The molecular weight of the extracted DNA was determined by running 2 μL of each sample in 0.8% agarose gel, 1× TAE buffer (Thermo Fisher Scientific) for 4 h at 60 V. The DNA was stained with 1× SYBR safe (Invitrogen, Waltham, Massachusetts, USA). The molecular weight of the genomic DNA was estimated by comparison with a HMW DNA ladder (Lambda DNA/EcoRI+HindIII; Thermo Fisher Scientific). Digital images of the gels were generated in an Amersham 600 RGB imager (GE Healthcare, Chicago, Illinois, USA) using automatic collection parameters. The images of the gels were enhanced (contrast, homogenization, and background removal) in ImageJ version 1.52a (Rasband, 2018 ) prior to the digital analysis. The 1D gel electrophoresis image analysis software GelAnalyzer2010a (http://www.gelanalyzer.com ) was used to create profiles of the distribution of DNA fragments (Fig. 2 A, B) using the Lambda DNA/EcoRI+HindIII DNA ladder as a size reference.
For all species, HMW DNA was exclusively observed in the DNA samples extracted from cells homogenized using the LN2 grinding method. The DNA extracted using this treatment was observed as a tight, clear band over the 21.2‐kbp marker band, whereas DNA extracted from cells homogenized using the other treatments displayed substantial smearing and lacked a clear HMW DNA band, consistent with high DNA fragmentation (Fig.2 ).
For all species, HMW DNA was exclusively observed in the DNA samples extracted from cells homogenized using the LN2 grinding method. The DNA extracted using this treatment was observed as a tight, clear band over the 21.2‐kbp marker band, whereas DNA extracted from cells homogenized using the other treatments displayed substantial smearing and lacked a clear HMW DNA band, consistent with high DNA fragmentation (Fig.