Preserving genetic material is an important way to ensure the long-term viability of Canada’s agriculture sector, because it ensures scientists will have diverse genetic material for future breeding, according to a release from Agriculture and AgriFood Canada (AAFC).
Vitrification has become a common practice in preserving animal genetic material, but it does not work well for bovine eggs, the release said. Using synchrotron technology, AAFC research gives us a new look at what happens inside these egg cells and makes a surprising discovery.
While seed diversity and conservation initiatives are well established in Canada and around the world, the preservation of farm animal genetic material remains a challenge, mainly because of the associated costs and technical difficulties of storing animal and poultry germplasm (sperm, eggs, embryos and gonads).
Mammalian genetic material can be stored at ultra-low temperatures in liquid nitrogen via a slow freezing process called cryo-preservation. However, livestock oocytes – also known as female eggs – are difficult to preserve.
Dr. Muhammad Anzar, AAFC cryobiologist with the Canadian Animal Genetic Resources Program (CAGR) in Saskatoon, has researched how to improve the preservation of livestock breeds, specifically bovine eggs.
Vitrification, a simple and cost-effective procedure that takes preservation to the next level, is the ultra-rapid cooling of tissue where the tissue is not technically frozen (no ice crystals form) but rather maintained in a glass-like or “vitreous” state at ultra-low temperature. In vitrification, most of the water in a cell is replaced with cryoprotectants (antifreeze compounds) and cooled ultra-rapidly. The cells cool at a rate of about 4,000 to 5,000 degrees Celcius a minute or more, so ice has almost no time to form, with the cell instead reaching a glass phase.
Dr. Anzar undertook a new research technique with the Canadian Light Source (CLS) using the synchrotron x-ray beamline to get a better look at what happens to the bovine egg when it undergoes the vitrification process. He is the only scientist attempting to confirm the ice or glass phase in cells or tissues of bovine eggs, which makes this research very unique.
Through a partnership with Dr. Pawel Grochulski from the Canadian Macromolecular Crystallography Facility (CMCF) at CLS in Saskatoon, it has been confirmed that inside the bovine egg, ice crystals still continue to form. Something about the egg is resistant to preservation.
“We were able to use the synchrotron x-ray beamline at the CMCF and, for the first time, get a rare look at what is act – it’s not what was expected,” Grochulski said.
Dr. Muhammad Anzar, AAFC Cryobiologist, Canadian Animal Genetic Resources Program, Saskatoon said that the reason for the resistance is yet to be uncovered, but with this new ability to observe crystal formation in the vitrification process, he will continue his exploration. Future research could use fluorescent biomarkers to determine the cells’ health in the frozen state, or look into what is preventing the egg cells from reaching a glass-like phase.
Through a partnership with the Canadian Macromolecular Crystallography Facility (CMCF) at the Canadian Light Source, for the first time, x-ray diffraction technology was used to confirm that, contrary to the popular theory, inside the bovine egg, ice crystals still continue to form.
This study opened a gateway to study the behaviour of cells at low temperature, and that will be a new dimension for using CMCF to improve the frozen cells’ health, the release said.
