Mitochondrial DNA and STR analyses of maggot crop contents: effect of specimen preservation technique

Abstract

DNA analysis of maggot crop contents can be used to identify a missing body or aid entomologists with interpreting evidence used for PMI estimations. Entomological evidence is often collected and preserved to keep identifiable external features intact. The preservation methods currently in use may not be suitable for preserving DNA in the maggot crop for later analysis. In this study, carrion maggots raised on human tissue were preserved under the following 8 preservation conditions: no fluid at -70 degrees C, no fluid at 4 degrees C, no fluid at 24 degrees C, 70% ethanol at 4 degrees C, 70% ethanol at 24 degrees C, 95% ethanol at 24 degrees C, Kahle's solution at 24 degrees C and formaldehyde at 24 degrees C. Maggots were dissected following 2 weeks, 8 weeks and 6 months of preservation. The maggot crops were extracted, human DNA was quantitated, and an attempt was made at amplifying mitochondrial DNA (mtDNA) and short tandem repeat (STR) loci. Both mtDNA and STRs were successfully amplified from maggots stored in ethanol or without any preservation fluid. Formalin-containing preservation solutions reduced the recovery of DNA. The best results were observed from maggots stored without any preservation fluid at -70 degrees C.