Our work is supported by the BBSRC (SW, CJS, PvW), NERC (PvW) and the University of Aberdeen (CJS, PvW, ID). This work was supported by EU East-NMR FP7 Project (Contract 228461) and Polish National Centre for Research and Development under research grant number 178479 (contract number PBS1/A9/ 13/2012) (for IZ). We would like to acknowledge Kevin MacKenzie of the core microscopy facility of the University of Aberdeen for helpful suggestions and Prof. Regine Kahmann for critical reading of the manuscript. On behalf of all authors, the ASPB journals deposit final published articles in PubMed Central for release 12 months after the date of publication (unless a free-access option applies). The final pdf of the article will be open access.Peer ...