Caught in the act: Implications for the increasing abundance of mafic enclaves during the eruption of the Soufriere Hills Volcano, Montserrat

An exceptional opportunity to sample several large blocks sourced from the same region of the growing Soufrière Hills lava dome has documented a significant increase in the presence of mafic enclaves in the host andesite during the course of a long-lived eruptive episode with several phases. In 1997 (Phase I) mafic inclusions comprised ~1 volume percent of erupted material; in 2007 (Phase III) deposits their volumetric abundance increased to 5–7 percent. A broader range of geochemically distinctive types occurs amongst the 2007 enclaves. Crystal-poor enclaves generally have the least evolved (basaltic) compositions; porphyritic enclaves represent compositions intermediate between basaltic and andesitic compositions. The absence of porphyritic enclaves prior to Phase III magmatism at Soufrière Hills Volcano suggests that a mixing event occurred during the course of the current eruptive episode, providing direct evidence consistent with geophysical observations that the system is continuously re-invigorated from depth

Glutathione – linking cell proliferation to oxidative stress

Significance: The multifaceted functions of reduced glutathione (gamma-glutamyl-cysteinyl-glycine; GSH) continue to fascinate plants and animal scientists, not least because of the dynamic relationships between GSH and reactive oxygen species (ROS) that underpin reduction/oxidation (redox) regulation and signalling. Here we consider the respective roles of ROS and GSH in the regulation of plant growth, with a particular focus on regulation of the plant cell cycle. Glutathione is discussed not only as a crucial low molecular weight redox buffer that shields nuclear processes against oxidative challenge but also a flexible regulator of genetic and epigenetic functions. Recent Advances: The intracellular compartmentalization of GSH during the cell cycle is remarkably consistent in plants and animals. Moreover, measurements of in vivo glutathione redox potentials reveal that the cellular environment is much more reducing than predicted from GSH/GSSG ratios measured in tissue extracts. The redox potential of the cytosol and nuclei of non-dividing plant cells is about -300 mV. This relatively low redox potential is maintained even in cells experiencing oxidative stress by a number of mechanisms including vacuolar sequestration of GSSG. We propose that regulated ROS production linked to glutathione-mediated signalling events are the hallmark of viable cells within a changing and challenging environment. Critical Issues: The concept that the cell cycle in animals is subject to redox controls is well established but little is known about how ROS and GSH regulate this process in plants. However, it is increasingly likely that similar redox controls exist in plants, although possibly through different pathways. Moreover, redox-regulated proteins that function in cell cycle checkpoints remain to be identified in plants. While GSH-responsive genes have now been identified, the mechanisms that mediate and regulate protein glutathionylation in plants remain poorly defined. Future Directions: The nuclear GSH pool provides an appropriate redox environment for essential nuclear functions. Future work will function on how this essential thiol interacts with the nuclear thioredoxin system and nitric oxide to regulate genetic and epigenetic mechanisms. The characterization of redox-regulated cell cycle proteins in plants, and the elucidation of mechanisms that facilitate GSH accumulation in the nucleus are keep steps to unravelling the complexities of nuclear redox controls

Wound-induced increases in the glucosinolate content of oilseed rape and their effect on subsequent herbivory by a crucifer specialist

Damage to the oilseed rape plant (Brassica napus L.) by the cabbage stem flea beetle, Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) induces systemic changes to the glucosinolate profile, most noticeably an increase in the concentration of indole glucosinolates. When jasmonic acid was applied to the cotyledons of the plant, a similar effect was observed. Feeding tests with artificial substrates compared a glucosinolate fraction from jasmonic acid-treated plants with a similar fraction from untreated plants. In these tests, alterations to the glucosinolate profile increased the feeding of a crucifer-specialist feeder (P. chrysocephala). However, in whole plant tests, P. chrysocephala did not feed more on the jasmonic acid treated plants than on the controls. This implies that other aspects of the damage response are being induced by the jasmonic acid treatment and having a negative effect on subsequent herbivory

Control of Ascorbate Synthesis by Respiration and Its Implications for Stress Responses

We show for the first time that respiration can control ascorbate (AA) synthesis in plants. Evidence for this control is provided by (a) the localization of L-galactono-1,4-lactone dehydrogenase (GalLDH), the terminal enzyme in AA biosynthesis, with mitochondrial complex I, and its regulation by electron transport through this complex, (b) the absolute requirement of the enzyme for oxidized cytochrome c (cyt c(ox)) as substrate, and (c) the coordinated response of respiration and AA synthesis to stress induced by hormone treatment.Instituto de Fisiología VegetalFacultad de Ciencias Agrarias y Forestale

Optimised LAMP allows single copy detection of 35Sp and NOSt in transgenic maize using Bioluminescent Assay in Real Time (BART)

Loop-mediated amplification (LAMP) has been widely used to amplify and hence detect nucleic acid target sequences from various pathogens, viruses and genetic modifications. Two distinct types of primer are required for LAMP; hairpin-forming LAMP and displacement. High specificity arises from this use of multiple primers, but without optimal conditions for LAMP, sensitivity can be poor. We confirm here the importance of LAMP primer design, concentrations and ratios for efficient LAMP amplification. We further show that displacement primers are non-essential to the LAMP reaction at certain concentrations providing accelerating loop primers are present. We investigate various methods to quantify DNA extracts from GM maize certified reference materials to calculate the target copy numbers of template presented to the LAMP reaction, and show that LAMP can amplify transgenic promoter / terminator sequences in DNA extracted from various maize GM events using primers designed to target the 35S promoter (35Sp) or NOS terminator (NOSt) sequences, detection with both bioluminescence in real-time (BART) and fluorescent methods. With prior denaturation and HPLC grade LAMP primers single copy detection was achieved, showing that optimised LAMP conditions can be combined with BART for single copy targets, with simple and cost efficient light detection electronics over fluorescent alternatives

High-resolution temporal profiling of transcripts during Arabidopsis leaf senescence reveals a distinct chronology of processes and regulation

Leaf senescence is an essential developmental process that impacts dramatically on crop yields and involves altered regulation of thousands of genes and many metabolic and signaling pathways, resulting in major changes in the leaf. The regulation of senescence is complex, and although senescence regulatory genes have been characterized, there is little information on how these function in the global control of the process. We used microarray analysis to obtain a highresolution time-course profile of gene expression during development of a single leaf over a 3-week period to senescence. A complex experimental design approach and a combination of methods were used to extract high-quality replicated data and to identify differentially expressed genes. The multiple time points enable the use of highly informative clustering to reveal distinct time points at which signaling and metabolic pathways change. Analysis of motif enrichment, as well as comparison of transcription factor (TF) families showing altered expression over the time course, identify clear groups of TFs active at different stages of leaf development and senescence. These data enable connection of metabolic processes, signaling pathways, and specific TF activity, which will underpin the development of network models to elucidate the process of senescence

Characteristics, service use and mortality of clusters of multimorbid patients in England: a population-based study

Abstract: Background: Multimorbidity is associated with mortality and service use, with specific types of multimorbidity having differential effects. Additionally, multimorbidity is often negatively associated with participation in research cohorts. Therefore, we set out to identify clusters of multimorbidity patients and how they are differentially associated with mortality and service use across age groups in a population-representative sample. Methods: Linked primary and secondary care electronic health records contributed by 382 general practices in England to the Clinical Practice Research Datalink (CPRD) were used. The study included a representative set of multimorbid adults (18 years old or more, N = 113,211) with two or more long-term conditions (a total of 38 conditions were included). A random set of 80% of the multimorbid patients (N = 90,571) were stratified by age groups and clustered using latent class analysis. Consistency between obtained multimorbidity phenotypes, classification quality and associations with demographic characteristics and primary outcomes (GP consultations, hospitalisations, regular medications and mortality) was validated in the remaining 20% of multimorbid patients (N = 22,640). Results: We identified 20 patient clusters across four age strata. The clusters with the highest mortality comprised psychoactive substance and alcohol misuse (aged 18–64); coronary heart disease, depression and pain (aged 65–84); and coronary heart disease, heart failure and atrial fibrillation (aged 85+). The clusters with the highest service use coincided with those with the highest mortality for people aged over 65. For people aged 18–64, the cluster with the highest service use comprised depression, anxiety and pain. The majority of 85+-year-old multimorbid patients belonged to the cluster with the lowest service use and mortality for that age range. Pain featured in 13 clusters. Conclusions: This work has highlighted patterns of multimorbidity that have implications for health services. These include the importance of psychoactive substance and alcohol misuse in people under the age of 65, of co-morbid depression and coronary heart disease in people aged 65–84 and of cardiovascular disease in people aged 85+

Plasma based markers of [11C] PiB-PET brain amyloid burden.

PublishedJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov'tChanges in brain amyloid burden have been shown to relate to Alzheimer's disease pathology, and are believed to precede the development of cognitive decline. There is thus a need for inexpensive and non-invasive screening methods that are able to accurately estimate brain amyloid burden as a marker of Alzheimer's disease. One potential method would involve using demographic information and measurements on plasma samples to establish biomarkers of brain amyloid burden; in this study data from the Alzheimer's Disease Neuroimaging Initiative was used to explore this possibility. Sixteen of the analytes on the Rules Based Medicine Human Discovery Multi-Analyte Profile 1.0 panel were found to associate with [(11)C]-PiB PET measurements. Some of these markers of brain amyloid burden were also found to associate with other AD related phenotypes. Thirteen of these markers of brain amyloid burden--c-peptide, fibrinogen, alpha-1-antitrypsin, pancreatic polypeptide, complement C3, vitronectin, cortisol, AXL receptor kinase, interleukin-3, interleukin-13, matrix metalloproteinase-9 total, apolipoprotein E and immunoglobulin E--were used along with co-variates in multiple linear regression, and were shown by cross-validation to explain >30% of the variance of brain amyloid burden. When a threshold was used to classify subjects as PiB positive, the regression model was found to predict actual PiB positive individuals with a sensitivity of 0.918 and a specificity of 0.545. The number of APOE [Symbol: see text] 4 alleles and plasma apolipoprotein E level were found to contribute most to this model, and the relationship between these variables and brain amyloid burden was explored.Alzheimer's Disease Neuroimaging Initiative (ADNI)Canadian Institutes of Health ResearchFoundation for the National Institutes of HealthNational Institutes of HealthInnoMed, European Union of the Sixth Framework programNational Institutes for Health Research Biomedical Research Centre for Mental Health at the South London and Maudsley National Health Service Foundation TrustInstitute of Psychiatry, King's College Londo