Ascorbate degradation in tomato leads to accumulation of oxalate, threonate and oxalyl threonate:Ascorbate degradation in tomato

Ascorbate content in plants is controlled by its synthesis from carbohydrates, recycling of the oxidized forms and degradation. Of these pathways, ascorbate degradation is the least studied and represents a lack of knowledge that could impair improvement of ascorbate content in fruits and vegetables as degradation is non-reversible and leads to a depletion of the ascorbate pool. The present study revealed the nature of degradation products using [C-14] ascorbate labelling in tomato, a model plant for fleshy fruits; oxalate and threonate are accumulated in leaves, as is oxalyl threonate. Carboxypentonates coming from diketogulonate degradation were detected in relatively insoluble (cell wall-rich) leaf material. No [C-14] tartaric acid was found in tomato leaves. Ascorbate degradation was stimulated by darkness, and the degradation rate was evaluated at 63% of the ascorbate pool per day, a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more. Furthermore, degradation could be partially affected by the ascorbate recycling pathway, as lines under-expressing monodehydroascorbate reductase showed a slight decrease in degradation product accumulation

Behavioural response of green peach aphid Myzus persicae (Sulzer) to volatiles from different rosemary (Rosmarinus officinalis L.) clones

Previous studies have shown that rosemary (Rosmarinus officinalis L.) can serve as a companion plant to control Myzus persicae (Sulzer) because of the repellent effect of certain volatile organic compounds (VOCs) that it emits. In the present study, we investigated which of five clones of rosemary may reveal a repellent effect on M. persicae and aimed to determine the possible VOCs involved.Analyses of the mixtures of VOCs released by the different clones revealed the presence of 15 main components. However, each clone was characterized by a specific volatile profile showing the existence of marked chemical variability.By testing the identified VOCs individually, using a dual‐choice olfactometer, we observed that five volatiles had a significant repulsive effect on M. persicae: bornyl acetate, camphor, α‐terpineol, terpinene‐4‐ol and geranyl acetone. In addition, only one clone of rosemary elicited a significant repulsive action.Nevertheless, all of the tested clones released compounds that are repellent to the aphid when tested individually. Therefore, the emission of individual volatiles by a rosemary plant is not sufficient to elicit a repellent effect.The concentration, proportion and even the association/synergy of VOCs in the released olfactory bouquets can probably explain these contrasting results and are worthy of additional exploration in future studies

The genomic basis of color pattern polymorphism in the Harlequin ladybird

© 2018 The Authors Many animal species comprise discrete phenotypic forms. A common example in natural populations of insects is the occurrence of different color patterns, which has motivated a rich body of ecological and genetic research [1–6]. The occurrence of dark, i.e., melanic, forms displaying discrete color patterns is found across multiple taxa, but the underlying genomic basis remains poorly characterized. In numerous ladybird species (Coccinellidae), the spatial arrangement of black and red patches on adult elytra varies wildly within species, forming strikingly different complex color patterns [7, 8]. In the harlequin ladybird, Harmonia axyridis, more than 200 distinct color forms have been described, which classic genetic studies suggest result from allelic variation at a single, unknown, locus [9, 10]. Here, we combined whole-genome sequencing, population-based genome-wide association studies, gene expression, and functional analyses to establish that the transcription factor Pannier controls melanic pattern polymorphism in H. axyridis. We show that pannier is necessary for the formation of melanic elements on the elytra. Allelic variation in pannier leads to protein expression in distinct domains on the elytra and thus determines the distinct color patterns in H. axyridis. Recombination between pannier alleles may be reduced by a highly divergent sequence of ∼170 kb in the cis-regulatory regions of pannier, with a 50 kb inversion between color forms. This most likely helps maintain the distinct alleles found in natural populations. Thus, we propose that highly variable discrete color forms can arise in natural populations through cis-regulatory allelic variation of a single gene. More than 200 distinct color forms have been described in natural populations of the harlequin ladybird, Harmonia axyridis. Gautier et al. show that this variation is controlled by the transcription factor Pannier. Pannier is necessary to produce black pigment, and its expression pattern prefigures the coloration pattern in each color form

Gene expression profiling for molecular distinction and characterization of laser captured primary lung cancers

<p>Abstract</p> <p>Methods</p> <p>We examined gene expression profiles of tumor cells from 29 untreated patients with lung cancer (10 adenocarcinomas (AC), 10 squamous cell carcinomas (SCC), and 9 small cell lung cancer (SCLC)) in comparison to 5 samples of normal lung tissue (NT). The European and American methodological quality guidelines for microarray experiments were followed, including the stipulated use of laser capture microdissection for separation and purification of the lung cancer tumor cells from surrounding tissue.</p> <p>Results</p> <p>Based on differentially expressed genes, different lung cancer samples could be distinguished from each other and from normal lung tissue using hierarchical clustering. Comparing AC, SCC and SCLC with NT, we found 205, 335 and 404 genes, respectively, that were at least 2-fold differentially expressed (estimated false discovery rate: < 2.6%). Different lung cancer subtypes had distinct molecular phenotypes, which also reflected their biological characteristics. Differentially expressed genes in human lung tumors which may be of relevance in the respective lung cancer subtypes were corroborated by quantitative real-time PCR.</p> <p>Genetic programming (GP) was performed to construct a classifier for distinguishing between AC, SCC, SCLC, and NT. Forty genes, that could be used to correctly classify the tumor or NT samples, have been identified. In addition, all samples from an independent test set of 13 further tumors (AC or SCC) were also correctly classified.</p> <p>Conclusion</p> <p>The data from this research identified potential candidate genes which could be used as the basis for the development of diagnostic tools and lung tumor type-specific targeted therapies.</p

Etude des effets d'un composé soufré libéré par les Allium, le disulfure de diméthyle, sur les neurones d'insecte et sur l'activité électroencéphalographique de souris

Dimethyl disulfide (DMDS), an Allium-derivative compound, is a promising fumigant as a substitute for methyl bromide. Using patch-clamp, molecular biology and calcium imaging techniques on insect neurones, we identified new targets altered by DMDS at low concentration (1 µM). DMDS transforms regular pacemaker activity of DUM neurones into bursting activities separated by silencing phases. The change in frequency is a consequence of modification of numerous targets. First, we showed that DMDS shifts the voltage dependence of steady-state activation and inactivation of Na2 current toward more negative potentials, which makes cell more excitable. Then, we demonstrate that DMDS induces a calcium rise through TRPg activation and release from intracellular calcium stores. This calcium changes induce a bell-shape modulation of calcium-dependent potassium currents (KCa). Thanks to the study of how of DMDS acts on DUM neurones and development of new techniques associating molecular biology with electrophysiology we support new arguments for existence of two disctint KCa currents. In parallel, thanks to an electroencephalography technique using telemetry on mice, we revealed that DMDS could induce anomalies on electroencephographic activity.Le disulfure de diméthyle (DMDS), molécule volatile libérée par les Allium, est un fumigant prometteur en remplacement du bromure de méthyle. Par l'utilisation des techniques d'électrophysiologie (patch-clamp), de biologie moléculaire et d'imagerie calcique sur neurones d'insectes, nous avons identifié de nouvelles cibles altérées par le DMDS à une faible concentration (1 µM). Le DMDS modifie l'activité spontanée régulière des DUM neurones en des bouffées de potentiels d'action séparées par des phases de silence. Cette altération de fréquence est la conséquence d'effets sur plusieurs cibles. Nous avons montré que le DMDS décale la dépendance vis-à-vis du potentiel de l'activation et de l'inactivation du courant Na2 vers de potentiels plus négatifs, rendant la cellule plus excitable. Dans un deuxième temps nous avons mis en évidence que le DMDS induit une augmentation de la concentration en calcium intracellulaire via l'activation des canaux TRPg et une sortie de calcium des stocks intracellulaires. Cette variation de calcium module, en cloche, les courants potassium dépendants du calcium (KCa). Grâce à l'étude du mode d'action du DMDS sur DUM neurones et au développement de nouvelles techniques associant la biologie moléculaire à l'électrophysiologie, nous avons apporté de nouveaux arguments en faveur de l'existence de deux courants KCa distincts. Parallèlement, grâce à une technique d'électroencéphalographie par télémétrie sur souris, nous avons révélé que le DMDS est susceptible d'engendrer des anomalies de l'activité électroencéphalographique

Physiologie des stomates. Reponse a la lumiere bleue des protoplastes de cellules de garde

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 82616 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Migration and regional identity

Migration is at the centre of human history (Benmayor & Skotnes, 1994, p.5) and it has become easier to migrate inside Europe since the Schengen Area has been implemented in 1995. However, European immigration in France is invisibe and very little researched (Lillo, 2014, p.85). The migration to Brittany is a phenomenom developed recently (Morillon & Etiemble, 2008, p.125) and even if it is gaining momentum, this French region has still the lowest rate of immigrants in France (Economic and Social Council of Brittany, 2007, p.87, INSEE & DRJSCS, 2005, p.5-6). Brittany's regional identity is well known in France (Quand les sondages sont unanimes, 2019, p.44) and this region is defined as one with a strong identity (Kernalegenn, 2011). The aim of this master thesis is to elaborate hypothesis about whether or not European immigrants are aware of Brittany's regional identity before settling in the region, the perception they have of Brittany's regional identity once they live there and finally whether or not their integration in this French region with a strong identity is difficult. This qualitative research is based on four semi-structured interviews with European immigrants and one with a French person born in England, all now living in Brittany

Calcium-Activated Potassium Channels in Insect Pacemaker Neurons as Unexpected Target Site for the Novel Fumigant Dimethyl Disulfide

International audienceDimethyl disulfide (DMDS), a plant-derived insecticide, is a promising fumigant as a substitute for methyl bromide. To further understand the mode of action of DMDS, we examined its effect on cockroach octopaminergic neurosecretory cells, called dorsal unpaired median (DUM) neurons, using whole-cell patch-clamp technique, calcium imaging and antisense oligonucleotide strategy. At low concentration (1 M), DMDS modified spontaneous regular spike discharge into clear bursting activity associated with a decrease of the amplitude of the afterhyperpolarization. This effect led us to suspect alterations of calcium-activated potassium currents (IKCa) and [Ca2]i changes. We showed that DMDS reduced amplitudes of both peak transient and sustained components of the total potassium current. IKCa was confirmed as a target of DMDS by using iberiotoxin, cadmium chloride, and pSlo antisense oligonucleotide. In addition, we showed that DMDS induced [Ca2]i rise in Fura-2-loaded DUM neurons. Using calcium-free solution, and (R,S)-(3,4-dihydro-6,7-dimethoxy-isoquinoline-1-yl)-2-phenyl- N,N-di-[2-(2,3,4-trimethoxy-phenyl)ethyl]-acetamide (LOE 908) [an inhibitor of transient receptor potential (TRP)], we demonstrated that TRP initiated calcium influx. By contrast, ~-conotoxin GVIA (an inhibitor of N-type high-voltage-activated calcium channels), did not affect the DMDS-induced [Ca2]i rise. Finally, the participation of the calcium-induced calcium release mechanism was investigated using thapsigargin, caffeine, and ryanodine. Our study revealed that DMDS-induced elevation in [Ca2]i modulated IKCa in an unexpected bell-shaped manner via intracellular calcium. In conclusion, DMDS affects multiple targets, which could be an effective way to improve pest control efficacy of fumigation

Companion Plants for Aphid Pest Management

A potential strategy for controlling pests is through the use of "companion plants" within a crop system. This strategy has been used in several trials to fight against a major crop insect pest: the aphid. We reviewed the literature to highlight the major mechanisms by which a companion plant may act. Trials carried out under laboratory or field conditions revealed that companion plants operate through several mechanisms. A companion plant may be associated with a target crop for various reasons. Firstly, it can attract aphids and draw them away from their host plants. Secondly, it can alter the recognition of the host plant. This effect is mostly attributed to companion plant volatiles since they disturb the aphid host plant location, and additionally they may react chemically and physiologically with the host plant, making it an unsuitable host for aphids. Thirdly, it can attract natural enemies by providing shelter and food resources. In this review, the feasibility of using companion plants is discussed. We conclude that many factors need to be taken into account for a successful companion plant strategy. For the best long-term results, companion plant strategies have to be combined with other alternative approaches against aphids