DNA degradation in fish: practical solutions and guidelines to improve DNA preservation for genomic research

Abstract

1) The more demanding requirements of DNA preservation for genomic research can be difficult to meet when field conditions limit the methodological approaches that can be used, or cause samples to be stored in suboptimal conditions. Such limitations may increase rates of DNA degradation, potentially rendering samples unusable for applications such as genome-wide sequencing. Nonetheless, little is known about the impact of suboptimal sampling conditions. 2) We evaluated the performance of two widely used preservation solutions (1. DESS: 20% DMSO, 0.25M EDTA, NaCl saturated solution, and 2. ethanol) under a range of storage conditions over a three-month period (sampling at 1 day, 1 week, 2 weeks, 1 month, and 3 months) to provide practical guidelines for DNA preservation. DNA degradation was quantified as the reduction in average DNA fragment size over time (DNA fragmentation) because the size distribution of DNA segments plays a key role in generating genomic datasets. Tissues were collected from a marine teleost species, the Australasian snapper, Chrysophrys auratus. 3) We found that the storage solution has a dramatic effect on DNA preservation. In DESS, DNA was only moderately degraded after three months of storage while DNA stored in ethanol showed high levels of DNA degradation already within 24 hours, making samples unsuitable for next-generation-sequencing. 4) We recommend DESS as the most promising solution to improve DNA preservation. These results provide practical and economical advice to improve DNA preservation when sampling for genome-wide applications. Keywords: DMSO, DNA preservation, ethanol, fish, next-generation-sequencing, NGS, snapper