Drug-like, donor–acceptor diphenylacetylenes cause efficient cell death upon photoactivation and hence have potential phototherapeutic applications.

Retinoids, such as all-trans-retinoic acid (ATRA), are endogenous signaling molecules derived from vitamin A that influence a variety of cellular processes through mediation of transcription events in the cell nucleus. Because of these wide-ranging and powerful biological activities, retinoids have emerged as therapeutic candidates of enormous potential. However, their use has been limited, to date, due to a lack of understanding of the complex and intricate signaling pathways that they control. We have designed and synthesized a family of synthetic retinoids that exhibit strong, intrinsic, solvatochromatic fluorescence as multifunctional tools to interrogate these important biological activities. We utilized the unique photophysical characteristics of these fluorescent retinoids to develop a novel in vitro fluorometric binding assay to characterize and quantify their binding to their cellular targets, including cellular retinoid binding protein II (CRABPII). The dihydroquinoline retinoid, DC360, exhibited particularly strong binding (K d = 34.0 ± 2.5 nM), and we further used X-ray crystallography to determine the structure of the DC360–CRABPII complex to 1.8 Å, which showed that DC360 occupies the known hydrophobic retinoid binding pocket. Finally, we used confocal fluorescence microscopy to image the cellular behavior of the compounds in cultured human epithelial cells, highlighting a fascinating nuclear localization, and used RNA sequencing to confirm that the compounds regulate cellular processes similar to those of ATRA. We anticipate that the unique properties of these fluorescent retinoids can now be used to cast new light on the vital and highly complex retinoid signaling pathway.

Extreme weather and globalisation leave our climate vulnerable to invasion by alien species, which have negative impacts on the economy, biodiversity, and ecosystem services. Rapid and accurate identification is key to the control of invasive alien species. However, visually similar species hinder conservation efforts, for example hybrids within the Japanese Knotweed complex. We applied the novel method of ATR-FTIR spectroscopy combined with chemometrics (mathematics applied to chemical data) to historic herbarium samples, taking 1580 spectra in total. Samples included five species from within the interbreeding Japanese Knotweed complex (including three varieties of Japanese Knotweed), six hybrids and five species from the wider Polygonaceae family. Spectral data from herbarium specimens were analysed with several chemometric techniques: support vector machines (SVM) for differentiation between plant types, supported by ploidy levels; principal component analysis loadings and spectral biomarkers to explore differences between the highly invasive Reynoutria japonica var. japonica and its non-invasive counterpart Reynoutria japonica var. compacta; hierarchical cluster analysis (HCA) to investigate the relationship between plants within the Polygonaceae family, of the Fallopia, Reynoutria, Rumex and Fagopyrum genera. ATR-FTIR spectroscopy coupled with SVM successfully differentiated between plant type, leaf surface and geographical location, even in herbarium samples of varying age. Differences between Reynoutria japonica var. japonica and Reynoutria japonica var. compacta included the presence of two polysaccharides, glucomannan and xyloglucan, at higher concentrations in Reynoutria japonica var. japonica than Reynoutria japonica var. compacta. HCA analysis indicated that potential genetic linkages are sometimes masked by environmental factors; an effect that can either be reduced or encouraged by altering the input parameters. Entering the absorbance values for key wavenumbers, previously highlighted by principal component analysis loadings, favours linkages in the resultant HCA dendrogram corresponding to expected genetic relationships, whilst environmental associations are encouraged using the spectral fingerprint region. The ability to distinguish between closely related interbreeding species and hybrids, based on their spectral signature, raises the possibility of using this approach for determining the origin of Japanese knotweed infestations in legal cases where the clonal nature of plants currently makes this difficult and for the targeted control of species and hybrids. These techniques also provide a new method for supporting biogeographical studies.

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Background Japanese knotweed (R. japonica var japonica) is one of the world’s 100 worst invasive species, causing crop losses, damage to infrastructure, and erosion of ecosystem services. In the UK, this species is an all-female clone, which spreads by vegetative reproduction. Despite this genetic continuity, Japanese knotweed can colonise a wide variety of environmental habitats. However, little is known about the phenotypic plasticity responsible for the ability of Japanese knotweed to invade and thrive in such diverse habitats. We have used attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, in which the spectral fingerprint generated allows subtle differences in composition to be clearly visualized, to examine regional differences in clonal Japanese knotweed. Results We have shown distinct differences in the spectral fingerprint region (1800–900 cm− 1) of Japanese knotweed from three different regions in the UK that were sufficient to successfully identify plants from different geographical regions with high accuracy using support vector machine (SVM) chemometrics. Conclusions These differences were not correlated with environmental variations between regions, raising the possibility that epigenetic modifications may contribute to the phenotypic plasticity responsible for the ability of R. japonica to invade and thrive in such diverse habitats.

Smith's technique (constant 1.31) provided an ACD that is closer to that found with Orbscan compared to a constant of 1.40 or LCDvh. Our findings also suggest that Smith's technique would produce values closer to that obtained with Orbscan by using a constant of 1.22.

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Plants have evolved complex signalling networks in order to respond to the plethora of environmental and developmental stimuli to which they are exposed. Within these networks, a diverse range of signals are integrated, allowing the plant to formulate an appropriate response to the prevailing conditions. An important feature of signalling pathways into networks is the potential for pathways to interact with each other, thereby influencing the responses observed. This is known as crosstalk. Signalling networks act through a hub and spoke model where the hub is a key determinant of the pathways that will crosstalk with one another. Reactive oxygen species (ROS) are an example of such a signalling hub that play an intrinsic role in crosstalk within plant stress signalling networks. ROS are of particular interest due to their ability to have positive or negative effects, depending on their abundance within the cell. Key Concepts Plants employ complex signalling networks in their responses to environmental and developmental stimuli, transducing a wide range of signals from the point of perception, typically via a receptor, to a diverse array of effectors. Signalling can occur via a range of intermediates (chemical, electrical or hydraulic) including well‐characterised secondary messenger compounds. Crosstalk can occur between signalling pathways when one or more of these components interact with each other. ROS are important signalling molecules, essential for plant cell homeostasis and the regulation of vital plant responses, such as reaction to abiotic and biotic stress, hormone signalling and the regulation of growth. ROS can have a positive or negative effect within a cell, acting as either a toxic by‐product of aerobic respiration within cells or essential signalling molecules through their role as an indispensable hub in plant signalling networks.