PARIS, Sept 27: A French company says it has produced the world’s first cloned rats, two males and two females, according to Saturday’s issue of Science, the authoritative US scientific publication, which stresses that the rats could serve as models for the study of such illnesses at Alzheimer’s disease.

Officials of the Lyons-based company, Genoway, which had already produced in December 2001 the embryos of cloned rats, announced that they’d reached this milestone in collaboration with INRA, the French governmentally-operated research organisation that specializes in agronomy.

Genoway says that rats, contrary to other animals, have an ovum which, once it is removed, unleashes an internal clock mechanism that starts a countdown which nothing can stop. As a result, all attempts at transferring the nucleus of a somatic cell from an adult rat to replace the nucleus of the ovum are doomed to failure simply because the cytoplasm, the envelope wrapped around the ovum, cannot communicate in phase with the new nucleus, supposed to bring about its reprogramming. So, the embryos almost automatically abort the process.

To get around this obstacle, Genoway and their collaborators at INRA came up with a new invention — which has been patented — which blocks the ovum before the nucleus of the cell of the rat — that is to be replicated — is introduced.