Teodoro, the first genetically modified lamb in Spain, is born

On Sunday, July 14, the first genetically modified Spanish lamb was born on an experimental farm in Madrid, 1,700 meters from the Prime Minister’s office. It is called Teodoro, in honor of Teodoro Álvarez, a sheep herder from the Segovian town of Aldea Real who died this year, and grandfather of one of the leaders of the research, the veterinarian Pablo Bermejo Alvarez (Madrid, 41 years old). Scientists have modified the DNA of the lamb to eliminate a protein potentially involved in the recognition of the sperm by the egg. The authors believe that it may be key in many cases of infertility, both in women and in farm animals.

Bermejo says that they went in search of eggs to a small slaughterhouse in the town of Mondéjar, in the Alcarria region (Guadalajara). There, breeding sheep are slaughtered using the halal rite, with a cut in the throat facing Mecca, to sell the meat to the Muslim market. The researchers bought semen from a male from Churra breed in a company in Zamora and obtained Teodoro’s embryo, genetically modified using the CRISPR technique, discovered in 2012 by French biochemist Emmanuelle Charpentier and American chemist Jennifer Doudna, winners of the Nobel Prize in Chemistry in 2020.

The famous sheep Dolly was born on 5 July 1996 at the Roslin Institute in Edinburgh. Her creators, led by British embryologist Ian Wilmut, used an egg removed from a Scottish blackface sheep and the nucleus of an adult cell taken from the udder of another Finn Dorset sheep, whose DNA would be cloned into Dolly. In 1997 Polly and Molly were born, two sheep cloned from an adult cell, like Dolly, but, for the first time, with a gene added to produce a therapeutic protein in their blood.

The lamb Teodoro is already running around the experimental farm, which belongs to the National Institute of Agricultural and Food Research and Technology (INIA-CSIC). The veterinarian Priscila Ramos Ibeas (Burgos, 37 years old) has co-directed the work, which is kept secret so that other scientific teams do not get ahead of it. The authors are currently hiding which gene they have silenced.

In Spain, genetic modification of farm animal embryos is common in the laboratory, especially after the emergence of the revolutionary CRISPR genetic editing technique —simple and cheap molecular scissors—, but they are not usually implanted in a mother’s uterus to produce a birth. Bermejo recalls that his team collaborated in genetic modification of pigs in 2021, led by the veterinarian’s laboratory Joaquin Gadea at the University of Murcia. Four years earlier, Bermejo’s group generated the first genetically edited farm animals in Spain: some rabbits without the ZP4 proteinone of the four proteins that form the shell surrounding the embryo of mammals before implantation in the uterus. Researchers have shown that this protein is essential and that its removal causes infertility.

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