Development of a sandwich hybridization assay for the identification of red drum, Sciaenops ocellatus, eggs: A novel tool for fishery research and management
Mortensen, Rebecca Anne
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Egg identification and quantification are crucial to understanding the spawning and recruitment dynamics of economically important fish species. This study describes the development of a novel molecular method for finfish egg identification that eliminates the need for time-consuming microscopy. Sandwich hybridization assay (SHA) uses two ribosomal RNA (rRNA)-targeted oligonucleotides to directly detect unpurified and unamplified rRNA. Probes were designed to compliment the internally transcribed spacer (ITS) region of the red drum, <i>Sciaenops ocellatus</i>, an important recreational gamefish for which spawning and reproductive information is sparse. Sample homogenization procedures were modified to disrupt egg chorion, and the resultant assay detected <i>S. ocellatus</i> eggs and tissues without cross-reactivity. Standard curves were linear (Y<sub>450</sub> = 0.001x + 0.054; R<sup>2</sup> = 0.999), showing potential for quantitative uses, and the lower limit of detection was 5 eggs mL<sup>-1</sup> homogenate. Ontogenetic stage had a significant effect (ANOVA, <i>p</i> < 0.05) on optical density. The assay successfully detected S. ocellatus eggs in field samples from Charleston Harbor, South Carolina, and could be incorporated into current management practices or adapted to other species.