Sea Lampreys
Sea lampreys are an ancient jawless fish with over a half-billion years in lineage. Their approach to gene-driven development is extremely conservative.
The genic instructions that guide embryotic development produce pluripotent stem cells, which can differentiate into any cell type. To prevent untoward problems, these potent genes are laid aside in lampreys after early development; sealed away so as not to risk their being misexpressed.
Lampreys experience rampant programmed genome rearrangement and losses during early development. The genes are restricted to the germline compartment suggesting a deeper biological strategy to regulate the genome for highly precise, normal functioning. The strategy removes the possibility that the genes will be expressed in deleterious ways. Humans, on the other hand, must contain these genes through other epigenetic mechanisms that are not foolproof. ~ American biologist Chris Amemiya
