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Plant immunity relies on the perception of microbe-associated molecular patterns (MAMPs) from invading microbes to induce defense responses that suppress attempted infections. It has been proposed that MAMP-triggered immunity (MTI) suppresses bacterial infections by suppressing the onset of bacterial virulence. However, the mechanisms by which plants exert this action are poorly understood. Here, we showed that MAMP perception in Arabidopsis (Arabidopsis thaliana) induces the accumulation of free amino acids in a salicylic acid (SA)-dependent manner. When co-infiltrated with Glutamine and Serine, two of the MAMP-induced highly accumulating amino acids, Pseudomonas syringae pv. tomato DC3000 expressed low levels of virulence genes and failed to produce robust infections in otherwise susceptible plants. When applied exogenously, Glutamine and Serine directly suppressed bacterial virulence and growth, bypassing MAMP perception and SA signaling. In addition, an increased level of endogenous Glutamine in the leaf apoplast of a gain-of-function mutant of Glutamine Dumper-1 rescued the partially compromised bacterial virulence- and growth-suppressing phenotype of the SA-induced deficient-2 (sid2) mutant. Our data suggest that MTI suppresses bacterial infections by delaying the onset of virulence with an excess of amino acids at the early stages of infection.

Plants live under the constant challenge of microbes that probe the environment in search of potential hosts. Plant cells perceive microbe-associated molecular patterns (MAMPs) from incoming microbes and activate defense responses that suppress attempted infections. Despite the substantial progress made in understanding MAMP-triggered signaling pathways, the downstream mechanisms that suppress bacterial growth and disease remain poorly understood. Here, we uncover how MAMP perception in Arabidopsis (Arabidopsis thaliana) elicits dynamic changes in extracellular concentrations of free L-amino acids (AA). Within the first 3 h of MAMP perception, a fast and transient inhibition of AA uptake produces a transient increase in extracellular AA concentrations. Within 4 and 12 h of MAMP perception, a sustained enhanced uptake activity decreases the extracellular concentrations of AA. Gene expression analysis showed that salicylic acid-mediated signaling contributes to inducing the expression of AA/H+ symporters responsible for the MAMP-induced enhanced uptake. A screening of loss-of-function mutants identified the AA/H+ symporter lysin/histidine transporter-1 as an important contributor to MAMP-induced enhanced uptake of AA. Infection assays in lht1-1 seedlings revealed that high concentrations of extracellular AA promote bacterial growth in the absence of induced defense elicitation but contribute to suppressing bacterial growth upon MAMP perception. Overall, the data presented in this study reveal a mechanistic connection between MAMP-induced plant defense and suppression of bacterial growth through the modulation of AA transport activity.

Leaf mesophyll-colonizing bacterial pathogens infect their plant hosts by adjusting their metabolism to the leaf mesophyll environment. Soon after the inoculation of naïve, susceptible plants, the model bacterial pathogenPseudomonas syringaepv.tomatoDC3000 (PstDC3000) expresses virulence factors that suppress plant immunity, a requirement to produce robust infections. However, if plant immunity was elicited with Microbe-Associated Molecular-Patterns (MAMPs) prior to bacterial inoculation,PstDC3000 slows down virulence expression and only produces symptomless mild infections. To understand how bacterial metabolism adapts to these two contrasting conditions, we created iPst19, anin silicoensemble of genome-scale metabolic reconstructions. Constraining thein silicogrowth of iPst19 within planta PstDC3000 gene expression data revealed that sugar catabolism is highly active in bacteria that have been inoculated in mock-treated plants. In contrast, branched-chain amino acids (BCAAs) catabolism is highly active in bacteria that have been inoculated in MAMP-pretreated plants. Bacterial growth and gene expression analysis showed that BCAAs suppress virulence gene expression without affecting bacterial growthin vitro. In planta, however, BCAAs suppress the expression of virulence genes at the early stages of the infection and significantly impair leaf colonization of the host plantArabidopsis thaliana. While the overexpression of the conserved bacterial leucine-responsive transcriptional regulatorLrpinduced the expression of virulence genes, its downregulation had the opposite effect, suggesting that BCAA-free Lrp induces virulence while BCAA-Lrpdoes not. Overall, our data provide mechanistic connections to understand how plant immunity impactsPstDC3000 metabolism and virulence, furthering our understanding of bacterial pathogenesis and plant disease.

Plant immunity relies on the perception of Microbe-Associate Molecular Patterns (MAMPs) from invading microbes to induce defense responses that suppress attempted infections. It has been proposed that MAMP-triggered immunity (MTI) suppresses bacterial infections by suppressing the onset of bacterial virulence. However, the mechanisms by which plants exert this action are poorly understood. Here we uncover that MAMP-perception in Arabidopsis induces the accumulation of free amino acids (AA) in a salicylic acid (SA) dependent manner. When co-infiltrated with Glutamine and Serine, two of the MAMP-induced highly accumulating amino acids, Pseudomonas syringae pv. tomato DC3000 expressed low levels of virulence genes and failed to produce robust infections in otherwise susceptible plants. When applied exogenously, Glutamine and Serine suppressed bacterial virulence and bacterial growth directly without the need for MAMP-perception and SA-signaling, bypassing MAMP-elicited defense. In addition, an increased level of endogenous Glutamine in the leaf apoplast of a gain-of-function mutant of Glutamine Dumper-1 rescued the partially compromised bacterial virulence and growth suppressing phenotype of the SA-induced deficient-2 (sid2) mutant. Our data suggest that MTI suppresses bacterial infections by the direct suppressing effect of accumulating amino acids on the onset of bacterial virulence.

The importance of antiviral CD8+ T cell recognition of alternative reading frame (ARF)–derived peptides is uncertain. In this study, we describe an epitope (NS1-ARF21–8) present in a predicted 14-residue peptide encoded by the +1 register of NS1 mRNA in the influenza A virus (IAV). NS1-ARF21–8 elicits a robust, highly functional CD8+ T cell response in IAV-infected BALB/c mice. NS1-ARF21–8 is presented from unspliced NS mRNA, likely from downstream initiation on a Met residue that comprises the P1 position of NS1-ARF21–8. Derived from a 14-residue peptide with no apparent biological function and negligible impacts on IAV infection, infectivity, and pathogenicity, NS1-ARF21–8 provides a clear demonstration of how immunosurveillance exploits natural errors in protein translation to provide antiviral immunity. We further show that IAV infection enhances a model cellular ARF translation, which potentially has important implications for virus-induced autoimmunity.

Les chercheurs etudiant la fecondite chinoise se trouvent dans une situation etrange depuis le debut des annees 1990. Alors que les nombreux recensements, enquetes de fecondite et enquetes demographiques annuelles fournissent suffisamment de donnees pour permettre des travaux approfondis sur la baisse recente de la fecondite, le sous-enregistrement et les incoherences dont souffrent de plus en plus les principales donnees font obstacle a de telles recherches. Ces difficultes sont aussi dues au fait que, si l’administration statistique publie quelques indices de fecondite corriges, elle ne donne pas de details sur les techniques utilisees depuis la fin des annees 1990 pour effectuer ces ajustements. Cet article a pour objectif de combler certains manques de connaissances sur l’evolution recente de la fecondite chinoise, en analysant les incoherences des statistiques de fecondite provenant de sources differentes, puis en reconstituant deux series coherentes d’indicateurs a partir des nombres de naissances officiels publies et de ceux corriges par les auteurs. Ces calculs permettent d’examiner le declin recent de la fecondite chinoise et de montrer que, meme si les problemes de qualite des donnees sont nombreuses, le sous-enregistrement de certaines donnees de fecondite n’est peut-etre pas aussi important que le suggerent les taux bruts de natalite et indicateurs de fecondite corriges officiels. La forte baisse de la fecondite chinoise a commence au debut des annees 1990. L’ISF, au lieu de stagner a 1,8 enfant par femme (chiffre officiel), est tombe au-dessous de 1,7 a la fin de la decennie, et continue de diminuer depuis.

Multiple-Input Multiple-Output (MIMO) systems are capable of simultaneously capturing more than one packet. Such capability is known as Multi-Packet Reception (MPR), which is new way to improve performance of Ad Hoc Networks. In order to effectively enhance throughput of Ad Hoc Networks, a novel MAC protocol (MIMO-MAC) with MIMO links that takes into account MPR is proposed. It can receive more than one RTS before responding CTS, which maximizes transmission links simultaneously. Receiver determines links according to the number of its own antennas and RTS. Compare to the existing protocol, it allows many communications at the same time in one competitive area. Finally, simulations are implemented in terms of load and source nodes number in OPNET environment, results show that MIMO-MAC outperforms CSMA/CA and CSMA/CA (k).

The study of China's fertility has been in a strange situation since the early 1990s. On the one hand, the growing number of censuses, fertility surveys and annual surveys of population change should provide sufficient data for detailed investigation of recent fertility decline; on the other hand, key fertility data are increasingly affected by problems of under-reporting and internal inconsistency that form an obstacle to such investigations. This is partly due to the fact that while the statistical authority has published some adjusted fertility statistics, it has been rather reluctant to release details of the technique used to make such adjustments since the late 1990s. This study intends to fill some gaps in our understanding of China's recent fertility changes. It further investigates the inconsistencies in fertility data obtained from various sources, then reconstructs two sets of internally consistent fertility statistics using officially released numbers of births and our revised numbers of births. On the basis of these reconstructed statistics, the paper examines China's recent fertility decline and addresses a number of related issues. It concludes that while data quality has become a widespread problem, under-reporting of some fertility data may not be as severe as that implied by the officially adjusted CBRs or TFRs. A drastic fertility reduction occurred in China in the early 1990s. The TFR, rather than staying at 1.8 as suggested by the government, fell to below 1.7 in the second half of the decade and has further declined to a lower level since then. Abstract: Les chercheurs etudiant la fecondite chinoise se trouvent dans une situation etrange depuis le debut des annees 1990. Alors que les nombreux recensements, enquetes de fecondite et enquetes demographiques annuelles fournissent suffisamment de donnees pour permettre des travaux approfondis sur la baisse recente de la fecondite, le sous-enregistrement et les incoherences dont souffrent de plus en plus les principales donnees font obstacle a de telles recherches. Ces difficultes sont aussi dues au fait que, si l'administration statistique publie quelques indices de fecondite corriges, elle ne donne pas de details sur les techniques utilisees depuis la fin des annees 1990 pour effectuer ces ajustements. Cette recherche a pour objectif de combler certains manques de connaissances sur l'evolution recente de la fecondite chinoise, en analysant les incoherences des statistiques de fecondite provenant de sources differentes, puis en reconstituant deux series coherentes d'indicateurs a partir des nombres de naissances officiels publies et de ceux corriges par les auteurs. Ces calculs permettent d'examiner le declin recent de la fecondite chinoise et de montrer que, meme si le probleme de la qualite des donnees est largement repandu, le sous-enregistrement de certaines donnees de fecondite n'est peut-etre pas aussi important que le suggerent les taux bruts de natalite et indicateurs de fecondite corriges officiels. La forte baisse de la fecondite chinoise a commence au debut des annees 1990. L'ISF, au lieu de stagner a 1,8 enfant par femme (chiffre officiel), est tombe au-dessous de 1,7 a la fin de la decennie, et continue de diminuer depuis. Abstract: El estudio de la fecundidad china presenta aspectos sorprendentes desde principios de los anos 1990. Por un lado, los numerosos censos, encuestas de fecundidad y encuestas de poblacion realizados ofrecen datos suficientes para un estudio detallado de la disminucion reciente de la fecundidad; por otro lado, el subregistro y las incoherencias que afectan cada vez mas a los principales datos, constituyen un obstaculo a dichas investigaciones. Estos problemas vienen en parte del hecho que aunque la administracion estadistica ha publicado algunos indices de fecundidad corregidos, es mas bien reacia a dar detalles sobre la tecnica utilizada para efectuar tales ajustes desde los ultimos anos 1990. Este trabajo intenta colmar algunas lagunas en nuestra comprension de los recientes cambios de la fecundidad en China. Examina las incoherencias de los datos de fecundidad provenientes de diferentes fuentes, antes de reconstituir dos series coherentes de indices de fecundidad a partir de los numeros oficiales de nacimientos y de nuestros propios numeros corregidos. Sobre esta base se puede concluir que, si bien la calidad insuficiente de los datos se ha generalizado ampliamente, el subregistro de ciertos datos de fecundidad no puede ser tan importante como lo suponen las correcciones oficiales. Durante los primeros anos 1990, la fecundidad china disminuyo fuertemente. A finales del decenio, el indice sintetico de fecundidad, en lugar de estar estancado en 1,8 hijos por mujer (cifras oficiales), ha pasado por debajo de 1,7 y continua disminuyendo desde entonces.