Xenbase Image ID: 75960

Figure 2. Overexpression of ADAM 13 alters neural crest-cell positioning in vivo. Embryos were injected into the animal pole of one blastomere at the two-cell stage with (b,d,j,k) 1 ng wild-type ADAM 13, (c,g,h,l,m) the E/A point mutant, or (i) the E/AδCyto transcripts. Injected embryos were cultured to (a) early-neurula stage 13 or (d) tailbud stages and processed for (a) Xslug mRNA expression (blue), (j) Xtwist, and the Myc-tag epitope (light brown). The green dot indicates the injected side of each embryo; red and blue arrowheads indicate the cranial and trunk crests, respectively. Dorsal views of (a) noninjected control embryos, (b) wild-type embryos, or (c) E/A mutants at stage 13 show no difference in the Xslug expression pattern. (d) Dorsal views of wild-type transcript-injected stage 25 (left) and 22 (right) embryos. (e) A higher-magnification view of the stage 22 embryo in (d) shows that the three cranial-crest segments visible on the control side (mandibular, m; hyoid, h; and branchial, b) appear as a single mass on the injected side (red arrowhead). (d,e) Islands of ectopic Xslug- positive trunk crest cells (blue arrowheads) are also noted in the flank on the injected side. (f) A horizontal section of a stage 24/25 embryo confirms the location of the cranial crest expressing Xslug on the injected side. Xslug expression in the head is weak at this stage, as seen in the noninjected control side (e.g., stage 25 embryo on the left in [d]). (g) Dorsal views of tailbud embryos (stage 24, left; stage 22, right) expressing the E/A point mutant. The pattern and position of the trunk crest is normal, although subtle differences in the cranial crest are observed; (h) the extent of migration of cranial crest segments on the injected side is decreased relative to that of the control side (red arrows). (i) Stronger defects are observed in embryos overexpressing the E/AδCyto protein. (j) Lateral views of tailbud stage embryos injected with wild-type ADAM 13 (j,k) or the E/A mutant (l,m). Injected embryos were stained with the cranial neural crest-cell marker Xtwist. As seen with Xslug, the cranial-crest segments of the embryo injected with wild-type ADAM 13 are not as clearly defined as those in the contra-lateral noninjected side (compare [j] and [k]). Interestingly, overexpression of the E/A ADAM 13 (compare [l] and [m]) has dramatically reduced the migration of cells from the hyoid and branchial crest segments (red arrowhead) Image published in: Alfandari D et al. (2001) Copyright © 2001. Image reproduced with permission of the Publisher, Elsevier B. V. Gene Synonyms Species Stage(s) Tissue snai2.L slug, snai2-a, snai2-b, Snail2, xSlu, xslug, XSnail2 X. laevis Throughout NF stage 13 neural crest cranial neural crest trunk neural crest twist1.S twist, twist1-a, twist1-b, X-twi, Xtwi, Xtwist X. laevis Throughout NF stage 13 neural crest cranial neural crest trunk neural crest snai2.L slug, snai2-a, snai2-b, Snail2, xSlu, xslug, XSnail2 X. laevis Sometime during NF stage 22 to NF stage 25 neural crest cranial neural crest anterior branchial crest posterior branchial crest hyoid crest mandibular crest trunk neural crest Image source: Published Larger Image Printer Friendly View

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