functional characterization of fads2 from L. campechanus and C. undecimalis is currently ongoing and will provide further insight into the LC-PUFA biosynthetic capabilities of these species.