Somite Rotation in amphioxus and its implications on the evolutionary emergence of the vertebrate backbone
Supervisor: Dr Èlia Benito-Gutiérrez
During vertebrate development the formation of somites is a critical step in forming the vertebrae, the muscles and the dermis. In Xenopus and Zebrafish the development of these vertebrate somite derivatives relies on a 90-degree rotation of the somites to become aligned parallel to the notochord. We have recently discovered that somites in amphioxus rotate as described in Xenopus and Zebrafish. This process seems to be somehow dependent on Notch signaling. The project will consist in characterizing this process in the invertebrate amphioxus from a morphogenetic point of view. It will involve comparative analyses of wild type and mutant embryos. The project will benefit from a collaboration with the Cambridge Advanced Imaging Centre (CAIC) to use light sheet microscopy and monitor in 3D the rotation of the somites in wild type and mutant amphioxus embryos.
What the student will be doing:
The project will start by characterising the phenotype of mutant amphioxus embryos and comparing their morphology to that of wild type embryos. This will be done by morphometric analyses and staining of the embryos either with general or tissue specific markers. Specific genes will be used to probe the regional identity of the affected somites. Once the phenotype is fully characterised the molecular basis for this phenotype will be investigated via RNA-Seq Profiling of mutant and wild type embryos. This will allow identifying genes with major roles in somite rotation. These genes will be then be cloned and mapped by in situ hybridisation in mutant and wild type embryos.
1.Hollway, G. E., Bryson-Richardson, R. J., Berger, S., Cole, N. J., Hall, T. E., & Currie, P. D. (2007). Whole-Somite Rotation Generates Muscle Progenitor Cell Compartments in the Developing Zebrafish Embryo. Developmental Cell, 12(2), 207–219.
2.Afonin, B., Ho, M., Gustin, J. K., Meloty-Kapella, C., & Domingo, C. R. (2006). Cell behaviors associated with somite segmentation and rotation in Xenopus laevis. Developmental Dynamics, 235(12), 3268–3279.
3.Beaster-Jones, L., Kaltenbach, S. L., Koop, D., Yuan, S., Chastain, R., & Holland, L. Z. (2008). Expression of somite segmentation genes in amphioxus: a clock without a wavefront? Development Genes and Evolution, 218(11-12), 599–611.