Yr Athro Karl Swann

Chair

: swannk1@cardiff.ac.uk
: +44 292087 9009
: Adeilad Syr Martin Evans, Rhodfa'r Amgueddfa, Caerdydd, CF10 3AX

: Ar gael fel goruchwyliwr ôl-raddedig

I am interested in cell signalling and metabolism during animal fertilization and early embryo development. I use live cell imaging methods including those based on fluorescence and chemiluminescence.

Selected projects are:

1. The role and mechanism of action of PLCzeta in causing Ca²⁺ oscillation in eggs at fertilization

2. The relationship between Ca²⁺ and mitochondrial ATP production in eggs

3. Lipid droplets and lipid metabolism in eggs and early embryos using CARS microscopy

Roles

Deputy Module Leader and teaching on BI2331 Physiology
Teaching on BI2231 Cell Biology
Supervision of projects for Final Year Undergraduate and Masters students
Chair of School Research Ethics Committee

I completed my BSc Degree and the PhD in the Physiology Department at UCL under the supervision of Michael Whitaker. I worked as a postdoc in Japan with Shun-ichi Miyazaki studying Ca²⁺ oscillations at fertilization in eggs and returned to London to work with David Whittingham at St George’s Hospital Medical School. In 1994 I was appointed as a lecturer in the Department of Anatomy and Developmental Biology at UCL. Then in 2004 I was appointed as the Chair of Reproductive Cell Biology in the School of Medicine at Cardiff University. In 2016 I moved to the School of Biosciences. I hold an HFEA Research Licence to study human egg activation and I am an Editorial Board Member of the journal ‘Reproduction’. I have presented my research at many international meetings including invited talks at five Gordon Research Conferences.

In the 1990s I first described the existence of a soluble sperm protein that could trigger Ca²⁺ oscillations in mammalian eggs. I pioneered the theory that the sperm activates the egg by introducing a soluble sperm protein after gamete fusion. This mechanism of egg activation is now widely recognized as the way the sperm causes egg activation and initiates development. Work in my lab first showed that the principal mammalian sperm factor is a phospholipase C (PLC). Then in collaboration with Tony Lai at Cardiff University I helped demonstrate that the factor is a PLCzeta. I continue to work on egg activation and aspects of mitochondrial metabolism in mammalian eggs.

2021

Storey, A.et al. 2021. The role of ATP in the differential ability of Sr2+ to trigger Ca2+ oscillations in mouse and human eggs. Molecular Human Reproduction 27(1), article number: gaaa086. (10.1093/molehr/gaaa086)

2020

Swann, K. 2020. The soluble sperm factor that activates the egg: PLCzeta and beyond. Reproduction 160(1) (10.1530/REP-20-0079)

2019

Bradley, J.et al. 2019. Dynamic label-free imaging of lipid droplets and their link to fatty acid and pyruvate oxidation in mouse eggs. Journal of Cell Science 132(13), article number: jcs228999. (10.1242/jcs.228999)
Bradley, J. and Swann, K. 2019. Mitochondria and lipid metabolism in mammalian oocytes and early embryos. International Journal of Developmental Biology 63(3-4-5), pp. 93-103. (10.1387/ijdb.180355ks)
Borri, P.et al. 2019. Imaging lipids in living mammalian oocytes and early embryos by coherent Raman scattering microscopy. Presented at: SPIE BIOS, San Francisco, CA, USA, 2-7 February 2019Proceedings Volume 10890, Label-free Biomedical Imaging and Sensing (LBIS) 2019, Vol. 108900. Society of Photo-Optical Instrumentation Engineers (SPIE) pp. 3., (10.1117/12.2506248)

2009

Dumollard, R.et al. 2009. Mitochondrial function and redox state in mammalian embryos. Seminars in Cell and Developmental Biology 20(3), pp. 346-353. (10.1016/j.semcdb.2008.12.013)

2008

Ajduk, A. M.et al. 2008. Fertilization differently affects the levels of cyclin B1 and M-phase promoting factor activity in maturing and metaphase II mouse oocytes. Reproduction 136(6), pp. 741-752. (10.1530/REP-08-0271)
Yu, Y.et al. 2008. Regulation of diacylglycerol production and protein kinase C stimulation during sperm- and PLCζ-mediated mouse egg activation. Biology of the Cell 100(11), pp. 633-643. (10.1042/BC20080033)
Dumollard, R.et al. 2008. Regulation of cytosolic and mitochondrial ATP levels in mouse eggs and zygotes. Developmental Biology 316(2), pp. 431-440. (10.1016/j.ydbio.2008.02.004)
Yu, Y.et al. 2008. Preimplantation development of mouse oocytes activated by different levels of human phospholipase C zeta. Human Reproduction 23(2), pp. 365-373. (10.1093/humrep/dem350)

2006

Campbell, K. and Swann, K. 2006. Ca2+ oscillations stimulate an ATP increase during fertilization of mouse eggs. Developmental Biology 298(1), pp. 225-233. (10.1016/j.ydbio.2006.06.032)

2005

Nomikos, M.et al. 2005. Role of phospholipase C-zeta domains in Ca2+-dependent phosphatidylinositol 4,5-bisphosphate hydrolysis and cytoplasmic Ca2+ oscillations. Journal of biological chemistry 280(35), pp. 31011-31018. (10.1074/jbc.M500629200)

2004

Rogers, N. T.et al. 2004. Phospholipase Cζ causes Ca2+ oscillations and parthenogenetic activation of human oocytes. Reproduction 128(6), pp. 697-702. (10.1530/rep.1.00484)
Larman, M. G.et al. 2004. Cell cycle-dependent Ca2+ oscillations in mouse embryos are regulated by nuclear targeting of PLCzeta. Journal of cell science 117(12), pp. 2513-2521. (10.1242/jcs.01109)

2002

Saunders, C. M.et al. 2002. PLC zeta: a sperm-specific trigger of Ca(2+) oscillations in eggs and embryo development. Development 129(15), pp. 3533-3544.

A major theme in my research is to answer the fundamental question of how the sperm activates the egg at fertilization. At fertilization in all mammals the sperm initiates development by causing a series of oscillations in the cytosolic Ca²⁺ concentration. We have previously shown that the sperm initiates Ca²⁺ oscillations in egg by introducing the sperm specific phospholipase C zeta (PLCzeta) after gamete membrane fusion. PLCzeta generates cycles of InsP₃ production and Ca²⁺ release. We have shown that PLCzeta is unique amongst mammalian PLCs in causing Ca²⁺ oscillations in eggs, and in that it specifically targets intracellular vesicles containing phosphoinositides. Recent studies in mice suggest that there may be an additional factor that promotes Ca²⁺ oscillations in eggs and we have begun to investigate the nature of a putative second sperm factor.

We are currently investigating exactly how PLCzeta causes Ca²⁺ release and what factors in the egg effect the sensitivity to PLCzeta. We study egg activation in mouse eggs and collaborate with the Wales Fertility Institute to study Ca²⁺ oscillations in human eggs. I also collaborate with Thomas Woolley and Katerina Kaouri in the School of Mathematics in Cardiff University to model the mechanisms of Ca²⁺ oscillations. One of the main aims of these projects is to establish methods for improving egg activation and subsequent embryo development in clinical IVF treatments.

I am also interested in metabolism in eggs and early embryos and specifically in the regulation of mitochondrial activity. I collaborate with Paola Borri and Wolfgang Langbein (Physics, Cardiff University) and use CARS imaging of eggs and embryos to monitor changes in lipid droplets caused by exposure to fatty acids. We study the way in which lipid content effects egg and embryo physiology. We also study the mechanism and function of sperm induced mitochondrial ATP production at fertilization.

Collaborators

Prof Paola Borri - Cardiff University

Thomas Woolley - Cardiff University

Dr Paul Knaggs - Wales Fertility Institute

Current Lab Members

Dr Yisu Wang (postdoc)

Miss Cindy Ikie (PhD student)

Meysydd arbenigol

Proffiliau allanol

ORCID

Unedau Ymchwil

Biofeddygaeth