Home About us Contact
|
Home About us Contact | ||
|
|
||
Defence Mechanisms (defence + mechanism)
Kinds of Defence Mechanisms Selected AbstractsConfronting Social Defence Mechanisms: Avoiding Disorganisation During CrisesJOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 2 2001Martin Loosemore Crises cause social disturbances within their host organisation and the patterns of interpersonal ties that emerge are an important determinant of crisis management efficiency. In this article, social network analysis is used within a construction project context, to demonstrate that efficient crisis management depends upon the design and maintenance of an appropriate social fabric. However, crises have defence mechanisms that make management difficult by inducing forces that encourage people to pursue inappropriate social ties. Purposeful social intervention is therefore an essential part of the crisis management process to confront and avoid disorganisation. [source] Defence mechanisms in schizophreniaPERSONALITY AND MENTAL HEALTH, Issue 4 2008Richard J. Shaw Aim,In this study, the aim was to conduct an empirical study of the nature of defence mechanisms in a group of subjects with schizophrenia. Methods,Forty-four clinically stable, medicated subjects with schizophrenia completed the Response Evaluation Measure (REM-71), a self-report measure used to assess defence mechanisms, and were rated with the Brief Psychiatric Rating Scale (BPRS) to assess severity of psychopathology. Responses on the REM-71 were compared with 136 age and gender-matched control subjects. Results,Subjects with schizophrenia were significantly more likely to endorse the use of immature but not mature defence mechanisms when compared with control subjects (p < 0.001). There was no relationship between responses on the REM-71 and the BPRS. Test,retest reliability of the REM-71 was supported by findings that responses by subjects with schizophrenia were unchanged when reassessed after a two-week time interval. Conclusions,Clinically stable subjects with schizophrenia are found to endorse the use of immature defence mechanisms that have been found to have associations with negative outcomes, including in the area of mood, self-efficacy and quality of life. Defence style may be an important mediator of psychosocial outcomes, and knowledge of specific defence patterns may have important clinical implications for both prognosis and treatment. Copyright © 2008 John Wiley & Sons, Ltd. [source] Cooperation and conflict in host,microbe relationsAPMIS, Issue 5-6 2009ELLING ULVESTAD Hosts and microbes associate in a variety of relations along a continuum ranging from symbiotic to pathogenic. Defence mechanisms have been evolutionarily selected in both hosts and microbes to protect the organism's integrity. Such defences have to be utilized with caution. They must be adapted to the tasks at hand; otherwise any symbiotic relation would be impossible. To explain this cautionary use of defences we need to understand how life on Earth evolved into cooperative and competing entities at various levels of organization. The purpose of this article is to review theory and selected mechanisms relating to the evolution and development of host,microbe interactions, with special emphasis on host responses. The rationale is that without theory, extrapolations from misleading observations can dominate and distort, for a significant time, the course of a scientific field. The argument is set forth that social evolution theory provides a conceptual framework for addressing questions relating to interaction between hosts and microbes. The article is a partial summary of arguments presented in my book Defending life , the nature of host,parasite relations. [source] Effect of thorium on the growth and capsule morphology of BradyrhizobiumENVIRONMENTAL MICROBIOLOGY, Issue 10 2003Mónica Santamaría Summary The thorium effect on Bradyrhizobium growth was assayed in liquid media. Th4+ inhibited the growth of Bradyrhizobium (Chamaecytisus) BGA-1, but this effect decreased in the presence of suspensions of live or dead bacterial cells. Th4+ induced the formation of a gel-like precipitate when added to a dense suspension of B. (Chamaecytisus) BGA-1 cells. Viable Bradyrhizobium cells remained in suspension after precipitate formation. Thorium was recovered in the precipitate, in which polysaccharide, lipopolysaccharide and proteins were also found. After Th4+ addition, the morphology of B. (Chamaecytisus) BGA-1 or Bradyrhizobium japonicum USDA 110 sedimented cells studied by scanning electron microscopy changed from an entangled network of capsulated bacteria to uncapsulated individual cells and an amorphous precipitate. Energy-dispersive X-ray spectroscopy showed that thorium was mainly in the amorphous fraction. Precipitate was also formed between B. (Chamaecytisus) BGA-1 and Al3+, which was also toxic to this bacterium. Precipitate induced by Th4+ or Al3+ was found in all Bradyrhizobium and Sinorhizobium strains tested, but not in Rhizobium, Salmonella typhimurium, Aerobacter aerogenes or Escherichia coli. These results suggest a specific defence mechanism based on metal precipitation by extracellular polymers. [source] Ycf1p-dependent Hg(II) detoxification in Saccharomyces cerevisiaeFEBS JOURNAL, Issue 11 2003Olivier Gueldry In Saccharomyces cerevisiae, disruption of the YCF1 gene increases the sensitivity of cell growth to mercury. Transformation of the resulting ycf1 null mutant with a plasmid harbouring YCF1 under the control of the GAL promoter largely restores the wild-type resistance to the metal ion. The protective effect of Ycf1p against the toxicity of mercury is especially pronounced when yeast cells are grown in rich medium or in minimal medium supplemented with glutathione. Secretory vesicles from S. cerevisiae cells overproducing Ycf1p are shown to exhibit ATP-dependent transport of bis(glutathionato)mercury. Moreover, using ,-galactosidase as a reporter protein, a relationship between mercury addition and the activity of the YCF1 promoter can be shown. Altogether, these observations indicate a defence mechanism involving an induction of the expression of Ycf1p and transport by this protein of mercury,glutathione adducts into the vacuole. Finally, possible coparticipation in mercury tolerance of other ABC proteins sharing close homology with Ycf1p was investigated. Gene disruption experiments enable us to conclude that neither Bpt1p, Yor1p, Ybt1p nor YHL035p plays a major role in the detoxification of mercury. [source] Soil microorganisms in coastal foredunes control the ectoparasitic root-feeding nematode Tylenchorhynchus ventralis by local interactionsFUNCTIONAL ECOLOGY, Issue 3 2009Anna M. Pi, kiewicz Summary 1In natural grassland ecosystems, root-feeding nematodes and insects are the dominant below-ground herbivores. In coastal foredunes, the ectoparasitic nematode Tylenchorhynchus ventralis would be a major root herbivore if not strongly controlled by soil microorganisms. Here, we examined if the suppressive effects of the microbial enemies of T. ventralis act by local interactions such as predation, parasitism or antagonism, or local induction of plant defence, or by non-local interactions, such as systemic effects when microorganisms in one section of the plant roots can affect nematode control in another section of the root system. We show that abundance of T. ventralis in the root zone of the grass Ammophila arenaria is suppressed by local interactions. 2We compared local vs. non-local control of nematodes by a natural community of soil microorganisms in a split-root experiment, where nematodes and microbes were inoculated to the same, or to opposite root compartments. 3The split-root experiment revealed that microorganisms affected T. ventralis numbers only when present in the same root compartment. Therefore, the effects of microorganisms on T. ventralis are due to local interactions and not due to induction of a systemic defence mechanism in the plant host. 4When inoculated together with microorganisms, the nematodes were heavily infected with unknown bacteria and with fungi that resembled the genus Catenaria, suggesting that microorganisms control nematodes through parasitism. However, local defence induction cannot be completely excluded. 5Besides microbial enemies of nematodes, the root zone of A. arenaria also contains plant pathogens. Root biomass was reduced by nematode infection, but also by the combination of nematodes and microorganisms, most likely because the soil pathogens overwhelmed the effects of nematode control on plant production. 6We conclude that there may be a trade-off between beneficial effects of soil microorganisms on the plant host due to nematode control vs. pathogenic effects of soil microorganisms on the plant host. We propose that such trade-offs require more attention when studying below-ground multitrophic interactions. [source] Role of a fetal defence mechanism against oxidative stress in the aetiology of preeclampsiaHISTOPATHOLOGY, Issue 1 2009Christoph Jan Wruck Aims:, Increasing evidence suggests that oxidative stress may play a key role in the aetiology of preeclampsia (PE). The aim of this study was to elucidate the placental defence mechanisms employed against oxidative stress and, in particular, the specific role of nuclear factor erythroid 2-related factor 2 (Nrf2). Methods and results:, Expression of Nrf2 in third-trimester placental tissue was compared in preeclamptic and normal gestation-matched controls. PE was associated with increased Nrf2 activity within cytotrophoblastic nuclei. Nrf2 expression was restricted to proliferative and early post-proliferative cytotrophoblast only. Syncytiotrophoblast was immunonegative for Nrf2 in both controls and preeclamptic placentas. Conclusions:, Nrf2 is exclusively active within cytotrophoblast, strongly suggesting that these cells are the origin of Nrf2-dependent gene products. Syncytiotrophoblast is transcriptionally inactive; therefore in times of oxidative stress essential cytoprotective enzymes must be derived from the cytotrophoblast. Excessive cytotrophoblastic turnover causes disproportionate release of toxic placental factors, manifesting as PE and endangering maternal health. Increased cytotrophoblastic proliferation/fusion could thus be interpreted as a fetal defence mechanism, initiated in response to the requirements of vulnerable syncytiotrophoblast. We therefore propose a direct relationship between fetal defence against oxidative stress and consequent placental toxicity as part of the aetiology of this complex maternal disease. [source] ,, T-cell anergy in human immunodeficiency virus-infected persons with opportunistic infections and recovery after highly active antiretroviral therapyIMMUNOLOGY, Issue 4 2000F. Martini Summary ,, T lymphocytes recognize non-peptidic microbial antigens without antigen processing and major histocompatibility complex (MHC) restriction, representing an early defence mechanism against invading pathogens. As a defective response to non-peptidic antigens was observed in human immunodeficiency virus-positive (HIV+) persons, the aims of this study were twofold: to analyse the incidence of ,, T-cell anergy in HIV+ patients with opportunistic infections/co-infections (HIV-OIC), and to investigate the role of highly active antiretroviral therapy (HAART) on ,, T-cell functions. Peripheral ,, T-cell distribution and in vitro reactivity to a non-peptidic mycobacterial antigen, isopentenyl pyrophosphate (IPP), were analysed. ,, T-cell subset distribution was altered more in HIV-OIC patients than in asymptomatic HIV+ subjects (HIV-ASY). Specifically, the V,2/V,1 ratio was inverted as a consequence of a decrease in V,2 T-cell number. Moreover, IPP-stimulated V,2 T cells from the HIV-OIC group displayed a major defect in interferon-, (IFN-,) production. Interestingly, HAART induced a sustained recovery of naive CD45RA+ and CD62L+ T cells and restored ,, T-cell function. Accordingly, in vitro CD45RA depletion resulted in ,, T-cell hyporesponsiveness. Altogether, the incidence of ,, T-cell anergy was increased in HIV-OIC patients and dependent on CD45RA helper function. Moreover, HAART was able to restore ,, T-cell reactivity, extending the immune recovery to non-peptidic microbial antigens. [source] Bacterial enteritis and the development of the larval digestive tract in olive flounder, Paralichthys olivaceus (Temminck & Schlegel)JOURNAL OF FISH DISEASES, Issue 9 2004D-H Kim Abstract Three bacterial isolates obtained from diseased olive flounder larvae, Paralichthys olivaceus, were identified as Vibrio ichthyoenteri based on the results of phenotypic characterization and 16S rRNA gene sequencing studies. Bacterial enteritis was reproduced in 16 and 22 days post-hatch (dph) larvae by administering brine shrimp nauplii, Artemia salina, dosed with the environmental isolates and reference strains of V. ichthyoenteri. To investigate the effect of the disease on development of the stomach, a pepsin activity assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis of the expression of the pepsinogen gene were performed. Expression of olive flounder pepsinogen was detected from 30-dph larvae and the increased level of pepsin activity coincided with reduced susceptibility to the disease. Growth rates of V. ichthyoenteri, V. anguillarum and Edwardsiella tarda were tested in artificial stomach conditions using HCl and porcine pepsin. All the strains of V. ichthyoenteri were inhibited by low pH conditions which corresponded with an increase in pepsin levels. This suggests that differentiation of the stomach in olive flounder larvae and juveniles, an essential physiological development, also provides the host with a non-immunological defence mechanism. [source] Trichomes of Lycopersicon species and their hybrids: effects on pests and natural enemiesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2006Aaron T. Simmons Abstract 1,The cultivated tomato, Lycopersicon esculentum, is an economically important worldwide crop. Current pest management techniques rely heavily on pesticides but trichome-based host-plant resistance may reduce pesticide use. 2,A review of the literature is provided on trichomes of wild Lycopersicon species and the effects of trichome-based host-plant resistance on arthropods. Solvents have been used to remove glandular trichome exudates and the resulting dimminution of their effects quantified. Correlational approaches to assess the relationship between the different trichome types and effects on pests have also been used. 3,Most studies have focused on Lepidoptera and Hemiptera, although some work has included Coleoptera, Diptera and Acarina, and both antibiotic and antixenotic effects have been demonstrated. 4,Natural enemies are a cornerstone of international pest management and this review discusses how the compatibility of this approach with trichome-based host-plant resistance is uncertain because of the reported negative effects of trichomes on one dipteran, one hemipteran and several Hymenoptera. 5,For trichome-based host-plant resistance to be utilized as a pest management tool, trichomes of wild species need to be introgressed into the cultivated tomato. Hybrids between the cultivated tomato and the wild species Lycopersicon hirsutum f. glabratum, Lycopersicon pennellii and Lycopersicon cheesmanii f. minor have been produced and useful levels of resistance to Acarina, Diptera and Hemiptera pests have been exhibited, although these effects may be tempered by effects on natural enemies. 6,This review proposes that studies on genetic links between fruit quality and resistance, field studies to determine the compatibility of natural enemies and trichome-based host-plant resistance, and a strong focus on L. cheesmanii f. minor, are all priorities for further research that will help realize the potential of this natural defence mechanism in pest management. [source] Hypersensitivity of Plum Genotypes to Plum Pox VirusJOURNAL OF PHYTOPATHOLOGY, Issue 3-4 2001Kegler The hypersensitive response (HR) of plum hybrid K4 as an active defence mechanism is directed against certain plum pox virus (PPV) strains/isolates of the type CG but not against type DI. There is no clear correlation between the HR of K4 and serological differences of the PPV strains D, M and C, respectively. A total of 14 genotypes out of 21 progenies of K4 reacted necrotically and were proved to be either hypersensitive and field resistant or highly sensitive and not field resistant. The HR can be connected with a complete or with an incomplete virus localization in K4 and some of its progenies. The remaining genotypes were more or less sensitive and tolerant, respectively. Growth of buds from PPV-CG-infected plum cultivars on K4 differed in the degree of systemic virus invasion in the plant as a trait of quantitative virus resistance. The percentage of growing buds correlated with the level of quantitative PPV resistance. [source] Apoptosis in hepatitis CJOURNAL OF VIRAL HEPATITIS, Issue 5 2003J. Kountouras Summary. The apoptotic process appears to be a host defence mechanism against viral infections and tumourigenesis. However, many viral genomes encode proteins, which repress apoptosis so as to escape from immune attack by the host. Therefore, virus,host interactions may determine viral persistence, extent and severity of liver inflammation and possibly viral hepatocarcinogenesis. Apoptosis of liver cells may play a significant role in the pathogenesis of hepatitis C. Pathomorphologic features of increased apoptosis include shrinkage and fragmentation of nuclei/cytoplasm in piecemeal necrosis areas, acidophilic bodies, and focal cell dropout in the liver lobule. The hepatitis C virus (HCV) core protein exhibits both proapoptotic or antiapoptotic actions. Modulation of apoptosis may involve binding of HCV core protein to the intracellular signal transducing portion of death receptors and displacement of signalling molecules. Apoptosis may occur in the absence of significant transaminase elevation, thereby explaining the lack of correlation between biochemical activity and liver cell histological injury. Monitoring caspase activation might provide a reliable tool to estimate the efficacy of HCV therapy, and might open challenging therapeutic strategies in HCV infection. The antiviral effect of interferon may be mediated through induction of apoptosis. Lastly, administration of the antiapoptotic ursodeoxycholic acid in HCV infection is compatible with the notion that apoptosis may represent a mechanism for viral shedding rather than for viral elimination, thereby raising the concept that inhibition of apoptosis could ameliorate hepatitis C. [source] Disease resistance to bacterial pathogens affected by the amount of ferredoxin-I protein in plantsMOLECULAR PLANT PATHOLOGY, Issue 1 2007HSIANG-EN HUANG SUMMARY Ferredoxin-I (Fd-I) is a fundamental protein that is involved in several metabolic pathways. The amount of Fd-I found in plants is generally regulated by environmental stress, including biotic and abiotic events. In this study, the correlation between quantity of Fd-I and plant disease resistance was investigated. Fd-I levels were increased by inoculation with Pseudomonas syringae pv. syringae but were reduced by Erwinia carotovora ssp. carotovora. Transgenic tobacco over-expressing Fd-I with the sense sweet pepper Fd-I gene (pflp) was resistant to E. carotovora ssp. carotovora and the saprophytic bacterium P. fluorescens. By contrast, transgenic tobacco with reduced total Fd-I and the antisense pflp gene was susceptible to E. carotovora ssp. carotovora and P. fluorescens. Both of these transgenic tobaccos were resistant to P. syringae pv. syringae. By contrast, the mutated E. carotovora ssp. carotovora, with a defective harpin protein, was able to invade the sense- pflp transgenic tobacco as well as the non-transgenic tobacco. An in vitro kinase assay revealed that harpin could activate unidentified kinases to phosphorylate PFLP. These results demonstrate that Fd-I plays an important role in the disease defence mechanism. [source] Review: Autophagy in neurodegeneration: firefighter and/or incendiarist?NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2009A. Rami Autophagy is an intracellular bulk degradation system that is found ubiquitously in eukaryotes. Autophagy is responsible for the degradation of most long-lived proteins and some organelles. Cytoplasmic constituents, including organelles, are sequestered into double-membrane autophagosomes, which subsequently fuse with lysosomes where their contents are degraded. This system has been implicated in various physiological processes including protein and organelle turnover, stress response, cellular differentiation, programmed cell death and pathological conditions. Defects in the autophagy machinery might have several consequences, as they have been associated with neurodegenerative disease and different forms of cancer. Thus, autophagy occupies a crucial position within the cell's metabolism, and its modulation may represent an alternative therapeutic strategy in several pathological settings including stroke, Alzheimer's, Huntington's, Parkinson's diseases and cancer. Recently, research has begun to identify some characteristics of neuronal autophagy. The results suggest that autophagy may provide a neuroprotective mechanism. However, there is evidence showing that dysfunction of autophagy in certain pathological situations can trigger and mediate programmed cell death. Autophagy has also been defined as prime suspect cause of non-apoptotic cellular demise. However, there is now mounting evidence that autophagy and apoptosis share several common regulatory elements that are crucial in any attempt to understand the dual role of autophagy in cell death and cell survival. It will be of fundamental importance to dissect whether autophagy is primarily a strategy for survival or whether autophagy can also be a part of a cell death programme and thus contribute to cell death. Many questions are open. Is autophagy a direct death execution pathway? Is autophagy an innocent bystander? Is autophagy a defence mechanism or just a scavenger or self-clearance tool in the cell? A profound understanding of the biological effects and the mechanisms underlying autophagy in neurones might be helpful in seeking effective new treatments for neurodegenerative diseases. Here, we review the defining characteristics of autophagy with special attention to its role in neurodegenerative disorders, and recent efforts to delineate the pathway of autophagic protein degradation in neurone. [source] AGGREGATION BEHAVIOUR IN JUVENILE MILLIPEDES FROM THE UPPER CARBONIFEROUS OF MAZON CREEK, ILLINOISPALAEONTOLOGY, Issue 4 2006HEATHER M. WILSON Abstract:, Two ironstone nodules are described from the Braidwood Biota of the Upper Carboniferous Mazon Creek Lagerstätte, Illinois, each preserving numerous juvenile millipedes referred to Euphoberia sp. The millipedes belong to different stadia, as evidenced by segment number, but are similar in size so probably nearly the same age. These juvenile euphoberiids differ from adults in having shorter pleurotergal spines, a reduced number of ocelli and a series of reduced, apodous trunk rings posteriorly. These nodules provide the first evidence of aggregation behaviour in Palaeozoic millipedes. Aggregation in juvenile euphoberiids is hypothesized to serve as a defence mechanism, compensating for the reduced length of their pleurotergal spines relative to adults, possibly through a collective chemical defence. [source] Local early induced resistance of plants as the first line of defence against bacteria,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2003Zoltán Klement Abstract This paper is an overview of a non-specific local early induced resistance (EIR) mechanism, distinct from the incompatible-specific hypersensitive reaction (HR). We have shown that the local induced resistance (LIR) described earlier is not a single and uniform response to pathogen infection, because an early (EIR) and a late form can be distinguished. EIR operates from 3,6,h post-inoculation (hpi) until about 20,hpi, and is inhibited by a short heat-shock or the eukaryotic protein synthesis inhibitor, cycloheximide. In contrast, LIR, which corresponds to the induced resistance forms discovered earlier, requires more time (about 24,h) and intensive illumination to develop, and is effective for a longer period. EIR develops parallel with HR and is sometimes able to prevent it when the induction time of HR is longer than the time required for the development of EIR. It seems that EIR inhibits the metabolism of bacteria and the activity of hrp genes which otherwise are required for the induction of HR. In a compatible host,pathogen relationship the effect of EIR fails to take place. The rapid development of EIR is greatly influenced by temperature and the physiological state of the plant. EIR activates the accumulation of hydrogen peroxide at the bacterial attachment, expressing new peroxidase isoenzymes in the initiated plant tissue. It seems that this is a native general local defence mechanism which can localise foreign organisms even at the penetration site. © 2003 Society of Chemical Industry [source] Apical leaf necrosis as a defence mechanism against pathogen attack: effects of high nutrient availability on onset and rate of necrosisPLANT PATHOLOGY, Issue 6 2008F. Van Den Berg An outdoor experiment was conducted to increase understanding of apical leaf necrosis in the presence of pathogen infection. Holcus lanatus seeds and Puccinia coronata spores were collected from two adjacent and otherwise similar habitats with differing long-term N fertilization levels. After inoculation, disease and necrosis dynamics were observed during the plant growing seasons of 2003 and 2006. In both years high nutrient availability resulted in earlier disease onset, a higher pathogen population growth rate, earlier physiological apical leaf necrosis onset and a reduced time between disease onset and apical leaf necrosis onset. Necrosis rate was shown to be independent of nutrient availability. The results showed that in these nutrient-rich habitats H. lanatus plants adopted necrosis mechanisms which wasted more nutrients. There was some indication that these necrosis mechanisms were subject to local selection pressures, but these results were not conclusive. The findings of this study are consistent with apical leaf necrosis being an evolved defence mechanism. [source] Denial in cancer patients, an explorative reviewPSYCHO-ONCOLOGY, Issue 1 2007M. S. Vos Abstract Denial is a clinically relevant concept in cancer patients. It has been investigated and discussed extensively. Its definition, however, has been subject to different theoretical trends over time. From a psychoanalytical viewpoint, denial is a pathological, ineffective defence mechanism. On the other hand, according to the stress and coping model denial can be seen as an adaptive strategy to protect against overwhelming events and feelings. In this explorative review the different concepts and the prevalence of denial in cancer patients are described. The relationship between denial and background characteristics and the influence of denial on quality of life are reviewed also. The prevalence of denial of diagnosis in cancer patients ranged from 4 to 47%, denial of impact occurred 8,70% and denial of affect in 18,42% of patients. Elderly cancer patients were more likely to deny. Cultural background seemed to play a role in the prevalence of denial. Neither type of cancer nor gender seemed to be related to denial. At the most, men might be more likely to deny during the terminal phase. In a limited number of longitudinal studies, a gradual reduction in denial was found over the course of the illness. The effect of denial on physical and social functioning remained unclear while the effect on psychological functioning seemed to depend on the concept of denial used. Distractive strategies were found to reduce distress, whereas passive escape mechanisms turned out to decrease psychological well-being. Future research on the prevalence and the (mal)adaptive properties of denial in cancer patients has to be based on a clear concept, longitudinal designs and careful recording of background variables. Copyright © 2006 John Wiley & Sons, Ltd. [source] Induced systemic resistance against three foliar diseases of Agrostis stolonifera by (2R,3R)-butanediol or an isoparaffin mixtureANNALS OF APPLIED BIOLOGY, Issue 2 2010A.M. Cortes-Barco Induced systemic resistance (ISR) is a type of plant defence mechanism typically activated by non-pathogenic root-associated micro-organisms and systemic priming of gene expression in response to subsequent pathogen challenge. ISR was found to be activated by PC1, a mixture of food-grade synthetic isoparaffins and (2R,3R)-butanediol, a volatile organic compound produced by bacteria. In controlled environment tests, application of PC1 or (2R,3R)-butanediol to the soil reduced the diseased leaf area of Agrostis stolonifera by 20,40% for the fungal pathogens, Microdochium nivale, Rhizoctonia solani or Sclerotinia homoeocarpa compared to the water control. In A. stolonifera, expression of the jasmonate synthesis-related genes, AsAOS1, encoding an allene oxide synthase, and AsOPR4, encoding a 12-oxo-phytodienoic acid reductase, and expression of a pathogenesis-related protein gene, AsGns5, encoding an acidic , -1,3-glucanase, were primed for increased expression by PC1 or (2R,3R)-butanediol when M. nivale was inoculated 7 days later. However, the compounds differed in their ability to induce expression prior to pathogen challenge. PC1 induced AsAOS1 expression upon treatment, whereas (2R,3R)-butanediol induced expression of AsOPR4 and AsGns5 upon treatment. These results indicate that both (2R,3R)-butanediol and PC1 can produce ISR in A. stolonifera but may do so through different mechanisms. [source] Structure of a yellow lupin pathogenesis-related PR-10 protein belonging to a novel subclassACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2005Oliwia Pasternak Pathogenesis-related (PR) proteins of class 10 are abundant in higher plants. Some of these proteins are induced under stress conditions as part of the plant defence mechanism. Other homologues are developmentally regulated and their expression varies in different plant organs. The PR-10 proteins are encoded by multigene families, have a weight of about 17,kDa and are found in the cytosol. In yellow lupin, nine different homologues have been identified and divided into two subclasses, LlPR-10.1 and LlPR-10.2. Within each subclass the sequence identity is about 75,91%, while across the subclasses it is only 59,60%. Here, the crystal structure of a yellow lupin PR-10 protein from the second subclass, LlPR-10.2A, is presented. The structure was solved by molecular replacement and refined to R = 0.205 using 1.9,Ĺ resolution data. The general fold of LlPR-10.2A resembles that of the other PR-10 proteins and consists of a long C-terminal ,-helix surrounded by a seven-stranded antiparallel ,-sheet, with two shorter ,-helices located between strands ,1 and ,2. The most variable part of the structure, the C-terminal helix, is strongly kinked towards the ,-sheet core in both LlPR-10.2A molecules present in the asymmetric unit. This unexpected feature reduces the size of the hydrophobic cavity observed in other PR-10 proteins that is reported to be the ligand-binding site. As in other PR-10 structures, a surface loop located near the entrance to the cavity shows very high structural conservation and stability despite the high glycine content in its sequence. [source] Hepatoprotective Activity of Polyherbal Formulation (Normeta®) in Oxidative Stress Induced by Alcohol, Polyunsaturated Fatty Acids and Iron in RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2009Shilpa N. Patere The present study was carried out to evaluate the effects of oral treatment with polyherbal formulation Normeta® (2 ml and 4 ml/kg) on hepatic damage induced by alcohol 10,30% (blood alcohol was maintained at levels between 150 and 350 mg/dl), thermally oxidized oil (polyunsaturated fatty acids) (15% of diet) and carbonyl iron (1.5,2% of diet) for 30 days in rats. In vitro studies with 1, 1-Diphenyl, 2-Picrylhydrazyl (DPPH), Nitric oxide and Ferric chloride (Fe+3 ions) showed that Normeta® possesses antioxidant and metal chelating activity. Alcohol, polyunsaturated fatty acids and iron feeding produced an increase in serum levels of iron, serum glutamate pyruvate transaminase and decrease in serum proteins. It was also associated with elevated lipid peroxidation (thiobarbituric acid reactive substances) and disruption of antioxidant defence mechanism in liver, decreased body weight and increased liver to body weight ratio. Oral administration of Normeta® along with alcohol, polyunsaturated fatty acids and iron decreased the serum iron, serum glutamate pyruvate transaminase levels and increased serum protein levels. The levels of liver thiobarbituric acid reactive substances were decreased and the activities of antioxidant enzymes superoxide dismutase and catalase were increased. Improvement in body weight and liver to body weight ratio was also observed. The effects of Normeta® on physico-metabolic parameters were comparable with silymarin. This indicates that Normeta® has favourable effect in bringing down the severity of hepatotoxicity. [source] The evolution of conspicuous facultative mimicry in octopuses: an example of secondary adaptation?BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010CHRISTINE L. HUFFARD The ,Mimic Octopus'Thaumoctopus mimicus Norman & Hochberg, 2005 exhibits a conspicuous primary defence mechanism (high-contrast colour pattern during ,flatfish swimming') that may involve facultative imperfect mimicry of conspicuous and/or inconspicuous models, both toxic and non-toxic (Soleidae and Bothidae). Here, we examine relationships between behavioural and morphological elements of conspicuous flatfish swimming in extant octopodids (Cephalopoda: Octopodidae), and reconstructed ancestral states, to examine potential influences on the evolution of this rare defence mechanism. We address the order of trait distribution to explore whether conspicuous flatfish swimming may be an exaptation that usurps a previously evolved form of locomotion for a new purpose. Contrary to our predictions, based on the relationships we examined, flatfish swimming appears to have evolved concurrently with extremely long arms, in a clade of sand-dwelling species. The conspicuous body colour pattern displayed by swimming T. mimicus may represent a secondary adaptation potentially allowing for mimicry of a toxic sole, improved disruptive coloration, and/or aposematic coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 68,77. [source] Host plant adaptations in myrtaceous-feeding Pergid sawflies: essential oils and the morphology and behaviour of Pergagrapta larvae (Hymenoptera, Symphyta, Pergidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2000S. SCHMIDT Australian pergine sawflies typically feed on eucalypts and other closely-related Myrtaceae, which are known for their high content of essential oils. We describe a novel morphological adaptation of the inner mandibular surface of larval stage Pergagrapta species, which feed on leaves of Melaleuca quinquenervia (Myrtaceae). This ,scopa mandibularis' forms an extensive mesh of setaceous papillae on what is usually the grinding surface of the mandible. Behavioural, chemical and morphological investigations of the sawfly- Melaleuca system suggest that the scopa may function in the physical separation of toxic leaf oils from the diet. The oils are stored in a pharyngeal diverticulum from where they are ejected under two circumstances. Oil from the diverticulum is voided prior to feeding and/or during feeding at night, which indicates a mechanism to eliminate host-associated oils. Larvae rest in close aggregations during the day, when they retain a full diverticulum, but the oils may be emitted for defensive purposes when larvae are disturbed. Chemical evidence suggests that 1,8-cineole, the major component in the M. quinquenervia leaves, is selectively metabolized to a more soluble hydroxycineole. We postulate that the separation and regurgitation of oils is not only a defence mechanism against predators, as usually stated, but also a mechanism by which pergid larvae eliminate oils from their diet, to reduce the toxicity of their food plants. [source] Origin and evolution of the protein-repairing enzymes methionine sulphoxide reductasesBIOLOGICAL REVIEWS, Issue 3 2008Xing-Hai Zhang Abstract The majority of extant life forms thrive in an O2 -rich environment, which unavoidably induces the production of reactive oxygen species (ROS) during cellular activities. ROS readily oxidize methionine (Met) residues in proteins/peptides to form methionine sulphoxide [Met(O)] that can lead to impaired protein function. Two methionine sulphoxide reductases, MsrA and MsrB, catalyse the reduction of the S and R epimers, respectively, of Met(O) in proteins to Met. The Msr system has two known functions in protecting cells against oxidative damage. The first is to repair proteins that have lost activity due to Met oxidation and the second is to function as part of a scavenger system to remove ROS through the reversible oxidation/reduction of Met residues in proteins. Bacterial, plant and animal cells lacking MsrA are known to be more sensitive to oxidative stress. The Msr system is considered an important cellular defence mechanism to protect against oxidative stress and may be involved in ageing/senescence. MsrA is present in all known eukaryotes and eubacteria and a majority of archaea, reflecting its essential role in cellular life. MsrB is found in all eukaryotes and the majority of eubacteria and archaea but is absent in some eubacteria and archaea, which may imply a less important role of MsrB compared to MsrA. MsrA and MsrB share no sequence or structure homology, and therefore probably emerged as a result of independent evolutionary events. The fact that some archaea lack msr genes raises the question of how these archaea cope with oxidative damage to proteins and consequently of the significance of msr evolution in oxic eukaryotes dealing with oxidative stress. Our best hypothesis is that the presence of ROS-destroying enzymes such as peroxiredoxins and a lower dissolved O2 concentration in those msr -lacking organisms grown at high temperatures might account for the successful survival of these organisms under oxidative stress. [source] Human and bovine lactoferrins in the milk of recombinant human lactoferrin-transgenic dairy cows during lactationBIOTECHNOLOGY JOURNAL, Issue 4 2006Paula Hyvönen Abstract Seven Friesian human lactoferrin (hLf)-transgenic primiparous dairy cows expressing recombinant hLf (rhLf) in their milk were included in the study. After calving, concentrations of rhLf and bovine LF (bLf) in the milk, somatic cell count and milk yield were determined. The concentration of rhLf was found to be constant, about 2.9 mg/mL, throughout the early lactation period of 3 months. The concentration of bLf in colostrum was higher after calving, but decreased rapidly during the first days of lactation. The mean concentration of bLf was 0.15 mg/mL, but concentrations varied between cows from 0.07 mg/mL to 0.26 mg/mL. Based on that, it may be possible to improve the non-specific host defence mechanism in the mammary gland of dairy cows by enhancing the content of rhLf in the milk. [source] A major role for intestinal epithelial nucleotide oligomerization domain 1 (NOD1) in eliciting host bactericidal immune responses to Campylobacter jejuniCELLULAR MICROBIOLOGY, Issue 10 2007Matthias Zilbauer Summary Campylobacter jejuni is the foremost cause of bacterial-induced diarrhoeal disease worldwide. Although it is well established that C. jejuni infection of intestinal epithelia triggers host innate immune responses, the mechanism(s) involved remain poorly defined. Innate immunity can be initiated by families of structurally related pattern-recognition receptors (PRRs) that recognize specific microbial signature motifs. Here, we demonstrated maximal induction of epithelial innate responses during infection with live C. jejuni cells. In contrast when intestinal epithelial cells (IECs) were exposed to paraformaldehyde-fixed bacteria, host responses were minimal and a marked reduction in the number of intracellular bacteria was noted in parallel. These findings suggested a role for intracellular host,C. jejuni interactions in eliciting early innate immunity. We therefore investigated the potential involvement of a family of intracellular, cytoplasmic PRRs, the nucleotide-binding oligomerization domain (NOD) proteins in C. jejuni recognition. We identified NOD1, but not NOD2, as a major PRR for C. jejuni in IEC. We also found that targeting intestinal epithelial NOD1 with small interfering RNA resulted in an increase in number of intracellular C. jejuni, thus highlighting a critical role for NOD1-mediated antimicrobial defence mechanism(s) in combating this infection at the gastrointestinal mucosal surface. [source] Proteases in pathogenesis and plant defenceCELLULAR MICROBIOLOGY, Issue 10 2004Yiji Xia Summary Plant pathogens deliver a variety of virulence factors to host cells to suppress basal defence responses and create suitable environments for their propagation. Plants have in turn evolved disease resistance genes whose products detect the virulence factors as a signal of invasion and activate effective defence responses. Understanding how a virulence effector contributes to virulence on susceptible hosts but becomes an avirulence factor that triggers defence responses on resistance hosts has been a major focus in plant research. Recent studies have shown that a growing list of pathogen-encoded effectors functions as proteases that are secreted into plant cells to modify host proteins. In addition, several plant proteases have been found to function in activation of the defence mechanism. These findings reveal that post-translational modification of host proteins through proteolytic processing is a widely used mechanism in regulating the plant defence response. [source] Airway microvascular extravasation and luminal entry of plasmaCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2003Lennart Greiff Summary Extravasation of plasma from postcapillary venules is a specific in vivo response to inflammatory insults. In the nasal and bronchial airways, extravasated plasma has a widespread distribution in the lamina propria, between the epithelial cells and in the airway lumen. This feature, in combination with the fact that the process involves extravasation of bulk plasma, with all peptides and proteins of plasma, indicates that plasma exudation contributes to the dramatic change of the mucosal milieu that characterizes airway inflammation. Accordingly, this process is of key importance to conditions such as allergic rhinitis and asthma. The means by which extravasated plasma participates in mucosal defence is physiological in the sense that it may operate on the surface of the epithelium without impairing its function as an absorption barrier. The flow of plasma into the airway lumen may thus wash away unwanted material from inter-epithelial cell spaces, exuded binding proteins may bind unwanted solutes non-specifically and extravasated immunoglobulins may neutralize allergens. In addition to the role as defence mechanism, extravasated plasma components may act as important pro-inflammatory factors. Furthermore, experimental data as well as observations in natural disease suggest that luminal levels of plasma proteins can be employed as an accessible index reflecting to what degree the airway mucosa is affected by inflammatory processes. [source] Browsing in a heterogeneons savannaECOGRAPHY, Issue 5 2000C. Skarpe Large herbivores generally depend on and interact with a food resource that is heterogeneous at different spatial scales. Plants allocate resources to rapid growth or to defence mechanisms depending on the availability of resources relative to loss of resources from herbivory. Herbivores select food and feeding habitats in order to maximize intake rate of nutrients and digestible energy, while avoiding chemical and structural deterrents. To optimize foraging, herbivores select habitats and food items in a hierarchical way, and different attracting and deterring factors may govern selection at different scales. We studied the impact of twig biting by a guild of indigenous browsers in three vegetation types in a semi-arid savanna in Botswana. The heaviest browsing pressure was in the vegetation type richest in preferred plant species, although that type was also richest in defended species. There were large differences in relative utilization between plant species, and ranking of species was roughly similar in the different vegetation types. Browsing pressure varied between species from almost 0-30%. Overall, spinescent trees were less browsed than non-spinescent ones, and evergreen species were less browsed than deciduous ones. In two of the three vegetation types there was a negative correlation between browsing pressure on a species and its frequency. There was a high incidence of rebrowsing, and once a tree had been browsed, the probability that it would be browsed again increased. The results largely agree with predictions based on the resource availability hypothesis, the scarcity accessibility hypothesis and recent theories on the significance of plant defences and on plant's response to browsing and the subsequent response by herbivores on the plant's responses. [source] Plant biological warfare: thorns inject pathogenic bacteria into herbivoresENVIRONMENTAL MICROBIOLOGY, Issue 3 2007Malka Halpern Summary Thorns, spines and prickles are among the rich arsenal of antiherbivore defence mechanisms that plants have evolved. Many of these thorns are aposematic, that is, marked by various types of warning coloration. This coloration was recently proposed to deter large herbivores. Yet, the mechanical defence provided by thorns against large herbivores might be only the tip of the iceberg in a much more complicated story. Here we present evidence that thorns harbour an array of pathogenic bacteria that are much more dangerous to herbivores than the painful mechanical wounding by the thorns. Pathogenic bacteria like Clostridium perfringens, the causative agent of the life-threatening gas gangrene, and others, were isolated and identified from date palm (with green-yellow-black aposematic spines) and common hawthorn (with red aposematic thorns). These thorn-inhabiting bacteria have a considerable potential role in antiherbivory, and may have uniquely contributed to the common evolution of aposematism (warning coloration) in thorny plants. [source] | |||||||||||||||||||||||||||||||||||||