Scientists create embryos, hope to save the almost extinct white rhino :: Kenya

Months after the death of Sudan's last white male northern rhino, scientists said Wednesday they have been growing embryos containing DNA of its kind, hoping to save the subspecies of the species. extinction.

With only two white rhinos (NWR) known to be alive today – both female infertile – the team hopes that their revolutionary technique will lead to the recovery of a viable NWR breeding population.

"Our goal is to have in three years the first calf of NWR," said Thomas Hildebrandt, head of reproductive management at the Leibniz Institute for Zoological and Wildlife Research in Berlin.

"Given 16 months of pregnancy, we have a little over a year to successfully implant."

The team's work, using a newly patented two-meter (6.6-foot) eggs extraction device, resulted in the first-ever rhinoceros embryo produced by test.

Now frozen, they "have a very good chance of establishing a pregnancy once implanted in a surrogate mother," says Hildebrandt.

Hybrid embryos were created with frozen sperm from NWR dead males and eggs from the southern white rhinoceros. (SWR) females, of whom there are still thousands on Earth.

Eggs were harvested from rhinos in European zoos.

The team is now hoping to use the technique to collect eggs from the last two northern white rhinos – Najin and Fatu, Sudan's daughter and granddaughter. They live in a national park of Kenya.

Risk and Reward

By fertilizing these with northern white rhinoceros sperm and implanting the resulting embryos into females carrying southern white rhinos, the team plans to create a new NWR population nascent.

"Our results indicate that ART (badisted reproductive techniques) could be a viable strategy to save the northern white rhinoceros genes, almost gone," the team wrote in Nature Communications .

The researchers asked permission to harvest eggs from Najin and Fatu in Kenya, hopefully before the end of the year.

But the procedure is not without risk: "we must do a complete anesthesia, the animal is down for two hours, and it's a pretty risky situation" for the last two conceded Hildebrandt.

"We are very afraid that something unexpected will happen, it would be a nightmare."

Meanwhile, the team will train, implanting some of their hybrid embryos into SWR substitutes "to test the system".

Any hybrid born accordingly can play a crucial future role as substitutes, sharing more genes with northern rhinos than purely southern substitutes.

There is however a major obstacle to the NWR repopulation envisaged by the team.

With only two remaining NWR females and all the available sperm of only four dead males, single TAR would likely lead to a population without the genetic diversity required for a successful species.

Can this work?

To this end, researchers hope to use stem cell technology to make eggs and sperm from the frozen skin cells of 12 dead white rhinos, unrelated to each other.

"This would greatly expand the founding diversity of the future NWR population," said the team in a statement.

There is a time pressure, they said, with only two animals still present to socialize babies in the mysterious way of Northern white rhinos.

"It's a motivating aspect to succeed as quickly as possible so that the veal we produce can grow with Najin and Fatu," Hildebrandt said.

Terri Roth and William Swanson of the Zoo and Cincinnati Botanical Garden, in a commentary on the study, said that antiretroviral therapy alone can not save a species from extinction.

"Impressive results in a petri dish do not easily translate into a healthy flock of offspring," writes the duo, not involved in the research.

"To reach the latter, one must navigate a non-trampled path and full of obstacles, and it remains unlikely that a viable population of Northern White Rhinos will be restored."

For researchers, however, a combination of antiretroviral therapy and stem cell techniques could "provide a blueprint on how to save highly endangered species that have already declined to numbers that make conventional conservation efforts impossible" .