DNA sequencing of formalin-fixed crustaceans from archival research collections

Marine invertebrate collections have historically been maintained in ethanol following fixation in formalin. These collections may represent rare or extinct species or populations, provide detailed time-series samples, or come from presently inaccessible or difficult-to-sample localities. We tested the viability of obtaining DNA sequence data from formalin-fixed, ethanol-preserved (FFEP) deep-sea crustaceans, and found that nucleotide sequences for mitochondrial 16S rRNA and COI genes can be recovered from FFEP collections of varying age, and that these sequences are unmodified compared with those derived from frozen specimens. These results were repeatable among multiple specimens and collections for several species. Our results indicate that in the absence of fresh or frozen tissues, archived FFEP specimens may prove a useful source of material for analysis of gene sequence data by polymerase chain reaction (PCR) and direct sequencing.