Fig. 3.

Juvenile Lytechinus variegatus of wild-type (A,B) and gene knock out of polyketide synthase (PKS1; C,D). Regardless of the final colormorph phenotype in the adult, juvenile spines all initially have 1–2 purple pigment bands along the nascent skeleton (white arrows). Wildtype animals also have pigmented immune cells (red spherule cells) densely packed throughout the body (asterisk). Animals whose PKS1 genes have been inactivated by Cas9/sgRNA do not have detectable pigment in either of these cells (C,D). The slight green regions in the bodies of A and C is algae in the digestive system. The juveniles at this stage are less than 2 millimeters in diameter.