The influence of spectral composition on spring and autumn phenology in trees

Several recent reviews highlight the molecular mechanisms that underpin phenological responses to temperature and photoperiod; however, these have mostly overlooked the influence of solar radiation and its spectral composition on these processes. For instance, solar radiation in the blue and ultraviolet (UV) regions of the spectrum, as well as the red/far-red (R:FR) ratio, can influence spring and autumn phenology. Solar radiation reaching the Earth changes diurnally and seasonally; however, rising global temperatures, latitudinal range shifts and light pollution are likely to produce novel combinations of phenological cues for tree species. Here, we review the literature on phenological responses to spectral composition. Our objective was to explore the natural variation in spectral composition using radiative transfer models and to reveal any species-specific or ecotype-specific responses relating to latitudinal origin. These responses are likely to be most pronounced at high latitudes where spectral composition varies most throughout the year. For instance, trees from high latitudes tend to be more sensitive to changes in R:FR than those from low latitudes. The effects of blue light and UV radiation on phenology have not been studied as much as those of R:FR, but the limited results available suggest both could be candidate cues affecting autumn leaf colouration and senescence. Failure of more–southern species and ecotypes to adapt and use spectral cues during northwards range shifts could result in mistimed phenology, potentially resulting in frost damage, reduced fitness and limited range expansion. Future areas for research should look to establish how consistently different functional types of tree respond to spectral cues and identify photoreceptor-mediated mechanisms that allow plants to combine information from multiple light cues to coordinate the timing of phenological events. It should then be feasible to consider the synchronous or sequential action of light cues within a hierarchy of environmental factors regulating phenology.Peer reviewe

Under the influence of the market: an applied study of illicitly selling and consuming heroin

Illicit market activities are associated with considerable financial and psychological harms for drug users and third parties, and impose significant demands on public services. Since policy interventions interact with the market, evaluations of cost-effectiveness necessitate knowledge of how the market operates. There seems to be emerging consensus in the economic literature that economic factors, such as prices, can influence consumption patterns of addictive commodities. However, the descriptive validity of the notion of ‘maintenance doses’ have provided the rationale for predictions about the shape of the demand curve, and particularly for changes in slope, or ‘kinks’. Data collected from over 500 heroin users contacted outside a needle exchange service in Oslo are analysed in this paper. Wide variation in levels of consumption, income and prices are reported. Using a switching regression model of heroin consumption with endogenous switching between dealing and non-dealing, the influences if economic factors on the decision to deal and the level of consumption are estimated. Drug users in employment are estimated to be almost half as likely to sell drugs and a 10% increase in non-dealing income is estimated to reduce the probability of dealing by 3%. Non-dealing users’ consumption patterns are found to be price-elastic (elasticity = 1.23) and significantly influenced by the level of personal income (elasticity = 0.47). Influences on the extent of drug sales are also considered. Whilst appearing less responsive, dealers’ market activities have predictable relationships with economic factors and market conditions. For example, a 10% increase in the proportion of active dealers arrested in the previous month is found to reduce the size of the dealing population by over 3%. There is, however, some evidence that the remaining dealers are more active, such that attempts by enforcement agencies to reduce the size of the overall market are offset. No evidence of kinks in the demand curve for heroin are identified for the range of prices quoted on the Oslo market over a 13-month period. Given the multitude of influences on both the costs and benefits of consumption and the observed heterogeneity of drug users and their patterns of behaviour, this may not be surprising. The high price responsiveness of non-dealers’ heroin consumption and the importance of income levels in predicting behaviour emphasises the importance of policies which succeed in manipulating the economic conditions faced by illicit heroin users.drugs, heroin, addiction

A comparative study of WASP-67b and HAT-P-38b from WFC3 data

Atmospheric temperature and planetary gravity are thought to be the main parameters affecting cloud formation in giant exoplanet atmospheres. Recent attempts to understand cloud formation have explored wide regions of the equilibrium temperature-gravity parameter space. In this study, we instead compare the case of two giant planets with nearly identical equilibrium temperature ($T_\mathrm{eq}$ $\sim 1050 \, \mathrm{K}$) and gravity ($g \sim 10 \, \mathrm{m \, s}^{-1})$. During $HST$ Cycle 23, we collected WFC3/G141 observations of the two planets, WASP-67 b and HAT-P-38 b. HAT-P-38 b, with mass 0.42 M$_\mathrm{J}$ and radius 1.4 $R_\mathrm{J}$, exhibits a relatively clear atmosphere with a clear detection of water. We refine the orbital period of this planet with new observations, obtaining $P = 4.6403294 \pm 0.0000055 \, \mathrm{d}$. WASP-67 b, with mass 0.27 M$_\mathrm{J}$ and radius 0.83 $R_\mathrm{J}$, shows a more muted water absorption feature than that of HAT-P-38 b, indicating either a higher cloud deck in the atmosphere or a more metal-rich composition. The difference in the spectra supports the hypothesis that giant exoplanet atmospheres carry traces of their formation history. Future observations in the visible and mid-infrared are needed to probe the aerosol properties and constrain the evolutionary scenario of these planets.Comment: 16 pages, 17 figures, 8 tables, accepted for publication in The Astronomical Journa

Assessing the response of plant flavonoids to UV radiation : an overview of appropriate techniques

Flavonoids are a large group of plant secondary metabolites that are present in most plants, and are vital for plant growth, development and protection. Among the many functions of these compounds is their contribution to stress amelioration. The accurate identification and quantification of total or individual flavonoids in plants exposed to stressful conditions (e.g. ultraviolet radiation) is challenging due to their structural diversity. The present review provides the up to date knowledge and highlights trends in plant flavonoid analysis. The review covers all steps from the field to the laboratory, focussing on UV-B effects on flavonoids, and identifying critical issues concerning sample collection, pre-treatment, extraction techniques and quantitative or qualitative analysis. A well-planned sampling and sample prehandling strategy is vital when capturing organ, tissue and developmental-stage dependent changes in flavonoids, as well as the dynamic changes due to time of UV-exposure and diurnal or seasonal parameters. A range of advanced extraction and purification techniques can facilitate the quantitative transfer of flavonoids to solvents. The advantages and disadvantages of analytical methods, including chromogenic assays, liquid and thin-layer chromatography, mass spectrometry, nuclear magnetic resonance detection, and non-destructive in situ fluorescent analysis need to be consciously evaluated in the context of the specific biological question posed. Thus, no one method can be applied to every single study of flavonoid. The message of this review is that researchers will need to carefully consider the biological process that they intend to study, and select an analytical method that optimally matches their specific objectives.Peer reviewe

Non-essential genes form the hubs of genome scale protein function and environmental gene expression networks in Salmonella enterica serovar Typhimurium

Background Salmonella Typhimurium is an important pathogen of human and animals. It shows a broad growth range and survives in harsh conditions. The aim of this study was to analyze transcriptional responses to a number of growth and stress conditions as well as the relationship of metabolic pathways and/or cell functions at the genome-scale-level by network analysis, and further to explore whether highly connected genes (hubs) in these networks were essential for growth, stress adaptation and virulence. Results De novo generated as well as published transcriptional data for 425 selected genes under a number of growth and stress conditions were used to construct a bipartite network connecting culture conditions and significantly regulated genes (transcriptional network). Also, a genome scale network was constructed for strain LT2. The latter connected genes with metabolic pathways and cellular functions. Both networks were shown to belong to the family of scale-free networks characterized by the presence of highly connected nodes or hubs which are genes whose transcription is regulated when responding to many of the assayed culture conditions or genes encoding products involved in a high number of metabolic pathways and cell functions. The five genes with most connections in the transcriptional network (wraB, ygaU, uspA, cbpA and osmC) and in the genome scale network (ychN, siiF (STM4262), yajD, ybeB and dcoC) were selected for mutations, however mutagenesis of ygaU and ybeB proved unsuccessful. No difference between mutants and the wild type strain was observed during growth at unfavorable temperatures, pH values, NaCl concentrations and in the presence of H2O2. Eight mutants were evaluated for virulence in C57/BL6 mice and none differed from the wild type strain. Notably, however, deviations of phenotypes with respect to the wild type were observed when combinations of these genes were deleted. Conclusion Network analysis revealed the presence of hubs in both transcriptional and functional networks of S. Typhimurium. Hubs theoretically confer higher resistance to random mutation but a greater susceptibility to directed attacks, however, we found that genes that formed hubs were dispensable for growth, stress adaptation and virulence, suggesting that evolution favors non-essential genes as main connectors in cellular networks

Ultraviolet radiation accelerates photodegradation under controlled conditions but slows the decomposition of senescent leaves from forest stands in southern Finland

Depending on the environment, sunlight can positively or negatively affect litter decomposition, through the ensemble of direct and indirect processes constituting photodegradation. Which of these processes predominate depends on the ecosystem studied and on the spectral composition of sunlight received. To examine the relevance of photodegradation for litter decomposition in forest understoreys, we filtered ultraviolet radiation (UV) and blue light from leaves of Fagus sylvatica and Bettda pendula at two different stages of senescence in both a controlled-environment experiment and outdoors in four different forest stands (Picea abies, Pagus sylvatica, Acer platanoides, Betula pendula). Controlling for leaf orientation and initial differences in leaf chlorophyll and flavonol concentrations; we measured mass loss at the end of each experiment and characterised the phenolic profile of the leaf litter following photodegradation. In most forest stands, less mass was lost from decomposing leaves that received solar UV radiation compared with those under UV-attenuating filters, while in the controlled environment UV-A radiation either slightly accelerated or had no significant effect on photodegradation, according to species identity. Only a few individual phenolic compounds were affected by our different filter treatments, but photodegradation did affect the phenolic profile. We can conclude that photodegradation has a small stand- and species-specific effect on the decomposition of surface leaf litter in forest understoreys during the winter following leaf fall in southern Finland. Photodegradation was wavelength-dependent and modulated by the canopy species filtering sunlight and likely creating different combinations of spectral composition, moisture, temperature and snowpack characteristics.Peer reviewe

Saffron extract (Safr’InsideTM) improves anxiety related behaviour in a mouse model of low-grade inflammation through the modulation of the microbiota and gut derived metabolites

Treatment of anxiety and depression predominantly centres around pharmacological interventions, which have faced criticism for their associated side effects, lack of efficacy and low tolerability. Saffron, which is reportedly well tolerated in humans, has been recognised for its antidepressant and anti-anxiety properties. Indeed, we previously reported upon the efficacy of saffron extract supplementation in healthy adults with subclinical anxiety. However, the molecular aetiology remains unclear. In a rodent model of low-grade chronic inflammation, we explored the impact of a saffron extract (Safr’InsideTM) supplementated at a physiological dose, which equated to 22 ± 1.2 mg per day human equivalent dose for a person of 60 Kg. Behavioural tests (Open field task, Y maze, Novel object recognition), caecal 16S rRNA microbial sequencing, caecal 1H NMR metabolomic analysis and 2DE brain proteomic analyses were completed to probe gut-brain axis interactions. Time occupying the centre of the Open field maze (OF) was increased by 62% in saffron supplemented animals. This improvement in anxiety-related behaviour coincided with gut microbial shifts, notably Akkermansia, Muribaculaceae, Christensenellacae and Alloprevotella which significantly increased in response to saffron supplementation. Akkermansia and Muribaculaceae abundance negatively correlated with the neurotoxic metabolite dimethylamine which was reduced in saffron supplemented animals. Brain proteomic analysis highlighted several significantly altered proteins including ketimine reductase mu-crystallin which also correlated with dimethylamine concentration. Both dimethylamine and ketimine reductase mu-crystallin were associated with OF performance. This may be indicative of a novel interaction across the gut-brain axis which contributes to anxiety-related disorders