Morphological and DNA analysis in human skeletal remains exposed to environmental conditions in Brazil

Abstract Investigations of genetic kinship and human identification through DNA analysis of human skeletal remains have been required for several types of cases. A molecular study of this kind of sample is a challenge because of the small amount of cells available. In Brazil, there is a dominating humid tropical climate which can exert a direct influence on the microscopic morphology of bones and consequently on the DNA. The objective of this study was to analyze the microstructure of femoral compact bone tissue samples that were exposed to harsh environmental conditions in Brazil, correlating it with the amount of human DNA extracted. Compact bone fragments were used from femoral diaphysis of 20 skeletonized corpses found in the period 1998–2009 in Ribeirao Preto, Sao Paulo, Brazil. Samples were processed, stained with H&E and from the densest cellular area, 10 consecutive fields were selected by a pathologist and software Image Tool (UTSCH-USA) and Image J (NHI-USA) were used for cellular analysis. DNA extraction was performed through commercial kit and quantification with Quantifiler Duo DNA kit (Applied Biosystems). Osteocytes were observed in all cases ranging from 1 to 40 and DNA amount was correlated with the morphology observed. These results indicate preservation of osteocytes in bone material exposed to tropical environmental conditions, signifying the feasibility of obtaining DNA for genetic studies. A preliminary morphology analysis in skeleton samples can predict success in extracting DNA from these samples, since a significant correlation was found between these two variables.