In an effort to save the Yellow Spotted Monitor species, researchers from the Macquire University revealed a new sperm freezing and revival technique that shows considerable promise. Simon Clulow and his colleagues wrote in an article published in Conservation Physiology that this technique involves a surprising ingredient.
The team took sperm from a number of the giant lizard or "goanna" species that have suffered severe population declines in recent years as cane toads moved into their habitat, and for a lizard, a toad is a tasty and lethal threat.
Their population dropped by 97% by then, with huge knock-on effects throughout its ecosystem. The Yellow Spotted Monitor needs urgent help.
The Freezing Technique Plus Caffeine
According to Phys.org, the researchers are set to find out which freezing technique works best, and which was the best protocol in getting the frozen sperm moving again after thawing it out.
They discovered that there is one common cryoprotectant, dimethyl sulfoxide, or DMSO for short that can do the job very well.
"We were excited to find that we could use a relatively simple cryoprotectant to prevent the sperm from being ripped apart by ice crystals during the freezing process," Clulow said.
"It was a promising start. But as with a small number of previous attempts to freeze reptile sperm, we weren't able to retrieve large numbers of mobile, swimming sperm post-thaw," he added.
The researchers decided they needed to try a new technique not used to lizards before if they wanted to make a breakthrough in saving many of the motile lizard sperm. This method had been used in sperm samples of mammals and birds, but this will be the first time that it will be used on lizards or to any reptile.
According to Lachlan Campbell, Ph.D. Student and first author of the study, the team added caffeine to stimulate the sperm when they thawed the sperm out. To the researchers' delight, there is a huge increase in the number of moving sperm after freezing and thawing.
"It turns out, frozen lizard sperm need their morning coffee to get started just like us!" Campbell said.
#Lizards need their coffee, too: Could caffeine help bring threatened species back from the brink? @macquarie_uni https://t.co/1qm2FeWUQm — Phys.org (@physorg_com) June 23, 2020
A Promising Path for Reptile Conservation
The team did a series of experiments to perfect the technique and was able to retrieve nearly half the sperm cells they froze. So far, this is the greatest recovery of motile sperm reported for any reptile species.
This technique offers a new promising path for reptile conservation across the globe, specifically for Australian lizards.
Moreover, it provides new opportunities to build up the ambitious conservation insurance that Clulow and his colleague Dr. Sean Dood at the University of South Florida established, known as the Kimberley Ark gene bank.
The project was established to restore genetic diversity after the sadly inevitable wildlife devastation because of the westward march of the cane toads all over northern Australia.
Both the researchers agree that the technique in retrieving the sperm is a large step in the right direction to protecting the genetic diversity of the unique reptile predators in northern Australia.
