Effect of in vitro Incubation Time and Drying on Genomic DNA Extracted from Bovine Ear Tissue Samples

Abstract

Background: Use of ear punch samples as a competent source of nucleic acids from bovines, gained momentum around two decades ago, as their collection is quite easy and can be transported with minimal quantities of preservatives at ambient conditions. However, the auricular cartilage makes them more resistant to lysis, resulting in poor genomic DNA yields. The objective of the current study was to investigate whether drying can enhance the gDNA yields from ear tissue samples as a few past experiments gave an unanticipated good gDNA yields from completely dried tissue samples. Methods: Upon receipt, ear tissue samples of the cattle and buffaloes were kept at room temperature for different time intervals (in vitro incubation) and then dried at various temperatures prior to gDNA extraction, with commercially available gDNA extraction kits from two manufacturers (MN and QIAGEN). The extracted gDNA samples were assessed with spectrophotometry, flourometry and agarose gel electrophoresis for concentration, purity and integrity. Result: gDNA yields were gradually increasing in parallel to in vitro incubation time till 250 days and after that there was a decline. Further, gDNA yields were significantly higher for ear tissue samples that were not dried prior to extraction, which did not comply with the past experimental observations. Fluorometry-based quantifications revealed that drying of ear tissue samples at greater than 50°C temperatures reduced double-stranded DNA, however up to 50°C the gDNA yield increased, indicating the tissue samples can be safely transported up to 50°C in the TSUs.