Relocations of cell convergence sites and formation of pharyngula-like shapes in mechanically relaxed <Emphasis Type="Italic">Xenopus</Emphasis> embryos |
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Authors: | Evgenia S Kornikova Elena G Korvin-Pavlovskaya Lev V Beloussov |
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Institution: | (1) Department of Embryology, Faculty of Biology, Moscow State University, Moscow, 119899, Russia |
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Abstract: | Influence of the relaxation of mechanical tensions upon collective cell movements, shape formation, and expression patterns
of tissue-specific genes has been studied in Xenopus laevis embryos. We show that the local relaxation of tensile stresses within the suprablastoporal area (SBA) performed at the early-midgastrula
stage leads to a complete arrest of normal convergent cell intercalation towards the dorsal midline. As a result, SBA either
remains nondeformed or protrudes a strip of cells migrating ventralwards along one of the lateral lips of the opened blastopore.
Already, few minutes later, the tissues in the ventral lip vicinity undergo abnormal transversal contraction/longitudinal
extension resulting in the abnormal cell convergence toward ventral (rather than dorsal) embryo midline. Within a day, the
dorsally relaxed embryos acquire pharyngula-like shapes and often possess tail-like protrusions. Their antero-posterior and
dorso-ventral polarity, as well as expression patterns of pan-neural (Sox3), muscular cardiac actin, and forebrain (Otx2)
genes substantially deviate from the normal ones. We suggest that normal gastrulation is permanently controlled by mechanical
stresses within the blastopore circumference. The role of tissue tensions in regulating collective cell movements and creating
pharyngula-like shapes are discussed. |
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Keywords: | Xenopus laevis Mechanical stresses Gastrulation Convergent cell intercalation Pharyngula |
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