Root-expressed maize lipoxygenase 3 negatively regulates induced systemic resistance to Colletotrichum graminicola in shoots

We have previously reported that disruption of a maize root-expressed 9-lipoxygenase (9-LOX) gene, ZmLOX3, results in dramatic increase in resistance to diverse leaf and stalk pathogens. Despite evident economic significance of these findings, the mechanism behind this increased resistance remained elusive. In this study, we found that increased resistance of the lox3-4 mutants is due to constitutive activation of induced systemic resistance (ISR) signaling. We showed that ZmLOX3 lacked expression in leaves in response to anthracnose leaf blight pathogen Colletotrichum graminicola, but was expressed constitutively in the roots, thus, prompting our hypothesis: the roots of lox3-4 mutants are the source of increased resistance in leaves. Supporting this hypothesis, treatment of wild-type plants (WT) with xylem sap of lox3-4 mutant induced resistance to C. graminicola to the levels comparable to those observed in lox3-4 mutant. Moreover, treating mutants with the sap collected from WT plants partially restored the susceptibility to C. graminicola. lox3-4 mutants showed primed defense responses upon infection, which included earlier and greater induction of defense-related PAL and GST genes compared to WT. In addition to the greater expression of the octadecanoid pathway genes, lox3-4 mutant responded earlier and with a greater accumulation of H(2)O(2) in response to C. graminicola infection or treatment with alamethicin. These findings suggest that lox3-4 mutants display constitutive ISR-like signaling. In support of this idea, root colonization by Trichoderma virens strain GV29-8 induced the same level of disease resistance in WT as the treatment with the mutant sap, but had no additional resistance effect in lox3-4 mutant. While treatment with T. virens GV29 strongly and rapidly suppressed ZmLOX3 expression in hydroponically grown WT roots, T. virens Δsml mutant, which is deficient in ISR induction, was unable to suppress expression of ZmLOX3, thus, providing genetic evidence that SM1 function in ISR, at least in part, by suppressing host ZmLOX3 gene. This study and the genetic tools generated herein will allow the identification of the signals regulating the induction of resistance to aboveground attackers by beneficial soil microorganisms in the future

Conflict transformation and history teaching: social psychological theory and its contributions

The aim of this introductory chapter is to render intelligible how history teaching can be enriched with knowledge of social psychological theories that deal with the issue of conflict transformation and partcularly the notions of prejudice reduction and reconciliation. A major aim of history teaching is to engage students with historical texts, establish historical significance, identify continuity and change, analyse cause and consequence, take historical perspectives and understand the ethical dimensions of historical interpretations. Such teaching, enriched with social psychological theory, will enlarge the notion of historical literacy into a study of historical culture and historical consciousness in the classroom so that students become reflective of the role of collective memory and history teaching in processes of conflict transformation and understand the ways in which various forms of historical consciousness relate the past, present and future. This is what the editors of this volume call an interdisciplinary paradigm of transformative history teachin

Binding of Superantigen Toxins into the CD28 Homodimer Interface Is Essential for Induction of Cytokine Genes That Mediate Lethal Shock

Bacterial superantigen toxins bind directly to the dimer interface of CD28, the principal co-stimulatory receptor, to induce a lethal cytokine storm, and peptides that prevent this binding can suppress superantigen lethality

An analysis of the Notre Dame Educational Association achievement test in Physics

This study analyzes and interprets the Notre Dame Educational Association (NDEA) achievement test in physics for high school.The subjects were 400 graduating high school students of the eight Notre Dame schools in South Cotabato.On the basis of responses of the examinees, the following were computed: discrimination index, difficulty index, attractiveness of the options and Kuder-Richardson Formula 20 reliability coefficient.For examining the structural characteristics of the items, the classification scheme included the following three areas: knowledge, comprehension, and application.To test the concurrent validity, Pearson product-moment correlation coefficient was calculated between achievement test scores and the students grade point averages in physics.The following conclusions were made:1. There is a need to revise forty-three (43) items or 71.67 percent of the total number of test items.2. While the instrument was found to be reliable, the test has too many (51.67 percent) items testing for knowledge, only 21.67 percent testing for comprehension, and 26.67 percent testing for application.3. The relationship between achievement test scores and the grade point averages in physics is significant at 0.01 level of confidence.On the basis of the information obtained from this study, the following recommendations are hereby suggested.1. The NDEA should form a Committee to make the final revision of the test with a well-trained consultant.2. Revised version of the test should be subjected to further content analysis. 3. The NDEA should construct or develop more physics achievement test of parallel for to safeguard the reliability of the said test.The NDEA achievement test on other subject areas should be subjected to item analysis. There is a possibility that further improvement can be done on those test

Dual-topology insertion of a dual-topology membrane protein

Some membrane transporters are dual-topology dimers in which the subunits have inverted transmembrane topology. How a cell manages to generate equal populations of two opposite topologies from the same polypeptide chain remains unclear. For the dual-topology transporter EmrE, the evidence to date remains consistent with two extreme models. A post-translational model posits that topology remains malleable after synthesis and becomes fixed once the dimer forms. A second, co-translational model, posits that the protein inserts in both topologies in equal proportions. Here we show that while there is at least some limited topological malleability, the co-translational model likely dominates under normal circumstances