Comparing Minimally Lethal Sampling Methods for Genomics in the Eastern Oyster (Crassostrea virginica)

Area of Science:

• Aquaculture
• Genetics
• Marine Biology

Background:

• Genotyping individual organisms is crucial for understanding selection and survival, especially in aquaculture species like the Eastern oyster (Crassostrea virginica).
• Obtaining high-quality DNA from mollusks without causing significant mortality presents a persistent challenge in research and selective breeding programs.

Purpose of the Study:

• To identify an optimal, minimally invasive method for collecting high-quality DNA from Eastern oysters (Crassostrea virginica) while minimizing post-sampling mortality.
• To evaluate various combinations of cell accession, sampling, and preservation techniques for their efficacy in DNA yield and impact on oyster survival.

Main Methods:

• Tested nine treatment groups combining two accession techniques (relaxation, shell notching), four cell sampling methods (swab, mantle biopsy, hemolymph, extrapallial fluid), and three preservation methods (flash freezing, ethanol, FTA card).
• Monitored oyster mortality for 11 days post-sampling and quantified DNA quantity and quality across all treatment groups.

Main Results:

• Mantle biopsies from relaxed oysters preserved in ethanol yielded DNA quantities comparable to controls and significantly higher than liquid samples.
• This optimal method demonstrated low post-sampling mortality, with oysters >61mm having a >90% survival chance.
• The chosen method balances DNA yield and quality with minimal impact on oyster survival.

Conclusions:

• Established a viable method for genotyping juvenile Eastern oysters (Crassostrea virginica) that significantly minimizes post-sampling mortality.
• This method will support future research in genomic selection, individual survival responses to environmental stressors, and gene expression studies in mollusks.
• Facilitates long-term studies requiring repeated genetic sampling and survival monitoring in aquaculture settings.