Comparative study of the efficiency of ethanol 95% and salt-saturated dimethyl sulfoxide preservatives on quality and quantity of DNA extracted from soft tissues

Background: Preparation of the purified and high molecular weight DNA is considered as a first step in tissue molecular analysis. Optimization of the conditions at which samples are received as duration, temperature and preservative agents used is important to avoid affecting the quantity and quality of the extracted DNA. Aim of the work: comparing the efficiency of two DNA preservatives agents [ethanol 95% and salt-saturated dimethyl sulfoxide (SSDMSO)] on the extracted DNA from soft tissues and specifying which of the two studied organs (kidney and heart) gives better DNS yield after preservation at room temperature and at -20ºC. Materials and methods: The study was done on 19 autopsy cases. 300 mg of each selected soft tissues (kidney and heart) were preserved as follow: In 2 ml sterile water (Control group), at -20°C (Freezing group), Ethanol 95% (Ethanol group) and in SSDMSO (SSDMSO group). After DNA extraction, DNA quantity was measured using NanoDrop method while DNA quality was measured using agarose gel electrophoresis. Results: All preservatives could retain DNA up to the two months. SSDMSO gave the highest DNA concentration followed by Ethanol 95%. The superiority to heart tissues in SSDMSO preservative over kidney tissues in both Ethanol 95% and SSDMSO preservatives up to two months. Conclusion: It is concluded that SSDMSO is a successful preservative agent, and it is superior to ethanol 95% for preservation of DNA in soft tissues up to two months at room temperature. Heart tissue is less susceptible to degradation and hence more suitable for DNA fingerprinting than kidney tissue. Recommendations: It is recommended to use SSDMSO as preservative for soft tissue collected for DNA analysis and to choose the heart for sampling.