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Light intensity and atmospheric CO2 partial pressure are two environmental signals known to regulate stomatal numbers. It has previously been shown that if a mature Arabidopsis leaf is supplied with either elevated CO2 (750 ppm instead of ambient at 370 ppm) or reduced light levels (50 μmol m−2 s−1 instead of 250 μmol m−2 s−1), the young, developing leaves that are not receiving the treatment grow with a stomatal density as if they were exposed to the treatment. But the signal(s) that it is believed is generated in the mature leaves and transmitted to developing leaves are largely unknown. Photosynthetic rates of treated, mature Arabidopsis leaves increased in elevated CO2 and decreased when shaded, as would be expected. Similarly, the levels of sugars (glucose, fructose, and sucrose) in the treated mature leaves increased in elevated CO2 and decreased with shade treatment. The levels of sugar in developing leaves were also measured and it was found that they mirrored this result even though they were not receiving the shade or elevated CO2 treatment. To investigate the effect of these treatments on global gene expression patterns, transcriptomics analysis was carried out using Affymetrix, 22K, and ATH1 arrays. Total RNA was extracted from the developing leaves after the mature leaves had received either the ambient control treatment, the elevated CO2 treatment, or the shade treatment, or both elevated CO2 and shade treatments for 2, 4, 12, 24, 48, or 96 h. The experiment was replicated four times. Two other experiments were also conducted, one to compare and contrast gene expression in response to plants grown at elevated CO2 and the other to look at the effect of these treatments on the mature leaf. The data were analysed and 915 genes from the untreated, signalled leaves were identified as having expression levels affected by the shade treatment. These genes were then compared with those whose transcript abundance was affected by the shade treatment in the mature treated leaves (1181 genes) and with 220 putative ‘stomatal signalling’ genes previously identified from studies of the yoda mutant. The results of these experiments and how they relate to environmental signalling are discussed, as well as possible mechanisms for systemic signalling. [ABSTRACT FROM PUBLISHER]

Stomatal numbers are tightly controlled by environmental signals including light intensity and atmospheric CO2 partial pressure. This requires control of epidermal cell development during the early phase of leaf growth and involves changes in both the density of cells on the leaf surface and the proportion of cells that adopt a stomatal fate. This paper reviews the current understanding of how stomata develop and describes recent advances that have given insights into the regulatory mechanisms involved using mutant Arabidopsis plants that implicates a role for long-chain fatty acids in cell-to-cell communication. Evidence is presented which indicates that long-distance signalling from mature to newly developing leaves forms part of the mechanism by which stomatal development responds to environmental cues. Analysis of mutant plants suggests that the plant hormones abscisic acid, ethylene and jasmonates are implicated in the long-distance signalling pathway and that the action may be mediated by reactive oxygen species. [ABSTRACT FROM AUTHOR]

Introduction: In contrast to other medical specialties, trainees in Geriatrics have historically provided an increased contribution to clinical workload in General Internal Medicine and a reduced output of academic achievements. More recently, development of non-clinical skills has been recognised to have similar importance to clinical skills and the South East (SE) London Geriatrics Training Programme has thus supported trainees in applications for Out of Programme (OOP) opportunities to optimise career progression. Methods: Doctors who had undertaken specialist registrar training in the SE London Geriatrics Training Programme at any time between 2011 and 2019 were sent a questionnaire to assess whether they had completed time OOP and whether they had been awarded research grants, published papers in peer-reviewed journals, had abstracts accepted for presentation at conferences, and/or published book chapters during their training programme. Chisquared and Wilcoxon rank-sum tests were used to compare data between registrars who had completed time OOP and those who had not taken time OOP. Results: 77 (24 male; 53 female) registrars completed training in the SE London Geriatrics Training Programme between 2011 and 2019. 71 registrars (92%) completed the questionnaire, of whom 31 (44%) completed time OOP. In total, registrars were awarded 15 research grants, published 86 papers in peer-reviewed journals, had abstracts accepted for 184 conference presentations and published 20 book chapters. A notably increased proportion of registrars who took time OOP had an output of research grants, papers published in peer reviewed journals, abstracts accepted for presentation at conferences and/or book chapters respectively compared with registrars who had not taken time OOP (23% vs 5% ; 61% vs 23%; 84% vs 33%; 45% vs 5%). This equated to a combined academic output in 94% of registrars who completed time OOP compared with 48% who did not (p <0.001). Conclusions: A very strong association existed between registrars in Geriatrics taking time OOP and academic achievement substantiating the training programme’s aspiration to support development of non-clinical skills that may be helpful to trainees in their future careers. It would be worthwhile further work being undertaken in this area in other regions. [ABSTRACT FROM AUTHOR]