Cephalochordates ("amphioxus" or "lancelet") are an ideal model for studying developmental and regenerative processes (Bertrand and Escriva 2011; Somorjai 2017). Although amphioxus is an invertebrate, it is a chordate; as such, it shares many morphological features with vertebrates, including a notochord, a dorsal nerve cord, and segmented musculature. However, it is much simpler anatomically and genomically, with many fewer cell types and a much reduced gene complement. Unlike most vertebrates however, including humans, amphioxus regenerates extremely well (Somorjai et al 2012). We still know little about the mechanisms governing regenerative ability in amphioxus, but understanding how an animal like amphioxus regenerates major structures like the tail could give important clues to improving regeneration in poorly regenerating species (like us!). Our research therefore has clear implications for biomedicine and stem cell biology, but also gives us important insight into the evolution of regeneration mechanisms due to cephalochordates´ key phylogenetic position at the invertebrate-to-vertebrate transition.
The Somorjai lab is working to understand the molecular and cellular basis of regeneration in adult amphioxus. We have identified candidate genes with putative roles during regeneration in an adult amphioxus regenerate transcriptome. Among these, homeobox genes, such as the Hox or Paired families, are important for patterning and cell fate decisions during development (see for example Barton-Owen et al 2018), roles that may be recapitulated during regeneration. We are also interested in how the nervous system, signaling pathways, stem cells, proliferation and apoptosis (cell death) contribute to properly growing back functional structures. We benefit from active collaborations both internationally and within the University of St Andrews, for instance in the use of cutting-edge technologies to image development and regeneration (eg School of Physics; see Yang et al 2019).
In this project, you will use bioinformatics, molecular biology including gene cloning and in situ hybridisation, quantitative PCR, immunohistochemistry, lineage tracing, confocal microscopy and histology to study amphioxus regenerate patterning. There may also be the opportunity to apply transcriptomics or other "omics" approaches. Specific research topics will depend on the candidate´s interests, but objectives could include:
1. Characterisation of candidate gene or protein expression in unamputated and regenerating animals.
2. Characterisation of lineages using labelling techniques (eg nerve cord, muscle, notochord)
3. Use of functional techniques to disrupt regeneration and assess changes in cell fate, proliferation or cell death
The ideal candidate will be independent and self-motivated, and have experience with at least some of the techniques required for the project; however, training will be provided. Possession of a Masters degree in a relevant biological field is desirable. Alongside laboratory skills, the PhD candidate will gain experience in animal husbandry, article writing for publication, presentation skills, statistics and quantification, and will be able take advantage of a number of postgraduate courses offered by the University of St Andrews through CAPOD.
Please send informal enquiries to Dr. Ildiko Somorjai: [email protected]
Lab webpages: http://www.st-andrews.ac.uk/profile/imls
Yang, Z, Cole, KLH, Qiu, Y, Somorjai, IML, Wijesinghe, P, Nylk, J, Cochran, S, Spalding, GC, Lyons, DA & Dholakia, K (2019) Light sheet microscopy with acoustic sample confinement' Nature Communications 10: 669.
Barton-Owen T, Ferrier DEK, Somorjai IML (2018) Pax3/7 duplicated and diverged independently in amphioxus, the basal chordate lineage. Scientific Reports 8(1):9414.
Somorjai IML (2017) Amphioxus regeneration: evolutionary and biomedical implications. Int J Dev Biol. 61(10-11-12):689-696.
Somorjai IM, Somorjai RL, Garcia-Fernàndez J, Escrivà H. (2012) Vertebrate-like regeneration in the invertebrate chordate amphioxus. Proc Natl Acad Sci U S A. 109(2):517-22.
Bertrand S, Escriva H (2011) Evolutionary crossroads in developmental biology: amphioxus. Development. 138(22):4819-30.