Inhibition of DNA Amplification in Marine Fish Larvae Preserved in Formalin

Abstract

Recent advances in molecular biology open the possibility to use formalin-preserved specimens stored in ichthyoplankton collections for population genetics studies. Nine DNA extraction techniques were tested on Engraulis mordax larvae preserved in buffered formalin. However, none of the DNA extracts resulted in the positive amplification of mitochondrial DNA (mtDNA) (NADH1, 16srRNA, 12srRNA and control region fractions). An experiment with different length-time exposure to formalin done with Cynoscion parvipinnis larvae allowed us to confirm the difficulty of amplifying mtDNA from larvae preserved in formalin for long time periods and the possibility of DNA extraction and amplification from short-term (less than 48 h) formalin-fixed marine fish larvae preserved in ethanol (70%). We discuss the possible influence of physical–chemical complexes associated with the duration of preservation to inhibition of amplification reactions.