Inhibition of DNA amplification in marine fish larvae preserved in formalin

Recent advances in molecular biology open the possibility touse formalin-preserved specimens stored in ichthyoplankton collectionsfor population genetics studies. Nine DNA extraction techniqueswere tested on Engraulis mordax larvae preserved in bufferedformalin. However, none of the DNA extracts resulted in thepositive amplification of mitochondrial DNA (mtDNA) (NADH1,16srRNA, 12srRNA and control region fractions). An experimentwith different length-time exposure to formalin done with Cynoscionparvipinnis larvae allowed us to confirm the difficulty of amplifyingmtDNA from larvae preserved in formalin for long time periodsand the possibility of DNA extraction and amplification fromshort-term (less than 48 h) formalin-fixed marine fish larvaepreserved in ethanol (70%). We discuss the possible influenceof physical–chemical complexes associated with the durationof preservation to inhibition of amplification reactions.