Facility Manager - Dr. Paul Thomas FRMS FPhysiol
In February 2003, I was appointed to run the newly-formed Henry Wellcome Laboratory for Cell Imaging here at the University of East Anglia (UEA). Before this appointment, my research career had focused on calcium signalling with a major emphasis on membrane biology and, in particular, exocytosis. During my career I have worked on a variety of cellular systems which gives me a broad and diverse scientific background. I have also gained enormous experience in a variety of techniques from biochemical to electrophysiological and microscopical.
My first job after graduation was as a lipid biochemist working with Dr. David Allan at University College Hospital Medical School on the role of lipids in the shape changes that occur in erythrocytes during cell ageing and sickle-cell anaemia (refs. 1-4). I then journeyed across the Atlantic to California where I worked with Dr. Stan Meizel (UC Davis) on events that prepare spermatozoa for fusion with oocytes. It was here that I began my Ph.D., and where I used my knowledge of lipid biochemistry to investigate the involvement of phosphoinositide metabolism in calcium mobilization brought about by a steroid hormone (progesterone) acting at the cell surface – one of the first studies to show, unequivocally, that steroids could have rapid, non-genomic effects on cell function (refs. 5 & 6; and see commentary in 7). It was also in this work that I was introduced to fluorescence technology and the use of fura-2; albeit, in populations of cells in a cuvette.
After obtaining my Ph.D. I took up a postdoctoral position in the laboratory of Dr. Wolf Almers at the University of Washington in Seattle. Here I completely switched gears from biochemical and cell biological approaches to using the whole-cell patch-clamp technique to study single cells. As well as learning electrophysiology, I also began my first microscopical studies by combining the patch-clamp methodology with microfluorimetry of fura-2 fluorescence (but still no imaging, that would come later). By using capacitance measurements of exocytotic activity in response to flash photolytic release of caged calcium, I was able to reveal, for the first time, the calcium affinity of the receptor that controls secretory activity in endocrine cells (refs. 8 & 9), and to measure the rapid recapture of secretory vesicle membrane in the same cells (ref. 10).
After adding these new methodological strings to my bow, I returned to Davis to work with Drs. Denis Waring and Judy Turgeon to investigate the relationship between intracellular calcium and secretory activity in pituitary gonadotrophs. In this work I used a variation of the whole-cell recording method – the perforated patch technique. In so doing, I was able to monitor secretory activity in response to cytosolic calcium oscillations under conditions that maintain an intact intracellular signalling cascade (ref. 11).
Following 14 years on the west coast, I returned to England to take up a fellowship in the Department of Pharmacology at the University of Cambridge. It was here that I finally became an "imager". In Cambridge, in collaboration with Dr. Mike Edwardson, I obtained a grant from the BBSRC that enabled me to establish an experimental apparatus that combined electrophysiology with digital imaging for the investigation of calcium signalling and membrane trafficking in single, exocrine cells. Using this technology, my post-docs and I were able to use simple brightfield recordings combined with time-differential analysis to investigate the control of zymogen granule exocytosis in pancreatic acinar cells in response to acetylcholine (ref. 12). In this work we revealed an intriguing dose-dependent cross-talk between signalling pathways downstream of muscarinic receptors (refs. 13 & 14).
On coming to UEA, I have been instrumental in establishing the Henry Wellcome laboratory as a user-friendly facility catering to scientists with wide-ranging imaging needs; from imaging newly-developed fluorescent probes (ref. 15), to single cells (refs. 16 & 17), to whole organisms (ref. 18) both live and fixed. As a physiologist, I understand the need to develop novel technologies and procedures to address new research questions. I am also aware that these technologies must be accessible to the user, flexible enough to answer all the questions posed, and fast enough to ensure that valuable research time and funding are not wasted.
1. D. Allan, P. Thomas & R. H. Michell (1978). Rapid transbilayer diffusion of 1,2-diacylglycerol and its relevance to control of membrane curvature. Nature, 276, pp. 289–290. DOI: 10.1038/276289a0
2. D. Allan and P. Thomas (1981). Ca2+-induced biochemical changes in human erythrocytes and their relation to microvesiculation. Biochem. J., 198, pp. 433–440. DOI: Not available (pdf)
3. D. Allan, A. R. Limbrick, P. Thomas & M. P. Westerman (1982). The release of spectrin-free spicules on reoxygenation of sickled erythrocytes. Nature, 295, pp. 612–613. DOI: 10.1038/295612a0
4. P. Thomas, A. R. Limbrick & D. Allan (1983). Limited breakdown of cytoskeletal proteins by an endogenous protease controls Ca2+-induced membrane fusion events in chicken erythrocytes. Biochim. Biophys. Acta, 730, pp. 351–358. DOI: 10.1016/0005-2736(83)90352-8
5. P. Thomas and S. Meizel (1988). An influx of extracellular calcium is required for initiation of the human sperm acrosome reaction induced by human follicular fluid. Gamete Res., 20, pp. 397–411. DOI: 10.1002/mrd.1120200402
6. P. Thomas and S. Meizel (1989). Phosphatidylinositol 4,5-bisphosphate hydrolysis in human sperm stimulated with follicular fluid or progesterone is dependent upon Ca2+ influx. Biochem. J., 264, pp. 539–546. DOI: Not available (pdf)
7. N. Touchette (1990). Man bites dogma: A new role for steroid hormones. J. NIH Res., 2, pp. 71-74. DOI: Not available (pdf)
8. P. Thomas, J. G. Wong & W. Almers (1993). Millisecond studies of secretion in single rat pituitary cells stimulated by flash photolysis of caged Ca2+. EMBO J., 12, pp. 303–306. DOI: Not available (pdf)
9. P. Thomas, J. G. Wong, A. K. Lee & W. Almers (1993). A low-affinity Ca2+ receptor controls the final steps in peptide secretion from pituitary melanotrophs. Neuron, 11, pp. 93–104. DOI: 10.1016/0896-6273(93)90274-U
10. P. Thomas, A. K. Lee, J. G. Wong & W. Almers (1994). A triggered mechanism retrieves membrane in seconds after Ca2+-stimulated exocytosis in single pituitary cells. J. Cell Biol., 124, pp. 667–675. DOI: 10.1083/jcb.124.5.667
11. P. Thomas & D. W. Waring (1997). Modulation of stimulus-secretion coupling in single rat gonadotrophs. J. Physiol. (Lond.), 504, pp. 705-714. DOI: 10.1111/j.1469-7793.1997.705bd.x
12. M. Campos-Toimil, J. M. Edwardson & P. Thomas (2000) Real-time studies of zymogen granule exocytosis in intact rat pancreatic acinar cells. J. Physiol. (Lond.), 528, pp. 317-326. DOI: 10.1111/j.1469-7793.2000.00317.x
13. M. Campos-Toimil, T. Bagrij, J. M. Edwardson & P. Thomas (2002) Two modes of secretion in pancreatic acinar cells: involvement of phosphatidylinositol 3-kinase and regulation by capacitative Ca2+ entry. Curr. Biol., 12, pp. 211-215. DOI: 10.1016/S0960-9822(01)00661-3
14. P. Thomas, T. Bagrij, M. Campos-Toimil & J. M. Edwardson (2006) Mitochondria play a critical role in shaping the exocytotic response of rat pancreatic acinar cells. Cell Calcium, 39, pp. 57-63. DOI: 10.1016/j.ceca.2005.09.007
15. M. J. Marín, F. Galindo, P. Thomas & D. A. Russell (2012) Localized intracellular pH measurement using a ratiometric, photoinduced electron-transfer-based nanosensor. Angew. Chem. Int. Ed., 51, pp. 9657-9661. DOI: 10.1002/anie.201203866
16. R. Roberts, W. T. Al-Jamal, M. Whelband, P. Thomas, M. Jefferson, J. van den Bossche, P. P. Powell, K. Kostarelos & T. Wileman (2013) Autophagy provides a barrier against non-viral gene delivery. Autophagy, 9, pp. 667-682. DOI: 10.4161/auto.23877
17. D. A. Goldspink, J. R. Gadsby, G. Bellett, J. Keynton, B. J. Tyrrell, E. K. Lund, P. P. Powell, P. Thomas & M. M. Mogensen (2013) The microtubule end-binding protein EB2 is a central regulator of microtubule reorganisation in apico-basal epithelial differentiation. J. Cell Sci., 126, pp. 4000-4014. DOI: 10.1242/jcs.129759
18. G. C. Kearn, I. D. Whittington & P. Thomas (2012) A new species of Asthenocotyle Robinson, 1961 (Monogenea: Microbothriidae), a skin parasite of the great lanternshark, Etmopterus princeps Collett from the Azores, with a redescription of A. kaikourensis Robinson, 1961 and observations on A. taranakiensis Beverley-Burton, Klassen & Lester, 1987. Syst. Parasitol., 83, pp. 145-158. DOI: 10.1007/sl1230-012-9378-3