11.   The knockout mouse is born as if it had been exposed to cocaine.

12.   The knockout mice have high levels of a cellular protein called Fos B, which means that the gene that makes this protein is highly active.

13.   The scientists also ruled out the possibility that the knockout mice were more frightened and therefore more likely to fight.

14.   Then along came the knockout mouse.

15.   They genetically manipulated laboratory mice to delete the gene responsible for nitric oxide synthase, creating a colony of so-called knockout mice.

16.   Two years ago, Caron developed a knockout mouse that was missing the dopamine transporter.

17.   He said the knockout mouse had a slightly higher temperature than the normal mouse, possibly as a result of high fat metabolism.

18.   In the knockout mouse, said Wakil, very little fat was put into storage.

19.   Wakil said the knockout mice were permitted to eat as much food as they wanted, for as long as they wanted.