Discussion on Freezing and Thawing Does Not Affect Genome Integrity of Germ Cells

Normally freeze-thaw causes damage to DNA but germ cells stored in refrigerator showed minimal
damage in a structure, as the DNA freeze-thawed showed similar structure and migration properties
with control DNA. Freezing and thawing of DNA may introduce breaks in DNA but surprisingly DNA of
germ cells are resistant to damage induced by freezing and thawing. Topoisomerases are the
enzymes that change the linking number of DNA and relax it which is necessary for DNA replication.
Nowadays topoisomerase inhibitors are widely used to treat cancers and previous reports that
packing of DNA in sperm head requires topoisomerase absence of which leads to impairment in DNA
condensation. Freeze-thaw may be responsible for damage of DNA in somatic cells but germ cells are
highly resistant to damage induced by freezing and thawing.