Инфекционная составляющая и иммунопатология при хронических воспалительных заболеваниях слизистой оболочки гастродуоденальной области

Выявлено коинфицирование слизистой оболочки желудочно−кишечного тракта Helicobacter pylori и вирусами группы герпеса у больных хроническим гастритом, язвенной болезнью желудка и двенадцатиперстной кишки. Проведена оценка общих и специфических иммунных реакций организма на указанные инфекционные агенты. Обнаруженные изменения в клеточном и гуморальном звене иммунитета могут свидетельствовать об обусловленном ими системном иммунопатологическом процессе.Co−infection of the gastrointestinal mucosa with Helicobacter pylori and herpes viruses in patients with chronic gastritis, gastric and duodenal ulcer was revealed. General and specific immune reactions of the organism to the above agents were evaluated. The revealed changes in the cellular and humoral immunity can suggest systemic immunopathological process

Genotypic variability enhances the reproducibility of an ecological study

Many scientific disciplines are currently experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that a deliberate introduction of controlled systematic variability (CSV) in experimental designs may lead to increased reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories across Europe. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility was generally lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the “reproducibility crisis”, deliberately including genetic variation may be a simple solution for increasing the reproducibility of ecological studies performed in controlled environments

Effet du ver de terre Aporrectodea caliginosa sur la croissance des plantes, leur développement et leur résistance aux pathogènes : réponse physiologique et moléculaire de la plante à l'émission de molécules-signal

Plants develop and evolve in interaction with soil organisms. The impact of earthworms, likely positive, has been attributed to modifications of physical, chemical or biochemical soil properties, without rigorous demonstration. In this work, techniques developed in plant science (in vitro culture, use of mutant plants and trancriptomic analysis) were used to understand the mechanism involved in the effect of earthworms on plants. Our results bring new fundamental knowledge: (1) production of signal-molecules within earthworm dejections has a positive impact on the growth of Oryza sativa and Lolium perenne. (2) These molecules act on auxin signaling, as suggested by the positive impact of the earthworm on the growth of A. thaliana double mutant aux1-7;axr4-2. (3) The abundance of these signal-molecules in presence of the earthworms could be related to the stimulation of bacterial communities able to produce auxin. (4) Earthworms induce an accumulation of gene transcripts known to be under control of jasmonic acid and ethylene. These two hormones are most notably involved in the defense mechanism called induced systemic resistance (ISR), known to be induced by plant growth promoting rhizobacteria. Finally, (5) Take-all disease, due to a pathogenic fungus, induced in wheat (Triticum aestivum) a hypersensitive response and a modification on hormone signaling, which are known as manipulations of plant metabolism in a way that facilitates pathogen infection. The severity of take-all disease was alleviated in the presence of earthworms. Synthesis of these results showed that earthworms, like other soil organisms, modify the hormone balance in the plant. Hormone homeostasis appeared to be an important element to predict the issue of the multiple interactions that plants established with soil organismsLes plantes se développent et évoluent en interaction avec les organismes du sol. L'impact des vers de terre sur la croissance des plantes, généralement positif, a été attribué à des modifications physiques, chimiques ou biochimiques du sol, souvent sans démonstration rigoureuse. Dans ce travail, les techniques développées en sciences du végétal (culture in vitro, utilisation de mutants et transcriptomique) ont été utilisées afin de comprendre les mécanismes à l'origine de l'effet des vers de terre sur les plantes. Nos résultats apportent de nouvelles connaissances fondamentales: (1) la production de molécules-signal à l'intérieur des déjections de vers de terre a un impact significatif sur la croissance d'Oryza sativa et Lolium perenne. (2) Ces molécules agissent sur la voie de signalisation fortement liée à l'auxine, comme suggéré par l'effet significatif du ver de terre sur la croissance du double mutant d'A. thaliana aux1-7;axr4-2. (3) L'abondance de ces molécules-signal en présence de vers de terre pourrait être liée à la stimulation de certaines populations bactériennes capables de synthétiser de l'auxine. (4) Le ver de terre induit une accumulation de transcrits pour des gènes sous contrôle de l'acide jasmonique et de l'éthylène. Ces hormones sont notamment impliquées dans un mécanisme de résistance systémique induite (ISR), connu pour être induit par certaines rhizobactéries promotrices de la croissance des plantes. Enfin, (5) le piétin échaudage, maladie due à un champignon pathogène, déclenche chez le blé (Triticum aestivum) une réaction d'hypersensibilité et une modification de la signalisation hormonale, qui sont considérées comme des mécanismes de contrôle du métabolisme de la plante qui facilitent l'infection du pathogène. La sévérité de cette maladie est réduite en présence de vers de terre. La synthèse de ces résultats indique que les vers de terre, comme d'autres organismes du sol, modifient l'équilibre hormonal de la plante. L'homéostasie hormonale apparaît comme un élément incontournable pour prédire l'issue des interactions multiples que les plantes entretiennent avec les organismes du so

Impact of the earthworm Aporrectodea caliginosa on plant growth, development and resistance against pathogens : physiological and molecular plant response to the emission of signal molecules

Plants develop and evolve in interaction with soil organisms. The impact of earthworms, likely positive, has been attributed to modifications of physical, chemical or biochemical soil properties, without rigorous demonstration. In this work, techniques developed in plant science (in vitro culture, use of mutant plants and trancriptomic analysis) were used to understand the mechanism involved in the effect of earthworms on plants. Our results bring new fundamental knowledge: (1) production of signal-molecules within earthworm dejections has a positive impact on the growth of Oryza sativa and Lolium perenne. (2) These molecules act on auxin signaling, as suggested by the positive impact of the earthworm on the growth of A. thaliana double mutant aux1-7;axr4-2. (3) The abundance of these signal-molecules in presence of the earthworms could be related to the stimulation of bacterial communities able to produce auxin. (4) Earthworms induce an accumulation of gene transcripts known to be under control of jasmonic acid and ethylene. These two hormones are most notably involved in the defense mechanism called induced systemic resistance (ISR), known to be induced by plant growth promoting rhizobacteria. Finally, (5) Take-all disease, due to a pathogenic fungus, induced in wheat (Triticum aestivum) a hypersensitive response and a modification on hormone signaling, which are known as manipulations of plant metabolism in a way that facilitates pathogen infection. The severity of take-all disease was alleviated in the presence of earthworms. Synthesis of these results showed that earthworms, like other soil organisms, modify the hormone balance in the plant. Hormone homeostasis appeared to be an important element to predict the issue of the multiple interactions that plants established with soil organismsLes plantes se développent et évoluent en interaction avec les organismes du sol. L'impact des vers de terre sur la croissance des plantes, généralement positif, a été attribué à des modifications physiques, chimiques ou biochimiques du sol, souvent sans démonstration rigoureuse. Dans ce travail, les techniques développées en sciences du végétal (culture in vitro, utilisation de mutants et transcriptomique) ont été utilisées afin de comprendre les mécanismes à l'origine de l'effet des vers de terre sur les plantes. Nos résultats apportent de nouvelles connaissances fondamentales: (1) la production de molécules-signal à l'intérieur des déjections de vers de terre a un impact significatif sur la croissance d'Oryza sativa et Lolium perenne. (2) Ces molécules agissent sur la voie de signalisation fortement liée à l'auxine, comme suggéré par l'effet significatif du ver de terre sur la croissance du double mutant d'A. thaliana aux1-7;axr4-2. (3) L'abondance de ces molécules-signal en présence de vers de terre pourrait être liée à la stimulation de certaines populations bactériennes capables de synthétiser de l'auxine. (4) Le ver de terre induit une accumulation de transcrits pour des gènes sous contrôle de l'acide jasmonique et de l'éthylène. Ces hormones sont notamment impliquées dans un mécanisme de résistance systémique induite (ISR), connu pour être induit par certaines rhizobactéries promotrices de la croissance des plantes. Enfin, (5) le piétin échaudage, maladie due à un champignon pathogène, déclenche chez le blé (Triticum aestivum) une réaction d'hypersensibilité et une modification de la signalisation hormonale, qui sont considérées comme des mécanismes de contrôle du métabolisme de la plante qui facilitent l'infection du pathogène. La sévérité de cette maladie est réduite en présence de vers de terre. La synthèse de ces résultats indique que les vers de terre, comme d'autres organismes du sol, modifient l'équilibre hormonal de la plante. L'homéostasie hormonale apparaît comme un élément incontournable pour prédire l'issue des interactions multiples que les plantes entretiennent avec les organismes du so

A review of the effects of soil organisms on plant hormone signalling pathways

International audiencePlants interact with a large number of soil organisms. For a long time, these interactions have been the research area of soil ecologists and trophic relationships and physico-chemical modifications of the soil matrix were generally proposed as mechanisms underlying plant-soil organism interactions. However, some specific symbioses and diseases have been well characterized at the molecular level by plant biologists and microbiologists. These interactions involve a physical contact between soil organism and plant. They are mediated through signal molecules that play upon the different plant hormonal signalling pathways, leading to modifications in plant development and defence. Nowadays, the role of signal molecules emerges as an important feature of interactions between plants and free-living soil organisms. In this review we discuss genetic and physiological evidences of hormone signalling involvement in plant response to physically associated but also free-living soil organisms, for very different taxa ranging from the micrometer to the centimetre scales. The same hormone signalling pathways seems to be activated by very different kinds of soil organisms such as bacteria, nematodes, collembola and even earthworms, with common consequences on plant growth, development and defence. Plant hormonal homeostasis appears to be the corner stone to understand and predict the issue of the multiple interactions that plants entertain with the community of soil organisms

How soil organisms interact with plant hormone signaling pathways

National audiencePlants interact with a large number of soil organisms. For a long time, these interactions have been the research area of soil ecologists and trophic relationships and physico-chemical modifications of the soil matrix were generally proposed as mechanisms underlying plant-soil organism interactions. However, some specific symbioses and diseases have been well characterized at the molecular level by plant biologists and microbiologists. These interactions involve a physical contact between soil organism and plant. They are mediated through signal molecules that play upon the different plant hormonal signalling pathways, leading to modifications in plant development and defence. Nowadays, the role of signal molecules emerges as an important feature of interactions between plants and free-living soil organisms. In this work we discuss genetic and physiological evidences of hormone signalling involvement in plant response to physically associated but also free-living soil organisms, for very different taxa ranging from the micrometer to the centimetre scales. The same hormone signalling pathways seems to be activated by very different kinds of soil organisms such as bacteria, nematodes, collembola and even earthworms, with common consequences on plant growth, development and defence. Plant hormonal homeostasis appears to be the corner stone to understand and predict the issue of the multiple interactions that plants entertain with the community of soil organisms

How soil organisms interact with plant hormone signaling pathways

National audiencePlants interact with a large number of soil organisms. For a long time, these interactions have been the research area of soil ecologists and trophic relationships and physico-chemical modifications of the soil matrix were generally proposed as mechanisms underlying plant-soil organism interactions. However, some specific symbioses and diseases have been well characterized at the molecular level by plant biologists and microbiologists. These interactions involve a physical contact between soil organism and plant. They are mediated through signal molecules that play upon the different plant hormonal signalling pathways, leading to modifications in plant development and defence. Nowadays, the role of signal molecules emerges as an important feature of interactions between plants and free-living soil organisms. In this work we discuss genetic and physiological evidences of hormone signalling involvement in plant response to physically associated but also free-living soil organisms, for very different taxa ranging from the micrometer to the centimetre scales. The same hormone signalling pathways seems to be activated by very different kinds of soil organisms such as bacteria, nematodes, collembola and even earthworms, with common consequences on plant growth, development and defence. Plant hormonal homeostasis appears to be the corner stone to understand and predict the issue of the multiple interactions that plants entertain with the community of soil organisms

Earthworm effect on rhizosphere N-cycle microbial genes depends on soil properties

International audienceEarthworms are known to improve plant growth in a soil-dependent way, notably via modifications of the rhizosphere microbiota and its functions. We tested the hypothesis that earthworms influence the abundance of microbial genes involved in N cycle according to the type of soil. In three soils with contrasting texture, we quantified five N-cycling genes in different microsites (bulk, rhizosphere or earthworm casts) of microcosms containing (i) neither plants nor eathworms, (ii) plants, (iii) earthworms, (iv) both plant and earthworms. In the presence of earthworms, rhizophere was enriched in nifH (N2 fixation) and depressed in nosZ or narG (denitrification) in sandy soil, suggesting a shift in N balance towards immobilization; rhizosphere was enriched in nifH but also nosZ and narG in loamy soil; no effect was detected in clayey soil. The pattern of gene abundance across the different soils and microsites suggests that earthworms could favor microorganisms with a potential beneficial effect on plants specifically in sandy soils

Plant-earthworm interactions : influence of age and proportion of casts in the soil on plant growth, morphology and nitrogen uptake

International audienceEarthworms effect on plant growth is mediated by their dejections or “casts”, a complex mixture of organic matter, minerals and microbes. In casts, different processes such as organic matter mineralization and signal molecule production follow a complex temporal dynamics. An adaptation of root morphology to cast dynamics could allow an efficient nitrogen capture by the plant. The plant Brachypodium distachyon was grown in a laboratory experiment with different proportions of casts of increasing ages. Casts were labelled with 15N to quantify the plant N uptake from the casts. Plant biomass and morphology, especially root system structure, were analysed. The age of casts had an effect on fine root length, highlighting the importance of the dynamics of cast maturation in root adaptation. Plant biomass production was affected by the interaction between the age and proportion of casts. A positive correlation between the 15N proportion in plant tissues and plant biomasses indicated that plants were more efficient in foraging N in casts than in the bulk soil. Our results suggested that both a timely adaptation of the root system structure and a significant proportion of casts are necessary to observe a positive effect of casts on plant growth