gata5 expression phenotypes obtained from a cross of fish doubly heterozygotic for squint (sqt cz35) and cyclops (cycm294). Expression was assayed at 30-40% epiboly (A-C, left embryos oblique animal pole view, right embryos lateral view) and shield stage (D-F, animal-lateral view). A and D show the normal expression pattern seen in most embryos. (A) At 30-40% epiboly, expression is in the margin of the blastoderm (open arrowhead) and the underlying YSL (black arrowhead). At shield stage (D) gata5 is expressed in the newly involuted hypoblast. One abnormal phenotype (B and E) was the same as that found in embryos from crosses of sqt single heterozygotes. At 30-40% epiboly (B), expression of gata5 in the blastoderm margin was generally weaker (black arrows) and in some embryos expression was absent from part of the blastoderm margin (white arrowheads). At shield stage (E), expression was absent from typically one quarter of the hypoblast (white arrowheads), and reduced in the remainder. In the second abnormal phenotype, representing embryos homozygous for both sqtcz35 and cycm294, gata5 was completely absent from blastomeres at both stages (C and F). Some remaining expression could be seen in the YSL (C, black arrowhead).
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