Identification of Tea Storage Times by Linear Discrimination Analysis and Back-Propagation Neural Network Techniques Based on the Eigenvalues of Principal Components Analysis of E-Nose Sensor Signals

An electronic nose (E-nose) was employed to detect the aroma of green tea after different storage times. Longjing green tea dry leaves, beverages and residues were detected with an E-nose, respectively. In order to decrease the data dimensionality and optimize the feature vector, the E-nose sensor response data were analyzed by principal components analysis (PCA) and the five main principal components values were extracted as the input for the discrimination analysis. The storage time (0, 60, 120, 180 and 240 days) was better discriminated by linear discrimination analysis (LDA) and was predicted by the back-propagation neural network (BPNN) method. The results showed that the discrimination and testing results based on the tea leaves were better than those based on tea beverages and tea residues. The mean errors of the tea leaf data were 9, 2.73, 3.93, 6.33 and 6.8 days, respectively

Effects of mti-2

Overexpressed in transgenic plants, protease inhibitors showed insecticidal effects against several insect taxa. We transformed potato internodes with the mustard trypsin inhibitor mti-2 gene. Among the 35 independent transgenic potato lines obtained via Agrobacterium tumefasciens transformation, four (DM6, DM7, DM11, and DM19) were selected for their high level of MTI-2 (at least to 30% of trypsin activity inhibition). Feeding assays were carried out to evaluate their effects on the green-peach aphid, Myzus persicae (Sternorrhyncha: Aphididae). Prereproductive period, nymphal mortality, adult fecundity, and doubling time of M. persicae populations were monitored on nontransformed potato plants (NT) and the four selected DM lines. Compared to NT plants, DM19 did not induce any effect on M. persicae. In contrast, DM7 and DM11 increased nymphal survival by approximately 20%. DM6 and DM11 lines slightly enhanced M. persicae daily fecundity and intrinsic rate of natural increase, leading to a reduction of the doubling time of the populations by 1 day. DM6 did not impact nymphal mortality, whereas with the DM11 almost all the nymphs survived. Potato plants transformed with the mti-2 gene variably affected the life history of M. persicae but did not show any insecticidal effect on the aphid

Singer, Fred D.— Ecology in action. Cambridge University Press, Cambridge & New York, 2016

Laberche J.C. Singer, Fred D.— Ecology in action. Cambridge University Press, Cambridge & New York, 2016. In: Revue d'Écologie (La Terre et La Vie), tome 73, n°2, 2018. pp. 209-210

Les irrigations sous abri.

National audienc

Approches des facteurs de la croissance et du développement de Salicornia Ramosissima Woods en conditions naturelles et contrôlées

En vue d une domestication, Salicornia ramosissima poussant spontanément et déjà grandement récoltée en Baie de Somme, à fait l objet d études présentées dans cette thèse. Après une revue bibliographique permettant de préciser les connaissances déjà acquises sur les salicornes en général et Salicornia ramosissima en particulier, la partie expérimentale porte essentiellement sur l étude des facteurs abiotiques agissant sur la floraison, la maturation et la dormance des graines, ainsi que sur la germination. Il en est de même pour les phénomènes de croissance et de développement. Les travaux ont été complétés quand il était nécessaire par des études anatomiques ou cytologiques, voire métaboliques. Les résultats obtenus permettent d envisager favorablement un transfert de technologie pour cette plante.In the Bay of Somme, Salicornia ramosissima grows up spontaneously and already is largely collected. The species is the subject of the studies presented in this thesis. The first part (bibliography) describes the knowledges published on the salicornes and Salicornia ramosissima. After, are presented the abiotic factors acting on the flowering, the maturation and the dormancy of seeds, like on germination. It is the same for the phenomena of growth and development. Experiments are supplemented when it is necessary by anatomical, or cytological even metabolic studies. The results prepare a technology transfer for this plant.AMIENS-BU Sciences (800212103) / SudocSudocFranceF

Dérégulation des activités chitinases (vers de nouvelles perspectives de lutte contre les aphides)

Chez les insectes, les chitinases sont des enzymes principalement impliquées dans la dégradation de la chitine, lors des processus de croissance. Les chitinases représentent donc des cibles d intérêt dans le développement de moyens de lutte alternatifs aux pesticides utilisés contre les ravageurs des cultures. Au cours de ces travaux de thèse, nous avons été amené à évaluer la pertinence de la dérégulation des activités chitinases chez les pucerons. L impact des chitinases sur le développement du puceron M. persicae a été évalué par des tests de prise alimentaire réalisés in planta, sur des plantes de pommes de terre exprimant une chitinase d insecte (Phaedon cochleariae, Coléoptère) et in vitro, en incorporant une chitinase bactérienne (Serratia marcescens) dans un milieu artificiel. Des effets probiotiques ont été mis en évidence dans les deux cas, remettant en cause l utilisation des chitinases en tant que biopesticide pour lutter contre les pucerons.Compte tenu de ces effets inattendus, nous avons étudié les effets d une stratégie antagoniste, basée sur l utilisation d inhibiteurs de chitinases. Quatre inhibiteurs de chitinases, d origine et de nature variées, ont ainsi été testés via un milieu artificiel. Nos résultats rapportent pour la première fois une activité inhibitrice de ces molécules sur des pucerons. Nous avons donc orienté nos recherches dans cette voie, afin d identifier de nouveaux inhibiteurs de chitinases. Deux approches ont été initiées avec d une part la purification des chitinases du puceron M. persicae et d autre part par l évaluation des effets d oligosaccharides mimétiques de la chitine et des inhibiteurs de chitinases. Les résultats obtenus nous laissent à penser que les inhibiteurs de chitinases constituent une voie prometteuse dans l élaboration de nouveaux bioinsecticides.In insects, chitinases are key enzymes in chitin degradation, and especially during molting and growth process. As a consequence, chitinase metabolism in an interesting targets to develop new alternatives method to manage insect pests. In this project, we evaluated the relevance of the disturbance of aphid chitinase activities. The impact of chitinases was evaluated on M. persicae development via in planta tests, rearing aphids on potato plants expressing an insect chitinase (Phaedon cochleariae, Coleoptera) and via in vitro tests, via an artificial diet containing a bacterial chitinase (Serratia marcescens). Probiotic effects were described in both cases and our results, question us on the reliability of the use of chitinases as biopesticides to fight aphids. We evaluated the effects of an antagonist strategy based on chitinase inhibitors. Four of them, from different origins were tested via an artificial diet. Our results reported for the first time the inhibitory activity of chitinase inhibitors on aphids. We focused our searches in this way with the aim to identify new chitinases inhibitors. In a first approach, we initiated the purification of M. persicae chitinases and in a second one, we evaluated the effects of oligossacharides which mimic chitin and chitinase inhibitors. Our results highlight the potential use of chitinase inhibitors as new bioinsecticides in pest management programs.AMIENS-BU Sciences (800212103) / SudocSudocFranceF

Occurrence of circadian rhythms in hairy root cultures grown under controlled conditions

Hairy roots obtained by transformation via Agrobacterium rhizogenes provide an artificial plant material devoid of aerial parts with high growth on hormone-free media. Fundamental knowledge of hairy root physiology is essential to develop and control its culture. In contrast to shake-flask cultures, a bioreactor set-up combined with on-line data logging provides an efficient tool to study rapid physiological variations in hairy root cultures. Datura innoxia hairy roots were grown in a bioreactor equipped with on-line data analyses of pH, dissolved oxygen (pO2), conductivity, oxygen, and carbon dioxide. The experiments were done at a constant temperature and in the absence of light cues. The results obtained showed that the carbon dioxide evolution rate (CER) presented regular oscillations during the culture. Similar oscillations were also observed for the oxygen uptake rate (OUR). These signals were treated mathematically to look for the existence of a rhythm. An autocorrelation function was used to detect any periodic components. The results demonstrate that hairy root respiration exhibited peaks of 1 day. These oscillations, having a period of about 24 h, were also observed in pH and conductivity signals, although not for the pO2 signal. The data acquired in the absence of hairy roots showed that the observed periodic behavior was not an artifact. No effect on rhythms was observed by the imposition of an external "day/night" cycle. The fact that oscillations persisted in the absence of external stimuli, with a free-running period of 24 h, suggests that a circadian rhythm exists in hairy roots of D. innoxia

Exopolysaccharide production by nitrogen-fixing bacteria within nodules of Medicago plants exposed to chronic radiation in the Chernobyl exclusion zone

International audienceNitrogen-fixing bacteria isolated from root nodules of Medicago plants growing in the 10 km zone around the Chernobyl nuclear power plant were screened for the production of new water-soluble acidic exopolysaccharides (EPSs). The different strains belonged to the Enteriobacteriaceae family (Enterobacter ludwigii, Raoultella terrigena, Klebsiella oxytoca), except for one which belonged to the Rhizobiaceae family (Sinorhizobium meliloti). All of the bacteria produced highly viscous EPS with an average molecular weight comprised between 1 × 106 and 3 × 106 Da. Five different compositions of EPS were characterized by physico-chemical analyses and 1H NMR spectroscopy: galactose/mannose (2/1), galactose/glucose (1/1), galactose/glucose/mannose (1/2/1), fucose/galactose/glucose (2/1/1) and fucose/galactose/glucose/mannose (2/2/1/1 or 1/1/2/4). Glucuronic acid, a charged monosaccharide, was also recovered in most of the different EPSs