@article{love_scott_thompson_2000, title={Stringent control of transgene expression in Arabidopsis thaliana using the Top10 promoter system}, volume={21}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313x.2000.00706.x}, abstractNote={SummaryWe show that the tightly regulated tetracycline‐sensitive Top10 promoter system (Weinmann et al. Plant J. 1994, 5, 559–569) is functional in Arabidopsis thaliana. A pure breeding A. thaliana line (JL‐tTA/8) was generated which expressed a chimeric fusion of the tetracycline repressor and the activation domain of Herpes simplex virus (tTA), from a single transgenic locus. Plants from this line were crossed with transgenics carrying the ER‐targeted green fluorescent protein coding sequence (mGFP5) under control of the Top10 promoter sequence. Progeny from this cross displayed ER‐targeted GFP fluorescence throughout the plant, indicating that the tTA–Top10 promoter interaction was functional in A. thaliana. GFP expression was repressed by 100 ng ml−1 tetracycline, an order of magnitude lower than the concentration used previously to repress expression in Nicotiana tabacum. Moreover, the level of GFP expression was controlled by varying the concentration of tetracycline in the medium, allowing a titred regulation of transgenic activity that was previously unavailable in A. thaliana. The kinetics of GFP activity were determined following de‐repression of the Top10::mGFP5 transgene, with a visible ER‐targeted GFP signal appearing from 24 to 48 h after de‐repression.}, number={6}, journal={PLANT JOURNAL}, author={Love, J and Scott, AC and Thompson, WF}, year={2000}, month={Mar}, pages={579–588} }
 @article{scott_allen_1999, title={Changes in cytosolic pH within Arabidopsis root columella cells play a key role in the early signaling pathway for root gravitropism}, volume={121}, ISSN={["1532-2548"]}, DOI={10.1104/pp.121.4.1291}, abstractNote={Abstract
               Ratiometric wide-field fluorescence microscopy with 1′,7′- bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran demonstrated that gravistimulation leads to rapid changes in cytoplasmic pH (pHc) in columella cells of Arabidopsis roots. The pHc of unstimulated columella cells in tiers 2 and 3, known sites of graviperception (E.B. Blancaflor, J.B. Fasano, S. Gilroy [1998] Plant Physiol 116: 213–222), was 7.22 ± 0.02 pH units. Following gravistimulation, the magnitude and direction of pHc changes in these cells depended on their location in the columella. Cells in the lower side of tier 2 became more alkaline by 0.4 unit within 55 s of gravistimulation, whereas alkalinization of the cells on the upper side was slower (100 s). In contrast, all cells in tier 3 acidified by 0.4 pH unit within 480 s after gravistimulation. Disrupting these pHc changes in the columella cells using pHc modifiers at concentrations that do not affect root growth altered the gravitropic response. Acidifying agents, including bafilomycin A1, enhanced curvature, whereas alkalinizing agents disrupted gravitropic bending. These results imply that pHc changes in the gravisensing cells and the resultant pH gradients across the root cap are important at an early stage in the signal cascade leading to the gravitropic response.}, number={4}, journal={PLANT PHYSIOLOGY}, author={Scott, AC and Allen, NS}, year={1999}, month={Dec}, pages={1291–1298} }