Friday, 22 February, 2019

Can test-tube rhinos save dying species?

The pre-implantation embryos are known as blastocysts The pre-implantation embryos are known as blastocysts
Theresa Hayes | 07 July, 2018, 06:46

They used sperm from the last northern white rhino males before they died.

A team of global scientists has performed the first ever in vitro fertilisation for a rhinoceros and researchers say frozen sperm could be used to create new embryos.

The amount of semen preserved from northern white rhinos in frozen stocks is from only three bulls, meaning there is not a lot of genetic diversity.

The embryos were produced with the help of eggs from sub-species that were closely related, but Scientists assert that the approach could save the northern white rhino.

Once fertilisation occurred, forming a zygote, the team stimulated the growth of the zygote for between seven and twelve days, to the developmental stage called a blastocyst - at which point it is ready to be implanted in the uterus. The Washington Post's Ben Guarino reports that to produce the hybrid embryos, scientists retrieved the southern females' eggs with a 60-inch-long instrument that enables the collection of ovarian tissue.

"Our goal is that we have, in three years, the first northern white rhino calf born", said Thomas Hildebrandt, of the Leibniz Institute for Zoo and Wildlife Research in Berlin.

These embryos could become healthy young white rhino calves once implanted into females.

Getting this far was no easy feat, however, as the team explained that it had to create an entirely new extraction device just to obtain an oocyte (egg) from the female rhino.

That means a southern white rhino would have to serve as a surrogate, and no one knows whether a southern white rhino can carry a northern white rhino baby.

Can the research lead to a self-sustaining wild rhino population? An global team of researchers has successfully created NWR hybrid embryos in the lab, according to a study published Wednesday in the journal Nature Communications. While this only worked for southern white rhino embryos and not the hybrids, it did demonstrate the method could be successful.

These researchers are certain that this process could save the northern whiterhino.

Hildebrandt and his colleagues have taken the first step to put these plans into action, creating the first viable embryos of the extinct Northern white rhinos, the last of which individuals live their lives in zoos in Asia, Africa and other continents of the world. An worldwide team of researchers successfully managed to adapt reproduction techniques used in horses to the special circumstances of rhino species, opening up the potential to bring back NWR from the brink of extinction.

However, because of the complexity around creating pure northern white rhino embryos, Galli estimates that it will take 10 years to accomplish.

"It is important that we learn from the plight of the northern white rhino and we make sure what happened to it does not happen to other endangered species". Dr. Roth says that poaching is a significant threat to the rhino species. They also showed that the genetic differences between the northern and southern subspecies may be the result of evolutionary adaptations to different habitats. The team has tissue samples from northern white rhinos. The introduced rhino population would be expected to evolve over generations to adapt to their new environment and fill the ecological role left vacant by the northern white rhino. Without any way to procreate naturally, it may look like the subspecies is nearing extinction.