Studying the Role of Soil Factors on DNA Profiles of Human Remains
Abstract
The generation of DNA profiles from skeletal remains is an important part of the identification process in both mass disaster and unidentified person cases. Since bones are the best biological materials remaining after exposure to soil factors and other environmental conditions and in cases where many years have passed since the of the individual,s death, the ability to purify large quantities of informative DNA from these hard tissues would be beneficial. Methods: Seventy femur male bone samples were collected from two different environmental mass graves (Al-Mahawiel mass grave) in Babil governorate and (Wadi Al-Salam mass grave) in Al-Najaf governorate in Iraq. The DNA from bone sample extracts was assessed by capillary electrophoresis and a standardized set of short tandem repeat (STR) loci were analyzed using Mutiplex 21 STR loci System to allow human identification by matching the profile of the dead individuals with their relatives. From these two different sites; soil samples were collected to analyze and study the different environmental factors and find a relation between the degree of preservation or degradation with factors like temperature, humidity, salinity, PH and texture of soil and find how these factors can affect on pattern of degradation of DNA profiles. Results: average of the percentage of the detected alleles in each locus in the two sites; was 87% for the Al-Mahawiel site and 71% for the Al-Najaf site. PH was 8.2 for the Al-Mahawiel site soil where as pH was 8.1 for Al-Najaf site soil. The Humidity in the clay soil of the Al-Mahawiel site was7.5% while it was 3.5% for the sandy soils in Al- Al-Najaf site. The total soluble salts were 1.9% in clay soil of the Al-Mahawiel site, while it was 24.1% in Al -Najaf sandy soil. Conclusion: clay soil, low salt concentration, PH slightly alkaline and low humidity all participated in increasing DNA preservation in the Al-Mahawiel site while the sand soil and high salt concentration participated in increasing DNA degradation in the Al -Najaf site.
