Previous PhD students in the lab created a method for large-scale, high-content microscopy screening of a cell library consisting of over 3000 single mutant strains of the fission yeast, Schizosaccharomyces pombe. Each strain has one nonessential gene knocked-out, allowing investigation of the resulting phenotypes. I report the implementation and completion of this screen; developing methods to ensure reliable and accurate results through inclusion of many controls across multiple screening repeats. In total, over 4.5 million images from approximately 19 000 biologically independent cell populations were imaged and analysed. All strains screened contained GFP-labelled tubulin (GFP-Atb2) allowing visualisation of the microtubule polymer network and its organisation in cells, a feature that is conserved across eukaryotes and simplified in S. pombe, making it easy to study. Examination of cell outlines and microtubule patterns was used to study three cell processes: the shape of cells, the organisational pattern of interphase microtubules and the cell cycle stage of cells, as judged by microtubule pattern. Comparison with extensive data from wild-type cells led to the identification of 262 factors that influence one or more of these cell processes. I go on to biologically validate some of the outcomes from the screen, leading to a publication in Developmental Cell reporting the screen, its findings and the online genomic resource SYSGRO. I then focus on a group of mutants that suggest a connection between the DNA damage response (DDR) and microtubule organisation. From here I show that the DDR induces elongation of microtubule bundles in response to the DDR kinases, ATM and ATR. I begin to reveal factors that may mediate this response and finally, I provide evidence to suggest that the same mechanism is conserved in cultured human cells (Hc3716-hTERT), which may go some way to explaining clinical results showing a beneficial effect of microtubule destabilisation in conjunction with cancer therapies.

<p> <b>Aims:</b> Propofol, clinically named as Diprivan is an intravenous anesthetic known to cause hypotension in patients presenting for surgery. We have investigated the vasodilatory signaling cascade by which propofol causes hypotension using both <i>in vivo</i> and <i>in vitro </i> experimental approaches. </p><p> <b>Methods and Results:</b> Using high-fidelity microtip transducer catheter, mean arterial blood pressure (MAP) was measured in control, transient receptor potential ankyrin subtype 1 knock-out (TRPA1^-/-), transient receptor potential vanilloid 1 knock-out (TRPV1^-/-) and TRPA1-TRPV1 double-knockout mice (TRPAV^-/-) in the presence and absence of L-NAME (an endothelial nitric oxide synthase inhibitor) and penitrem A [a big-conductance calcium gated (BK_Ca) channel inhibitor]. To further support our <i>in-vivo</i> data, murine coronary microvessels were isolated and cannulated for vasoreactivity studies. Furthermore, NO production from endothelial cells isolated from mouse aorta was also measured and immunocytochemical (ICC) studies were performed to show the intracellular localization of TRPA1 and TRPV1. Our <i>in-vivo</i> data shows that the characteristic propofol-induced depressor response is dependent on TRPA1-NO-BK_Ca pathway. Interestingly, vasoreactivity studies in isolated murine left anterior ascending (LAD) arteries demonstrate that TRPA1 and TRPV1 communicate with each other and propofol-induced vasodilation is dependent on both TRPA1 and TRPV1. Moreover our data also suggest that NO production and BK channel activation are the downstream mediators in this pathway. Finally, we demonstrate that NO production is attenuated in primary endothelial cells isolated from TRPAV^-/- mice. ICC data also shows the co-localization of these channels in mouse aortic endothelial cells. </p><p> <b>Conclusions: </b>This is the first study which has shown that propofol-induced vasodilation involves TRPA1 <i>in-vivo</i> and also there is an implication of cross-talk between TRPA1 and TRPV1 in the coronary bed. Furthermore by understanding the mechanisms by which this anesthetic causes hypotension and coronary dilation will help to mitigate the potential harmful side-effects of anesthesia in patients with little cardiovascular reserve. This will in turn ensure a better and faster post-operative recovery in patients, especially benefiting those suffering from diabetes and other cardiovascular disorders.</p>

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