Sasaki's team made such a founder. They used a virus to insert the fluorescence gene into the DNA of 80 fertilized marmoset eggs. Surrogate mothers successfully bore five infants named Hisui, Banko, Wakaba, Kei, and Kou. Last month, Kou fathered a son that retained the gene, confirmed both by glow and genetic test.
Next, Sasaki's group plans to integrate genes for Parkinson's disease and amyotrophic lateral sclerosis (Lou Gehrig's disease) into the lab's marmosets. These are complex brain diseases that mouse models don't faithfully mimic. The researchers say they are genetically simpler to incorporate into primate DNA than, say, genes for cystic fibrosis -- but the team has their eye on modeling that disorder, too.