Histamine production during the anti-allograft response. Demonstration of a new lymphokine enhancing histamine synthesis

Histamine production is greatly increased during culture of allograft recipient spleen cells in the presence of immunizing cells (secondary mixed leukocyte cultures [MLC]) as compared to that found in primary MLC (i.e., without previous allograft). This phenomenon appears after 24 h of culture and reaches its maximum at 48 h. Optimal increased histamine production is observed when MLC is performed with spleen cells removed from mice during rejection. This increased production of histamine during secondary MLC results from the action of a lymphokine: the histamine-producing cell stimulating factor (HCSF). This factor is released by T lymphocytes. Its production requires specific stimulation of the recipient lymphocytes because increase in histamine production during secondary MLC can be only observed when recipient cells are cultured with stimulating cells bearing at least one homology at K or D loci with immunizing cells. HCSF acts on a cell which is present in bone marrow, spleen, blood, and peritoneal cells but absent in thymus or lymph node cells. This target cell is found in the less-dense layer of a discontinuous Ficoll-gradient of bone marrow cells. HCSF is heat stable, destroyed by trypsin treatment, and has a molecular weight between 50,000 and 100,000. It acts on its target cells by increasing histidine decarboxylase activity

The Receptor-Like Kinase SERK3/BAK1 Is Required for Basal Resistance against the Late Blight Pathogen Phytophthora infestans in Nicotiana benthamiana

BACKGROUND The filamentous oomycete plant pathogen Phytophthora infestans causes late blight, an economically important disease, on members of the nightshade family (Solanaceae), such as the crop plants potato and tomato. The related plant Nicotiana benthamiana is a model system to study plant-pathogen interactions, and the susceptibility of N. benthamiana to Phytophthora species varies from susceptible to resistant. Little is known about the extent to which plant basal immunity, mediated by membrane receptors that recognise conserved pathogen-associated molecular patterns (PAMPs), contributes to P. infestans resistance. PRINCIPAL FINDINGS We found that different species of Phytophthora have varying degrees of virulence on N. benthamiana ranging from avirulence (incompatible interaction) to moderate virulence through to full aggressiveness. The leucine-rich repeat receptor-like kinase (LRR-RLK) BAK1/SERK3 is a major modulator of PAMP-triggered immunity (PTI) in Arabidopsis thaliana and N. benthamiana. We cloned two NbSerk3 homologs, NbSerk3A and NbSerk3B, from N. benthamiana based on sequence similarity to the A. thaliana gene. N. benthamiana plants silenced for NbSerk3 showed markedly enhanced susceptibility to P. infestans infection but were not altered in resistance to Phytophthora mirabilis, a sister species of P. infestans that specializes on a different host plant. Furthermore, silencing of NbSerk3 reduced the cell death response triggered by the INF1, a secreted P. infestans protein with features of PAMPs. CONCLUSIONS/SIGNIFICANCE We demonstrated that N. benthamiana NbSERK3 significantly contributes to resistance to P. infestans and regulates the immune responses triggered by the P. infestans PAMP protein INF1. In the future, the identification of novel surface receptors that associate with NbSERK3A and/or NbSERK3B should lead to the identification of new receptors that mediate recognition of oomycete PAMPs, such as INF1.This work was supported by the Gatsby Charitable Foundation, BBSRC, Nuffield Foundation and the German Research Foundation (DFG). SS was supported by a personal research fellowship (SCHO1347/1-1). JPR is an Australian Research Council Future Fellow (FT0992129). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Stranger in a strange land:the experiences of immigrant researchers

Continuing with our Q&A series discussing issues of diversity in STEM fields, Genome Biology spoke with three researchers on their experiences as immigrants.  International collaborations are key to advancing scientific research globally and often require mobility on the part of researchers. Migration of scientists enables the spread of ideas and skills around the world, giving researchers the opportunity to follow the best resources. Of course, migration adds a new set of challenges to the already monumental task of starting and running a lab. Genome Biology spoke to Sophien Kamoun, Rosa Lozano-Durán, and Luay Nakhleh about their personal experiences

Meeting report:Fungal genomics meets social media: Highlights of the 28th fungal genetics conference at asilomar

International audienc

Diagnostic Based on Estimation Using Linear Programming for Partially Observable Petri Nets with Indistinguishable Events

In this paper, we design a diagnostic technique for a partially observed labelled Petri net where the faults of the system are modelled by unobservable transitions. The fault detection and isolation uses an on-line count vector estimation associated with the firing of unobservable transitions exploiting the observation of firing occurrences of some observable transitions. The support of the approach is an algebraic description of the process under the form of a polyhedron developed on a receding horizon. We show that a diagnostic can be made despite that different transitions can share the same label and that the unobservable part of the Petri net can contain circuits

Diagnosis Using an Estimation Method for Partially Observed Petri Net

International audienc

The Receptor-Like Kinase SERK3/BAK1 Is Required for Basal Resistance against the Late Blight Pathogen Phytophthora infestans in Nicotiana benthamiana

Background: The filamentous oomycete plant pathogen Phytophthora infestans causes late blight, an economically important disease, on members of the nightshade family (Solanaceae), such as the crop plants potato and tomato. The related plant Nicotiana benthamiana is a model system to study plant-pathogen interactions, and the susceptibility of N. benthamiana to Phytophthora species varies from susceptible to resistant. Little is known about the extent to which plant basal immunity, mediated by membrane receptors that recognise conserved pathogen-associated molecular patterns (PAMPs), contributes to P. infestans resistance. Principal findings: We found that different species of Phytophthora have varying degrees of virulence on N. benthamiana ranging from avirulence (incompatible interaction) to moderate virulence through to full aggressiveness. The leucine-rich repeat receptor-like kinase (LRR-RLK) BAK1/SERK3 is a major modulator of PAMP-triggered immunity (PTI) in Arabidopsis thaliana and N. benthamiana. We cloned two NbSerk3 homologs, NbSerk3A and NbSerk3B, from N. benthamiana based on sequence similarity to the A. thaliana gene. N. benthamiana plants silenced for NbSerk3 showed markedly enhanced susceptibility to P. infestans infection but were not altered in resistance to Phytophthora mirabilis, a sister species of P. infestans that specializes on a different host plant. Furthermore, silencing of NbSerk3 reduced the cell death response triggered by the INF1, a secreted P. infestans protein with features of PAMPs. Conclusions/significance: We demonstrated that N. benthamiana NbSERK3 significantly contributes to resistance to P. infestans and regulates the immune responses triggered by the P. infestans PAMP protein INF1. In the future, the identification of novel surface receptors that associate with NbSERK3A and/or NbSERK3B should lead to the identification of new receptors that mediate recognition of oomycete PAMPs, such as INF1

NLR receptors in plant immunity: Making sense of the alphabet soup

Plants coordinately use cell-surface and intracellular immune receptors to perceive pathogens and mount an immune response. Intracellular events of pathogen recognition are largely mediated by immune receptors of the nucleotide binding and leucine rich-repeat (NLR) classes. Upon pathogen perception, NLRs trigger a potent broad-spectrum immune reaction, usually accompanied by a form of programmed cell death termed the hypersensitive response. Some plant NLRs act as multifunctional singleton receptors which combine pathogen detection and immune signaling. However, NLRs can also function in higher order pairs and networks of functionally specialized interconnected receptors. In this article, we cover the basic aspects of plant NLR biology with an emphasis on NLR networks. We highlight some of the recent advances in NLR structure, function, and activation and discuss emerging topics such as modulator NLRs, pathogen suppression of NLRs, and NLR bioengineering. Multi-disciplinary approaches are required to disentangle how these NLR immune receptor pairs and networks function and evolve. Answering these questions holds the potential to deepen our understanding of the plant immune system and unlock a new era of disease resistance breeding

Analogies de méthodes et différences d'appareillage dans l'enregistrement d'informations corrélées

L'enregistrement des énergies de particules corrélées : expériences (α, γ), (3He, dγ), (d, pγ), (p, p' γ), expériences de polarisation [4, 6,12], a été effectué indépendamment avec des appareillages de conceptions différentes. L'un est un système d'acquisition et de contrôle utilisant une logique câblée, l'autre un ordinateur en temps réel. L'examen critique de ces appareillages et de leur utilisation conduit à des conclusions voisines

The nucleotide-binding domain of NRC-dependent disease resistance proteins is sufficient to activate downstream helper NLR oligomerization and immune signaling

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins with pathogen sensor activities have evolved to initiate immune signaling by activating helper NLRs. However, the mechanisms underpinning helper NLR activation by sensor NLRs remain poorly understood. Although coiled coil (CC) type sensor NLRs such as the Potato virus X disease resistance protein Rx have been shown to activate the oligomerization of their downstream helpers NRC2, NRC3 and NRC4, the domains involved in sensor–helper signaling are not known. Here, we used Agrobacterium tumefaciens-mediated transient expression in Nicotiana benthamiana to show that the nucleotide-binding (NB) domain within the NB-ARC of Rx is necessary and sufficient for oligomerization and immune signaling of downstream helper NLRs. In addition, the NB domains of the disease resistance proteins Gpa2 (cyst nematode resistance), Rpi-amr1, Rpi-amr3 (oomycete resistance) and Sw-5b (virus resistance) are also sufficient to activate their respective downstream NRC helpers. Using transient expression in the lettuce (Lactuca sativa), we show that Rx (both as full length or as NB domain truncation) and its helper NRC2 form a minimal functional unit that can be transferred from solanaceous plants (lamiids) to Campanulid species. Our results challenge the prevailing paradigm that NLR proteins exclusively signal via their N-terminal domains and reveal a signaling activity for the NB domain of NRC-dependent sensor NLRs. We propose a model in which helper NLRs can perceive the status of the NB domain of their upstream sensors