BEIJING, Nov. 11 — British scientists Tuesday begin to study how human DNA could be used in animal experiments, and to define what the boundaries of such controversial science could be.

Robin Lovell-Badge, a stem cell expert at Britain’s National Institute for Medical Research, and a member of the group conducting the study, said there are two main types of experiments: altering an animal’s genes by adding human DNA or replacing a specific animal sequence with its human counterpart.

The researchers said they are now trying to determine where the line should be drawn on experiments that use human material in animals. At the moment, the regulation on how much human DNA can be put into an animal is vague.

Scientists want to make sure the public is aware of what is happening in laboratories before proceeding further. They said they recognized people might be nervous about experiments where animals were given human features or brain cells.

“We are trying to work out what is reasonable,” said Martin Bobrow, chairman of the group conducting the study.

Controversy erupted in Britain after scientists announced plans to create human embryos using empty cow and rabbit eggs two years ago. 

On Xinhua Web site: http://news.xinhuanet.com/english/2009-11/11/content_12430412.htm