Figure 5.

Analysis of mesodermal markers in injected embryos. Embryos injected with Jak^Wt RNA possess a band of axial mesoderm (AM), which expresses ntl and axial, extending anteriorly from the vegetal pole (VP). Embryos injected with mutant forms of Jak1 kinase possess broader expression domains for these genes, which are twice as wide and extend half as far anteriorly. Reduced epibolic movements are evident in embryos injected with mutant forms of Jak kinase by the gap between the ntl expressing cells of the blastoderm margin (BM) and the vegetal pole. In a rescue experiment, Jak^Wt and Jak^ΔKin RNAs were injected together in a 3:1 molar ratio. This yields partial rescue, with narrower expression domains that extend more anteriorly. Embryos injected with Jak^Wt RNA show goosecoid staining marking the anterior shield (AS). Embryos injected with mutant forms of Jak1 kinase show reduced goosecoid expression.