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Sample records for adaptive defense mechanisms

  1. Defense Mechanisms: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    This bibliography includes studies of defense mechanisms, in general, and studies of multiple mechanisms. Defense mechanisms, briefly and simply defined, are the unconscious ego defendants against unpleasure, threat, or anxiety. Sigmund Freud deserves the clinical credit for studying many mechanisms and introducing them in professional literature.…

  2. Tissue-specific defense and thermo-adaptive mechanisms of soybean seedlings under heat stress revealed by proteomic approach.

    PubMed

    Ahsan, Nagib; Donnart, Tifenn; Nouri, Mohammad-Zaman; Komatsu, Setsuko

    2010-08-01

    A comparative proteomic approach was employed to explore tissue-specific protein expression patterns in soybean seedlings under heat stress. The changes in the protein expression profiles of soybean seedling leaves, stems, and roots were analyzed after exposure to high temperatures. A total of 54, 35, and 61 differentially expressed proteins were identified from heat-treated leaves, stems, and roots, respectively. Differentially expressed heat shock proteins (HSPs) and proteins involved in antioxidant defense were mostly up-regulated, whereas proteins associated with photosynthesis, secondary metabolism, and amino acid and protein biosynthesis were down-regulated in response to heat stress. A group of proteins, specifically low molecular weight HSPs and HSP70, were up-regulated and expressed in a similar manner in all tissues. Proteomic analysis indicated that the responses of HSP70, CPN-60 beta, and ChsHSP were tissue specific, and this observation was validated by immunoblot analysis. The heat-responsive sHSPs were not induced by other stresses such as cold and hydrogen peroxide. Taken together, these results suggest that to cope with heat stress soybean seedlings operate tissue-specific defenses and adaptive mechanisms, whereas a common defense mechanism associated with the induction of several HSPs was employed in all three tissues. In addition, tissue-specific proteins may play a crucial role in defending each type of tissues against thermal stress.

  3. A Systems Biology Approach to the Coordination of Defensive and Offensive Molecular Mechanisms in the Innate and Adaptive Host-Pathogen Interaction Networks.

    PubMed

    Wu, Chia-Chou; Chen, Bor-Sen

    2016-01-01

    Infected zebrafish coordinates defensive and offensive molecular mechanisms in response to Candida albicans infections, and invasive C. albicans coordinates corresponding molecular mechanisms to interact with the host. However, knowledge of the ensuing infection-activated signaling networks in both host and pathogen and their interspecific crosstalk during the innate and adaptive phases of the infection processes remains incomplete. In the present study, dynamic network modeling, protein interaction databases, and dual transcriptome data from zebrafish and C. albicans during infection were used to infer infection-activated host-pathogen dynamic interaction networks. The consideration of host-pathogen dynamic interaction systems as innate and adaptive loops and subsequent comparisons of inferred innate and adaptive networks indicated previously unrecognized crosstalk between known pathways and suggested roles of immunological memory in the coordination of host defensive and offensive molecular mechanisms to achieve specific and powerful defense against pathogens. Moreover, pathogens enhance intraspecific crosstalk and abrogate host apoptosis to accommodate enhanced host defense mechanisms during the adaptive phase. Accordingly, links between physiological phenomena and changes in the coordination of defensive and offensive molecular mechanisms highlight the importance of host-pathogen molecular interaction networks, and consequent inferences of the host-pathogen relationship could be translated into biomedical applications.

  4. Thermoregulatory defense mechanisms.

    PubMed

    Sessler, Daniel I

    2009-07-01

    Core body temperature is normally tightly regulated by an effective thermoregulatory system. Thermoregulatory control is sometimes impaired by serious illness, but more typically remains intact. The primary autonomic defenses against heat are sweating and active precapillary vasodilation; the primary autonomic defenses against cold are arteriovenous shunt vasoconstriction and shivering. The core temperature triggering each response defines its activation threshold. Temperatures between the sweating and vasoconstriction thresholds define the inter-threshold range. The shivering threshold is usually a full 1 degrees C below the vasoconstriction threshold and is therefore a "last resort" response. Both vasoconstriction and shivering are associated with autonomic and hemodynamic activation; and each response is effective, thus impeding induction of therapeutic hypothermia. It is thus helpful to accompany core cooling with drugs that pharmacologically induce a degree of thermal tolerance. No perfect drug or drug combination has been identified. Anesthetics, for example, induce considerable tolerance, but are rarely suitable. Meperidine-especially in combination with buspirone-is especially effective while provoking only modest toxicity. The combination of buspirone and dexmedetomidine is comparably effective while avoiding the respiratory depression association with opioid administration.

  5. Macrophage defense mechanisms against intracellular bacteria

    PubMed Central

    Weiss, Günter; Schaible, Ulrich E

    2015-01-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. PMID:25703560

  6. Macrophage defense mechanisms against intracellular bacteria.

    PubMed

    Weiss, Günter; Schaible, Ulrich E

    2015-03-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. PMID:25703560

  7. Defense mechanisms development in typical children.

    PubMed

    Tallandini, Maria Anna; Caudek, Corrado

    2010-09-01

    The defense mechanisms (DMs) of 103 nonreferred children ages 47 to 102 months were assessed through dollhouse play. The authors measured the children's temperament (Temperament Assessment Battery for Children-Teacher Form [TABC]) and verbal capacities (Wechsler Preschool and Primary Scale of Intelligence or Wechsler Intelligence Scale for Children). Four main findings were derived: (1) DM use decreased with age with different developmental trajectories; (2) regression, displacement, and reaction formation were more frequent in girls and denial more frequent in boys; (3) the number of DMs used was negatively associated with the TABC Adaptability score and positively with the TABC Approach/Withdrawal score; and (4) children who used rationalization and did not use identification and suppression scored better on verbal capacities.

  8. Protecting the Self: Defense Mechanisms in Action

    ERIC Educational Resources Information Center

    Cramer, Phebe

    2006-01-01

    Integrating theory, research, and practical applications, this book provides a comprehensive examination of defense mechanisms and their role in both normal development and psychopathology. The author describes how children and adults mobilize specific kinds of defenses to maintain their psychological equilibrium and preserve self-esteem,…

  9. The Defense Mechanisms of Coronary Patients.

    ERIC Educational Resources Information Center

    Peglar, Marian; Borgen, Fred H.

    1984-01-01

    Tested 73 male inpatients with coronary heart disease on the Defense Mechanisms Inventory, State-Trait Anxiety Inventory, and a perception of health measure. Subjects were followed for five years. Principalization was discovered to be the most successful and projection the least successful defense. (JAC)

  10. Defense mechanisms: 40 years of empirical research.

    PubMed

    Cramer, Phebe

    2015-01-01

    This article reviews research on defense mechanisms carried out over the past 40 years with children, adolescents, adults, and psychiatric patients. Both experimental and observational studies are included.

  11. Mechanisms of plant defense against insect herbivores.

    PubMed

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ahmad, Tariq; Buhroo, Abdul Ahad; Hussain, Barkat; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2012-10-01

    Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by induced responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be engineered genetically, so that the defensive compounds are constitutively produced in plants against are challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production.

  12. Mechanisms of plant defense against insect herbivores

    PubMed Central

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ahmad, Tariq; Buhroo, Abdul Ahad; Hussain, Barkat; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2012-01-01

    Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by induced responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be engineered genetically, so that the defensive compounds are constitutively produced in plants against are challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production. PMID:22895106

  13. Defense mechanisms and psychological adjustment in childhood.

    PubMed

    Sandstrom, Marlene J; Cramer, Phebe

    2003-08-01

    The association between maturity of defense use and psychological functioning was assessed in a group of 95 elementary school children. Defense mechanisms were measured using a valid and reliable storytelling task, and psychological adjustment was assessed through a combination of parent and self-report questionnaires. Correlational analyses indicated that children who relied on the developmentally immature defense of denial reported higher levels of self-rated social anxiety and depression and received higher ratings of parent-reported internalizing and externalizing behavior problems. However, children who made use of the developmentally mature defense of identification exhibited higher scores on perceived competence in social, academic, conduct, athletic, and global domains. Significantly, there was no relationship between children's use of denial and their level of perceived competence or between children's use of identification and their degree of maladjustment.

  14. Denial Defense Mechanism in Dialyzed Patients

    PubMed Central

    Nowak, Zbigniew; Wańkowicz, Zofia; Laudanski, Krzysztof

    2015-01-01

    Background It is a struggle to identify the most adaptive coping strategies with disease-mediated stress. Here, we hypothesize that intensity of coping strategies, including denial, in patients with end-stage renal disease (ESRD), varies with type of renal replacement therapy (RRT). Material/Methods We enrolled 60 in-center hemodialyzed patients (HD) and 55 patients treated with continuous ambulatory peritoneal dialysis (CAPD). We administered the Coping Inventory with Stressful Situation, Profile of Mood States, and Stroop Anxiety Inventory to measure patient coping strategies in the context of their ESRD. Denial defense mechanism was measured via the IBS-R/ED. The Nottingham Health Profile was used to evaluate self-perceived quality of life. Serum potassium, urea, creatinine, phosphorus, calcium, albumin, and hematocrit were utilized as the measurements of adequacy of dialysis. Results HD patients had higher self-reported intensity of denial mechanism and avoidance-oriented strategies versus CAPD patients. Because a single strategy is almost never employed, we conducted cluster analysis. We identify 3 patterns of coping strategies using cluster analysis. “Repressors” employed denial and avoidance strategies and were predominant in HD. The second cluster consists of subjects employing predominantly task-oriented strategies with equal distribution among dialyzed patients. The third cluster encompassed a small group of patients who shared higher intensity of both denial and task-oriented strategies. Health-related outcome, anxiety, and mood profile were similar across all patients. Conclusions HD patients predominantly used “repressive” strategies. Patients on RRT utilized denial and avoidance-based strategies to achieve satisfactory outcome in terms of perceived quality of life. We conclude that these coping mechanisms that were previously thought to be inferior are beneficial to patient compliance with RRT. PMID:26094792

  15. Antiviral Defense Mechanisms in Honey Bees

    PubMed Central

    Brutscher, Laura M.; Daughenbaugh, Katie F.; Flenniken, Michelle L.

    2015-01-01

    Honey bees are significant pollinators of agricultural crops and other important plant species. High annual losses of honey bee colonies in North America and in some parts of Europe have profound ecological and economic implications. Colony losses have been attributed to multiple factors including RNA viruses, thus understanding bee antiviral defense mechanisms may result in the development of strategies that mitigate colony losses. Honey bee antiviral defense mechanisms include RNA-interference, pathogen-associated molecular pattern (PAMP) triggered signal transduction cascades, and reactive oxygen species generation. However, the relative importance of these and other pathways is largely uncharacterized. Herein we review the current understanding of honey bee antiviral defense mechanisms and suggest important avenues for future investigation. PMID:26273564

  16. Effects of generalized and specialized adaptive defense by shared prey on intra-guild predation.

    PubMed

    Ikegawa, Yusuke; Ezoe, Hideo; Namba, Toshiyuki

    2015-01-01

    Intra-guild predation (IGP), predation on consumers which share common prey with the predators, is an important community module to understand a mechanism for persistence of complex food webs. However, classical theory suggests that persistence of an IGP system is unlikely particularly at high productivity, while empirical data do not support the prediction. Recently, adaptive defense by shared prey has been recognized to enhance coexistence of species and stability of the system. Some organisms having multiple predators in IGP systems employ two types of defenses; generalized defense that is effective against multiple predators and specialized one that is effective against only a specific predator species. We consider an IGP model including shared prey that can use the two types of defenses in combination against the consumer or omnivore. Assuming that the shared prey can change the allocation of defensive effort to increase its fitness, we show that the joint use of two types of adaptive defenses promotes three species coexistence and enhances stability of the IGP system when the specialized defense is more effective than the generalized one. When the system is unstable, a variety of oscillations appear and both the population densities and defensive efforts or only the population densities oscillate. Joint use of defenses against the consumer tends to increase the equilibrium population density of the shared prey with the defense efficiencies. In contrast, efficient generalized and specialized defenses against the omnivore often decrease the prey population. Consequently, adaptive defense by shared prey may not necessarily heighten the population size of the defender but sometimes increases densities of both the attackers and defender in IGP systems.

  17. Defense Mechanisms: Discussions and Bibliographies; General or Multiple, and Specific.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    This publication considers some Freudian ego mechanisms. The first discussion and bibliography concerns defense mechanisms, in general or in multiple; after which, the discussions and bibliographies concern specific defense mechanisms: denial; displacement, substitution, sublimation; fixation; identification, introjection, incorporation,…

  18. Pulmonary defense mechanisms against opportunistic fungal pathogens.

    PubMed

    Waldorf, A R

    1989-01-01

    Though of critical importance, nonimmune host defense mechanisms against aspergillosis and mucormycosis are not completely understood. Prevention of these infections presumably requires control of either spore germination and/or hyphal growth by the host. The data suggest that the host provides an important barrier to infection by control of spore or conidia germination, the critical step involving conversion of the fungus to its tissue-invasive form. The mechanisms of host defense against A. fumigatus are not strictly dependent on inhibition of conidia germination. Rather, pulmonary defense against Aspergillus appears to depend to a greater degree on early killing of fungal conidia by alveolar macrophages. In contrast, prevention of mucormycosis appears to require inhibition of fungal spore germination by the bronchoalveolar macrophage, thereby preventing conversion of the fungus to its hyphal form, although resident bronchoalveolar macrophages are unable to kill R. oryzae spores. Thus, host pulmonary defenses to Rhizopus and Aspergillus vary, even in normal animals. The tissue-invasive hyphal forms of the fungi which cause aspergillosis and mucormycosis are too large to be ingested by phagocytic cells. Although macrophages and monocytes can damage hyphae, the bulk of this role appears to fall upon the neutrophil. However, antihyphal mechanisms of neutrophils may not necessarily be identical for all types of hyphae. Moreover, interactions of several potential oxidative and nonoxidative antihyphal mechanisms may define the host's ability to limit fungal infections. In individuals where concentrations of oxidative or nonoxidative substances are limiting or suboptimal, interactions of mechanisms may be required for antihyphal activity, and studies of these interactions are important to gain better knowledge of the defense mechanisms against opportunistic mycoses in the intact host. In summary, at least two distinct lines of defense against Aspergillus and Rhizopus

  19. Rock mechanics contributions from defense programs

    SciTech Connect

    Heuze, F.E.

    1992-02-01

    An attempt is made at illustrating the many contributions to rock mechanics from US defense programs, over the past 30-plus years. Large advances have been achieved in the technology-base area covering instrumentation, material properties, physical modeling, constitutive relations and numerical simulations. In the applications field, much progress has been made in understanding and being able to predict rock mass behavior related to underground explosions, cratering, projectile penetration, and defense nuclear waste storage. All these activities stand on their own merit as benefits to national security. But their impact is even broader, because they have found widespread applications in the non-defense sector; to name a few: the prediction of the response of underground structures to major earthquakes, the physics of the earth`s interior at great depths, instrumentation for monitoring mine blasting, thermo-mechanical instrumentation useful for civilian nuclear waste repositories, dynamic properties of earthquake faults, and transient large-strain numerical modeling of geological processes, such as diapirism. There is not pretense that this summary is exhaustive. It is meant to highlight success stories representative of DOE and DOD geotechnical activities, and to point to remaining challenges.

  20. Prevalence and Mechanisms of Dynamic Chemical Defenses in Tropical Sponges

    PubMed Central

    Rohde, Sven; Nietzer, Samuel; Schupp, Peter J.

    2015-01-01

    Sponges and other sessile invertebrates are lacking behavioural escape or defense mechanisms and rely therefore on morphological or chemical defenses. Studies from terrestrial systems and marine algae demonstrated facultative defenses like induction and activation to be common, suggesting that sessile marine organisms also evolved mechanisms to increase the efficiency of their chemical defense. However, inducible defenses in sponges have not been investigated so far and studies on activated defenses are rare. We investigated whether tropical sponge species induce defenses in response to artificial predation and whether wounding triggers defense activation. Additionally, we tested if these mechanisms are also used to boost antimicrobial activity to avoid bacterial infection. Laboratory experiments with eight pacific sponge species showed that 87% of the tested species were chemically defended. Two species, Stylissa massa and Melophlus sarasinorum, induced defenses in response to simulated predation, which is the first demonstration of induced antipredatory defenses in marine sponges. One species, M. sarasinorum, also showed activated defense in response to wounding. Interestingly, 50% of the tested sponge species demonstrated induced antimicrobial defense. Simulated predation increased the antimicrobial defenses in Aplysinella sp., Cacospongia sp., M. sarasinorum, and S. massa. Our results suggest that wounding selects for induced antimicrobial defenses to protect sponges from pathogens that could otherwise invade the sponge tissue via feeding scars. PMID:26154741

  1. Prevalence and Mechanisms of Dynamic Chemical Defenses in Tropical Sponges.

    PubMed

    Rohde, Sven; Nietzer, Samuel; Schupp, Peter J

    2015-01-01

    Sponges and other sessile invertebrates are lacking behavioural escape or defense mechanisms and rely therefore on morphological or chemical defenses. Studies from terrestrial systems and marine algae demonstrated facultative defenses like induction and activation to be common, suggesting that sessile marine organisms also evolved mechanisms to increase the efficiency of their chemical defense. However, inducible defenses in sponges have not been investigated so far and studies on activated defenses are rare. We investigated whether tropical sponge species induce defenses in response to artificial predation and whether wounding triggers defense activation. Additionally, we tested if these mechanisms are also used to boost antimicrobial activity to avoid bacterial infection. Laboratory experiments with eight pacific sponge species showed that 87% of the tested species were chemically defended. Two species, Stylissa massa and Melophlus sarasinorum, induced defenses in response to simulated predation, which is the first demonstration of induced antipredatory defenses in marine sponges. One species, M. sarasinorum, also showed activated defense in response to wounding. Interestingly, 50% of the tested sponge species demonstrated induced antimicrobial defense. Simulated predation increased the antimicrobial defenses in Aplysinella sp., Cacospongia sp., M. sarasinorum, and S. massa. Our results suggest that wounding selects for induced antimicrobial defenses to protect sponges from pathogens that could otherwise invade the sponge tissue via feeding scars.

  2. Validity of Self-Report Measures of Defense Mechanisms

    PubMed

    Mehlman; Slane

    1994-06-01

    The Life Style Index (LSI), the Defense Style Questionnaire (DSQ), the Defense Mechanisms Inventory (DMI), and the FIRO Coping Operations Preferences Enquiry (FIRO) were administered to 187 undergraduates in order to determine convergent and discriminant validity of self-report measures of defense mechanisms. A correlational analysis of the four scales resulted in low correlations among subscales measuring similar defense mechanisms. A factor analysis produced factors based on particular scales rather than identical or similar constructs. Results suggest that self-report measures may not be an effective method for assessing various ego defense strategies.

  3. Strategic Defense Initiative Organization adaptive structures program overview

    NASA Astrophysics Data System (ADS)

    Obal, Michael; Sater, Janet M.

    In the currently envisioned architecture none of the Strategic Defense System (SDS) elements to be deployed will receive scheduled maintenance. Assessments of performance capability due to changes caused by the uncertain effects of environments will be difficult, at best. In addition, the system will have limited ability to adjust in order to maintain its required performance levels. The Materials and Structures Office of the Strategic Defense Initiative Organization (SDIO) has begun to address solutions to these potential difficulties via an adaptive structures technology program that combines health and environment monitoring with static and dynamic structural control. Conceivable system benefits include improved target tracking and hit-to-kill performance, on-orbit system health monitoring and reporting, and threat attack warning and assessment.

  4. Change in coping and defense mechanisms across adulthood: longitudinal findings in a European American sample.

    PubMed

    Diehl, Manfred; Chui, Helena; Hay, Elizabeth L; Lumley, Mark A; Grühn, Daniel; Labouvie-Vief, Gisela

    2014-02-01

    This study examined longitudinal changes in coping and defense mechanisms in an age- and gender-stratified sample of 392 European American adults. Nonlinear age-related changes were found for the coping mechanisms of sublimation and suppression and the defense mechanisms of intellectualization, doubt, displacement, and regression. The change trajectories for sublimation and suppression showed that their use increased from adolescence to late middle age and early old age and remained mostly stable into late old age. The change trajectory for intellectualization showed that the use of this defense mechanism increased from adolescence to middle age, remained stable until late midlife, and started to decline thereafter. The defense mechanisms of doubt, displacement, and regression showed decreases from adolescence until early old age, with increases occurring again after the age of 65. Linear age-related decreases were found for the coping mechanism of ego regression and the defense mechanisms of isolation and rationalization. Gender and socioeconomic status were associated with the mean levels of several coping and defense mechanisms but did not moderate age-related changes. Increases in ego level were associated with increased use of the defense mechanism intellectualization and decreased use of the defense mechanisms of doubt and displacement. Overall, these findings in a European American sample suggest that most individuals showed development in the direction of more adaptive and less maladaptive coping and defense strategies from adolescence until late middle age or early old age. However, in late old age this development was reversed, presenting potential challenges to the adaptive capacity of older adults.

  5. Defense mechanisms in adolescent conduct disorder and adjustment reaction.

    PubMed

    Cramer, Phebe; Kelly, Francis D

    2004-02-01

    The use of defense mechanisms by male and female adolescents with a diagnosis of conduct disorder was compared with the defense use of adolescents with a diagnosis of adjustment reaction. Because conduct disorder has been shown to be associated with a developmental lag in several areas of psychological functioning, we expected that these adolescents would show immaturity in the use of defenses. This expectation was confirmed. As compared with adjustment reaction, conduct disordered youths were more likely to use the immature defense of denial and less likely to use the mature defense of identification.

  6. Ego Defenses and Reaction to Stress: A Validation Study of the Defense Mechanisms Inventory

    ERIC Educational Resources Information Center

    Gleser, Goldine C.; Sacks, Marilyn

    1973-01-01

    This study investigated the relationship between scores on the Defense Mechanisms Inventory and reaction to an experimental conflict situation in which Ss (85 undergraduate college students) were led to believe that their performance was deficient on a new test of scholastic ability. The pattern of defenses predicted residual posttest estimates of…

  7. Adversity Quotient and Defense Mechanism of Secondary School Students

    ERIC Educational Resources Information Center

    Nikam, Vibhawari B.; Uplane, Megha M.

    2013-01-01

    The present study was conducted to explore the relationship between Adversity Quotient (AQ) and Defense Mechanism (DM) of secondary school students. The aim of the study was to ascertain relationship between Adversity Quotient and Defense mechanism i. e. Turning against object (TAO), Projection (PRO), Turning against self (TAS), Principalisation…

  8. Defense mechanisms in schizotypal, borderline, antisocial, and narcissistic personality disorders.

    PubMed

    Perry, J Christopher; Presniak, Michelle D; Olson, Trevor R

    2013-01-01

    Numerous authors have theorized that defense mechanisms play a role in personality disorders. We reviewed theoretical writings and empirical studies about defenses in schizotypal, borderline, antisocial, and narcissistic personality disorders, developing hypotheses about these differential relationships. We then examined these hypotheses using dynamic interview data rated for defenses in a study of participants (n = 107) diagnosed with these four personality disorder types. Overall, the prevalence of immature defenses was substantial, and all four disorders fit within the broad borderline personality organization construct. Defenses predicted the most variance in borderline and the least variance in schizotypal personality disorder, suggesting that dynamic factors played the largest role in borderline and the least in schizotypal personality. Central to borderline personality were strong associations with major image-distorting defenses, primarily splitting of self and other's images, and the hysterical level defenses, dissociation and repression. Narcissistic and antisocial personality disorders shared minor image-distorting defenses, such as omnipotence or devaluation, while narcissistic also used splitting of self-images and antisocial used disavowal defenses like denial. Overall, differential relationships between specific defenses and personality disorder types were largely consistent with the literature, and consistent with the importance that the treatment literature ascribes to working with defenses.

  9. Study of Defensive Methods and Mechanisms in Developmental, Emotional (Internalization), and Disruptive Behavior (Externalization) Disorders

    PubMed Central

    Jamilian, H. R.; Zamani, N.; Darvishi, M.; Khansari, M. R.

    2014-01-01

    We need to find a way for adaptation with inherent unpleasantness of being human condition and conflicts that it caused, as we did not fail. Methods that we used for adaptation are named defense. This research have performed with the aim of study and compare defensive mechanisms and methods of Developmental, Emotional (Internalization), and Disruptive behavior (Externalization) disorders. Method, sample of this research included 390 family that are by available sampling method are selected. Tools of research were structured clinical interview of forth cognitive and statistical guide of psychopathic disorders for axis I and the way used for assess defensive mechanisms is defensive method 40 question’s questionnaires of Andrews (1993). The data are compared by statistical methods comparison of averages and one way variance analysis and HSD tests and results show that undeveloped defensive mechanisms in by developmental disorder family(25.2± 3.7) mean and standard deviation, it is most used mechanism and in disruptive behavior disorder family by (11.2 ±1.9) mean and standard deviation is used least mechanism and in developed mechanism of emotional disorder family by (7.8 ± 3.1) mean and standard deviation is most used mechanism and in developmental disorder family by (4.3 ±1.5) mean and standard deviation is least mechanism in neuroticism patient, social phobia affected emotional disorder family (15.6±2.6) and disruptive behavior disorder family have least mean and standard deviation(9.2±1.7) (p< 0.005). Recent research shows significant of study defensive mechanism in psychopathic family of disorder children that affecting on the way of life of persons and interpersonal and intrapersonal relations and method of solving problem in family of them in life, so defensive mechanisms require more attention. PMID:25363187

  10. Girls' use of defense mechanisms following peer rejection.

    PubMed

    Sandstrom, Marlene J; Cramer, Phebe

    2003-08-01

    This study explores the relation between girls' social adjustment and their use of defense mechanisms. We recruited girls representing four sociometric status classifications (rejected, neglected, average, and popular), and assessed their use of defense mechanisms both before and after encountering a peer rejection experience in the laboratory. We hypothesized that increasing degrees of social maladjustment would be associated with higher levels of defense use, particularly after encountering a rejection experience. Our results supported these hypotheses. There was a significant negative relationship between social adjustment and defense use, both prior to and immediately following the rejection experience. Categorical analyses revealed that rejected and neglected girls used more defenses following the rejection experience than did popular and average girls.

  11. A content validity study of the defense mechanism inventory.

    PubMed

    Blacha, M D; Fancher, R E

    1977-08-01

    The content validity of the Defense Mechanism Inventory was tested by 20 raters who evaluated each item in terms of which 15 defenses and three ego threats it represented. Items purportedly measuring the global defense categories of principalization, turning against self, and reversal, achieved relatively high rater agreement (over 70%) while projection and turning against Object fared poorly (29% and 39% respectively). Differential content validity was found in the levels and areas of the Inventory, indicating that the context in which items appear affect their representativeness of defensive behaviors. The individual defense mechanisms were disproportionately represented by the Inventory. Ratings suggested that aggressiveness was the major ego threat being measured by the items. Most of the problems appear correctable through rewriting many of the items.

  12. Defense mechanisms development in children, adolescents, and late adolescents.

    PubMed

    Porcerelli, J H; Thomas, S; Hibbard, S; Cogan, R

    1998-12-01

    To replicate and extend Cramer's (1987) original cross-sectional study concerning the development of defense mechanisms, the Thematic Apperception Test responses of 148 students in Grades 2, 5, 8, 11, and college freshmen were collected and scored for denial, projection, and identification using Cramer's Defense Mechanisms Manual (1991). Our results supported the notion that the relative use of denial and projection decreases and identification increases as a function of grade level. The findings provide additional support for the psychoanalytic view (Freud, 1966) of an ontogenetic developmental line of defense.

  13. Polyphenol oxidase as a biochemical seed defense mechanism

    PubMed Central

    Fuerst, E. Patrick; Okubara, Patricia A.; Anderson, James V.; Morris, Craig F.

    2014-01-01

    Seed dormancy and resistance to decay are fundamental survival strategies, which allow a population of seeds to germinate over long periods of time. Seeds have physical, chemical, and biological defense mechanisms that protect their food reserves from decay-inducing organisms and herbivores. Here, we hypothesize that seeds also possess enzyme-based biochemical defenses, based on induction of the plant defense enzyme, polyphenol oxidase (PPO), when wild oat (Avena fatua L.) caryopses and seeds were challenged with seed-decaying Fusarium fungi. These studies suggest that dormant seeds are capable of mounting a defense response to pathogens. The pathogen-induced PPO activity from wild oat was attributed to a soluble isoform of the enzyme that appeared to result, at least in part, from proteolytic activation of a latent PPO isoform. PPO activity was also induced in wild oat hulls (lemma and palea), non-living tissues that cover and protect the caryopsis. These results are consistent with the hypothesis that seeds possess inducible enzyme-based biochemical defenses arrayed on the exterior of seeds and these defenses represent a fundamental mechanism of seed survival and longevity in the soil. Enzyme-based biochemical defenses may have broader implications since they may apply to other defense enzymes as well as to a diversity of plant species and ecosystems. PMID:25540647

  14. 75 FR 34988 - Federal Advisory Committee; Defense Science Board 2010 Summer Study on Enhancing Adaptability of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... of the Secretary Federal Advisory Committee; Defense Science Board 2010 Summer Study on Enhancing... meeting. SUMMARY: The Defense Science Board 2010 Summer Study on Enhancing Adaptability of our Military... of adaptation, both commercial and non-commercial, and what made them successful and...

  15. [Host defense mechanisms against Salmonella infection].

    PubMed

    Mizuno, Yumi

    2004-12-01

    Salmonella is one of the gram negative intracellular pathogens. The immune response to Salmonella includes innate immunity and adaptive immunity. The intestinal epithelium, neutrophil, macrophage, dendritic cell, NK cell, NK T cell and gammadelta T cell take important part in former process, and antigen specific T cell and B cell take part in the later process. Macrophages and dendritic cells increase in number early after Salmonella infection and produce variety of cytokines. Especially, IL-12, IL-15 and IL-18 play important roles in protection against Salmonella infection, proliferation of NK cell, NKT cell and gammadelta T cell, producing IFN-gamma, in addition, IL-12 and IL-18 induce IFN-gamma production by Th1 cells and adaptive immune response.

  16. [Psychometric assessment of defense mechanisms: correlation between questionnaire and expert rating. Initial study of validity].

    PubMed

    Reister, G; Fellhauer, R F; Franz, M; Wirth, T; Schellberg, D; Schepank, H; Tress, W

    1993-01-01

    Within the limits of an epidemiological longitudinal field survey on prevalence and course of psychogenic disorders a high-risk-population suffering from medical psychogenic impairment was investigated. The study was conducted in order to verify an etiological multi-level-model of psychogenic disorders in relation to the socialempiric variables "critical life events" and "social support" as well as the depth psychological oriented construct "personality". Besides other instruments a self rating scale based on Vallant's hierarchical model of defense, i.e. the german adaptation of the DSQ (Defense Style Questionnaire) of Bond and coworkers, was used for the accurate measurement of relevant personality parameters. Although defense processes predominantly work unconscious, manifestations of defense mechanisms could be measured indirectly by means of the rating scale. Its essential dimensions separated clinical patients from a group of healthy controls. Furthermore an immature organisation of defense was found to be related to psychogenic impairment. Concerning self- and expert-rating a significant correlation between "immature defense" and the defense mechanisms "schizoid phantasy", "projection" and "acting out" was proved.

  17. Current concepts on pulmonary host defense mechanisms in children.

    PubMed

    Wilmott, R W; Khurana-Hershey, G; Stark, J M

    2000-06-01

    The respiratory tract is exposed continuously to noxious agents, microbial organisms, particles, and allergens. It has therefore evolved both innate and specific defense mechanisms. The innate host defense mechanisms include components such as collectins, beta-defensins, lactoferrin, and complement, all of which have an important role in modulating the immune response. Immune protection of the lungs by specific antibody is reviewed. The airways are protected by alveolar macrophages, neutrophils, and lymphocytes, and their origins, regulation, functions, and antimicrobial activity are summarized. Antimicrobial peptides and immune-modulating peptides are likely to have a significant therapeutic role for infection and inflammation in the respiratory tract.

  18. Grooming Behavior as a Mechanism of Insect Disease Defense

    PubMed Central

    Zhukovskaya, Marianna; Yanagawa, Aya; Forschler, Brian T.

    2013-01-01

    Grooming is a well-recognized, multipurpose, behavior in arthropods and vertebrates. In this paper, we review the literature to highlight the physical function, neurophysiological mechanisms, and role that grooming plays in insect defense against pathogenic infection. The intricate relationships between the physical, neurological and immunological mechanisms of grooming are discussed to illustrate the importance of this behavior when examining the ecology of insect-pathogen interactions. PMID:26462526

  19. Evolution of adaptation mechanisms: Adaptation energy, stress, and oscillating death.

    PubMed

    Gorban, Alexander N; Tyukina, Tatiana A; Smirnova, Elena V; Pokidysheva, Lyudmila I

    2016-09-21

    In 1938, Selye proposed the notion of adaptation energy and published 'Experimental evidence supporting the conception of adaptation energy.' Adaptation of an animal to different factors appears as the spending of one resource. Adaptation energy is a hypothetical extensive quantity spent for adaptation. This term causes much debate when one takes it literally, as a physical quantity, i.e. a sort of energy. The controversial points of view impede the systematic use of the notion of adaptation energy despite experimental evidence. Nevertheless, the response to many harmful factors often has general non-specific form and we suggest that the mechanisms of physiological adaptation admit a very general and nonspecific description. We aim to demonstrate that Selye׳s adaptation energy is the cornerstone of the top-down approach to modelling of non-specific adaptation processes. We analyze Selye׳s axioms of adaptation energy together with Goldstone׳s modifications and propose a series of models for interpretation of these axioms. Adaptation energy is considered as an internal coordinate on the 'dominant path' in the model of adaptation. The phenomena of 'oscillating death' and 'oscillating remission' are predicted on the base of the dynamical models of adaptation. Natural selection plays a key role in the evolution of mechanisms of physiological adaptation. We use the fitness optimization approach to study of the distribution of resources for neutralization of harmful factors, during adaptation to a multifactor environment, and analyze the optimal strategies for different systems of factors.

  20. The Venturia Apple Pathosystem: Pathogenicity Mechanisms and Plant Defense Responses

    PubMed Central

    Jha, Gopaljee; Thakur, Karnika; Thakur, Priyanka

    2009-01-01

    Venturia inaequalis is the causal agent of apple scab, a devastating disease of apple. We outline several unique features of this pathogen which are useful for molecular genetics studies intended to understand plant-pathogen interactions. The pathogenicity mechanisms of the pathogen and overview of apple defense responses, monogenic and polygenic resistance, and their utilization in scab resistance breeding programs are also reviewed. PMID:20150969

  1. Molecular mechanisms of temperature adaptation.

    PubMed

    Bagriantsev, Sviatoslav N; Gracheva, Elena O

    2015-08-15

    Thermal perception is a fundamental physiological process pertaining to the vast majority of organisms. In vertebrates, environmental temperature is detected by the primary afferents of the somatosensory neurons in the skin, which express a 'choir' of ion channels tuned to detect particular temperatures. Nearly two decades of research have revealed a number of receptor ion channels that mediate the perception of several temperature ranges, but most still remain molecularly orphaned. Yet even within this well-researched realm, most of our knowledge largely pertains to two closely related species of rodents, mice and rats. While these are standard biomedical research models, mice and rats provide a limited perspective to elucidate the general principles that drive somatosensory evolution. In recent years, significant advances have been made in understanding the molecular mechanism of temperature adaptation in evolutionarily distant vertebrates and in organisms with acute thermal sensitivity. These studies have revealed the remarkable versatility of the somatosensory system and highlighted adaptations at the molecular level, which often include changes in biophysical properties of ion channels from the transient receptor potential family. Exploiting non-standard animal models has the potential to provide unexpected insights into general principles of thermosensation and thermoregulation, unachievable using the rodent model alone.

  2. Molecular mechanisms of temperature adaptation

    PubMed Central

    Bagriantsev, Sviatoslav N; Gracheva, Elena O

    2015-01-01

    Thermal perception is a fundamental physiological process pertaining to the vast majority of organisms. In vertebrates, environmental temperature is detected by the primary afferents of the somatosensory neurons in the skin, which express a ‘choir’ of ion channels tuned to detect particular temperatures. Nearly two decades of research have revealed a number of receptor ion channels that mediate the perception of several temperature ranges, but most still remain molecularly orphaned. Yet even within this well-researched realm, most of our knowledge largely pertains to two closely related species of rodents, mice and rats. While these are standard biomedical research models, mice and rats provide a limited perspective to elucidate the general principles that drive somatosensory evolution. In recent years, significant advances have been made in understanding the molecular mechanism of temperature adaptation in evolutionarily distant vertebrates and in organisms with acute thermal sensitivity. These studies have revealed the remarkable versatility of the somatosensory system and highlighted adaptations at the molecular level, which often include changes in biophysical properties of ion channels from the transient receptor potential family. Exploiting non-standard animal models has the potential to provide unexpected insights into general principles of thermosensation and thermoregulation, unachievable using the rodent model alone. PMID:25433072

  3. Molecular mechanisms of temperature adaptation.

    PubMed

    Bagriantsev, Sviatoslav N; Gracheva, Elena O

    2015-08-15

    Thermal perception is a fundamental physiological process pertaining to the vast majority of organisms. In vertebrates, environmental temperature is detected by the primary afferents of the somatosensory neurons in the skin, which express a 'choir' of ion channels tuned to detect particular temperatures. Nearly two decades of research have revealed a number of receptor ion channels that mediate the perception of several temperature ranges, but most still remain molecularly orphaned. Yet even within this well-researched realm, most of our knowledge largely pertains to two closely related species of rodents, mice and rats. While these are standard biomedical research models, mice and rats provide a limited perspective to elucidate the general principles that drive somatosensory evolution. In recent years, significant advances have been made in understanding the molecular mechanism of temperature adaptation in evolutionarily distant vertebrates and in organisms with acute thermal sensitivity. These studies have revealed the remarkable versatility of the somatosensory system and highlighted adaptations at the molecular level, which often include changes in biophysical properties of ion channels from the transient receptor potential family. Exploiting non-standard animal models has the potential to provide unexpected insights into general principles of thermosensation and thermoregulation, unachievable using the rodent model alone. PMID:25433072

  4. Longitudinal study of defense mechanisms: late childhood to late adolescence.

    PubMed

    Cramer, Phebe

    2007-02-01

    Based on longitudinal data from the Institute of Human Development Intergenerational Study, the use and change in defense mechanisms of more than 150 individuals, as assessed from TAT stories, was studied across ages 11, 12, and 18. The findings of this study, based on an earlier generation, were generally consistent with cross-sectional findings from current samples, showing that the defenses of projection and identification were used more frequently than denial at all three ages and that the use of projection and identification increased from early to late adolescence. However, unlike current findings, the 18-year-olds did not show greater use of identification than of projection, perhaps due to IQ differences between this community sample and the samples of more recent studies.

  5. The strawberry plant defense mechanism: a molecular review.

    PubMed

    Amil-Ruiz, Francisco; Blanco-Portales, Rosario; Muñoz-Blanco, Juan; Caballero, José L

    2011-11-01

    Strawberry, a small fruit crop of great importance throughout the world, has been considered a model plant system for Rosaceae, and is susceptible to a large variety of phytopathogenic organisms. Most components and mechanisms of the strawberry defense network remain poorly understood. However, from current knowledge, it seems clear that the ability of a strawberry plant to respond efficiently to pathogens relies first on the physiological status of injured tissue (pre-formed mechanisms of defense) and secondly on the general ability to recognize and identify the invaders by surface plant receptors, followed by a broad range of induced mechanisms, which include cell wall reinforcement, production of reactive oxygen species, phytoalexin generation and pathogenesis-related protein accumulation. Dissection of these physiological responses at a molecular level will provide valuable information to improve future breeding strategies for new strawberry varieties and to engineer strawberry plants for durable and broad-spectrum disease resistance. In turn, this will lead to a reduction in use of chemicals and in environmental risks. Advances in the understanding of the molecular interplay between plant (mainly those considered model systems) and various classes of microbial pathogens have been made in the last two decades. However, major progress in the genetics and molecular biology of strawberry is still needed to uncover fully the way in which this elaborate plant innate immune system works. These fundamental insights will provide a conceptual framework for rational human intervention through new strawberry research approaches. In this review, we will provide a comprehensive overview and discuss recent advances in molecular research on strawberry defense mechanisms against pathogens.

  6. Respiratory infections may reflect deficiencies in host defense mechanisms.

    PubMed

    Reynolds, H Y

    1985-02-01

    Serious respiratory tract infections are rare in the healthy individual and most of the nuisance morbidity that occurs results from nasopharyngeal viral infections that many people get once or twice a year. The economic impact from these upper respiratory tract infections is appreciable, however, in terms of absenteeism from school or work, but unfortunately there is little that can be done to ward them off in a practical way. Pneumonia is an infrequent lifetime experience for most non-smoking adults and when it occurs, unusual circumstances may pertain--a particularly virulent microorganism is in circulation, or perhaps one has been exposed to a newly recognized germ, such as has occurred with Legionella species in the past 8 years or so. What protects us the great majority of the time is a very effective network of respiratory tract host defenses. These include many mechanical and anatomical barrier mechanisms concentrated in nose and throat; mucociliary clearance, coughing and mucosal immunoglobulins in the conducting airways and in the air-exchange region of the alveolar structures, phagocytes, opsonins, complement, surfactant and many other factors combine to clear infectious agents. The ability to mount an inflammatory response in the alveoli may represent the maximal and ultimate expression of local host defense. In some way these host defenses are combating constantly the influx of micro-organisms, usually inhaled or aspirated into the airways, that try to gain a foothold on the mucosal surface and colonize it. But many general changes in overall health such as debility, poor nutrition, metabolic derangements, bone marrow suppression and perhaps aging promote abnormal microbial colonization and undermine the body's defenses that try to cope with the situation. It is a dynamic struggle. The departure from normal respiratory health may not be obvious immediately to the patient or to the physician and repeated episodes of infection or persisting symptoms of

  7. Defense Mechanisms in Adolescence as Predictors of Adult Personality Disorders.

    PubMed

    Strandholm, Thea; Kiviruusu, Olli; Karlsson, Linnea; Miettunen, Jouko; Marttunen, Mauri

    2016-05-01

    Our study examines whether defense styles and separate defenses in depressed adolescent outpatients predict adult personality disorders (PDs). We obtained data from consecutive adolescent outpatients who participated in the Adolescent Depression Study at baseline and at the 8-year follow-up (N = 140). Defense styles were divided into mature, neurotic, image-distorting, and immature and a secondary set of analyses were made with separate defenses as predictors of a PD diagnosis. Neurotic, image-distorting, and immature defense styles in adolescence were associated with adulthood PDs. Neurotic defense style associated with cluster B diagnosis and image-distorting defense style associated with cluster A diagnosis. Separate defenses of displacement, isolation, and reaction formation were independent predictors of adult PD diagnosis even after adjusting for PD diagnosis in adolescence. Defense styles and separate defenses predict later PDs and could be used in the focusing of treatment interventions for adolescents.

  8. Drought Adaptation Mechanisms Should Guide Experimental Design.

    PubMed

    Gilbert, Matthew E; Medina, Viviana

    2016-08-01

    The mechanism, or hypothesis, of how a plant might be adapted to drought should strongly influence experimental design. For instance, an experiment testing for water conservation should be distinct from a damage-tolerance evaluation. We define here four new, general mechanisms for plant adaptation to drought such that experiments can be more easily designed based upon the definitions. A series of experimental methods are suggested together with appropriate physiological measurements related to the drought adaptation mechanisms. The suggestion is made that the experimental manipulation should match the rate, length, and severity of soil water deficit (SWD) necessary to test the hypothesized type of drought adaptation mechanism. PMID:27090148

  9. Monocular and binocular mechanisms mediating flicker adaptation.

    PubMed

    Zhuang, Xiaohua; Shevell, Steven K

    2015-12-01

    Flicker adaptation reduces subsequent temporal contrast sensitivity. Recent studies show that this adaptation likely results from neural changes in the magnocellular visual pathway, but whether this adaptation occurs at a monocular or a binocular level, or both, is unclear. Here, two experiments address this question. The first experiment exploits the observation that flicker adaptation is stronger at higher than lower temporal frequencies. Observers' two eyes adapted to 3Hz flicker with an incremental pulse at 1/4 duty cycle, either in-phase or out-of-phase in the two eyes. At the binocular level, the flicker rate was 6Hz in the out-of-phase condition if the two eyes' pulse trains sum. Similar sensitivity reduction was found in both phase conditions, as expected for independent monocular adapting mechanisms. The second experiment tested for interocular transfer of adaptation between eyes. Results showed that (1) flicker adaptation was strongest with adapting and test fields in only the same eye, (2) adaptation can be partially transferred interocularly with adaptation in only the opposite eye, and (3) adaptation was weakened when both eyes were adapted simultaneously at different contrasts, compared to test-eye adaptation alone. Taken together, the findings are consistent with mechanisms of flicker adaptation at both the monocular and binocular level. PMID:26505684

  10. Drosophila Adaptation to Viral Infection through Defensive Symbiont Evolution

    PubMed Central

    Faria, Vitor G.; Magalhães, Sara; Paulo, Tânia F.; Nolte, Viola; Schlötterer, Christian

    2016-01-01

    Microbial symbionts can modulate host interactions with biotic and abiotic factors. Such interactions may affect the evolutionary trajectories of both host and symbiont. Wolbachia protects Drosophila melanogaster against several viral infections and the strength of the protection varies between variants of this endosymbiont. Since Wolbachia is maternally transmitted, its fitness depends on the fitness of its host. Therefore, Wolbachia populations may be under selection when Drosophila is subjected to viral infection. Here we show that in D. melanogaster populations selected for increased survival upon infection with Drosophila C virus there is a strong selection coefficient for specific Wolbachia variants, leading to their fixation. Flies carrying these selected Wolbachia variants have higher survival and fertility upon viral infection when compared to flies with the other variants. These findings demonstrate how the interaction of a host with pathogens shapes the genetic composition of symbiont populations. Furthermore, host adaptation can result from the evolution of its symbionts, with host and symbiont functioning as a single evolutionary unit. PMID:27684942

  11. Defense High-Level Waste Leaching Mechanisms Program. Final report

    SciTech Connect

    Mendel, J.E.

    1984-08-01

    The Defense High-Level Waste Leaching Mechanisms Program brought six major US laboratories together for three years of cooperative research. The participants reached a consensus that solubility of the leached glass species, particularly solubility in the altered surface layer, is the dominant factor controlling the leaching behavior of defense waste glass in a system in which the flow of leachant is constrained, as it will be in a deep geologic repository. Also, once the surface of waste glass is contacted by ground water, the kinetics of establishing solubility control are relatively rapid. The concentrations of leached species reach saturation, or steady-state concentrations, within a few months to a year at 70 to 90/sup 0/C. Thus, reaction kinetics, which were the main subject of earlier leaching mechanisms studies, are now shown to assume much less importance. The dominance of solubility means that the leach rate is, in fact, directly proportional to ground water flow rate. Doubling the flow rate doubles the effective leach rate. This relationship is expected to obtain in most, if not all, repository situations.

  12. Biochemical defense strategies in sterilized seedlings of Nymphoides peltatum adapted to lead stress.

    PubMed

    Qiao, Xuqiang; Shi, Guoxin; Yang, Xiaoke; Zheng, Zhenzhen; Xu, Xiaoying; Yang, Haiyan

    2014-01-01

    In order to study potential antioxidant defense mechanisms, the effects of increasing concentrations of lead (Pb) on polyamines (PAs), various thiols, vitamins C and E, and proline contents in sterilized seedlings of Nymphoides peltata (S.G. mel.) Kuntze were investigated after 5 days of exposure. The levels of total putrescine (Put), spermidine (Spd), and spermine (Spm) decreased significantly, while the ratio of (Spd + Spm)/Put first increased but then declined as the concentration of Pb increased. The trends for free, perchloric acid soluble-conjugated (PS-conjugated), and perchloric acid insoluble-bound (PIS-bound) PAs were similar to the trend seen for total PAs. Moreover, reduced glutathione (GSH), nonprotein thiols (NP-SH), phytochelatins (PCs), and vitamin C were induced at high Pb concentrations. No significant change was observed in vitamin E. An initial decline in proline content was followed by an increase as the Pb concentration rose. The reduced level of Put and elevated contents of GSH, NP-SH, PCs, vitamin C, and proline were found to be associated with antioxidant efficiency, which supports the hypothesis that they could play a significant role in the adaptation mechanisms of N. peltatum under Pb stress.

  13. A complex of genes involved in adaptation of Leptinotarsa decemlineata larvae to induced potato defense.

    PubMed

    Petek, Marko; Turnšek, Neža; Gašparič, Meti Buh; Novak, Maruša Pompe; Gruden, Kristina; Slapar, Nina; Popovič, Tatjana; Štrukelj, Borut; Gruden, Kristina; Štrukelj, Borut; Jongsma, Maarten A

    2012-03-01

    The Colorado potato beetle (Leptinotarsa decemlineata) is the most important pest of potato in many areas of the world. One of the main reasons for its success lies in the ability of its larvae to counteract plant defense compounds. Larvae adapt to protease inhibitors (PIs) produced in potato leaves through substitution of inhibitor-sensitive digestive cysteine proteases with inhibitor-insensitive cysteine proteases. To get a broader insight into the basis of larval adaptation to plant defenses, we created a "suppression subtractive hybridisation" library using cDNA from the gut of L. decemlineata larvae fed methyl jasmonate-induced or uninduced potato leaves. Four hundred clones, randomly selected from the library, were screened for their relevance to adaptation with DNA microarray hybridizations. Selected enzyme systems of beetle digestion were further inspected for changes in gene expression using quantitative PCR and enzyme activity measurements. We identified two new groups of digestive cysteine proteases, intestains D and intestains E. Intestains D represent a group of structurally distinct digestive cysteine proteases, of which the tested members are strongly upregulated in response to induced plant defenses. Moreover, we found that other digestive enzymes also participate in adaptation, namely, cellulases, serine proteases, and an endopolygalacturonase. In addition, juvenile hormone binding protein-like (JHBP-like) genes were upregulated. All studied genes were expressed specifically in larval guts. In contrast to earlier studies that reported experiments based on PI-enriched artificial diets, our results increase understanding of insect adaptation under natural conditions.

  14. Mechanisms of intracellular defense and activity of free radical oxidation in rat myocardium in the dynamics of chronic fluorine intoxication.

    PubMed

    Zhukova, A G; Alekhina, D A; Sazontova, T G; Prokop'ev, Yu A; Gorokhova, L G; Stryapko, N V; Mikhailova, N N

    2013-12-01

    The mechanisms of intracellular defense and activity of free radical oxidation in the myocardium were studied in the dynamics of chronic fluorine intoxication. At the early stages of fluorine intoxication (day 3-week 3), the concentrations of defense proteins HIF-1α, HSC73, and HOx-2 and activity of the main metabolic enzymes increased, which promoted maintenance of cardiomyocyte structure and function at the normal physiological level. At late stages of fluorine intoxication (weeks 6 and 9), metabolic changes in the myocardium attest to high strain of the adaptive mechanisms.

  15. Do toxic heavy metals affect antioxidant defense mechanisms in humans?

    PubMed

    Wieloch, Monika; Kamiński, Piotr; Ossowska, Anna; Koim-Puchowska, Beata; Stuczyński, Tomasz; Kuligowska-Prusińska, Magdalena; Dymek, Grażyna; Mańkowska, Aneta; Odrowąż-Sypniewska, Grażyna

    2012-04-01

    The aim of this study was to prove whether anthropogenic pollution affects antioxidant defense mechanisms such as superoxide dismutase (SOD) and catalase (CAT) activity, ferritin (FRT) concentration and total antioxidant status (TAS) in human serum. The study area involves polluted and salted environment (Kujawy region; northern-middle Poland) and Tuchola Forestry (unpolluted control area). We investigated 79 blood samples of volunteers from polluted area and 82 from the control in 2008 and 2009. Lead, cadmium and iron concentrations were measured in whole blood by the ICP-MS method. SOD and CAT activities were measured in serum using SOD and CAT Assay Kits by the standardized colorimetric method. Serum TAS was measured spectrophotometrically by the modified Benzie and Strain (1996) method and FRT concentration-by the immunonefelometric method. Pb and Cd levels and SOD activity were higher in volunteers from polluted area as compared with those from the control (0.0236 mg l(-1) vs. 0.014 mg l(-1); 0.0008 mg l(-1) vs. 0.0005 mg l(-1); 0.137 Um l(-1) vs. 0.055 Um l(-1), respectively). Fe level, CAT activity and TAS were lower in serum of volunteers from polluted area (0.442 g l(-1) vs. 0.476 gl(-1); 3.336 nmol min(-1)ml(-1) vs. 6.017 nmol min(-1)ml(-1); 0.731 Trolox-equivalents vs. 0.936 Trolox-equivalents, respectively), whilst differences in FRT concentration were not significant (66.109 μg l(-1) vs. 37.667 μg l(-1), p=0.3972). Positive correlations between Pb (r=0.206), Cd (r=0.602) and SOD in the inhabitants of polluted area, and between Cd and SOD in the control (r=0.639) were shown. In volunteers from both studied environments TAS-FRT (polluted: r=0.625 vs. control: r=0.837) and Fe-FRT (polluted area: r=0.831 vs. control: r=0.407) correlations, and Pb-FRT (r=0.360) and Pb-TAS (r=0.283) in the control were stated. The higher lead and cadmium concentrations in blood cause an increase of SOD activity. It suggests that this is one of the defense mechanisms of an

  16. The comprehensive assessment of defense style: measuring defense mechanisms in children and adolescents.

    PubMed

    Laor, N; Wolmer, L; Cicchetti, D V

    2001-06-01

    This study introduces the Comprehensive Assessment of Defense Style (CADS), a new method to assess descriptively the defensive behavior of children and adolescents. Parents of 124 children and adolescents referred to a mental health clinic, of 104 nontreated children, and of 15 children whose fathers were treated for posttraumatic stress disorder completed the CADS. Factor analysis of 28 defenses yielded one mature factor, one immature factor of defenses expressed in relations with the environment (other-oriented), and one of defenses expressed in relations with the self (self-oriented). The CADS significantly discriminated between patients and nonpatients. Psychiatric patients used more immature and fewer mature defenses than control subjects, and adolescents used more mature and fewer other-oriented defenses than children. Girls used more mature and fewer other-oriented defenses than boys. The reliability and validity data of the CADS are encouraging. The three defense factors may be implemented for diagnostic and clinical purposes as well as for screening for psychopathology risk in untreated populations.

  17. Heavy Metal Stress and Some Mechanisms of Plant Defense Response

    PubMed Central

    Emamverdian, Abolghassem; Ding, Yulong; Mokhberdoran, Farzad; Xie, Yinfeng

    2015-01-01

    Unprecedented bioaccumulation and biomagnification of heavy metals (HMs) in the environment have become a dilemma for all living organisms including plants. HMs at toxic levels have the capability to interact with several vital cellular biomolecules such as nuclear proteins and DNA, leading to excessive augmentation of reactive oxygen species (ROS). This would inflict serious morphological, metabolic, and physiological anomalies in plants ranging from chlorosis of shoot to lipid peroxidation and protein degradation. In response, plants are equipped with a repertoire of mechanisms to counteract heavy metal (HM) toxicity. The key elements of these are chelating metals by forming phytochelatins (PCs) or metallothioneins (MTs) metal complex at the intra- and intercellular level, which is followed by the removal of HM ions from sensitive sites or vacuolar sequestration of ligand-metal complex. Nonenzymatically synthesized compounds such as proline (Pro) are able to strengthen metal-detoxification capacity of intracellular antioxidant enzymes. Another important additive component of plant defense system is symbiotic association with arbuscular mycorrhizal (AM) fungi. AM can effectively immobilize HMs and reduce their uptake by host plants via binding metal ions to hyphal cell wall and excreting several extracellular biomolecules. Additionally, AM fungi can enhance activities of antioxidant defense machinery of plants. PMID:25688377

  18. Heavy metal stress and some mechanisms of plant defense response.

    PubMed

    Emamverdian, Abolghassem; Ding, Yulong; Mokhberdoran, Farzad; Xie, Yinfeng

    2015-01-01

    Unprecedented bioaccumulation and biomagnification of heavy metals (HMs) in the environment have become a dilemma for all living organisms including plants. HMs at toxic levels have the capability to interact with several vital cellular biomolecules such as nuclear proteins and DNA, leading to excessive augmentation of reactive oxygen species (ROS). This would inflict serious morphological, metabolic, and physiological anomalies in plants ranging from chlorosis of shoot to lipid peroxidation and protein degradation. In response, plants are equipped with a repertoire of mechanisms to counteract heavy metal (HM) toxicity. The key elements of these are chelating metals by forming phytochelatins (PCs) or metallothioneins (MTs) metal complex at the intra- and intercellular level, which is followed by the removal of HM ions from sensitive sites or vacuolar sequestration of ligand-metal complex. Nonenzymatically synthesized compounds such as proline (Pro) are able to strengthen metal-detoxification capacity of intracellular antioxidant enzymes. Another important additive component of plant defense system is symbiotic association with arbuscular mycorrhizal (AM) fungi. AM can effectively immobilize HMs and reduce their uptake by host plants via binding metal ions to hyphal cell wall and excreting several extracellular biomolecules. Additionally, AM fungi can enhance activities of antioxidant defense machinery of plants. PMID:25688377

  19. Adaptation of inducible defense in Euplotes daidaleos (Ciliophora) to predation risks by various predators.

    PubMed

    Kusch, J

    1995-07-01

    The extent of induced morphological defense in Euplotes daidaleos correlates to this ciliate's predation risk from the defense-inducing predator species. Euplotes daidaleos responded by morphological transformation only to organisms that are able to feed on typically formed Euplotes cells (63 ± 5 μm cell width in E. daidaleos). Three of those potential predator species caused defensive changes to various degrees (Student's t-test, P < 0.1 to P < 0.0001): Lembadion bullinum (Ciliata) induced 82 ± 6 μm cell width in E. daidaleos; Chaetogaster diastrophus (Oligochaeta) induced 85 = 6 μm width; and Stenostomum sphagnetorum (Turbellaria) induced 89 ± 8 μm width (at a density of 10 predators per milliliter, respectively). At higher predator densities (50 or 100 organisms per milliliter), Euplotes developed a correspondingly larger width (to a maximum of 103 ± 10 μm in the presence of S. sphagnetorum). Euplotes did not respond to organisms (e.g., Blepharisma japonicum, Colpidium campylum, Didinium nasutum, Paramecium caudatum, Spirostomum ambiguum, Stentor coeruleus) that cannot feed on this ciliate species. Daphnia longispina and Bursaria truncatella predators, which can feed on large prey of ≥125, or ≥200 μm in diameter, respectively, also had no effect on the morphology of Euplotes. The extent of defense in Euplotes that was induced by 10 predators per milliliter during 24 h decreased the predation risk from those predators to 67% in the presence of S. sphagnetorum, to 50% with L. bullinum, and to 15% with C. diastrophus, compared to the typical form of Euplotes. In a natural population, the defensive form of E. daidaleos was found with average cell widths of 88 ± 8 μm. The results indicate that predator-induced defense in natural Euplotes populations is beneficial to this prey and that it is adapted to the predation abilities of Euplotes predators, whereby energetical costs related to defensive changes may be saved. PMID:24185414

  20. Host defense mechanism-based rational design of live vaccine.

    PubMed

    Jang, Yo Han; Byun, Young Ho; Lee, Kwang-Hee; Park, Eun-Sook; Lee, Yun Ha; Lee, Yoon-Jae; Lee, Jinhee; Kim, Kyun-Hwan; Seong, Baik Lin

    2013-01-01

    Live attenuated vaccine (LAV), mimicking natural infection, provides an excellent protection against microbial infection. The development of LAV, however, still remains highly empirical and the rational design of clinically useful LAV is scarcely available. Apoptosis and caspase activation are general host antiviral responses in virus-infected cells. Utilizing these tightly regulated host defense mechanisms, we present a novel apoptosis-triggered attenuation of viral virulence as a rational design of live attenuated vaccine with desired levels of safety, efficacy, and productivity. Mutant influenza viruses carrying caspase recognition motifs in viral NP and the interferon-antagonist NS1 proteins were highly attenuated both in vitro and in vivo by caspase-mediated cleavage of those proteins in infected cells. Both viral replication and interferon-resistance were substantially reduced, resulting in a marked attenuation of virulence of the virus. Despite pronounced attenuation, the viruses demonstrated high growth phenotype in embryonated eggs at lower temperature, ensuring its productivity. A single dose vaccination with the mutant virus elicited high levels of systemic and mucosal antibody responses and provided complete protection against both homologous and heterologous lethal challenges in mouse model. While providing a practical means to generate seasonal or pandemic influenza live vaccines, the sensitization of viral proteins to pathogen-triggered apoptotic signals presents a potentially universal, mechanism-based rational design of live vaccines against many viral infections.

  1. Change in Coping and Defense Mechanisms across Adulthood: Longitudinal Findings in a European American Sample

    ERIC Educational Resources Information Center

    Diehl, Manfred; Chui, Helena; Hay, Elizabeth L.; Lumley, Mark A.; Grühn, Daniel; Labouvie-Vief, Gisela

    2014-01-01

    This study examined longitudinal changes in coping and defense mechanisms in an age- and gender-stratified sample of 392 European American adults. Nonlinear age-related changes were found for the coping mechanisms of sublimation and suppression and the defense mechanisms of intellectualization, doubt, displacement, and regression. The change…

  2. Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

    PubMed Central

    Spit, Jornt; Holtof, Michiel; Badisco, Liesbet; Vergauwen, Lucia; Vogel, Elise; Knapen, Dries; Vanden Broeck, Jozef

    2016-01-01

    Herbivorous insects evolved adaptive mechanisms to compensate for the presence of plant defensive protease inhibitors (PI) in their food. The underlying regulatory mechanisms of these compensatory responses remain largely elusive. In the current study, we investigated the initiation of this adaptive response in the migratory locust, Locusta migratoria, via microarray analysis of gut tissues. Four hours after dietary uptake of PIs, 114 and 150 transcripts were respectively found up- or downregulated. The results suggest a quick trade-off between compensating for potential loss of digestive activity on the one hand, and stress tolerance, defense, and structural integrity of the gut on the other hand. We additionally addressed the role of a group of related upregulated hexamerin-like proteins in the PI-induced response. Simultaneous knockdown of corresponding transcripts by means of RNA interference resulted in a reduced capacity of the locust nymphs to cope with the effects of PI. Moreover, since insect hexamerins have been shown to bind Juvenile Hormone (JH), we also investigated the effect of JH on the proteolytic digestion in L. migratoria. Our results indicate that JH has a stimulatory effect on the expression of three homologous chymotrypsin genes, while knocking down the JH receptor (methoprene tolerant) led to opposite effects. PMID:27581362

  3. Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

    NASA Astrophysics Data System (ADS)

    Spit, Jornt; Holtof, Michiel; Badisco, Liesbet; Vergauwen, Lucia; Vogel, Elise; Knapen, Dries; vanden Broeck, Jozef

    2016-09-01

    Herbivorous insects evolved adaptive mechanisms to compensate for the presence of plant defensive protease inhibitors (PI) in their food. The underlying regulatory mechanisms of these compensatory responses remain largely elusive. In the current study, we investigated the initiation of this adaptive response in the migratory locust, Locusta migratoria, via microarray analysis of gut tissues. Four hours after dietary uptake of PIs, 114 and 150 transcripts were respectively found up- or downregulated. The results suggest a quick trade-off between compensating for potential loss of digestive activity on the one hand, and stress tolerance, defense, and structural integrity of the gut on the other hand. We additionally addressed the role of a group of related upregulated hexamerin-like proteins in the PI-induced response. Simultaneous knockdown of corresponding transcripts by means of RNA interference resulted in a reduced capacity of the locust nymphs to cope with the effects of PI. Moreover, since insect hexamerins have been shown to bind Juvenile Hormone (JH), we also investigated the effect of JH on the proteolytic digestion in L. migratoria. Our results indicate that JH has a stimulatory effect on the expression of three homologous chymotrypsin genes, while knocking down the JH receptor (methoprene tolerant) led to opposite effects.

  4. Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors.

    PubMed

    Spit, Jornt; Holtof, Michiel; Badisco, Liesbet; Vergauwen, Lucia; Vogel, Elise; Knapen, Dries; Vanden Broeck, Jozef

    2016-01-01

    Herbivorous insects evolved adaptive mechanisms to compensate for the presence of plant defensive protease inhibitors (PI) in their food. The underlying regulatory mechanisms of these compensatory responses remain largely elusive. In the current study, we investigated the initiation of this adaptive response in the migratory locust, Locusta migratoria, via microarray analysis of gut tissues. Four hours after dietary uptake of PIs, 114 and 150 transcripts were respectively found up- or downregulated. The results suggest a quick trade-off between compensating for potential loss of digestive activity on the one hand, and stress tolerance, defense, and structural integrity of the gut on the other hand. We additionally addressed the role of a group of related upregulated hexamerin-like proteins in the PI-induced response. Simultaneous knockdown of corresponding transcripts by means of RNA interference resulted in a reduced capacity of the locust nymphs to cope with the effects of PI. Moreover, since insect hexamerins have been shown to bind Juvenile Hormone (JH), we also investigated the effect of JH on the proteolytic digestion in L. migratoria. Our results indicate that JH has a stimulatory effect on the expression of three homologous chymotrypsin genes, while knocking down the JH receptor (methoprene tolerant) led to opposite effects. PMID:27581362

  5. Ego defense mechanisms in Pakistani medical students: a cross sectional analysis

    PubMed Central

    2010-01-01

    Background Ego defense mechanisms (or factors), defined by Freud as unconscious resources used by the ego to reduce conflict between the id and superego, are a reflection of how an individual deals with conflict and stress. This study assesses the prevalence of various ego defense mechanisms employed by medical students of Karachi, which is a group with higher stress levels than the general population. Methods A questionnaire based cross-sectional study was conducted on 682 students from five major medical colleges of Karachi over 4 weeks in November 2006. Ego defense mechanisms were assessed using the Defense Style Questionnaire (DSQ-40) individually and as grouped under Mature, Immature, and Neurotic factors. Results Lower mean scores of Immature defense mechanisms (4.78) were identified than those for Neurotic (5.62) and Mature (5.60) mechanisms among medical students of Karachi. Immature mechanisms were more commonly employed by males whereas females employed more Neurotic mechanisms than males. Neurotic and Immature defenses were significantly more prevalent in first and second year students. Mature mechanisms were significantly higher in students enrolled in Government colleges than Private institutions (p < 0.05). Conclusions Immature defense mechanisms were less commonly employed than Neurotic and Mature mechanisms among medical students of Karachi. The greater employment of Neurotic defenses may reflect greater stress levels than the general population. Employment of these mechanisms was associated with female gender, enrollment in a private medical college, and students enrolled in the first 2 years of medical school. PMID:20109240

  6. Genome adaptations of a tripartite motif protein for retroviral defense in cattle and sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tripartite motif (TRIM) genes encode proteins composed of RING, B-box, and coiled coil motif domains. Primate TRIM5' has been shown to be a primary determinant of retroviral host cell range restriction in primates. TRIM5 restriction was originally thought to be a primate-specific defense mechanism...

  7. Turning inducible defenses on and off: adaptive responses of Daphnia to a gape-limited predator.

    PubMed

    Riessen, Howard P; Trevett-Smith, Julie B

    2009-12-01

    The use of inducible defenses is a common strategy to reduce predation while minimizing associated costs for prey. The most effective use of these defenses, however, may involve turning them on and off at different stages of ontogenetic development, with the timing dependent on prey body size and the nature of the predation environment. We develop a model based on the strike efficiency of a size-selective predator that examines the interaction between induced morphological defenses and prey body size, including the consequences of this interaction for the optimal development of the defenses during the prey's ontogeny. We then examine this model with respect to a model system of inducible defenses: neck spine induction in the water flea Daphnia in response to predatory larvae of the phantom midge Chaoborus. In accordance with predictions of the model, the body size and timing of neck spine acquisition during Daphnia development are related to the relative sizes of the Daphnia and Chaoborus species interacting in a pond or lake. The Daphnia species examined first acquire neck spines in either the first, second, or third juvenile instar, at body lengths that range from 0.58 to 0.83 mm. Neck spine formation is initiated at larger Daphnia body sizes when these prey are subject to predation by a larger Chaoborus species (C. trivittatus) and at smaller sizes when exposed only to a smaller predator (C. americanus). Induction of these morphological defenses in Daphnia occurs later in juvenile development in the smaller of the two species we examined (D. minnehaha) than in the larger (D. pulex). Delayed acquisition of neck spines also occurs when Daphnia are exposed to predation by larger Chaoborus. The close match between model predictions and the patterns observed in nature suggests that these patterns are adaptive developmental responses to different predator environments.

  8. Adaptive evolution of defense ability leads to diversification of prey species.

    PubMed

    Zu, Jian; Wang, Jinliang; Du, Jianqiang

    2014-06-01

    In this paper, by using the adaptive dynamics approach, we investigate how the adaptive evolution of defense ability promotes the diversity of prey species in an initial one-prey-two-predator community. We assume that the prey species can evolve to a safer strategy such that it can reduce the predation risk, but a prey with a high defense ability for one predator may have a low defense ability for the other and vice versa. First, by using the method of critical function analysis, we find that if the trade-off is convex in the vicinity of the evolutionarily singular strategy, then this singular strategy is a continuously stable strategy. However, if the trade-off is weakly concave near the singular strategy and the competition between the two predators is relatively weak, then the singular strategy may be an evolutionary branching point. Second, we find that after the branching has occurred in the prey strategy, if the trade-off curve is globally concave, then the prey species might eventually evolve into two specialists, each caught by only one predator species. However, if the trade-off curve is convex-concave-convex, the prey species might eventually branch into two partial specialists, each being caught by both of the two predators and they can stably coexist on the much longer evolutionary timescale.

  9. Serine/threonine protein phosphatases: multi-purpose enzymes in control of defense mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Serine/threonine protein phosphatases are a group of enzymes involved in the regulation of defense mechanisms in plants. This paper describes the effects of an inhibitor of these enzymes on the expression of all of the genes associated with these defense mechanisms. The results suggest that inhibi...

  10. Mechanisms of Defense against Intracellular Pathogens Mediated by Human Macrophages.

    PubMed

    Bloom, Barry R; Modlin, Robert L

    2016-06-01

    The key question our work has sought to address has been, "What are the necessary and sufficient conditions that engender protection from intracellular pathogens in the human host?" The origins of this work derive from a long-standing interest in the mechanisms of protection against two such paradigmatic intracellular pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, that have brilliantly adapted to the human host. It was obvious that these pathogens, which cause chronic diseases and persist in macrophages, must have acquired subtle strategies to resist host microbicidal mechanisms, yet since the vast majority of individuals infected with M. tuberculosis do not develop disease, there must be some potent human antimicrobial mechanisms. What follows is not a comprehensive review of the vast literature on the role of human macrophages in protection against infectious disease, but a summary of the research in our two laboratories with collaborators that we hope has contributed to some understanding of mechanisms of resistance and pathogenesis. While mouse models revealed some necessary conditions for protection, e.g., innate immunity, Th1 cells and their cytokines, and major histocompatibility complex class I-restricted T cells, here we emphasize multiple antimicrobial mechanisms that exist in human macrophages that differ from those of most experimental animals. Prominent here is the vitamin D-dependent antimicrobial pathway common to human macrophages activated by innate and acquired immune responses, mediated by antimicrobial peptides, e.g., cathelicidin, through an interleukin-15- and interleukin-32-dependent common pathway that is necessary for macrophage killing of M. tuberculosis in vitro. PMID:27337485

  11. Anomalies and specific functions in the clinical identification of defense mechanisms.

    PubMed

    Perry, J Christopher

    2014-05-01

    Standard teaching about defense mechanisms generally focuses on definitions, which do not readily aid the clinician in identifying defenses whenever individuals use them. This report demonstrates a process by which the clinician can identify when a defense is used, which ones are likely being used, and with what aim. Clinicians first notice that a defense may be operating whenever the other individual presents with anomalies in the expression of affect, behavior, speech, or its content. Some of these anomalies are described. Next, to identify the specific defense or general level of defensive functioning used, the clinician must identify the specific function of the defense in context using a process of guided clinical inference. This report examines 2 verbatim examples from recorded interviews of one case to demonstrate this process. The examples present a microcosm of clinical concerns that have a surprising relationship to the individual's course and prognosis.

  12. Mechanical defenses of plant extrafloral nectaries against herbivory

    PubMed Central

    Gish, Moshe; Mescher, Mark C.; De Moraes, Consuelo M.

    2016-01-01

    ABSTRACT Extrafloral nectaries play an important role in plant defense against herbivores by providing nectar rewards that attract ants and other carnivorous insects. However, extrafloral nectaries can themselves be targets of herbivory, in addition to being exploited by nectar-robbing insects that do not provide defensive services. We recently found that the extrafloral nectaries of Vicia faba plants, as well as immediately adjacent tissues, exhibit high concentrations of chemical toxins, apparently as a defense against herbivory. Here we report that the nectary tissues of this plant also exhibit high levels of structural stiffness compared to surrounding tissues, likely due to cell wall lignification and the concentration of calcium oxalate crystals in nectary tissues, which may provide an additional deterrent to herbivore feeding on nectary tissues. PMID:27489584

  13. Mechanical defenses of plant extrafloral nectaries against herbivory.

    PubMed

    Gish, Moshe; Mescher, Mark C; De Moraes, Consuelo M

    2016-01-01

    Extrafloral nectaries play an important role in plant defense against herbivores by providing nectar rewards that attract ants and other carnivorous insects. However, extrafloral nectaries can themselves be targets of herbivory, in addition to being exploited by nectar-robbing insects that do not provide defensive services. We recently found that the extrafloral nectaries of Vicia faba plants, as well as immediately adjacent tissues, exhibit high concentrations of chemical toxins, apparently as a defense against herbivory. Here we report that the nectary tissues of this plant also exhibit high levels of structural stiffness compared to surrounding tissues, likely due to cell wall lignification and the concentration of calcium oxalate crystals in nectary tissues, which may provide an additional deterrent to herbivore feeding on nectary tissues. PMID:27489584

  14. Adapting to Health Impacts of Climate Change in the Department of Defense.

    PubMed

    Chrétien, Jean-Paul

    2016-01-01

    The Department of Defense (DoD) recognizes climate change as a threat to its mission and recently issued policy to implement climate change adaptation measures. However, the DoD has not conducted a comprehensive assessment of health-related climate change effects. To catalyze the needed assessment--a first step toward a comprehensive DoD climate change adaptation plan for health--this article discusses the DoD relevance of 3 selected climate change impacts: heat injuries, vector-borne diseases, and extreme weather that could lead to natural disasters. The author uses these examples to propose a comprehensive approach to planning for health-related climate change impacts in the DoD. PMID:27081888

  15. The evolution of advanced mechanical defenses and potential technological applications of diatom shells.

    PubMed

    Hamm, Christian E

    2005-01-01

    Diatoms are unicellular algae with silicified cell walls, which exhibit a high degree of symmetry and complexity. Their diversity is extraordinarily high; estimates suggest that about 10(5) marine and limnic species may exist. Recently, it was shown that diatom frustules are mechanically resilient, statically sophisticated structures made of a tough glass-like composite. Consequently, to break the frustules, predators have to generate large forces and invest large amounts of energy. In addition, they need feeding tools (e.g., mandibles or gastric mills) which are hard, tough, and resilient enough to resist high stress and wear, which are bound to occur when they feed on biomineralized objects such as diatoms or other biomineralized protists. Indeed, many copepods feeding on diatoms possess, in analogy to the enamelcoated teeth of mammals, amazingly complex, silica-laced mandibles. The highly developed adaptations both to protect and to break diatoms indicate that selection pressure is high to optimize material properties and the geometry of the shells to achieve mechanical strength of the overall structure. This paper discusses the mechanical challenges which force the development of mechanical defenses, and the structural components of the diatom frustules which indicate that evolutionary optimization has led to mechanically sophisticated structures. Understanding the diatom frustule from the nanometer scale up to the whole shell will provide new insights to advanced combinations of nanostructured composite ceramic materials and lightweight architecture for technological applications.

  16. Involvement of an antioxidant defense system in the adaptive response to cadmium in maize seedlings (Zea mays L.).

    PubMed

    Xu, Xianghua; Liu, Cuiying; Zhao, Xiaoyan; Li, Renying; Deng, Wenjing

    2014-11-01

    Chemical and biological analyses were used to investigate the growth response and antioxidant defense mechanism of maize seedlings (Zea mays L.) grown in soils with 0-100 mg kg(-1) Cd. Results showed that maize seedlings have strong abilities to accumulate and tolerate high concentrations of Cd. For soil with 50 mg kg(-1) Cd, the Cd contents in roots and shoots of maize seedlings are as large as 295.6 and 153.0 mg kg(-1) DW, respectively, without visible symptoms of toxicity. Lower soil Cd concentrations lead to a decrease in reduced glutathione (GSH) content in leaves of maize seedlings, whereas higher soil Cd concentrations resulted in an increase in the activities of superoxide dismutase, guaiacol peroxidase, catalase, and ascorbate peroxidase. Maize seedlings have strong capacities to adapt to low concentrations of Cd by consuming GSH and to develop an antioxidative enzyme system to defend against high-Cd stress.

  17. Evaluating ego defense mechanisms using clinical interviews: an empirical study of adolescent diabetic and psychiatric patients.

    PubMed

    Jacobson, A M; Beardslee, W; Hauser, S T; Noam, G G; Powers, S I; Houlihan, J; Rider, E

    1986-12-01

    Ego defense mechanisms were studied in three groups of early adolescents: diabetic patients, non-psychotic psychiatric patients, and healthy high school students. Defenses were assessed from ratings of open-ended, in-depth interviews. High levels of denial and low levels of asceticism were found in all three groups. Comparisons between groups indicated that psychiatric patients had a distinctive profile of defense usage, in comparison to adolescents from the other two groups. An independent measure of ego development was positively correlated with the defenses of altruism, intellectualization, and suppression, while it was negatively correlated with acting out, avoidance, denial, displacement, projection, and repression. The findings of substantial differences in defense usage between the psychiatric and non-psychiatric samples, and the size and directions of the correlations with ego development level, lend support to the validity of the defense codes.

  18. The Child's Demystification of Psychological Defense Mechanisms: A Structural and Developmental Analysis.

    ERIC Educational Resources Information Center

    Chandler, Michael J.; And Others

    1978-01-01

    Explored the relationships between the cognitive developmental level of preoperational, concrete operational, and formal operational children (N=10) and their success in interpreting and explaining each of eight commonly described mechanisms of psychological defense. (JMB)

  19. Unconscious Vigilance: Worldview Defense Without Adaptations for Terror, Coalition, or Uncertainty Management

    PubMed Central

    Holbrook, Colin; Sousa, Paulo; Hahn-Holbrook, Jennifer

    2012-01-01

    Individuals subtly reminded of death, coalitional challenges, or feelings of uncertainty display exaggerated preferences for affirmations and against criticisms of their cultural in-groups. Terror management, coalitional psychology, and uncertainty management theories postulate this “worldview defense” effect as the output of mechanisms evolved either to allay the fear of death, foster social support, or reduce anxiety by increasing adherence to cultural values. In 4 studies, we report evidence for an alternative perspective. We argue that worldview defense owes to unconscious vigilance, a state of accentuated reactivity to affective targets (which need not relate to cultural worldviews) that follows detection of subtle alarm cues (which need not pertain to death, coalitional challenges, or uncertainty). In Studies 1 and 2, death-primed participants produced exaggerated ratings of worldview-neutral affective targets. In Studies 3 and 4, subliminal threat manipulations unrelated to death, coalitional challenges, or uncertainty evoked worldview defense. These results are discussed as they inform evolutionary interpretations of worldview defense and future investigations of the influence of unconscious alarm on judgment. PMID:21644809

  20. Adaptive evolution of threonine deaminase in plant defense against insect herbivores

    SciTech Connect

    Gonzales-Vigil, Eliana; Bianchetti, Christopher M.; Phillips, Jr., George N.; Howe, Gregg A.

    2011-11-07

    Gene duplication is a major source of plant chemical diversity that mediates plant-herbivore interactions. There is little direct evidence, however, that novel chemical traits arising from gene duplication reduce herbivory. Higher plants use threonine deaminase (TD) to catalyze the dehydration of threonine (Thr) to {alpha}-ketobutyrate and ammonia as the committed step in the biosynthesis of isoleucine (Ile). Cultivated tomato and related Solanum species contain a duplicated TD paralog (TD2) that is coexpressed with a suite of genes involved in herbivore resistance. Analysis of TD2-deficient tomato lines showed that TD2 has a defensive function related to Thr catabolism in the gut of lepidopteran herbivores. During herbivory, the regulatory domain of TD2 is removed by proteolysis to generate a truncated protein (pTD2) that efficiently degrades Thr without being inhibited by Ile. We show that this proteolytic activation step occurs in the gut of lepidopteran but not coleopteran herbivores, and is catalyzed by a chymotrypsin-like protease of insect origin. Analysis of purified recombinant enzymes showed that TD2 is remarkably more resistant to proteolysis and high temperature than the ancestral TD1 isoform. The crystal structure of pTD2 provided evidence that electrostatic interactions constitute a stabilizing feature associated with adaptation of TD2 to the extreme environment of the lepidopteran gut. These findings demonstrate a role for gene duplication in the evolution of a plant defense that targets and co-opts herbivore digestive physiology.

  1. Multifunctional host defense peptides: antimicrobial peptides, the small yet big players in innate and adaptive immunity.

    PubMed

    Auvynet, Constance; Rosenstein, Yvonne

    2009-11-01

    The term 'antimicrobial peptides' refers to a large number of peptides first characterized on the basis of their antibiotic and antifungal activities. In addition to their role as endogenous antibiotics, antimicrobial peptides, also called host defense peptides, participate in multiple aspects of immunity (inflammation, wound repair, and regulation of the adaptive immune system) as well as in maintaining homeostasis. The possibility of utilizing these multifunctional molecules to effectively combat the ever-growing group of antibiotic-resistant pathogens has intensified research aimed at improving their antibiotic activity and therapeutic potential, without the burden of an exacerbated inflammatory response, but conserving their immunomodulatory potential. In this minireview, we focus on the contribution of small cationic antimicrobial peptides - particularly human cathelicidins and defensins - to the immune response and disease, highlighting recent advances in our understanding of the roles of these multifunctional molecules.

  2. Evolution and development of gastropod larval shell morphology: experimental evidence for mechanical defense and repair.

    PubMed

    Hickman, C S

    2001-01-01

    The structural diversity of gastropod veliger larvae offers an instructive counterpoint to the view of larval forms as conservative archetypes. Larval structure, function, and development are fine-tuned for survival in the plankton. Accordingly, the study of larval adaptation provides an important perspective for evolutionary-developmental biology as an integrated science. Patterns of breakage and repair in the field, as well as patterns of breakage in arranged encounters with zooplankton under laboratory conditions, are two powerful sources of data on the adaptive significance of morphological and microsculptural features of the gastropod larval shell. Shells of the planktonic veliger larvae of the caenogastropod Nassarius paupertus [GOULD] preserve multiple repaired breaks, attributed to unsuccessful zooplankton predators. In culture, larvae isolated from concentrated zooplankton samples rapidly repaired broken apertural margins and restored the "ideal" apertural form, in which an elaborate projection or "beak" covers the head of the swimming veliger. When individuals with repaired apertures were reintroduced to a concentrated mixture of potential zooplankton predators, the repaired margins were rapidly chipped and broken back. The projecting beak of the larval shell is the first line of mechanical defense, covering the larval head and mouth and potentially the most vulnerable part of the shell to breakage. Patterns of mechanical failure show that spiral ridges do reinforce the beak and retard breakage. The capacity for rapid shell repair and regeneration, and the evolution of features that resist or retard mechanical damage, may play a more prominent role than previously thought in enhancing the ability of larvae to survive in the plankton.

  3. Change in children's externalizing and internalizing behavior problems: the role of defense mechanisms.

    PubMed

    Cramer, Phebe

    2015-03-01

    This study investigates the relation of defense mechanism to children's externalizing and internalizing behavior problems, as assessed from mothers' report at age 9 and 12 years, based on archival data. The defense mechanisms of denial, projection, and identification were assessed from Thematic Apperception Test stories told by the children at age 9 years, using the Defense Mechanism Manual (Cramer, The development of defense mechanisms: Theory, research and assessment. New York: Springer-Verlag, 1991a; Protecting the self: Defense mechanisms in action. New York: Guilford Press, 2006). The results showed that the use of identification predicted a decrease in externalizing behaviors between age 9 and 12 years. In contrast, change in internalizing behaviors was not predicted by defense use, but the use of projection was related to fewer internalizing behaviors at both ages. These findings are consistent with the idea that behavioral intervention stressing self-regulation can be effective in reducing externalizing problems, but internalizing problems require an intervention that is sensitive to the underlying behavioral inhibition in these children.

  4. Change in children's externalizing and internalizing behavior problems: the role of defense mechanisms.

    PubMed

    Cramer, Phebe

    2015-03-01

    This study investigates the relation of defense mechanism to children's externalizing and internalizing behavior problems, as assessed from mothers' report at age 9 and 12 years, based on archival data. The defense mechanisms of denial, projection, and identification were assessed from Thematic Apperception Test stories told by the children at age 9 years, using the Defense Mechanism Manual (Cramer, The development of defense mechanisms: Theory, research and assessment. New York: Springer-Verlag, 1991a; Protecting the self: Defense mechanisms in action. New York: Guilford Press, 2006). The results showed that the use of identification predicted a decrease in externalizing behaviors between age 9 and 12 years. In contrast, change in internalizing behaviors was not predicted by defense use, but the use of projection was related to fewer internalizing behaviors at both ages. These findings are consistent with the idea that behavioral intervention stressing self-regulation can be effective in reducing externalizing problems, but internalizing problems require an intervention that is sensitive to the underlying behavioral inhibition in these children. PMID:25668653

  5. Developmental patterns of antioxidant defense mechanisms in human erythrocytes.

    PubMed

    Ripalda, M J; Rudolph, N; Wong, S L

    1989-10-01

    To obtain a profile of erythrocyte antioxidant defense potential during late fetal development, we studied selected antioxidant parameters in blood samples from 65 neonates with birth wt between 520 and 4210 g and from 12 healthy adults. Erythrocyte superoxide dismutase activity did not change significantly with maturation and no significant differences were observed among preterm infants grouped in increasing birth wt categories, term neonates, and adults. Erythrocyte catalase and glutathione peroxidase, as well as plasma vitamin E levels, showed highly significant positive correlations (p less than 0.001) with increasing fetal wt and gestational age; by term, CAT activity reached a level similar to the adult control group, but glutathione peroxidase activity, as well as plasma vitamin E levels, were markedly lower in all the preterm and in the term groups than in adults (p less than 0.01). Erythrocyte glutathione S-transferase activity showed a negative correlation with increasing gestational age (p less than 0.01) and the adult values were considerably lower than any of the neonatal levels (p less than 0.001). The role of glutathione S-transferase in erythrocyte metabolism remains obscure. Maturational changes in the activity of the red cell enzymes that were studied and in the plasma vitamin E level were apparent from about 31-36 wk of gestation, suggesting that the stimulation for these changes may have commenced from about 28-31 wk.

  6. In Defense of a Heuristic Interpretation of Quantum Mechanics

    ERIC Educational Resources Information Center

    Healy, Eamonn F.

    2010-01-01

    Although the presentation of quantum mechanics found in traditional textbooks is intellectually well founded, it suffers from a number of deficiencies. Specifically introducing quantum mechanics as a solution to the arcane dilemma, the ultraviolet catastrophe, does little to impress a nonscientific audience of the tremendous paradigmatic shift…

  7. An empirical look at the Defense Mechanism Test (DMT): reliability and construct validity.

    PubMed

    Ekehammar, Bo; Zuber, Irena; Konstenius, Marja-Liisa

    2005-07-01

    Although the Defense Mechanism Test (DMT) has been in use for almost half a century, there are still quite contradictory views about whether it is a reliable instrument, and if so, what it really measures. Thus, based on data from 39 female students, we first examined DMT inter-coder reliability by analyzing the agreement among trained judges in their coding of the same DMT protocols. Second, we constructed a "parallel" photographic picture that retained all structural characteristic of the original and analyzed DMT parallel-test reliability. Third, we examined the construct validity of the DMT by (a) employing three self-report defense-mechanism inventories and analyzing the intercorrelations between DMT defense scores and corresponding defenses in these instruments, (b) studying the relationships between DMT responses and scores on trait and state anxiety, and (c) relating DMT-defense scores to measures of self-esteem. The main results showed that the DMT can be coded with high reliability by trained coders, that the parallel-test reliability is unsatisfactory compared to traditional psychometric standards, that there is a certain generalizability in the number of perceptual distortions that people display from one picture to another, and that the construct validation provided meager empirical evidence for the conclusion that the DMT measures what it purports to measure, that is, psychological defense mechanisms.

  8. A shared mechanism of defense against predators and parasites: chitin regulation and its implications for life-history theory

    PubMed Central

    Beckerman, Andrew P; de Roij, Job; Dennis, Stuart R; Little, Tom J

    2013-01-01

    Defenses against predators and parasites offer excellent illustrations of adaptive phenotypic plasticity. Despite vast knowledge about such induced defenses, they have been studied largely in isolation, which is surprising, given that predation and parasitism are ubiquitous and act simultaneously in the wild. This raises the possibility that victims must trade-off responses to predation versus parasitism. Here, we propose that arthropod responses to predators and parasites will commonly be based on the endocrine regulation of chitin synthesis and degradation. The proposal is compelling because many inducible defenses are centered on temporal or spatial modifications of chitin-rich structures. Moreover, we show how the chitin synthesis pathway ends in a split to carapace or gut chitin, and how this form of molecular regulation can be incorporated into theory on life-history trade-offs, specifically the Y-model. Our hypothesis thus spans several biological scales to address advice from Stearns that “Endocrine mechanisms may prove to be only the tip of an iceberg of physiological mechanisms that modulate the expression of genetic covariance”. PMID:24455141

  9. A shared mechanism of defense against predators and parasites: chitin regulation and its implications for life-history theory.

    PubMed

    Beckerman, Andrew P; de Roij, Job; Dennis, Stuart R; Little, Tom J

    2013-12-01

    Defenses against predators and parasites offer excellent illustrations of adaptive phenotypic plasticity. Despite vast knowledge about such induced defenses, they have been studied largely in isolation, which is surprising, given that predation and parasitism are ubiquitous and act simultaneously in the wild. This raises the possibility that victims must trade-off responses to predation versus parasitism. Here, we propose that arthropod responses to predators and parasites will commonly be based on the endocrine regulation of chitin synthesis and degradation. The proposal is compelling because many inducible defenses are centered on temporal or spatial modifications of chitin-rich structures. Moreover, we show how the chitin synthesis pathway ends in a split to carapace or gut chitin, and how this form of molecular regulation can be incorporated into theory on life-history trade-offs, specifically the Y-model. Our hypothesis thus spans several biological scales to address advice from Stearns that "Endocrine mechanisms may prove to be only the tip of an iceberg of physiological mechanisms that modulate the expression of genetic covariance".

  10. Serine/threonine protein phosphatases: multi-purpose enzymes in control of defense mechanisms.

    PubMed

    Bajsa, Joanna; Pan, Zhiqiang; Duke, Stephen O

    2011-12-01

    Depending on the threat to a plant, different pattern recognition receptors, such as receptor-like kinases, identify the stress and trigger action by appropriate defense response development. The plant immunity system primary response to these challenges is rapid accumulation of phytohormones, such as ethylene (ET), salicylic acid (SA), and jasmonic acid (JA) and its derivatives. These phytohormones induce further signal transduction and appropriate defenses against biotic threats. Phytohormones play crucial roles not only in the initiation of diverse downstream signaling events in plant defense but also in the activation of effective defenses through an essential process called signaling pathway crosstalk, a mechanism involved in transduction signals between two or more distinct, "linear signal transduction pathways simultaneously activated in the same cell."

  11. Academic cheating as a function of defense mechanisms and object relations.

    PubMed

    Juni, Samuel; Gross, Julie; Sokolowska, Joanna

    2006-06-01

    This study examined relationships between academic cheating behaviors by using self-reports of past cheating behavior, providing a situational experiment with the opportunity to cheat, and evaluating defense mechanisms and object relations as measured by the Defense Mechanisms Inventory. Subjects included 75 female and 8 male university students ranging in age from 18 to 51 years (M=25.5, SD=6.9). Analysis showed variations in students' self-reported cheating history relative to their measured object relations status and type of defense mechanisms. Actual cheating in the experimental setting was not significantly related to any of these variables. Findings are discussed based on a critique of heterogeneity of the cheating construct.

  12. Coping and Defense Mechanisms of Mothers of Learning Disabled Children.

    ERIC Educational Resources Information Center

    Faerstein, Leslie Morrison

    1986-01-01

    Mothers (N=24) generally evidenced coping mechanisms when involved with medical, social, and educational agencies, and were able to obtain services. However, coping functions broke down in direct confrontation with the child. Mothers, contrary to traditional attitudes, experienced relief at receiving a diagnosis, confirming their suspicions rather…

  13. Pseudechis australis venomics: adaptation for a defense against microbial pathogens and recruitment of body transferrin.

    PubMed

    Georgieva, Dessislava; Seifert, Jana; Öhler, Michaela; von Bergen, Martin; Spencer, Patrick; Arni, Raghuvir K; Genov, Nicolay; Betzel, Christian

    2011-05-01

    The venom composition of Pseudechis australis, a widely distributed in Australia reptile, was analyzed by 2-DE and mass spectrometric analysis. In total, 102 protein spots were identified as venom toxins. The gel is dominated by horizontal trains of spots with identical or very similar molecular masses but differing in the pI values. This suggests possible post-translational modifications of toxins, changing their electrostatic charge. The results demonstrate a highly specialized biosynthesis of toxins destroying the hemostasis (P-III metalloproteases, SVMPs), antimicrobial proteins (L-amino acid oxidases, LAAOs, and transferrin-like proteins, TFLPs), and myotoxins (phospholipase A(2)s, PLA(2)s). The three transferrin isoforms of the Australian P. australis (Elapidae snake) venom are highly homologous to the body transferrin of the African Lamprophis fuliginosus (Colubridae), an indication for the recruitment of body transferrin. The venomic composition suggests an adaptation for a defense against microbial pathogens from the prey. Transferrins have not previously been reported as components of elapid or other snake venoms. Ecto-5'-nucleotidases (5'-NTDs), nerve growth factors (VNGFs), and a serine proteinase inhibitor (SPI) were also identified. The venom composition and enzymatic activities explain the clinical manifestation of the king brown snakebite. The results can be used for medical, scientific, and biotechnological purposes. PMID:21417486

  14. Pseudechis australis venomics: adaptation for a defense against microbial pathogens and recruitment of body transferrin.

    PubMed

    Georgieva, Dessislava; Seifert, Jana; Öhler, Michaela; von Bergen, Martin; Spencer, Patrick; Arni, Raghuvir K; Genov, Nicolay; Betzel, Christian

    2011-05-01

    The venom composition of Pseudechis australis, a widely distributed in Australia reptile, was analyzed by 2-DE and mass spectrometric analysis. In total, 102 protein spots were identified as venom toxins. The gel is dominated by horizontal trains of spots with identical or very similar molecular masses but differing in the pI values. This suggests possible post-translational modifications of toxins, changing their electrostatic charge. The results demonstrate a highly specialized biosynthesis of toxins destroying the hemostasis (P-III metalloproteases, SVMPs), antimicrobial proteins (L-amino acid oxidases, LAAOs, and transferrin-like proteins, TFLPs), and myotoxins (phospholipase A(2)s, PLA(2)s). The three transferrin isoforms of the Australian P. australis (Elapidae snake) venom are highly homologous to the body transferrin of the African Lamprophis fuliginosus (Colubridae), an indication for the recruitment of body transferrin. The venomic composition suggests an adaptation for a defense against microbial pathogens from the prey. Transferrins have not previously been reported as components of elapid or other snake venoms. Ecto-5'-nucleotidases (5'-NTDs), nerve growth factors (VNGFs), and a serine proteinase inhibitor (SPI) were also identified. The venom composition and enzymatic activities explain the clinical manifestation of the king brown snakebite. The results can be used for medical, scientific, and biotechnological purposes.

  15. [Genetic and biochemical mechanisms of involvement of antioxidant defense enzymes in the development of bronchial asthma].

    PubMed

    Polonikov, A V; Ivanov, V P; Bogomazov, A D; Solodilova, M A

    2015-01-01

    In the present review we have analyzed and summarized recent literature data on genetic and biochemical mechanisms responsible for involvement of antioxidant defense enzymes in the etiology and pathogenesis of bronchial asthma. It has been shown that the mechanisms of asthma development are linked with genetically determined abnormalities in the functioning of antioxidant defense enzymes. These alterations are accompanied by a systemic imbalance between oxidative and anti-oxidative reactions with the shift of the redox state toward increased free radical production and oxidative stress, a key element in the pathogenesis of bronchial asthma. PMID:26350733

  16. [Genetic and biochemical mechanisms of involvement of antioxidant defense enzymes in the development of bronchial asthma].

    PubMed

    Polonikov, A V; Ivanov, V P; Bogomazov, A D; Solodilova, M A

    2015-01-01

    In the present review we have analyzed and summarized recent literature data on genetic and biochemical mechanisms responsible for involvement of antioxidant defense enzymes in the etiology and pathogenesis of bronchial asthma. It has been shown that the mechanisms of asthma development are linked with genetically determined abnormalities in the functioning of antioxidant defense enzymes. These alterations are accompanied by a systemic imbalance between oxidative and anti-oxidative reactions with the shift of the redox state toward increased free radical production and oxidative stress, a key element in the pathogenesis of bronchial asthma.

  17. Adaptive mechanically controlled lubrication mechanism found in articular joints.

    PubMed

    Greene, George W; Banquy, Xavier; Lee, Dong Woog; Lowrey, Daniel D; Yu, Jing; Israelachvili, Jacob N

    2011-03-29

    Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple "modes" of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an "adaptive" role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) "boundary lubricant"--reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication; however, the system as a whole requires both HA and LUB to function optimally under all conditions.

  18. Advances on molecular mechanism of the adaptive evolution of Chiroptera (bats).

    PubMed

    Yunpeng, Liang; Li, Yu

    2015-01-01

    As the second biggest animal group in mammals, Chiroptera (bats) demonstrates many unique adaptive features in terms of flight, echolocation, auditory acuity, feeding habit, hibernation and immune defense, providing an excellent system for understanding the molecular basis of how organisms adapt to the living environments encountered. In this review, we summarize the researches on the molecular mechanism of the adaptive evolution of Chiroptera, especially the recent researches at the genome levels, suggesting a far more complex evolutionary pattern and functional diversity than previously thought. In the future, along with the increasing numbers of Chiroptera species genomes available, new evolutionary patterns and functional divergence will be revealed, which can promote the further understanding of this animal group and the molecular mechanism of adaptive evolution.

  19. 6-Benzylaminopurine inhibits growth of Monilinia fructicola and induces defense-related mechanism in peach fruit.

    PubMed

    Zhang, Yangyang; Zeng, Lizhen; Yang, Jiali; Zheng, Xiaodong; Yu, Ting

    2015-11-15

    This study demonstrated the inhibitory effect of 6-benzylaminopurine (BAP), the first generation synthetic cytokinin, on the invasion of Monilinia fructicola in peach fruit and the possible mechanism involved for the first time. Our results suggested that BAP treatment had a 63% lower disease incidence and approximately 10 times lower lesion diameter compared to the control throughout the incubation period. In vitro BAP showed a direct inhibitory effect on M. fructicola spore germination. BAP could prevent fruit texture deterioration and protect the cell membrane from oxidative stress, while no adverse effects were observed on fruit quality maintenance. Analysis of defense-related enzymes activities indicated that the use of BAP induced higher specific polyphenol oxidase and peroxidase activities which triggered stronger host defensive responses. Thus, our results verified the proposed mechanism of BAP in controlling M. fructicola by direct inhibitory effect, delay peach senescence and activation of defensive enzymes.

  20. Autophagy is an inflammation-related defensive mechanism against disease.

    PubMed

    Joven, Jorge; Guirro, Maria; Mariné-Casadó, Roger; Rodríguez-Gallego, Esther; Menéndez, Javier A

    2014-01-01

    The inflammatory response is an energy-intensive process. Consequently, metabolism is closely associated with immune function. The autophagy machinery plays a role in metabolism by providing energy but may also be used to attack invading pathogens (xenophagy). The autophagy machinery may function to protect against not only the threats of infection but also the threats of the host's own response acting on the central immunological tolerance and the negative regulation of innate and inflammatory signaling. The balance between too little and too much autophagy is critical for the survival of immune cells because autophagy is linked to type 2-cell death programmed necrosis and apoptosis. Changes in inflammatory cells are driven by extracellular signals; however, the mechanisms by which cytokines mediate autophagy regulation and govern immune cell function remain unknown. Certain cytokines increase autophagy, whereas others inhibit autophagy. The relationship between autophagy and inflammation is also important in the pathogenesis of metabolic, non-communicable diseases. Inflammation per se is not the cause of obesity-associated diseases, but it is secondary to both the positive energy balance and the specific cellular responses. In metabolic tissues, the suppression of autophagy increases inflammation with the overexpression of cytokines, resulting in an activation of autophagy. The physiological role of these apparently contradictory findings remains uncertain but exemplifies future challenges in the therapeutic modulation of autophagy in the management of disease.

  1. Learning to Recognize Ego Defense Mechanisms: Results of a Structured Teaching Experience for Psychiatric Residents

    ERIC Educational Resources Information Center

    Beresford, Thomas P.

    2005-01-01

    Objective: Ego defense mechanism (EDM) recognition can offer a powerful and practical tool in clinical psychiatry. However, recognition skill learning can be difficult to assess and may account for the lack of formal EDM recognition training in residency courses. Method: This study hypothesized that mean test scores would increase significantly…

  2. Effects of Sex, Social Desirability, and Birth Order on the Defense Mechanisms Inventory.

    ERIC Educational Resources Information Center

    Dudley, Gary E.

    1978-01-01

    Investigated effects of sex difference, social desirability instructions, and birth order of respondents on defense mechanisms inventory (DMI). Sex difference was found in projection only. Social desirability effects were found in turning-against-others, projection, principalization, and reversal. Thus, an interpretive caution is in order…

  3. Psychogenic non-epileptic seizures: so-called psychiatric comorbidity and underlying defense mechanisms

    PubMed Central

    Beghi, Massimiliano; Negrini, Paola Beffa; Perin, Cecilia; Peroni, Federica; Magaudda, Adriana; Cerri, Cesare; Cornaggia, Cesare Maria

    2015-01-01

    In Diagnostic and Statistical Manual of Mental Disorders, fifth edition, psychogenic non-epileptic seizures (PNES) do not have a unique classification as they can be found within different categories: conversion, dissociative, and somatization disorders. The ICD-10, instead, considers PNES within dissociative disorders, merging the dissociative disorders and conversion disorders, although the underlying defense mechanisms are different. The literature data show that PNES are associated with cluster B (mainly borderline) personality disorders and/or to people with depressive or anxiety disorders. Defense mechanisms in patients with PNES with a prevalence of anxious/depressive symptoms are of “neurotic” type; their goal is to lead to a “split”, either vertical (dissociation) or horizontal (repression). The majority of patients with this type of PNES have alexithymia traits, meaning that they had difficulties in feeling or perceiving emotions. In subjects where PNES are associated with a borderline personality, in which the symbolic function is lost, the defense mechanisms are of a more archaic nature (denial). PNES with different underlying defense mechanisms have different prognoses (despite similar severity of PNES) and need usually a different treatment (pharmacological or psychological). Thus, it appears superfluous to talk about psychiatric comorbidity, since PNES are a different symptomatic expression of specific psychiatric disorders. PMID:26491330

  4. DNA DAMAGE REPAIR AND CELL CYCLE CONTROL: A NATURAL BIO-DEFENSE MECHANISM

    EPA Science Inventory

    DNA DAMAGE REPAIR AND CELL CYCLE CONTROL: A natural bio-defense mechanism
    Anuradha Mudipalli.

    Maintenance of genetic information, including the correct sequence of nucleotides in DNA, is essential for replication, gene expression, and protein synthesis. DNA lesions onto...

  5. Brief Report: The Defense Mechanisms of Homophobic Adolescent Males--A Descriptive Discriminant Analysis

    ERIC Educational Resources Information Center

    Lewis, Andrew J.; White, Jennifer

    2009-01-01

    The study examined the role of defense mechanisms in homophobic attitudes of older male adolescents aged 17-18 years. A cross-sectional survey collected data from final year high school students (N = 86) attending an all male school in a regional centre in Victoria, Australia. The school was identified by teachers as having a problematic culture…

  6. Differences between matched heterosexual and non-heterosexual college students on defense mechanisms and psychopathological symptoms.

    PubMed

    Biernbaum, Mark A; Ruscio, Michele

    2004-01-01

    Differences between heterosexual and non-heterosexual college students on measures of defense mechanisms and psychopathological symptoms were examined. Fifty-six (28 heterosexual, 28 non-heterosexual) subjects were drawn from a larger study of college student adjustment. Non-heterosexual subjects were matched to a heterosexual peer on several demographic variables as well as on attachment security/insecurity. Differences between the two groups on the Defense Mechanism Inventory and the Brief Symptom Inventory were tested. Contrary to traditional psychoanalytic conceptions of homosexuality, no differences were found between the two groups on any subscale of the Defense Mechanism Inventory, thereby repudiating one important aspect of traditional psychoanalytic theories on the development of homosexuality. Non-heterosexual students reported significantly higher levels of anxiety, depression, somaticization, paranoid ideation, general symptom severity, and suicidal ideation. These students appear to be at increased risk for psychopathology and suicidal ideation, despite similar defense profiles, when compared to matched heterosexual peers. Additional research is needed to determine the origins of this increased risk, and comprehensive and targeted prevention and intervention programs must be established to ameliorate such risks.

  7. Attachment style and defense mechanisms in parents who abuse their children.

    PubMed

    Cramer, Phebe; Kelly, Francis D

    2010-09-01

    Adult attachment style, defense mechanisms, and personal history of abuse was studied in a group of abusive parents. As a group, these parents made unusually high use of the defense of denial; this was especially true of those with a Fearful attachment style. However, the use of Identification was characteristic of those with a Preoccupied attachment style. Further, personal abuse history was related to adult attachment style. Those who reported having been abused as a child were less likely to have a Secure attachment style, and a history of physical or sexual abuse was associated with a Preoccupied style. In general, these findings support the deactivating/hyperactivating defensive theory of Mikulincer et al (Emotion Regulation in Couples and Families: Pathways to Dysfunction and Health. 2006; pp 77-99. Washington (WA): American Psychological Association).

  8. Convergent evolution of defense mechanisms in oribatid mites (Acari, Oribatida) shows no "ghosts of predation past".

    PubMed

    Pachl, Patrick; Domes, Katja; Schulz, Garvin; Norton, Roy A; Scheu, Stefan; Schaefer, Ina; Maraun, Mark

    2012-11-01

    Oribatid mites are diverse and abundant terrestrial soil arthropods that are involved in decomposition of organic matter and nutrient cycling. As indicated by fossils starting from the Devonian, they evolved varied mechanisms and structures for defense from predators. We investigated four of these defensive structures (ptychoid body, hologastry, mineralization and opisthonotal glands) and used ancestral character state reconstruction to determine whether they evolved convergently and how many times this may have happened. Phylogenetic trees based on 18S rDNA were constructed for 42 oribatid mite species and two outgroup taxa using likelihood and Bayesian algorithms. The results suggest that at least three of the four defensive structures evolved convergently several times; for opisthonotal glands convergent evolution remains equivocal. This high level of convergence indicates that predation has been an important factor throughout the evolution of oribatid mites, contributing to morphological diversity and potentially also to species richness, as there are indications that some taxa radiated after the evolution of defense structures. Despite the ancientness of oribatid mites, defense structures seems to have been rarely lost, suggesting that they still are functional and necessary to reduce predation, rather than being 'ghosts of predation past'.

  9. Assessment of Defense Styles and Mechanisms in Iranian Patients Suffering from Obsessive Compulsive or Panic Disorders versus Normal Controls using Persian Version of Defense Style Questionnaire-40

    PubMed Central

    Shabanpour, Ruhollah; Zahiroddin, Ali Reza; Janbozorgi, Masoud

    2012-01-01

    Objective The aim of this study was to compare defense styles and mechanisms in adult patients suffering from obsessive-compulsive disorder (OCD), and panic disorder (PD) with normal subjects in Iran. Methods Defensive patterns of 22 patients with OCD, 28 patients with PD and those of 116 normal individuals (as a control group) were assessed using the Farsi version of Defense Style Questionnaire-40 (DSQ-40). The content validity of this questionnaire was done prior to the initiation of the present study. Results Both groups of patients with OCD or PD used more immature and less mature styles compared to the control group. No significant difference was observed in the use of neurotic style between the two groups. Conclusion It is suggested that immature defenses may have an important role in the pathogenesis of OCD and PD. PMID:23056115

  10. Exploring the association of ego defense mechanisms with problematic internet use in a Pakistani medical school.

    PubMed

    Waqas, Ahmed; Rehman, Abdul; Malik, Aamenah; Aftab, Ramsha; Allah Yar, Aroosa; Allah Yar, Arooj; Rai, Aitzaz Bin Sultan

    2016-09-30

    The present study was designed to analyze association between problematic internet use and use of ego defense mechanisms in medical students. This cross-sectional study was undertaken at CMH Lahore Medical College (CMH LMC) in Lahore, Pakistan from 1st March, 2015 to 30th May, 2015. 522 medical and dental students were included in the study. The questionnaire consisted of three sections: a) demographic characteristics of respondent b) the Defense Style Questionnaire-40 (DSQ-40) and c) the Internet Addiction Test (IAT). All data were analyzed in SPSS v20. Chi square, Independent sample t test and One Way ANOVA were run to analyze association of different variables with scores on IAT. Multiple regression analysis was used to delineate ego defenses as predictors of problematic internet use. A total of 32 (6.1%) students reported severe problems with internet usage. Males had higher scores on IAT i.e had more problematic use of internet. Scores on internet addiction test (IAT) were negatively associated with sublimation and positively associated with projection, denial, autistic fantasy, passive aggression and displacement. There was a high prevalence of problematic use of internet among medical and dental students. It had significant associations with several defense mechanisms.

  11. Exploring the association of ego defense mechanisms with problematic internet use in a Pakistani medical school.

    PubMed

    Waqas, Ahmed; Rehman, Abdul; Malik, Aamenah; Aftab, Ramsha; Allah Yar, Aroosa; Allah Yar, Arooj; Rai, Aitzaz Bin Sultan

    2016-09-30

    The present study was designed to analyze association between problematic internet use and use of ego defense mechanisms in medical students. This cross-sectional study was undertaken at CMH Lahore Medical College (CMH LMC) in Lahore, Pakistan from 1st March, 2015 to 30th May, 2015. 522 medical and dental students were included in the study. The questionnaire consisted of three sections: a) demographic characteristics of respondent b) the Defense Style Questionnaire-40 (DSQ-40) and c) the Internet Addiction Test (IAT). All data were analyzed in SPSS v20. Chi square, Independent sample t test and One Way ANOVA were run to analyze association of different variables with scores on IAT. Multiple regression analysis was used to delineate ego defenses as predictors of problematic internet use. A total of 32 (6.1%) students reported severe problems with internet usage. Males had higher scores on IAT i.e had more problematic use of internet. Scores on internet addiction test (IAT) were negatively associated with sublimation and positively associated with projection, denial, autistic fantasy, passive aggression and displacement. There was a high prevalence of problematic use of internet among medical and dental students. It had significant associations with several defense mechanisms. PMID:27504797

  12. Increased proliferation and decreased membrane permeability as defense mechanisms of Fusobacterium nucleatum against human neutrophilic peptide-1.

    PubMed

    Keskin, Mutlu; Könönen, Eija; Söderling, Eva; Isik, Gülden; Firatli, Erhan; Uitto, Veli-Jukka; Gürsoy, Ulvi Kahraman

    2014-12-01

    Human neutrophilic peptides (HNPs) constitute a class of host defense molecules, which contribute to the non-oxidative killing of bacteria and other microorganisms. Since the adaptability is crucial to bacterial survival in changing environments, it is of interest to know how Fusobacterium nucleatum, the major bridge organism connecting early and late colonizers in dental biofilms, defends itself against HNPs. This study aimed to examine the planktonic growth, membrane permeability, and biofilm formation characteristics as defense mechanisms of F. nucleatum against HNP-1. In all experiments, the type strain of F. nucleatum (ssp. nucleatum ATCC 25586) and two clinical strains (ssp. nucleatum AHN 9508 and ssp. polymorphum AHN 9910) were used. Planktonic growth (measured in colony forming units), capsular polysaccharide production (visualized by Ziehl-Neelsen stain), membrane permeability (demonstrated as N-phenyl-1-naphthylamine uptake), biofilm formation, and established biofilm development (measured as total mass and polysaccharide levels) were analyzed in the presence of 0 μg/ml (control), 1 μg/ml, 5 μg/ml, and 10 μg/ml of HNP-1. Planktonic growth of the strains AHN 9508 and ATCC 25586 were significantly (p<0.05) increased in the presence of HNP-1, while their membrane permeability decreased (p<0.005) in the planktonic form. HNP-1 decreased the biofilm formation of the strains ATCC 25586 and AHN 9910, whereas it increased the growth of the strain AHN 9508 in established biofilms. Capsule formation and polysaccharide production were not observed in any strain. We conclude that the inhibition of the membrane permeability and the increase in planktonic and established biofilm growth could act as bacterial defense mechanisms against neutrophilic defensins. In addition, this strain-dependent survival ability against HNP-1 may explain the variation in the virulence of different F. nucleatum strains.

  13. Solution-adaptive finite element method in computational fracture mechanics

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Bass, J. M.; Spradley, L. W.

    1993-01-01

    Some recent results obtained using solution-adaptive finite element method in linear elastic two-dimensional fracture mechanics problems are presented. The focus is on the basic issue of adaptive finite element method for validating the applications of new methodology to fracture mechanics problems by computing demonstration problems and comparing the stress intensity factors to analytical results.

  14. Parallel Adaptive Multi-Mechanics Simulations using Diablo

    SciTech Connect

    Parsons, D; Solberg, J

    2004-12-03

    Coupled multi-mechanics simulations (such as thermal-stress and fluidstructure interaction problems) are of substantial interest to engineering analysts. In addition, adaptive mesh refinement techniques present an attractive alternative to current mesh generation procedures and provide quantitative error bounds that can be used for model verification. This paper discusses spatially adaptive multi-mechanics implicit simulations using the Diablo computer code. (U)

  15. General beliefs about the world as defensive mechanisms against death anxiety.

    PubMed

    Hui, Victoria Ka-Ying; Bond, Michael Harris; Ng, Timmy Sze Wing

    Death ideation and death anxiety represent the cognitive and affective dimensions of death attitudes, respectively. General beliefs about the world are proposed to be useful defensive mechanisms protecting persons against the death anxiety provoked by death ideation. SEM is employed to test the proposed mediation model, using a sample of 133 Hong Kong Chinese university students. Results showed that death ideation was significantly and inversely linked to belief in social cynicism, reward for application, and fate control. Moreover, higher levels of belief in fate control and lower levels of religiosity predicted greater death anxiety. Only belief in fate control partially mediated the relationship between death ideation and death anxiety. Discussion focused on how social axioms serve as useful defensive mechanisms against death anxiety.

  16. Do common mechanisms of adaptation mediate color discrimination and appearance? Contrast adaptation

    NASA Astrophysics Data System (ADS)

    Hillis, James M.; Brainard, David H.

    2007-08-01

    Are effects of background contrast on color appearance and sensitivity controlled by the same mechanism of adaptation? We examined the effects of background color contrast on color appearance and on color-difference sensitivity under well-matched conditions. We linked the data using Fechner's hypothesis that the rate of apparent stimulus change is proportional to sensitivity and examined a family of parametric models of adaptation. Our results show that both appearance and discrimination are consistent with the same mechanism of adaptation.

  17. Do common mechanisms of adaptation mediate color discrimination and appearance? Contrast adaptation.

    PubMed

    Hillis, James M; Brainard, David H

    2007-08-01

    Are effects of background contrast on color appearance and sensitivity controlled by the same mechanism of adaptation? We examined the effects of background color contrast on color appearance and on color-difference sensitivity under well-matched conditions. We linked the data using Fechner's hypothesis that the rate of apparent stimulus change is proportional to sensitivity and examined a family of parametric models of adaptation. Our results show that both appearance and discrimination are consistent with the same mechanism of adaptation.

  18. Proteomic investigation of the effect of salicylic acid on Arabidopsis seed germination and establishment of early defense mechanisms.

    PubMed

    Rajjou, Loïc; Belghazi, Maya; Huguet, Romain; Robin, Caroline; Moreau, Adrien; Job, Claudette; Job, Dominique

    2006-07-01

    The influence of salicylic acid (SA) on elicitation of defense mechanisms in Arabidopsis (Arabidopsis thaliana) seeds and seedlings was assessed by physiological measurements combined with global expression profiling (proteomics). Parallel experiments were carried out using the NahG transgenic plants expressing the bacterial gene encoding SA hydroxylase, which cannot accumulate the active form of this plant defense elicitor. SA markedly improved germination under salt stress. Proteomic analyses disclosed a specific accumulation of protein spots regulated by SA as inferred by silver-nitrate staining of two-dimensional gels, detection of carbonylated (oxidized) proteins, and neosynthesized proteins with [35S]-methionine. The combined results revealed several processes potentially affected by SA. This molecule enhanced the reinduction of the late maturation program during early stages of germination, thereby allowing the germinating seeds to reinforce their capacity to mount adaptive responses in environmental water stress. Other processes affected by SA concerned the quality of protein translation, the priming of seed metabolism, the synthesis of antioxidant enzymes, and the mobilization of seed storage proteins. All the observed effects are likely to improve seed vigor. Another aspect revealed by this study concerned the oxidative stress entailed by SA in germinating seeds, as inferred from a characterization of the carbonylated (oxidized) proteome. Finally, the proteomic data revealed a close interplay between abscisic signaling and SA elicitation of seed vigor.

  19. Investigating Aggressive Styles and Defense Mechanisms in Bipolar Patients and in their Parents.

    PubMed

    Bragazzi, Nicola Luigi; Pezzoni, Franca; Del Puente, Giovanni

    2014-11-01

    Bipolar disorder (BD) is a very common mental health disorder, whose etiology concerning aggressive styles and defense mechanisms is still poorly known despite the efforts dedicated to develop psychological and biological theories. After obtaining written signed informed consent, this study will recruit inpatients with a clinical diagnosis of BD, based on Structured Clinical Interview and the Diagnostic and Statistical Manual of Mental Disorders criteria, and their parents. The Bus-Perry Aggression Questionnaire, the Defense Style Questionnaire 40, the Symptom check list SCL-90-R, developed by DeRogatis will be administered to the participants, together with a semi-structured questionnaire concerning demographic data (age, gender, employment, education) and only for the patients clinical information (onset year of the disorder, presence of co-morbidities, alcohol and drug use, suicide tendencies, kind of treatment). All the questionnaires are in the Italian validated version. The successful completion of this study will shed light on the relationship between aggressive styles and defensive mechanisms in bipolar inpatients and in their parents, helping the clinicians to develop ad hoc psychological interventions.

  20. Priming by Rhizobacterium Protects Tomato Plants from Biotrophic and Necrotrophic Pathogen Infections through Multiple Defense Mechanisms

    PubMed Central

    Ahn, Il-Pyung; Lee, Sang-Woo; Kim, Min Gab; Park, Sang-Ryeol; Hwang, Duk-Ju; Bae, Shin-Chul

    2011-01-01

    A selected strain of rhizobacterium, Pseudomonas putida strain LSW17S (LSW17S), protects tomato plants (Lycopersicon esculentum L. cv. Seokwang) from bacterial speck by biotrophic Pseudomonas syringae pv. tomato strain DC3000 (DC3000) and bacterial wilt by necrotrophic Ralstonia solanacearum KACC 10703 (Rs10703). To investigate defense mechanisms induced by LSW17S in tomato plants, transcription patterns of pathogenesis-related (PR) genes and H2O2 production were analyzed in plants treated with LSW17S and subsequent pathogen inoculation. LSW17S alone did not induce transcriptions of employed PR genes in leaves and roots. DC3000 challenge following LSW17S triggered rapid transcriptions of PR genes and H2O2 production in leaves and roots. Catalase infiltration with DC3000 attenuated defense-related responses and resistance against DC3000 infection. Despite depriving H2O2 production and PR1b transcription by the same treatment, resistance against Rs10703 infection was not deterred significantly. H2O2 is indispensable for defense signaling and/or mechanisms primed by LSW17S and inhibition of bacterial speck, however, it is not involved in resistance against bacterial wilt. PMID:21710203

  1. Investigating Aggressive Styles and Defense Mechanisms in Bipolar Patients and in their Parents

    PubMed Central

    Bragazzi, Nicola Luigi; Pezzoni, Franca; Del Puente, Giovanni

    2014-01-01

    Bipolar disorder (BD) is a very common mental health disorder, whose etiology concerning aggressive styles and defense mechanisms is still poorly known despite the efforts dedicated to develop psychological and biological theories. After obtaining written signed informed consent, this study will recruit inpatients with a clinical diagnosis of BD, based on Structured Clinical Interview and the Diagnostic and Statistical Manual of Mental Disorders criteria, and their parents. The Bus-Perry Aggression Questionnaire, the Defense Style Questionnaire 40, the Symptom check list SCL-90-R, developed by DeRogatis will be administered to the participants, together with a semi-structured questionnaire concerning demographic data (age, gender, employment, education) and only for the patients clinical information (onset year of the disorder, presence of co-morbidities, alcohol and drug use, suicide tendencies, kind of treatment). All the questionnaires are in the Italian validated version. The successful completion of this study will shed light on the relationship between aggressive styles and defensive mechanisms in bipolar inpatients and in their parents, helping the clinicians to develop ad hoc psychological interventions. PMID:26973942

  2. Molecular Dynamics Simulation and Statistics Analysis Reveals the Defense Response Mechanism in Plants

    NASA Astrophysics Data System (ADS)

    Liu, Zhichao; Zhao, Yunjie; Zeng, Chen; Computational Biophysics Lab Team

    As the main protein of the bacterial flagella, flagellin plays an important role in perception and defense response. The newly discovered locus, FLS2, is ubiquitously expressed. FLS2 encodes a putative receptor kinase and shares many homologies with some plant resistance genes and even with some components of immune system of mammals and insects. In Arabidopsis, FLS2 perception is achieved by the recognition of epitope flg22, which induces FLS2 heteromerization with BAK1 and finally the plant immunity. Here we use both analytical methods such as Direct Coupling Analysis (DCA) and Molecular Dynamics (MD) Simulations to get a better understanding of the defense mechanism of FLS2. This may facilitate a redesign of flg22 or de-novo design for desired specificity and potency to extend the immune properties of FLS2 to other important crops and vegetables.

  3. Mechanism of bystander-blaming: defensive attribution, counterfactual thinking, and gender.

    PubMed

    Levy, Inna; Ben-David, Sarah

    2015-01-01

    Contemporary victimology recognizes that an understanding of the mechanism of blaming requires a comprehensive approach that includes the victim, the offender, and the bystander. However, most of the existing research on blaming focuses on the victim and the offender, ignoring the issue of bystander-blaming. This study highlights the bystander and investigates bystander-blaming by exploring some theoretical explanations, including counterfactual thinking, defensive attribution, and gender differences. The study included 363 young male and female participants, who read vignettes describing the behavior of the victim and the bystander in a rape scenario and answered questions regarding bystander-blaming. The results show that both counterfactual thinking and defensive attribution play a role in bystander-blaming. This article addresses the theoretical and practical implications of these findings.

  4. Essential Functional Modules for Pathogenic and Defensive Mechanisms in Candida albicans Infections

    PubMed Central

    Tsai, I-Chun; Lin, Che; Chuang, Yung-Jen

    2014-01-01

    The clinical and biological significance of the study of fungal pathogen Candida albicans (C. albicans) has markedly increased. However, the explicit pathogenic and invasive mechanisms of such host-pathogen interactions have not yet been fully elucidated. Therefore, the essential functional modules involved in C. albicans-zebrafish interactions were investigated in this study. Adopting a systems biology approach, the early-stage and late-stage protein-protein interaction (PPI) networks for both C. albicans and zebrafish were constructed. By comparing PPI networks at the early and late stages of the infection process, several critical functional modules were identified in both pathogenic and defensive mechanisms. Functional modules in C. albicans, like those involved in hyphal morphogenesis, ion and small molecule transport, protein secretion, and shifts in carbon utilization, were seen to play important roles in pathogen invasion and damage caused to host cells. Moreover, the functional modules in zebrafish, such as those involved in immune response, apoptosis mechanisms, ion transport, protein secretion, and hemostasis-related processes, were found to be significant as defensive mechanisms during C. albicans infection. The essential functional modules thus determined could provide insights into the molecular mechanisms of host-pathogen interactions during the infection process and thereby devise potential therapeutic strategies to treat C. albicans infection. PMID:24757665

  5. Mechanics and applications of pressure adaptive honeycomb

    NASA Astrophysics Data System (ADS)

    Vos, Roelof

    A novel adaptive aerostructure is presented that relies on certified aerospace materials and can therefore be applied in conventional passenger aircraft. This structure consists of a honeycomb material which' cells extend over a significant length perpendicular to the plane of the cells. Each of the cells contains an inelastic pouch (or bladder) that forms a circular tube when the cell forms a perfect hexagon. By changing the cell differential pressure (CDP) the stiffness of the honeycomb can be altered. Using an external force or the elastic force within the honeycomb material, the honeycomb can be deformed such that the cells deviate from their perfect-hexagonal shape. It can be shown that by increasing the CDP, the structure eventually returns to a perfect hexagon. By doing so, a fully embedded pneumatic actuator is created that can perform work and substitute conventional low-bandwidth flight control actuators. It is shown that two approaches can be taken to regulate the stiffness of this embedded actuator: (1) The first approach relies on the pouches having a fixed amount of air in them and stiffness is altered by a change in ambient pressure. Coupled to the ambient pressure-altitude cycle that aircraft encounter during each flight, this approach yields a true adaptive aerostructure that operates independently of pilot input and is controlled solely by the altitude the aircraft is flying at. (2) The second approach relies on a controlled constant CDP. This CDP could be supplied from one of the compressor stages of the engine as a form of bleed air. Because of the air-tight pouches there would essentially be no mass flow, meaning engine efficiency would not be significantly affected due to this application. By means of a valve system the pilot could have direct control over the pressure and, consequently, the stiffness of the structure. This allows for much higher CDPs (on the order of 1MPa) than could physically be achieved by relying on the ambient pressure

  6. Adaptation of the tendon to mechanical usage.

    PubMed

    Reeves, N D

    2006-01-01

    Tendons primarily function as contractile force transmitters, but their mechanical properties may change dependent upon their level of mechanical usage. Using an ultrasound-based technique we have assessed tendon mechanical properties in vivo in a number of conditions representing different levels of mechanical usage. Ageing alters tendon mechanical properties; stiffness and modulus were lower in older adults by 10 and 14%, respectively, compared to young adults. Increased levels of exercise loading in old age can however partly reverse this process, as tendon stiffness and modulus were found to increase by 65 and 69%, respectively. Complete unloading due to bed rest or spinal cord injury both reduce tendon stiffness and modulus, however, only chronic unloading due to spinal cord injury seems to cause tendon atrophy. Alterations in tendon mechanical properties due to changes in the levels loading have implications for the speed of force transmission, the muscle's operating range and the likelihood of tendon strain injury.

  7. Of Amoebae and Men: Extracellular DNA Traps as an Ancient Cell-Intrinsic Defense Mechanism

    PubMed Central

    Zhang, Xuezhi; Soldati, Thierry

    2016-01-01

    Since the discovery of the formation of DNA-based extracellular traps (ETs) by neutrophils as an innate immune defense mechanism (1), hundreds of articles describe the involvement of ETs in physiological and pathological human and animal conditions [reviewed in Ref. (2), and the previous Frontiers Research Topic on NETosis: http://www.frontiersin.org/books/NETosis_At_the_Intersection_of_Cell_Biology_Microbiology_and_Immunology/195]. Interestingly, a few reports reveal that ETs can be formed by immune cells of more ancient organisms, as far back as the common ancestor of vertebrates and invertebrates (3). Recently, we reported that the Sentinel cells of the multicellular slug of the social amoeba Dictyostelium discoideum also produce ETs to trap and kill slug-invading bacteria [see Box 1; and Figure 1 Ref. (4)]. This is a strong evidence that DNA-based cell-intrinsic defense mechanisms emerged much earlier than thought, about 1.3 billion years ago. Amazingly, using extrusion of DNA as a weapon to capture and kill uningestable microbes has its rationale. During the emergence of multicellularity, a primitive innate immune system developed in the form of a dedicated set of specialized phagocytic cells. This professionalization of immunity allowed the evolution of sophisticated defense mechanisms including the sacrifice of a small set of cells by a mechanism related to NETosis. This altruistic behavior likely emerged in steps, starting from the release of “dispensable” mitochondrial DNA by D. discoideum Sentinel cells. Grounded in this realization, one can anticipate that in the near future, many more examples of the invention and fine-tuning of ETs by early metazoan ancestors will be identified. Consequently, it can be expected that this more complete picture of the evolution of ETs will impact our views of the involvement and pathologies linked to ETs in human and animals. PMID:27458458

  8. Of Amoebae and Men: Extracellular DNA Traps as an Ancient Cell-Intrinsic Defense Mechanism.

    PubMed

    Zhang, Xuezhi; Soldati, Thierry

    2016-01-01

    Since the discovery of the formation of DNA-based extracellular traps (ETs) by neutrophils as an innate immune defense mechanism (1), hundreds of articles describe the involvement of ETs in physiological and pathological human and animal conditions [reviewed in Ref. (2), and the previous Frontiers Research Topic on NETosis: http://www.frontiersin.org/books/NETosis_At_the_Intersection_of_Cell_Biology_Microbiology_and_Immunology/195]. Interestingly, a few reports reveal that ETs can be formed by immune cells of more ancient organisms, as far back as the common ancestor of vertebrates and invertebrates (3). Recently, we reported that the Sentinel cells of the multicellular slug of the social amoeba Dictyostelium discoideum also produce ETs to trap and kill slug-invading bacteria [see Box 1; and Figure 1 Ref. (4)]. This is a strong evidence that DNA-based cell-intrinsic defense mechanisms emerged much earlier than thought, about 1.3 billion years ago. Amazingly, using extrusion of DNA as a weapon to capture and kill uningestable microbes has its rationale. During the emergence of multicellularity, a primitive innate immune system developed in the form of a dedicated set of specialized phagocytic cells. This professionalization of immunity allowed the evolution of sophisticated defense mechanisms including the sacrifice of a small set of cells by a mechanism related to NETosis. This altruistic behavior likely emerged in steps, starting from the release of "dispensable" mitochondrial DNA by D. discoideum Sentinel cells. Grounded in this realization, one can anticipate that in the near future, many more examples of the invention and fine-tuning of ETs by early metazoan ancestors will be identified. Consequently, it can be expected that this more complete picture of the evolution of ETs will impact our views of the involvement and pathologies linked to ETs in human and animals. PMID:27458458

  9. Defense mechanisms of Solanum tuberosum L. in response to attack by plant-pathogenic bacteria.

    PubMed

    Poiatti, Vera A D; Dalmas, Fernando R; Astarita, Leandro V

    2009-01-01

    The natural resistance of plants to disease is based not only on preformed mechanisms, but also on induced mechanisms. The defense mechanisms present in resistant plants may also be found in susceptible ones. This study attempted to analyze the metabolic alterations in plants of the potato Solanum tuberosum L. cv. Agata that were inoculated with the incompatible plant-pathogenic bacteria X. axonopodis and R. solanacearum, and the compatible bacterium E. carotovora. Levels of total phenolic compounds, including the flavonoid group, and the activities of polyphenol oxidase (PPO) and peroxidase (POX) were evaluated. Bacteria compatibility was evaluated by means of infiltration of tubers. The defense response was evaluated in the leaves of the potato plants. Leaves were inoculated depending on their number and location on the stem. Multiple-leaf inoculation was carried out on basal, intermediate, and apical leaves, and single inoculations on intermediate leaves. Leaves inoculated with X. axonopodis and with R. solanacearum showed hypersensitive responses within 24 hours post-inoculation, whereas leaves inoculated with E. carotovora showed disease symptoms. Therefore, the R. solanacearum isolate used in the experiments did not exhibit virulence to this potato cultivar. Regardless of the bacterial treatments, the basal leaves showed higher PPO and POX activities and lower levels of total phenolic compounds and flavonoids, compared to the apical leaves. However, basal and intermediate leaves inoculated with R. solanacearum and X. axonopodis showed increases in total phenolic compounds and flavonoid levels. In general, multiple-leaf inoculation showed the highest levels of total phenolics and flavonoids, whereas the single inoculations resulted in the highest increase in PPO activity. The POX activity showed no significant difference between single- and multiple-leaf inoculations. Plants inoculated with E. carotovora showed no significant increase in defense mechanisms

  10. An empirically derived hierarchy of adaptive mechanisms and its usefulness as a potential diagnostic axis.

    PubMed

    Vaillant, G E

    1985-01-01

    This report empirically examines the utility of the model of ego mechanisms of defense to explain psychological resilience in 307 middle aged men with socially disadvantaged childhoods. The sample has been prospectively followed for forty years. The model arranges defense mechanisms along a hierarchy reflecting severity of psychopathology and hypothetical immaturity. The value of this hierarchy of defenses in relation to diagnosis is discussed.

  11. Endurance Training and Glutathione-Dependent Antioxidant Defense Mechanism in Heart of the Diabetic Rats

    PubMed Central

    Gül, Mustafa; Atalay, Mustafa; Hänninen, Osmo

    2003-01-01

    Regular physical exercise beneficially influences cardiac antioxidant defenses in normal rats. The aim of this study was to test whether endurance training can strengthen glutathione-dependent antioxidant defense mechanism and decrease lipid peroxidation in heart of the streptozotocin-induced diabetic rats. Redox status of glutathione in blood of diabetic rats in response to training and acute exercise was also examined. Eight weeks of treadmill training increased the endurance in streptozotocin-induced diabetic rats. It did not affect glutathione level in heart tissue at rest and also after exercise. On the other hand, endurance training decreased glutathione peroxidase activity in heart, while glutathione reductase and glutathione S-transferase activities were not affected either by acute exhaustive exercise or endurance training. Reduced and oxidized glutathione levels in blood were not affected by either training or acute exercise. Conjugated dienes levels in heart tissue were increased by acute exhaustive exercise and also 8 weeks treadmill training. Longer duration of exhaustion in trained group may have contributed to the increased conjugated dienes levels in heart after acute exercise. Our results suggest that endurance type exercise may make heart more susceptible to oxidative stress. Therefore it may be wise to combine aerobic exercise with insulin treatment to prevent its adverse effects on antioxidant defense in heart in patients with diabetes mellitus. PMID:24616611

  12. [Defense mechanism to prevent ectopic activation of pancreatic digestive enzymes under physiological conditions and its breakdown in acute pancreatitis].

    PubMed

    Kaku, Midori; Otsuko, Makoto

    2004-11-01

    Independent of the etiology, acute pancreatitis is associated with significant morbidity and the potential for mortality. In most patients, acute pancreatitis follows an uncomplicated or mild course. Recent studies in hereditary pancreatitis have clearly revealed that trypsin is the key enzyme at the onset of pancreatitis. However, there are several defense mechanisms to prevent ectopic activation of trypsin under physiological conditions. If the defense mechanisms failed or activation of trypsin occurred over defense ability, trypsin would activate other digestive enzymes and self-digestion of the pancreas would occur.

  13. Expression proteomics identifies biochemical adaptations and defense responses in transgenic plants with perturbed polyamine metabolism.

    PubMed

    Franceschetti, Marina; Perry, Barry; Thompson, Benjamin; Hanfrey, Colin; Michael, Anthony J

    2004-10-22

    Soluble proteins from leaves of transgenic tobacco plants with perturbed polyamine metabolism, caused by S-adenosylmethionine decarboxylase overexpression, were analysed by comparative proteomics. A group of proteins was found to be increasingly repressed, in parallel with the degree of polyamine perturbation, in each of the three independent transgenic lines. These were identified as isoforms of chloroplast ribonucleoproteins, known to be involved in chloroplast mRNA stability, processing and translation. Another group of eight proteins strongly induced in the most metabolically perturbed line was identified as multiple, uncharacterised isoforms of the defense protein PR-1, a known marker for systemic acquired resistance.

  14. Guardian of the Human Genome: Host Defense Mechanisms against LINE-1 Retrotransposition

    PubMed Central

    Ariumi, Yasuo

    2016-01-01

    Long interspersed element type 1 (LINE-1, L1) is a mobile genetic element comprising about 17% of the human genome, encoding a newly identified ORF0 with unknown function, ORF1p with RNA-binding activity and ORF2p with endonuclease and reverse transcriptase activities required for L1 retrotransposition. L1 utilizes an endonuclease (EN) to insert L1 cDNA into target DNA, which induces DNA double-strand breaks (DSBs). The ataxia-telangiectasia mutated (ATM) is activated by DSBs and subsequently the ATM-signaling pathway plays a role in regulating L1 retrotransposition. In addition, the host DNA repair machinery such as non-homologous end-joining (NHEJ) repair pathway is also involved in L1 retrotransposition. On the other hand, L1 is an insertional mutagenic agent, which contributes to genetic change, genomic instability, and tumorigenesis. Indeed, high-throughput sequencing-based approaches identified numerous tumor-specific somatic L1 insertions in variety of cancers, such as colon cancer, breast cancer, and hepatocellular carcinoma (HCC). In fact, L1 retrotransposition seems to be a potential factor to reduce the tumor suppressive property in HCC. Furthermore, recent study demonstrated that a specific viral-human chimeric transcript, HBx-L1, contributes to hepatitis B virus (HBV)-associated HCC. In contrast, host cells have evolved several defense mechanisms protecting cells against retrotransposition including epigenetic regulation through DNA methylation and host defense factors, such as APOBEC3, MOV10, and SAMHD1, which restrict L1 mobility as a guardian of the human genome. In this review, I focus on somatic L1 insertions into the human genome in cancers and host defense mechanisms against deleterious L1 insertions. PMID:27446907

  15. Guardian of the Human Genome: Host Defense Mechanisms against LINE-1 Retrotransposition.

    PubMed

    Ariumi, Yasuo

    2016-01-01

    Long interspersed element type 1 (LINE-1, L1) is a mobile genetic element comprising about 17% of the human genome, encoding a newly identified ORF0 with unknown function, ORF1p with RNA-binding activity and ORF2p with endonuclease and reverse transcriptase activities required for L1 retrotransposition. L1 utilizes an endonuclease (EN) to insert L1 cDNA into target DNA, which induces DNA double-strand breaks (DSBs). The ataxia-telangiectasia mutated (ATM) is activated by DSBs and subsequently the ATM-signaling pathway plays a role in regulating L1 retrotransposition. In addition, the host DNA repair machinery such as non-homologous end-joining (NHEJ) repair pathway is also involved in L1 retrotransposition. On the other hand, L1 is an insertional mutagenic agent, which contributes to genetic change, genomic instability, and tumorigenesis. Indeed, high-throughput sequencing-based approaches identified numerous tumor-specific somatic L1 insertions in variety of cancers, such as colon cancer, breast cancer, and hepatocellular carcinoma (HCC). In fact, L1 retrotransposition seems to be a potential factor to reduce the tumor suppressive property in HCC. Furthermore, recent study demonstrated that a specific viral-human chimeric transcript, HBx-L1, contributes to hepatitis B virus (HBV)-associated HCC. In contrast, host cells have evolved several defense mechanisms protecting cells against retrotransposition including epigenetic regulation through DNA methylation and host defense factors, such as APOBEC3, MOV10, and SAMHD1, which restrict L1 mobility as a guardian of the human genome. In this review, I focus on somatic L1 insertions into the human genome in cancers and host defense mechanisms against deleterious L1 insertions. PMID:27446907

  16. Contrasting Potato Foliage and Tuber Defense Mechanisms against the Late Blight Pathogen Phytophthora infestans

    PubMed Central

    Bradeen, James M.

    2016-01-01

    The late blight pathogen Phytophthora infestans can attack both potato foliage and tubers. When inoculated with P. infestans, foliage of nontransformed ‘Russet Burbank’ (WT) develops late blight disease while that of transgenic ‘Russet Burbank’ line SP2211 (+RB) does not. We compared the foliar transcriptome responses of these two lines to P. infestans inoculation using an RNA-seq approach. A total of 515 million paired end RNA-seq reads were generated, representing the transcription of 29,970 genes. We also compared the differences and similarities of defense mechanisms against P. infestans in potato foliage and tubers. Differentially expressed genes, gene groups and ontology bins were identified to show similarities and differences in foliage and tuber defense mechanisms. Our results suggest that R gene dosage and shared biochemical pathways (such as ethylene and stress bins) contribute to RB-mediated incompatible potato-P. infestans interactions in both the foliage and tubers. Certain ontology bins such as cell wall and lipid metabolisms are potentially organ-specific. PMID:27441721

  17. Hepatocyte-mediated cytotoxicity and host defense mechanisms in the alcohol-injured liver.

    PubMed

    McVicker, Benita L; Thiele, Geoffrey M; Tuma, Dean J; Casey, Carol A

    2014-09-01

    The consumption of alcohol is associated with many health issues including alcoholic liver disease (ALD). The natural history of ALD involves the development of steatosis, inflammation (steatohepatitis), fibrosis and cirrhosis. During the stage of steatohepatitis, the combination of inflammation and cellular damage can progress to a severe condition termed alcoholic hepatitis (AH). Unfortunately, the pathogenesis of AH remains uncharacterized. Some modulations have been identified in host defense and liver immunity mechanisms during AH that highlight the role of intrahepatic lymphocyte accumulation and associated inflammatory cytokine responses. Also, it is hypothesized that alcohol-induced injury to liver cells may significantly contribute to the aberrant lymphocytic distribution that is seen in AH. In particular, the regulation of lymphocytes by hepatocytes may be disrupted in the alcoholic liver resulting in altered immunologic homeostasis and perpetuation of disease. In recent studies, it was demonstrated that the direct killing of activated T lymphocytes by hepatocytes is facilitated by the asialoglycoprotein receptor (ASGPR). The ASGPR is a well-characterized glycoprotein receptor that is exclusively expressed by hepatocytes. This hepatic receptor is known for its role in the clearance of desialylated glycoproteins or cells, yet neither its physiological function nor its role in disease states has been determined. Interestingly, alcohol markedly impairs ASGPR function; however, the effect alcohol has on ASGPR-mediated cytotoxicity of lymphocytes remains to be elucidated. This review discusses the contribution of hepatocytes in immunological regulation and, importantly, how pathological effects of ethanol disrupt hepatocellular-mediated defense mechanisms.

  18. Contrasting Potato Foliage and Tuber Defense Mechanisms against the Late Blight Pathogen Phytophthora infestans.

    PubMed

    Gao, Liangliang; Bradeen, James M

    2016-01-01

    The late blight pathogen Phytophthora infestans can attack both potato foliage and tubers. When inoculated with P. infestans, foliage of nontransformed 'Russet Burbank' (WT) develops late blight disease while that of transgenic 'Russet Burbank' line SP2211 (+RB) does not. We compared the foliar transcriptome responses of these two lines to P. infestans inoculation using an RNA-seq approach. A total of 515 million paired end RNA-seq reads were generated, representing the transcription of 29,970 genes. We also compared the differences and similarities of defense mechanisms against P. infestans in potato foliage and tubers. Differentially expressed genes, gene groups and ontology bins were identified to show similarities and differences in foliage and tuber defense mechanisms. Our results suggest that R gene dosage and shared biochemical pathways (such as ethylene and stress bins) contribute to RB-mediated incompatible potato-P. infestans interactions in both the foliage and tubers. Certain ontology bins such as cell wall and lipid metabolisms are potentially organ-specific. PMID:27441721

  19. Trichoderma viride Laccase Plays a Crucial Role in Defense Mechanism against Antagonistic Organisms

    PubMed Central

    Divya, Lakshmanan; Sadasivan, C.

    2016-01-01

    Fungal laccases are involved in a variety of physiological functions such as delignification, morphogenesis, and parasitism. In addition to these functions, we suggest that fungal laccases are involved in defense mechanisms. When the laccase secreting Trichoderma viride was grown in the presence of a range of microorganisms including bacteria and fungi, laccase secretion was enhanced in response to antagonistic organisms alone. In addition, growth of antagonistic microbes was restricted by the secreting fungi. Besides, our study for the first time shows the inability of the secreting fungi (T. viride) to compete with antagonistic organism when laccase activity is inhibited, further emphasizing its involvement in rendering a survival advantage to the secreting organism. When laccase inhibitor was added to the media, the zone of inhibition exerted by the antagonist organism was more pronounced and consequently growth of T. viride was significantly restricted. Based on these observations we accentuate that, laccase plays an important role in defense mechanism and provides endurance to the organism when encountered with an antagonistic organism in its surrounding. PMID:27242756

  20. Trichoderma viride Laccase Plays a Crucial Role in Defense Mechanism against Antagonistic Organisms.

    PubMed

    Divya, Lakshmanan; Sadasivan, C

    2016-01-01

    Fungal laccases are involved in a variety of physiological functions such as delignification, morphogenesis, and parasitism. In addition to these functions, we suggest that fungal laccases are involved in defense mechanisms. When the laccase secreting Trichoderma viride was grown in the presence of a range of microorganisms including bacteria and fungi, laccase secretion was enhanced in response to antagonistic organisms alone. In addition, growth of antagonistic microbes was restricted by the secreting fungi. Besides, our study for the first time shows the inability of the secreting fungi (T. viride) to compete with antagonistic organism when laccase activity is inhibited, further emphasizing its involvement in rendering a survival advantage to the secreting organism. When laccase inhibitor was added to the media, the zone of inhibition exerted by the antagonist organism was more pronounced and consequently growth of T. viride was significantly restricted. Based on these observations we accentuate that, laccase plays an important role in defense mechanism and provides endurance to the organism when encountered with an antagonistic organism in its surrounding. PMID:27242756

  1. A generic mechanism for adaptive growth rate regulation.

    PubMed

    Furusawa, Chikara; Kaneko, Kunihiko

    2008-01-01

    How can a microorganism adapt to a variety of environmental conditions despite the existence of a limited number of signal transduction mechanisms? We show that for any growing cells whose gene expression fluctuate stochastically, the adaptive cellular state is inevitably selected by noise, even without a specific signal transduction network for it. In general, changes in protein concentration in a cell are given by its synthesis minus dilution and degradation, both of which are proportional to the rate of cell growth. In an adaptive state with a higher growth speed, both terms are large and balanced. Under the presence of noise in gene expression, the adaptive state is less affected by stochasticity since both the synthesis and dilution terms are large, while for a nonadaptive state both the terms are smaller so that cells are easily kicked out of the original state by noise. Hence, escape time from a cellular state and the cellular growth rate are negatively correlated. This leads to a selection of adaptive states with higher growth rates, and model simulations confirm this selection to take place in general. The results suggest a general form of adaptation that has never been brought to light--a process that requires no specific mechanisms for sensory adaptation. The present scheme may help explain a wide range of cellular adaptive responses including the metabolic flux optimization for maximal cell growth.

  2. Drought resistance in rice seedlings conferred by seed priming : role of the anti-oxidant defense mechanisms.

    PubMed

    Goswami, Alakananda; Banerjee, Rahul; Raha, Sanghamitra

    2013-10-01

    Seed priming is a method by which seeds are subjected to different stress conditions to impart stress adaptation in seedlings germinating and growing under stressful situations. Drought stress is a major reason behind failure of crops. We studied the effects of hydropriming, dehydration priming (induced by PEG), and osmopriming (induced by NaCl and KH(2)PO(4)) on subsequent germination, growth and anti-oxidant defense mechanisms of 2-week-old rice seedlings under continuing dehydration stress. Unprimed seeds grown in PEG showed significantly lower germination and growth along with significantly higher reactive oxygen species (ROS) and lipid peroxidation levels. Among the priming methods, 5 % PEG priming was found to be the best in terms of germination and growth rate along with the lowest amount of ROS and lipid peroxidation (malondialdehyde [MDA]) values. MDA levels were reduced significantly by all of the priming methods. Hence, reduction of lipid peroxidation may be a key factor underlying the drought tolerance produced by the priming treatments. Glutathione peroxidase (GPX) activity seemed to bear an excellent correlation with oxidative stress resistance through seed priming. The PEG priming produced minimum peroxidative damage and superior germination and growth rate along with efficient GPX activity, overexpressed MnSOD and maintenance of HSP70 expression in normal as well as in drought condition. Therefore, in PEG-primed seeds the existence of robust protective mechanisms is definitely indicated.

  3. Mechanisms underlying neglect recovery after prism adaptation.

    PubMed

    Serino, Andrea; Angeli, Valentina; Frassinetti, Francesca; Làdavas, Elisabetta

    2006-01-01

    Prism adaptation (PA) has been demonstrated to be effective in improving hemispatial neglect. However not all patients seem to benefit from this procedure. Thus, the objective of the present work is to provide behavioural and neuroanatomical predictors of recovery by exploring the reorganization of low-order visuo-motor behaviour and high-order visuo-spatial representation induced by PA. To this end, 16 neglect patients (experimental group) were submitted to a PA treatment for 10 daily sessions. Neglect and oculo-motor responses were assessed before the treatment, 1 week, 1 and 3 months after the treatment. Eight control patients, who received general cognitive stimulation, were submitted to the same tests at the same time interval. The results showed that experimental patients obtained, as a consequence of PA, a long lasting neglect recovery, a reorganization of low-order visuo-motor behaviour during and after prism exposure (error reduction and after-effect, respectively) and a leftward deviation of oculo-motor responses. Importantly, the level of error reduction obtained in the first week of treatment was predictive of neglect recovery and the amelioration of oculo-motor responses, and the degree of eye movement deviation was positively related to neglect amelioration. Finally, the study of patients' neuroanatomical data showed that severe occipital lesions were associated with a lack of error reduction, poor neglect recovery and reduced oculo-motor system amelioration. In conclusion, the present results suggest that low-order visuo-motor reorganization induced by PA promotes a resetting of the oculo-motor system leading to an improvement in high-order visuo-spatial representation able to ameliorate neglect. PMID:16330055

  4. Association of Ego Defense Mechanisms with Academic Performance, Anxiety and Depression in Medical Students: A Mixed Methods Study

    PubMed Central

    Waqas, Ahmed; Malik, Aamenah; Muhammad, Umer; Khan, Sarah; Mahmood, Nadia

    2015-01-01

    Background: Ego defense mechanisms are unconscious psychological processes that help an individual to prevent anxiety when exposed to a stressful situation. These mechanisms are important in psychiatric practice to assess an individual’s personality dynamics, psychopathologies, and modes of coping with stressful situations, and hence, to design appropriate individualized treatment. Our study delineates the relationship of ego defense mechanisms with anxiety, depression, and academic performance of Pakistani medical students. Methods: This cross-sectional study was done at CMH Lahore Medical College and Fatima Memorial Hospital Medical and Dental College, both in Lahore, Pakistan, from December 1, 2014 to January 15, 2015. Convenience sampling was used and only students who agreed to take part in this study were included. The questionnaire consisted of three sections: 1) Demographics, documenting demographic data and academic scores on participants’ most recent exams; 2) Hospital Anxiety and Depression Scale (HADS); and 3) Defense Style Questionnaire-40 (DSQ-40). The data were analyzed with SPSS v. 20. Mean scores and frequencies were calculated for demographic variables and ego defense mechanisms. Bivariate correlations, one-way ANOVA, and multiple linear regression were used to identify associations between academic scores, demographics, ego defense mechanisms, anxiety, and depression. Results: A total of 409 medical students participated, of whom 286 (70%) were females and 123 (30%) were males. Mean percentage score on the most recent exams was 75.6% in medical students. Bivariate correlation revealed a direct association between mature and neurotic ego defense mechanisms and academic performance, and an indirect association between immature mechanisms and academic performance. One-way ANOVA showed that moderate levels of anxiety (P < .05) and low levels of depression (P < .05) were associated with higher academic performance. Conclusion: There was a

  5. A synaptic mechanism for retinal adaptation to luminance and contrast.

    PubMed

    Jarsky, Tim; Cembrowski, Mark; Logan, Stephen M; Kath, William L; Riecke, Hermann; Demb, Jonathan B; Singer, Joshua H

    2011-07-27

    The gain of signaling in primary sensory circuits is matched to the stimulus intensity by the process of adaptation. Retinal neural circuits adapt to visual scene statistics, including the mean (background adaptation) and the temporal variance (contrast adaptation) of the light stimulus. The intrinsic properties of retinal bipolar cells and synapses contribute to background and contrast adaptation, but it is unclear whether both forms of adaptation depend on the same cellular mechanisms. Studies of bipolar cell synapses identified synaptic mechanisms of gain control, but the relevance of these mechanisms to visual processing is uncertain because of the historical focus on fast, phasic transmission rather than the tonic transmission evoked by ambient light. Here, we studied use-dependent regulation of bipolar cell synaptic transmission evoked by small, ongoing modulations of membrane potential (V(M)) in the physiological range. We made paired whole-cell recordings from rod bipolar (RB) and AII amacrine cells in a mouse retinal slice preparation. Quasi-white noise voltage commands modulated RB V(M) and evoked EPSCs in the AII. We mimicked changes in background luminance or contrast, respectively, by depolarizing the V(M) or increasing its variance. A linear systems analysis of synaptic transmission showed that increasing either the mean or the variance of the presynaptic V(M) reduced gain. Further electrophysiological and computational analyses demonstrated that adaptation to mean potential resulted from both Ca channel inactivation and vesicle depletion, whereas adaptation to variance resulted from vesicle depletion alone. Thus, background and contrast adaptation apparently depend in part on a common synaptic mechanism.

  6. Stimuli-Responsive Mechanically Adaptive Polymer Nanocomposites

    PubMed Central

    Shanmuganathan, Kadhiravan; Capadona, Jeffrey R.; Rowan, Stuart J.; Weder, Christoph

    2010-01-01

    A new series of biomimetic stimuli-responsive nanocomposites, which change their mechanical properties upon exposure to physiological conditions, was prepared and investigated. The materials were produced by introducing percolating networks of cellulose nanofibers or “whiskers” derived from tunicates into poly(vinyl acetate) (PVAc), poly(butyl methacrylate) (PBMA), and blends of these polymers, with the objective of determining how the hydrophobicity and glass-transition temperature (Tg) of the polymer matrix affect the water-induced mechanically dynamic behavior. Below the Tg (~60–70 °C), the incorporation of whiskers (15.1 – 16.5% v/v) modestly increased the tensile storage moduli (E′) of the neat polymers from 0.6 to 3.8 GPa (PBMA) and from 2 to 5.2 GPa (PVAc). The reinforcement was much more dramatic above Tg, where E′ increased from 1.2 to 690 MPa (PVAc) and ~1 to 1.1 GPa (PBMA). Upon exposure to physiological conditions (immersion in artificial cerebrospinal fluid, ACSF, at 37 °C) all materials displayed a decrease of E′. The most significant contrast was seen in PVAc; for example the E′ of a 16.5% v/v PVAc/whisker nanocomposite decreased from 5.2 GPa to 12.7 MPa. Only a modest modulus decrease was measured for PBMA/whisker nanocomposite; here the E′ of a 15.1% v/v PBMA/whisker nanocomposite decreased from 3.8 to 1.2 GPa. A systematic investigation revealed that the magnitude of the mechanical contrast was related to the degree of swelling with ACSF, which was shown to increase with whisker content, temperature, and polarity of the matrix (PVAc > PBMA). The mechanical morphing of the new materials can be described in the framework of both the percolation and Halpin-Kardos models for nanocomposite reinforcement, and is the result of changing interactions among the nanoparticles and plasticization of the matrix upon swelling. PMID:20305827

  7. Biomembrane interactions reveal the mechanism of action of surface-immobilized host defense IDR-1010 peptide.

    PubMed

    Gao, Guangzheng; Cheng, John T J; Kindrachuk, Jason; Hancock, Robert E W; Straus, Suzana K; Kizhakkedathu, Jayachandran N

    2012-02-24

    Dissecting the mechanism of action of surface-tethered antimicrobial and immunomodulatory peptides is critical to the design of optimized anti-infection coatings on biomedical devices. To address this, we compared the biomembrane interactions of host defense peptide IDR-1010cys (1) in free form, (2) as a soluble polymer conjugate, and (3) with one end tethered to a solid support with model bacterial and mammalian lipid membranes. Our results show that IDR-1010cys in all three distinct forms interacted with bacterial and mammalian lipid vesicles, but the extent of the interactions as monitored by the induction of secondary structure varied. The enhanced interaction of surface-tethered peptides is well correlated with their very good antimicrobial activities. Our results demonstrate that there may be a difference in the mechanism of action of surface-tethered versus free IDR-1010cys.

  8. Systemic Acquired Resistance in Moss: Further Evidence for Conserved Defense Mechanisms in Plants

    PubMed Central

    Winter, Peter S.; Bowman, Collin E.; Villani, Philip J.; Dolan, Thomas E.; Hauck, Nathanael R.

    2014-01-01

    Vascular plants possess multiple mechanisms for defending themselves against pathogens. One well-characterized defense mechanism is systemic acquired resistance (SAR). In SAR, a plant detects the presence of a pathogen and transmits a signal throughout the plant, inducing changes in the expression of various pathogenesis-related (PR) genes. Once SAR is established, the plant is capable of mounting rapid responses to subsequent pathogen attacks. SAR has been characterized in numerous angiosperm and gymnosperm species; however, despite several pieces of evidence suggesting SAR may also exist in non-vascular plants6–8, its presence in non-vascular plants has not been conclusively demonstrated, in part due to the lack of an appropriate culture system. Here, we describe and use a novel culture system to demonstrate that the moss species Amblystegium serpens does initiate a SAR-like reaction upon inoculation with Pythium irregulare, a common soil-borne oomycete. Infection of A. serpens gametophores by P. irregulare is characterized by localized cytoplasmic shrinkage within 34 h and chlorosis and necrosis within 7 d of inoculation. Within 24 h of a primary inoculation (induction), moss gametophores grown in culture became highly resistant to infection following subsequent inoculation (challenge) by the same pathogen. This increased resistance was a response to the pathogen itself and not to physical wounding. Treatment with β-1,3 glucan, a structural component of oomycete cell walls, was equally effective at triggering SAR. Our results demonstrate, for the first time, that this important defense mechanism exists in a non-vascular plant, and, together with previous studies, suggest that SAR arose prior to the divergence of vascular and non-vascular plants. In addition, this novel moss – pathogen culture system will be valuable for future characterization of the mechanism of SAR in moss, which is necessary for a better understanding of the evolutionary history of SAR

  9. The nature of antioxidant defense mechanisms: a lesson from transgenic studies.

    PubMed Central

    Ho, Y S; Magnenat, J L; Gargano, M; Cao, J

    1998-01-01

    Reactive oxygen species (ROS) have been implicated in the pathogenesis of many clinical disorders such as adult respiratory distress syndrome, ischemia-reperfusion injury, atherosclerosis, neurodegenerative diseases, and cancer. Genetically engineered animal models have been used as a tool for understanding the function of various antioxidant enzymes in cellular defense mechanisms against various types of oxidant tissue injury. Transgenic mice overexpressing three isoforms of superoxide dismutase, catalase, and the cellular glutathione peroxidase (GSHPx-1) in various tissues show an increased tolerance to ischemia-reperfusion heart and brain injury, hyperoxia, cold-induced brain edema, adriamycin, and paraquat toxicity. These results have provided for the first time direct evidence demonstrating the importance of each of these antioxidant enzymes in protecting the animals against the injury resulting from these insults, as well as the effect of an enhanced level of antioxidant in ameliorating the oxidant tissue injury. To evaluate further the nature of these enzymes in antioxidant defense, gene knockout mice deficient in copper-zinc superoxide dismutase (CuZnSOD) and GSHPx-1 have also been generated in our laboratory. These mice developed normally and showed no marked pathologic changes under normal physiologic conditions. In addition, a deficiency in these genes had no effects on animal survival under hyperoxida. However, these knockout mice exhibited a pronounced susceptibility to paraquat toxicity and myocardial ischemia-reperfusion injury. Furthermore, female mice lacking CuZnSOD also displayed a marked increase in postimplantation embryonic lethality. These animals should provide a useful model for uncovering the identity of ROS that participate in the pathogenesis of various clinical disorders and for defining the role of each antioxidant enzyme in cellular defense against oxidant-mediated tissue injury. Images Figure 1 Figure 3 Figure 4 PMID:9788901

  10. Interrelations between hydraulic and mechanical stress adaptations in woody plants.

    PubMed

    Christensen-Dalsgaard, Karen K; Ennos, A Roland; Fournier, Meriem

    2008-07-01

    The fields of plant water relations and plant biomechanics have traditionally been studied separately even though often the same tissues are responsible for water transport and mechanical support. There is now increasing evidence that hydraulic and mechanical adaptations may influence one another. We studied the changes in the hydraulic and mechanical properties of the wood along lateral roots of two species of buttressed trees. In these roots, the mechanical contstraints quantified by strain measurements are known to decrease distally. Further, we investigated the effect of mechanical loading on the vessel anatomy in these and four other species of tropical trees. We found that as the strain decreased, the wood became progressively less stiff and strong but the conductivity increased exponentially. This was reflected in that adaptations towards re-enforcing mechanically loaded areas resulted in xylem with fewer and smaller vessels. In addition a controlled growth experiment on three tree species showed that drought adaptation may results in plants with stronger and stiffer tissue. Our results indicate that hydraulic and mechanical stress adaptations may be interrelated, and so support recent studied suggesting that physiological responses are complex balances rather than pure optimisations.

  11. Obligate Biotroph Pathogens of the Genus Albugo Are Better Adapted to Active Host Defense Compared to Niche Competitors.

    PubMed

    Ruhe, Jonas; Agler, Matthew T; Placzek, Aleksandra; Kramer, Katharina; Finkemeier, Iris; Kemen, Eric M

    2016-01-01

    Recent research suggested that plants behave differently under combined versus single abiotic and biotic stress conditions in controlled environments. While this work has provided a glimpse into how plants might behave under complex natural conditions, it also highlights the need for field experiments using established model systems. In nature, diverse microbes colonize the phyllosphere of Arabidopsis thaliana, including the obligate biotroph oomycete genus Albugo, causal agent of the common disease white rust. Biotrophic, as well as hemibiotrophic plant pathogens are characterized by efficient suppression of host defense responses. Lab experiments have even shown that Albugo sp. can suppress non-host resistance, thereby enabling otherwise avirulent pathogen growth. We asked how a pathogen that is vitally dependent on a living host can compete in nature for limited niche space while paradoxically enabling colonization of its host plant for competitors? To address this question, we used a proteomics approach to identify differences and similarities between lab and field samples of Albugo sp.-infected and -uninfected A. thaliana plants. We could identify highly similar apoplastic proteomic profiles in both infected and uninfected plants. In wild plants, however, a broad range of defense-related proteins were detected in the apoplast regardless of infection status, while no or low levels of defense-related proteins were detected in lab samples. These results indicate that Albugo sp. do not strongly affect immune responses and leave distinct branches of the immune signaling network intact. To validate our findings and to get mechanistic insights, we tested a panel of A. thaliana mutant plants with induced or compromised immunity for susceptibility to different biotrophic pathogens. Our findings suggest that the biotroph pathogen Albugo selectively interferes with host defense under different environmental and competitive pressures to maintain its ecological niche

  12. Obligate Biotroph Pathogens of the Genus Albugo Are Better Adapted to Active Host Defense Compared to Niche Competitors.

    PubMed

    Ruhe, Jonas; Agler, Matthew T; Placzek, Aleksandra; Kramer, Katharina; Finkemeier, Iris; Kemen, Eric M

    2016-01-01

    Recent research suggested that plants behave differently under combined versus single abiotic and biotic stress conditions in controlled environments. While this work has provided a glimpse into how plants might behave under complex natural conditions, it also highlights the need for field experiments using established model systems. In nature, diverse microbes colonize the phyllosphere of Arabidopsis thaliana, including the obligate biotroph oomycete genus Albugo, causal agent of the common disease white rust. Biotrophic, as well as hemibiotrophic plant pathogens are characterized by efficient suppression of host defense responses. Lab experiments have even shown that Albugo sp. can suppress non-host resistance, thereby enabling otherwise avirulent pathogen growth. We asked how a pathogen that is vitally dependent on a living host can compete in nature for limited niche space while paradoxically enabling colonization of its host plant for competitors? To address this question, we used a proteomics approach to identify differences and similarities between lab and field samples of Albugo sp.-infected and -uninfected A. thaliana plants. We could identify highly similar apoplastic proteomic profiles in both infected and uninfected plants. In wild plants, however, a broad range of defense-related proteins were detected in the apoplast regardless of infection status, while no or low levels of defense-related proteins were detected in lab samples. These results indicate that Albugo sp. do not strongly affect immune responses and leave distinct branches of the immune signaling network intact. To validate our findings and to get mechanistic insights, we tested a panel of A. thaliana mutant plants with induced or compromised immunity for susceptibility to different biotrophic pathogens. Our findings suggest that the biotroph pathogen Albugo selectively interferes with host defense under different environmental and competitive pressures to maintain its ecological niche

  13. Obligate Biotroph Pathogens of the Genus Albugo Are Better Adapted to Active Host Defense Compared to Niche Competitors

    PubMed Central

    Ruhe, Jonas; Agler, Matthew T.; Placzek, Aleksandra; Kramer, Katharina; Finkemeier, Iris; Kemen, Eric M.

    2016-01-01

    Recent research suggested that plants behave differently under combined versus single abiotic and biotic stress conditions in controlled environments. While this work has provided a glimpse into how plants might behave under complex natural conditions, it also highlights the need for field experiments using established model systems. In nature, diverse microbes colonize the phyllosphere of Arabidopsis thaliana, including the obligate biotroph oomycete genus Albugo, causal agent of the common disease white rust. Biotrophic, as well as hemibiotrophic plant pathogens are characterized by efficient suppression of host defense responses. Lab experiments have even shown that Albugo sp. can suppress non-host resistance, thereby enabling otherwise avirulent pathogen growth. We asked how a pathogen that is vitally dependent on a living host can compete in nature for limited niche space while paradoxically enabling colonization of its host plant for competitors? To address this question, we used a proteomics approach to identify differences and similarities between lab and field samples of Albugo sp.-infected and -uninfected A. thaliana plants. We could identify highly similar apoplastic proteomic profiles in both infected and uninfected plants. In wild plants, however, a broad range of defense-related proteins were detected in the apoplast regardless of infection status, while no or low levels of defense-related proteins were detected in lab samples. These results indicate that Albugo sp. do not strongly affect immune responses and leave distinct branches of the immune signaling network intact. To validate our findings and to get mechanistic insights, we tested a panel of A. thaliana mutant plants with induced or compromised immunity for susceptibility to different biotrophic pathogens. Our findings suggest that the biotroph pathogen Albugo selectively interferes with host defense under different environmental and competitive pressures to maintain its ecological niche

  14. Monuments of memory: defensive mechanisms of the collective psyche and their manifestation in the memorialization process.

    PubMed

    Kalinowska, Malgorzata

    2012-09-01

    The paper searches for insight in the area of collective memory as a part of collective consciousness, a phenomenon understood as a stabilizing factor for a society's self-image and identity. Collective memories are seen as originating from shared communications transmitting and creating the meaning of the past in the form of narrative, symbols and signs. As such, they contain the individual, embodied and lived side of our relations to the past. As well as the identity-building and meaning-making functions of collective memories, their defensive function is discussed with a focus on commemorative practices taking place in a transitional space between psychic and social life. Fears of a lack of collective identity and coherence have contributed to the way Polish commemorative practices have been shaped. This is considered in relation to the Smolensk catastrophe in 2010, viewed in the context of the Jungian concept of the collective psyche and the psychoanalytical understanding of defensive group mechanisms against trauma, especially those relating to loss and mourning. It leads to a consideration of how historical experiences and the experience of history can be accessed, as well as their meaning for individual and group development. PMID:22954041

  15. Preventive role of lens antioxidant defense mechanism against riboflavin-mediated sunlight damaging of lens crystallins.

    PubMed

    Anbaraki, Afrooz; Khoshaman, Kazem; Ghasemi, Younes; Yousefi, Reza

    2016-10-01

    The main components of sunlight reaching the eye lens are UVA and visible light exerting their photo-damaging effects indirectly by the aid of endogenous photosensitizer molecules such as riboflavin (RF). In this study, lens proteins solutions were incubated with RF and exposed to the sunlight. Then, gel mobility shift analysis and different spectroscopic assessments were applied to examine the structural damaging effects of solar radiation on these proteins. Exposure of lens proteins to direct sunlight, in the presence of RF, leads to marked structural crosslinking, oligomerization and proteolytic instability. These structural damages were also accompanied with reduction in the emission fluorescence of Trp and Tyr and appearance of a new absorption peak between 300 and 400nm which can be related to formation of new chromophores. Also, photo-oxidation of lens crystallins increases their oligomeric size distribution as examined by dynamic light scattering analysis. The above mentioned structural insults, as potential sources of sunlight-induced senile cataract and blindness, were significantly attenuated in the presence of ascorbic acid and glutathione which are two important components of lens antioxidant defense system. Therefore, the powerful antioxidant defense mechanism of eye lens is an important barrier against molecular photo-damaging effects of solar radiations during the life span. PMID:27316765

  16. Luminal l-glutamate enhances duodenal mucosal defense mechanisms via multiple glutamate receptors in rats

    PubMed Central

    Watanabe, Chikako; Mizumori, Misa; Kaunitz, Jonathan D.

    2009-01-01

    Presence of taste receptor families in the gastrointestinal mucosa suggests a physiological basis for local and early detection of a meal. We hypothesized that luminal l-glutamate, which is the primary nutrient conferring fundamental umami or proteinaceous taste, influences mucosal defense mechanisms in rat duodenum. We perfused the duodenal mucosa of anesthetized rats with l-glutamate (0.1–10 mM). Intracellular pH (pHi) of the epithelial cells, blood flow, and mucus gel thickness (MGT) were simultaneously and continuously measured in vivo. Some rats were pretreated with indomethacin or capsaicin. Duodenal bicarbonate secretion (DBS) was measured with flow-through pH and CO2 electrodes. We tested the effects of agonists or antagonists for metabotropic glutamate receptor (mGluR) 1 or 4 or calcium-sensing receptor (CaSR) on defense factors. Luminal l-glutamate dose dependently increased pHi and MGT but had no effect on blood flow in the duodenum. l-glutamate (10 mM)-induced cellular alkalinization and mucus secretion were inhibited by pretreatment with indomethacin or capsaicin. l-glutamate effects on pHi and MGT were mimicked by mGluR4 agonists and inhibited by an mGluR4 antagonist. CaSR agonists acidified cells with increased MGT and DBS, unlike l-glutamate. Perfusion of l-glutamate with inosinate (inosine 5′-monophosphate, 0.1 mM) enhanced DBS only in combination, suggesting synergistic activation of the l-glutamate receptor, typical of taste receptor type 1. l-leucine or l-aspartate had similar effects on DBS without any effect on pHi and MGT. Preperfusion of l-glutamate prevented acid-induced cellular injury, suggesting that l-glutamate protects the mucosa by enhancing mucosal defenses. Luminal l-glutamate may activate multiple receptors and afferent nerves and locally enhance mucosal defenses to prevent subsequent injury attributable to acid exposure in the duodenum. PMID:19643955

  17. Mechanical Properties of Sialic Foamed Ceramic and Applications in Defense Structure

    NASA Astrophysics Data System (ADS)

    Li, Xu-Yang; Li, Yong-Chi; Zhao, Kai; Gao, Guang-Fa

    2014-08-01

    Mechanical properties of a closed-cellular sialic foamed ceramic are investigated by compressive tests. The sialic foamed ceramic under uniaxial stress compression shows brittleness and the flow stress increases with the strain rate. The engineering stress-engineering strain curve under uniaxial strain compression could be divided into three stages: linear elasticity, collapsed plateau and densification. The unloading elastic modulus, Poisson ratio and energy absorption ability are discussed. Shelly cellular material made by sialic foamed ceramic is applied into the stress distribution layer in the defense structure. Field explosion experiments are performed for the sand based stress distribution layer and shelly cellular material based layer. Compared with sand, the shelly cellular material reduces the peak stress of the blast wave.

  18. Roles of small RNAs in the immune defense mechanisms of crustaceans.

    PubMed

    He, Yaodong; Ju, Chenyu; Zhang, Xiaobo

    2015-12-01

    Small RNAs, 21-24 nucleotides in length, are non-coding RNAs found in most multicellular organisms, as well as in some viruses. There are three main types of small RNAs including microRNA (miRNA), small-interfering RNA (siRNA), and piwi-interacting RNA (piRNA). Small RNAs play key roles in the genetic regulation of eukaryotes; at least 50% of all eukaryote genes are the targets of small RNAs. In recent years, studies have shown that some unique small RNAs are involved in the immune response of crustaceans, leading to lower or higher immune responses to infections and diseases. SiRNAs could be used as therapy for virus infection. In this review, we provide an overview of the diverse roles of small RNAs in the immune defense mechanisms of crustaceans. PMID:26210184

  19. [The defense and regulatory mechanisms during development of legume-Rhizobium symbiosis].

    PubMed

    Glian'ko, A K; Akimova, G P; Sokolova, M G; Makarova, L E; Vasil'eva, G G

    2007-01-01

    The roles of indolylacetic acid, the peroxidase system, catalase, active oxygen species, and phenolic compounds in the physiological and biochemical mechanisms involved in the autoregulation of nodulation in the developing legume-Rhizobium symbiosis were studied. It was inferred that the concentration of indolylacetic acid in the roots of inoculated plants, controlled by the enzymes of the peroxidase complex, is the signal permitting or limiting nodulation at the initial stages of symbiotic interaction. Presumably, the change in the level of active oxygen species is determined by an antioxidant activity of phenolic compounds. During the development of symbiosis, phytohormones, antioxidant enzymes, and active oxygen species may be involved in the regulation of infection via both a direct antibacterial action and regulation of functional activity of the host plant defense systems. PMID:17619575

  20. Stress defense mechanisms of NADPH-dependent thioredoxin reductases (NTRs) in plants.

    PubMed

    Cha, Joon-Yung; Barman, Dhirendra Nath; Kim, Min Gab; Kim, Woe-Yeon

    2015-01-01

    Plants establish highly and systemically organized stress defense mechanisms against unfavorable living conditions. To interpret these environmental stimuli, plants possess communication tools, referred as secondary messengers, such as Ca(2+) signature and reactive oxygen species (ROS) wave. Maintenance of ROS is an important event for whole lifespan of plants, however, in special cases, toxic ROS molecules are largely accumulated under excess stresses and diverse enzymes played as ROS scavengers. Arabidopsis and rice contain 3 NADPH-dependent thioredoxin reductases (NTRs) which transfer reducing power to Thioredoxin/Peroxiredoxin (Trx/Prx) system for scavenging ROS. However, due to functional redundancy between cytosolic and mitochondrial NTRs (NTRA and NTRB, respectively), their functional involvements under stress conditions have not been well characterized. Recently, we reported that cytosolic NTRA confers the stress tolerance against oxidative and drought stresses via regulation of ROS amounts using NTRA-overexpressing plants. With these findings, mitochondrial NTRB needs to be further elucidated.

  1. Attenuation of cellular antioxidant defense mechanisms in kidney of rats intoxicated with carbofuran.

    PubMed

    Kaur, Bhupindervir; Khera, Alka; Sandhir, Rajat

    2012-10-01

    Carbofuran, an anticholinestrase carbamate, is commonly used as an insecticide. Its toxic effect on kidney is less established. The present study was designed to investigate the effect of carbofuran on kidneys and to understand the mechanism involved in its nephrotoxicity. Male Wistar rats were divided into two groups of eight animals each; control animals received sunflower oil (vehicle) and carbofuran exposed animals were treated with carbofuran (1 mg/kg body weight) orally for 28 days. At the end of the treatment, significant increase was observed in urea and creatinine levels in serum along with the inhibition of acetylcholinesterase, suggesting nephrotoxicity. The antioxidant defense system of animals treated with carbofuran was altered in terms of increased lipid peroxidation, reduced glutathione, and total thiols and decreased activity of antioxidant enzymes (superoxide dismutase and catalase). The results indicate that carbofuran is nephrotoxic and increased oxidative stress appears to be involved in its nephrotoxic effects.

  2. Mitochondrial respiratory-chain adaptations in macrophages contribute to antibacterial host defense.

    PubMed

    Garaude, Johan; Acín-Pérez, Rebeca; Martínez-Cano, Sarai; Enamorado, Michel; Ugolini, Matteo; Nistal-Villán, Estanislao; Hervás-Stubbs, Sandra; Pelegrín, Pablo; Sander, Leif E; Enríquez, José A; Sancho, David

    2016-09-01

    Macrophages tightly scale their core metabolism after being activated, but the precise regulation of the mitochondrial electron-transport chain (ETC) and its functional implications are currently unknown. Here we found that recognition of live bacteria by macrophages transiently decreased assembly of the ETC complex I (CI) and CI-containing super-complexes and switched the relative contributions of CI and CII to mitochondrial respiration. This was mediated by phagosomal NADPH oxidase and the reactive oxygen species (ROS)-dependent tyrosine kinase Fgr. It required Toll-like receptor signaling and the NLRP3 inflammasome, which were both connected to bacterial viability-specific immune responses. Inhibition of CII during infection with Escherichia coli normalized serum concentrations of interleukin 1β (IL-1β) and IL-10 to those in mice treated with dead bacteria and impaired control of bacteria. We have thus identified ETC adaptations as an early immunological-metabolic checkpoint that adjusts innate immune responses to bacterial infection.

  3. The evolution of defense mechanisms correlate with the explosive diversification of autodigesting Coprinellus mushrooms (Agaricales, Fungi).

    PubMed

    Nagy, László G; Házi, Judit; Szappanos, Balázs; Kocsubé, Sándor; Bálint, Balázs; Rákhely, Gábor; Vágvölgyi, Csaba; Papp, Tamás

    2012-07-01

    Bursts of diversification are known to have contributed significantly to the extant morphological and species diversity, but evidence for many of the theoretical predictions about adaptive radiations have remained contentious. Despite their tremendous diversity, patterns of evolutionary diversification and the contribution of explosive episodes in fungi are largely unknown. Here, using the genus Coprinellus (Psathyrellaceae, Agaricales) as a model, we report the first explosive fungal radiation and infer that the onset of the radiation correlates with a change from a multilayered to a much simpler defense structure on the fruiting bodies. We hypothesize that this change constitutes a key innovation, probably relaxing constraints on diversification imposed by nutritional investment into the development of protective tissues of fruiting bodies. Fossil calibration suggests that Coprinellus mushrooms radiated during the Miocene coinciding with global radiation of large grazing mammals following expansion of dry open grasslands. In addition to diversification rate-based methods, we test the hard polytomy hypothesis, by analyzing the resolvability of internal nodes of the backbone of the putative radiation using Reversible-Jump MCMC. We discuss potential applications and pitfalls of this approach as well as how biologically meaningful polytomies can be distinguished from alignment shortcomings. Our data provide insights into the nature of adaptive radiations in general by revealing a deceleration of morphological diversification through time. The dynamics of morphological diversification was approximated by obtaining the temporal distribution of state changes in discrete traits along the trees and comparing it with the tempo of lineage accumulation. We found that the number of state changes correlate with the number of lineages, even in parts of the tree with short internal branches, and peaks around the onset of the explosive radiation followed by a slowdown, most

  4. The role of mammalian antimicrobial peptides and proteins in awakening of innate host defenses and adaptive immunity.

    PubMed

    Yang, D; Chertov, O; Oppenheim, J J

    2001-06-01

    Since we live in a dirty environment, we have developed many host defenses to contend with microorganisms. The epithelial lining of our skin, gastrointestinal tract and bronchial tree produces a number of antibacterial peptides, and our phagocytic neutrophils rapidly ingest and enzymatically degrade invading organisms, as well as produce peptides and enzymes with antimicrobial activities. Some of these antimicrobial moieties also appear to alert host cells involved in both innate host defense and adaptive immune responses. The epithelial cells are a source of constitutively produced beta defensin (HBD1) and proinflammatory cytokine-inducible beta defensins (HBD2 and -3) and cathelicidin (LL37). The neutrophils-derived antimicrobial peptides are released on demand from their cytoplasmic granules. They include the enzymes cathepsin G and chymase, azurocidin, a defensins and cathelicidin. In contrast, C5a and C3b are produced by activation of the serum complement cascade. The antimicrobial moieties direct the migration and activate target cells by interacting with selected G-protein-coupled seven-transmembrane receptors (GPCRs) on cell surfaces. The beta defensins interact with the CCR6 chemokine GPCRs, whereas cathelicidins interact with the low-affinity FPRL-1 receptors. The neutrophil-derived cathepsin G acts on the high-affinity FMLP receptor (GPCR) known as FPR, while the receptors for chymase and azurocidin have not been identified as yet. The serum-derived C5a uses a GPCR known as C5aR to mediate its chemotactic and cell-activating effects. Consequently, all these ligand-receptor interactions in addition to mediating chemotaxis also activate receptor-expressing cells to produce other mediators of inflammation.

  5. CRISPR-Cas adaptation: insights into the mechanism of action.

    PubMed

    Amitai, Gil; Sorek, Rotem

    2016-02-01

    Since the first demonstration that CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against phages and plasmids, numerous studies have yielded key insights into the molecular mechanisms governing how these systems attack and degrade foreign DNA. However, the molecular mechanisms underlying the adaptation stage, in which new immunological memory is formed, have until recently represented a major unresolved question. In this Progress article, we discuss recent discoveries that have shown both how foreign DNA is identified by the CRISPR-Cas adaptation machinery and the molecular basis for its integration into the chromosome to form an immunological memory. Furthermore, we describe the roles of each of the specific CRISPR-Cas components that are involved in memory formation, and consider current models for their evolutionary origin.

  6. Strong down-regulation of glycophorin genes: A host defense mechanism against rotavirus infection.

    PubMed

    Salas, Antonio; Marco-Puche, Guillermo; Triviño, Juan Carlos; Gómez-Carballa, Alberto; Cebey-López, Miriam; Rivero-Calle, Irene; Vilanova-Trillo, Lucía; Rodríguez-Tenreiro, Carmen; Gómez-Rial, José; Martinón-Torres, Federico

    2016-10-01

    The mechanisms of rotavirus (RV) infection have been analyzed from different angles but the way in which RV modifies the transcriptome of the host is still unknown. Whole transcriptome shotgun sequencing of peripheral blood samples was used to reveal patterns of expression from the genome of RV-infected patients. RV provokes global changes in the transcriptome of infected cells, involving an over-expression of genes involved in cell cycle and chromatin condensation. While interferon IFI27 was hyper-activated, interferon type II was not suggesting that RV has developed mechanisms to evade the innate response by host cells after virus infection. Most interesting was the inhibition of genes of the glycophorins A and B (GYPA/B) family, which are the major sialoglycoproteins of the human erythrocyte membrane and receptor of several viruses for host invasion. RV infection induces a complex and global response in the host. The strong inhibition of glycophorins suggests a novel defense mechanism of the host to prevent viral infection, inhibiting the expression of receptors used by the virus for infection. The present results add further support to the systemic nature of RV infection.

  7. In Vivo NMR Metabolic Profiling of Fabrea salina Reveals Sequential Defense Mechanisms against Ultraviolet Radiation

    PubMed Central

    Marangoni, Roberto; Paris, Debora; Melck, Dominique; Fulgentini, Lorenzo; Colombetti, Giuliano; Motta, Andrea

    2011-01-01

    Fabrea salina is a hypersaline ciliate that is known to be among the strongest ultraviolet (UV)-resistant microorganisms; however, the molecular mechanisms of this resistance are almost unknown. By means of in vivo NMR spectroscopy, we determined the metabolic profile of living F. salina cells exposed to visible light and to polychromatic UV-B + UV-A + Vis radiation for several different exposure times. We used unsupervised pattern-recognition analysis to compare these profiles and discovered some metabolites whose concentration changed specifically upon UV exposure and in a dose-dependent manner. This variation was interpreted in terms of a two-phase cell reaction involving at least two different pathways: an early response consisting of degradation processes, followed by a late response activating osmoprotection mechanisms. The first step alters the concentration of formate, acetate, and saturated fatty-acid metabolites, whereas the osmoprotection modifies the activity of betaine moieties and other functionally related metabolites. In the latter pathway, alanine, proline, and sugars suggest a possible incipient protein synthesis as defense and/or degeneration mechanisms. We conclude that NMR spectroscopy on in vivo cells is an optimal approach for investigating the effect of UV-induced stress on the whole metabolome of F. salina because it minimizes the invasiveness of the measurement. PMID:21190674

  8. Strong down-regulation of glycophorin genes: A host defense mechanism against rotavirus infection.

    PubMed

    Salas, Antonio; Marco-Puche, Guillermo; Triviño, Juan Carlos; Gómez-Carballa, Alberto; Cebey-López, Miriam; Rivero-Calle, Irene; Vilanova-Trillo, Lucía; Rodríguez-Tenreiro, Carmen; Gómez-Rial, José; Martinón-Torres, Federico

    2016-10-01

    The mechanisms of rotavirus (RV) infection have been analyzed from different angles but the way in which RV modifies the transcriptome of the host is still unknown. Whole transcriptome shotgun sequencing of peripheral blood samples was used to reveal patterns of expression from the genome of RV-infected patients. RV provokes global changes in the transcriptome of infected cells, involving an over-expression of genes involved in cell cycle and chromatin condensation. While interferon IFI27 was hyper-activated, interferon type II was not suggesting that RV has developed mechanisms to evade the innate response by host cells after virus infection. Most interesting was the inhibition of genes of the glycophorins A and B (GYPA/B) family, which are the major sialoglycoproteins of the human erythrocyte membrane and receptor of several viruses for host invasion. RV infection induces a complex and global response in the host. The strong inhibition of glycophorins suggests a novel defense mechanism of the host to prevent viral infection, inhibiting the expression of receptors used by the virus for infection. The present results add further support to the systemic nature of RV infection. PMID:27491455

  9. An adaptive neural swarm approach for intrusion defense in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Cannady, James

    2011-06-01

    Wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are being increasingly deployed in critical applications due to the flexibility and extensibility of the technology. While these networks possess numerous advantages over traditional wireless systems in dynamic environments they are still vulnerable to many of the same types of host-based and distributed attacks common to those systems. Unfortunately, the limited power and bandwidth available in WSNs and MANETs, combined with the dynamic connectivity that is a defining characteristic of the technology, makes it extremely difficult to utilize traditional intrusion detection techniques. This paper describes an approach to accurately and efficiently detect potentially damaging activity in WSNs and MANETs. It enables the network as a whole to recognize attacks, anomalies, and potential vulnerabilities in a distributive manner that reflects the autonomic processes of biological systems. Each component of the network recognizes activity in its local environment and then contributes to the overall situational awareness of the entire system. The approach utilizes agent-based swarm intelligence to adaptively identify potential data sources on each node and on adjacent nodes throughout the network. The swarm agents then self-organize into modular neural networks that utilize a reinforcement learning algorithm to identify relevant behavior patterns in the data without supervision. Once the modular neural networks have established interconnectivity both locally and with neighboring nodes the analysis of events within the network can be conducted collectively in real-time. The approach has been shown to be extremely effective in identifying distributed network attacks.

  10. When Do Adaptive Developmental Mechanisms Yield Maladaptive Outcomes?

    ERIC Educational Resources Information Center

    Frankenhuis, Willem E.; Del Giudice, Marco

    2012-01-01

    This article discusses 3 ways in which adaptive developmental mechanisms may produce maladaptive outcomes. First, natural selection may favor risky strategies that enhance fitness on average but which have detrimental consequences for a subset of individuals. Second, mismatch may result when organisms experience environmental change during…

  11. Defense mechanisms of sargassacean species against the epiphytic red alga Neosiphonia harveyi.

    PubMed

    Nakajima, Noboru; Ohki, Kaori; Kamiya, Mitsunobu

    2015-08-01

    Flora diversity and abundance of epiphytes are specific to their basiphyte species and may relate to variations in the defensive abilities of basiphytes. Thus, investigating the interactions between epiphytes and basiphytes is useful for a better understanding of the biological impact of epiphytism and the survival strategies of basiphytes. We examined the epiphyte density on five sargassacean species at six locations between two study sites, which showed that the epiphytic red alga Neosiphonia harveyi was remarkably less abundant on Sargassum siliquastrum at all locations. To assess its defense mechanism against N. harveyi, we performed bioassays of phlorotannins, which are considered effective in deterring fouling, by culturing sargassacean blades with N. harveyi carpospores and observed the process by which sargassacean blades remove epiphytes. When the carpospores were incubated with various concentrations of dissolved phlorotannins, settlement and germination were inhibited only at the highest concentrations (>0.1 g · L(-1) ), and this effect did not significantly differ among the five sargassacean species. When the carpospores were combined with blades from the five species, many of the spores attached and germinated on every blade. Because N. harveyi penetrated rhizoids into basiphyte tissues, cuticle peeling observed in all five sargassacean species could not remove this epiphyte after germination. However, in S. siliquastrum, the blade tissues around the germlings became swollen and disintegrative, and were removed together with the germlings. The spores normally grew on the dead blades, suggesting that the tissue degradation of S. siliquastrum is triggered by the infection of N. harveyi. PMID:26986791

  12. NO-dependent mechanisms of adaptation to hypoxia.

    PubMed

    Malyshev, I Y; Zenina, T A; Golubeva, L Y; Saltykova, V A; Manukhina, E B; Mikoyan, V D; Kubrina, L N; Vanin, A F

    1999-01-01

    In studying NO-dependent mechanisms of resistance to hypoxia, it was shown that (1) acute hypoxia induces NO overproduction in brain and leaves unaffected NO production in liver of rats; (2) adaptation to hypoxia decreases NO production in liver and brain; and (3) adaptation to hypoxia prevents NO overproduction in brain and potentiates NO synthesis in liver in acute hypoxia. Dinitrosyl iron complex (DNIC, 200 microg/kg, single dose, iv), a NO donor, decreases the resistance of animals to acute hypoxia by 30%. Nomega-nitro-L-arginine (L-NNA, 50 mg/kg, single dose, ip), a NO synthase inhibitor, and diethyl dithiocarbamate (DETC, 200 mg/kg, single dose, iv), a NO trap, increases this parameter 1.3 and 2 times, respectively. Adaptation to hypoxia developed against a background of accumulation of heat shock protein HSP70 in liver and brain. A course of DNIC reproduced the antihypoxic effect of adaptation. A course of L-NNA during adaptation hampered both accumulation of HSP70 and development of the antihypoxic effect. Therefore, NO and the NO-dependent activation of HSP70 synthesis play important roles in adaptation to hypoxia. PMID:10369180

  13. Plant storage proteins with antimicrobial activity: novel insights into plant defense mechanisms.

    PubMed

    Cândido, Elizabete de Souza; Pinto, Michelle Flaviane Soares; Pelegrini, Patrícia Barbosa; Lima, Thais Bergamin; Silva, Osmar Nascimento; Pogue, Robert; Grossi-de-Sá, Maria Fátima; Franco, Octávio Luiz

    2011-10-01

    Storage proteins perform essential roles in plant survival, acting as molecular reserves important for plant growth and maintenance, as well as being involved in defense mechanisms by virtue of their properties as insecticidal and antimicrobial proteins. These proteins accumulate in storage vacuoles inside plant cells, and, in response to determined signals, they may be used by the different plant tissues in response to pathogen attack. To shed some light on these remarkable proteins with dual functions, storage proteins found in germinative tissues, such as seeds and kernels, and in vegetative tissues, such as tubercles and leaves, are extensively discussed here, along with the related mechanisms of protein expression. Among these proteins, we focus on 2S albumins, Kunitz proteinase inhibitors, plant lectins, glycine-rich proteins, vicilins, patatins, tarins, and ocatins. Finally, the potential use of these molecules in development of drugs to combat human and plant pathogens, contributing to the development of new biotechnology-based medications and products for agribusiness, is also presented.

  14. Chromosome-level genome map provides insights into diverse defense mechanisms in the medicinal fungus Ganoderma sinense

    PubMed Central

    Zhu, Yingjie; Xu, Jiang; Sun, Chao; Zhou, Shiguo; Xu, Haibin; Nelson, David R.; Qian, Jun; Song, Jingyuan; Luo, Hongmei; Xiang, Li; Li, Ying; Xu, Zhichao; Ji, Aijia; Wang, Lizhi; Lu, Shanfa; Hayward, Alice; Sun, Wei; Li, Xiwen; Schwartz, David C.; Wang, Yitao; Chen, Shilin

    2015-01-01

    Fungi have evolved powerful genomic and chemical defense systems to protect themselves against genetic destabilization and other organisms. However, the precise molecular basis involved in fungal defense remain largely unknown in Basidiomycetes. Here the complete genome sequence, as well as DNA methylation patterns and small RNA transcriptomes, was analyzed to provide a holistic overview of secondary metabolism and defense processes in the model medicinal fungus, Ganoderma sinense. We reported the 48.96 Mb genome sequence of G. sinense, consisting of 12 chromosomes and encoding 15,688 genes. More than thirty gene clusters involved in the biosynthesis of secondary metabolites, as well as a large array of genes responsible for their transport and regulation were highlighted. In addition, components of genome defense mechanisms, namely repeat-induced point mutation (RIP), DNA methylation and small RNA-mediated gene silencing, were revealed in G. sinense. Systematic bioinformatic investigation of the genome and methylome suggested that RIP and DNA methylation combinatorially maintain G. sinense genome stability by inactivating invasive genetic material and transposable elements. The elucidation of the G. sinense genome and epigenome provides an unparalleled opportunity to advance our understanding of secondary metabolism and fungal defense mechanisms. PMID:26046933

  15. Chromosome-level genome map provides insights into diverse defense mechanisms in the medicinal fungus Ganoderma sinense.

    PubMed

    Zhu, Yingjie; Xu, Jiang; Sun, Chao; Zhou, Shiguo; Xu, Haibin; Nelson, David R; Qian, Jun; Song, Jingyuan; Luo, Hongmei; Xiang, Li; Li, Ying; Xu, Zhichao; Ji, Aijia; Wang, Lizhi; Lu, Shanfa; Hayward, Alice; Sun, Wei; Li, Xiwen; Schwartz, David C; Wang, Yitao; Chen, Shilin

    2015-06-05

    Fungi have evolved powerful genomic and chemical defense systems to protect themselves against genetic destabilization and other organisms. However, the precise molecular basis involved in fungal defense remain largely unknown in Basidiomycetes. Here the complete genome sequence, as well as DNA methylation patterns and small RNA transcriptomes, was analyzed to provide a holistic overview of secondary metabolism and defense processes in the model medicinal fungus, Ganoderma sinense. We reported the 48.96 Mb genome sequence of G. sinense, consisting of 12 chromosomes and encoding 15,688 genes. More than thirty gene clusters involved in the biosynthesis of secondary metabolites, as well as a large array of genes responsible for their transport and regulation were highlighted. In addition, components of genome defense mechanisms, namely repeat-induced point mutation (RIP), DNA methylation and small RNA-mediated gene silencing, were revealed in G. sinense. Systematic bioinformatic investigation of the genome and methylome suggested that RIP and DNA methylation combinatorially maintain G. sinense genome stability by inactivating invasive genetic material and transposable elements. The elucidation of the G. sinense genome and epigenome provides an unparalleled opportunity to advance our understanding of secondary metabolism and fungal defense mechanisms.

  16. Phenotypic Plasticity and Selection: Nonexclusive Mechanisms of Adaptation

    PubMed Central

    Grenier, S.; Barre, P.; Litrico, I.

    2016-01-01

    Selection and plasticity are two mechanisms that allow the adaptation of a population to a changing environment. Interaction between these nonexclusive mechanisms must be considered if we are to understand population survival. This review discusses the ways in which plasticity and selection can interact, based on a review of the literature on selection and phenotypic plasticity in the evolution of populations. The link between selection and phenotypic plasticity is analysed at the level of the individual. Plasticity can affect an individual's response to selection and so may modify the end result of genetic diversity evolution at population level. Genetic diversity increases the ability of populations or communities to adapt to new environmental conditions. Adaptive plasticity increases individual fitness. However this effect must be viewed from the perspective of the costs of plasticity, although these are not easy to estimate. It is becoming necessary to engage in new experimental research to demonstrate the combined effects of selection and plasticity for adaptation and their consequences on the evolution of genetic diversity. PMID:27313957

  17. Visual-adaptation-mechanism based underwater object extraction

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  18. Adaptive mechanism-based congestion control for networked systems

    NASA Astrophysics Data System (ADS)

    Liu, Zhi; Zhang, Yun; Chen, C. L. Philip

    2013-03-01

    In order to assure the communication quality in network systems with heavy traffic and limited bandwidth, a new ATRED (adaptive thresholds random early detection) congestion control algorithm is proposed for the congestion avoidance and resource management of network systems. Different to the traditional AQM (active queue management) algorithms, the control parameters of ATRED are not configured statically, but dynamically adjusted by the adaptive mechanism. By integrating with the adaptive strategy, ATRED alleviates the tuning difficulty of RED (random early detection) and shows a better control on the queue management, and achieve a more robust performance than RED under varying network conditions. Furthermore, a dynamic transmission control protocol-AQM control system using ATRED controller is introduced for the systematic analysis. It is proved that the stability of the network system can be guaranteed when the adaptive mechanism is finely designed. Simulation studies show the proposed ATRED algorithm achieves a good performance in varying network environments, which is superior to the RED and Gentle-RED algorithm, and providing more reliable service under varying network conditions.

  19. Mechanical signal transduction in skeletal muscle growth and adaptation.

    PubMed

    Tidball, James G

    2005-05-01

    The adaptability of skeletal muscle to changes in the mechanical environment has been well characterized at the tissue and system levels, but the mechanisms through which mechanical signals are transduced to chemical signals that influence muscle growth and metabolism remain largely unidentified. However, several findings have suggested that mechanical signal transduction in muscle may occur through signaling pathways that are shared with insulin-like growth factor (IGF)-I. The involvement of IGF-I-mediated signaling for mechanical signal transduction in muscle was originally suggested by the observations that muscle releases IGF-I on mechanical stimulation, that IGF-I is a potent agent for promoting muscle growth and affecting phenotype, and that IGF-I can function as an autocrine hormone in muscle. Accumulating evidence shows that at least two signaling pathways downstream of IGF-I binding can influence muscle growth and adaptation. Signaling via the calcineurin/nuclear factor of activated T-cell pathway has been shown to have a powerful influence on promoting the slow/type I phenotype in muscle but can also increase muscle mass. Neural stimulation of muscle can activate this pathway, although whether neural activation of the pathway can occur independent of mechanical activation or independent of IGF-I-mediated signaling remains to be explored. Signaling via the Akt/mammalian target of rapamycin pathway can also increase muscle growth, and recent findings show that activation of this pathway can occur as a response to mechanical stimulation applied directly to muscle cells, independent of signals derived from other cells. In addition, mechanical activation of mammalian target of rapamycin, Akt, and other downstream signals is apparently independent of autocrine factors, which suggests that activation of the mechanical pathway occurs independent of muscle-mediated IGF-I release.

  20. Defense Mechanisms Reported by Patients with Borderline Personality Disorder and Axis II Comparison Subjects Over 16 Years of Prospective Follow-up: Description and Prediction of Recovery

    PubMed Central

    Zanarini, Mary C.; Frankenburg, Frances R.; Fitzmaurice, Garrett

    2012-01-01

    Objective This study assessed the defensive functioning of 290 borderline patients and compared it to that of 72 patients with other forms of axis II psychopathology over 16 years of prospective follow-up. It also assessed the relationship between time-varying defenses and recovery from borderline personality disorder. Method The Defense Style Questionnaire, a self-report measure with demonstrated criterion validity and internal consistency, was initially administered at study entry. It was readministered at eight contiguous two-year long follow-up periods. Results Borderline patients had significantly lower scores than axis II comparison subjects on one mature defense mechanism (suppression) and significantly higher scores on seven of the other 18 defenses studied. More specifically, borderline patients had significantly higher scores on one neurotic-level defense (undoing), four immature defenses (acting out, emotional hypochondriasis, passive aggression, and projection), and two image-distorting/borderline defenses (projective identification and splitting). In terms of change, borderline patients were found to have had significant improvement on 13 of the 19 defenses studied. More specifically, they had significantly higher scores over time on one mature defense (anticipation) and significantly lower scores on two neurotic defenses (isolation and undoing), all immature defenses, and all image-distorting/borderline defenses except primitive idealization. In addition, four time-varying defense mechanisms were found to predict time-to-recovery: humor, acting out, emotional hypochondriasis, and projection. Conclusions Taken together, the results of this study suggest that the longitudinal defensive functioning of borderline patients is both distinct and improves substantially over time. They also suggest that immature defenses are the best predictors of time-to-recovery. PMID:23223866

  1. Genome analysis of three Pneumocystis species reveals adaptation mechanisms to life exclusively in mammalian hosts.

    PubMed

    Ma, Liang; Chen, Zehua; Huang, Da Wei; Kutty, Geetha; Ishihara, Mayumi; Wang, Honghui; Abouelleil, Amr; Bishop, Lisa; Davey, Emma; Deng, Rebecca; Deng, Xilong; Fan, Lin; Fantoni, Giovanna; Fitzgerald, Michael; Gogineni, Emile; Goldberg, Jonathan M; Handley, Grace; Hu, Xiaojun; Huber, Charles; Jiao, Xiaoli; Jones, Kristine; Levin, Joshua Z; Liu, Yueqin; Macdonald, Pendexter; Melnikov, Alexandre; Raley, Castle; Sassi, Monica; Sherman, Brad T; Song, Xiaohong; Sykes, Sean; Tran, Bao; Walsh, Laura; Xia, Yun; Yang, Jun; Young, Sarah; Zeng, Qiandong; Zheng, Xin; Stephens, Robert; Nusbaum, Chad; Birren, Bruce W; Azadi, Parastoo; Lempicki, Richard A; Cuomo, Christina A; Kovacs, Joseph A

    2016-01-01

    Pneumocystis jirovecii is a major cause of life-threatening pneumonia in immunosuppressed patients including transplant recipients and those with HIV/AIDS, yet surprisingly little is known about the biology of this fungal pathogen. Here we report near complete genome assemblies for three Pneumocystis species that infect humans, rats and mice. Pneumocystis genomes are highly compact relative to other fungi, with substantial reductions of ribosomal RNA genes, transporters, transcription factors and many metabolic pathways, but contain expansions of surface proteins, especially a unique and complex surface glycoprotein superfamily, as well as proteases and RNA processing proteins. Unexpectedly, the key fungal cell wall components chitin and outer chain N-mannans are absent, based on genome content and experimental validation. Our findings suggest that Pneumocystis has developed unique mechanisms of adaptation to life exclusively in mammalian hosts, including dependence on the lungs for gas and nutrients and highly efficient strategies to escape both host innate and acquired immune defenses. PMID:26899007

  2. Genome analysis of three Pneumocystis species reveals adaptation mechanisms to life exclusively in mammalian hosts

    PubMed Central

    Ma, Liang; Chen, Zehua; Huang, Da Wei; Kutty, Geetha; Ishihara, Mayumi; Wang, Honghui; Abouelleil, Amr; Bishop, Lisa; Davey, Emma; Deng, Rebecca; Deng, Xilong; Fan, Lin; Fantoni, Giovanna; Fitzgerald, Michael; Gogineni, Emile; Goldberg, Jonathan M.; Handley, Grace; Hu, Xiaojun; Huber, Charles; Jiao, Xiaoli; Jones, Kristine; Levin, Joshua Z.; Liu, Yueqin; Macdonald, Pendexter; Melnikov, Alexandre; Raley, Castle; Sassi, Monica; Sherman, Brad T.; Song, Xiaohong; Sykes, Sean; Tran, Bao; Walsh, Laura; Xia, Yun; Yang, Jun; Young, Sarah; Zeng, Qiandong; Zheng, Xin; Stephens, Robert; Nusbaum, Chad; Birren, Bruce W.; Azadi, Parastoo; Lempicki, Richard A.; Cuomo, Christina A.; Kovacs, Joseph A.

    2016-01-01

    Pneumocystis jirovecii is a major cause of life-threatening pneumonia in immunosuppressed patients including transplant recipients and those with HIV/AIDS, yet surprisingly little is known about the biology of this fungal pathogen. Here we report near complete genome assemblies for three Pneumocystis species that infect humans, rats and mice. Pneumocystis genomes are highly compact relative to other fungi, with substantial reductions of ribosomal RNA genes, transporters, transcription factors and many metabolic pathways, but contain expansions of surface proteins, especially a unique and complex surface glycoprotein superfamily, as well as proteases and RNA processing proteins. Unexpectedly, the key fungal cell wall components chitin and outer chain N-mannans are absent, based on genome content and experimental validation. Our findings suggest that Pneumocystis has developed unique mechanisms of adaptation to life exclusively in mammalian hosts, including dependence on the lungs for gas and nutrients and highly efficient strategies to escape both host innate and acquired immune defenses. PMID:26899007

  3. Cisplatin resistance: a cellular self-defense mechanism resulting from multiple epigenetic and genetic changes.

    PubMed

    Shen, Ding-Wu; Pouliot, Lynn M; Hall, Matthew D; Gottesman, Michael M

    2012-07-01

    Cisplatin is one of the most effective broad-spectrum anticancer drugs. Its effectiveness seems to be due to the unique properties of cisplatin, which enters cells via multiple pathways and forms multiple different DNA-platinum adducts while initiating a cellular self-defense system by activating or silencing a variety of different genes, resulting in dramatic epigenetic and/or genetic alternations. As a result, the development of cisplatin resistance in human cancer cells in vivo and in vitro by necessity stems from bewilderingly complex genetic and epigenetic changes in gene expression and alterations in protein localization. Extensive published evidence has demonstrated that pleiotropic alterations are frequently detected during development of resistance to this toxic metal compound. Changes occur in almost every mechanism supporting cell survival, including cell growth-promoting pathways, apoptosis, developmental pathways, DNA damage repair, and endocytosis. In general, dozens of genes are affected in cisplatin-resistant cells, including pathways involved in copper metabolism as well as transcription pathways that alter the cytoskeleton, change cell surface presentation of proteins, and regulate epithelial-to-mesenchymal transition. Decreased accumulation is one of the most common features resulting in cisplatin resistance. This seems to be a consequence of numerous epigenetic and genetic changes leading to the loss of cell-surface binding sites and/or transporters for cisplatin, and decreased fluid phase endocytosis. PMID:22659329

  4. A proteomics perspective on viral DNA sensors in host defense and viral immune evasion mechanisms.

    PubMed

    Crow, Marni S; Javitt, Aaron; Cristea, Ileana M

    2015-06-01

    The sensing of viral DNA is an essential step of cellular immune response to infections with DNA viruses. These human pathogens are spread worldwide, triggering a wide range of virus-induced diseases, and are associated with high levels of morbidity and mortality. Despite similarities between DNA molecules, mammalian cells have the remarkable ability to distinguish viral DNA from their own DNA. This detection is carried out by specialized antiviral proteins, called DNA sensors. These sensors bind to foreign DNA to activate downstream immune signaling pathways and alert neighboring cells by eliciting the expression of antiviral cytokines. The sensing of viral DNA was shown to occur both in the cytoplasm and in the nucleus of infected cells, disproving the notion that sensing occurred by simple spatial separation of viral and host DNA. A number of omic approaches, in particular, mass-spectrometry-based proteomic methods, have significantly contributed to the constantly evolving field of viral DNA sensing. Here, we review the impact of omic methods on the identification of viral DNA sensors, as well as on the characterization of mechanisms involved in host defense or viral immune evasion.

  5. Cisplatin Resistance: A Cellular Self-Defense Mechanism Resulting from Multiple Epigenetic and Genetic Changes

    PubMed Central

    Shen, Ding-Wu; Pouliot, Lynn M.; Hall, Matthew D.

    2012-01-01

    Cisplatin is one of the most effective broad-spectrum anticancer drugs. Its effectiveness seems to be due to the unique properties of cisplatin, which enters cells via multiple pathways and forms multiple different DNA-platinum adducts while initiating a cellular self-defense system by activating or silencing a variety of different genes, resulting in dramatic epigenetic and/or genetic alternations. As a result, the development of cisplatin resistance in human cancer cells in vivo and in vitro by necessity stems from bewilderingly complex genetic and epigenetic changes in gene expression and alterations in protein localization. Extensive published evidence has demonstrated that pleiotropic alterations are frequently detected during development of resistance to this toxic metal compound. Changes occur in almost every mechanism supporting cell survival, including cell growth-promoting pathways, apoptosis, developmental pathways, DNA damage repair, and endocytosis. In general, dozens of genes are affected in cisplatin-resistant cells, including pathways involved in copper metabolism as well as transcription pathways that alter the cytoskeleton, change cell surface presentation of proteins, and regulate epithelial-to-mesenchymal transition. Decreased accumulation is one of the most common features resulting in cisplatin resistance. This seems to be a consequence of numerous epigenetic and genetic changes leading to the loss of cell-surface binding sites and/or transporters for cisplatin, and decreased fluid phase endocytosis. PMID:22659329

  6. UVR defense mechanisms in eurytopic and invasive Gracilaria vermiculophylla (Gracilariales, Rhodophyta).

    PubMed

    Roleda, Michael Y; Nyberg, Cecilia D; Wulff, Angela

    2012-10-01

    The invasive success of Gracilaria vermiculophylla has been attributed to its wide tolerance range to different abiotic factors, but its response to ultraviolet radiation (UVR) is yet to be investigated. In the laboratory, carpospores and vegetative thalli of an Atlantic population were exposed to different radiation treatments consisting of high PAR (photosynthetically active radiation) only (P), PAR+UV-A (PA) and PAR+UV-A+UV-B (PAB). Photosynthesis of carpospores was photoinhibited under different radiation treatments but photosystem II (PSII) function was restored after 12 h under dim white light. Growth of vegetative thalli was significantly higher under radiation supplemented with UVR. Decrease in chlorophyll a (Chl a) under daily continuous 16-h exposure to 300 µmol photons m(-2) s(-1) of PAR suggests preventive accumulation of excited chlorophyll molecules within the antennae to minimize the generation of dangerous reactive oxygen species. Moreover, an increase in total carotenoids and xanthophyll cycle pigments (i.e. violaxanthin, antheraxanthin and zeaxanthin) further suggests effective photoprotection under UVR. The presence of the ketocarotenoid β-cryptoxanthin also indicates protection against UVR and oxidative stress. The initial concentration of total mycosporine-like amino acids (MAAs) in freshly-released spores increased approximately four times after 8-h laboratory radiation treatments. On the other hand, initial specific MAAs in vegetative thalli changed in composition after 7-day exposure to laboratory radiation conditions without affecting the total concentration. The above responses suggest that G. vermiculophylla have multiple UVR defense mechanisms to cope with the dynamic variation in light quantity and quality encountered in its habitat. Beside being eurytopic, the UVR photoprotective mechanisms likely contribute to the current invasive success of the species in shallow lagoons and estuaries exposed to high solar radiation. PMID:22420775

  7. UVR defense mechanisms in eurytopic and invasive Gracilaria vermiculophylla (Gracilariales, Rhodophyta).

    PubMed

    Roleda, Michael Y; Nyberg, Cecilia D; Wulff, Angela

    2012-10-01

    The invasive success of Gracilaria vermiculophylla has been attributed to its wide tolerance range to different abiotic factors, but its response to ultraviolet radiation (UVR) is yet to be investigated. In the laboratory, carpospores and vegetative thalli of an Atlantic population were exposed to different radiation treatments consisting of high PAR (photosynthetically active radiation) only (P), PAR+UV-A (PA) and PAR+UV-A+UV-B (PAB). Photosynthesis of carpospores was photoinhibited under different radiation treatments but photosystem II (PSII) function was restored after 12 h under dim white light. Growth of vegetative thalli was significantly higher under radiation supplemented with UVR. Decrease in chlorophyll a (Chl a) under daily continuous 16-h exposure to 300 µmol photons m(-2) s(-1) of PAR suggests preventive accumulation of excited chlorophyll molecules within the antennae to minimize the generation of dangerous reactive oxygen species. Moreover, an increase in total carotenoids and xanthophyll cycle pigments (i.e. violaxanthin, antheraxanthin and zeaxanthin) further suggests effective photoprotection under UVR. The presence of the ketocarotenoid β-cryptoxanthin also indicates protection against UVR and oxidative stress. The initial concentration of total mycosporine-like amino acids (MAAs) in freshly-released spores increased approximately four times after 8-h laboratory radiation treatments. On the other hand, initial specific MAAs in vegetative thalli changed in composition after 7-day exposure to laboratory radiation conditions without affecting the total concentration. The above responses suggest that G. vermiculophylla have multiple UVR defense mechanisms to cope with the dynamic variation in light quantity and quality encountered in its habitat. Beside being eurytopic, the UVR photoprotective mechanisms likely contribute to the current invasive success of the species in shallow lagoons and estuaries exposed to high solar radiation.

  8. The Role of Defense Mechanisms, Personality and Demographical Factors on Complicated Grief following Death of a loved one by Cancer

    PubMed Central

    Rahimian Boogar, Isaac; Talepasand, Siavash

    2015-01-01

    Objective: Identification of the risk factors and psychological correlates of prolonged grief disorder is vital for health promotions in relatives of persons who died of cancer. The aim of this research was to investigate the role of defense mechanisms, character dimension of personality and demographic factors on complicated grief following a loss of a family member to cancer. Method: A number of 226 persons who had lost a family member to cancer in a cancer institute at Tehran University of Medical Science were selected through compliance sampling and completed the Inventory of complicated Grief-Revised (ICG-R), the Defense Styles Questionnaire (DSQ), the Character dimension of Temperament and Character Inventory (TCI), and the Demographical questionnaire. Data were analyzed by stepwise multiple regression analysis, using the PASW version 18. Results: Findings revealed that neurotic defense style had a significant positive predictive role in the complicated grief; and cooperativeness, age of the deceased person, self-transcendence and mature defense style had a significant negative predictive role in complicated grief (p<0.001). R2 was 0.73 for the final model (p<.001). Conclusion: The results revealed that two character dimensions (low cooperativeness and self-transcendence), high neurotic defense style and young age of the deceased person were involved in the psychopathological course of the complicated and prolonged grief. It was concluded that personality characteristics of the grieving persons and demographics of the deceased person should be addressed in designing tailored interventions for complicated grief. PMID:26884783

  9. In vivo deployment of mechanically adaptive nanocomposites for intracortical microelectrodes

    PubMed Central

    Harris, J P; Hess, A E; Rowan, S J; Weder, C; Zorman, C A; Tyler, D J; Capadona, J R

    2012-01-01

    We recently introduced a series of stimuli-responsive, mechanically-adaptive polymer nanocomposites. Here, we report the first application of these bio-inspired materials as substrates for intracortical microelectrodes. Our hypothesis is that the ideal electrode should be initially stiff to facilitate minimal trauma during insertion into the cortex, yet becomes mechanically compliant to match the stiffness of the brain tissue and minimize forces exerted on the tissue, attenuating inflammation. Microprobes created from mechanically reinforced nanocomposites demonstrated a significant advantage compared to model microprobes composed of neat polymer only. The nanocomposite microprobes exhibit a higher storage modulus (E’ = ~5 GPa) than the neat polymer microprobes (E’ = ~2 GPa) and could sustain higher loads (~17 mN), facilitating penetration through the pia mater and insertion into the cerebral cortex of a rat. In contrast, the neat polymer microprobes mechanically failed under lower loads (~7 mN) before they were capable of inserting into cortical tissue. Further, we demonstrated the material’s ability to morph while in the rat cortex to more closely match the mechanical properties of the cortical tissue. Nanocomposite microprobes that were implanted into the rat cortex for up to 8 weeks demonstrated increased cell density at the microelectrode-tissue interface and a lack of tissue necrosis or excessive gliosis. This body of work introduces our nanocomposite-based microprobes as adaptive substrates for intracortical microelectrodes and potentially other biomedical applications. PMID:21654037

  10. In vivo deployment of mechanically adaptive nanocomposites for intracortical microelectrodes.

    PubMed

    Harris, J P; Hess, A E; Rowan, S J; Weder, C; Zorman, C A; Tyler, D J; Capadona, J R

    2011-08-01

    We recently introduced a series of stimuli-responsive, mechanically adaptive polymer nanocomposites. Here, we report the first application of these bio-inspired materials as substrates for intracortical microelectrodes. Our hypothesis is that the ideal electrode should be initially stiff to facilitate minimal trauma during insertion into the cortex, yet become mechanically compliant to match the stiffness of the brain tissue and minimize forces exerted on the tissue, attenuating inflammation. Microprobes created from mechanically reinforced nanocomposites demonstrated a significant advantage compared to model microprobes composed of neat polymer only. The nanocomposite microprobes exhibit a higher storage modulus (E' = ~5 GPa) than the neat polymer microprobes (E' = ~2 GPa) and can sustain higher loads (~12 mN), facilitating penetration through the pia mater and insertion into the cerebral cortex of a rat. In contrast, the neat polymer microprobes mechanically failed under lower loads (~7 mN) before they were capable of insertion into cortical tissue. Further, we demonstrated the material's ability to morph while in the rat cortex to more closely match the mechanical properties of the cortical tissue. Nanocomposite microprobes that were implanted into the rat cortex for up to eight weeks demonstrated increased cell density at the microelectrode-tissue interface and a lack of tissue necrosis or excessive gliosis. This body of work introduces our nanocomposite-based microprobes as adaptive substrates for intracortical microelectrodes and potentially for other biomedical applications.

  11. A Shortened Norwegian Adaptation of the Lie Scale for Children (LSC) and the Defensiveness Scale for Children (DSC)

    ERIC Educational Resources Information Center

    Haugen, Richard

    1978-01-01

    Ten items consisting of five DSC items and five LSC items were translated into Norwegian in order (a) to control the verbal anxiety responses from defensive tendencies, (b) to handle the problem of response set (the tendency to answer a questionnaire in a stereotyped way), and (c) to permit research concerning the nature of defensiveness itself.…

  12. Explicit mentalizing mechanisms and their adaptive role in memory conformity.

    PubMed

    Wheeler, Rebecca; Allan, Kevin; Tsivilis, Dimitris; Martin, Douglas; Gabbert, Fiona

    2013-01-01

    Memory conformity occurs when an individual endorses what other individuals remember about past events. Research on memory conformity is currently dominated by a 'forensic' perspective, which views the phenomenon as inherently undesirable. This is because conformity not only distorts the accuracy of an individual's memory, but also produces false corroboration between individuals, effects that act to undermine criminal justice systems. There is growing awareness, however, that memory conformity may be interpreted more generally as an adaptive social behavior regulated by explicit mentalizing mechanisms. Here, we provide novel evidence in support of this emerging alternative theoretical perspective. We carried out a memory conformity experiment which revealed that explicit belief-simulation (i.e. using one's own beliefs to model what other people believe) systematically biases conformity towards like-minded individuals, even when there is no objective evidence that they have a more accurate memory than dissimilar individuals. We suggest that this bias is functional, i.e. adaptive, to the extent that it fosters trust, and hence cooperation, between in-group versus out-group individuals. We conclude that memory conformity is, in more fundamental terms, a highly desirable product of explicit mentalizing mechanisms that promote adaptive forms of social learning and cooperation.

  13. Bacterial meningitis in the patient at risk: intrinsic risk factors and host defense mechanisms.

    PubMed

    Scheld, W M

    1984-05-15

    Bacterial meningitis remains a relatively common disease worldwide (40,000 cases per year in the United States) and the mortality rate has not improved in over 30 years. Certain host factors increase the risk of acquiring meningitis and include: age (increased at extremes of life), male sex, low socioeconomic status (crowding), black race, recent nasopharyngeal carriage of a virulent strain, absence of specific bactericidal antibody, maternal factors at birth (neonatal disease), various immunologic defects (neonates, antibody or terminal complement component deficiency, splenectomy, and immunosuppression including the acquired immune deficiency syndrome), and certain chronic diseases (such as alcoholism, cirrhosis, and diabetes mellitus). Bacterial meningitis represents an infection in an area of impaired host resistance. The blood-brain barrier is a major protective mechanism for the central nervous system against circulating bacteria. However, once bacteria gain entry into the subarachnoid space, host defenses are inadequate. Polymorphonuclear leukocytes are at a disadvantage in the fluid medium of the cerebrospinal fluid and surface phagocytosis is inefficient. In addition, antibody and complement concentrations are low (or absent) in purulent cerebrospinal fluid early in the disease course. Functional opsonic and bactericidal activity is lacking; therefore, efficient phagocytosis of encapsulated meningeal pathogens is limited. The result is huge population densities (often 10(7) to 10(8) cfu per milliliter) of bacteria in cerebrospinal fluid. This finding suggests that bactericidal antibiotics with cerebrospinal fluid concentrations much greater than the minimal bacterial concentration of the pathogen are optimal for therapy of meningitis; this principle has been shown in experimental animal models and supported by therapeutic studies in human subjects.

  14. Application of flexure structures to active and adaptive opto-mechanical mechanisms

    NASA Astrophysics Data System (ADS)

    Zago, Lorenzo; Genequand, Pierre M.; Kjelberg, Ivar; Morschel, Joseph

    1997-03-01

    Active and adaptive structures, also commonly called 'smart' structures, combine in one integrated system various functions such as load carrying and structural function, mechanical (cinematic) functions, sensing, control and actuating. Originally developed for high accuracy opto-mechanical applications, CSEM's technology of flexure structures and flexible mechanisms is particularly suited to solve many structural and mechanical issues found in such active/adaptive mechanisms. The paper illustrates some recent flexure structures developments at CSEM and outlines the comprehensive know-how involved in this technology. This comprises in particular the elaboration of optimal design guidelines, related to the geometry, kinematics and dynamics issues (for instance, the minimization of spurious high frequency effects), the evaluation and predictability of all performance quantities relevant to the utilization of flexure structures in space (reliability, fatigue, static and dynamic modeling, etc.). material issues and manufacturing procedures.

  15. Mechanisms in Adaptive Feedback Control: Photoisomerization in a Liquid

    SciTech Connect

    Hoki, Kunihito; Brumer, Paul

    2005-10-14

    The underlying mechanism for Adaptive Feedback Control in the experimental photoisomerization of 3,3'-diethyl-2,2'-thiacyanine iodide (NK88) in methanol is exposed theoretically. With given laboratory limitations on laser output, the complicated electric fields are shown to achieve their targets in qualitatively simple ways. Further, control over the cis population without laser limitations reveals an incoherent pump-dump scenario as the optimal isomerization strategy. In neither case are there substantial contributions from quantum multiple-path interference or from nuclear wave packet coherence. Environmentally induced decoherence is shown to justify the use of a simplified theoretical model.

  16. Aneuploidy as a mechanism for stress-induced liver adaptation

    PubMed Central

    Duncan, Andrew W.; Hanlon Newell, Amy E.; Bi, Weimin; Finegold, Milton J.; Olson, Susan B.; Beaudet, Arthur L.; Grompe, Markus

    2012-01-01

    Over half of the mature hepatocytes in mice and humans are aneuploid and yet retain full ability to undergo mitosis. This observation has raised the question of whether this unusual somatic genetic variation evolved as an adaptive mechanism in response to hepatic injury. According to this model, hepatotoxic insults select for hepatocytes with specific numerical chromosome abnormalities, rendering them differentially resistant to injury. To test this hypothesis, we utilized a strain of mice heterozygous for a mutation in the homogentisic acid dioxygenase (Hgd) gene located on chromosome 16. Loss of the remaining Hgd allele protects from fumarylacetoacetate hydrolase (Fah) deficiency, a genetic liver disease model. When adult mice heterozygous for Hgd and lacking Fah were exposed to chronic liver damage, injury-resistant nodules consisting of Hgd-null hepatocytes rapidly emerged. To determine whether aneuploidy played a role in this phenomenon, array comparative genomic hybridization (aCGH) and metaphase karyotyping were performed. Strikingly, loss of chromosome 16 was dramatically enriched in all mice that became completely resistant to tyrosinemia-induced hepatic injury. The frequency of chromosome 16–specific aneuploidy was approximately 50%. This result indicates that selection of a specific aneuploid karyotype can result in the adaptation of hepatocytes to chronic liver injury. The extent to which aneuploidy promotes hepatic adaptation in humans remains under investigation. PMID:22863619

  17. Aneuploidy as a mechanism for stress-induced liver adaptation.

    PubMed

    Duncan, Andrew W; Hanlon Newell, Amy E; Bi, Weimin; Finegold, Milton J; Olson, Susan B; Beaudet, Arthur L; Grompe, Markus

    2012-09-01

    Over half of the mature hepatocytes in mice and humans are aneuploid and yet retain full ability to undergo mitosis. This observation has raised the question of whether this unusual somatic genetic variation evolved as an adaptive mechanism in response to hepatic injury. According to this model, hepatotoxic insults select for hepatocytes with specific numerical chromosome abnormalities, rendering them differentially resistant to injury. To test this hypothesis, we utilized a strain of mice heterozygous for a mutation in the homogentisic acid dioxygenase (Hgd) gene located on chromosome 16. Loss of the remaining Hgd allele protects from fumarylacetoacetate hydrolase (Fah) deficiency, a genetic liver disease model. When adult mice heterozygous for Hgd and lacking Fah were exposed to chronic liver damage, injury-resistant nodules consisting of Hgd-null hepatocytes rapidly emerged. To determine whether aneuploidy played a role in this phenomenon, array comparative genomic hybridization (aCGH) and metaphase karyotyping were performed. Strikingly, loss of chromosome 16 was dramatically enriched in all mice that became completely resistant to tyrosinemia-induced hepatic injury. The frequency of chromosome 16-specific aneuploidy was approximately 50%. This result indicates that selection of a specific aneuploid karyotype can result in the adaptation of hepatocytes to chronic liver injury. The extent to which aneuploidy promotes hepatic adaptation in humans remains under investigation.

  18. From emotional abuse in childhood to psychopathology in adulthood: a path mediated by immature defense mechanisms and self-esteem.

    PubMed

    Finzi-Dottan, Ricky; Karu, Toby

    2006-08-01

    The present study examined the course traveled from childhood emotional abuse to adulthood psychopathology. One hundred ninety-six undergraduate students age 20 to 45 (M = 27; SD = 8.17), answered self-report questionnaires assessing emotional abuse in childhood (Childhood Trauma Questionnaire), parental attitudes (Parental Bonding Instrument), psychopathological symptomatology (Brief Symptom Inventory), self-esteem (Rosenberg Self-Esteem Scale), and defense mechanism organization (Defense Style Questionnaire). Results indicated that reported psychopathological symptomatology highly exceeded the Israeli norm. Structure Equation Modeling provided a statistically significant explanation (52%) of the target variable of psychopathological symptomatology. According to the path model, emotional abuse in childhood and perceptions of controlling and noncaring parents had an indirect effect on the psychopathology. This was mediated by immature defenses and low self-esteem. We conclude that the manifest psychopathology among adults who suffered emotional abuse in childhood is produced by the detrimental effect of abuse on personality, and takes the form of immature defense organization and damaged self-representation.

  19. MECHANISMS OF STATIONARY PHASE MUTATION: A Decade of Adaptive Mutation

    PubMed Central

    Foster, P. L.

    2010-01-01

    A decade of research on adaptive mutation has revealed a plethora of mutagenic mechanisms that may be important in evolution. The DNA synthesis associated with recombination could be an important source of spontaneous mutation in cells that are not proliferating. The movement of insertion elements can be responsive to environmental conditions. Insertion elements not only activate and inactivate genes, they also provide sequence homology that allows large-scale genomic rearrangements. Some conjugative plasmids can recombine with their host’s chromosome, and may acquire chromosomal genes that could then spread through the population and even to other species. Finally, a subpopulation of transient hypermutators could be a source of multiple variant alleles, providing a mechanism for rapid evolution under adverse conditions. PMID:10690404

  20. Adaptive mechanisms of Campylobacter jejuni to erythromycin treatment

    PubMed Central

    2013-01-01

    Background Macrolide is the drug of choice to treat human campylobacteriosis, but Campylobacter resistance to this antibiotic is rising. The mechanisms employed by Campylobacter jejuni to adapt to erythromycin treatment remain unknown and are examined in this study. The transcriptomic response of C. jejuni NCTC 11168 to erythromycin (Ery) treatment was determined by competitive microarray hybridizations. Representative genes identified to be differentially expressed were further characterized by constructing mutants and assessing their involvement in antimicrobial susceptibility, oxidative stress tolerance, and chicken colonization. Results Following the treatment with an inhibitory dose of Ery, 139 genes were up-regulated and 119 were down-regulated. Many genes associated with flagellar biosynthesis and motility was up-regulated, while many genes involved in tricarboxylic acid cycle, electron transport, and ribonucleotide biosynthesis were down-regulated. Exposure to a sub-inhibitory dose of Ery resulted in differential expression of much fewer genes. Interestingly, two putative drug efflux operons (cj0309c-cj0310c and cj1173-cj1174) were up-regulated. Although mutation of the two operons did not alter the susceptibility of C. jejuni to antimicrobials, it reduced Campylobacter growth under high-level oxygen. Another notable finding is the consistent up-regulation of cj1169c-cj1170c, of which cj1170c encodes a known phosphokinase, an important regulatory protein in C. jejuni. Mutation of the cj1169c-cj1170c rendered C. jejuni less tolerant to atmospheric oxygen and reduced Campylobacter colonization and transmission in chickens. Conclusions These findings indicate that Ery treatment elicits a range of changes in C. jejuni transcriptome and affects the expression of genes important for in vitro and in vivo adaptation. Up-regulation of motility and down-regulation of energy metabolism likely facilitate Campylobacter to survive during Ery treatment. These findings

  1. Zinc triggers signaling mechanisms and defense responses promoting resistance to Alternaria brassicicola in Arabidopsis thaliana.

    PubMed

    Martos, Soledad; Gallego, Berta; Cabot, Catalina; Llugany, Mercè; Barceló, Juan; Poschenrieder, Charlotte

    2016-08-01

    According to the elemental defense hypothesis the accumulation of trace elements by plants may substitute for organic defenses, while the joint effects hypothesis proposes that trace elements and organic defenses can have additive or synergistic effects against pathogens or herbivores. To evaluate these hypotheses the response of the pathosystem Alternaria brassicicola-Arabidopsis thaliana to control (2μM) and surplus (12μM) Zn was evaluated using the camalexin deficient mutant pad3-1 and mtp1-1, a mutant with impaired Zn vacuolar storage, along with the corresponding wildtypes. In vitro, a 50% inhibition of fungal growth was achieved by 440μM Zn. A. thaliana leaves could accumulate equivalent concentrations without harm. In fact, surplus Zn enhanced the resistance of A. thaliana to fungal attack in Columbia (Col-0), Wassilewskija (WS), and mtp1-1. However, surplus Zn was unable to protect pad3-1 demonstrating that Zn cannot substitute for camalexin, the main organic defense in A. thaliana. High, non phytotoxic leaf Zn concentrations enhanced the resistance to A. brassicicola of A. thaliana genotypes able to produce camalexin. This was mainly due to Zn-induced enhancement of the JA/ETH signaling pathway leading to enhanced PAD3 expression. These results support the joint effects hypothesis and highlight the importance of adequate Zn supply for reinforced pathogen resistance. PMID:27297986

  2. A density-based adaptive quantum mechanical/molecular mechanical method.

    PubMed

    Waller, Mark P; Kumbhar, Sadhana; Yang, Jack

    2014-10-20

    We present a density-based adaptive quantum mechanical/molecular mechanical (DBA-QM/MM) method, whereby molecules can switch layers from the QM to the MM region and vice versa. The adaptive partitioning of the molecular system ensures that the layer assignment can change during the optimization procedure, that is, on the fly. The switch from a QM molecule to a MM molecule is determined if there is an absence of noncovalent interactions to any atom of the QM core region. The presence/absence of noncovalent interactions is determined by analysis of the reduced density gradient. Therefore, the location of the QM/MM boundary is based on physical arguments, and this neatly removes some empiricism inherent in previous adaptive QM/MM partitioning schemes. The DBA-QM/MM method is validated by using a water-in-water setup and an explicitly solvated L-alanyl-L-alanine dipeptide. PMID:24954803

  3. A density-based adaptive quantum mechanical/molecular mechanical method.

    PubMed

    Waller, Mark P; Kumbhar, Sadhana; Yang, Jack

    2014-10-20

    We present a density-based adaptive quantum mechanical/molecular mechanical (DBA-QM/MM) method, whereby molecules can switch layers from the QM to the MM region and vice versa. The adaptive partitioning of the molecular system ensures that the layer assignment can change during the optimization procedure, that is, on the fly. The switch from a QM molecule to a MM molecule is determined if there is an absence of noncovalent interactions to any atom of the QM core region. The presence/absence of noncovalent interactions is determined by analysis of the reduced density gradient. Therefore, the location of the QM/MM boundary is based on physical arguments, and this neatly removes some empiricism inherent in previous adaptive QM/MM partitioning schemes. The DBA-QM/MM method is validated by using a water-in-water setup and an explicitly solvated L-alanyl-L-alanine dipeptide.

  4. High level resistance against rhizomania disease by simultaneously integrating two distinct defense mechanisms.

    PubMed

    Pavli, Ourania I; Tampakaki, Anastasia P; Skaracis, George N

    2012-01-01

    With the aim of achieving durable resistance against rhizomania disease of sugar beet, the employment of different sources of resistance to Beet necrotic yellow vein virus was pursued. To this purpose, Nicotiana benthamiana transgenic plants that simultaneously produce dsRNA originating from a conserved region of the BNYVV replicase gene and the HrpZ(Psph) protein in a secreted form (SP/HrpZ(Psph)) were produced. The integration and expression of both transgenes as well as proper production of the harpin protein were verified in all primary transformants and selfed progeny (T1, T2). Transgenic resistance was assessed by BNYVV-challenge inoculation on T2 progeny by scoring disease symptoms and DAS-ELISA at 20 and 30 dpi. Transgenic lines possessing single transformation events for both transgenes as well as wild type plants were included in inoculation experiments. Transgenic plants were highly resistant to virus infection, whereas in some cases immunity was achieved. In all cases, the resistant phenotype of transgenic plants carrying both transgenes was superior in comparison with the ones carrying a single transgene. Collectively, our findings demonstrate, for a first time, that the combination of two entirely different resistance mechanisms provide high level resistance or even immunity against the virus. Such a novel approach is anticipated to prevent a rapid virus adaptation that could potentially lead to the emergence of isolates with resistance breaking properties.

  5. High level resistance against rhizomania disease by simultaneously integrating two distinct defense mechanisms.

    PubMed

    Pavli, Ourania I; Tampakaki, Anastasia P; Skaracis, George N

    2012-01-01

    With the aim of achieving durable resistance against rhizomania disease of sugar beet, the employment of different sources of resistance to Beet necrotic yellow vein virus was pursued. To this purpose, Nicotiana benthamiana transgenic plants that simultaneously produce dsRNA originating from a conserved region of the BNYVV replicase gene and the HrpZ(Psph) protein in a secreted form (SP/HrpZ(Psph)) were produced. The integration and expression of both transgenes as well as proper production of the harpin protein were verified in all primary transformants and selfed progeny (T1, T2). Transgenic resistance was assessed by BNYVV-challenge inoculation on T2 progeny by scoring disease symptoms and DAS-ELISA at 20 and 30 dpi. Transgenic lines possessing single transformation events for both transgenes as well as wild type plants were included in inoculation experiments. Transgenic plants were highly resistant to virus infection, whereas in some cases immunity was achieved. In all cases, the resistant phenotype of transgenic plants carrying both transgenes was superior in comparison with the ones carrying a single transgene. Collectively, our findings demonstrate, for a first time, that the combination of two entirely different resistance mechanisms provide high level resistance or even immunity against the virus. Such a novel approach is anticipated to prevent a rapid virus adaptation that could potentially lead to the emergence of isolates with resistance breaking properties. PMID:23284692

  6. Brief Report: Self-Harm Is Associated with Immature Defense Mechanisms but Not Substance Use in a Nonclinical Scottish Adolescent Sample

    ERIC Educational Resources Information Center

    Brody, Stuart; Carson, Carron Maryjane

    2012-01-01

    It has been unclear whether adolescent deliberate self-harm (DSH) is more associated with substance use or with characterological impairments. Multivariate determination of (N = 114 Scottish adolescents) ever engaging in DSH (Youth Risk Behavior Survey) from alcohol use, other substance use, and immature defense mechanism use (Defense Style…

  7. Defense use and defense understanding in children.

    PubMed

    Cramer, P; Brilliant, M A

    2001-04-01

    This study investigated the relation between children's use of defense mechanisms and their understanding of those defenses. We hypothesized that, once a child understands how a particular defense functions, the use of that defense will no longer be successful and will be replaced by another defense mechanism that is not yet understood. Defense use was assessed from the Thematic Appreception Test (TAT) stories told by 122 children; defense understanding was determined from the children's understanding of stories portraying defenses. The results indicated that younger children (mean age = 7-8) used the defense of denial more than the older children (mean age = 9-11). Older children understood the functioning of denial and projection better than the younger children. A comparison of children who did and did not understand a defense showed that younger children who understood the functioning of denial were less likely to themselves use denial. Likewise, older children who understood the functioning of projection were less likely to use this defense.

  8. The Integrity of the Esophageal Mucosa. Balance Between Offensive and Defensive Mechanisms

    PubMed Central

    Orlando, Roy C.

    2010-01-01

    Heartburn is the most common and characteristic symptom of gastroesophageal reflux disease. It ultimately results from contact of refluxed gastric acid with nociceptors within the esophageal mucosa and transmission of this peripheral signal to the central nervous system for cognition. Healthy esophageal epithelium provides an effective barrier between refluxed gastric acid and esophageal nociceptors; but this barrier is vulnerable to attack and damage, particularly by acidic gastric contents. How gastric acid is countered by defensive elements within the esophageal mucosa is a major focus of this discussion. When the defense is successful, the subject is asymptomatic and when unsuccessful, the subject experiences heartburn. Those with heartburn commonly fall into one of three endoscopic types: nonerosive reflux disease, erosive esophagitis and Barrett's esophagus. Although what determines endoscopic type remains unknown; it is proposed herein that inflammation plays a key, modulating role. PMID:21126700

  9. A genetic mechanism for Tibetan high-altitude adaptation

    PubMed Central

    Lorenzo, Felipe R; Huff, Chad; Myllymäki, Mikko; Olenchock, Benjamin; Swierczek, Sabina; Tashi, Tsewang; Gordeuk, Victor; Wuren, Tana; Ri-Li, Ge; McClain, Donald A; Khan, Tahsin M; Koul, Parvaiz A; Guchhait, Prasenjit; Salama, Mohamed E; Xing, Jinchuan; Semenza, Gregg L; Liberzon, Ella; Wilson, Andrew; Simonson, Tatum S; Jorde, Lynn B; Kaelin, William G; Koivunen, Peppi; Prchal, Josef T

    2015-01-01

    Tibetans do not exhibit increased hemoglobin concentration at high altitude. We describe a high-frequency missense mutation in the EGLN1 gene, which encodes prolyl hydroxylase 2 (PHD2), that contributes to this adaptive response. We show that a variant in EGLN1, c.[12C>G; 380G>C], contributes functionally to the Tibetan high-altitude phenotype. PHD2 triggers the degradation of hypoxia-inducible factors (HIFs), which mediate many physiological responses to hypoxia, including erythropoiesis. The PHD2 p.[Asp4Glu; Cys127Ser] variant exhibits a lower Km value for oxygen, suggesting that it promotes increased HIF degradation under hypoxic conditions. Whereas hypoxia stimulates the proliferation of wild-type erythroid progenitors, the proliferation of progenitors with the c.[12C>G; 380G>C] mutation in EGLN1 is significantly impaired under hypoxic culture conditions. We show that the c.[12C>G; 380G>C] mutation originated ~8,000 years ago on the same haplotype previously associated with adaptation to high altitude. The c.[12C>G; 380G>C] mutation abrogates hypoxia-induced and HIF-mediated augmentation of erythropoiesis, which provides a molecular mechanism for the observed protection of Tibetans from polycythemia at high altitude. PMID:25129147

  10. Molecular insights into mechanisms of lepidopteran serine proteinase resistance to natural plant defenses.

    PubMed

    Tamaki, Fábio K; Terra, Walter R

    2015-11-27

    Plants have a wide range of chemical defenses against predation, including substances that target digestive serine proteinases of herbivorous. Previous works demonstrated that lepidopteran insects have digestive serine proteinases resistant to plant proteinase inhibitors (PPIs) and ketone modifications, while coleopteran ones are sensitive to those plant defenses. This paper focuses on molecular aspects that lead lepidopteran serine proteinases to PPI and ketone modification resistance. Using biochemical experiments and computer 3D modeling we demonstrated that lepidopteran trypsins are more hydrophobic than coleopteran ones, a feature associated to trypsin oligomerization and decreased inhibition by PPI. Moreover, the determination of pKa values of chymotrypsin catalytic residues obtained by TPCK modification indicates that the environment around the active site of ketone-resistant and -sensitive chymotrypsins are different. Structural analysis using resistant and sensitive chymotrypsins data allowed us to point 2 hotspot regions around the active site that could explain the observed differences. Our set of results highlights features of serine proteinases important for understanding the resistance of insects to plant chemical defenses.

  11. Adaptive information interactive mechanism for multi-UAV visual navigation

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Dai, Qionghai

    2012-06-01

    Multi-unmanned aerial vehicle (UAV) cooperative communication for visual navigation has recently generated significant concern. It has large amounts of visual information to be transmitted and processed among UAVs with realtime requirements. And the UAV clusters have self-organized, time-varying and high dynamic characteristics. Considering the above conditions, we propose an adaptive information interactive mechanism (AIIM) for multi-UAV visual navigation. In the mechanism, the function modules for UAV inter-communication interface are designed, the mobility-based link lifetime is established and the information interactive protocol is presented. Thus we combine the mobility of UAVs with the corresponding communication requirements to make effective information interaction for UAVs. Task-oriented distributed control is adopted to improve the collaboration flexibility in the multi-UAV visual navigation system. In order to timely obtain the necessary visual information, each UAV can cooperate with other relevant UAVs which meet some certain terms such as situation, task or environmental conditions. Simulation results are presented to show the validity of the proposed mechanism in terms of end-to-end delay and links stability.

  12. Mechanisms of Cardiopulmonary Adaptation to Microgravity. Part 1

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Session TA1 includes short reports covering: (1) Indices of Baroreceptor Reflex Sensitivity: The Use in Rehabilitation Medicine and Space Cardiology; (2) +Gz and +Gx Tolerance of Healthy Persons of Non-Flying Trades at Primary Selection of the Centrifuge; (3) Effect of Dry Immersion on Calf Blood Supply During Sustained Contraction and Upright Exercise in Man; (4) Cardiovascular and Valsalva Responses during Parabolic flight; (5) An Analysis of the Cardiovascular Responses under Hyper- and Hypo-Gravity Environments using a Mathematical model; (6) Effect of Very Gradual Onset Rate +Gz Exposures on the Cardiovascular System; and (7) NASA Specialized Center of Research and Training (NSCORT) in Integrated Physiology: Mechanisms of Physiological Adaptations to Microgravity.

  13. Adaptive Broadcasting Mechanism for Bandwidth Allocation in Mobile Services

    PubMed Central

    Horng, Gwo-Jiun; Wang, Chi-Hsuan; Chou, Chih-Lun

    2014-01-01

    This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel's bandwidth and the data channel's bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice. PMID:25057509

  14. Adaptive broadcasting mechanism for bandwidth allocation in mobile services.

    PubMed

    Horng, Gwo-Jiun; Wang, Chi-Hsuan; Chou, Chih-Lun

    2014-01-01

    This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel's bandwidth and the data channel's bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice.

  15. Synaptic mechanisms of adaptation and sensitization in the retina

    PubMed Central

    Nikolaev, Anton; Leung, Kin-Mei; Odermatt, Benjamin; Lagnado, Leon

    2014-01-01

    Sensory systems continually adjust the way stimuli are processed. What are the circuit mechanisms underlying this plasticity? We investigated how synapses in the retina of zebrafish adjust to changes in the temporal contrast of a visual stimulus by imaging activity in vivo. Following an increase in contrast, bipolar cell synapses with strong initial responses depressed, whereas synapses with weak initial responses facilitated. Depression and facilitation predominated in different strata of the inner retina, where bipolar cell output was anticorrelated with the activity of amacrine cell synapses providing inhibitory feedback. Pharmacological block of GABAergic feedback converted facilitating bipolar cell synapses into depressing ones. These results indicate that depression intrinsic to bipolar cell synapses causes adaptation of the ganglion cell response to contrast, whereas depression in amacrine cell synapses causes sensitization. Distinct microcircuits segregating to different layers of the retina can cause simultaneous increases or decreases in the gain of neural responses. PMID:23685718

  16. Stochastic retinal mechanisms of light adaptation and gain control.

    PubMed

    Rudd, M E; Brown, L G

    1996-01-01

    Under appropriate experimental conditions, the threshold intensity of a visual stimulus varies as the square-root of the background illuminance. This square-root law has been observed in both psychophysical threshold experiments and in measurements of the thresholds of individual ganglion cells. A signal detection theory developed in the 1940s by H. L. de Vries and A. Rose, and since elaborated by H. B. Barlow and others, explains the square-root law on the basis of 'noise' due to fluctuations in the number of photon absorptions per unit area and unit time at the cornea. An alternative account of the square-root law--and also other threshold-vs-intensity slopes--is founded on the assumption of physiological gain control (W. A. H. Rushton, Proc, Roy. Soc. (London) B 162, 20-46, 1965; W. S. Geisler, J. Physiol. (London) 312, 165-179, 1979). In this paper, a neural model of light adaptation and gain control is described that shows how these two accounts of the square-root law can be reconciled by a stochastic gain control mechanism whose gain depends on the photon fluctuation level. The process by which spikes are generated in a ganglion cell is modeled in terms of a stochastic integrate-and-fire mechanism; this model is used to quantitatively fit toad retinal ganglion cell threshold data. A psychophysical model is then outlined showing how a statistical observer could analyze the ganglion cell spike trains generated by 'signal' and 'noise' trials in order to statistically discriminate the two conditions. The model is also shown to account for some dynamic aspects of ganglion cell responses, including ON- and OFF-responses. The neural light adaptation model predicts that--under the proper conditions--brightness matching judgments will also be subject to a square-root law. Experimental tests of the model under superthreshold conditions are proposed.

  17. Block-adaptive quantum mechanics: an adaptive divide-and-conquer approach to interactive quantum chemistry.

    PubMed

    Bosson, Maël; Grudinin, Sergei; Redon, Stephane

    2013-03-01

    We present a novel Block-Adaptive Quantum Mechanics (BAQM) approach to interactive quantum chemistry. Although quantum chemistry models are known to be computationally demanding, we achieve interactive rates by focusing computational resources on the most active parts of the system. BAQM is based on a divide-and-conquer technique and constrains some nucleus positions and some electronic degrees of freedom on the fly to simplify the simulation. As a result, each time step may be performed significantly faster, which in turn may accelerate attraction to the neighboring local minima. By applying our approach to the nonself-consistent Atom Superposition and Electron Delocalization Molecular Orbital theory, we demonstrate interactive rates and efficient virtual prototyping for systems containing more than a thousand of atoms on a standard desktop computer.

  18. Plant Defense Mechanisms Are Activated during Biotrophic and Necrotrophic Development of Colletotricum graminicola in Maize1[W][OA

    PubMed Central

    Vargas, Walter A.; Martín, José M. Sanz; Rech, Gabriel E.; Rivera, Lina P.; Benito, Ernesto P.; Díaz-Mínguez, José M.; Thon, Michael R.; Sukno, Serenella A.

    2012-01-01

    Hemibiotrophic plant pathogens first establish a biotrophic interaction with the host plant and later switch to a destructive necrotrophic lifestyle. Studies of biotrophic pathogens have shown that they actively suppress plant defenses after an initial microbe-associated molecular pattern-triggered activation. In contrast, studies of the hemibiotrophs suggest that they do not suppress plant defenses during the biotrophic phase, indicating that while there are similarities between the biotrophic phase of hemibiotrophs and biotrophic pathogens, the two lifestyles are not analogous. We performed transcriptomic, histological, and biochemical studies of the early events during the infection of maize (Zea mays) with Colletotrichum graminicola, a model pathosystem for the study of hemibiotrophy. Time-course experiments revealed that mRNAs of several defense-related genes, reactive oxygen species, and antimicrobial compounds all begin to accumulate early in the infection process and continue to accumulate during the biotrophic stage. We also discovered the production of maize-derived vesicular bodies containing hydrogen peroxide targeting the fungal hyphae. We describe the fungal respiratory burst during host infection, paralleled by superoxide ion production in specific fungal cells during the transition from biotrophy to a necrotrophic lifestyle. We also identified several novel putative fungal effectors and studied their expression during anthracnose development in maize. Our results demonstrate a strong induction of defense mechanisms occurring in maize cells during C. graminicola infection, even during the biotrophic development of the pathogen. We hypothesize that the switch to necrotrophic growth enables the fungus to evade the effects of the plant immune system and allows for full fungal pathogenicity. PMID:22247271

  19. Caspase-8 activity is part of the BeWo trophoblast cell defense mechanisms against Trypanosoma cruzi infection.

    PubMed

    Carrillo, Ileana; Droguett, Daniel; Castillo, Christian; Liempi, Ana; Muñoz, Lorena; Maya, Juan Diego; Galanti, Norbel; Kemmerling, Ulrike

    2016-09-01

    Congenital Chagas disease is caused by the protozoan parasite Trypanosoma cruzi that must cross the placental barrier during transmission. The trophoblast constitutes the first tissue in contact with the maternal-blood circulating parasite. Importantly, the congenital transmission rates are low, suggesting the presence of local placental defense mechanisms. Cellular proliferation and differentiation as well as apoptotic cell death are induced by the parasite and constitute part of the epithelial turnover of the trophoblast, which has been suggested to be part of those placental defenses. On the other hand, caspase-8 is an essential molecule in the modulation of trophoblast turnover by apoptosis and by epithelial differentiation. As an approach to study whether T. cruzi induced trophoblast turnover and infection is mediated by caspase-8, we infected BeWo cells (a trophoblastic cell line) with the parasite and determined in the infected cells the expression and enzymatic activity of caspase-8, DNA synthesis (as proliferation marker), β-human chorionic gonadotropin (β-hCG) (as differentiation marker) and activity of Caspase-3 (as apoptotic death marker). Parasite load in BeWo cells was measured by DNA quantification using qPCR and cell counting. Our results show that T. cruzi induces caspase-8 activity and that its inhibition increases trophoblast cells infection while decreases parasite induced cellular differentiation and apoptotic cell death, but not cellular proliferation. Thus, caspase-8 activity is part of the BeWo trophoblast cell defense mechanisms against T. cruzi infection. Together with our previous results, we suggest that the trophoblast turnover is part of local placental anti-parasite mechanisms.

  20. Clustered regularly interspaced short palindromic repeats (CRISPRs): the hallmark of an ingenious antiviral defense mechanism in prokaryotes.

    PubMed

    Al-Attar, Sinan; Westra, Edze R; van der Oost, John; Brouns, Stan J J

    2011-04-01

    Many prokaryotes contain the recently discovered defense system against mobile genetic elements. This defense system contains a unique type of repetitive DNA stretches, termed Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs). CRISPRs consist of identical repeated DNA sequences (repeats), interspaced by highly variable sequences referred to as spacers. The spacers originate from either phages or plasmids and comprise the prokaryotes' 'immunological memory'. CRISPR-associated (cas) genes encode conserved proteins that together with CRISPRs make-up the CRISPR/Cas system, responsible for defending the prokaryotic cell against invaders. CRISPR-mediated resistance has been proposed to involve three stages: (i) CRISPR-Adaptation, the invader DNA is encountered by the CRISPR/Cas machinery and an invader-derived short DNA fragment is incorporated in the CRISPR array. (ii) CRISPR-Expression, the CRISPR array is transcribed and the transcript is processed by Cas proteins. (iii) CRISPR-Interference, the invaders' nucleic acid is recognized by complementarity to the crRNA and neutralized. An application of the CRISPR/Cas system is the immunization of industry-relevant prokaryotes (or eukaryotes) against mobile-genetic invasion. In addition, the high variability of the CRISPR spacer content can be exploited for phylogenetic and evolutionary studies. Despite impressive progress during the last couple of years, the elucidation of several fundamental details will be a major challenge in future research.

  1. [Insulin resistance as a mechanism of adaptation during human evolution].

    PubMed

    Ricart, W; Fernández-Real, J M

    2010-10-01

    The recent application of concepts of evolution to human disease is proving useful to understand certain pathophysiological mechanisms of different entities that span genomic alterations of immunity, respiratory and hormone function, and the circulatory and neural systems. However, effort has concentrated on explaining the keys to adaptation that define human metabolism and, since the early 1960s, several theories have been developed. This article reviews some of the hypotheses postulated in recent years on the potential benefit of insulin resistance and discusses the most recent knowledge. The concept of the thrifty gene seems to have been definitively refuted by current knowledge. The current paradigm describes an interaction between the metabolic and the immune systems resulting from their coevolution, promoted by evolutionary pressures triggered by fasting, infection and intake of different foods. The activation and regulation of these ancient mechanisms in integrated and interdependent areas defines insulin resistance as a survival strategy that is critical during fasting and in the fight against infection. The relationship with some components of the diet and, particularly, with the symbiotic intestinal microflora points to new paradigms in understanding the pathophysiology of obesity, metabolic syndrome and type 2 diabetes mellitus.

  2. Molecular mechanisms of Tetranychus urticae chemical adaptation in hop fields

    PubMed Central

    Piraneo, Tara G.; Bull, Jon; Morales, Mariany A.; Lavine, Laura C.; Walsh, Douglas B.; Zhu, Fang

    2015-01-01

    The two-spotted spider mite, Tetranychus urticae Koch is a major pest that feeds on >1,100 plant species. Many perennial crops including hop (Humulus lupulus) are routinely plagued by T. urticae infestations. Hop is a specialty crop in Pacific Northwest states, where 99% of all U.S. hops are produced. To suppress T. urticae, growers often apply various acaricides. Unfortunately T. urticae has been documented to quickly develop resistance to these acaricides which directly cause control failures. Here, we investigated resistance ratios and distribution of multiple resistance-associated mutations in field collected T. urticae samples compared with a susceptible population. Our research revealed that a mutation in the cytochrome b gene (G126S) in 35% tested T. urticae populations and a mutation in the voltage-gated sodium channel gene (F1538I) in 66.7% populations may contribute resistance to bifenazate and bifenthrin, respectively. No mutations were detected in Glutamate-gated chloride channel subunits tested, suggesting target site insensitivity may not be important in our hop T. urticae resistance to abamectin. However, P450-mediated detoxification was observed and is a putative mechanism for abamectin resistance. Molecular mechanisms of T. urticae chemical adaptation in hopyards is imperative new information that will help growers develop effective and sustainable management strategies. PMID:26621458

  3. Molecular mechanisms of Tetranychus urticae chemical adaptation in hop fields.

    PubMed

    Piraneo, Tara G; Bull, Jon; Morales, Mariany A; Lavine, Laura C; Walsh, Douglas B; Zhu, Fang

    2015-01-01

    The two-spotted spider mite, Tetranychus urticae Koch is a major pest that feeds on >1,100 plant species. Many perennial crops including hop (Humulus lupulus) are routinely plagued by T. urticae infestations. Hop is a specialty crop in Pacific Northwest states, where 99% of all U.S. hops are produced. To suppress T. urticae, growers often apply various acaricides. Unfortunately T. urticae has been documented to quickly develop resistance to these acaricides which directly cause control failures. Here, we investigated resistance ratios and distribution of multiple resistance-associated mutations in field collected T. urticae samples compared with a susceptible population. Our research revealed that a mutation in the cytochrome b gene (G126S) in 35% tested T. urticae populations and a mutation in the voltage-gated sodium channel gene (F1538I) in 66.7% populations may contribute resistance to bifenazate and bifenthrin, respectively. No mutations were detected in Glutamate-gated chloride channel subunits tested, suggesting target site insensitivity may not be important in our hop T. urticae resistance to abamectin. However, P450-mediated detoxification was observed and is a putative mechanism for abamectin resistance. Molecular mechanisms of T. urticae chemical adaptation in hopyards is imperative new information that will help growers develop effective and sustainable management strategies. PMID:26621458

  4. [Insulin resistance as a mechanism of adaptation during human evolution].

    PubMed

    Ricart, W; Fernández-Real, J M

    2010-10-01

    The recent application of concepts of evolution to human disease is proving useful to understand certain pathophysiological mechanisms of different entities that span genomic alterations of immunity, respiratory and hormone function, and the circulatory and neural systems. However, effort has concentrated on explaining the keys to adaptation that define human metabolism and, since the early 1960s, several theories have been developed. This article reviews some of the hypotheses postulated in recent years on the potential benefit of insulin resistance and discusses the most recent knowledge. The concept of the thrifty gene seems to have been definitively refuted by current knowledge. The current paradigm describes an interaction between the metabolic and the immune systems resulting from their coevolution, promoted by evolutionary pressures triggered by fasting, infection and intake of different foods. The activation and regulation of these ancient mechanisms in integrated and interdependent areas defines insulin resistance as a survival strategy that is critical during fasting and in the fight against infection. The relationship with some components of the diet and, particularly, with the symbiotic intestinal microflora points to new paradigms in understanding the pathophysiology of obesity, metabolic syndrome and type 2 diabetes mellitus. PMID:20675202

  5. Mechanisms of adaptive evolution. Darwinism and Lamarckism restated.

    PubMed

    Aboitiz, F

    1992-07-01

    This article discusses the conceptual basis of the different mechanisms of adaptive evolution. It is argued that only two such mechanisms may conceivably exist, Lamarckism and Darwinism. Darwinism is the fundamental process generating the diversity of species. Some aspects of the gene-centered approach to Darwinism are questioned, since they do not account for the generation of biological diversity. Diversity in biological design must be explained in relation to the diversity of interactions of organisms (or other higher-level units) with their environment. This aspect is usually overlooked in gene-centered views of evolution. A variant of the gene-selectionist approach has been proposed to account for the spread of cultural traits in human societies. Alternatively, I argue that social evolution is rather driven by what I call pseudo-Lamarckian inheritance. Finally, I argue that Lamarckian and pseudo-Lamarckian inheritance are just special cases of faithful replication which are found in the development of some higher-order units, such as multicellular organisms and human societies.

  6. Physiologically responsive, mechanically adaptive polymer optical fibers for optogenetics.

    PubMed

    Jorfi, Mehdi; Voirin, Guy; Foster, E Johan; Weder, Christoph

    2014-05-15

    The capability to deliver light to specific locations within the brain using optogenetic tools has opened up new possibilities in the field of neural interfacing. In this context, optical fibers are commonly inserted into the brain to activate or mute neurons using photosensitive proteins. While chronic optogenetic stimulation studies are just beginning to emerge, knowledge gathered in connection with electrophysiological implants suggests that the mechanical mismatch of conventional optical fibers and the cortical tissue may be a significant contributor to neuroinflammatory response. Here, we present the design and fabrication of physiologically responsive, mechanically adaptive optical fibers made of poly(vinyl alcohol) (PVA) that may mitigate this problem. Produced by a one-step wet-spinning process, the fibers display a tensile storage modulus E' of ∼7000  MPa in the dry state at 25°C and can thus readily be inserted into cortical tissue. Exposure to water causes a drastic reduction of E' to ∼35  MPa on account of modest swelling with the water. The optical properties at 470 and 590 were comparable with losses of 0.7±0.04  dB/cm at 470 nm and 0.6±0.1  dB/cm at 590 nm in the dry state and 1.1±0.1  dB/cm at 470 nm and 0.9±0.3  dB/cm at 590 nm in the wet state. The dry end of a partially switched fiber with a length of 10 cm was coupled with a light-emitting diode with an output of 10.1 mW to deliver light with a power density of >500  mW/cm2 from the wet end, which is more than sufficient to stimulate neurons in vivo. Thus, even without a low-refractive index cladding, the physiologically responsive, mechanically adaptive optical fibers presented here appear to be a very useful new tool for future optogenetic studies.

  7. The use of the insanity defense as a jail diversion mechanism for mentally ill persons charged with misdemeanors.

    PubMed

    Schaefer, Michele N; Bloom, Joseph D

    2005-01-01

    Heightened awareness and concern regarding the large number of mentally ill misdemeanants in jails has led to a search for alternatives to jail and to the development nationwide of jail diversion programs for offenders with mental illness. Two such mechanisms-diversion to civil commitment and the use of mental health courts-are briefly reviewed. In Oregon, however, a rather unique mechanism is used to defer mentally ill misdemeanants (in addition to felons) from the criminal justice system: the insanity defense, with subsequent placement of the individual under Psychiatric Security Review Board jurisdiction. Statistics regarding such use from 1978 to 2001 are provided. The authors compare and contrast this jail alternative with both mental health courts and diversion to civil commitment, and discuss questions related to the feasibility of larger-scale use of this mechanism.

  8. Activation of defense mechanism in wheat by polyphenol oxidase from aphid saliva.

    PubMed

    Ma, Rui; Chen, Ju-Lian; Cheng, Deng-Fa; Sun, Jing-Rui

    2010-02-24

    The saliva of two cereal aphids, Sitobion avenae and Schizaphis graminum in third-instar nymphs, was collected after 24 h of feeding by 30 aphids, separately, on artificial diet sachets, and the salivary enzymes were determined. The result showed that polyphenol oxidase (PPO) existed in the saliva of both aphid species, and the enzymatic activities were 6.2 x 10(-3) U/g for S. avenae and 2.37 x 10(-1) U/g for S. graminum, revealing a 38-fold higher activity in the saliva of S. graminum than in the saliva of S. avenae. It was speculated that the higher PPO activity in S. graminum saliva was a contributing factor to the light yellow spot left on the feeding site of the wheat leaf by S. graminum; no such spot was left by S. avenae. After treatment of a wheat seedling with the saliva of S. avenae and S. graminum and PPO at the concentration of aphid saliva, transcript profiling data showed that aphid saliva and PPO significantly induced expression of the genes aos and fps. Because genes aos and fps encode the key enzymes in the defense signal pathways jasmonic acid and terpene signal pathways, respectively, it was deduced that PPO from aphid saliva, as the main elicitor, triggers an appropriate defense response in wheat through jasmonic acid and terpene signal pathways. PMID:20112908

  9. Pterostilbene Decreases the Antioxidant Defenses of Aggressive Cancer Cells In Vivo: A Physiological Glucocorticoids- and Nrf2-Dependent Mechanism

    PubMed Central

    Benlloch, María; Obrador, Elena; Valles, Soraya L.; Rodriguez, María L.; Sirerol, J. Antoni; Alcácer, Javier; Pellicer, José A.; Salvador, Rosario; Cerdá, Concha; Sáez, Guillermo T.

    2016-01-01

    Abstract Aims: Polyphenolic phytochemicals have anticancer properties. However, in mechanistic studies, lack of correlation with the bioavailable concentrations is a critical issue. Some reports had suggested that these molecules downregulate the stress response, which may affect growth and the antioxidant protection of malignant cells. Initially, we studied this potential underlying mechanism using different human melanomas (with genetic backgrounds correlating with most melanomas), growing in nude mice as xenografts, and pterostilbene (Pter, a natural dimethoxylated analog of resveratrol). Results: Intravenous administration of Pter decreased human melanoma growth in vivo. However, Pter, at levels measured within the tumors, did not affect melanoma growth in vitro. Pter inhibited pituitary production of the adrenocorticotropin hormone (ACTH), decreased plasma levels of corticosterone, and thereby downregulated the glucocorticoid receptor- and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent antioxidant defense system in growing melanomas. Exogenous corticosterone or genetically induced Nrf2 overexpression in melanoma cells prevented the inhibition of tumor growth and decreased antioxidant defenses in these malignant cells. These effects and mechanisms were also found in mice bearing different human pancreatic cancers. Glutathione depletion (selected as an antimelanoma strategy) facilitated the complete elimination by chemotherapy of melanoma cells isolated from mice treated with Pter. Innovation: Although bioavailability-related limitations may preclude direct anticancer effects in vivo, natural polyphenols may also interfere with the growth and defense of cancer cells by downregulating the pituitary gland-dependent ACTH synthesis. Conclusions: Pter downregulates glucocorticoid production, thus decreasing the glucocorticoid receptor and Nrf2-dependent signaling/transcription and the antioxidant protection of melanoma and pancreatic cancer cells

  10. Antimicrobial terpenes from oleoresin of ponderosa pine tree Pinus ponderosa: A defense mechanism against microbial invasion

    SciTech Connect

    Himejima, Masaki; Hobson, K.R.; Otsuka, Toshikazu; Wood, D.L.; Kubo, Isao )

    1992-10-01

    The oleoresin of the ponderosa pine, Pinus ponderosa (Pinaceae) exhibited broad antimicrobial activity. In order to identify the active compounds, the oleoresin was steam distilled to give a distillate and residue. The distillate contained mainly monoterpenes and some sesquiterpenes, while the residue consisted chiefly of four structurally related diterpene acids. An antimicrobial assay with the pure compounds indicated that the monoterpenes were active primarily against fungi, but there was also some activity against gram-positive bacteria. The diterpene acids, in contrast, only exhibited activity against gram-positive bacteria. Although not all of the identified sesquiterpenes could be tested, longifolene showed activity only against gram-positive bacteria. Therefore, it appears that the oleoresin of P. ponderosa functions as a biochemical defense against microbial invasion.

  11. Model Wheat Genotypes as Tools to Uncover Effective Defense Mechanisms Against the Hemibiotrophic Fungus Bipolaris sorokiniana.

    PubMed

    Ibeagha, Aloysius Ebelechukwu; Hückelhoven, Ralph; Schäfer, Patrick; Singh, Devendra Pal; Kogel, Karl-Heinz

    2005-05-01

    ABSTRACT We investigated the interaction of several differentially resistant wheatwith the hemibiotrophic phytopathogenic fungus Bipolaris sorokiniana (teleomorph Cochliobolus sativus). Wheat genotypes Yangmai, M 3 (W7976), Shanghai 4, and Chirya 7 showed higher levels of resistancewith cv. Sonalika, used as a susceptible control. In amicroscopic inspection, we found that fungal penetration intoepidermal layer failed mostly through a cell wall-associated defense. In cases where the fungus successfully overcame epidermal, its spread within the mesophyll tissue (necrotrophic phase) wasin the more resistant genotypes. Epidermal cell wall-associated, spreading as well as the extent of electrolyte leakage of infected, correlated well with field resistance. We propose that cellular hostsuch as formation of cell wall appositions as well as the degreeearly mesophyll spreading of fungal hyphae are indicative of thepotential of the respective host genotype and, therefore, could befor the characterization of new spot blotch resistance traits in cereals.

  12. Effects of provinol and its combinations with clinically used antiasthmatics on airway defense mechanisms in experimental allergic asthma.

    PubMed

    Kazimierová, I; Jošková, M; Pecháňová, O; Šutovská, M; Fraňová, S

    2015-01-01

    Our previous studies show that provinol, a polyphenolic compound, has anti-inflammatory activity during allergic inflammation. In the present study we investigated the effects of provinol and its combinations with clinically used antiasthmatics: budesonide or theophylline on airway defense mechanisms during experimental allergic asthma. Separate groups of guinea pigs were treated during the course of 21-day ovalbumin sensitization with provinol (20 mg/kg/day, p.o.), or budesonide (1 mM by inhalation), or theophylline (10 mg/kg/day, i.p.), and with a half-dose combination of provinol+budesonide or provinol+theophylline. Airways defense mechanisms: cough reflex and specific airway resistance (sRaw) were evaluated in vivo. Tracheal smooth muscle reactivity and mucociliary clearance were examined in vitro. The findings were that provinol caused significant decreases in sRaw and in tracheal smooth muscle contractility, a suppression of cough reflex, and positively modulated ciliary beat frequency. The bronchodilatory and antitussive effects of provinol were comparable with those of budesonide and theophylline. Provinol given as add-on treatment significantly potentiated the effects of budesonide or theophylline, although the doses of each were halved. We conclude that provinol not only has bronchodilatory and antitussive effects, but also potentiates similar effects exerted by budesonide and theophylline.

  13. Evidence that ferritin is UV inducible in human skin: part of a putative defense mechanism.

    PubMed

    Applegate, L A; Scaletta, C; Panizzon, R; Frenk, E

    1998-07-01

    As ferritin has been identified as an important factor in antioxidant defense in cultured human skin cells we evaluated the presence of ferritin in human skin in vivo and the modifications following irradiation with UVA I, UVA I + II, and solar simulating light by immunohistochemical analysis. We report that the putative protective protein ferritin is regularly present in the basal layer of unirradiated epidermis in vivo and that the induction of ferritin was dependent on wavelength and cell type. Following UVA I radiation, ferritin increased both in epidermal and in dermal tissue. The same response occurred, although to a lesser extent, with UVA I + II but did not occur following solar simulating radiation. Quantitative analysis for ferritin in cultured keratinocytes and fibroblasts from seven individuals following each UV spectra were also assessed by enzyme-linked immunosorbent assay. The induction of ferritin by UV was highly dependent on the waveband and cell type. UVA I and UVA I + II radiations induced ferritin expression in dermal fibroblasts up to 260% and 200% over basal levels, respectively. Solar simulating radiation produced only a small induction of approximately 130% over basal ferritin levels in dermal fibroblasts. Ferritin increased in cultured fibroblasts as early as 3 h post-UVA with a peak at 6 h that remained until 48 h; there was no observable qualitative or quantitative increase seen in the undifferentiated cultured epidermal keratinocytes. Our findings indicate that the putative defense system of ferritin exists in human skin in vivo and its induction is dependent on UV spectra and cell type. The increased concentrations of this antioxidant in human skin following acute UV radiation could afford increased protection against subsequent oxidative stress.

  14. Cl- uptake mechanism in freshwater-adapted tilapia (Oreochromis mossambicus).

    PubMed

    Chang, I-Chi; Hwang, Pung-Pung

    2004-01-01

    In this study, the correlation between Cl(-) influx in freshwater tilapia and various transporters or enzymes, the Cl(-)/HCO(3)(-) exchanger, Na(+),K(+)-ATPase, V-type H(+)-ATPase, and carbonic anhydrase were examined. The inhibitors 2x10(-4) M ouabain (a Na(+),K(+)-ATPase inhibitor), 10(-5) M NEM (a V-type H(+)-ATPase inhibitor), 10(-2) M ACTZ (acetazolamide, a carbonic anhydrase inhibitor), and 6x10(-4) M DIDS (a Cl(-)/HCO(3)(-) exchanger inhibitor) caused 40%, 60%-80%, 40%-60%, and 40%-60% reduction in Cl(-) influx of freshwater tilapia, respectively. The inhibitor 2x10(-4) M ouabain also caused 50%-65% inhibition in gill Na(+),K(+)-ATPase activity. Western blot results showed that protein levels of gill Na(+),K(+)-ATPase, V-type H(+)-ATPase, and carbonic anhydrase in tilapia acclimated in low-Cl(-) freshwater were significantly higher than those acclimated to high-Cl(-) freshwater. Based on these data, we conclude that Na(+),K(+)-ATPase, V-H(+)-ATPase, the Cl(-)/HCO(3)(-) exchanger, and carbonic anhydrase may be involved in the active Cl(-) uptake mechanism in gills of freshwater-adapted tilapia. PMID:15286914

  15. Skeletal adaptation to external loads optimizes mechanical properties: fact or fiction

    NASA Technical Reports Server (NTRS)

    Turner, R. T.

    2001-01-01

    The skeleton adapts to a changing mechanical environment but the widely held concept that bone cells are programmed to respond to local mechanical loads to produce an optimal mechanical structure is not consistent with the high frequency of bone fractures. Instead, the author suggests that other important functions of bone compete with mechanical adaptation to determine structure. As a consequence of competing demands, bone architecture never achieves an optimal mechanical structure. c2001 Lippincott Williams & Wilkins, Inc.

  16. Lifestyle and Host Defense Mechanisms of the Dung Beetle, Euoniticellus intermedius: The Toll Signaling Pathway

    PubMed Central

    Hull, Rodney; Alaouna, Mohamed; Khanyile, Lucky; Byrne, Marcus; Ntwasa, Monde

    2013-01-01

    The dung beetle, Euoniticellus intermedius (Reiche) (Coleoptera: Scarabaeidae) is an important ecological and agricultural agent. Their main activity, the burying of dung, improves quality of the soil and reduces pests that could cause illness in animals. E. intermedius are therefore important for agriculture and for good maintenance of the environment, and are regarded as effective biological control agents for parasites of the gastrointestinal tract in livestock. The ability of E. intermedius to co-exist comfortably with many microorganisms, some of which are important human pathogens, stimulated our interest in its host defense strategies. The aim of this study was to investigate the Toll signaling pathway, which is strongly activated by fungi. Gene expression associated with fungal infection was analyzed by using 2-D gel electrophoresis and mass spectroscopy. Furthermore, the partial adult transcriptome was investigated for the presence of known immune response genes by using high-throughput sequencing and bioinformatics. The results presented here suggest that E. intermedius responds to fungal challenge via the Toll signaling pathway. PMID:24735102

  17. Sulfur volatiles in guava (Psidium guajava L.) leaves: possible defense mechanism.

    PubMed

    Rouseff, Russell L; Onagbola, Ebenezer O; Smoot, John M; Stelinski, Lukasz L

    2008-10-01

    Volatiles from crushed and intact guava leaves (Psidium guajava L.) were collected using static headspace SPME and determined using GC-PFPD, pulsed flame photometric detection, and GC-MS. Leaf volatiles from four common citrus culitvars were examined similarly to determine the potential component(s) responsible for guava's protective effect against the Asian citrus psyllid (Diaphorina citri Kuwayama), which is the insect vector of Huanglongbing (HLB) or citrus greening disease. Seven sulfur volatiles were detected: hydrogen sulfide, sulfur dioxide, methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), methional, and dimethyl trisulfide (DMTS). Identifications were based on matching linear retention index values on ZB-5, DB-Wax, and PLOT columns and MS spectra in the case of DMDS and DMS. DMDS is an insect toxic, defensive volatile produced only by wounded guava but not citrus leaves and, thus, may be the component responsible for the protective effect of guava against the HLB vector. DMDS is formed immediately after crushing, becoming the major headspace volatile within 10 min. Forty-seven additional leaf volatiles were identified from LRI and MS data in the crushed guava leaf headspace.

  18. De novo Transcriptome Analysis Reveals Distinct Defense Mechanisms by Young and Mature Leaves of Hevea brasiliensis (Para Rubber Tree).

    PubMed

    Fang, Yongjun; Mei, Hailiang; Zhou, Binhui; Xiao, Xiaohu; Yang, Meng; Huang, Yacheng; Long, Xiangyu; Hu, Songnian; Tang, Chaorong

    2016-01-01

    Along with changes in morphology in the course of maturation, leaves of Hevea brasiliensis become more resistant to leaf diseases, including the South American Leaf Blight (SALB), a devastating fungal disease of this economically important tree species. To understand the underlying mechanisms of this defense, and to identify the candidate genes involved, we sequenced the Hevea leaf transcriptome at four developmental stages (I to IV) by Illumina sequencing. A total of 62.6 million high-quality reads were generated, and assembled into 98,796 unique transcripts. We identified 3,905 differentially expressed genes implicated in leaf development, 67.8% (2,651) of which were during the transition to leaf maturation. The genes involved in cyanogenic metabolism, lignin and anthocyanin biosynthesis were noteworthy for their distinct patterns of expression between developing leaves (stages I to III) and mature leaves (stage IV), and the correlation with the change in resistance to SALB and the Oidium/Colletotrichum leaf fall. The results provide a first profile of the molecular events that relate to the dynamics of leaf morphology and defense strategies during Hevea leaf development. This dataset is beneficial to devising strategies to engineer resistance to leaf diseases as well as other in-depth studies in Hevea tree. PMID:27619402

  19. De novo Transcriptome Analysis Reveals Distinct Defense Mechanisms by Young and Mature Leaves of Hevea brasiliensis (Para Rubber Tree)

    PubMed Central

    Fang, Yongjun; Mei, Hailiang; Zhou, Binhui; Xiao, Xiaohu; Yang, Meng; Huang, Yacheng; Long, Xiangyu; Hu, Songnian; Tang, Chaorong

    2016-01-01

    Along with changes in morphology in the course of maturation, leaves of Hevea brasiliensis become more resistant to leaf diseases, including the South American Leaf Blight (SALB), a devastating fungal disease of this economically important tree species. To understand the underlying mechanisms of this defense, and to identify the candidate genes involved, we sequenced the Hevea leaf transcriptome at four developmental stages (I to IV) by Illumina sequencing. A total of 62.6 million high-quality reads were generated, and assembled into 98,796 unique transcripts. We identified 3,905 differentially expressed genes implicated in leaf development, 67.8% (2,651) of which were during the transition to leaf maturation. The genes involved in cyanogenic metabolism, lignin and anthocyanin biosynthesis were noteworthy for their distinct patterns of expression between developing leaves (stages I to III) and mature leaves (stage IV), and the correlation with the change in resistance to SALB and the Oidium/Colletotrichum leaf fall. The results provide a first profile of the molecular events that relate to the dynamics of leaf morphology and defense strategies during Hevea leaf development. This dataset is beneficial to devising strategies to engineer resistance to leaf diseases as well as other in-depth studies in Hevea tree. PMID:27619402

  20. De novo Transcriptome Analysis Reveals Distinct Defense Mechanisms by Young and Mature Leaves of Hevea brasiliensis (Para Rubber Tree).

    PubMed

    Fang, Yongjun; Mei, Hailiang; Zhou, Binhui; Xiao, Xiaohu; Yang, Meng; Huang, Yacheng; Long, Xiangyu; Hu, Songnian; Tang, Chaorong

    2016-09-13

    Along with changes in morphology in the course of maturation, leaves of Hevea brasiliensis become more resistant to leaf diseases, including the South American Leaf Blight (SALB), a devastating fungal disease of this economically important tree species. To understand the underlying mechanisms of this defense, and to identify the candidate genes involved, we sequenced the Hevea leaf transcriptome at four developmental stages (I to IV) by Illumina sequencing. A total of 62.6 million high-quality reads were generated, and assembled into 98,796 unique transcripts. We identified 3,905 differentially expressed genes implicated in leaf development, 67.8% (2,651) of which were during the transition to leaf maturation. The genes involved in cyanogenic metabolism, lignin and anthocyanin biosynthesis were noteworthy for their distinct patterns of expression between developing leaves (stages I to III) and mature leaves (stage IV), and the correlation with the change in resistance to SALB and the Oidium/Colletotrichum leaf fall. The results provide a first profile of the molecular events that relate to the dynamics of leaf morphology and defense strategies during Hevea leaf development. This dataset is beneficial to devising strategies to engineer resistance to leaf diseases as well as other in-depth studies in Hevea tree.

  1. Repeated exposures to roadside particulate matter extracts suppresses pulmonary defense mechanisms, resulting in lipid and protein oxidative damage.

    PubMed

    Pardo, Michal; Porat, Ziv; Rudich, Assaf; Schauer, James J; Rudich, Yinon

    2016-03-01

    Exposure to particulate matter (PM) pollution in cities and urban canyons can be harmful to the exposed population. However, the underlying mechanisms that lead to health effects are not yet elucidated. It is postulated that exposure to repeated, small, environmentally relevant concentrations can affect lung homeostasis. This study examines the impact of repeated exposures to urban PM on mouse lungs with focus on inflammatory and oxidative stress parameters. Aqueous extracts from collected urban PM were administered to mice by 5 repeated intra-tracheal instillations (IT). Multiple exposures, led to an increase in cytokine levels in both bronchoalveolar lavage fluid and in the blood serum, indicating a systemic reaction. Lung mRNA levels of antioxidant/phase II detoxifying enzymes decreased by exposure to the PM extract, but not when metals were removed by chelation. Finally, disruption of lung tissue oxidant-inflammatory/defense balance was evidenced by increased levels of lipid and protein oxidation. Unlike response to a single IT exposure to the same dose and source of extract, multiple exposures result in lung oxidative damage and a systemic inflammatory reaction. These could be attributed to compromised capacity to activate the protective Nrf2 tissue defense system. It is suggested that water-soluble metals present in urban PM, potentially from break and tire wear, may constitute major drivers of the pulmonary and systemic responses to multiple exposure to urban PM.

  2. Neonatal host defense mechanisms against Listeria monocytogenes infection: the role of lipopolysaccharides and interferons.

    PubMed

    Bortolussi, R; Issekutz, T; Burbridge, S; Schellekens, H

    1989-03-01

    The human newborn infant is susceptible to lethal infection caused by a number of bacterial species including Listeria monocytogenes, a gram-positive rod which is pathogenic by virtue of its ability to survive intracellularly. In adult animals interferon (IFN)-alpha/beta and IFN-gamma or agents that induce or augment IFN production confer protection against lethal L. monocytogenes infection. Regulation and production of IFN is poorly understood during the neonatal period. We therefore evaluated the role of IFN-alpha/beta and IFN-gamma, IFN-inducers (polyinosinic:polycytidylic acid, amino-bromo-phenyl-pyrimidinone, amino-iodophenyl pyrimidinone) and lipopolysaccharide in modifying neonatal L. monocytogenes infection. Pretreatment of juvenile rats with polyinosinic:polycytidylic acid or lipopolysaccharide protected them against a lethal challenge with L. monocytogenes. Among newborn rats, polyinosinic:polycytidylic acid, amino-iodo-phenyl pyrimidinone and amino-bromophenyl-pyrimidinone gave significant protection, however, lipopolysaccharide did not influence survival. The role of IFN was further examined. Pretreatment of 3-d-old rats with purified IFN-alpha/beta, native rat IFN-gamma or rDNA rat IFN-gamma protected them against the lethality of subsequent L. monocytogenes injection. At 3 d after bacterial challenge, bacterial content in the spleens of 3-d-old rats pretreated with rIFN-gamma were significantly decreased compared to controls: IFN-alpha/beta-pretreated animals had less of a decrease, which become significant only 5 d after challenge. Our experiments indicate a role for IFN in neonatal host defense against L. monocytogenes infection.

  3. Flagellum-Mediated Biofilm Defense Mechanisms of Pseudomonas aeruginosa against Host-Derived Lactoferrin ▿

    PubMed Central

    Leid, Jeff G.; Kerr, Mathias; Selgado, Candice; Johnson, Chelsa; Moreno, Gabriel; Smith, Alyssa; Shirtliff, Mark E.; O'Toole, George A.; Cope, Emily K.

    2009-01-01

    Chronic infection with the gram-negative organism Pseudomonas aeruginosa is a leading cause of morbidity and mortality in human patients, despite high doses of antibiotics used to treat the various diseases this organism causes. These infections are chronic because P. aeruginosa readily forms biofilms, which are inherently resistant to antibiotics as well as the host's immune system. Our laboratory has been investigating specific mutations in P. aeruginosa that regulate biofilm bacterial susceptibility to the host. To continue our investigation of the role of genetics in bacterial biofilm host resistance, we examined P. aeruginosa biofilms that lack the flgK gene. This mutant lacks flagella, which results in defects in early biofilm development (up to 36 h). For these experiments, the flgK-disrupted strain and the parental strain (PA14) were used in a modified version of the 96-well plate microtiter assay. Biofilms were challenged with freshly isolated human leukocytes for 4 to 6 h and viable bacteria enumerated by CFU. Subsequent to the challenge, both mononuclear cells (monocytes and lymphocytes) and neutrophils, along with tumor necrosis factor alpha (TNF-α), were required for optimal killing of the flgK biofilm bacteria. We identified a cytokine cross talk network between mononuclear cells and neutrophils that was essential to the production of lactoferrin and bacterial killing. Our data suggest that TNF-α is secreted from mononuclear cells, causing neutrophil activation, resulting in the secretion of bactericidal concentrations of lactoferrin. These results extend previous studies of the importance of lactoferrin in the innate immune defense against bacterial biofilms. PMID:19651866

  4. Host defense mechanisms of human milk and their relations to enteric infections and necrotizing enterocolitis.

    PubMed

    Buescher, E S

    1994-06-01

    Human milk contains components that can mediate protection against symptomatic infection by means of classical and novel mechanisms. It has been demonstrated to protect infants against symptomatic infection by a variety of enteric pathogens. To date, mechanisms involving pathogen-specific sIgA are the best documented; however, roles for nonimmunoglobulin glycoconjugate and anti-inflammatory components may also exist. Based on both laboratory and clinical studies, human milk feeding appears to have protective effects against development of necrotizing enterocolitis.

  5. Chemical and Mechanical Defenses Vary among Maternal Lines and Leaf Ages in Verbascum thapsus L. (Scrophulariaceae) and Reduce Palatability to a Generalist Insect

    PubMed Central

    Alba, Christina; Bowers, M. Deane; Blumenthal, Dana; Hufbauer, Ruth A.

    2014-01-01

    Intra-specific variation in host-plant quality affects herbivore foraging decisions and, in turn, herbivore foraging decisions mediate plant fitness. In particular, variation in defenses against herbivores, both among and within plants, shapes herbivore behavior. If variation in defenses is genetically based, it can respond to natural selection by herbivores. We quantified intra-specific variation in iridoid glycosides, trichome length, and leaf strength in common mullein (Verbascum thapsus L, Scrophulariaceae) among maternal lines within a population and among leaves within plants, and related this variation to feeding preferences of a generalist herbivore, Trichopulsia ni Hübner. We found significant variation in all three defenses among maternal lines, with T. ni preferring plants with lower investment in chemical, but not mechanical, defense. Within plants, old leaves had lower levels of all defenses than young leaves, and were strongly preferred by T. ni. Caterpillars also preferred leaves with trichomes removed to leaves with trichomes intact. Differences among maternal lines indicate that phenotypic variation in defenses likely has a genetic basis. Furthermore, these results reveal that the feeding behaviors of T. ni map onto variation in plant defense in a predictable way. This work highlights the importance of variation in host-plant quality in driving interactions between plants and their herbivores. PMID:25127229

  6. Viewpoints: feeding mechanics, diet, and dietary adaptations in early hominins.

    PubMed

    Daegling, David J; Judex, Stefan; Ozcivici, Engin; Ravosa, Matthew J; Taylor, Andrea B; Grine, Frederick E; Teaford, Mark F; Ungar, Peter S

    2013-07-01

    Inference of feeding adaptation in extinct species is challenging, and reconstructions of the paleobiology of our ancestors have utilized an array of analytical approaches. Comparative anatomy and finite element analysis assist in bracketing the range of capabilities in taxa, while microwear and isotopic analyses give glimpses of individual behavior in the past. These myriad approaches have limitations, but each contributes incrementally toward the recognition of adaptation in the hominin fossil record. Microwear and stable isotope analysis together suggest that australopiths are not united by a single, increasingly specialized dietary adaptation. Their traditional (i.e., morphological) characterization as "nutcrackers" may only apply to a single taxon, Paranthropus robustus. These inferences can be rejected if interpretation of microwear and isotopic data can be shown to be misguided or altogether erroneous. Alternatively, if these sources of inference are valid, it merely indicates that there are phylogenetic and developmental constraints on morphology. Inherently, finite element analysis is limited in its ability to identify adaptation in paleobiological contexts. Its application to the hominin fossil record to date demonstrates only that under similar loading conditions, the form of the stress field in the australopith facial skeleton differs from that in living primates. This observation, by itself, does not reveal feeding adaptation. Ontogenetic studies indicate that functional and evolutionary adaptation need not be conceptually isolated phenomena. Such a perspective helps to inject consideration of mechanobiological principles of bone formation into paleontological inferences. Finite element analysis must employ such principles to become an effective research tool in this context. PMID:23794331

  7. Defense mechanisms and implicit emotion regulation: a comparison of a psychodynamic construct with one from contemporary neuroscience.

    PubMed

    Rice, Timothy R; Hoffman, Leon

    2014-08-01

    A growing interest in the neuroscience of emotion regulation, particularly the subfield of implicit emotion regulation, brings new opportunity for the psychodynamic treatment of neuropsychiatric disorders of childhood. At the same time, psychodynamic theorists have become more aware of the centrality of affects in mental life. This paper introduces a manualized psychodynamic approach called Regulation-Focused Dynamic Psychotherapy (RFP-C). Theoretically based on the domain construct of implicit emotion regulation (ER), this approach posits that contemporary affect-oriented conceptualizations of defense mechanisms are theoretically similar to the neuroscience construct of implicit emotion regulation. To illustrate this theoretical similarity, the literature connected with both concepts is reviewed. The implications of this idea, which could promote an interface between psychodynamics and contemporary academic psychiatry and psychology, are discussed.

  8. Priming for JA-dependent defenses using hexanoic acid is an effective mechanism to protect Arabidopsis against B. cinerea.

    PubMed

    Kravchuk, Zhana; Vicedo, Begonya; Flors, Víctor; Camañes, Gemma; González-Bosch, Carmen; García-Agustín, Pilar

    2011-03-01

    Soil drench treatments with hexanoic acid can effectively protect Arabidopsis plants against Botrytis cinerea through a mechanism based on a stronger and faster accumulation of JA-dependent defenses. Plants impaired in ethylene, salicylic acid, abscisic acid or glutathion pathways showed intact protection by hexanoic acid upon B. cinerea infection. Accordingly, no significant changes in the SA marker gene PR-1 in either the SA or ABA hormone balance were observed in the infected and treated plants. In contrast, the JA signaling pathway showed dramatic changes after hexanoic acid treatment, mainly when the pathogen was present. The impaired JA mutants, jin1-2 and jar1, were unable to display hexanoic acid priming against the necrotroph. In addition, hexanoic acid-treated plants infected with B. cinerea showed priming in the expression of the PDF1.2, PR-4 and VSP1 genes implicated in the JA pathways. Moreover, JA and OPDA levels were primed at early stages by hexanoic acid. Treatments also stimulated increased callose accumulation in response to the pathogen. Although callose accumulation has proved an effective IR mechanism against B. cinerea, it is apparently not essential to express hexanoic acid-induced resistance (HxAc-IR) because the mutant pmr4.1 (callose synthesis defective mutant) is protected by treatment. We recently described how hexanoic acid treatments can protect tomato plants against B. cinerea by stimulating ABA-dependent callose deposition and by priming OPDA and JA-Ile production. We clearly demonstrate here that Hx-IR is a dependent plant species, since this acid protects Arabidopsis plants against the same necrotroph by priming JA-dependent defenses without enhancing callose accumulation.

  9. First evidence for toxic defense based on the multixenobiotic resistance (MXR) mechanism in Daphnia magna.

    PubMed

    Campos, Bruno; Altenburger, Rolf; Gómez, Cristian; Lacorte, Silvia; Piña, Benjamin; Barata, Carlos; Luckenbach, Till

    2014-03-01

    The water flea Daphnia magna is widely used as test species in ecotoxicological bioassays. So far, there is no information available to which extent ATP binding cassette (ABC) transporter based multixenobiotic resistance (MXR) counteracts adverse chemical effects in this species. This, however, would be important for assessing to which extent the bio-active potential of a compound determined with this species depends on this cellular defense. We here present molecular, functional and toxicological studies that provide first evidence for ABC transporter-based MXR in D. magna. We cloned putatively MXR-related partial abcb1, abcc1/3, abcc4 and abcc5 coding sequences; respective transcripts were constitutively expressed in different D. magna life stages. MXR associated efflux activity was monitored in D. magna using the fluorescent substrate dyes rhodamine 123, rhodamine B and calcein-AM combined with inhibitors of human ABCB1 and/or ABCC transporter activities reversin 205, MK571 and cyclosporin A. With inhibitors present, efflux of dye substrates was reduced in D. magna in a concentration-dependent mode, as indicated by elevated accumulation of the dyes in D. magna tissues. In animals pre-exposed to mercury, pentachlorophenol or dacthal applied as inducers of ABC transporter expression, levels of some ABC transporter transcripts were increased in some cases showing that these genes can be chemically induced. Likewise, pre-exposure of animals to these chemicals decreased dye accumulation in tissue, indicating enhanced MXR transporter activity, likely associated with higher transporter protein levels. Toxicity assays with toxic transporter substrates mitoxantrone and chlorambucil that were applied singly and in combination with inhibitors were performed to study the tolerance role of Abcb1 and Abcc efflux transporters in D. magna. Joint toxicities of about half of the binary combinations of test compounds applied (substrate/inhibitor, substrate/substrate, inhibitor

  10. Mechanisms of motor adaptation in reactive balance control.

    PubMed

    Welch, Torrence D J; Ting, Lena H

    2014-01-01

    Balance control must be rapidly modified to provide stability in the face of environmental challenges. Although changes in reactive balance over repeated perturbations have been observed previously, only anticipatory postural adjustments preceding voluntary movements have been studied in the framework of motor adaptation and learning theory. Here, we hypothesized that adaptation occurs in task-level balance control during responses to perturbations due to central changes in the control of both anticipatory and reactive components of balance. Our adaptation paradigm consisted of a Training set of forward support-surface perturbations, a Reversal set of novel countermanding perturbations that reversed direction, and a Washout set identical to the Training set. Adaptation was characterized by a change in a motor variable from the beginning to the end of each set, the presence of aftereffects at the beginning of the Washout set when the novel perturbations were removed, and a return of the variable at the end of the Washout to a level comparable to the end of the Training set. Task-level balance performance was characterized by peak center of mass (CoM) excursion and velocity, which showed adaptive changes with repetitive trials. Only small changes in anticipatory postural control, characterized by body lean and background muscle activity were observed. Adaptation was found in the evoked long-latency muscular response, and also in the sensorimotor transformation mediating that response. Finally, in each set, temporal patterns of muscle activity converged towards an optimum predicted by a trade-off between maximizing motor performance and minimizing muscle activity. Our results suggest that adaptation in balance, as well as other motor tasks, is mediated by altering central sensitivity to perturbations and may be driven by energetic considerations. PMID:24810991

  11. Soluble Host Defense Lectins in Innate Immunity to Influenza Virus

    PubMed Central

    Ng, Wy Ching; Tate, Michelle D.; Brooks, Andrew G.; Reading, Patrick C.

    2012-01-01

    Host defenses against viral infections depend on a complex interplay of innate (nonspecific) and adaptive (specific) components. In the early stages of infection, innate mechanisms represent the main line of host defense, acting to limit the spread of virus in host tissues prior to the induction of the adaptive immune response. Serum and lung fluids contain a range of lectins capable of recognizing and destroying influenza A viruses (IAV). Herein, we review the mechanisms by which soluble endogenous lectins mediate anti-IAV activity, including their role in modulating IAV-induced inflammation and disease and their potential as prophylactic and/or therapeutic treatments during severe IAV-induced disease. PMID:22665991

  12. A review of adaptive mechanisms in cell responses towards oxidative stress caused by dental resin monomers.

    PubMed

    Krifka, Stephanie; Spagnuolo, Gianrico; Schmalz, Gottfried; Schweikl, Helmut

    2013-06-01

    Dental composite resins are biomaterials commonly used to aesthetically restore the structure and function of teeth impaired by caries, erosion, or fracture. Residual monomers released from resin restorations as a result of incomplete polymerization processes interact with living oral tissues. Monomers like triethylene glycol dimethacrylate (TEGDMA) or 2-hydroxylethyl methacrylate (HEMA) are cytotoxic via apoptosis, induce genotoxic effects, and delay the cell cycle. Monomers also influence the response of cells of the innate immune system, inhibit specific odontoblast cell functions, or delay the odontogenic differentiation and mineralization processes in pulp-derived cells including stem cells. These observations indicate that resin monomers act as environmental stressors which inevitably disturb regulatory cellular networks through interference with signal transduction pathways. We hypothesize that an understanding of the cellular mechanisms underlying these phenomena will provide a better estimation of the consequences associated with dental therapy using composite materials, and lead to innovative therapeutic strategies and improved materials being used at tissue interfaces within the oral cavity. Current findings strongly suggest that monomers enhance the formation of reactive oxygen species (ROS), which is most likely the cause of biological reactions activated by dental composites and resin monomers. The aim of the present review manuscript is to discuss adaptive cell responses to oxidative stress caused by monomers. The particular significance of a tightly controlled network of non-enzymatic as well as enzymatic antioxidants for the regulation of cellular redox homeostasis and antioxidant defense in monomer-exposed cells will be addressed. The expression of ROS-metabolizing antioxidant enzymes like superoxide dismutase (SOD1), glutathione peroxidase (GPx1/2), and catalase in cells exposed to monomers will be discussed with particular emphasis on the role

  13. A review of adaptive mechanisms in cell responses towards oxidative stress caused by dental resin monomers.

    PubMed

    Krifka, Stephanie; Spagnuolo, Gianrico; Schmalz, Gottfried; Schweikl, Helmut

    2013-06-01

    Dental composite resins are biomaterials commonly used to aesthetically restore the structure and function of teeth impaired by caries, erosion, or fracture. Residual monomers released from resin restorations as a result of incomplete polymerization processes interact with living oral tissues. Monomers like triethylene glycol dimethacrylate (TEGDMA) or 2-hydroxylethyl methacrylate (HEMA) are cytotoxic via apoptosis, induce genotoxic effects, and delay the cell cycle. Monomers also influence the response of cells of the innate immune system, inhibit specific odontoblast cell functions, or delay the odontogenic differentiation and mineralization processes in pulp-derived cells including stem cells. These observations indicate that resin monomers act as environmental stressors which inevitably disturb regulatory cellular networks through interference with signal transduction pathways. We hypothesize that an understanding of the cellular mechanisms underlying these phenomena will provide a better estimation of the consequences associated with dental therapy using composite materials, and lead to innovative therapeutic strategies and improved materials being used at tissue interfaces within the oral cavity. Current findings strongly suggest that monomers enhance the formation of reactive oxygen species (ROS), which is most likely the cause of biological reactions activated by dental composites and resin monomers. The aim of the present review manuscript is to discuss adaptive cell responses to oxidative stress caused by monomers. The particular significance of a tightly controlled network of non-enzymatic as well as enzymatic antioxidants for the regulation of cellular redox homeostasis and antioxidant defense in monomer-exposed cells will be addressed. The expression of ROS-metabolizing antioxidant enzymes like superoxide dismutase (SOD1), glutathione peroxidase (GPx1/2), and catalase in cells exposed to monomers will be discussed with particular emphasis on the role

  14. The brain--the organ of the psychic (the lesions/ the defense mechanisms).

    PubMed

    Rotarescu, Virginia; Ciurea, A V

    2010-01-01

    The article is based on the Leopold Szondi theory (March 11, 1893 - January 24, 1986), who was a Hungarian psychiatrist. He is known for the psychological tool that bears his name, the Szondi test. He developed a form of depth psychology that had some prominence in Europe in the mid-20th century, but has been ignored for the most part), the study seeks to correlate the szondian test results with the imagistic ones on a wide-range pathology. In the Neurosurgery Department, patients are investigated using modern exploration methods (MRI, CTscan, and computed EEG, etc.) in order to identify possible somatic lesions. The study's subjects selected during 2000-2004 from the patients admitted and investigated for neurosurgical conditions; they were divided into two subgroups, based on whether the organic lesions were or were not present (the independent variable). The exclusion criterion was a lesion due to external causes. Statistically meaningful there are seven types of Ego profiles, in relation with the lesion: the archaic ego [0 -], the inhibited ego [- +], the adaptive ego [- -], the narcissist ego [+ +], the identified ego [+/- 0], the fugitive ego [+/- -] and the possessed ego [0 +]. The nexus in the destiny's analysis description highlights the dialectic between the Ego's functions and the drived dangers when facing the demands of the concrete reality. PMID:20945811

  15. The brain–the organ of the psychic (The lesions / the defense mechanisms)

    PubMed Central

    Ciurea, AV

    2010-01-01

    The article is based on the Leopold Szondi theory (March 11, 1893 – January 24, 1986), who was a Hungarian psychiatrist. He is known for the psychological tool that bears his name, the Szondi test. He developed a form of depth psychology that had some prominence in Europe in the mid–20th century, but has been ignored for the most part), the study seeks to correlate the szondian test results with the imagistic ones on a wide–range pathology. In the Neurosurgery Department, patients are investigated using modern exploration methods (MRI, CTscan, and computed EEG, etc.) in order to identify possible somatic lesions. The study's subjects selected during 2000–2004 from the patients admitted and investigated for neurosurgical conditions; they were divided into two subgroups, based on whether the organic lesions were or were not present (the independent variable). The exclusion criterion was a lesion due to external causes. Statistically meaningful there are seven types of Ego profiles, in relation with the lesion: the archaic ego [0 –], the inhibited ego [– +], the adaptive ego [– –], the narcissist ego [+ +], the identified ego [+/– 0], the fugitive ego [+/– –] and the possessed ego [0 +]. The nexus in the destiny's analysis description highlights the dialectic between the Ego's functions and the drived dangers when facing the demands of the concrete reality. PMID:20945811

  16. Antioxidant defense mechanism in hydroponically grown Zea mays seedlings under moderate lead stress.

    PubMed

    Gupta, D K; Nicoloso, F T; Schetinger, M R C; Rossato, L V; Pereira, L B; Castro, G Y; Srivastava, S; Tripathi, R D

    2009-12-15

    The present study was designed to study the process of stress adaptation in roots and shoot of Zea mays seedlings grown under hydroponic conditions during exposure to lead (Pb) (0-200 microM) for 1-7 d. The alterations in growth and in the level of various biochemical parameters were accessed vis-à-vis Pb accumulation. The accumulation of Pb increased in a concentration-duration-dependent manner, however its translocation from root to shoot was low. At the same time, the level of malondialdehyde (MDA) increased with increasing Pb concentration. However, growth parameters, such as dry weight and root length did not show a significant decline to any of the Pb concentrations. In addition, the level of photosynthetic pigments decreased only upon exposure to high Pb concentrations. These results suggested an alleviation of the stress that was presumably being achieved by antioxidants viz., superoxide dismutase (SOD) and catalase (CAT) as well as ascorbic acid (AsA), which increased linearly with increasing Pb levels and exposure time. However, the level of non-protein thiols (NP-SH) in roots, in general, showed a decline beyond 4d that could be attributed to their consumption for the purpose of Pb detoxification. In conclusion, Zea mays can be used as an indicator species for Pb, and the various antioxidants might play a key role in the detoxification of Pb induced toxic effects.

  17. The brain--the organ of the psychic (the lesions/ the defense mechanisms).

    PubMed

    Rotarescu, Virginia; Ciurea, A V

    2010-01-01

    The article is based on the Leopold Szondi theory (March 11, 1893 - January 24, 1986), who was a Hungarian psychiatrist. He is known for the psychological tool that bears his name, the Szondi test. He developed a form of depth psychology that had some prominence in Europe in the mid-20th century, but has been ignored for the most part), the study seeks to correlate the szondian test results with the imagistic ones on a wide-range pathology. In the Neurosurgery Department, patients are investigated using modern exploration methods (MRI, CTscan, and computed EEG, etc.) in order to identify possible somatic lesions. The study's subjects selected during 2000-2004 from the patients admitted and investigated for neurosurgical conditions; they were divided into two subgroups, based on whether the organic lesions were or were not present (the independent variable). The exclusion criterion was a lesion due to external causes. Statistically meaningful there are seven types of Ego profiles, in relation with the lesion: the archaic ego [0 -], the inhibited ego [- +], the adaptive ego [- -], the narcissist ego [+ +], the identified ego [+/- 0], the fugitive ego [+/- -] and the possessed ego [0 +]. The nexus in the destiny's analysis description highlights the dialectic between the Ego's functions and the drived dangers when facing the demands of the concrete reality.

  18. Hepatitis C virus, mitochondria and auto/mitophagy: exploiting a host defense mechanism.

    PubMed

    Ruggieri, Vitalba; Mazzoccoli, Carmela; Pazienza, Valerio; Andriulli, Angelo; Capitanio, Nazzareno; Piccoli, Claudia

    2014-03-14

    Hepatitis C virus (HCV) is the major reason for liver transplantation and the main cause of liver-related morbidity and mortality in a great number of countries. As for the other viruses, this pathogen interferes in more than one process and in more than one way with host cell biology. A mounting body of evidence points, in particular, toward the drastic alterations of mitochondrial physiology and functions that virus is able to induce, albeit the mechanisms have partly remained elusive. Role of the mitochondria in immunity and in quality control systems, as autophagy, as well as the strategies that HCV has evolved to evade and even to manipulate mitochondrial surveillance for its benefit, highlights the importance of deepening the mechanisms that modulate this virus-mitochondrion interaction, not only to intensify our knowledge of the HCV infection pathogenesis but also to design efficient antiviral strategies.

  19. Crosstalk of Signaling Mechanisms Involved in Host Defense and Symbiosis Against Microorganisms in Rice.

    PubMed

    Akamatsu, Akira; Shimamoto, Ko; Kawano, Yoji

    2016-08-01

    Rice is one of the most important food crops, feeding about half population in the world. Rice pathogens cause enormous damage to rice production worldwide. In plant immunity research, considerable progress has recently been made in our understanding of the molecular mechanisms underlying microbe-associated molecular pattern (MAMP)-triggered immunity. Using genome sequencing and molecular techniques, a number of new MAMPs and their receptors have been identified in the past two decades. Notably, the mechanisms for chitin perception via the lysine motif (LysM) domain-containing receptor OsCERK1, as well as the mechanisms for bacterial MAMP (e.g. flg22, elf18) perception via the leucine-rich repeat (LRR) domain-containing receptors FLS2 and EFR, have been clarified in rice and Arabidopsis, respectively. In chitin signaling in rice, two direct substrates of OsCERK1, Rac/ROP GTPase guanine nucleotide exchange factor OsRacGEF1 and receptor-like cytoplasmic kinase OsRLCK185, have been identified as components of the OsCERK1 complex and are rapidly phosphorylated by OsCERK1 in response to chitin. Interestingly, OsCERK1 also participates in symbiosis with arbuscular mycorrhizal fungi (AMF) in rice and plays a role in the recognition of short-chitin molecules (CO4/5), which are symbiotic signatures included in AMF germinated spore exudates and induced by synthetic strigolactone. Thus, OsCERK1 contributes to both immunity and symbiotic responses. In this review, we describe recent studies on pathways involved in rice immunity and symbiotic signaling triggered by interactions with microorganisms. In addition, we describe recent advances in genetic engineering by using plant immune receptors and symbiotic microorganisms to enhance disease resistance of rice. PMID:27499679

  20. New host defense mechanisms against Candida species clarify the basis of clinical phenotypes.

    PubMed

    Hanna, Suheir; Etzioni, Amos; Etzoni, Amos

    2011-06-01

    Chronic Candida species infection of the skin and mucosal membranes is viewed as a group of disorders all sharing a similar clinical condition, the susceptibility to localized fungal infections, which can be isolated or as a feature associated with various other entities. Although the pathogenesis underlying such a tendency had previously been poorly understood, the last decade has witnessed significant progress in revealing the molecular and immunologic mechanisms involved in antifungal immunity. T(H)17 cells and their specific cytokines (IL-17A and IL-17F cytokines and IL-22) are the main players in conferring antifungal protection. Autoimmune polyendocrinopathy and ectodermal dystrophy and hyper-IgE syndrome are 2 entities caused by different genetic mutations affecting distinct immune pathways but eventually share a similar clinical phenotype of Candida species infection. Impaired T(H)17 responses, although mediated by different mechanisms, seem to underlie this common feature: neutralizing autoantibodies against IL-17A and 1L-22 are involved in patients with autoimmune polyendocrinopathy and ectodermal dystrophy syndrome, whereas abnormal T(H)17 proliferation and IL-17 production are observed in the latter. Although various degrees of T(H)17 dysfunction were also observed in most cases of isolated chronic mucocutaneous candidiasis, only in very few families was a distinct mutation detected (caspase recruitment domain family, member 9 [CARD9]), thus indicating certain forms of chronic mucocutaneous candidiasis as monogenic with a Mendelian pattern of inheritance. Hopefully, these data will open the way for further searches for other genes and for introducing new treatment modalities. PMID:21497889

  1. New host defense mechanisms against Candida species clarify the basis of clinical phenotypes.

    PubMed

    Hanna, Suheir; Etzioni, Amos; Etzoni, Amos

    2011-06-01

    Chronic Candida species infection of the skin and mucosal membranes is viewed as a group of disorders all sharing a similar clinical condition, the susceptibility to localized fungal infections, which can be isolated or as a feature associated with various other entities. Although the pathogenesis underlying such a tendency had previously been poorly understood, the last decade has witnessed significant progress in revealing the molecular and immunologic mechanisms involved in antifungal immunity. T(H)17 cells and their specific cytokines (IL-17A and IL-17F cytokines and IL-22) are the main players in conferring antifungal protection. Autoimmune polyendocrinopathy and ectodermal dystrophy and hyper-IgE syndrome are 2 entities caused by different genetic mutations affecting distinct immune pathways but eventually share a similar clinical phenotype of Candida species infection. Impaired T(H)17 responses, although mediated by different mechanisms, seem to underlie this common feature: neutralizing autoantibodies against IL-17A and 1L-22 are involved in patients with autoimmune polyendocrinopathy and ectodermal dystrophy syndrome, whereas abnormal T(H)17 proliferation and IL-17 production are observed in the latter. Although various degrees of T(H)17 dysfunction were also observed in most cases of isolated chronic mucocutaneous candidiasis, only in very few families was a distinct mutation detected (caspase recruitment domain family, member 9 [CARD9]), thus indicating certain forms of chronic mucocutaneous candidiasis as monogenic with a Mendelian pattern of inheritance. Hopefully, these data will open the way for further searches for other genes and for introducing new treatment modalities.

  2. Oxidative Damage and Cellular Defense Mechanisms in Sea Urchin Models of Aging

    PubMed Central

    Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

    2013-01-01

    The free radical or oxidative stress theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging due to the existence of species with tremendously different natural life spans including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate lifespan. Levels of protein carbonyls and 4-hydroxynonenal (HNE) measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age-pigment lipofuscin measured in muscle, nerve and esophagus, increased with age however it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species, however further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. PMID:23707327

  3. Application of an Improved Proteomics Method for Abundant Protein Cleanup: Molecular and Genomic Mechanisms Study in Plant Defense*

    PubMed Central

    Zhang, Yixiang; Gao, Peng; Xing, Zhuo; Jin, Shumei; Chen, Zhide; Liu, Lantao; Constantino, Nasie; Wang, Xinwang; Shi, Weibing; Yuan, Joshua S.; Dai, Susie Y.

    2013-01-01

    High abundance proteins like ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) impose a consistent challenge for the whole proteome characterization using shot-gun proteomics. To address this challenge, we developed and evaluated Polyethyleneimine Assisted Rubisco Cleanup (PARC) as a new method by combining both abundant protein removal and fractionation. The new approach was applied to a plant insect interaction study to validate the platform and investigate mechanisms for plant defense against herbivorous insects. Our results indicated that PARC can effectively remove Rubisco, improve the protein identification, and discover almost three times more differentially regulated proteins. The significantly enhanced shot-gun proteomics performance was translated into in-depth proteomic and molecular mechanisms for plant insect interaction, where carbon re-distribution was used to play an essential role. Moreover, the transcriptomic validation also confirmed the reliability of PARC analysis. Finally, functional studies were carried out for two differentially regulated genes as revealed by PARC analysis. Insect resistance was induced by over-expressing either jacalin-like or cupin-like genes in rice. The results further highlighted that PARC can serve as an effective strategy for proteomics analysis and gene discovery. PMID:23943779

  4. Coordinated Activation of Programmed Cell Death and Defense Mechanisms in Transgenic Tobacco Plants Expressing a Bacterial Proton Pump.

    PubMed Central

    Mittler, R.; Shulaev, V.; Lam, E.

    1995-01-01

    In plants, programmed cell death is thought to be activated during the hypersensitive response to certain avirulent pathogens and in the course of several differentiation processes. We describe a transgenic model system that mimics the activation of programmed cell death in higher plants. In this system, expression of a bacterial proton pump in transgenic tobacco plants activates a cell death pathway that may be similar to that triggered by recognition of an incompatible pathogen. Thus, spontaneous lesions that resemble hypersensitive response lesions are formed, multiple defense mechanisms are apparently activated, and systemic resistance is induced in the absence of a pathogen. Interestingly, mutation of a single amino acid in the putative channel of this proton pump renders it inactive with respect to lesion formation and induction of resistance to pathogen challenge. This transgenic model system may provide insights into the mechanisms involved in mediating cell death in higher plants. In addition, it may also be used as a general agronomic tool to enhance disease protection. PMID:12242350

  5. Application of an improved proteomics method for abundant protein cleanup: molecular and genomic mechanisms study in plant defense.

    PubMed

    Zhang, Yixiang; Gao, Peng; Xing, Zhuo; Jin, Shumei; Chen, Zhide; Liu, Lantao; Constantino, Nasie; Wang, Xinwang; Shi, Weibing; Yuan, Joshua S; Dai, Susie Y

    2013-11-01

    High abundance proteins like ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) impose a consistent challenge for the whole proteome characterization using shot-gun proteomics. To address this challenge, we developed and evaluated Polyethyleneimine Assisted Rubisco Cleanup (PARC) as a new method by combining both abundant protein removal and fractionation. The new approach was applied to a plant insect interaction study to validate the platform and investigate mechanisms for plant defense against herbivorous insects. Our results indicated that PARC can effectively remove Rubisco, improve the protein identification, and discover almost three times more differentially regulated proteins. The significantly enhanced shot-gun proteomics performance was translated into in-depth proteomic and molecular mechanisms for plant insect interaction, where carbon re-distribution was used to play an essential role. Moreover, the transcriptomic validation also confirmed the reliability of PARC analysis. Finally, functional studies were carried out for two differentially regulated genes as revealed by PARC analysis. Insect resistance was induced by over-expressing either jacalin-like or cupin-like genes in rice. The results further highlighted that PARC can serve as an effective strategy for proteomics analysis and gene discovery.

  6. Overlapping and complementary oxidative stress defense mechanisms in nontypeable Haemophilus influenzae.

    PubMed

    Harrison, Alistair; Baker, Beth D; Munson, Robert S

    2015-01-01

    The Gram-negative commensal bacterium nontypeable Haemophilus influenzae (NTHI) can cause respiratory tract diseases that include otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During colonization and infection, NTHI withstands oxidative stress generated by reactive oxygen species produced endogenously, by the host, and by other copathogens and flora. These reactive oxygen species include superoxide, hydrogen peroxide (H2O2), and hydroxyl radicals, whose killing is amplified by iron via the Fenton reaction. We previously identified genes that encode proteins with putative roles in protection of the NTHI isolate strain 86-028NP against oxidative stress. These include catalase (HktE), peroxiredoxin/glutaredoxin (PgdX), and a ferritin-like protein (Dps). Strains were generated with mutations in hktE, pgdX, and dps. The hktE mutant and a pgdX hktE double mutant were more sensitive than the parent to killing by H2O2. Conversely, the pgdX mutant was more resistant to H2O2 due to increased catalase activity. Supporting the role of killing via the Fenton reaction, binding of iron by Dps significantly mitigated the effect of H2O2-mediated killing. NTHI thus utilizes several effectors to resist oxidative stress, and regulation of free iron is critical to this protection. These mechanisms will be important for successful colonization and infection by this opportunistic human pathogen. PMID:25368297

  7. Overlapping and complementary oxidative stress defense mechanisms in nontypeable Haemophilus influenzae.

    PubMed

    Harrison, Alistair; Baker, Beth D; Munson, Robert S

    2015-01-01

    The Gram-negative commensal bacterium nontypeable Haemophilus influenzae (NTHI) can cause respiratory tract diseases that include otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During colonization and infection, NTHI withstands oxidative stress generated by reactive oxygen species produced endogenously, by the host, and by other copathogens and flora. These reactive oxygen species include superoxide, hydrogen peroxide (H2O2), and hydroxyl radicals, whose killing is amplified by iron via the Fenton reaction. We previously identified genes that encode proteins with putative roles in protection of the NTHI isolate strain 86-028NP against oxidative stress. These include catalase (HktE), peroxiredoxin/glutaredoxin (PgdX), and a ferritin-like protein (Dps). Strains were generated with mutations in hktE, pgdX, and dps. The hktE mutant and a pgdX hktE double mutant were more sensitive than the parent to killing by H2O2. Conversely, the pgdX mutant was more resistant to H2O2 due to increased catalase activity. Supporting the role of killing via the Fenton reaction, binding of iron by Dps significantly mitigated the effect of H2O2-mediated killing. NTHI thus utilizes several effectors to resist oxidative stress, and regulation of free iron is critical to this protection. These mechanisms will be important for successful colonization and infection by this opportunistic human pathogen.

  8. The antiviral defense mechanisms in mandarin fish induced by DNA vaccination against a rhabdovirus.

    PubMed

    Chen, Zhong-Yuan; Lei, Xiao-Ying; Zhang, Qi-Ya

    2012-06-15

    Plasmid DNAs containing Siniperca chuatsi rhabdovirus (SCRV) glycoprotein gene (pcDNA-G) and nucleoprotein gene (pcDNA-N) were constructed, and used to determine the antiviral immune response elicited by DNA vaccination in mandarin fish. In vitro and in vivo expression of the plasmid constructs was confirmed in transfected cells and muscle tissues of vaccinated fish by Western blot, indirect immunofluorescence or RT-PCR analysis. Fish injected with pcDNA-G exhibited protective effect against SCRV challenge with a relative percent survival (RPS) of 77.5%, but no significant protection (RPS of 2.5%) was observed in fish vaccinated with pcDNA-N. Immunohistochemical analysis showed that vaccination with pcDNA-G decreased histological lesions and suppressed the virus replication in fish target organs, e.g. kidney, liver, spleen, gill and heart. Transcriptional analysis further revealed that the expression levels of type I IFN system genes including interferon regulation factor-7 (IRF-7) gene, myxovirus resistance (Mx) gene and virus inhibitory protein (Viperin) gene were strongly up-regulated after injection with pcDNA-G, whereas the level of transcription of immunoglobulin M (IgM) gene did not show a statistically significant change. These results reveal that type I IFN antiviral immune response is rapidly triggered by the plasmid DNA containing rhabdovirus glycoprotein gene in fish, which offers an explanation of molecular mechanisms for DNA vaccination inducing mandarin fish resist to SCRV disease.

  9. Adaptive camouflage in the VIS and IR spectral range: main principles and mechanisms

    NASA Astrophysics Data System (ADS)

    Schwarz, Alexander

    2015-10-01

    This paper presents a survey of main applicable technical principles and mechanisms for adaptive camouflage in the visible (VIS) and infrared (IR) spectral ranges. All principles are described by their operation method and technical data such as the active spectral range, the degree and speed of adaptation, weight, power consumption, robustness, usability, lifetime, technology readiness level (TRL) etc.. The paper allows to compare the different principles and to assess them with regard to an application to an adaptive camouflage system.

  10. Lead tolerance mechanism in Conyza canadensis: subcellular distribution, ultrastructure, antioxidative defense system, and phytochelatins.

    PubMed

    Li, Ying; Zhou, Chuifan; Huang, Meiying; Luo, Jiewen; Hou, Xiaolong; Wu, Pengfei; Ma, Xiangqing

    2016-03-01

    We used hydroponic experiments to examine the effects of different concentrations of lead (Pb) on the performance of the Pb-tolerable plant Conyza canadensis. In these experiments, most of the Pb was accumulated in the roots; there was very little Pb accumulated in stems and leaves. C. canadensis is able to take up significant amounts of Pb whilst greatly restricting its transportation to specific parts of the aboveground biomass. High Pb concentrations inhibited plant growth, increased membrane permeability, elevated antioxidant enzyme activity in roots, and caused a significant increase in root H2O2 and malondialdehyde content. Analysis of Pb content at the subcellular level showed that most Pb was associated with the cell wall fraction, followed by the nucleus-rich fraction, and with a minority present in the mitochondrial and soluble fractions. Furthermore, transmission electron microscopy and energy dispersive X-ray analysis of root cells revealed that the cell wall and intercellular space in C. canadensis roots are the main locations of Pb accumulation. Additionally, high Pb concentrations adversely affected the cellular structure of C. canadensis roots. The increased enzyme activity suggests that the antioxidant system may play an important role in eliminating or alleviating Pb toxicity in C. canadensis roots. However, the levels of non-protein sulfhydryl compounds, glutathione, and phytochelatin did not significantly change in either the roots or leaves under Pb-contaminated treatments. Our results provide strong evidence that cell walls restrict Pb uptake into the root and act as an important barrier protecting root cells, while demonstrating that antioxidant enzyme levels are correlated with Pb exposure. These findings demonstrate the roles played by these detoxification mechanisms in supporting Pb tolerance in C. canadensis. PMID:26733305

  11. Immune-related transcriptome of Coptotermes formosanus Shiraki workers: the defense mechanism.

    PubMed

    Hussain, Abid; Li, Yi-Feng; Cheng, Yu; Liu, Yang; Chen, Chuan-Cheng; Wen, Shuo-Yang

    2013-01-01

    Formosan subterranean termites, Coptotermes formosanus Shiraki, live socially in microbial-rich habitats. To understand the molecular mechanism by which termites combat pathogenic microbes, a full-length normalized cDNA library and four Suppression Subtractive Hybridization (SSH) libraries were constructed from termite workers infected with entomopathogenic fungi (Metarhizium anisopliae and Beauveria bassiana), Gram-positive Bacillus thuringiensis and Gram-negative Escherichia coli, and the libraries were analyzed. From the high quality normalized cDNA library, 439 immune-related sequences were identified. These sequences were categorized as pattern recognition receptors (47 sequences), signal modulators (52 sequences), signal transducers (137 sequences), effectors (39 sequences) and others (164 sequences). From the SSH libraries, 27, 17, 22 and 15 immune-related genes were identified from each SSH library treated with M. anisopliae, B. bassiana, B. thuringiensis and E. coli, respectively. When the normalized cDNA library was compared with the SSH libraries, 37 immune-related clusters were found in common; 56 clusters were identified in the SSH libraries, and 259 were identified in the normalized cDNA library. The immune-related gene expression pattern was further investigated using quantitative real time PCR (qPCR). Important immune-related genes were characterized, and their potential functions were discussed based on the integrated analysis of the results. We suggest that normalized cDNA and SSH libraries enable us to discover functional genes transcriptome. The results remarkably expand our knowledge about immune-inducible genes in C. formosanus Shiraki and enable the future development of novel control strategies for the management of Formosan subterranean termites.

  12. Immune-Related Transcriptome of Coptotermes formosanus Shiraki Workers: The Defense Mechanism

    PubMed Central

    Hussain, Abid; Li, Yi-Feng; Cheng, Yu; Liu, Yang; Chen, Chuan-Cheng; Wen, Shuo-Yang

    2013-01-01

    Formosan subterranean termites, Coptotermes formosanus Shiraki, live socially in microbial-rich habitats. To understand the molecular mechanism by which termites combat pathogenic microbes, a full-length normalized cDNA library and four Suppression Subtractive Hybridization (SSH) libraries were constructed from termite workers infected with entomopathogenic fungi (Metarhizium anisopliae and Beauveria bassiana), Gram-positive Bacillus thuringiensis and Gram-negative Escherichia coli, and the libraries were analyzed. From the high quality normalized cDNA library, 439 immune-related sequences were identified. These sequences were categorized as pattern recognition receptors (47 sequences), signal modulators (52 sequences), signal transducers (137 sequences), effectors (39 sequences) and others (164 sequences). From the SSH libraries, 27, 17, 22 and 15 immune-related genes were identified from each SSH library treated with M. anisopliae, B. bassiana, B. thuringiensis and E. coli, respectively. When the normalized cDNA library was compared with the SSH libraries, 37 immune-related clusters were found in common; 56 clusters were identified in the SSH libraries, and 259 were identified in the normalized cDNA library. The immune-related gene expression pattern was further investigated using quantitative real time PCR (qPCR). Important immune-related genes were characterized, and their potential functions were discussed based on the integrated analysis of the results. We suggest that normalized cDNA and SSH libraries enable us to discover functional genes transcriptome. The results remarkably expand our knowledge about immune-inducible genes in C. formosanus Shiraki and enable the future development of novel control strategies for the management of Formosan subterranean termites. PMID:23874972

  13. Lead tolerance mechanism in Conyza canadensis: subcellular distribution, ultrastructure, antioxidative defense system, and phytochelatins.

    PubMed

    Li, Ying; Zhou, Chuifan; Huang, Meiying; Luo, Jiewen; Hou, Xiaolong; Wu, Pengfei; Ma, Xiangqing

    2016-03-01

    We used hydroponic experiments to examine the effects of different concentrations of lead (Pb) on the performance of the Pb-tolerable plant Conyza canadensis. In these experiments, most of the Pb was accumulated in the roots; there was very little Pb accumulated in stems and leaves. C. canadensis is able to take up significant amounts of Pb whilst greatly restricting its transportation to specific parts of the aboveground biomass. High Pb concentrations inhibited plant growth, increased membrane permeability, elevated antioxidant enzyme activity in roots, and caused a significant increase in root H2O2 and malondialdehyde content. Analysis of Pb content at the subcellular level showed that most Pb was associated with the cell wall fraction, followed by the nucleus-rich fraction, and with a minority present in the mitochondrial and soluble fractions. Furthermore, transmission electron microscopy and energy dispersive X-ray analysis of root cells revealed that the cell wall and intercellular space in C. canadensis roots are the main locations of Pb accumulation. Additionally, high Pb concentrations adversely affected the cellular structure of C. canadensis roots. The increased enzyme activity suggests that the antioxidant system may play an important role in eliminating or alleviating Pb toxicity in C. canadensis roots. However, the levels of non-protein sulfhydryl compounds, glutathione, and phytochelatin did not significantly change in either the roots or leaves under Pb-contaminated treatments. Our results provide strong evidence that cell walls restrict Pb uptake into the root and act as an important barrier protecting root cells, while demonstrating that antioxidant enzyme levels are correlated with Pb exposure. These findings demonstrate the roles played by these detoxification mechanisms in supporting Pb tolerance in C. canadensis.

  14. How Lower- and Working-Class Youth Become Middle-Class Adults: The Association between Ego Defense Mechanisms and Upward Social Mobility.

    ERIC Educational Resources Information Center

    Snarey, John R.; Vaillant, George E.

    1985-01-01

    Among 278 inner-city men studied for four decades and over three generations, eight variables captured 28 percent of the explained variance in upward social mobility: IQ, mother's education, mother's occupation, boyhood ego strength, and four ego defense mechanisms--intellectualization, dissociation, sublimation, and anticipation.…

  15. Adaptive finite element methods for two-dimensional problems in computational fracture mechanics

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Bass, J. M.; Spradley, L. W.

    1994-01-01

    Some recent results obtained using solution-adaptive finite element methods in two-dimensional problems in linear elastic fracture mechanics are presented. The focus is on the basic issue of adaptive finite element methods for validating the new methodology by computing demonstration problems and comparing the stress intensity factors to analytical results.

  16. Low-dose AgNPs reduce lung mechanical function and innate immune defense in the absence of cellular toxicity

    PubMed Central

    Botelho, Danielle J.; Leo, Bey Fen; Massa, Christopher B.; Sarkar, Srijata; Tetley, Terry D.; Chung, Kian Fan; Chen, Shu; Ryan, Mary P.; Porter, Alexandra E.; Zhang, Junfeng; Schwander, Stephan K.; Gow, Andrew J.

    2016-01-01

    Multiple studies have examined the direct cellular toxicity of silver nanoparticles (AgNPs). However, the lung is a complex biological system with multiple cell types and a lipid-rich surface fluid; therefore, organ level responses may not depend on direct cellular toxicity. We hypothesized that interaction with the lung lining is a critical determinant of organ level responses. Here, we have examined the effects of low dose intratracheal instillation of AgNPs (0.05 µg/g body weight) 20 and 110nm diameter in size, and functionalized with citrate or polyvinylpyrrolidone. Both size and functionalization were significant factors in particle aggregation and lipid interaction in vitro. One day post-intratracheal instillation lung function was assessed, and bronchoalveolar lavage (BAL) and lung tissue collected. There were no signs of overt inflammation. There was no change in surfactant protein-B content in the BAL but there was loss of surfactant protein-D with polyvinylpyrrolidone (PVP)-stabilized particles. Mechanical impedance data demonstrated a significant increase in pulmonary elastance as compared to control, greatest with 110nm PVP-stabilized particles. Seven days post-instillation of PVP-stabilized particles increased BAL cell counts, and reduced lung function was observed. These changes resolved by 21 days. Hence, AgNP-mediated alterations in the lung lining and mechanical function resolve by 21 days. Larger particles and PVP stabilization produce the largest disruptions. These studies demonstrate that low dose AgNPs elicit deficits in both mechanical and innate immune defense function, suggesting that organ level toxicity should be considered. PMID:26152688

  17. Low-dose AgNPs reduce lung mechanical function and innate immune defense in the absence of cellular toxicity.

    PubMed

    Botelho, Danielle J; Leo, Bey Fen; Massa, Christopher B; Sarkar, Srijata; Tetley, Terry D; Chung, Kian Fan; Chen, Shu; Ryan, Mary P; Porter, Alexandra E; Zhang, Junfeng; Schwander, Stephan K; Gow, Andrew J

    2016-01-01

    Multiple studies have examined the direct cellular toxicity of silver nanoparticles (AgNPs). However, the lung is a complex biological system with multiple cell types and a lipid-rich surface fluid; therefore, organ level responses may not depend on direct cellular toxicity. We hypothesized that interaction with the lung lining is a critical determinant of organ level responses. Here, we have examined the effects of low dose intratracheal instillation of AgNPs (0.05 μg/g body weight) 20 and 110 nm diameter in size, and functionalized with citrate or polyvinylpyrrolidone. Both size and functionalization were significant factors in particle aggregation and lipid interaction in vitro. One day post-intratracheal instillation lung function was assessed, and bronchoalveolar lavage (BAL) and lung tissue collected. There were no signs of overt inflammation. There was no change in surfactant protein-B content in the BAL but there was loss of surfactant protein-D with polyvinylpyrrolidone (PVP)-stabilized particles. Mechanical impedance data demonstrated a significant increase in pulmonary elastance as compared to control, greatest with 110 nm PVP-stabilized particles. Seven days post-instillation of PVP-stabilized particles increased BAL cell counts, and reduced lung function was observed. These changes resolved by 21 days. Hence, AgNP-mediated alterations in the lung lining and mechanical function resolve by 21 days. Larger particles and PVP stabilization produce the largest disruptions. These studies demonstrate that low dose AgNPs elicit deficits in both mechanical and innate immune defense function, suggesting that organ level toxicity should be considered.

  18. Root developmental adaptation to Fe toxicity: Mechanisms and management.

    PubMed

    Li, Guangjie; Kronzucker, Herbert J; Shi, Weiming

    2016-01-01

    Iron (Fe) is an essential microelement but is highly toxic when in excess. To cope with Fe excess, plants have evolved complex adaptive responses that include morphological and physiological modifications. The highly dynamic adjustments in overall root system architecture (RSA) determine root plasticity and allow plants to efficiently adapt to environmental constraints. However, the effects of Fe excess on RSA are poorly understood. Recently, we showed that excess Fe treatment in Arabidopsis not only directly impairs primary root (PR) growth but also arrests lateral root (LR) formation by acting at the tip of the growing primary root. Such a change is believed to help RSA adjust and restrict excessive Fe absorption in the part of the rhizosphere subject to acute toxicity while maintaining the absorption of other nutrients in the less stressed components of the root system. We further showed that the suppression of PR growth and LR formation under excess Fe is alleviated by K(+) addition, providing useful insight into the effectiveness of nutrient management to improve RSA and alleviate Fe toxicity symptoms in the field.

  19. Mechanisms of Cardiopulmonary Adaptation to Microgravity. Part 2

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Session TP1 contains short reports concerning: (1) Autonomic Regulation of Circulation and Mechanical Function of Heart at Different Stages of 14th Month Space Flight; (2) Cardiovascular Oxygen Transport in Exercising Humans in Microgravity; (3) Venous Hemodynamic Changes Assessed by Air Plethysmography During a 16-Day Space Flight; (4) Respiratory Mechanics After 180 Days Space Mission (EUROMIR'95); (5) Assessment of the Sympathetic and the Parasympathetic Nervous Activity During Parabolic Flight by Pupillary Light Reflex; and(6) Vascular Response to Different Gravity.

  20. Characterization of Hg-phytochelatins complexes in vines (Vitis vinifera cv Malbec) as defense mechanism against metal stress.

    PubMed

    Spisso, Adrian A; Cerutti, Soledad; Silva, Fernanda; Pacheco, Pablo H; Martinez, Luis D

    2014-06-01

    An approach to understand vines (Vitis vinifera) defense mechanism against heavy metal stress by isolation and determination of Hg-phytochelatins (PCs) complexes was performed. PCs are important molecules involved in the control of metal concentration in plants. PCs complex toxic metals through -SH groups and stores them inside cells vacuole avoiding any toxic effect of free metals in the cytosol. The Hg-PCs identification was achieved by determination of Hg and S as hetero-tagged atoms. A method involving two-dimensional chromatographic analysis coupled to atomic spectrometry and confirmation by tandem mass spectrometry is proposed. An approach involving size exclusion chromatography coupled to inductively coupled plasma mass spectrometry on roots, stems, and leaves extracts describing Hg distribution according to molecular weight and sulfur associations is proposed for the first time. Medium-low molecular weight Hg-S associations of 29-100 kDa were found, suggesting PCs presence. A second approach employing reversed-phase chromatography coupled to atomic fluorescence spectrometry analysis allowed the determination of Hg-PCs complexes within the mentioned fractions. Chromatograms showed Hg-PC2, Hg-PC3 and Hg-PC4 presence only in roots. Hg-PCs presence in roots was confirmed by ESI-MS/MS analysis. PMID:24715273

  1. Effect of Calendula officinalis Flower Extract on Acute Phase Proteins, Antioxidant Defense Mechanism and Granuloma Formation During Thermal Burns.

    PubMed

    Chandran, Preethi K; Kuttan, Ramadasan

    2008-09-01

    Effect of Calendula officinalis flower extract was investigated against experimentally induced thermal burns in rats. Burn injury was made on the shaven back of the rats under anesthesia and the animals were treated orally with different doses of the flower extract (20 mg, 100 mg and 200 mg/kg body weight). The animals treated with the extract showed significant improvement in healing when compared with the control untreated animals. The indicators of the wound healing such as collagen-hydroxyproline and hexosamine contents were significantly increased in the treated group indicating accelerated wound healing in the treated animals. The acute phase proteins-haptoglobin and orosomucoid which were increased due to burn injury were found to be decreased significantly in 200 mg/kg body weight extract treated animals. The antioxidant defense mechanism, which was decreased in the liver during burn injury, was found to be enhanced in treated animals. The lipid peroxidation was significantly lowered in the treated group when compared to control animals. Tissue damage marker enzymes- alkaline phosphatase, alanine and aspartate transaminases were significantly lowered in the treated groups in a dose dependant manner. The histopathological analyses of skin tissue also give the evidence of the increased healing potential of the extract after burn injury.

  2. Characterization of Hg-phytochelatins complexes in vines (Vitis vinifera cv Malbec) as defense mechanism against metal stress.

    PubMed

    Spisso, Adrian A; Cerutti, Soledad; Silva, Fernanda; Pacheco, Pablo H; Martinez, Luis D

    2014-06-01

    An approach to understand vines (Vitis vinifera) defense mechanism against heavy metal stress by isolation and determination of Hg-phytochelatins (PCs) complexes was performed. PCs are important molecules involved in the control of metal concentration in plants. PCs complex toxic metals through -SH groups and stores them inside cells vacuole avoiding any toxic effect of free metals in the cytosol. The Hg-PCs identification was achieved by determination of Hg and S as hetero-tagged atoms. A method involving two-dimensional chromatographic analysis coupled to atomic spectrometry and confirmation by tandem mass spectrometry is proposed. An approach involving size exclusion chromatography coupled to inductively coupled plasma mass spectrometry on roots, stems, and leaves extracts describing Hg distribution according to molecular weight and sulfur associations is proposed for the first time. Medium-low molecular weight Hg-S associations of 29-100 kDa were found, suggesting PCs presence. A second approach employing reversed-phase chromatography coupled to atomic fluorescence spectrometry analysis allowed the determination of Hg-PCs complexes within the mentioned fractions. Chromatograms showed Hg-PC2, Hg-PC3 and Hg-PC4 presence only in roots. Hg-PCs presence in roots was confirmed by ESI-MS/MS analysis.

  3. Effect of Calendula officinalis Flower Extract on Acute Phase Proteins, Antioxidant Defense Mechanism and Granuloma Formation During Thermal Burns

    PubMed Central

    Chandran, Preethi K.; Kuttan, Ramadasan

    2008-01-01

    Effect of Calendula officinalis flower extract was investigated against experimentally induced thermal burns in rats. Burn injury was made on the shaven back of the rats under anesthesia and the animals were treated orally with different doses of the flower extract (20 mg, 100 mg and 200 mg/kg body weight). The animals treated with the extract showed significant improvement in healing when compared with the control untreated animals. The indicators of the wound healing such as collagen-hydroxyproline and hexosamine contents were significantly increased in the treated group indicating accelerated wound healing in the treated animals. The acute phase proteins—haptoglobin and orosomucoid which were increased due to burn injury were found to be decreased significantly in 200 mg/kg body weight extract treated animals. The antioxidant defense mechanism, which was decreased in the liver during burn injury, was found to be enhanced in treated animals. The lipid peroxidation was significantly lowered in the treated group when compared to control animals. Tissue damage marker enzymes- alkaline phosphatase, alanine and aspartate transaminases were significantly lowered in the treated groups in a dose dependant manner. The histopathological analyses of skin tissue also give the evidence of the increased healing potential of the extract after burn injury. PMID:18818737

  4. Contextual control of inhibition with reinforcement: Adaptation and timing mechanisms

    PubMed Central

    Bouton, Mark E.; Frohardt, Russell J.; Sunsay, Ceyhun; Waddell, Jaylyn; Morris, Richard W.

    2010-01-01

    Four experiments with rats studied the effects of switching the context after Pavlovian conditioning. In three conditioned suppression experiments, a large number of conditioning trials created “inhibition with reinforcement” (IWR), in which fear of the conditional stimulus (CS) reached a maximum and then declined despite continued CS – unconditional stimulus pairings. When IWR occurred, a context switch augmented fear of the CS; IWR and augmentation were highly correlated. Neither IWR nor augmentation resulted from inhibition of delay (IOD): In conditioned suppression, IWR and augmentation occurred without IOD (Experiment 3), and in appetitive conditioning (Experiment 4), IOD occurred without IWR or augmentation. IWR may occur in conditioned suppression because the animal adapts to fear of the CS in a context-specific manner. We discuss several implications. PMID:18426305

  5. Adaptive Power Saving Mechanism for 10 Gigabit Class PON Systems

    NASA Astrophysics Data System (ADS)

    Kubo, Ryogo; Kani, Jun-Ichi; Fujimoto, Yukihiro; Yoshimoto, Naoto; Kumozaki, Kiyomi

    This paper proposes a power saving mechanism with variable sleep period to reduce the power consumed by optical network units (ONUs) in passive optical network (PON) systems. In the PON systems based on time division multiplexing (TDM), sleep and periodic wake-up (SPW) control is an effective ONU power saving technique. However, the effectiveness of SPW control is fully realized only if the sleep period changes in accordance with the traffic conditions. This paper proposes an SPW control mechanism with variable sleep period. The proposed mechanism sets the sleep period according to traffic conditions, which greatly improves the power saving effect. In addition, the protocols needed between an optical line terminal (OLT) and ONUs are described on the assumption that the proposed mechanism is applied to 10 Gigabit (10G) class PON systems, i.e. IEEE 802.3av 10G-EPON and FSAN/ITU-T 10G-PON systems. The validity of the proposed mechanism is confirmed by numerical simulations.

  6. Toward a new task assignment and path evolution (TAPE) for missile defense system (MDS) using intelligent adaptive SOM with recurrent neural networks (RNNs).

    PubMed

    Wang, Chi-Hsu; Chen, Chun-Yao; Hung, Kun-Neng

    2015-06-01

    In this paper, a new adaptive self-organizing map (SOM) with recurrent neural network (RNN) controller is proposed for task assignment and path evolution of missile defense system (MDS). We address the problem of N agents (defending missiles) and D targets (incoming missiles) in MDS. A new RNN controller is designed to force an agent (or defending missile) toward a target (or incoming missile), and a monitoring controller is also designed to reduce the error between RNN controller and ideal controller. A new SOM with RNN controller is then designed to dispatch agents to their corresponding targets by minimizing total damaging cost. This is actually an important application of the multiagent system. The SOM with RNN controller is the main controller. After task assignment, the weighting factors of our new SOM with RNN controller are activated to dispatch the agents toward their corresponding targets. Using the Lyapunov constraints, the weighting factors for the proposed SOM with RNN controller are updated to guarantee the stability of the path evolution (or planning) system. Excellent simulations are obtained using this new approach for MDS, which show that our RNN has the lowest average miss distance among the several techniques.

  7. Plant Defense against Insect Herbivores

    PubMed Central

    Fürstenberg-Hägg, Joel; Zagrobelny, Mika; Bak, Søren

    2013-01-01

    Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory induce several internal signals from the wounded tissues, including calcium ion fluxes, phosphorylation cascades and systemic- and jasmonate signaling. These are perceived in undamaged tissues, which thereafter reinforce their defense by producing different, mostly low molecular weight, defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce defense responses. Plants also apply morphological features like waxes, trichomes and latices to make the feeding more difficult for the insects. Extrafloral nectar, food bodies and nesting or refuge sites are produced to accommodate and feed the predators of the herbivores. Meanwhile, herbivorous insects have adapted to resist plant defenses, and in some cases even sequester the compounds and reuse them in their own defense. Both plant defense and insect adaptation involve metabolic costs, so most plant-insect interactions reach a stand-off, where both host and herbivore survive although their development is suboptimal. PMID:23681010

  8. Defense styles of pedophilic offenders.

    PubMed

    Drapeau, Martin; Beretta, Véronique; de Roten, Yves; Koerner, Annett; Despland, Jean-Nicolas

    2008-04-01

    This pilot study investigated the defense styles of pedophile sexual offenders. Interviews with 20 pedophiles and 20 controls were scored using the Defense Mechanisms Rating Scales. Results showed that pedophiles had a significantly lower overall defensive functioning score than the controls. Pedophiles used significantly fewer obsessional-level defenses but more major image-distorting and action-level defenses. Results also suggested differences in the prevalence of individual defenses where pedophiles used more dissociation, displacement, denial, autistic fantasy, splitting of object, projective identification, acting out, and passive aggressive behavior but less intellectualization and rationalization.

  9. Adaptive Mechanisms for Treating Missing Information: A Simulation Study

    ERIC Educational Resources Information Center

    Garcia-Retamero, Rocio; Rieskamp, Jorg

    2008-01-01

    People often make inferences with incomplete information. Previous research has led to a mixed picture of how people treat missing information. To explain these results, the authors follow the Brunswikian perspective on human inference and hypothesize that the mechanism's accuracy for treating missing information depends on how it is distributed…

  10. Fluid Mechanics of Wing Adaptation for Separation Control

    NASA Technical Reports Server (NTRS)

    Chandrasekhara, M. S.; Wilder, M. C.; Carr, L. W.; Davis, Sanford S. (Technical Monitor)

    1997-01-01

    The unsteady fluid mechanics associated with use of a dynamically deforming leading edge airfoil for achieving compressible flow separation control has been experimentally studied. Changing the leading edge curvature at rapid rates dramatically alters the flow vorticity dynamics which is responsible for the many effects observed in the flow.

  11. [Adaptation mechanisms of alpine plants photosynthetic apparatus against adverse stress: a review].

    PubMed

    Wang, Yu-Ping; Gao, Hui-Hui; Liu, Yue-Shan; Mu, Ping; Yu, Xiao-Jun; An, Li-Zhe; Zhang, Feng

    2013-07-01

    Photosynthesis is one of the vital physiological processes easily affected by environmental changes. As a plant group growing in specific low temperature and strong irradiance environment, the photosynthetic apparatus of alpine plants have developed special morphologically and physiologically mechanisms in adapting to this extreme adverse environment. However, due to the high heterogeneity of habitats, there exist great differences in the photo-protection and adaptation mechanisms among different alpine plants. This paper reviewed the recent researches about the morphology and ultramicro-anatomical structure of the chloroplasts in photosynthetic apparatus of alpine plants and the photo-protection and adaptation mechanisms of the plants, and proposed the further research directions on the physiological adaptation of the photosynthesis of alpine plants.

  12. Mechanisms of β-cell functional adaptation to changes in workload.

    PubMed

    Wortham, M; Sander, M

    2016-09-01

    Insulin secretion must be tightly coupled to nutritional state to maintain blood glucose homeostasis. To this end, pancreatic β-cells sense and respond to changes in metabolic conditions, thereby anticipating insulin demands for a given physiological context. This is achieved in part through adjustments of nutrient metabolism, which is controlled at several levels including allosteric regulation, post-translational modifications, and altered expression of metabolic enzymes. In this review, we discuss mechanisms of β-cell metabolic and functional adaptation in the context of two physiological states that alter glucose-stimulated insulin secretion: fasting and insulin resistance. We review current knowledge of metabolic changes that occur in the β-cell during adaptation and specifically discuss transcriptional mechanisms that underlie β-cell adaptation. A more comprehensive understanding of how β-cells adapt to changes in nutrient state could identify mechanisms to be co-opted for therapeutically modulating insulin secretion in metabolic disease. PMID:27615135

  13. Genome and Transcriptome Analyses Provide Insight into the Euryhaline Adaptation Mechanism of Crassostrea gigas

    PubMed Central

    Zhang, Linlin; Li, Chunyan; Li, Li; She, Zhicai; Huang, Baoyu; Zhang, Guofan

    2013-01-01

    Background The Pacific oyster, Crassostrea gigas, has developed special mechanisms to regulate its osmotic balance to adapt to fluctuations of salinities in coastal zones. To understand the oyster’s euryhaline adaptation, we analyzed salt stress effectors metabolism pathways under different salinities (salt 5, 10, 15, 20, 25, 30 and 40 for 7 days) using transcriptome data, physiology experiment and quantitative real-time PCR. Results Transcriptome data uncovered 189, 480, 207 and 80 marker genes for monitoring physiology status of oysters and the environment conditions. Three known salt stress effectors (involving ion channels, aquaporins and free amino acids) were examined. The analysis of ion channels and aquaporins indicated that 7 days long-term salt stress inhibited voltage-gated Na+/K+ channel and aquaporin but increased calcium-activated K+ channel and Ca2+ channel. As the most important category of osmotic stress effector, we analyzed the oyster FAAs metabolism pathways (including taurine, glycine, alanine, beta-alanine, proline and arginine) and explained FAAs functional mechanism for oyster low salinity adaptation. FAAs metabolism key enzyme genes displayed expression differentiation in low salinity adapted individuals comparing with control which further indicated that FAAs played important roles for oyster salinity adaptation. A global metabolic pathway analysis (iPath) of oyster expanded genes displayed a co-expansion of FAAs metabolism in C. gigas compared with seven other species, suggesting oyster’s powerful ability regarding FAAs metabolism, allowing it to adapt to fluctuating salinities, which may be one important mechanism underlying euryhaline adaption in oyster. Additionally, using transcriptome data analysis, we uncovered salt stress transduction networks in C. gigas. Conclusions Our results represented oyster salt stress effectors functional mechanisms under salt stress conditions and explained the expansion of FAAs metabolism pathways as

  14. Increased Antioxidant Defense Mechanism in Human Adventitia-Derived Progenitor Cells Is Associated with Therapeutic Benefit in Ischemia

    PubMed Central

    Iacobazzi, Dominga; Mangialardi, Giuseppe; Gubernator, Miriam; Hofner, Manuela; Wielscher, Matthias; Vierlinger, Klemens; Reni, Carlotta; Oikawa, Atsuhiko; Spinetti, Gaia; Vono, Rosa; Sangalli, Elena; Montagnani, Monica

    2014-01-01

    Abstract Aims: Vascular wall-resident progenitor cells hold great promise for cardiovascular regenerative therapy. This study evaluates the impact of oxidative stress on the viability and functionality of adventitia-derived progenitor cells (APCs) from vein remnants of coronary artery bypass graft (CABG) surgery. We also investigated the antioxidant enzymes implicated in the resistance of APCs to oxidative stress-induced damage and the effect of interfering with one of them, the extracellular superoxide dismutase (EC-SOD/SOD3), on APC therapeutic action in a model of peripheral ischemia. Results: After exposure to hydrogen peroxide, APCs undergo apoptosis to a smaller extent than endothelial cells (ECs). This was attributed to up-regulation of antioxidant enzymes, especially SODs and catalase. Pharmacological inhibition of SODs increases reactive oxygen species (ROS) levels in APCs and impairs their survival. Likewise, APC differentiation results in SOD down-regulation and ROS-induced apoptosis. Oxidative stress increases APC migratory activity, while being inhibitory for ECs. In addition, oxidative stress does not impair APC capacity to promote angiogenesis in vitro. In a mouse limb ischemia model, an injection of naïve APCs, but not SOD3-silenced APCs, helps perfusion recovery and neovascularization, thus underlining the importance of this soluble isoform in protection from ischemia. Innovation: This study newly demonstrates that APCs are endowed with enhanced detoxifier and antioxidant systems and that SOD3 plays an important role in their therapeutic activity in ischemia. Conclusions: APCs from vein remnants of CABG patients express antioxidant defense mechanisms, which enable them to resist stress. These properties highlight the potential of APCs in cardiovascular regenerative medicine. Antioxid. Redox Signal. 21, 1591–1604. PMID:24512058

  15. Spike initiating dynamics of the neuron with different adaptation mechanisms to extracellular electric fields

    NASA Astrophysics Data System (ADS)

    Yi, Guosheng; Wang, Jiang; Deng, Bin; Wei, Xile

    2015-05-01

    In this paper, we address how adaptation mediated by different biophysical mechanisms modulates neuronal spike initiating dynamics to extracellular electric fields. We incorporate two adaptation currents, i.e., voltage-sensitive potassium current (IM) and calcium-sensitive potassium current (IAHP), into a reduced two-compartment neuron model, and extensively investigate the modeling behavior to a range of electric fields. With phase plane analysis, it is shown whether neuron continues to spike depends on whether adaptation currents could be sufficiently activated to stabilize membrane potential at subthreshold voltages. With stability and bifurcation analysis, we find the steady-state spiking in the neuron with IM occurs through a Hopf bifurcation, whereas it is generated through a saddle-node on invariant circle (SNIC) bifurcation in the cases of IAHP or no adaptation. By identifying the biophysical basis for these dynamics, we observe that IM could alter the competitive outcomes between kinetically mismatched opposite currents to result in a Hopf bifurcation, while IAHP cannot alter these competitive outcomes. From this, we conclude that different modulations of spike initiating dynamics derive from the biophysical mechanism responsible for distinct adaptation currents. Our study suggests that the adaptation mediated by different mechanisms indeed has different effects on neuronal dynamics to electric field stimulus. It could contribute to uncover the underlying mechanism of how neuron encodes electric field signals.

  16. Use it or lose it: multiscale skeletal muscle adaptation to mechanical stimuli.

    PubMed

    Wisdom, Katrina M; Delp, Scott L; Kuhl, Ellen

    2015-04-01

    Skeletal muscle undergoes continuous turnover to adapt to changes in its mechanical environment. Overload increases muscle mass, whereas underload decreases muscle mass. These changes are correlated with, and enabled by, structural alterations across the molecular, subcellular, cellular, tissue, and organ scales. Despite extensive research on muscle adaptation at the individual scales, the interaction of the underlying mechanisms across the scales remains poorly understood. Here, we present a thorough review and a broad classification of multiscale muscle adaptation in response to a variety of mechanical stimuli. From this classification, we suggest that a mathematical model for skeletal muscle adaptation should include the four major stimuli, overstretch, understretch, overload, and underload, and the five key players in skeletal muscle adaptation, myosin heavy chain isoform, serial sarcomere number, parallel sarcomere number, pennation angle, and extracellular matrix composition. Including this information in multiscale computational models of muscle will shape our understanding of the interacting mechanisms of skeletal muscle adaptation across the scales. Ultimately, this will allow us to rationalize the design of exercise and rehabilitation programs, and improve the long-term success of interventional treatment in musculoskeletal disease.

  17. Review. Use it or lose it: Multiscale skeletal muscle adaptation to mechanical stimuli

    PubMed Central

    Wisdom, Katrina M.; Delp, Scott L.; Kuhl, Ellen

    2014-01-01

    Skeletal muscle undergoes continuous turnover to adapt to changes in its mechanical environment. Overload increases muscle mass, whereas underload decreases muscle mass. These changes are correlated with, and enabled by, structural alterations across the molecular, subcellular, cellular, tissue, and organ scales. Despite extensive research on muscle adaptation at the individual scales, the interaction of the underlying mechanisms across the scales remains poorly understood. Here we present a thorough review and a broad classification of multiscale muscle adaptation in response to a variety of mechanical stimuli. From this classification, we suggest that a mathematical model for skeletal muscle adaptation should include the four major stimuli, overstretch, understretch, overload, and underload, and the five key players in skeletal muscle adaptation, myosin heavy chain isoform, serial sarcomere number, parallel sarcomere number, pennation angle, and extracellular matrix composition. Including this information in multiscale computational models of muscle will shape our understanding of the interacting mechanisms of skeletal muscle adaptation across the scales. Ultimately, this will allow us to rationalize the design of exercise and rehabilitation programs, and improve the long-term success of interventional treatment in musculoskeletal disease. PMID:25199941

  18. Aortic pulse pressure homeostasis emerges from physiological adaptation of systemic arteries to local mechanical stresses.

    PubMed

    Nguyen, Phuc H; Tuzun, Egemen; Quick, Christopher M

    2016-09-01

    Aortic pulse pressure arises from the interaction of the heart, the systemic arterial system, and peripheral microcirculations. The complex interaction between hemodynamics and arterial remodeling precludes the ability to experimentally ascribe changes in aortic pulse pressure to particular adaptive responses. Therefore, the purpose of the present work was to use a human systemic arterial system model to test the hypothesis that pulse pressure homeostasis can emerge from physiological adaptation of systemic arteries to local mechanical stresses. First, we assumed a systemic arterial system that had a realistic topology consisting of 121 arterial segments. Then the relationships of pulsatile blood pressures and flows in arterial segments were characterized by standard pulse transmission equations. Finally, each arterial segment was assumed to remodel to local stresses following three simple rules: 1) increases in endothelial shear stress increases radius, 2) increases in wall circumferential stress increases wall thickness, and 3) increases in wall circumferential stress decreases wall stiffness. Simulation of adaptation by iteratively calculating pulsatile hemodynamics, mechanical stresses, and vascular remodeling led to a general behavior in response to mechanical perturbations: initial increases in pulse pressure led to increased arterial compliances, and decreases in pulse pressure led to decreased compliances. Consequently, vascular adaptation returned pulse pressures back toward baseline conditions. This behavior manifested when modeling physiological adaptive responses to changes in cardiac output, changes in peripheral resistances, and changes in local arterial radii. The present work, thus, revealed that pulse pressure homeostasis emerges from physiological adaptation of systemic arteries to local mechanical stresses.

  19. Herbivores can select for mixed defensive strategies in plants.

    PubMed

    Carmona, Diego; Fornoni, Juan

    2013-01-01

    Resistance and tolerance are the most important defense mechanisms against herbivores. Initial theoretical studies considered both mechanisms functionally redundant, but more recent empirical studies suggest that these mechanisms may complement each other, favoring the presence of mixed defense patterns. However, the expectation of redundancy between tolerance and resistance remains unsupported. In this study, we tested this assumption following an ecological genetics field experiment in which the presence/absence of two herbivores (Lema daturaphila and Epitrix parvula) of Datura stramonium were manipulated. In each of three treatments, genotypic selection analyses were performed and selection patterns compared. Our results indicated that selection on resistance and tolerance was significantly different between the two folivores. Tolerance and resistance are not redundant defense strategies in D. stramonium but instead functioned as complementary defenses against both beetle species, favoring the evolution of a mixed defense strategy. Although each herbivore was selected for different defense strategies, the observed average tolerance and resistance were closer to the adaptive peak predicted against E. parvula and both beetles together. In our experimental population, natural selection imposed by herbivores can favor the evolution of mixed defense strategies in plants, accounting for the presence of intermediate levels of tolerance and resistance. PMID:23171270

  20. Molecular mechanisms underlying the exceptional adaptations of batoid fins

    PubMed Central

    Nakamura, Tetsuya; Klomp, Jeff; Pieretti, Joyce; Schneider, Igor; Gehrke, Andrew R.; Shubin, Neil H.

    2015-01-01

    Extreme novelties in the shape and size of paired fins are exemplified by extinct and extant cartilaginous and bony fishes. Pectoral fins of skates and rays, such as the little skate (Batoid, Leucoraja erinacea), show a strikingly unique morphology where the pectoral fin extends anteriorly to ultimately fuse with the head. This results in a morphology that essentially surrounds the body and is associated with the evolution of novel swimming mechanisms in the group. In an approach that extends from RNA sequencing to in situ hybridization to functional assays, we show that anterior and posterior portions of the pectoral fin have different genetic underpinnings: canonical genes of appendage development control posterior fin development via an apical ectodermal ridge (AER), whereas an alternative Homeobox (Hox)–Fibroblast growth factor (Fgf)–Wingless type MMTV integration site family (Wnt) genetic module in the anterior region creates an AER-like structure that drives anterior fin expansion. Finally, we show that GLI family zinc finger 3 (Gli3), which is an anterior repressor of tetrapod digits, is expressed in the posterior half of the pectoral fin of skate, shark, and zebrafish but in the anterior side of the pelvic fin. Taken together, these data point to both highly derived and deeply ancestral patterns of gene expression in skate pectoral fins, shedding light on the molecular mechanisms behind the evolution of novel fin morphologies. PMID:26644578

  1. Molecular mechanisms underlying the exceptional adaptations of batoid fins.

    PubMed

    Nakamura, Tetsuya; Klomp, Jeff; Pieretti, Joyce; Schneider, Igor; Gehrke, Andrew R; Shubin, Neil H

    2015-12-29

    Extreme novelties in the shape and size of paired fins are exemplified by extinct and extant cartilaginous and bony fishes. Pectoral fins of skates and rays, such as the little skate (Batoid, Leucoraja erinacea), show a strikingly unique morphology where the pectoral fin extends anteriorly to ultimately fuse with the head. This results in a morphology that essentially surrounds the body and is associated with the evolution of novel swimming mechanisms in the group. In an approach that extends from RNA sequencing to in situ hybridization to functional assays, we show that anterior and posterior portions of the pectoral fin have different genetic underpinnings: canonical genes of appendage development control posterior fin development via an apical ectodermal ridge (AER), whereas an alternative Homeobox (Hox)-Fibroblast growth factor (Fgf)-Wingless type MMTV integration site family (Wnt) genetic module in the anterior region creates an AER-like structure that drives anterior fin expansion. Finally, we show that GLI family zinc finger 3 (Gli3), which is an anterior repressor of tetrapod digits, is expressed in the posterior half of the pectoral fin of skate, shark, and zebrafish but in the anterior side of the pelvic fin. Taken together, these data point to both highly derived and deeply ancestral patterns of gene expression in skate pectoral fins, shedding light on the molecular mechanisms behind the evolution of novel fin morphologies. PMID:26644578

  2. Salicylic acid-mediated and RNA-silencing defense mechanisms cooperate in the restriction of systemic spread of plum pox virus in tobacco.

    PubMed

    Alamillo, Josefa M; Saénz, Pilar; García, Juan Antonio

    2006-10-01

    Plum pox virus (PPV) is able to replicate in inoculated leaves of Nicotiana tabacum, but is defective in systemic movement in this host. However, PPV produces a systemic infection in transgenic tobacco expressing the silencing suppressor P1/HC-Pro from tobacco etch virus (TEV). In this work we show that PPV is able to move to upper non-inoculated leaves of tobacco plants expressing bacterial salicylate hydroxylase (NahG) that degrades salicylic acid (SA). Replication and accumulation of PPV is higher in the locally infected leaves of plants deficient in SA or expressing TEV P1/HC-Pro silencing suppressor. Accumulation of viral derived small RNAs was reduced in the NahG transgenic plants, suggesting that SA might act as an enhancer of the RNA-silencing antiviral defense in tobacco. Besides, expression of SA-mediated defense transcripts, such as those of pathogenesis-related (PR) proteins PR-1 and PR-2 or alternative oxidase-1, as well as that of the putative RNA-dependent RNA polymerase NtRDR1, is induced in response to PPV infection, and the expression patterns of these defense transcripts are altered in the TEV P1/HC-Pro transgenic plants. Long-distance movement of PPV is highly enhanced in NahG x P1/HC-Pro double-transgenic plants and systemic symptoms in these plants reveal that the expression of an RNA-silencing suppressor and the lack of SA produce additive but distinct effects. Our results suggest that SA might act as an enhancer of the RNA-silencing antiviral defense in tobacco, and that silencing suppressors, such as P1/HC-Pro, also alter the SA-mediated defense. Both an RNA-silencing and an SA-mediated defense mechanism could act together to limit PPV infection.

  3. Defenseive Structuring and Environmental Stress

    ERIC Educational Resources Information Center

    Siegel, Bernard J.

    1970-01-01

    This essay explores a kind of adaptation, referred to as defenseive structuring, that recurs with great regularity among groups that perceive themselves as exposed to environmental stress of long duration with which they cannot cope directly and aggressively." (Author)

  4. White Spot Syndrome Virus Protein Kinase 1 Defeats the Host Cell's Iron-Withholding Defense Mechanism by Interacting with Host Ferritin

    PubMed Central

    Lin, Shin-Jen; Lee, Der-Yen; Wang, Hao-Ching; Kang, Shih-Ting; Hwang, Pung-Pung; Kou, Guang-Hsiung; Huang, Ming-Fen

    2014-01-01

    ABSTRACT Iron is an essential nutrient for nearly all living organisms, including both hosts and invaders. Proteins such as ferritin regulate the iron levels in a cell, and in the event of a pathogenic invasion, the host can use an iron-withholding mechanism to restrict the availability of this essential nutrient to the invading pathogens. However, pathogens use various strategies to overcome this host defense. In this study, we demonstrated that white spot syndrome virus (WSSV) protein kinase 1 (PK1) interacted with shrimp ferritin in the yeast two-hybrid system. A pulldown assay and 27-MHz quartz crystal microbalance (QCM) analysis confirmed the interaction between PK1 and both ferritin and apoferritin. PK1 did not promote the release of iron ions from ferritin, but it prevented apoferritin from binding ferrous ions. When PK1 was overexpressed in Sf9 cells, the cellular labile iron pool (LIP) levels were elevated significantly. Immunoprecipitation and atomic absorption spectrophotometry (AAS) further showed that the number of iron ions bound by ferritin decreased significantly at 24 h post-WSSV infection. Taken together, these results suggest that PK1 prevents apoferritin from iron loading, and thus stabilizes the cellular LIP levels, and that WSSV uses this novel mechanism to counteract the host cell's iron-withholding defense mechanism. IMPORTANCE We show here that white spot syndrome virus (WSSV) ensures the availability of iron by using a previously unreported mechanism to defeat the host cell's iron-withholding defense mechanism. This defense is often implemented by ferritin, which can bind up to 4,500 iron atoms and acts to sequester free iron within the cell. WSSV's novel counterstrategy is mediated by a direct protein-protein interaction between viral protein kinase 1 (PK1) and host ferritin. PK1 interacts with both ferritin and apoferritin, suppresses apoferritin's ability to sequester free iron ions, and maintains the intracellular labile iron pool (LIP

  5. Adaptation Mechanism of the Aspartate Receptor: Electrostatics of the Adaptation Subdomain Play a Key Role in Modulating Kinase Activity†

    PubMed Central

    Starrett, Diane J.; Falke, Joseph J.

    2010-01-01

    The aspartate receptor of the Escherichia coli and Salmonella typhimurium chemotaxis pathway generates a transmembrane signal that regulates the activity of the cytoplasmic kinase CheA. Previous studies have identified a region of the cytoplasmic domain that is critical to receptor adaptation and kinase regulation. This region, termed the adaptation subdomain, contains a high density of acidic residues, including specific glutamate residues that serve as receptor adaptation sites. However, the mechanism of signal propagation through this region remains poorly understood. This study uses site-directed mutagenesis to neutralize each acidic residue within the subdomain to probe the hypothesis that electrostatics in this region play a significant role in the mechanism of kinase activation and modulation. Each point mutant was tested for its ability to regulate chemotaxis in vivo and kinase activity in vitro. Four point mutants (D273N, E281Q, D288N, and E477Q) were found to superactivate the kinase relative to the wild-type receptor, and all four of these kinase-activating substitutions are located along the same intersubunit interface as the adaptation sites. These activating substitutions retained the wild-type ability of the attractant-occupied receptor to inhibit kinase activity. When combined in a quadruple mutant (D273N/E281Q/D288N/E477Q), the four charge-neutralizing substitutions locked the receptor in a kinase-superactivating state that could not be fully inactivated by the attractant. Similar lock-on character was observed for a charge reversal substitution, D273R. Together, these results implicate the electrostatic interactions at the intersubunit interface as a major player in signal transduction and kinase regulation. The negative charge in this region destabilizes the local structure in a way that enhances conformational dynamics, as detected by disulfide trapping, and this effect is reversed by charge neutralization of the adaptation sites. Finally, two

  6. Borderline personality organization in violent offenders: correlations of identity diffusion and primitive defense mechanisms with antisocial features, neuroticism, and interpersonal problems.

    PubMed

    Leichsenring, Falk; Kunst, Heike; Hoyer, Jürgen

    2003-01-01

    Although theoretical assumptions and empirical evidence suggest an association between borderline personality disorder (BPD) and antisocial behavior or even antisocial personality disorder (APD), there is no study relating the psychodynamic aspects of BPD to antisocial behavior. In this study, the authors tested the correlation between the structural criteria of borderline personality organization (BPO)--that is, identity diffusion, primitive defense mechanisms, and reality testing--and antisocial features, neuroticism, and interpersonal problems. A sample of imprisoned violent offenders (N = 91) was studied using the Antisocial Personality Questionnaire (APQ), the Borderline Personality Inventory (BPI), the Neo-Five-Factor-Inventory (Neo-FFI), and the Inventory of Interpersonal Problems (IIP). Significant correlations were predicted and found between the BPI scales of identity diffusion, primitive defense mechanisms, impaired reality testing, and fear of closeness and antisocial features, neuroticism, agreeableness, and interpersonal problems. The results are consistent with both object relations theory and attachment theory.

  7. Dysfunctionality of the xylem in Olea europaea L. Plants associated with the infection process by Verticillium dahliae Kleb. Role of phenolic compounds in plant defense mechanism.

    PubMed

    Báidez, Ana G; Gómez, Pedro; Del Río, José A; Ortuño, Ana

    2007-05-01

    Xylem ultrastructural modification and the possible participation of phenolic compounds in the natural defense or resistance mechanisms of olive plants infected with Verticillium dahliae Kleb. were studied. Microscopic study showed that the mycelium propagated and passed from one element to another through the pit. The formation of tyloses and aggregates contributed to obstruction of the xylem lumen. In vivo changes in the levels of these phenolic compounds in infected olive plants and their antifungal activity against Verticillium dahliae Kleb., as revealed by in vitro study, strongly suggest that they are involved in natural defense or resistance mechanisms in this plant material, the most active being quercetin and luteolin aglycons, followed by rutin, oleuropein, luteolin-7-glucoside, tyrosol, p-coumaric acid, and catechin. . PMID:17394331

  8. Adaptive implicit-explicit finite element algorithms for fluid mechanics problems

    NASA Technical Reports Server (NTRS)

    Tezduyar, T. E.; Liou, J.

    1988-01-01

    The adaptive implicit-explicit (AIE) approach is presented for the finite-element solution of various problems in computational fluid mechanics. In the AIE approach, the elements are dynamically (adaptively) arranged into differently treated groups. The differences in treatment could be based on considerations such as the cost efficiency, the type of spatial or temporal discretization employed, the choice of field equations, etc. Several numerical tests are performed to demonstrate that this approach can achieve substantial savings in CPU time and memory.

  9. Adaptive Spontaneous Transitions between Two Mechanisms of Numerical Averaging.

    PubMed

    Brezis, Noam; Bronfman, Zohar Z; Usher, Marius

    2015-01-01

    We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two. PMID:26041580

  10. Adaptive Spontaneous Transitions between Two Mechanisms of Numerical Averaging

    PubMed Central

    Brezis, Noam; Bronfman, Zohar Z.; Usher, Marius

    2015-01-01

    We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two. PMID:26041580

  11. Innate and adaptive immunity in bacteria: mechanisms of programmed genetic variation to fight bacteriophages.

    PubMed

    Bikard, David; Marraffini, Luciano A

    2012-02-01

    Bacteria are constantly challenged by bacteriophages (viruses that infect bacteria), the most abundant microorganism on earth. Bacteria have evolved a variety of immunity mechanisms to resist bacteriophage infection. In response, bacteriophages can evolve counter-resistance mechanisms and launch a 'virus versus host' evolutionary arms race. In this context, rapid evolution is fundamental for the survival of the bacterial cell. Programmed genetic variation mechanisms at loci involved in immunity against bacteriophages generate diversity at a much faster rate than random point mutation and enable bacteria to quickly adapt and repel infection. Diversity-generating retroelements (DGRs) and phase variation mechanisms enhance the generic (innate) immune response against bacteriophages. On the other hand, the integration of small bacteriophage sequences in CRISPR loci provide bacteria with a virus-specific and sequence-specific adaptive immune response. Therefore, although using different molecular mechanisms, both prokaryotes and higher organisms rely on programmed genetic variation to increase genetic diversity and fight rapidly evolving infectious agents.

  12. The GraS Sensor in Staphylococcus aureus Mediates Resistance to Host Defense Peptides Differing in Mechanisms of Action

    PubMed Central

    Chaili, Siyang; Cheung, Ambrose L.; Bayer, Arnold S.; Xiong, Yan Q.; Waring, Alan J.; Memmi, Guido; Donegan, Niles; Yang, Soo-Jin

    2015-01-01

    Staphylococcus aureus uses the two-component regulatory system GraRS to sense and respond to host defense peptides (HDPs). However, the mechanistic impact of GraS or its extracellular sensing loop (EL) on HDP resistance is essentially unexplored. Strains with null mutations in the GraS holoprotein (ΔgraS) or its EL (ΔEL) were compared for mechanisms of resistance to HDPs of relevant immune sources: neutrophil α-defensin (human neutrophil peptide 1 [hNP-1]), cutaneous β-defensin (human β-defensin 2 [hBD-2]), or the platelet kinocidin congener RP-1. Actions studied by flow cytometry included energetics (ENR); membrane permeabilization (PRM); annexin V binding (ANX), and cell death protease activation (CDP). Assay conditions simulated bloodstream (pH 7.5) or phagolysosomal (pH 5.5) pH contexts. S. aureus strains were more susceptible to HDPs at pH 7.5 than at pH 5.5, and each HDP exerted a distinct effect signature. The impacts of ΔgraS and ΔΕL on HDP resistance were peptide and pH dependent. Both mutants exhibited defects in ANX response to hNP-1 or hBD-2 at pH 7.5, but only hNP-1 did so at pH 5.5. Both mutants exhibited hyper-PRM, -ANX, and -CDP responses to RP-1 at both pHs and hypo-ENR at pH 5.5. The actions correlated with ΔgraS or ΔΕL hypersusceptibility to hNP-1 or RP-1 (but not hBD-2) at pH 7.5 and to all study HDPs at pH 5.5. An exogenous EL mimic protected mutant strains from hNP-1 and hBD-2 but not RP-1, indicating that GraS and its EL play nonredundant roles in S. aureus survival responses to specific HDPs. These findings suggest that GraS mediates specific resistance countermeasures to HDPs in immune contexts that are highly relevant to S. aureus pathogenesis in humans. PMID:26597988

  13. Comparison of adaptive algorithms for the control of tonal disturbances in mechanical systems

    NASA Astrophysics Data System (ADS)

    Zilletti, M.; Elliott, S. J.; Cheer, J.

    2016-09-01

    This paper presents a study on the performance of adaptive control algorithms designed to reduce the vibration of mechanical systems excited by a harmonic disturbance. The mechanical system consists of a mass suspended on a spring and a damper. The system is equipped with a force actuator in parallel with the suspension. The control signal driving the actuator is generated by adjusting the amplitude and phase of a sinusoidal reference signal at the same frequency as the excitation. An adaptive feedforward control algorithm is used to adapt the amplitude and phase of the control signal, to minimise the mean square velocity of the mass. Two adaptation strategies are considered in which the control signal is either updated after each period of the oscillation or at every time sample. The first strategy is traditionally used in vibration control in helicopters for example; the second strategy is normally referred to as the filtered-x least mean square algorithm and is often used to control engine noise in cars. The two adaptation strategies are compared through a parametric study, which investigates the influence of the properties of both the mechanical system and the control system on the convergence speed of the two algorithms.

  14. Mechanism of HSV infection through soluble adapter-mediated virus bridging to the EGF receptor

    SciTech Connect

    Nakano, Kenji; Kobayashi, Masatoshi; Nakamura, Kei-ichiro; Nakanishi, Takeshi; Asano, Ryutaro; Kumagai, Izumi; Tahara, Hideaki; Kuwano, Michihiko; Cohen, Justus B.; Glorioso, Joseph C.

    2011-04-25

    Herpes simplex virus entry into cells requires the binding of envelope glycoprotein D (gD) to an entry receptor. Depending on the cell, entry occurs by different mechanisms, including fusion at the cell surface or endocytosis. Here we examined the entry mechanism through a non-HSV receptor mediated by a soluble bi-specific adapter protein composed of recognition elements for gD and the EGF receptor (EGFR). Virus entered into endosomes using either EGF or an EGFR-specific single chain antibody (scFv) for receptor recognition. Infection was less efficient with the EGF adapter which could be attributed to its weaker binding to a viral gD. Infection mediated by the scFv adapter was pH sensitive, indicating that gD-EGFR bridging alone was insufficient for capsid release from endosomes. We also show that the scFv adapter enhanced infection of EGFR-expressing tumor tissue in vivo. Our results indicate that adapters may retarget HSV infection without drastically changing the entry mechanism.

  15. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  16. Microbial community succession mechanism coupling with adaptive evolution of adsorption performance in chalcopyrite bioleaching.

    PubMed

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    The community succession mechanism of Acidithiobacillus sp. coupling with adaptive evolution of adsorption performance were systematically investigated. Specifically, the μmax of attached and free cells was increased and peak time was moved ahead, indicating both cell growth of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was promoted. In the mixed strains system, the domination courses of A. thiooxidans was dramatically shortened from 22th day to 15th day, although community structure finally approached to the normal system. Compared to A. ferrooxidans, more positive effects of adaptive evolution on cell growth of A. thiooxidans were shown in either single or mixed strains system. Moreover, higher concentrations of sulfate and ferric ions indicated that both sulfur and iron metabolism was enhanced, especially of A. thiooxidans. Consistently, copper ion production was improved from 65.5 to 88.5 mg/L. This new adaptive evolution and community succession mechanism may be useful for guiding similar bioleaching processes.

  17. FPGA-based adaptive backstepping fuzzy control for a micro-positioning Scott-Russell mechanism

    NASA Astrophysics Data System (ADS)

    Fung, Rong-Fong; Weng, Ming-Hong; Kung, Ying-Shieh

    2009-11-01

    This paper utilizes the field programmable gate array (FPGA) and Nios II embedded processor technologies to design a controller IC for a micro-positioning Scott-Russell (SR) mechanism, which is driven by a piezoelectric actuator (PA) and its hysteresis phenomenon is described by Bouc-Wen hysteresis model. For the controller design, the adaptive backstepping fuzzy control (ABFC) method is developed to compensate the PA's hysteresis and achieve the motion tracking control. The fuzzy logic method (FLM) is utilized to find the best adaptation gain of the adaptation law and control gain of the stabilization controls. This ABFC controller method can improve the transient and asymptotic tracking performances, and make the SR mechanism keep good working performance when external disturbances is added in the control system. Finally, we successfully apply the system-on-a-programmable-chip (SoPC) technologies to develop the motion controller IC, and achieve the advantages of reduced space, high performance and low cost.

  18. Adolescent Suicide and Defensive Style.

    ERIC Educational Resources Information Center

    Recklitis, Christopher J.; And Others

    1992-01-01

    Examined relationship between ego defense mechanisms, diagnoses, and suicidality among 200 adolescent psychiatric patients classified as suicide attempters, suicidal ideators, and nonsuicidal patients. Using Defense Mechanisms Inventory, found the suicidal adolescents score higher on turning-against-self and lower on reversal, as compared to…

  19. Glutathione and mitochondria determine acute defense responses and adaptive processes in cadmium-induced oxidative stress and toxicity of the kidney.

    PubMed

    Nair, Ambily Ravindran; Lee, Wing-Kee; Smeets, Karen; Swennen, Quirine; Sanchez, Amparo; Thévenod, Frank; Cuypers, Ann

    2015-12-01

    Cadmium (Cd(2+)) induces oxidative stress that ultimately defines cell fate and pathology. Mitochondria are the main energy-producing organelles in mammalian cells, but they also have a central role in formation of reactive oxygen species, cell injury, and death signaling. As the kidney is the major target in Cd(2+) toxicity, the roles of oxidative signature and mitochondrial function and biogenesis in Cd(2+)-related stress outcomes were investigated in vitro in cultured rat kidney proximal tubule cells (PTCs) (WKPT-0293 Cl.2) for acute Cd(2+) toxicity (1-30 µM, 24 h) and in vivo in Fischer 344 rats for sub-chronic Cd(2+) toxicity (1 mg/kg CdCl2 subcutaneously, 13 days). Whereas 30 µM Cd(2+) caused ~50 % decrease in cell viability, apoptosis peaked at 10 µM Cd(2+) in PTCs. A steep, dose-dependent decline in reduced glutathione (GSH) content occurred after acute exposure and an increase of the oxidized glutathione (GSSG)/GSH ratio. Quantitative PCR analyses evidenced increased antioxidative enzymes (Sod1, Gclc, Gclm), proapoptotic Bax, metallothioneins 1A/2A, and decreased antiapoptotic proteins (Bcl-xL, Bcl-w). The positive regulator of mitochondrial biogenesis Pparγ and mitochondrial DNA was increased, and cellular ATP was unaffected with Cd(2+) (1-10 µM). In vivo, active caspase-3, and hence apoptosis, was detected by FLIVO injection in the kidney cortex of Cd(2+)-treated rats together with an increase in Bax mRNA. However, antiapoptotic genes (Bcl-2, Bcl-xL, Bcl-w) were also upregulated. Both GSSG and GSH increased with chronic Cd(2+) exposure with no change in GSSG/GSH ratio and augmented expression of antioxidative enzymes (Gpx4, Prdx2). Mitochondrial DNA, mitofusin 2, and Pparα were increased indicating enhanced mitochondrial biogenesis and fusion. Hence, these results demonstrate a clear involvement of higher mitochondria copy numbers or mass and mitochondrial function in acute defense against oxidative stress induced by Cd(2+) in renal PTCs as well as

  20. Lysozyme- and chitinase activity in latex bearing plants of genus Euphorbia--A contribution to plant defense mechanism.

    PubMed

    Sytwala, Sonja; Günther, Florian; Melzig, Matthias F

    2015-10-01

    Occurrence of latices in plants is widespread, there are 40 families of plants characterized to establish lactiferous structures. Latices exhibit a constitutive part of plant defense due to the stickiness. The appearance of proteins incorporated in latices is well characterized, and hydrolytic active proteins are considerable. A lot of plants constitute so-called pathogenesis-related (PR) proteins, to overcome stressful conditions. In our investigation we are focused on latex bearing plants of Euphorbiaceae Juss., and investigated the appearance of chitinase- and lysozyme activity in particular. The present outcomes represent a comprehensive study, relating to the occurrence of lysozyme and chitinase activity of genus Euphorbia at the first time. 110 different species of genus Euphorbia L. were tested, and the appearance of chitinase and lysozyme were determined in different quantities. The appearance itself, and the physicochemical properties of latices indicate an efficient interaction for plant defense against pathogen attack.

  1. A transcriptional profile of metallophyte Viola baoshanensis involved in general and species-specific cadmium-defense mechanisms.

    PubMed

    Zhang, Jun; Hu, Min; Li, Jin-Tian; Guan, Jian-Ping; Yang, Bin; Shu, Wen-Sheng; Liao, Bin

    2009-05-15

    Viola baoshanensis Shu, Liu et Lan is a newly identified metallophyte, and its defensive strategies against heavy metals are still unclear. In the present study, we firstly constructed a root cDNA library of the plant subjected to 300muM Cd for 48h by using suppression subtractive hybridization (SSH), and 43 unique cDNA fragments were further isolated from the library. Sequence homology analysis showed that half of the identified genes were involved in general stress defense, such as antioxidative enzymes, protein degradation and stress signal transduction. After RT-PCR and RACE analysis, a Cd-responsive gene Vb40 was identified, which could deduce a novel cysteine-rich mini-protein. Meanwhile, five cyclotide precursor genes (VbCP1-VbCP5) were also identified. The Vb40 and the VbCP1-VbCP5 were further investigated by yeast expression analysis, and they could improve copper (Cu) tolerance in hosted yeast, indicating that these species-specific genes possibly functioned in V. baoshanensis heavy metals tolerance. Our results suggested that heavy metal tolerance in V. baoshanensis relied on both general and species-specific defense.

  2. Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod.

    PubMed

    Hut, R A; Beersma, D G M

    2011-07-27

    Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.

  3. Metabolic insight into mechanisms of high-altitude adaptation in Tibetans.

    PubMed

    Ge, Ri-Li; Simonson, Tatum S; Cooksey, Robert C; Tanna, Uran; Qin, Ga; Huff, Chad D; Witherspoon, David J; Xing, Jinchuan; Zhengzhong, Bai; Prchal, Josef T; Jorde, Lynn B; McClain, Donald A

    2012-06-01

    Recent studies have identified genes involved in high-altitude adaptation in Tibetans. Genetic variants/haplotypes within regions containing three of these genes (EPAS1, EGLN1, and PPARA) are associated with relatively decreased hemoglobin levels observed in Tibetans at high altitude, providing corroborative evidence for genetic adaptation to this extreme environment. The mechanisms that afford adaptation to high-altitude hypoxia, however, remain unclear. Considering the strong metabolic demands imposed by hypoxia, we hypothesized that a shift in fuel preference to glucose oxidation and glycolysis at the expense of fatty acid oxidation would improve adaptation to decreased oxygen availability. Correlations between serum free fatty acid and lactate concentrations in Tibetan groups living at high altitude and putatively selected haplotypes provide insight into this hypothesis. An EPAS1 haplotype that exhibits a signal of positive selection is significantly associated with increased lactate concentration, the product of anaerobic glycolysis. Furthermore, the putatively advantageous PPARA haplotype is correlated with serum free fatty acid concentrations, suggesting a possible decrease in the activity of fatty acid oxidation. Although further studies are required to assess the molecular mechanisms underlying these patterns, these associations suggest that genetic adaptation to high altitude involves alteration in energy utilization pathways.

  4. A Complexity-Aware Video Adaptation Mechanism for Live Streaming Systems

    NASA Astrophysics Data System (ADS)

    Lu, Meng-Ting; Yao, Jason J.; Chen, Homer H.

    2007-12-01

    The paradigm shift of network design from performance-centric to constraint-centric has called for new signal processing techniques to deal with various aspects of resource-constrained communication and networking. In this paper, we consider the computational constraints of a multimedia communication system and propose a video adaptation mechanism for live video streaming of multiple channels. The video adaptation mechanism includes three salient features. First, it adjusts the computational resource of the streaming server block by block to provide a fine control of the encoding complexity. Second, as far as we know, it is the first mechanism to allocate the computational resource to multiple channels. Third, it utilizes a complexity-distortion model to determine the optimal coding parameter values to achieve global optimization. These techniques constitute the basic building blocks for a successful application of wireless and Internet video to digital home, surveillance, IPTV, and online games.

  5. Analysis of the Molecular Dialogue Between Gray Mold (Botrytis cinerea) and Grapevine (Vitis vinifera) Reveals a Clear Shift in Defense Mechanisms During Berry Ripening.

    PubMed

    Kelloniemi, Jani; Trouvelot, Sophie; Héloir, Marie-Claire; Simon, Adeline; Dalmais, Bérengère; Frettinger, Patrick; Cimerman, Agnès; Fermaud, Marc; Roudet, Jean; Baulande, Sylvain; Bruel, Christophe; Choquer, Mathias; Couvelard, Linhdavanh; Duthieuw, Mathilde; Ferrarini, Alberto; Flors, Victor; Le Pêcheur, Pascal; Loisel, Elise; Morgant, Guillaume; Poussereau, Nathalie; Pradier, Jean-Marc; Rascle, Christine; Trdá, Lucie; Poinssot, Benoit; Viaud, Muriel

    2015-11-01

    Mature grapevine berries at the harvesting stage (MB) are very susceptible to the gray mold fungus Botrytis cinerea, while veraison berries (VB) are not. We conducted simultaneous microscopic and transcriptomic analyses of the pathogen and the host to investigate the infection process developed by B. cinerea on MB versus VB, and the plant defense mechanisms deployed to stop the fungus spreading. On the pathogen side, our genome-wide transcriptomic data revealed that B. cinerea genes upregulated during infection of MB are enriched in functional categories related to necrotrophy, such as degradation of the plant cell wall, proteolysis, membrane transport, reactive oxygen species (ROS) generation, and detoxification. Quantitative-polymerase chain reaction on a set of representative genes related to virulence and microscopic observations further demonstrated that the infection is also initiated on VB but is stopped at the penetration stage. On the plant side, genome-wide transcriptomic analysis and metabolic data revealed a defense pathway switch during berry ripening. In response to B. cinerea inoculation, VB activated a burst of ROS, the salicylate-dependent defense pathway, the synthesis of the resveratrol phytoalexin, and cell-wall strengthening. On the contrary, in infected MB, the jasmonate-dependent pathway was activated, which did not stop the fungal necrotrophic process. PMID:26267356

  6. Analysis of the Molecular Dialogue Between Gray Mold (Botrytis cinerea) and Grapevine (Vitis vinifera) Reveals a Clear Shift in Defense Mechanisms During Berry Ripening.

    PubMed

    Kelloniemi, Jani; Trouvelot, Sophie; Héloir, Marie-Claire; Simon, Adeline; Dalmais, Bérengère; Frettinger, Patrick; Cimerman, Agnès; Fermaud, Marc; Roudet, Jean; Baulande, Sylvain; Bruel, Christophe; Choquer, Mathias; Couvelard, Linhdavanh; Duthieuw, Mathilde; Ferrarini, Alberto; Flors, Victor; Le Pêcheur, Pascal; Loisel, Elise; Morgant, Guillaume; Poussereau, Nathalie; Pradier, Jean-Marc; Rascle, Christine; Trdá, Lucie; Poinssot, Benoit; Viaud, Muriel

    2015-11-01

    Mature grapevine berries at the harvesting stage (MB) are very susceptible to the gray mold fungus Botrytis cinerea, while veraison berries (VB) are not. We conducted simultaneous microscopic and transcriptomic analyses of the pathogen and the host to investigate the infection process developed by B. cinerea on MB versus VB, and the plant defense mechanisms deployed to stop the fungus spreading. On the pathogen side, our genome-wide transcriptomic data revealed that B. cinerea genes upregulated during infection of MB are enriched in functional categories related to necrotrophy, such as degradation of the plant cell wall, proteolysis, membrane transport, reactive oxygen species (ROS) generation, and detoxification. Quantitative-polymerase chain reaction on a set of representative genes related to virulence and microscopic observations further demonstrated that the infection is also initiated on VB but is stopped at the penetration stage. On the plant side, genome-wide transcriptomic analysis and metabolic data revealed a defense pathway switch during berry ripening. In response to B. cinerea inoculation, VB activated a burst of ROS, the salicylate-dependent defense pathway, the synthesis of the resveratrol phytoalexin, and cell-wall strengthening. On the contrary, in infected MB, the jasmonate-dependent pathway was activated, which did not stop the fungal necrotrophic process.

  7. Molecular mechanisms for mitochondrial adaptation to exercise training in skeletal muscle.

    PubMed

    Drake, Joshua C; Wilson, Rebecca J; Yan, Zhen

    2016-01-01

    Exercise training enhances physical performance and confers health benefits, largely through adaptations in skeletal muscle. Mitochondrial adaptation, encompassing coordinated improvements in quantity (content) and quality (structure and function), is increasingly recognized as a key factor in the beneficial outcomes of exercise training. Exercise training has long been known to promote mitochondrial biogenesis, but recent work has demonstrated that it has a profound impact on mitochondrial dynamics (fusion and fission) and clearance (mitophagy), as well. In this review, we discuss the various mechanisms through which exercise training promotes mitochondrial quantity and quality in skeletal muscle.

  8. The Role of Adaptation in Body Load-Regulating Mechanisms During Locomotion

    NASA Technical Reports Server (NTRS)

    Ruttley, Tara; Holt, Christopher; Mulavara, Ajitkumar; Bloomberg, Jacob

    2010-01-01

    Body loading is a fundamental parameter that modulates motor output during locomotion, and is especially important for controlling the generation of stepping patterns, dynamic balance, and termination of locomotion. Load receptors that regulate and control posture and stance in locomotion include the Golgi tendon organs and muscle spindles at the hip, knee, and ankle joints, and the Ruffini endings and the Pacinian corpuscles in the soles of the feet. Increased body weight support (BWS) during locomotion results in an immediate reorganization of locomotor control, such as a reduction in stance and double support duration and decreased hip, ankle, and knee angles during the gait cycle. Previous studies on the effect during exposure to increased BWS while walking showed a reduction in lower limb joint angles and gait cycle timing that represents a reorganization of locomotor control. Until now, no studies have investigated how locomotor control responds after a period of exposure to adaptive modification in the body load sensing system. The goal of this research was to determine the adaptive properties of body load-regulating mechanisms in locomotor control during locomotion. We hypothesized that body load-regulating mechanisms contribute to locomotor control, and adaptive changes in these load-regulating mechanisms require reorganization to maintain forward locomotion. Head-torso coordination, lower limb movement patterns, and gait cycle timing were evaluated before and after a 30-minute adaptation session during which subjects walked on a treadmill at 5.4 km/hr with 40% body weight support (BWS). Before and after the adaptation period, head-torso and lower limb 3D kinematic data were obtained while performing a goal directed task during locomotion with 0% BWS using a video-based motion analysis system, and gait cycle timing parameters were collected by foot switches positioned under the heel and toe of the subjects shoes. Subjects showed adaptive modification in

  9. Cross-domain adaptation reveals that a common mechanism computes stereoscopic (cyclopean) and luminance plaid motion.

    PubMed

    Bowd, C; Donnelly, M; Shorter, S; Patterson, R

    2000-01-01

    Across three experiments, this study investigated the visual processing of moving stereoscopic plaid patterns (plaids created with cyclopean components defined by moving binocular disparity embedded in a dynamic random-dot stereogram). Results showed that adaptation to a moving stereoscopic plaid or its components affected the perceived coherence of a luminance test plaid, and vice versa. Cross-domain adaptation suggests that stereoscopic and luminance motion signals feed into a common pattern-motion mechanism, consistent with the idea that stereoscopic motion signals are computed early in the motion processing stream.

  10. Induction of DIMBOA accumulation and systemic defense responses as a mechanism of enhanced resistance of mycorrhizal corn (Zea mays L.) to sheath blight.

    PubMed

    Song, Yuan Yuan; Cao, Man; Xie, Li Jun; Liang, Xiao Ting; Zeng, Ren Sen; Su, Yi Juan; Huang, Jing Hua; Wang, Rui Long; Luo, Shi Ming

    2011-11-01

    Arbuscular mycorrhizas are the most important symbioses in terrestrial ecosystems and they enhance the plant defense against numerous soil-borne pathogenic fungi and nematodes. Two corn (Zea mays) varieties, Gaoyou-115 that is susceptible to sheath blight disease caused by Rhizoctonia solani and Yuenong-9 that is resistant, were used for mycorrhizal inoculation in this study. Pre-inoculation of susceptible Gaoyou-115 with arbuscular mycorrhizal fungus (AMF) Glomus mosseae significantly reduced the disease incidence and disease severity of sheath blight of corn. HPLC analysis showed that AMF inoculation led to significant increase in 2,4-dihydroxy-7-methoxy-2 H-1,4-benzoxazin-3(4 H)-one (DIMBOA) accumulation in the roots of both corn varieties and in leaves of resistant Yuenong-9. R. solani inoculation alone did not result in accumulation of DIMBOA in both roots and leaves of the two corn varieties. Our previous study showed that DIMBOA strongly inhibited mycelial growth of R. solani in vitro. Real-time PCR analysis showed that mycorrhizal inoculation itself did not affect the transcripts of most genes tested. However, pre-inoculation with G. mosseae induced strong responses of three defense-related genes PR2a, PAL, and AOS, as well as BX9, one of the key genes in DIMBOA biosynthesis pathway, in the leaves of corn plants of both Yuenong-9 and Gaoyou-115 after the pathogen attack. Induction of defense responses in pre-inoculated plants was much higher and quicker than that in non-inoculated plants upon R. solani infection. These results indicate that induction of accumulation of DIMBOA, an important phytoalexin in corn, and systemic defense responses by AMF, plays a vital role in enhanced disease resistance of mycorrhizal plants of corn against sheath blight. This study also suggests that priming is an important mechanism in mycorrhiza-induced resistance.

  11. D2 dopamine receptor-mediated mechanisms in the medial preoptic-anterior hypothalamus regulate effective defense behavior in the cat.

    PubMed

    Sweidan, S; Edinger, H; Siegel, A

    1991-05-17

    The role of the dopaminergic innervation of the medial preoptic-anterior hypothalamus (mPO-AH) in regulating the expression of affective defense behavior in the cat has been investigated in the present study. Feline affective defense behavior, characterized mainly by autonomic arousal, ear retraction, growling, hissing and paw striking, was elicited by electrical stimulation of the ventromedial hypothalamic nucleus (VMH). Following the establishment of a stable threshold current for eliciting the hissing response of the behavior, the effect of injecting various DAergic agonists and antagonists into the mPO-AH on the hissing threshold was determined. The microinjection of the non-selective DA agonist apomorphine (0.03, 0.16, 0.33, 0.66, 1.56 and 3.3 nmol) into the mPO-AH facilitated hissing in a time- and dose-dependent manner. This effect was mimicked by the D2-selective agonist LY 171555 (0.2 and 1.0 nmol) but not by the D1-selective agonist SKF 38393 (1.7 and 17 nmol), and was blocked by the non-selective and the D2-selective antagonists haloperidol (1.3 nmol) and sulpiride (14.5 nmol), respectively. The injection of the D1-selective antagonist SCH 23390 (0.3 nmol), however, did not inhibit apomorphine-induced facilitation of hissing. In addition, the injection of haloperidol (1.3 nmol) and sulpiride (14.5 nmol), but not SCH 23390 (0.3 nmol), alone inhibited the behavior. It was therefore concluded that dopaminergic stimulation of the mPO-AH may facilitate the expression of affective defense behavior in the cat via a D2 receptor-mediated mechanism. The physiological significance of this effect and the interaction between dopaminergic, noradrenergic and serotonergic innervation of the mPO-AH in modulating the expression of affective defense behavior in response to threatening stimuli are discussed. PMID:1680019

  12. Selection on defensive traits in a sterile caste - caste evolution: a mechanism to overcome life-history trade-offs?

    PubMed

    Roux, Estelle A; Roux, Maurice; Korb, Judith

    2009-01-01

    During development and evolution individuals generally face a trade-off between the development of weapons and gonads. In termites, characterized by reproductive division of labor, a caste evolved-the soldiers-which is completely sterile and which might be released from developmental trade-offs between weapons and testes. These soldiers are exclusively dedicated to defense. First, we investigated whether defensive traits are under selection in sterile termite soldiers using allometric analyses. In soldiers of the genus Cryptotermes phragmotic traits such as a sculptured and foreshortened head evolve rapidly but were also lost twice. Second, we compared the scaling relationships of these weapons with those in solitary insects facing a trade-off between weapons and gonads. Defensive traits consistently had lower slopes than nondefensive traits which supports the existence of stabilizing selection on soldier phragmotic traits in order to plug galleries. Moreover, soldier head widths were colony specific and correlated with the minimum gallery diameter of a colony. This can proximately be explained by soldiers developing from different instars. The scaling relationships of these termite soldiers contrast strikingly with those of weapons of solitary insects, which are generally exaggerated (i.e., overscaling) male traits. These differences may provide important insights into trait evolution. Trade-offs constraining the development of individuals may have been uncoupled in termites by evolving different castes, each specialized for one function. When individuals in social insect are "released" from developmental constraints through the evolution of castes, this certainly contributed to the ecological and evolutionary success of social insects.

  13. Adaptation of cardiac structure by mechanical feedback in the environment of the cell: a model study.

    PubMed Central

    Arts, T; Prinzen, F W; Snoeckx, L H; Rijcken, J M; Reneman, R S

    1994-01-01

    In the cardiac left ventricle during systole mechanical load of the myocardial fibers is distributed uniformly. A mechanism is proposed by which control of mechanical load is distributed over many individual control units acting in the environment of the cell. The mechanics of the equatorial region of the left ventricle was modeled by a thick-walled cylinder composed of 6-1500 shells of myocardial fiber material. In each shell a separate control unit was simulated. The direction of the cells was varied so that systolic fiber shortening approached a given optimum of 15%. End-diastolic sarcomere length was maintained at 2.1 microns. Regional early-systolic stretch and global contractility stimulated growth of cellular mass. If systolic shortening was more than normal the passive extracellular matrix stretched. The design of the load-controlling mechanism was derived from biological experiments showing that cellular processes are sensitive to mechanical deformation. After simulating a few hundred adaptation cycles, the macroscopic anatomical arrangement of helical pathways of the myocardial fibers formed automatically. If pump load of the ventricle was changed, wall thickness and cavity volume adapted physiologically. We propose that the cardiac anatomy may be defined and maintained by a multitude of control units for mechanical load, each acting in the cellular environment. Interestingly, feedback through fiber stress is not a compelling condition for such control. PMID:8038399

  14. Daylight Adaptive Shading Using Parametric Camshaft Mechanism for SOHO in Jakarta

    NASA Astrophysics Data System (ADS)

    Utama Sjarifudin, Firza; Justina, Laurensia

    2014-03-01

    This research analyzes SOHO (Small Office Home Office) which can adjust to the need of visual comfort for the users through natural daylighting and also can be adapted to standard requirements of 14 creative industry workspace in Jakartas. The method of the research is by simulating the SOHO unit with variation of shading opening angles in order to adapt to each unit. Analysis done to every shading opening angle to get the appropriate daylight intensity level which support the work activities in every unit for the whole day. In order for the shading to be able to adapt to the changing daylight condition, previously developed parametric camshaft mechanism was used. The study found that the visual comfort for SOHO with creative industries workers in Jakarta can be achieve by varying the shading opening angles between 15-75°.

  15. Terrain Adaptability Mechanism of Large Ruminants' Feet on the Kinematics View

    PubMed Central

    Zhang, Qun; Ding, Xilun; Xu, Kun

    2015-01-01

    Ruminants live in various parts of land. Similar cloven hooves assist ruminants in adapting to different ground environment during locomotion. This paper analyzes the general terrain adaptability of the feet of ruminants using kinematics of the equivalent mechanism model based on screw theory. Cloven hooves could adjust attitude by changing relative positions between two digits in swing phase. This function helps to choose better landing orientation. “Grasping” or “holding” a rock or other object on the ground passively provides extra adhesion force in stance phase. Ruminants could adjust the position of the metacarpophalangeal joint or metatarsophalangeal joint (MTP or MCP) with no relative motion between the tip of feet and the ground, which ensures the adhesion and dexterity in stance phase. These functions are derived from an example from chamois' feet and several assumptions, which are believed to demonstrate the foundation of adaptation of ruminants and ensure a stable and continuous movement. PMID:27019579

  16. Adaptive backstepping sliding mode control with fuzzy monitoring strategy for a kind of mechanical system.

    PubMed

    Song, Zhankui; Sun, Kaibiao

    2014-01-01

    A novel adaptive backstepping sliding mode control (ABSMC) law with fuzzy monitoring strategy is proposed for the tracking-control of a kind of nonlinear mechanical system. The proposed ABSMC scheme combining the sliding mode control and backstepping technique ensure that the occurrence of the sliding motion in finite-time and the trajectory of tracking-error converge to equilibrium point. To obtain a better perturbation rejection property, an adaptive control law is employed to compensate the lumped perturbation. Furthermore, we introduce fuzzy monitoring strategy to improve adaptive capacity and soften the control signal. The convergence and stability of the proposed control scheme are proved by using Lyaponov's method. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  17. Mechanics of pressure-adaptive honeycomb and its application to wing morphing

    NASA Astrophysics Data System (ADS)

    Vos, Roelof; Barrett, Ron

    2011-09-01

    Current, highly active classes of adaptive materials have been considered for use in many different aerospace applications. From adaptive flight control surfaces to wing surfaces, shape-memory alloy (SMA), piezoelectric and electrorheological fluids are making their way into wings, stabilizers and rotor blades. Despite the benefits which can be seen in many classes of aircraft, some profound challenges are ever present, including low power and energy density, high power consumption, high development and installation costs and outright programmatic blockages due to a lack of a materials certification database on FAR 23/25 and 27/29 certified aircraft. Three years ago, a class of adaptive structure was developed to skirt these daunting challenges. This pressure-adaptive honeycomb (PAH) is capable of extremely high performance and is FAA/EASA certifiable because it employs well characterized materials arranged in ways that lend a high level of adaptivity to the structure. This study is centered on laying out the mechanics, analytical models and experimental test data describing this new form of adaptive material. A directionally biased PAH system using an external (spring) force acting on the PAH bending structure was examined. The paper discusses the mechanics of pressure adaptive honeycomb and describes a simple reduced order model that can be used to simplify the geometric model in a finite element environment. The model assumes that a variable stiffness honeycomb results in an overall deformation of the honeycomb. Strains in excess of 50% can be generated through this mechanism without encountering local material (yield) limits. It was also shown that the energy density of pressure-adaptive honeycomb is akin to that of shape-memory alloy, while exhibiting strains that are an order of magnitude greater with an energy efficiency close to 100%. Excellent correlation between theory and experiment is demonstrated in a number of tests. A proof-of-concept wing section

  18. Fibrin Networks Support Recurring Mechanical Loads by Adapting their Structure across Multiple Scales.

    PubMed

    Kurniawan, Nicholas A; Vos, Bart E; Biebricher, Andreas; Wuite, Gijs J L; Peterman, Erwin J G; Koenderink, Gijsje H

    2016-09-01

    Tissues and cells sustain recurring mechanical loads that span a wide range of loading amplitudes and timescales as a consequence of exposure to blood flow, muscle activity, and external impact. Both tissues and cells derive their mechanical strength from fibrous protein scaffolds, which typically have a complex hierarchical structure. In this study, we focus on a prototypical hierarchical biomaterial, fibrin, which is one of the most resilient naturally occurring biopolymers and forms the structural scaffold of blood clots. We show how fibrous networks composed of fibrin utilize irreversible changes in their hierarchical structure at different scales to maintain reversible stress stiffening up to large strains. To trace the origin of this paradoxical resilience, we systematically tuned the microstructural parameters of fibrin and used a combination of optical tweezers and fluorescence microscopy to measure the interactions of single fibrin fibers for the first time, to our knowledge. We demonstrate that fibrin networks adapt to moderate strains by remodeling at the network scale through the spontaneous formation of new bonds between fibers, whereas they adapt to high strains by plastic remodeling of the fibers themselves. This multiscale adaptation mechanism endows fibrin gels with the remarkable ability to sustain recurring loads due to shear flows and wound stretching. Our findings therefore reveal a microscopic mechanism by which tissues and cells can balance elastic nonlinearity and plasticity, and thus can provide microstructural insights into cell-driven remodeling of tissues. PMID:27602730

  19. The dynamics of the Π1 colour mechanism: further evidence for two sites of adaptation

    PubMed Central

    Augenstein, E. J.; Pugh, E. N.

    1977-01-01

    1. The visual pathway that determines Stiles's Π1 colour mechanism was isolated by the auxiliary field technique and studied under dynamic conditions of light adaptation and recovery by threshold measurements. 2. The time courses of adaptation to Π1-equated short wave-length (μ ≤ 500 nm) and long wave-length (μ ≥ 550 nm) fields are very distinct: a large and relatively long-enduring transient threshold elevation occurs at the onset of the long wave-length, but not of the short wave-length fields. 3. Similarly, the time courses of recovery from Π1-equated long and short wave-length fields are quite distinctive: a large and relatively long enduring transient (`transient tritanopia') occurs at the offset of the long wave-length, but not of the short wave-length fields. 4. The wave-lengths of the fields which cause the adaptation transients coincide with those shown previously (Pugh, 1976) to combine non-additively with μ = 430 nm fields in effecting Π1 adaptation. The failure of the time course of Π1 adaptation to be spectrally `univariant' combines with the failures of field-additivity to demonstrate that signals from the long and/or middle wave-length sensitive cones affect the adaptation state of the Π1 pathway. 5. The adaptation transients are not observed in the pathways that determine Π4 and Π5. Thus, instantaneous signals from the middle and/or long wave-length sensitive cones are not the cause of the transients. Rather the cause must lie in the path by which those cones transmit their signals to the Π1 pathway or in the Π1 pathway itself. 6. The off-transient can be diminished by adding an adequately intense short wave-length field to a long wave-length field that would normally cause it. The Π1 pathway must receive chromatically opponent signals. PMID:592192

  20. Functional Genomic Insights into Regulatory Mechanisms of High-Altitude Adaptation.

    PubMed

    Storz, Jay F; Cheviron, Zachary A

    2016-01-01

    Recent studies of indigenous human populations at high altitude have provided proof-of-principle that genome scans of DNA polymorphism can be used to identify candidate loci for hypoxia adaptation. When integrated with experimental analyses of physiological phenotypes, genome-wide surveys of DNA polymorphism and tissue-specific transcriptional profiles can provide insights into actual mechanisms of adaptation. It has been suggested that adaptive phenotypic evolution is largely mediated by cis-regulatory changes in genes that are located at integrative control points in regulatory networks. This hypothesis can be tested by conducting transcriptomic analyses of hypoxic signaling pathways in conjunction with experimental measures of vascular oxygen supply and metabolic pathway flux. Such studies may reveal whether the architecture of gene regulatory networks can be used to predict which loci (and which types of loci) are likely to be "hot spots" for adaptive physiological evolution. Functional genomic studies of deer mice (Peromyscus maniculatus) demonstrate how the integrated analysis of variation in tissue-specific transcriptomes, whole-animal physiological performance, and various subordinate traits can yield insights into the mechanistic underpinnings of high-altitude adaptation. PMID:27343092

  1. Mechanical Strain Causes Adaptive Change in Bronchial Fibroblasts Enhancing Profibrotic and Inflammatory Responses

    PubMed Central

    Manuyakorn, Wiparat; Smart, David E.; Noto, Antonio; Bucchieri, Fabio; Haitchi, Hans Michael; Holgate, Stephen T.; Howarth, Peter H.; Davies, Donna E.

    2016-01-01

    Asthma is characterized by periodic episodes of bronchoconstriction and reversible airway obstruction; these symptoms are attributable to a number of factors including increased mass and reactivity of bronchial smooth muscle and extracellular matrix (ECM) in asthmatic airways. Literature has suggested changes in cell responses and signaling can be elicited via modulation of mechanical stress acting upon them, potentially affecting the microenvironment of the cell. In this study, we hypothesized that mechanical strain directly affects the (myo)fibroblast phenotype in asthma. Therefore, we characterized responses of bronchial fibroblasts, from 6 normal and 11 asthmatic non-smoking volunteers, exposed to cyclical mechanical strain using flexible silastic membranes. Samples were analyzed for proteoglycans, α-smooth muscle actin (αSMA), collagens I and III, matrix metalloproteinase (MMP) 2 & 9 and interleukin-8 (IL-8) by qRT-PCR, Western blot, zymography and ELISA. Mechanical strain caused a decrease in αSMA mRNA but no change in either αSMA protein or proteoglycan expression. In contrast the inflammatory mediator IL-8, MMPs and interstitial collagens were increased at both the transcriptional and protein level. The results demonstrate an adaptive response of bronchial fibroblasts to mechanical strain, irrespective of donor. The adaptation involves cytoskeletal rearrangement, matrix remodelling and inflammatory cytokine release. These results suggest that mechanical strain could contribute to disease progression in asthma by promoting inflammation and remodelling responses. PMID:27101406

  2. Adaptation of an industrial application for an instructional laboratory in mechanical vibrations

    SciTech Connect

    Whiteman, W.E. )

    1990-01-01

    Extensive theoretical treatment is given to damping as the process of energy dissipation during mechanical vibration. The challenge in the classroom is to adequately convey this concept and extend it by teaching students practical applications in engineering analysis and design. Students are motivated by real-world problems; applying these types of problems with strong instructional classroom content significantly enhances the learning environment. This paper proposes the adaptation of an actual research project to a simple, yet innovative, mechanical vibrations laboratory. The adapted project involves an ongoing effort at the Los Alamos National Laboratory to investigate damping factors of various alloys used in military tank munitions. The kinetic-energy penetrators used in these tank rounds are cylindrical in shape and are a major class of weapons designed to defeat heavy armor. Unwanted transverse oscillations of these penetrators degrade the accuracy of the rounds and may lead to glancing blows off the target. 5 refs., 3 figs.

  3. Rule-based mechanisms of learning for intelligent adaptive flight control

    NASA Technical Reports Server (NTRS)

    Handelman, David A.; Stengel, Robert F.

    1990-01-01

    How certain aspects of human learning can be used to characterize learning in intelligent adaptive control systems is investigated. Reflexive and declarative memory and learning are described. It is shown that model-based systems-theoretic adaptive control methods exhibit attributes of reflexive learning, whereas the problem-solving capabilities of knowledge-based systems of artificial intelligence are naturally suited for implementing declarative learning. Issues related to learning in knowledge-based control systems are addressed, with particular attention given to rule-based systems. A mechanism for real-time rule-based knowledge acquisition is suggested, and utilization of this mechanism within the context of failure diagnosis for fault-tolerant flight control is demonstrated.

  4. Preferential Osmolyte Accumulation: a Mechanism of Osmotic Stress Adaptation in Diazotrophic Bacteria

    PubMed Central

    Madkour, Magdy A.; Smith, Linda Tombras; Smith, Gary M.

    1990-01-01

    A common cellular mechanism of osmotic-stress adaptation is the intracellular accumulation of organic solutes (osmolytes). We investigated the mechanism of osmotic adaptation in the diazotrophic bacteria Azotobacter chroococcum, Azospirillum brasilense, and Klebsiella pneumoniae, which are adversely affected by high osmotic strength (i.e., soil salinity and/or drought). We used natural-abundance 13C nuclear magnetic resonance spectroscopy to identify all the osmolytes accumulating in these strains during osmotic stress generated by 0.5 M NaCl. Evidence is presented for the accumulation of trehalose and glutamate in Azotobacter chroococcum ZSM4, proline and glutamate in Azospirillum brasilense SHS6, and trehalose and proline in K. pneumoniae. Glycine betaine was accumulated in all strains grown in culture media containing yeast extract as the sole nitrogen source. Alternative nitrogen sources (e.g., NH4Cl or casamino acids) in the culture medium did not result in measurable glycine betaine accumulation. We suggest that the mechanism of osmotic adaptation in these organisms entails the accumulation of osmolytes in hyperosmotically stressed cells resulting from either enhanced uptake from the medium (of glycine betaine, proline, and glutamate) or increased net biosynthesis (of trehalose, proline, and glutamate) or both. The preferred osmolyte in Azotobacter chroococcum ZSM4 shifted from glutamate to trehalose as a consequence of a prolonged osmotic stress. Also, the dominant osmolyte in Azospirillum brasilense SHS6 shifted from glutamate to proline accumulation as the osmotic strength of the medium increased. PMID:16348295

  5. Strategies for adding adaptive learning mechanisms to rule-based diagnostic expert systems

    NASA Technical Reports Server (NTRS)

    Stclair, D. C.; Sabharwal, C. L.; Bond, W. E.; Hacke, Keith

    1988-01-01

    Rule-based diagnostic expert systems can be used to perform many of the diagnostic chores necessary in today's complex space systems. These expert systems typically take a set of symptoms as input and produce diagnostic advice as output. The primary objective of such expert systems is to provide accurate and comprehensive advice which can be used to help return the space system in question to nominal operation. The development and maintenance of diagnostic expert systems is time and labor intensive since the services of both knowledge engineer(s) and domain expert(s) are required. The use of adaptive learning mechanisms to increment evaluate and refine rules promises to reduce both time and labor costs associated with such systems. This paper describes the basic adaptive learning mechanisms of strengthening, weakening, generalization, discrimination, and discovery. Next basic strategies are discussed for adding these learning mechanisms to rule-based diagnostic expert systems. These strategies support the incremental evaluation and refinement of rules in the knowledge base by comparing the set of advice given by the expert system (A) with the correct diagnosis (C). Techniques are described for selecting those rules in the in the knowledge base which should participate in adaptive learning. The strategies presented may be used with a wide variety of learning algorithms. Further, these strategies are applicable to a large number of rule-based diagnostic expert systems. They may be used to provide either immediate or deferred updating of the knowledge base.

  6. An epidemic spreading model on adaptive scale-free networks with feedback mechanism

    NASA Astrophysics Data System (ADS)

    Li, Tao; Liu, Xiongding; Wu, Jie; Wan, Chen; Guan, Zhi-Hong; Wang, Yuanmei

    2016-05-01

    A SIRS epidemic model with feedback mechanism on adaptive scale-free networks is presented. Using the mean field theory the spreading dynamics of the epidemic is studied in detail. The basic reproductive number and equilibriums are derived. Theoretical results indicate that the basic reproductive number is significantly dependent on the topology of the underlying networks. The existence of equilibriums is determined by the basic reproductive number. The global stability of disease-free equilibrium and the epidemic permanence are proved in detail. The feedback mechanism cannot change the basic reproductive number, but it can reduce the endemic level and weaken the epidemic spreading. Numerical simulations confirmed the analytical results.

  7. Mechanisms of Host Receptor Adaptation by Severe Acute Respiratory Syndrome Coronavirus

    SciTech Connect

    Wu, Kailang; Peng, Guiqing; Wilken, Matthew; Geraghty, Robert J.; Li, Fang

    2012-12-10

    The severe acute respiratory syndrome coronavirus (SARS-CoV) from palm civets has twice evolved the capacity to infect humans by gaining binding affinity for human receptor angiotensin-converting enzyme 2 (ACE2). Numerous mutations have been identified in the receptor-binding domain (RBD) of different SARS-CoV strains isolated from humans or civets. Why these mutations were naturally selected or how SARS-CoV evolved to adapt to different host receptors has been poorly understood, presenting evolutionary and epidemic conundrums. In this study, we investigated the impact of these mutations on receptor recognition, an important determinant of SARS-CoV infection and pathogenesis. Using a combination of biochemical, functional, and crystallographic approaches, we elucidated the molecular and structural mechanisms of each of these naturally selected RBD mutations. These mutations either strengthen favorable interactions or reduce unfavorable interactions with two virus-binding hot spots on ACE2, and by doing so, they enhance viral interactions with either human (hACE2) or civet (cACE2) ACE2. Therefore, these mutations were viral adaptations to either hACE2 or cACE2. To corroborate the above analysis, we designed and characterized two optimized RBDs. The human-optimized RBD contains all of the hACE2-adapted residues (Phe-442, Phe-472, Asn-479, Asp-480, and Thr-487) and possesses exceptionally high affinity for hACE2 but relative low affinity for cACE2. The civet-optimized RBD contains all of the cACE2-adapted residues (Tyr-442, Pro-472, Arg-479, Gly-480, and Thr-487) and possesses exceptionally high affinity for cACE2 and also substantial affinity for hACE2. These results not only illustrate the detailed mechanisms of host receptor adaptation by SARS-CoV but also provide a molecular and structural basis for tracking future SARS-CoV evolution in animals.

  8. Antipredator defenses predict diversification rates

    PubMed Central

    Arbuckle, Kevin; Speed, Michael P.

    2015-01-01

    The “escape-and-radiate” hypothesis predicts that antipredator defenses facilitate adaptive radiations by enabling escape from constraints of predation, diversified habitat use, and subsequently speciation. Animals have evolved diverse strategies to reduce the direct costs of predation, including cryptic coloration and behavior, chemical defenses, mimicry, and advertisement of unprofitability (conspicuous warning coloration). Whereas the survival consequences of these alternative defenses for individuals are well-studied, little attention has been given to the macroevolutionary consequences of alternative forms of defense. Here we show, using amphibians as the first, to our knowledge, large-scale empirical test in animals, that there are important macroevolutionary consequences of alternative defenses. However, the escape-and-radiate hypothesis does not adequately describe them, due to its exclusive focus on speciation. We examined how rates of speciation and extinction vary across defensive traits throughout amphibians. Lineages that use chemical defenses show higher rates of speciation as predicted by escape-and-radiate but also show higher rates of extinction compared with those without chemical defense. The effect of chemical defense is a net reduction in diversification compared with lineages without chemical defense. In contrast, acquisition of conspicuous coloration (often used as warning signals or in mimicry) is associated with heightened speciation rates but unchanged extinction rates. We conclude that predictions based on the escape-and-radiate hypothesis must incorporate the effect of traits on both speciation and extinction, which is rarely considered in such studies. Our results also suggest that knowledge of defensive traits could have a bearing on the predictability of extinction, perhaps especially important in globally threatened taxa such as amphibians. PMID:26483488

  9. Gene duplication as a mechanism of genomic adaptation to a changing environment

    PubMed Central

    Kondrashov, Fyodor A.

    2012-01-01

    A subject of extensive study in evolutionary theory has been the issue of how neutral, redundant copies can be maintained in the genome for long periods of time. Concurrently, examples of adaptive gene duplications to various environmental conditions in different species have been described. At this point, it is too early to tell whether or not a substantial fraction of gene copies have initially achieved fixation by positive selection for increased dosage. Nevertheless, enough examples have accumulated in the literature that such a possibility should be considered. Here, I review the recent examples of adaptive gene duplications and make an attempt to draw generalizations on what types of genes may be particularly prone to be selected for under certain environmental conditions. The identification of copy-number variation in ecological field studies of species adapting to stressful or novel environmental conditions may improve our understanding of gene duplications as a mechanism of adaptation and its relevance to the long-term persistence of gene duplications. PMID:22977152

  10. The adaptation of the cerebral circulation to pregnancy: mechanisms and consequences

    PubMed Central

    Cipolla, Marilyn J

    2013-01-01

    The adaptation of the cerebral circulation to pregnancy is unique from other vascular beds. Most notably, the growth and vasodilatory response to high levels of circulating growth factors and cytokines that promote substantial hemodynamic changes in other vascular beds is limited in the cerebral circulation. This is accomplished through several mechanisms, including downregulation of key receptors and transcription factors, and production of circulating factors that counteract the vasodilatory effects of vascular endothelial growth factor (VEGF) and placental growth factor. Pregnancy both prevents and reverses hypertensive inward remodeling of cerebral arteries, possibly through downregulation of the angiotensin type 1 receptor. The blood–brain barrier (BBB) importantly adapts to pregnancy by preventing the passage of seizure provoking serum into the brain and limiting the permeability effects of VEGF that is more highly expressed in cerebral vasculature during pregnancy. While the adaptation of the cerebral circulation to pregnancy provides for relatively normal cerebral blood flow and BBB properties in the face of substantial cardiovascular changes and high levels of circulating factors, under pathologic conditions, these adaptations appear to promote greater brain injury, including edema formation during acute hypertension, and greater sensitivity to bacterial endotoxin. PMID:23321787

  11. Environmentally-controlled microtensile testing of mechanically-adaptive polymer nanocomposites for ex vivo characterization.

    PubMed

    Hess, Allison E; Potter, Kelsey A; Tyler, Dustin J; Zorman, Christian A; Capadona, Jeffrey R

    2013-08-20

    Implantable microdevices are gaining significant attention for several biomedical applications. Such devices have been made from a range of materials, each offering its own advantages and shortcomings. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control. To this end, a custom microtensile tester was designed to accommodate microscale samples with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation. The overall goal of this method is to quantitatively assess the in vivo mechanical

  12. Design of a knee joint mechanism that adapts to individual physiology.

    PubMed

    Jiun-Yih Kuan; Pasch, Kenneth A; Herr, Hugh M

    2014-01-01

    This paper describes the design of a new knee joint mechanism, called the Adaptive Coupling Joint (ACJ). The new mechanism has an adaptive trajectory of the center of rotations (COR) that automatically matches those of the attached biological joint. The detailed design is presented as well as characterization results of the ACJ. Conventional exoskeleton and assistive devices usually consider limb joints as a one to three degrees of freedom (DOFs) joint synthesized by multiple one-DOF hinge joints in a single plane. However, the biological joints are complex and usually rotate with respect to a changing COR. As a result, the mismatch between limb joint motion and mechanical interface motion can lead to forces that cause undesired ligament and muscle length changes and internal mechanical changes. These undesired changes contribute to discomfort, as well as to the slippage and sluggish interaction between humans and devices. It is shown that the ACJ can transmit planetary torques from either active or passive devices to the limbs without altering the normal biological joint motion. PMID:25570389

  13. Design of a knee joint mechanism that adapts to individual physiology.

    PubMed

    Jiun-Yih Kuan; Pasch, Kenneth A; Herr, Hugh M

    2014-01-01

    This paper describes the design of a new knee joint mechanism, called the Adaptive Coupling Joint (ACJ). The new mechanism has an adaptive trajectory of the center of rotations (COR) that automatically matches those of the attached biological joint. The detailed design is presented as well as characterization results of the ACJ. Conventional exoskeleton and assistive devices usually consider limb joints as a one to three degrees of freedom (DOFs) joint synthesized by multiple one-DOF hinge joints in a single plane. However, the biological joints are complex and usually rotate with respect to a changing COR. As a result, the mismatch between limb joint motion and mechanical interface motion can lead to forces that cause undesired ligament and muscle length changes and internal mechanical changes. These undesired changes contribute to discomfort, as well as to the slippage and sluggish interaction between humans and devices. It is shown that the ACJ can transmit planetary torques from either active or passive devices to the limbs without altering the normal biological joint motion.

  14. Tissue mechanics govern the rapidly adapting and symmetrical response to touch.

    PubMed

    Eastwood, Amy L; Sanzeni, Alessandro; Petzold, Bryan C; Park, Sung-Jin; Vergassola, Massimo; Pruitt, Beth L; Goodman, Miriam B

    2015-12-15

    Interactions with the physical world are deeply rooted in our sense of touch and depend on ensembles of somatosensory neurons that invade and innervate the skin. Somatosensory neurons convert the mechanical energy delivered in each touch into excitatory membrane currents carried by mechanoelectrical transduction (MeT) channels. Pacinian corpuscles in mammals and touch receptor neurons (TRNs) in Caenorhabditis elegans nematodes are embedded in distinctive specialized accessory structures, have low thresholds for activation, and adapt rapidly to the application and removal of mechanical loads. Recently, many of the protein partners that form native MeT channels in these and other somatosensory neurons have been identified. However, the biophysical mechanism of symmetric responses to the onset and offset of mechanical stimulation has eluded understanding for decades. Moreover, it is not known whether applied force or the resulting indentation activate MeT channels. Here, we introduce a system for simultaneously recording membrane current, applied force, and the resulting indentation in living C. elegans (Feedback-controlled Application of mechanical Loads Combined with in vivo Neurophysiology, FALCON) and use it, together with modeling, to study these questions. We show that current amplitude increases with indentation, not force, and that fast stimuli evoke larger currents than slower stimuli producing the same or smaller indentation. A model linking body indentation to MeT channel activation through an embedded viscoelastic element reproduces the experimental findings, predicts that the TRNs function as a band-pass mechanical filter, and provides a general mechanism for symmetrical and rapidly adapting MeT channel activation relevant to somatosensory neurons across phyla and submodalities.

  15. Tissue mechanics govern the rapidly adapting and symmetrical response to touch

    PubMed Central

    Eastwood, Amy L.; Sanzeni, Alessandro; Petzold, Bryan C.; Park, Sung-Jin; Vergassola, Massimo; Pruitt, Beth L.

    2015-01-01

    Interactions with the physical world are deeply rooted in our sense of touch and depend on ensembles of somatosensory neurons that invade and innervate the skin. Somatosensory neurons convert the mechanical energy delivered in each touch into excitatory membrane currents carried by mechanoelectrical transduction (MeT) channels. Pacinian corpuscles in mammals and touch receptor neurons (TRNs) in Caenorhabditis elegans nematodes are embedded in distinctive specialized accessory structures, have low thresholds for activation, and adapt rapidly to the application and removal of mechanical loads. Recently, many of the protein partners that form native MeT channels in these and other somatosensory neurons have been identified. However, the biophysical mechanism of symmetric responses to the onset and offset of mechanical stimulation has eluded understanding for decades. Moreover, it is not known whether applied force or the resulting indentation activate MeT channels. Here, we introduce a system for simultaneously recording membrane current, applied force, and the resulting indentation in living C. elegans (Feedback-controlled Application of mechanical Loads Combined with in vivo Neurophysiology, FALCON) and use it, together with modeling, to study these questions. We show that current amplitude increases with indentation, not force, and that fast stimuli evoke larger currents than slower stimuli producing the same or smaller indentation. A model linking body indentation to MeT channel activation through an embedded viscoelastic element reproduces the experimental findings, predicts that the TRNs function as a band-pass mechanical filter, and provides a general mechanism for symmetrical and rapidly adapting MeT channel activation relevant to somatosensory neurons across phyla and submodalities. PMID:26627717

  16. Genomic and transcriptomic analysis of NDM-1 Klebsiella pneumoniae in spaceflight reveal mechanisms underlying environmental adaptability.

    PubMed

    Li, Jia; Liu, Fei; Wang, Qi; Ge, Pupu; Woo, Patrick C Y; Yan, Jinghua; Zhao, Yanlin; Gao, George F; Liu, Cui Hua; Liu, Changting

    2014-01-01

    The emergence and rapid spread of New Delhi Metallo-beta-lactamase-1 (NDM-1)-producing Klebsiella pneumoniae strains has caused a great concern worldwide. To better understand the mechanisms underlying environmental adaptation of those highly drug-resistant K. pneumoniae strains, we took advantage of the China's Shenzhou 10 spacecraft mission to conduct comparative genomic and transcriptomic analysis of a NDM-1 K. pneumoniae strain (ATCC BAA-2146) being cultivated under different conditions. The samples were recovered from semisolid medium placed on the ground (D strain), in simulated space condition (M strain), or in Shenzhou 10 spacecraft (T strain) for analysis. Our data revealed multiple variations underlying pathogen adaptation into different environments in terms of changes in morphology, H2O2 tolerance and biofilm formation ability, genomic stability and regulation of metabolic pathways. Additionally, we found a few non-coding RNAs to be differentially regulated. The results are helpful for better understanding the adaptive mechanisms of drug-resistant bacterial pathogens. PMID:25163721

  17. Genomic and transcriptomic analysis of NDM-1 Klebsiella pneumoniae in spaceflight reveal mechanisms underlying environmental adaptability

    PubMed Central

    Li, Jia; Liu, Fei; Wang, Qi; Ge, Pupu; Woo, Patrick C. Y.; Yan, Jinghua; Zhao, Yanlin; Gao, George F.; Liu, Cui Hua; Liu, Changting

    2014-01-01

    The emergence and rapid spread of New Delhi Metallo-beta-lactamase-1 (NDM-1)-producing Klebsiella pneumoniae strains has caused a great concern worldwide. To better understand the mechanisms underlying environmental adaptation of those highly drug-resistant K. pneumoniae strains, we took advantage of the China's Shenzhou 10 spacecraft mission to conduct comparative genomic and transcriptomic analysis of a NDM-1 K. pneumoniae strain (ATCC BAA-2146) being cultivated under different conditions. The samples were recovered from semisolid medium placed on the ground (D strain), in simulated space condition (M strain), or in Shenzhou 10 spacecraft (T strain) for analysis. Our data revealed multiple variations underlying pathogen adaptation into different environments in terms of changes in morphology, H2O2 tolerance and biofilm formation ability, genomic stability and regulation of metabolic pathways. Additionally, we found a few non-coding RNAs to be differentially regulated. The results are helpful for better understanding the adaptive mechanisms of drug-resistant bacterial pathogens. PMID:25163721

  18. Cultural variation in Africa: role of mechanisms of transmission and adaptation.

    PubMed Central

    Guglielmino, C R; Viganotti, C; Hewlett, B; Cavalli-Sforza, L L

    1995-01-01

    Cultural inheritance can be considered as a mechanism of adaptation made possible by communication, which has reached its greatest development in humans and can allow long-term conservation or rapid change of culturally transmissible traits depending on circumstances and needs. Conservativeness/flexibility is largely modulated by mechanisms of sociocultural transmission. An analysis was carried out by testing the fit of three models to 47 cultural traits (classified in six groups) in 277 African societies. Model A (demic diffusion) is conservation over generations, as shown by correlations of cultural traits with language, used as a measure of historical connection. Model B (environmental adaptation) is measured by correlation to the natural environment. Model C (cultural diffusion) is the spread to neighbors by social contact in an epidemic-like fashion and was tested by measuring the tightness of geographic clustering of the traits. Most traits examined, in particular those affecting family structure and kinship, showed great conservation over generations, as shown by the fit of model A. They are most probably transmitted by family members. This is in agreement with the theoretical demonstration that cultural transmission in the family (vertical) is the most conservative one. Some traits show environmental effects, indicating the importance of adaptation to physical environment. Only a few of the 47 traits showed tight geographic clustering indicating that their spread to nearest neighbors follows model C, as is usually the case for transmission among unrelated people (called horizontal transmission). PMID:11607569

  19. Evolution of plant growth and defense in a continental introduction.

    PubMed

    Agrawal, Anurag A; Hastings, Amy P; Bradburd, Gideon S; Woods, Ellen C; Züst, Tobias; Harvey, Jeffrey A; Bukovinszky, Tibor

    2015-07-01

    Substantial research has addressed adaptation of nonnative biota to novel environments, yet surprisingly little work has integrated population genetic structure and the mechanisms underlying phenotypic differentiation in ecologically important traits. We report on studies of the common milkweed Asclepias syriaca, which was introduced from North America to Europe over the past 400 years and which lacks most of its specialized herbivores in the introduced range. Using 10 populations from each continent grown in a common environment, we identified several growth and defense traits that have diverged, despite low neutral genetic differentiation between continents. We next developed a Bayesian modeling approach to account for relationships between molecular and phenotypic differences, confirming that continental trait differentiation was greater than expected from neutral genetic differentiation. We found evidence that growth-related traits adaptively diverged within and between continents. Inducible defenses triggered by monarch butterfly herbivory were substantially reduced in European populations, and this reduction in inducibility was concordant with altered phytohormonal dynamics, reduced plant growth, and a trade-off with constitutive investment. Freedom from the community of native and specialized herbivores may have favored constitutive over induced defense. Our replicated analysis of plant growth and defense, including phenotypically plastic traits, suggests adaptive evolution following a continental introduction. PMID:26098351

  20. Current understanding of grapevine defense mechanisms against the biotrophic fungus (Erysiphe necator), the causal agent of powdery mildew disease.

    PubMed

    Qiu, Wenping; Feechan, Angela; Dry, Ian

    2015-01-01

    The most economically important disease of cultivated grapevines worldwide is powdery mildew (PM) caused by the ascomycete fungus Erysiphe necator. The majority of grapevine cultivars used for wine, table grape, and dried fruit production are derived from the Eurasian grape species Vitis vinifera because of its superior aroma and flavor characteristics. However, this species has little genetic resistance against E. necator meaning that grape production is highly dependent on the frequent use of fungicides. The integration of effective genetic resistance into cultivated grapevines would lead to significant financial and environmental benefits and represents a major challenge for viticultural industries and researchers worldwide. This review will outline the strategies being used to increase our understanding of the molecular basis of V. vinifera susceptibility to this fungal pathogen. It will summarize our current knowledge of different resistance loci/genes that have evolved in wild grapevine species to restrict PM infection and assess the potential application of these defense genes in the generation of PM-resistant grapevine germplasm. Finally, it addresses future research priorities which will be important in the rapid identification, evaluation, and deployment of new PM resistance genes which are capable of conferring effective and durable resistance in the vineyard. PMID:26504571

  1. Disentangling Detoxification: Gene Expression Analysis of Feeding Mountain Pine Beetle Illuminates Molecular-Level Host Chemical Defense Detoxification Mechanisms

    PubMed Central

    Robert, Jeanne A.; Pitt, Caitlin; Bonnett, Tiffany R.; Yuen, Macaire M. S.; Keeling, Christopher I.; Bohlmann, Jörg; Huber, Dezene P. W.

    2013-01-01

    The mountain pine beetle, Dendroctonus ponderosae, is a native species of bark beetle (Coleoptera: Curculionidae) that caused unprecedented damage to the pine forests of British Columbia and other parts of western North America and is currently expanding its range into the boreal forests of central and eastern Canada and the USA. We conducted a large-scale gene expression analysis (RNA-seq) of mountain pine beetle male and female adults either starved or fed in male-female pairs for 24 hours on lodgepole pine host tree tissues. Our aim was to uncover transcripts involved in coniferophagous mountain pine beetle detoxification systems during early host colonization. Transcripts of members from several gene families significantly increased in insects fed on host tissue including: cytochromes P450, glucosyl transferases and glutathione S-transferases, esterases, and one ABC transporter. Other significantly increasing transcripts with potential roles in detoxification of host defenses included alcohol dehydrogenases and a group of unexpected transcripts whose products may play an, as yet, undiscovered role in host colonization by mountain pine beetle. PMID:24223726

  2. Evolution of plant defense mechanisms. Relationships of phenylcoumaran benzylic ether reductases to pinoresinol-lariciresinol and isoflavone reductases.

    PubMed

    Gang, D R; Kasahara, H; Xia, Z Q; Vander Mijnsbrugge, K; Bauw, G; Boerjan, W; Van Montagu, M; Davin, L B; Lewis, N G

    1999-03-12

    Pinoresinol-lariciresinol and isoflavone reductase classes are phylogenetically related, as is a third, the so-called "isoflavone reductase homologs." This study establishes the first known catalytic function for the latter, as being able to engender the NADPH-dependent reduction of phenylcoumaran benzylic ethers. Accordingly, all three reductase classes are involved in the biosynthesis of important and related phenylpropanoid-derived plant defense compounds. In this investigation, the phenylcoumaran benzylic ether reductase from the gymnosperm, Pinus taeda, was cloned, with the recombinant protein heterologously expressed in Escherichia coli. The purified enzyme reduces the benzylic ether functionalities of both dehydrodiconiferyl alcohol and dihydrodehydrodiconiferyl alcohol, with a higher affinity for the former, as measured by apparent Km and Vmax values and observed kinetic 3H-isotope effects. It abstracts the 4R-hydride of the required NADPH cofactor in a manner analogous to that of the pinoresinol-lariciresinol reductases and isoflavone reductases. A similar catalytic function was observed for the corresponding recombinant reductase whose gene was cloned from the angiosperm, Populus trichocarpa. Interestingly, both pinoresinol-lariciresinol reductases and isoflavone reductases catalyze enantiospecific conversions, whereas the phenylcoumaran benzylic ether reductase only shows regiospecific discrimination. A possible evolutionary relationship among the three reductase classes is proposed, based on the supposition that phenylcoumaran benzylic ether reductases represent the progenitors of pinoresinol-lariciresinol and isoflavone reductases.

  3. Disentangling detoxification: gene expression analysis of feeding mountain pine beetle illuminates molecular-level host chemical defense detoxification mechanisms.

    PubMed

    Robert, Jeanne A; Pitt, Caitlin; Bonnett, Tiffany R; Yuen, Macaire M S; Keeling, Christopher I; Bohlmann, Jörg; Huber, Dezene P W

    2013-01-01

    The mountain pine beetle, Dendroctonus ponderosae, is a native species of bark beetle (Coleoptera: Curculionidae) that caused unprecedented damage to the pine forests of British Columbia and other parts of western North America and is currently expanding its range into the boreal forests of central and eastern Canada and the USA. We conducted a large-scale gene expression analysis (RNA-seq) of mountain pine beetle male and female adults either starved or fed in male-female pairs for 24 hours on lodgepole pine host tree tissues. Our aim was to uncover transcripts involved in coniferophagous mountain pine beetle detoxification systems during early host colonization. Transcripts of members from several gene families significantly increased in insects fed on host tissue including: cytochromes P450, glucosyl transferases and glutathione S-transferases, esterases, and one ABC transporter. Other significantly increasing transcripts with potential roles in detoxification of host defenses included alcohol dehydrogenases and a group of unexpected transcripts whose products may play an, as yet, undiscovered role in host colonization by mountain pine beetle.

  4. Current understanding of grapevine defense mechanisms against the biotrophic fungus (Erysiphe necator), the causal agent of powdery mildew disease

    PubMed Central

    Qiu, Wenping; Feechan, Angela; Dry, Ian

    2015-01-01

    The most economically important disease of cultivated grapevines worldwide is powdery mildew (PM) caused by the ascomycete fungus Erysiphe necator. The majority of grapevine cultivars used for wine, table grape, and dried fruit production are derived from the Eurasian grape species Vitis vinifera because of its superior aroma and flavor characteristics. However, this species has little genetic resistance against E. necator meaning that grape production is highly dependent on the frequent use of fungicides. The integration of effective genetic resistance into cultivated grapevines would lead to significant financial and environmental benefits and represents a major challenge for viticultural industries and researchers worldwide. This review will outline the strategies being used to increase our understanding of the molecular basis of V. vinifera susceptibility to this fungal pathogen. It will summarize our current knowledge of different resistance loci/genes that have evolved in wild grapevine species to restrict PM infection and assess the potential application of these defense genes in the generation of PM-resistant grapevine germplasm. Finally, it addresses future research priorities which will be important in the rapid identification, evaluation, and deployment of new PM resistance genes which are capable of conferring effective and durable resistance in the vineyard. PMID:26504571

  5. Molecular Adaptation Mechanisms Employed by Ethanologenic Bacteria in Response to Lignocellulose-derived Inhibitory Compounds

    PubMed Central

    Ibraheem, Omodele; Ndimba, Bongani K.

    2013-01-01

    Current international interest in finding alternative sources of energy to the diminishing supplies of fossil fuels has encouraged research efforts in improving biofuel production technologies. In countries which lack sufficient food, the use of sustainable lignocellulosic feedstocks, for the production of bioethanol, is an attractive option. In the pre-treatment of lignocellulosic feedstocks for ethanol production, various chemicals and/or enzymatic processes are employed. These methods generally result in a range of fermentable sugars, which are subjected to microbial fermentation and distillation to produce bioethanol. However, these methods also produce compounds that are inhibitory to the microbial fermentation process. These compounds include products of sugar dehydration and lignin depolymerisation, such as organic acids, derivatised furaldehydes and phenolic acids. These compounds are known to have a severe negative impact on the ethanologenic microorganisms involved in the fermentation process by compromising the integrity of their cell membranes, inhibiting essential enzymes and negatively interact with their DNA/RNA. It is therefore important to understand the molecular mechanisms of these inhibitions, and the mechanisms by which these microorganisms show increased adaptation to such inhibitors. Presented here is a concise overview of the molecular adaptation mechanisms of ethanologenic bacteria in response to lignocellulose-derived inhibitory compounds. These include general stress response and tolerance mechanisms, which are typically those that maintain intracellular pH homeostasis and cell membrane integrity, activation/regulation of global stress responses and inhibitor substrate-specific degradation pathways. We anticipate that understanding these adaptation responses will be essential in the design of 'intelligent' metabolic engineering strategies for the generation of hyper-tolerant fermentation bacteria strains. PMID:23847442

  6. Molecular adaptation mechanisms employed by ethanologenic bacteria in response to lignocellulose-derived inhibitory compounds.

    PubMed

    Ibraheem, Omodele; Ndimba, Bongani K

    2013-01-01

    Current international interest in finding alternative sources of energy to the diminishing supplies of fossil fuels has encouraged research efforts in improving biofuel production technologies. In countries which lack sufficient food, the use of sustainable lignocellulosic feedstocks, for the production of bioethanol, is an attractive option. In the pre-treatment of lignocellulosic feedstocks for ethanol production, various chemicals and/or enzymatic processes are employed. These methods generally result in a range of fermentable sugars, which are subjected to microbial fermentation and distillation to produce bioethanol. However, these methods also produce compounds that are inhibitory to the microbial fermentation process. These compounds include products of sugar dehydration and lignin depolymerisation, such as organic acids, derivatised furaldehydes and phenolic acids. These compounds are known to have a severe negative impact on the ethanologenic microorganisms involved in the fermentation process by compromising the integrity of their cell membranes, inhibiting essential enzymes and negatively interact with their DNA/RNA. It is therefore important to understand the molecular mechanisms of these inhibitions, and the mechanisms by which these microorganisms show increased adaptation to such inhibitors. Presented here is a concise overview of the molecular adaptation mechanisms of ethanologenic bacteria in response to lignocellulose-derived inhibitory compounds. These include general stress response and tolerance mechanisms, which are typically those that maintain intracellular pH homeostasis and cell membrane integrity, activation/regulation of global stress responses and inhibitor substrate-specific degradation pathways. We anticipate that understanding these adaptation responses will be essential in the design of 'intelligent' metabolic engineering strategies for the generation of hyper-tolerant fermentation bacteria strains. PMID:23847442

  7. L-ALLIANCE: a mechanism for adaptive action selection in heterogeneous multi-robot teams

    SciTech Connect

    Parker, L.E.

    1995-11-01

    In practical applications of robotics, it is usually quite difficult, if not impossible, for the system designer to fully predict the environmental states in which the robots will operate. The complexity of the problem is further increased when dealing with teams of robots which themselves may be incompletely known and characterized in advance. It is thus highly desirable for robot teams to be able to adapt their performance during the mission due to changes in the environment, or to changes in other robot team members. In previous work, we introduced a behavior-based mechanism called the ALLIANCE architecture -- that facilitates the fault tolerant cooperative control of multi-robot teams. However, this previous work did not address the issue of how to dynamically update the control parameters during a mission to adapt to ongoing changes in the environment or in the robot team, and to ensure the efficiency of the collective team actions. In this paper, we address this issue by proposing the L-ALLIANCE mechanism, which defines an automated method whereby robots can use knowledge learned from previous experience to continually improve their collective action selection when working on missions composed of loosely coupled, discrete subtasks. This ability to dynamically update robotic control parameters provides a number of distinct advantages: it alleviates the need for human tuning of control parameters, it facilitates the use of custom-designed multi-robot teams for any given application, it improves the efficiency of the mission performance, and It allows robots to continually adapt their performance over time due to changes in the robot team and/or the environment. We describe the L-ALLIANCE mechanism, present the results of various alternative update strategies we investigated, present the formal model of the L-ALLIANCE mechanism, and present the results of a simple proof of concept implementation on a small team of heterogeneous mobile robots.

  8. Origin and Functional Diversification of an Amphibian Defense Peptide Arsenal

    PubMed Central

    Roelants, Kim; Fry, Bryan G.; Ye, Lumeng; Stijlemans, Benoit; Brys, Lea; Kok, Philippe; Clynen, Elke; Schoofs, Liliane; Cornelis, Pierre; Bossuyt, Franky

    2013-01-01

    The skin secretion of many amphibians contains an arsenal of bioactive molecules, including hormone-like peptides (HLPs) acting as defense toxins against predators, and antimicrobial peptides (AMPs) providing protection against infectious microorganisms. Several amphibian taxa seem to have independently acquired the genes to produce skin-secreted peptide arsenals, but it remains unknown how these originated from a non-defensive ancestral gene and evolved diverse defense functions against predators and pathogens. We conducted transcriptome, genome, peptidome and phylogenetic analyses to chart the full gene repertoire underlying the defense peptide arsenal of the frog Silurana tropicalis and reconstruct its evolutionary history. Our study uncovers a cluster of 13 transcriptionally active genes, together encoding up to 19 peptides, including diverse HLP homologues and AMPs. This gene cluster arose from a duplicated gastrointestinal hormone gene that attained a HLP-like defense function after major remodeling of its promoter region. Instead, new defense functions, including antimicrobial activity, arose by mutation of the precursor proteins, resulting in the proteolytic processing of secondary peptides alongside the original ones. Although gene duplication did not trigger functional innovation, it may have subsequently facilitated the convergent loss of the original function in multiple gene lineages (subfunctionalization), completing their transformation from HLP gene to AMP gene. The processing of multiple peptides from a single precursor entails a mechanism through which peptide-encoding genes may establish new functions without the need for gene duplication to avoid adaptive conflicts with older ones. PMID:23935531

  9. COMET-AR User's Manual: COmputational MEchanics Testbed with Adaptive Refinement

    NASA Technical Reports Server (NTRS)

    Moas, E. (Editor)

    1997-01-01

    The COMET-AR User's Manual provides a reference manual for the Computational Structural Mechanics Testbed with Adaptive Refinement (COMET-AR), a software system developed jointly by Lockheed Palo Alto Research Laboratory and NASA Langley Research Center under contract NAS1-18444. The COMET-AR system is an extended version of an earlier finite element based structural analysis system called COMET, also developed by Lockheed and NASA. The primary extensions are the adaptive mesh refinement capabilities and a new "object-like" database interface that makes COMET-AR easier to extend further. This User's Manual provides a detailed description of the user interface to COMET-AR from the viewpoint of a structural analyst.

  10. Behavioral and neural Darwinism: selectionist function and mechanism in adaptive behavior dynamics.

    PubMed

    McDowell, J J

    2010-05-01

    An evolutionary theory of behavior dynamics and a theory of neuronal group selection share a common selectionist framework. The theory of behavior dynamics instantiates abstractly the idea that behavior is selected by its consequences. It implements Darwinian principles of selection, reproduction, and mutation to generate adaptive behavior in virtual organisms. The behavior generated by the theory has been shown to be quantitatively indistinguishable from that of live organisms. The theory of neuronal group selection suggests a mechanism whereby the abstract principles of the evolutionary theory may be implemented in the nervous systems of biological organisms. According to this theory, groups of neurons subserving behavior may be selected by synaptic modifications that occur when the consequences of behavior activate value systems in the brain. Together, these theories constitute a framework for a comprehensive account of adaptive behavior that extends from brain function to the behavior of whole organisms in quantitative detail.

  11. Protective effect of butyrate against ethanol-induced gastric ulcers in mice by promoting the anti-inflammatory, anti-oxidant and mucosal defense mechanisms.

    PubMed

    Liu, Jiaming; Wang, Fangyan; Luo, Haihua; Liu, Aihua; Li, Kangxin; Li, Cui; Jiang, Yong

    2016-01-01

    Gastric ulcers (GUs) are a common type of peptic ulcer. Alcohol overdose is one of the main causes of GU, which is difficult to prevent. Although the protective effect of butyrate on inflammation-related diseases is well understood, its effect on GUs has not been reported. We investigated the protective effects of butyrate against ethanol-induced lesions to the gastric mucosa in mice and the underlying mechanisms. BALB/c mice were orally pretreated with butyrate for 30min prior to the establishment of the GU model by challenge with absolute ethanol. Ethanol administration produced apparent mucosal injuries with morphological and histological damage, whereas butyrate pretreatment reduced the gastric mucosal injuries in a dose-dependent manner. Butyrate pretreatment also significantly ameliorated contents of malondialdehyde (MDA) and carbonyl proteins, and decreased levels of IL-1β, TNF-α and IL-6. The Western blot results consistently demonstrated that butyrate pretreatment attenuated the phosphorylation of NF-κB p65, p38 MAPK and ERKs in the gastric tissues. Additionally, gastric wall mucus (GWM), a parameter reflecting mucosal defense, was clearly increased by butyrate pretreatment. Butyrate pretreatment protects the gastric mucosa against ethanol-induced lesions by strengthening the mucosal defense and anti-oxidant and anti-inflammatory activities. As a necessary substance for the body, butyrate may be applied to the prevention and treatment of GUs.

  12. Ornithine and Homocitrulline Impair Mitochondrial Function, Decrease Antioxidant Defenses and Induce Cell Death in Menadione-Stressed Rat Cortical Astrocytes: Potential Mechanisms of Neurological Dysfunction in HHH Syndrome.

    PubMed

    Zanatta, Ângela; Rodrigues, Marília Danyelle Nunes; Amaral, Alexandre Umpierrez; Souza, Débora Guerini; Quincozes-Santos, André; Wajner, Moacir

    2016-09-01

    Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is caused by deficiency of ornithine translocase leading to predominant tissue accumulation and high urinary excretion of ornithine (Orn), homocitrulline (Hcit) and ammonia. Although affected patients commonly present neurological dysfunction manifested by cognitive deficit, spastic paraplegia, pyramidal and extrapyramidal signs, stroke-like episodes, hypotonia and ataxia, its pathogenesis is still poorly known. Although astrocytes are necessary for neuronal protection. Therefore, in the present study we investigated the effects of Orn and Hcit on cell viability (propidium iodide incorporation), mitochondrial function (thiazolyl blue tetrazolium bromide-MTT-reduction and mitochondrial membrane potential-ΔΨm), antioxidant defenses (GSH) and pro-inflammatory response (NFkB, IL-1β, IL-6 and TNF-α) in unstimulated and menadione-stressed cortical astrocytes that were previously shown to be susceptible to damage by neurotoxins. We first observed that Orn decreased MTT reduction, whereas both amino acids decreased GSH levels, without altering cell viability and the pro-inflammatory factors in unstimulated astrocytes. Furthermore, Orn and Hcit decreased cell viability and ΔΨm in menadione-treated astrocytes. The present data indicate that the major compounds accumulating in HHH syndrome impair mitochondrial function and reduce cell viability and the antioxidant defenses in cultured astrocytes especially when stressed by menadione. It is presumed that these mechanisms may be involved in the neuropathology of this disease. PMID:27161368

  13. Ornithine and Homocitrulline Impair Mitochondrial Function, Decrease Antioxidant Defenses and Induce Cell Death in Menadione-Stressed Rat Cortical Astrocytes: Potential Mechanisms of Neurological Dysfunction in HHH Syndrome.

    PubMed

    Zanatta, Ângela; Rodrigues, Marília Danyelle Nunes; Amaral, Alexandre Umpierrez; Souza, Débora Guerini; Quincozes-Santos, André; Wajner, Moacir

    2016-09-01

    Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is caused by deficiency of ornithine translocase leading to predominant tissue accumulation and high urinary excretion of ornithine (Orn), homocitrulline (Hcit) and ammonia. Although affected patients commonly present neurological dysfunction manifested by cognitive deficit, spastic paraplegia, pyramidal and extrapyramidal signs, stroke-like episodes, hypotonia and ataxia, its pathogenesis is still poorly known. Although astrocytes are necessary for neuronal protection. Therefore, in the present study we investigated the effects of Orn and Hcit on cell viability (propidium iodide incorporation), mitochondrial function (thiazolyl blue tetrazolium bromide-MTT-reduction and mitochondrial membrane potential-ΔΨm), antioxidant defenses (GSH) and pro-inflammatory response (NFkB, IL-1β, IL-6 and TNF-α) in unstimulated and menadione-stressed cortical astrocytes that were previously shown to be susceptible to damage by neurotoxins. We first observed that Orn decreased MTT reduction, whereas both amino acids decreased GSH levels, without altering cell viability and the pro-inflammatory factors in unstimulated astrocytes. Furthermore, Orn and Hcit decreased cell viability and ΔΨm in menadione-treated astrocytes. The present data indicate that the major compounds accumulating in HHH syndrome impair mitochondrial function and reduce cell viability and the antioxidant defenses in cultured astrocytes especially when stressed by menadione. It is presumed that these mechanisms may be involved in the neuropathology of this disease.

  14. Molecular cloning of the tomato Hairless gene implicates actin dynamics in trichome-mediated defense and mechanical properties of stem tissue

    PubMed Central

    Kang, Jin-Ho; Campos, Marcelo L.; Zemelis-Durfee, Starla; Al-Haddad, Jameel M.; Jones, A. Daniel; Telewski, Frank W.; Brandizzi, Federica; Howe, Gregg A.

    2016-01-01

    Trichomes are epidermal structures that provide a first line of defense against arthropod herbivores. The recessive hairless (hl) mutation in tomato (Solanum lycopersicum L.) causes severe distortion of trichomes on all aerial tissues, impairs the accumulation of sesquiterpene and polyphenolic compounds in glandular trichomes, and compromises resistance to the specialist herbivore Manduca sexta. Here, we demonstrate that the tomato Hl gene encodes a subunit (SRA1) of the highly conserved WAVE regulatory complex that controls nucleation of actin filaments in a wide range of eukaryotic cells. The tomato SRA1 gene spans a 42-kb region containing both Solyc11g013280 and Solyc11g013290. The hl mutation corresponds to a complex 3-kb deletion that removes the last exon of the gene. Expression of a wild-type SRA1 cDNA in the hl mutant background restored normal trichome development, accumulation of glandular trichome-derived metabolites, and resistance to insect herbivory. These findings establish a role for SRA1 in the development of tomato trichomes and also implicate the actin-cytoskeleton network in cytosolic control of specialized metabolism for plant defense. We also show that the brittleness of hl mutant stems is associated with altered mechanical and cell morphological properties of stem tissue, and demonstrate that this defect is directly linked to the mutation in SRA1. PMID:27481446

  15. Lessons in Fundamental Mechanisms and Diverse Adaptations from the 2015 Bacterial Locomotion and Signal Transduction Meeting

    PubMed Central

    Prüβ, Birgit M.; Liu, Jun; Higgs, Penelope I.

    2015-01-01

    In response to rapid changes in their environment, bacteria control a number of processes, including motility, cell division, biofilm formation, and virulence. Research presented in January 2015 at the biennial Bacterial Locomotion and Signal Transduction (BLAST) meeting in Tucson, AZ, illustrates the elegant complexity of the nanoarrays, nanomachines, and networks of interacting proteins that mediate such processes. Studies employing an array of biophysical, genetic, cell biology, and mathematical methods are providing an increasingly detailed understanding of the mechanisms of these systems within well-studied bacteria. Furthermore, comparisons of these processes in diverse bacterial species are providing insight into novel regulatory and functional mechanisms. This review summarizes research presented at the BLAST meeting on these fundamental mechanisms and diverse adaptations, including findings of importance for applications involving bacteria of medical or agricultural relevance. PMID:26195592

  16. Fine-scale temporal adaptation within a salmonid population: mechanism and consequences.

    PubMed

    Gharrett, Anthony J; Joyce, John; Smoker, William W

    2013-09-01

    We demonstrate a clear example of local adaptation of seasonal timing of spawning and embryo development. The consequence is a population of pink salmon that is segmented into spawning groups that use the same limited habitat. We synthesize published observations with results of new analyses to demonstrate that genetic variation of these traits results in survival differentials related to that variation, and that density-dependent embryo mortality and seasonally variable juvenile mortality are a mechanism of selection. Most examples of local adaptation in natural systems depend on observed correlations between environments and fitness traits, but do not fully demonstrate local adaptation: that the trait is genetically determined, exhibits different fitness in common environments or across different environments, and its variation is mechanistically connected to fitness differences. The geographic or temporal scales of local adaptation often remain obscure. Here, we show that heritable, fine-scale differences of timing of reproductive migration in a pink salmon (Oncorhynchus gorbuscha) resulted in temporal structure that persisted several generations; the differences enable a density-dependent population to pack more spawners into limited spawning habitat, that is, enhance its fitness. A balanced trade-off of survivals results because embryos from early-migrating fish have a lower freshwater survival (harsh early physical conditions and disturbance by late spawners), but emigrant fry from late-migrating fish have lower marine survivals (timing of their vernal emergence into the estuarine environment). Such fine-scale local adaptations increase the genetic portfolio of the populations and may provide a buffer against the impacts of climate change.

  17. The Interplay Between Strategic And Adaptive Control Mechanisms In Plastic Recalibration Of Locomotor Function

    NASA Technical Reports Server (NTRS)

    Richards, J. T.; Mulavara, A. P.; Bloomberg, J. J.

    2006-01-01

    We have previously shown that viewing simulated rotary self-motion during treadmill locomotion causes immediate strategic modifications (Richards et al. 2004) as well as an after effect reflecting adaptive modification of the control of position and trajectory during over-ground locomotion (Mulavara et al. 2005). The process of sensorimotor adaptation is comprised of both strategic and adaptive control mechanisms. Strategic control involves cognitive, on-line corrections to limb movements once one is aware of a sensory discordance. Over an extended period of exposure to the sensory discordance, new strategic sensorimotor coordination patterns are reinforced until they become more automatic, and therefore adaptive, in nature. The objective of this study was to investigate how strategic changes in trunk control during exposure to simulated rotary self-motion during treadmill walking influences adaptive modification of locomotor heading direction during over-ground stepping. Subjects (n = 10) walked on a motorized linear treadmill while viewing a wide field-of-view virtual scene for 24 minutes. The scene was static for the first 4 minutes and then, for the last 20 minutes, depicted constant rate self-motion equivalent to walking in a counter-clockwise, circular path around the perimeter of a room. Subjects performed five stepping trials both before and after the exposure period to assess after effects. Results from our previous study showed a significant change in heading direction (HD) during post-exposure step tests that was opposite the direction in which the scene rotated during the adaptation period. For the present study, we quantified strategic modifications in trunk movement control during scene exposure using normalized root mean square (R(sub p)) variation of the subject's 3D trunk positions and normalized sum of standard deviations (R(sub o)) variation of 3D trunk orientations during scene rotation relative to that during static scene presentation

  18. Natural History of Innate Host Defense Peptides.

    PubMed

    Linde, A; Wachter, B; Höner, O P; Dib, L; Ross, C; Tamayo, A R; Blecha, F; Melgarejo, T

    2009-12-01

    Host defense peptides act on the forefront of innate immunity, thus playing a central role in the survival of animals and plants. Despite vast morphological changes in species through evolutionary history, all animals examined to date share common features in their innate immune defense strategies, hereunder expression of host defense peptides (HDPs). Most studies on HDPs have focused on humans, domestic and laboratory animals. More than a thousand different sequences have been identified, yet data on HDPs in wild-living animals are sparse. The biological functions of HDPs include broad-spectrum antimicrobial activity and immunomodulation. Natural selection and coevolutionary host-pathogen arms race theory suggest that the extent and specificity of the microbial load influences the spectrum and potency of HDPs in different species. Individuals of extant species-that have lived for an extended period in evolutionary history amid populations with intact processes of natural selection-likely possess the most powerful and well-adapted "natural antibiotics". Research on the evolutionary history of the innate defense system and the host in context of the consequences of challenges as well as the efficacy of the innate immune system under natural conditions is therefore of immediate interest. This review focuses on evolutionary aspects of immunophysiology, with emphasis on innate effector molecules. Studies on host defense in wild-living animals may significantly enhance our understanding of inborn immune mechanisms, and help identify molecules that may assist us to cope better with the increasing microbial challenges that likely follow from the continuous amplification of biodiversity levels on Earth. PMID:26783164

  19. Multiple symbiont acquisition strategies as an adaptive mechanism in the coral Stylophora pistillata.

    PubMed

    Byler, Kristen A; Carmi-Veal, Maya; Fine, Maoz; Goulet, Tamar L

    2013-01-01

    In obligate symbioses, the host's survival relies on the successful acquisition and maintenance of symbionts. Symbionts can either be transferred from parent to offspring via direct inheritance (vertical transmission) or acquired anew each generation from the environment (horizontal transmission). With vertical symbiont transmission, progeny benefit by not having to search for their obligate symbionts, and, with symbiont inheritance, a mechanism exists for perpetuating advantageous symbionts. But, if the progeny encounter an environment that differs from that of their parent, they may be disadvantaged if the inherited symbionts prove suboptimal. Conversely, while in horizontal symbiont acquisition host survival hinges on an unpredictable symbiont source, an individual host may acquire genetically diverse symbionts well suited to any given environment. In horizontal acquisition, however, a potentially advantageous symbiont will not be transmitted to subsequent generations. Adaptation in obligate symbioses may require mechanisms for both novel symbiont acquisition and symbiont inheritance. Using denaturing-gradient gel electrophoresis and real-time PCR, we identified the dinoflagellate symbionts (genus Symbiodinium) hosted by the Red Sea coral Stylophora pistillata throughout its ontogenesis and over depth. We present evidence that S. pistillata juvenile colonies may utilize both vertical and horizontal symbiont acquisition strategies. By releasing progeny with maternally derived symbionts, that are also capable of subsequent horizontal symbiont acquisition, coral colonies may acquire physiologically advantageous novel symbionts that are then perpetuated via vertical transmission to subsequent generations. With symbiont inheritance, natural selection can act upon the symbiotic variability, providing a mechanism for coral adaptation.

  20. The estimated mechanical advantage of the prosimian ankle joint musculature, and implications for locomotor adaptation.

    PubMed

    Goto, Ryosuke; Kumakura, Hiroo

    2013-05-01

    In this study we compared the power arm lengths and mechanical advantages attributed to 12 lower leg muscles across three prosimian species. The origins and insertions of the lower leg muscles in Garnett's galago, the ring-tailed lemur, and the slow loris were quantified and correlated with positional behaviour. The ankle joint of the galago has a speed-oriented mechanical system, in contrast to that of the slow loris, which exhibits more power-oriented mechanics. The lemur ankle joint exhibited intermediate power arm lengths and an intermediate mechanical advantage relative to the other primates. This result suggests that the mechanical differences in the ankle between the galago and the lemur, taxa that exhibit similar locomotory repertoires, reflect a difference in the kinematics and kinetics of leaping (i.e. generalised vs. specialised leapers). In contrast to leaping primates, lorises have developed a more power-oriented mechanical system as a foot adaptation for positional behaviours such as bridging or cantilevering in their arboreal habitat. PMID:23489408

  1. The estimated mechanical advantage of the prosimian ankle joint musculature, and implications for locomotor adaptation.

    PubMed

    Goto, Ryosuke; Kumakura, Hiroo

    2013-05-01

    In this study we compared the power arm lengths and mechanical advantages attributed to 12 lower leg muscles across three prosimian species. The origins and insertions of the lower leg muscles in Garnett's galago, the ring-tailed lemur, and the slow loris were quantified and correlated with positional behaviour. The ankle joint of the galago has a speed-oriented mechanical system, in contrast to that of the slow loris, which exhibits more power-oriented mechanics. The lemur ankle joint exhibited intermediate power arm lengths and an intermediate mechanical advantage relative to the other primates. This result suggests that the mechanical differences in the ankle between the galago and the lemur, taxa that exhibit similar locomotory repertoires, reflect a difference in the kinematics and kinetics of leaping (i.e. generalised vs. specialised leapers). In contrast to leaping primates, lorises have developed a more power-oriented mechanical system as a foot adaptation for positional behaviours such as bridging or cantilevering in their arboreal habitat.

  2. Mechanisms of Regulation of Olfactory Transduction and Adaptation in the Olfactory Cilium

    PubMed Central

    Antunes, Gabriela; Sebastião, Ana Maria; Simoes de Souza, Fabio Marques

    2014-01-01

    Olfactory adaptation is a fundamental process for the functioning of the olfactory system, but the underlying mechanisms regulating its occurrence in intact olfactory sensory neurons (OSNs) are not fully understood. In this work, we have combined stochastic computational modeling and a systematic pharmacological study of different signaling pathways to investigate their impact during short-term adaptation (STA). We used odorant stimulation and electroolfactogram (EOG) recordings of the olfactory epithelium treated with pharmacological blockers to study the molecular mechanisms regulating the occurrence of adaptation in OSNs. EOG responses to paired-pulses of odorants showed that inhibition of phosphodiesterases (PDEs) and phosphatases enhanced the levels of STA in the olfactory epithelium, and this effect was mimicked by blocking vesicle exocytosis and reduced by blocking cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) and vesicle endocytosis. These results suggest that G-coupled receptors (GPCRs) cycling is involved with the occurrence of STA. To gain insights on the dynamical aspects of this process, we developed a stochastic computational model. The model consists of the olfactory transduction currents mediated by the cyclic nucleotide gated (CNG) channels and calcium ion (Ca2+)-activated chloride (CAC) channels, and the dynamics of their respective ligands, cAMP and Ca2+, and it simulates the EOG results obtained under different experimental conditions through changes in the amplitude and duration of cAMP and Ca2+ response, two second messengers implicated with STA occurrence. The model reproduced the experimental data for each pharmacological treatment and provided a mechanistic explanation for the action of GPCR cycling in the levels of second messengers modulating the levels of STA. All together, these experimental and theoretical results indicate the existence of a mechanism of regulation of STA by signaling pathways that control GPCR

  3. The Contribution of Experimental in vivo Models to Understanding the Mechanisms of Adaptation to Mechanical Loading in Bone

    PubMed Central

    Meakin, Lee B.; Price, Joanna S.; Lanyon, Lance E.

    2014-01-01

    Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading. Jiri Hert introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gages to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced. Experiments combining strain gage instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats, and mice has yielded significant insight into the control of strain-related adaptive (re)modeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice, which is now the model of choice for many studies. Together such studies have demonstrated that over the physiological strain range, bone’s mechanically adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles, and that these are most effective when interrupted by short periods of rest between them

  4. Electro-Mechanical Manipulator for Use in the Remote Equipment Decontamination Cell at the Defense Waste Processing Facility, Savannah River Site - 12454

    SciTech Connect

    Lambrecht, Bill; Dixon, Joe; Neuville, John R.

    2012-07-01

    One of the legacies of the cold war is millions of liters of radioactive waste. One of the locations where this waste is stored is at the Savannah River Site (SRS) in South Carolina. A major effort to clean up this waste is on-going at the defense waste processing facility (DWPF) at SRS. A piece of this effort is decontamination of the equipment used in the DWPF to process the waste. The remote equipment decontamination cell (REDC) in the DWPF uses electro-mechanical manipulators (EMM) arms manufactured and supplied by PaR Systems to decontaminate DWPF process equipment. The decontamination fluid creates a highly corrosive environment. After 25 years of operational use the original EMM arms are aging and need replacement. To support continued operation of the DWPF, two direct replacement EMM arms were delivered to the REDC in the summer of 2011. (authors)

  5. Hybrid numerical method with adaptive overlapping meshes for solving nonstationary problems in continuum mechanics

    NASA Astrophysics Data System (ADS)

    Burago, N. G.; Nikitin, I. S.; Yakushev, V. L.

    2016-06-01

    Techniques that improve the accuracy of numerical solutions and reduce their computational costs are discussed as applied to continuum mechanics problems with complex time-varying geometry. The approach combines shock-capturing computations with the following methods: (1) overlapping meshes for specifying complex geometry; (2) elastic arbitrarily moving adaptive meshes for minimizing the approximation errors near shock waves, boundary layers, contact discontinuities, and moving boundaries; (3) matrix-free implementation of efficient iterative and explicit-implicit finite element schemes; (4) balancing viscosity (version of the stabilized Petrov-Galerkin method); (5) exponential adjustment of physical viscosity coefficients; and (6) stepwise correction of solutions for providing their monotonicity and conservativeness.

  6. Neurobiological mechanisms of adaptative plasticity. A possible contribution to cybernetic studies.

    PubMed

    Giaquinto, S

    1990-10-01

    Cybernetics can take advantages of future development in the field of Plasticity. The adaptative abilities of the nervous tissue, which is capable to modify its own functional organization and cope with pathological events, are triggered by communication within a network carrying memorized variations in the functional activity of the system induced by external inputs. Plasticity is served by anatomical modifications, as well as by neurophysiological processes. Regeneration, reactive synaptogenesis, functional reorganization, redundancy, equipotentiality are discussed. Some of these mechanisms are still unclear in the human and probably far-fetched. Personal EEG contribution argues against redundancy and equipotentiality. PMID:2082721

  7. Matrix Metalloproteinases in a Sea Urchin Ligament with Adaptable Mechanical Properties

    PubMed Central

    Ribeiro, Ana R.; Barbaglio, Alice; Oliveira, Maria J.; Ribeiro, Cristina C.; Wilkie, Iain C.; Candia Carnevali, Maria D.; Barbosa, Mário A.

    2012-01-01

    Mutable collagenous tissues (MCTs) of echinoderms show reversible changes in tensile properties (mutability) that are initiated and modulated by the nervous system via the activities of cells known as juxtaligamental cells. The molecular mechanism underpinning this mechanical adaptability has still to be elucidated. Adaptable connective tissues are also present in mammals, most notably in the uterine cervix, in which changes in stiffness result partly from changes in the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). There have been no attempts to assess the potential involvement of MMPs in the echinoderm mutability phenomenon, apart from studies dealing with a process whose relationship to the latter is uncertain. In this investigation we used the compass depressor ligaments (CDLs) of the sea-urchin Paracentrotus lividus. The effect of a synthetic MMP inhibitor - galardin - on the biomechanical properties of CDLs in different mechanical states (“standard”, “compliant” and “stiff”) was evaluated by dynamic mechanical analysis, and the presence of MMPs in normal and galardin-treated CDLs was determined semi-quantitatively by gelatin zymography. Galardin reversibly increased the stiffness and storage modulus of CDLs in all three states, although its effect was significantly lower in stiff than in standard or compliant CDLs. Gelatin zymography revealed a progressive increase in total gelatinolytic activity between the compliant, standard and stiff states, which was possibly due primarily to higher molecular weight components resulting from the inhibition and degradation of MMPs. Galardin caused no change in the gelatinolytic activity of stiff CDLs, a pronounced and statistically significant reduction in that of standard CDLs, and a pronounced, but not statistically significant, reduction in that of compliant CDLs. Our results provide evidence that MMPs may contribute to the variable tensility of the

  8. Epigenetic Control of Defense Signaling and Priming in Plants.

    PubMed

    Espinas, Nino A; Saze, Hidetoshi; Saijo, Yusuke

    2016-01-01

    Immune recognition of pathogen-associated molecular patterns or effectors leads to defense activation at the pathogen challenged sites. This is followed by systemic defense activation at distant non-challenged sites, termed systemic acquired resistance (SAR). These inducible defenses are accompanied by extensive transcriptional reprogramming of defense-related genes. SAR is associated with priming, in which a subset of these genes is kept at a poised state to facilitate subsequent transcriptional regulation. Transgenerational inheritance of defense-related priming in plants indicates the stability of such primed states. Recent studies have revealed the importance and dynamic engagement of epigenetic mechanisms, such as DNA methylation and histone modifications that are closely linked to chromatin reconfiguration, in plant adaptation to different biotic stresses. Herein we review current knowledge regarding the biological significance and underlying mechanisms of epigenetic control for immune responses in plants. We also argue for the importance of host transposable elements as critical regulators of interactions in the evolutionary "arms race" between plants and pathogens. PMID:27563304

  9. Epigenetic Control of Defense Signaling and Priming in Plants

    PubMed Central

    Espinas, Nino A.; Saze, Hidetoshi; Saijo, Yusuke

    2016-01-01

    Immune recognition of pathogen-associated molecular patterns or effectors leads to defense activation at the pathogen challenged sites. This is followed by systemic defense activation at distant non-challenged sites, termed systemic acquired resistance (SAR). These inducible defenses are accompanied by extensive transcriptional reprogramming of defense-related genes. SAR is associated with priming, in which a subset of these genes is kept at a poised state to facilitate subsequent transcriptional regulation. Transgenerational inheritance of defense-related priming in plants indicates the stability of such primed states. Recent studies have revealed the importance and dynamic engagement of epigenetic mechanisms, such as DNA methylation and histone modifications that are closely linked to chromatin reconfiguration, in plant adaptation to different biotic stresses. Herein we review current knowledge regarding the biological significance and underlying mechanisms of epigenetic control for immune responses in plants. We also argue for the importance of host transposable elements as critical regulators of interactions in the evolutionary “arms race” between plants and pathogens. PMID:27563304

  10. Induction of Nrf2-mediated cellular defenses and alteration of phase I activities as mechanisms of chemoprotective effects of coffee in the liver.

    PubMed

    Cavin, C; Marin-Kuan, M; Langouët, S; Bezençon, C; Guignard, G; Verguet, C; Piguet, D; Holzhäuser, D; Cornaz, R; Schilter, B

    2008-04-01

    Coffee consumption has been associated with a significant decrease in the risk of developing chronic diseases such as Parkinson disease, diabetes type-2 and several types of cancers (e.g. colon, liver). In the present study, a coffee-dependent induction of enzymes involved in xenobiotic detoxification processes was observed in rat liver and primary hepatocytes. In addition, coffee was found to induce the mRNA and protein expression of enzymes involved in cellular antioxidant defenses. These inductions were correlated with the activation of the Nrf2 transcription factor as shown using an ARE-reporter luciferase assay. The induction of detoxifying enzymes GSTs and AKR is compatible with a protection against both genotoxicity and cytotoxicity of aflatoxin B1 (AFB1). This hypothesis was confirmed in in vitro and ex vivo test systems, where coffee reduced both AFB1-DNA and protein adducts. Interestingly, coffee was also found to inhibit cytochrome CYP1A1/2, indicating that other mechanisms different from a stimulation of detoxification may also play a significant role in the chemoprotective effects of coffee. Further investigations in either human liver cell line and primary hepatocytes indicated that the chemoprotective effects of coffee against AFB1 genotoxicity are likely to be of relevance for humans. These data strongly suggest that coffee may protect against the adverse effects of AFB1. In addition, the coffee-mediated stimulation of the Nrf2-ARE pathway resulting in increased endogenous defense mechanisms against electrophilic but also oxidative insults further support that coffee may be associated with a protection against various types of chemical stresses.

  11. Induction of Nrf2-mediated cellular defenses and alteration of phase I activities as mechanisms of chemoprotective effects of coffee in the liver.

    PubMed

    Cavin, C; Marin-Kuan, M; Langouët, S; Bezençon, C; Guignard, G; Verguet, C; Piguet, D; Holzhäuser, D; Cornaz, R; Schilter, B

    2008-04-01

    Coffee consumption has been associated with a significant decrease in the risk of developing chronic diseases such as Parkinson disease, diabetes type-2 and several types of cancers (e.g. colon, liver). In the present study, a coffee-dependent induction of enzymes involved in xenobiotic detoxification processes was observed in rat liver and primary hepatocytes. In addition, coffee was found to induce the mRNA and protein expression of enzymes involved in cellular antioxidant defenses. These inductions were correlated with the activation of the Nrf2 transcription factor as shown using an ARE-reporter luciferase assay. The induction of detoxifying enzymes GSTs and AKR is compatible with a protection against both genotoxicity and cytotoxicity of aflatoxin B1 (AFB1). This hypothesis was confirmed in in vitro and ex vivo test systems, where coffee reduced both AFB1-DNA and protein adducts. Interestingly, coffee was also found to inhibit cytochrome CYP1A1/2, indicating that other mechanisms different from a stimulation of detoxification may also play a significant role in the chemoprotective effects of coffee. Further investigations in either human liver cell line and primary hepatocytes indicated that the chemoprotective effects of coffee against AFB1 genotoxicity are likely to be of relevance for humans. These data strongly suggest that coffee may protect against the adverse effects of AFB1. In addition, the coffee-mediated stimulation of the Nrf2-ARE pathway resulting in increased endogenous defense mechanisms against electrophilic but also oxidative insults further support that coffee may be associated with a protection against various types of chemical stresses. PMID:17976884

  12. Stress, sex and neural adaptation to a changing environment: mechanisms of neuronal remodeling

    PubMed Central

    McEwen, Bruce S.

    2010-01-01

    The adult brain is much more resilient and adaptable than previously believed, and adaptive structural plasticity involves growth and shrinkage of dendritic trees, turnover of synapses and limited amounts of neurogenesis in the forebrain, especially the dentate gyrus of the hippocampal formation. Stress and sex hormones help to mediate adaptive structural plasticity, which has been extensively investigated in hippocampus and to a lesser extent in prefrontal cortex and amygdala, all brain regions that are involved in cognitive and emotional functions. Stress and sex hormones exert their effects on brain structural remodeling through both classical genomic as well as non-genomic mechanisms, and they do so in collaboration with neurotransmitters and other intra- and extracellular mediators. This review will illustrate the actions of estrogen on synapse formation in the hippocampus and the process of stress-induced remodelling of dendrites and synapses in the hippocampus, amygdala and prefrontal cortex. The influence of early developmental epigenetic events, such as early life stress and brain sexual differentiation, is noted along with the interactions between sex hormones and the effects of stress on the brain. Because hormones influence brain structure and function and because hormone secretion is governed by the brain, applied molecular neuroscience techniques can begin to reveal the role of hormones in brain-related disorders and the treatment of these diseases. A better understanding of hormone-brain interactions should promote more flexible approaches to the treatment of psychiatric disorders, as well as their prevention through both behavioral and pharmaceutical interventions. PMID:20840167

  13. Integrated approach for studying adaptation mechanisms in the human somatosensory cortical network.

    PubMed

    Venkatesan, Lalit; Barlow, Steven M; Popescu, Mihai; Popescu, Anda

    2014-11-01

    Magnetoencephalography and independent component analysis (ICA) was utilized to study and characterize neural adaptation in the somatosensory cortical network. Repetitive punctate tactile stimuli were applied unilaterally to the dominant hand and face using a custom-built pneumatic stimulator called the TAC-Cell. ICA-based source estimation from the evoked neuromagnetic responses indicated cortical activity in the contralateral primary somatosensory cortex (SI) for face stimulation, while hand stimulation resulted in robust contralateral SI and posterior parietal cortex (PPC) activation. Activity was also observed in the secondary somatosensory cortical area (SII) with reduced amplitude and higher variability across subjects. There was a significant difference in adaptation rate between SI and higher-order somatosensory cortices for hand stimulation. Adaptation was significantly dependent on stimulus frequency and pulse index within the stimulus train for both hand and face stimulation. The peak latency of the activity was significantly dependent on stimulation site (hand vs. face) and cortical area (SI vs. PPC). The difference in the peak latency of activity in SI and PPC is presumed to reflect a hierarchical serial-processing mechanism in the somatosensory cortex.

  14. Adaptive Transgenerational Plasticity in Plants: Case Studies, Mechanisms, and Implications for Natural Populations

    PubMed Central

    Herman, Jacob J.; Sultan, Sonia E.

    2011-01-01

    Plants respond to environmental conditions not only by plastic changes to their own development and physiology, but also by altering the phenotypes expressed by their offspring. This transgenerational plasticity was initially considered to entail only negative effects of stressful parental environments, such as production of smaller seeds by resource- or temperature-stressed parent plants, and was therefore viewed as environmental noise. Recent evolutionary ecology studies have shown that in some cases, these inherited environmental effects can include specific growth adjustments that are functionally adaptive to the parental conditions that induced them, which can range from contrasting states of controlled laboratory environments to the complex habitat variation encountered by natural plant populations. Preliminary findings suggest that adaptive transgenerational effects can be transmitted by means of diverse mechanisms including changes to seed provisioning and biochemistry, and epigenetic modifications such as DNA methylation that can persist across multiple generations. These non-genetically inherited adaptations can influence the ecological breadth and evolutionary dynamics of plant taxa and promote the spread of invasive plants. Interdisciplinary studies that join mechanistic and evolutionary ecology approaches will be an important source of future insights. PMID:22639624

  15. Adaptive immunity to fungi.

    PubMed

    Verma, Akash; Wüthrich, Marcel; Deepe, George; Klein, Bruce

    2014-11-06

    Life-threatening fungal infections have risen sharply in recent years, owing to the advances and intensity of medical care that may blunt immunity in patients. This emerging crisis has created the growing need to clarify immune defense mechanisms against fungi with the ultimate goal of therapeutic intervention. We describe recent insights in understanding the mammalian immune defenses that are deployed against pathogenic fungi. We focus on adaptive immunity to the major medically important fungi and emphasize three elements that coordinate the response: (1) dendritic cells and subsets that are mobilized against fungi in various anatomical compartments; (2) fungal molecular patterns and their corresponding receptors that signal responses and shape the differentiation of T-cell subsets and B cells; and, ultimately (3) the effector and regulatory mechanisms that eliminate these invaders while constraining collateral damage to vital tissue. These insights create a foundation for the development of new, immune-based strategies for prevention or enhanced clearance of systemic fungal diseases.

  16. Adaptive immunity to fungi.

    PubMed

    Wüthrich, Marcel; Deepe, George S; Klein, Bruce

    2012-01-01

    Only a handful of the more than 100,000 fungal species on our planet cause disease in humans, yet the number of life-threatening fungal infections in patients has recently skyrocketed as a result of advances in medical care that often suppress immunity intensely. This emerging crisis has created pressing needs to clarify immune defense mechanisms against fungi, with the ultimate goal of therapeutic applications. Herein, we describe recent insights in understanding the mammalian immune defenses deployed against pathogenic fungi. The review focuses on adaptive immune responses to the major medically important fungi and emphasizes how dendritic cells and subsets in various anatomic compartments respond to fungi, recognize their molecular patterns, and signal responses that nurture and shape the differentiation of T cell subsets and B cells. Also emphasized is how the latter deploy effector and regulatory mechanisms that eliminate these nasty invaders while also constraining collateral damage to vital tissue.

  17. Evidence for a common motion mechanism of luminance-modulated and contrast-modulated patterns: selective adaptation.

    PubMed

    Turano, K

    1991-01-01

    Selective adaptation effects were measured with contrast-modulated patterns and sine-wave gratings in order to determine the extent to which the two patterns are processed by common mechanisms. Direction-specific adaptation effects were measured for a contrast-modulated adapting pattern and a test pattern. The contrast-modulated adapting pattern was composed of a sine-wave grating of 8 cycles deg-1 whose contrast was spatially modulated by a sinusoid of 1 cycle deg-1 at one of four levels: 100%, 60%, 30%, or 0%. The results showed that contrast-modulation thresholds for contrast-modulated gratings were raised by 0.3 to 0.5 log units following adaptation to a contrast-modulated grating moving in the same direction as the test pattern, relative to thresholds obtained following adaptation to a contrast-modulated grafting moving in the opposite direction. Cross-adaptation effects were also measured with a sine-wave adapting pattern and a contrast-modulated test pattern. The sine-wave adapting pattern was a sine-wave grating of 1 cycle deg-1 whose contrast was set to one of three levels: 16.4%, 1.25%, or 0%. The contrast-modulated test pattern was a sine-wave grating of 8 cycles deg-1 whose contrast was modulated by a sinusoid of 1 cycle deg-1. The results revealed that contrast-modulation thresholds for contrast-modulated gratings were raised by approximately 0.25 log units following adaptation to moving sine-wave gratings, relative to thresholds obtained following adaptation to a uniform field. Cross-adaptation effects were also obtained with a contrast-modulated adapting pattern and a sine-wave test pattern. The results support the view that signals generated from luminance-domain stimuli and from contrast-domain stimuli are processed by a common motion mechanism.

  18. Adaptations for economical bipedal running: the effect of limb structure on three-dimensional joint mechanics.

    PubMed

    Rubenson, Jonas; Lloyd, David G; Heliams, Denham B; Besier, Thor F; Fournier, Paul A

    2011-05-01

    The purpose of this study was to examine the mechanical adaptations linked to economical locomotion in cursorial bipeds. We addressed this question by comparing mass-matched humans and avian bipeds (ostriches), which exhibit marked differences in limb structure and running economy. We hypothesized that the nearly 50 per cent lower energy cost of running in ostriches is a result of: (i) lower limb-swing mechanical power, (ii) greater stance-phase storage and release of elastic energy, and (iii) lower total muscle power output. To test these hypotheses, we used three-dimensional joint mechanical measurements and a simple model to estimate the elastic and muscle contributions to joint work and power. Contradictory to our first hypothesis, we found that ostriches and humans generate the same amounts of mechanical power to swing the limbs at a similar self-selected running speed, indicating that limb swing probably does not contribute to the difference in energy cost of running between these species. In contrast, we estimated that ostriches generate 120 per cent more stance-phase mechanical joint power via release of elastic energy compared with humans. This elastic mechanical power occurs nearly exclusively at the tarsometatarso-phalangeal joint, demonstrating a shift of mechanical power generation to distal joints compared with humans. We also estimated that positive muscle fibre power is 35 per cent lower in ostriches compared with humans, and is accounted for primarily by higher capacity for storage and release of elastic energy. Furthermore, our analysis revealed much larger frontal and internal/external rotation joint loads during ostrich running than in humans. Together, these findings support the hypothesis that a primary limb structure specialization linked to economical running in cursorial species is an elevated storage and release of elastic energy in tendon. In the ostrich, energy-saving specializations may also include passive frontal and internal

  19. Visual motion aftereffects arise from a cascade of two isomorphic adaptation mechanisms

    PubMed Central

    Stocker, Alan A.; Simoncelli, Eero P.

    2013-01-01

    Prolonged exposure to a moving stimulus can substantially alter the perceived velocity (both speed and direction) of subsequently presented stimuli. Here, we show that these changes can be parsimoniously explained with a model that combines the effects of two isomorphic adaptation mechanisms, one nondirectional and one directional. Each produces a pattern of velocity biases that serves as an observable “signature” of the corresponding mechanism. The net effect on perceived velocity is a superposition of these two signatures. By examining human velocity judgments in the context of different adaptor velocities, we are able to separate these two signatures. The model fits the data well, successfully predicts subjects’ behavior in an additional experiment using a nondirectional adaptor, and is in agreement with a variety of previous experimental results. As such, the model provides a unifying explanation for the diversity of motion aftereffects. PMID:19761342

  20. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    PubMed Central

    Giannattasio, Sergio; Guaragnella, Nicoletta; Ždralević, Maša; Marra, Ersilia

    2013-01-01

    Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications. PMID:23430312

  1. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid.

    PubMed

    Giannattasio, Sergio; Guaragnella, Nicoletta; Zdralević, Maša; Marra, Ersilia

    2013-01-01

    Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications. PMID:23430312

  2. Poly(ethylene glycol) Hydrogels with Adaptable Mechanical and Degradation Properties for Use in Biomedical Applicationsa

    PubMed Central

    Parlato, Matthew; Reichert, Sarah; Barney, Neal

    2014-01-01

    Requirements of hydrogels for drug delivery, wound dressings, and surgical implantation can be extensive, including suitable mechanical properties and tailorable degradation time frames. Herein, an adaptable PEG-based hydrogel, whose mechanical properties and degradation rate can be systematically adjusted to meet these criteria by altering simple variables such as the PEG molecular weight, is described. The performance of these hydrogels in three physical manipulations (pushing, pulling, and folding), representative of manipulations that they may undergo during typical biomedical use, is also assessed. While not all of these formulations can withstand these manipulations, a subset did, and it is intended to further optimize these formulations for specific clinical applications. Additionally, the outcomes of the physical manipulation tests indicate that simply having a high modulus does not correlate with biomedical applicability. PMID:24949497

  3. Adaptation of Gabor filters for simulation of human preattentive mechanism for a mobile robot

    NASA Astrophysics Data System (ADS)

    Kulkarni, Naren; Naghdy, Golshah A.

    1993-08-01

    Vision guided mobile robot navigation is complex and requires analysis of tremendous amounts of information in real time. In order to simplify the task and reduce the amount of information, human preattentive mechanism can be adapted [Nag90]. During the preattentive search the scene is analyzed rapidly but in sufficient detail for the attention to be focused on the `area of interest.' The `area of interest' can further be scrutinized in more detail for recognition purposes. This `area of interest' can be a text message to facilitate navigation. Gabor filters and an automated turning mechanism are used to isolate the `area of interest.' These regions are subsequently processed with optimal spatial resolution for perception tasks. This method has clear advantages over the global operators in that, after an initial search, it scans each region of interest with optimum resolution. This reduces the volume of information for recognition stages and ensures that no region is over or under estimated.

  4. Influence of background size, luminance and eccentricity on different adaptation mechanisms.

    PubMed

    Gloriani, Alejandro H; Matesanz, Beatriz M; Barrionuevo, Pablo A; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A

    2016-08-01

    Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06-110cd/m(2)) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5cd/m(2). In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range.

  5. Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

    PubMed Central

    CASSELLI, Denise Sá Maia; FARIA-E-SILVA, André Luis; CASSELLI, Henrique; MARTINS, Luis Roberto Marcondes

    2013-01-01

    Objective: This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations. Material and Methods: Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5ºC±2ºC followed by 55ºC±2ºC - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (a=0.05). Results: The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition. Conclusions: The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations. PMID:23559115

  6. A Dopamine- and Protein Kinase A-Dependent Mechanism for Network Adaptation in Retinal Ganglion Cells

    PubMed Central

    Vaquero, C. F.; Pignatelli, A.; Partida, G. J.; Ishida, A. T.

    2011-01-01

    Vertebrates can detect light intensity changes in vastly different photic environments, in part, because post-receptoral neurons undergo “network adaptation”. Previous data implicated dopaminergic, cAMP-dependent inhibition of retinal ganglion cells in this process, yet left unclear how this occurs, and whether this occurs in darkness versus light. To test for light- and dopamine-dependent changes in ganglion cell cAMP levels in situ, we immunostained dark- and light-adapted retinas with anti-cAMP antisera, in the presence and absence of various dopamine receptor ligands. To test for direct effects of dopamine receptor ligands and membrane-permeable protein kinase ligands on ganglion cell excitability, we recorded spikes from isolated ganglion cells in perforated-patch whole-cell mode, before and during application of these agents by microperfusion. Our immunostainings show that light, endogenous dopamine, and exogenous dopamine elevate ganglion cell cAMP levels in situ by activating D1-type dopamine receptors. Our spike recordings show that D1-type agonists and 8-bromo cAMP reduce spike frequency and curtail sustained spike firing, and that these effects entail protein kinase A activation. These effects resemble those of background light on ganglion cell responses to light flashes. Network adaptation could thus be produced, to some extent, by dopaminergic modulation of ganglion cell spike generation, a mechanism distinct from modulation of transmitter release onto ganglion cells or of transmitter-gated currents in ganglion cells. Combining these observations, with results obtained in studies of photoreceptor, bipolar, and horizontal cells, indicates that all three layers of neurons in the retina are equipped with mechanisms for adaptation to ambient light. PMID:11606650

  7. [PROTEOMIC ANALYSIS OF ADAPTIVE MECHANISMS TO SALINITY STRESS IN MARINE GASTROPODS LITTORINA SAXATILIS].

    PubMed

    Muraeva, O A; Maltseva, A L; Mikhailova, N A; Granovitch, A I

    2015-01-01

    Salinity is one of the most important abiotic environmental factors affecting marine animals. If salinity deviate from optimum, adaptive mechanisms switch on to maintain organism's physiological activity. In this study, the reaction of the snails Littorina saxatilis from natural habitats and in response to experimental salinity decreasing was analyzed on proteomic level. The isolation of all snails inside their shells and gradually declining mortality was observed under acute experimental salinity decrease (down to 10 per hundred). Proteomic changes were evaluated in the surviving experimental mollusks compared to control individual using differential 2D gel-electrophoresis (DIGE) and subsequent LC-MS/MS-identification of proteins. Approximately 10% of analyzed proteins underwent up- or down regulation during the experiment. Proteins of folding, antioxidant response, intercellular matrix, cell adhesion, cell signaling and metabolic enzymes were identified among them. Proteome changes observed in experimental hypoosmotic stress partially reproduced in the proteomes of mollusks that live in conditions of natural freshening (estuaries). Possible mechanisms involved in the adaptation process of L. saxatilis individuals to hypo-osmotic stress are discussed. PMID:26995971

  8. Mechanically adaptive intracortical implants improve the proximity of neuronal cell bodies

    NASA Astrophysics Data System (ADS)

    Harris, J. P.; Capadona, J. R.; Miller, R. H.; Healy, B. C.; Shanmuganathan, K.; Rowan, S. J.; Weder, C.; Tyler, D. J.

    2011-10-01

    The hypothesis is that the mechanical mismatch between brain tissue and microelectrodes influences the inflammatory response. Our unique, mechanically adaptive polymer nanocomposite enabled this study within the cerebral cortex of rats. The initial tensile storage modulus of 5 GPa decreases to 12 MPa within 15 min under physiological conditions. The response to the nanocomposite was compared to surface-matched, stiffer implants of traditional wires (411 GPa) coated with the identical polymer substrate and implanted on the contralateral side. Both implants were tethered. Fluorescent immunohistochemistry labeling examined neurons, intermediate filaments, macrophages, microglia and proteoglycans. We demonstrate, for the first time, a system that decouples the mechanical and surface chemistry components of the neural response. The neuronal nuclei density within 100 µm of the device at four weeks post-implantation was greater for the compliant nanocomposite compared to the stiff wire. At eight weeks post-implantation, the neuronal nuclei density around the nanocomposite was maintained, but the density around the wire recovered to match that of the nanocomposite. The glial scar response to the compliant nanocomposite was less vigorous than it was to the stiffer wire. The results suggest that mechanically associated factors such as proteoglycans and intermediate filaments are important modulators of the response of the compliant nanocomposite.

  9. Mechanically adaptive intracortical implants improve the proximity of neuronal cell bodies.

    PubMed

    Harris, J P; Capadona, J R; Miller, R H; Healy, B C; Shanmuganathan, K; Rowan, S J; Weder, C; Tyler, D J

    2011-12-01

    The hypothesis is that the mechanical mismatch between brain tissue and microelectrodes influences the inflammatory response. Our unique, mechanically adaptive polymer nanocomposite enabled this study within the cerebral cortex of rats. The initial tensile storage modulus of 5 GPa decreases to 12 MPa within 15 min under physiological conditions. The response to the nanocomposite was compared to surface-matched, stiffer implants of traditional wires (411 GPa) coated with the identical polymer substrate and implanted on the contralateral side. Both implants were tethered. Fluorescent immunohistochemistry labeling examined neurons, intermediate filaments, macrophages, microglia and proteoglycans. We demonstrate, for the first time, a system that decouples the mechanical and surface chemistry components of the neural response. The neuronal nuclei density within 100 µm of the device at four weeks post-implantation was greater for the compliant nanocomposite compared to the stiff wire. At eight weeks post-implantation, the neuronal nuclei density around the nanocomposite was maintained, but the density around the wire recovered to match that of the nanocomposite. The glial scar response to the compliant nanocomposite was less vigorous than it was to the stiffer wire. The results suggest that mechanically associated factors such as proteoglycans and intermediate filaments are important modulators of the response of the compliant nanocomposite. PMID:22049097

  10. Response and Defense Mechanisms of Taxus chinensis Leaves Under UV-A Radiation are Revealed Using Comparative Proteomics and Metabolomics Analyses.

    PubMed

    Zheng, Wen; Komatsu, Setsuko; Zhu, Wei; Zhang, Lin; Li, Ximin; Cui, Lei; Tian, Jingkui

    2016-09-01

    Taxus chinensis var. mairei is a species endemic to south-eastern China and one of the natural sources for the anticancer medicine paclitaxel. To investigate the molecular response and defense mechanisms of T. chinensis leaves to enhanced ultraviolet-A (UV-A) radiation, gel-free/label-free and gel-based proteomics and gas chromatography-mass spectrometry (GC-MS) analyses were performed. The transmission electron microscopy results indicated damage to the chloroplast under UV-A radiation. Proteomics analyses in leaves and chloroplasts showed that photosynthesis-, glycolysis-, secondary metabolism-, stress-, and protein synthesis-, degradation- and activation-related systems were mainly changed under UV-A radiation. Forty-seven PSII proteins and six PSI proteins were identified as being changed in leaves and chloroplasts under UV-A treatment. This indicated that PSII was more sensitive to UV-A than PSI as the target of UV-A light. Enhanced glycolysis, with four glycolysis-related key enzymes increased, provided precursors for secondary metabolism. The 1-deoxy-d-xylulose-5-phosphate reductoisomerase and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase were identified as being significantly increased during UV-A radiation, which resulted in paclitaxel enhancement. Additionally, mRNA expression levels of genes involved in the paclitaxel biosynthetic pathway indicated a down-regulation under UV-A irradiation and up-regulation in dark incubation. These results reveal that a short-term high dose of UV-A radiation could stimulate the plant stress defense system and paclitaxel production. PMID:27318281

  11. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process.

    PubMed

    Subramanian, Veedamali S; Ghosal, Abhisek; Kapadia, Rubina; Nabokina, Svetlana M; Said, Hamid M

    2015-01-01

    The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level.

  12. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process

    PubMed Central

    Subramanian, Veedamali S.; Ghosal, Abhisek; Kapadia, Rubina; Nabokina, Svetlana M.; Said, Hamid M.

    2015-01-01

    The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level. PMID:26121134

  13. Influence of resveratrol release on the tissue response to mechanically adaptive cortical implants.

    PubMed

    Nguyen, Jessica K; Jorfi, Mehdi; Buchanan, Kelly L; Park, Daniel J; Foster, E Johan; Tyler, Dustin J; Rowan, Stuart J; Weder, Christoph; Capadona, Jeffrey R

    2016-01-01

    The stability and longevity of recordings obtained from intracortical microelectrodes continues to remain an area of concern for neural interfacing applications. The limited longevity of microelectrode performance has been associated with the integrity of the blood brain barrier (BBB) and the neuroinflammatory response to the microelectrode. Here, we report the investigation of an additive approach that targets both mechanical and chemical factors believed to contribute to chronic BBB instability and the neuroinflammatory response associated with implanted intracortical microelectrodes. The implants investigated were based on a mechanically adaptive, compliant nanocomposite (NC), which reduces the tissue response and tissue strain. This material was doped with various concentrations of the antioxidant resveratrol with the objective of local and rapid delivery. In vitro analysis of resveratrol release, antioxidant activity, and cytotoxicity suggested that a resveratrol content of 0.01% was optimal for in vivo assessment. Thus, probes made from the neat NC reference and probes containing resveratrol (NC Res) were implanted into the cortical tissue of rats for up to sixteen weeks. Histochemical analysis suggested that at three days post-implantation, neither materials nor therapeutic approaches (independently or in combination) could alter the initial wound healing response. However, at two weeks post-implantation, the NC Res implant showed a reduction in activated microglia/macrophages and improvement in neuron density at the tissue-implant interface when compared to the neat NC reference. However, sixteen weeks post-implantation, when the antioxidant was exhausted, NC Res and the neat NC reference exhibited similar tissue responses. The data show that NC Res provides short-term, short-lived benefits due to the antioxidant release, and a long-term reduction in neuroinflammation on account of is mechanical adaptive, compliant nature. Together, these results

  14. Influence of resveratrol release on the tissue response to mechanically adaptive cortical implants.

    PubMed

    Nguyen, Jessica K; Jorfi, Mehdi; Buchanan, Kelly L; Park, Daniel J; Foster, E Johan; Tyler, Dustin J; Rowan, Stuart J; Weder, Christoph; Capadona, Jeffrey R

    2016-01-01

    The stability and longevity of recordings obtained from intracortical microelectrodes continues to remain an area of concern for neural interfacing applications. The limited longevity of microelectrode performance has been associated with the integrity of the blood brain barrier (BBB) and the neuroinflammatory response to the microelectrode. Here, we report the investigation of an additive approach that targets both mechanical and chemical factors believed to contribute to chronic BBB instability and the neuroinflammatory response associated with implanted intracortical microelectrodes. The implants investigated were based on a mechanically adaptive, compliant nanocomposite (NC), which reduces the tissue response and tissue strain. This material was doped with various concentrations of the antioxidant resveratrol with the objective of local and rapid delivery. In vitro analysis of resveratrol release, antioxidant activity, and cytotoxicity suggested that a resveratrol content of 0.01% was optimal for in vivo assessment. Thus, probes made from the neat NC reference and probes containing resveratrol (NC Res) were implanted into the cortical tissue of rats for up to sixteen weeks. Histochemical analysis suggested that at three days post-implantation, neither materials nor therapeutic approaches (independently or in combination) could alter the initial wound healing response. However, at two weeks post-implantation, the NC Res implant showed a reduction in activated microglia/macrophages and improvement in neuron density at the tissue-implant interface when compared to the neat NC reference. However, sixteen weeks post-implantation, when the antioxidant was exhausted, NC Res and the neat NC reference exhibited similar tissue responses. The data show that NC Res provides short-term, short-lived benefits due to the antioxidant release, and a long-term reduction in neuroinflammation on account of is mechanical adaptive, compliant nature. Together, these results

  15. (1)H NMR and GC-MS Based Metabolomics Reveal Defense and Detoxification Mechanism of Cucumber Plant under Nano-Cu Stress.

    PubMed

    Zhao, Lijuan; Huang, Yuxiong; Hu, Jerry; Zhou, Hongjun; Adeleye, Adeyemi S; Keller, Arturo A

    2016-02-16

    Because copper nanoparticles are being increasingly used in agriculture as pesticides, it is important to assess their potential implications for agriculture. Concerns have been raised about the bioaccumulation of nano-Cu and their toxicity to crop plants. Here, the response of cucumber plants in hydroponic culture at early development stages to two concentrations of nano-Cu (10 and 20 mg/L) was evaluated by proton nuclear magnetic resonance spectroscopy ((1)H NMR) and gas chromatography-mass spectrometry (GC-MS) based metabolomics. Changes in mineral nutrient metabolism induced by nano-Cu were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that nano-Cu at both concentrations interferes with the uptake of a number of micro- and macro-nutrients, such as Na, P, S, Mo, Zn, and Fe. Metabolomics data revealed that nano-Cu at both levels triggered significant metabolic changes in cucumber leaves and root exudates. The root exudate metabolic changes revealed an active defense mechanism against nano-Cu stress: up-regulation of amino acids to sequester/exclude Cu/nano-Cu; down-regulation of citric acid to reduce the mobilization of Cu ions; ascorbic acid up-regulation to combat reactive oxygen species; and up-regulation of phenolic compounds to improve antioxidant system. Thus, we demonstrate that nontargeted (1)H NMR and GC-MS based metabolomics can successfully identify physiological responses induced by nanoparticles. Root exudates metabolomics revealed important detoxification mechanisms.

  16. (1)H NMR and GC-MS Based Metabolomics Reveal Defense and Detoxification Mechanism of Cucumber Plant under Nano-Cu Stress.

    PubMed

    Zhao, Lijuan; Huang, Yuxiong; Hu, Jerry; Zhou, Hongjun; Adeleye, Adeyemi S; Keller, Arturo A

    2016-02-16

    Because copper nanoparticles are being increasingly used in agriculture as pesticides, it is important to assess their potential implications for agriculture. Concerns have been raised about the bioaccumulation of nano-Cu and their toxicity to crop plants. Here, the response of cucumber plants in hydroponic culture at early development stages to two concentrations of nano-Cu (10 and 20 mg/L) was evaluated by proton nuclear magnetic resonance spectroscopy ((1)H NMR) and gas chromatography-mass spectrometry (GC-MS) based metabolomics. Changes in mineral nutrient metabolism induced by nano-Cu were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that nano-Cu at both concentrations interferes with the uptake of a number of micro- and macro-nutrients, such as Na, P, S, Mo, Zn, and Fe. Metabolomics data revealed that nano-Cu at both levels triggered significant metabolic changes in cucumber leaves and root exudates. The root exudate metabolic changes revealed an active defense mechanism against nano-Cu stress: up-regulation of amino acids to sequester/exclude Cu/nano-Cu; down-regulation of citric acid to reduce the mobilization of Cu ions; ascorbic acid up-regulation to combat reactive oxygen species; and up-regulation of phenolic compounds to improve antioxidant system. Thus, we demonstrate that nontargeted (1)H NMR and GC-MS based metabolomics can successfully identify physiological responses induced by nanoparticles. Root exudates metabolomics revealed important detoxification mechanisms. PMID:26751164

  17. DIGESTIVE PHYSIOLOGY OF THE PIG SYMPOSIUM: Involvement of gut chemosensing in the regulation of mucosal barrier function and defense mechanisms1,2

    PubMed Central

    Kaji, I.; Akiba, Y.; Kaunitz, J. D.

    2016-01-01

    Meal ingestion is followed by release of numerous hormones from enteroendocrine cells interspersed among the epithelial cells lining the intestine. Recently, the de-orphanization of G protein-coupled receptor (GPCR)-type nutrient receptors, expressed on the apical membranes of enteroendocrine cells, has suggested a plausible mechanism whereby luminal nutrients trigger the release of gut hormones. Activation of nutrient receptors triggers intracellular signaling mechanisms that promote exocytosis of hormone-containing granules into the submucosal space. Hormones released by foregut enteroendocrine cells include the glucagon-like peptides (GLP) affecting glycemic control (GLP-1) and releasing pro-proliferative, hypertrophy-inducing growth factors (GLP-2). The foregut mucosa, being exposed to pulses of concentrated HCl, is protected by a system of defense mechanisms, which includes epithelial bicarbonate and mucus secretion and augmentation of mucosal blood flow. We have reported that luminal co-perfusion of AA with nucleotides in anesthetized rats releases GLP-2 into the portal vein, associated with increased bicarbonate and mucus secretion and mucosal blood flow. The GLP-2 increases bicarbonate secretion via release of vasoactive intestinal peptide (VIP) from myenteric nerves. Luminal bile acids also release gut hormones due to activation of the bile-acid receptor known as G Protein-Coupled Receptor (GPR) 131, G Protein Bile Acid Receptor (GPBAR) 1, or Takeda G Protein-Coupled Receptor (TGR) 5, also expressed on enteroendocrine cells. The GLP are metabolized by dipeptidyl peptidase IV (DPPIV), an enzyme of particular interest to pharmaceutical, because its inhibition increases plasma concentrations of GLP-1 to treat diabetes. We have also reported that DPPIV inhibition enhances the secretory effects of nutrient-evoked GLP-2. Understanding the release mechanism and the metabolic pathways of gut hormones is of potential utility to the formulation of feedstuff

  18. Mechanisms Underlying Adaptation to Life in Hydrogen Sulfide–Rich Environments

    PubMed Central

    Kelley, Joanna L.; Arias-Rodriguez, Lenin; Patacsil Martin, Dorrelyn; Yee, Muh-Ching; Bustamante, Carlos D.; Tobler, Michael

    2016-01-01

    Hydrogen sulfide (H2S) is a potent toxicant interfering with oxidative phosphorylation in mitochondria and creating extreme environmental conditions in aquatic ecosystems. The mechanistic basis of adaptation to perpetual exposure to H2S remains poorly understood. We investigated evolutionarily independent lineages of livebearing fishes that have colonized and adapted to springs rich in H2S and compared their genome-wide gene expression patterns with closely related lineages from adjacent, nonsulfidic streams. Significant differences in gene expression were uncovered between all sulfidic and nonsulfidic population pairs. Variation in the number of differentially expressed genes among population pairs corresponded to differences in divergence times and rates of gene flow, which is consistent with neutral drift driving a substantial portion of gene expression variation among populations. Accordingly, there was little evidence for convergent evolution shaping large-scale gene expression patterns among independent sulfide spring populations. Nonetheless, we identified a small number of genes that was consistently differentially expressed in the same direction in all sulfidic and nonsulfidic population pairs. Functional annotation of shared differentially expressed genes indicated upregulation of genes associated with enzymatic H2S detoxification and transport of oxidized sulfur species, oxidative phosphorylation, energy metabolism, and pathways involved in responses to oxidative stress. Overall, our results suggest that modification of processes associated with H2S detoxification and toxicity likely complement each other to mediate elevated H2S tolerance in sulfide spring fishes. Our analyses allow for the development of novel hypotheses about biochemical and physiological mechanisms of adaptation to extreme environments. PMID:26861137

  19. Mechanisms Underlying Adaptation to Life in Hydrogen Sulfide-Rich Environments.

    PubMed

    Kelley, Joanna L; Arias-Rodriguez, Lenin; Patacsil Martin, Dorrelyn; Yee, Muh-Ching; Bustamante, Carlos D; Tobler, Michael

    2016-06-01

    Hydrogen sulfide (H2S) is a potent toxicant interfering with oxidative phosphorylation in mitochondria and creating extreme environmental conditions in aquatic ecosystems. The mechanistic basis of adaptation to perpetual exposure to H2S remains poorly understood. We investigated evolutionarily independent lineages of livebearing fishes that have colonized and adapted to springs rich in H2S and compared their genome-wide gene expression patterns with closely related lineages from adjacent, nonsulfidic streams. Significant differences in gene expression were uncovered between all sulfidic and nonsulfidic population pairs. Variation in the number of differentially expressed genes among population pairs corresponded to differences in divergence times and rates of gene flow, which is consistent with neutral drift driving a substantial portion of gene expression variation among populations. Accordingly, there was little evidence for convergent evolution shaping large-scale gene expression patterns among independent sulfide spring populations. Nonetheless, we identified a small number of genes that was consistently differentially expressed in the same direction in all sulfidic and nonsulfidic population pairs. Functional annotation of shared differentially expressed genes indicated upregulation of genes associated with enzymatic H2S detoxification and transport of oxidized sulfur species, oxidative phosphorylation, energy metabolism, and pathways involved in responses to oxidative stress. Overall, our results suggest that modification of processes associated with H2S detoxification and toxicity likely complement each other to mediate elevated H2S tolerance in sulfide spring fishes. Our analyses allow for the development of novel hypotheses about biochemical and physiological mechanisms of adaptation to extreme environments.

  20. Bulgy tadpoles: inducible defense morph.

    PubMed

    Kishida, Osamu; Nishimura, Kinya

    2004-08-01

    Predator induced morphological defenses are marked morphological shifts induced directly by cues associated with a predator. Generally, remote cues, i.e., chemical substances emitted from predators or injured conspecifics, are considered to be ideal signals to induce morphological change in aquatic environments rather than close cues, i.e., close chemical or tactile cues, since chemical substances that can propagate over relatively long distances and persist for a long period may allow organisms to keep safe and to deliberately change their morph. In fact, most organisms adopting an inducible morphological defense utilize remote chemical cues to detect predation risk and to produce morphological defenses. In this paper, we report a unique and functionally well designed inducible morphological defense strategy where the induction process requires close cues from a predator. The tadpoles of Rana pirica exhibited a bulgy bodied morphology when threatened with predation by larval salamanders, Hynobius retardatus, in close proximity. Predation trials and a function experiment showed that the induced bulgy morph is an adaptive defense phenotype against the gape-limited predator larval H. retardatus. Furthermore, R. pirica tadpoles use two adaptive strategies in terms of cost saving, i.e., adjustment of the extent of bulginess according to predation risk and reversibility by actual shrink of bulgy body after removing the predation threat. In general, R. pirica hatch earlier than H. retardatus. In natural ponds, during the early developmental stage R. pirica tadpoles live in close proximity to young H. retardatus larvae. As they grow, the salamanders gradually become serious predators and the predator-prey interaction becomes intimate. After a while, predation, cannibalism and metamorphosis decrease the number of salamanders in the ponds, and the predator-prey interaction weakens. Such a phenology in the predator-prey interaction allows the evolution of a close

  1. Bulgy tadpoles: inducible defense morph.

    PubMed

    Kishida, Osamu; Nishimura, Kinya

    2004-08-01

    Predator induced morphological defenses are marked morphological shifts induced directly by cues associated with a predator. Generally, remote cues, i.e., chemical substances emitted from predators or injured conspecifics, are considered to be ideal signals to induce morphological change in aquatic environments rather than close cues, i.e., close chemical or tactile cues, since chemical substances that can propagate over relatively long distances and persist for a long period may allow organisms to keep safe and to deliberately change their morph. In fact, most organisms adopting an inducible morphological defense utilize remote chemical cues to detect predation risk and to produce morphological defenses. In this paper, we report a unique and functionally well designed inducible morphological defense strategy where the induction process requires close cues from a predator. The tadpoles of Rana pirica exhibited a bulgy bodied morphology when threatened with predation by larval salamanders, Hynobius retardatus, in close proximity. Predation trials and a function experiment showed that the induced bulgy morph is an adaptive defense phenotype against the gape-limited predator larval H. retardatus. Furthermore, R. pirica tadpoles use two adaptive strategies in terms of cost saving, i.e., adjustment of the extent of bulginess according to predation risk and reversibility by actual shrink of bulgy body after removing the predation threat. In general, R. pirica hatch earlier than H. retardatus. In natural ponds, during the early developmental stage R. pirica tadpoles live in close proximity to young H. retardatus larvae. As they grow, the salamanders gradually become serious predators and the predator-prey interaction becomes intimate. After a while, predation, cannibalism and metamorphosis decrease the number of salamanders in the ponds, and the predator-prey interaction weakens. Such a phenology in the predator-prey interaction allows the evolution of a close

  2. A Role for the Anti-Viral Host Defense Mechanism in the Phylogenetic Divergence in Baculovirus Evolution

    PubMed Central

    Nagamine, Toshihiro; Sako, Yasushi

    2016-01-01

    Although phylogenic analysis often suggests co-evolutionary relationships between viruses and host organisms, few examples have been reported at the microevolutionary level. Here, we show a possible example in which a species-specific anti-viral response may drive phylogenic divergence in insect virus evolution. Two baculoviruses, Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Bombyx mori nucleopolyhedrovirus (BmNPV), have a high degree of DNA sequence similarity, but exhibit non-overlapping host specificity. In our study of their host-range determination, we found that BmNPV replication in B. mori cells was prevented by AcMNPV-P143 (AcP143), but not BmNPV-P143 (BmP143) or a hybrid P143 protein from a host-range expanded phenotype. This suggests that AcMNPV resistance in B. mori cells depends on AcP143 recognition and that BmNPV uses BmP143 to escapes this recognition. Based on these data, we propose an insect-baculovirus co-evolution scenario in which an ancestor of silkworms exploited an AcMNPV-resistant mechanism; AcMNPV counteracted this resistance via P143 mutations, resulting in the birth of BmNPV. PMID:27244571

  3. A Role for the Anti-Viral Host Defense Mechanism in the Phylogenetic Divergence in Baculovirus Evolution.

    PubMed

    Nagamine, Toshihiro; Sako, Yasushi

    2016-01-01

    Although phylogenic analysis often suggests co-evolutionary relationships between viruses and host organisms, few examples have been reported at the microevolutionary level. Here, we show a possible example in which a species-specific anti-viral response may drive phylogenic divergence in insect virus evolution. Two baculoviruses, Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Bombyx mori nucleopolyhedrovirus (BmNPV), have a high degree of DNA sequence similarity, but exhibit non-overlapping host specificity. In our study of their host-range determination, we found that BmNPV replication in B. mori cells was prevented by AcMNPV-P143 (AcP143), but not BmNPV-P143 (BmP143) or a hybrid P143 protein from a host-range expanded phenotype. This suggests that AcMNPV resistance in B. mori cells depends on AcP143 recognition and that BmNPV uses BmP143 to escapes this recognition. Based on these data, we propose an insect-baculovirus co-evolution scenario in which an ancestor of silkworms exploited an AcMNPV-resistant mechanism; AcMNPV counteracted this resistance via P143 mutations, resulting in the birth of BmNPV. PMID:27244571

  4. Reorganization of extracellular matrix in placentas from women with asymptomatic chagas disease: mechanism of parasite invasion or local placental defense?

    PubMed

    Duaso, Juan; Yanez, Erika; Castillo, Christian; Galanti, Norbel; Cabrera, Gonzalo; Corral, Gabriela; Maya, Juan Diego; Zulantay, Inés; Apt, Werner; Kemmerling, Ulrike

    2012-01-01

    Chagas disease, produced by the protozoan Trypanosoma cruzi (T. cruzi), is one of the most frequent endemic diseases in Latin America. In spite the fact that in the past few years T. cruzi congenital transmission has become of epidemiological importance, studies about this mechanism of infection are scarce. In order to explore some morphological aspects of this infection in the placenta, we analyzed placentas from T. cruzi-infected mothers by immunohistochemical and histochemical methods. Infection in mothers, newborns, and placentas was confirmed by PCR and by immunofluorescence in the placenta. T. cruzi-infected placentas present destruction of the syncytiotrophoblast and villous stroma, selective disorganization of the basal lamina, and disorganization of collagen I in villous stroma. Our results suggest that the parasite induces reorganization of this tissue component and in this way may regulate both inflammatory and immune responses in the host. Changes in the ECM of placental tissues, together with the immunological status of mother and fetus, and parasite load may determine the probability of congenital transmission of T. cruzi.

  5. Reorganization of Extracellular Matrix in Placentas from Women with Asymptomatic Chagas Disease: Mechanism of Parasite Invasion or Local Placental Defense?

    PubMed Central

    Duaso, Juan; Yanez, Erika; Castillo, Christian; Galanti, Norbel; Cabrera, Gonzalo; Corral, Gabriela; Maya, Juan Diego; Zulantay, Inés; Apt, Werner; Kemmerling, Ulrike

    2012-01-01

    Chagas disease, produced by the protozoan Trypanosoma cruzi (T. cruzi), is one of the most frequent endemic diseases in Latin America. In spite the fact that in the past few years T. cruzi congenital transmission has become of epidemiological importance, studies about this mechanism of infection are scarce. In order to explore some morphological aspects of this infection in the placenta, we analyzed placentas from T. cruzi-infected mothers by immunohistochemical and histochemical methods. Infection in mothers, newborns, and placentas was confirmed by PCR and by immunofluorescence in the placenta. T. cruzi-infected placentas present destruction of the syncytiotrophoblast and villous stroma, selective disorganization of the basal lamina, and disorganization of collagen I in villous stroma. Our results suggest that the parasite induces reorganization of this tissue component and in this way may regulate both inflammatory and immune responses in the host. Changes in the ECM of placental tissues, together with the immunological status of mother and fetus, and parasite load may determine the probability of congenital transmission of T. cruzi. PMID:22007243

  6. An Adaptive Jitter Mechanism for Reactive Route Discovery in Sensor Networks

    PubMed Central

    Cordero, Juan Antonio; Yi, Jiazi; Clausen, Thomas

    2014-01-01

    This paper analyses the impact of jitter when applied to route discovery in reactive (on-demand) routing protocols. In multi-hop non-synchronized wireless networks, jitter—a small, random variation in the timing of message emission—is commonly employed, as a means to avoid collisions of simultaneous transmissions by adjacent routers over the same channel. In a reactive routing protocol for sensor and ad hoc networks, jitter is recommended during the route discovery process, specifically, during the network-wide flooding of route request messages, in order to avoid collisions. Commonly, a simple uniform jitter is recommended. Alas, this is not without drawbacks: when applying uniform jitter to the route discovery process, an effect called delay inversion is observed. This paper, first, studies and quantifies this delay inversion effect. Second, this paper proposes an adaptive jitter mechanism, designed to alleviate the delay inversion effect and thereby to reduce the route discovery overhead and (ultimately) allow the routing protocol to find more optimal paths, as compared to uniform jitter. This paper presents both analytical and simulation studies, showing that the proposed adaptive jitter can effectively decrease the cost of route discovery and increase the path quality. PMID:25111238

  7. Integrity of the osteocyte bone cell network in osteoporotic fracture: Implications for mechanical load adaptation

    NASA Astrophysics Data System (ADS)

    Kuliwaba, J. S.; Truong, L.; Codrington, J. D.; Fazzalari, N. L.

    2010-06-01

    The human skeleton has the ability to modify its material composition and structure to accommodate loads through adaptive modelling and remodelling. The osteocyte cell network is now considered to be central to the regulation of skeletal homeostasis; however, very little is known of the integrity of the osteocyte cell network in osteoporotic fragility fracture. This study was designed to characterise osteocyte morphology, the extent of osteocyte cell apoptosis and expression of sclerostin protein (a negative regulator of bone formation) in trabecular bone from the intertrochanteric region of the proximal femur, for postmenopausal women with fragility hip fracture compared to age-matched women who had not sustained fragility fracture. Osteocyte morphology (osteocyte, empty lacunar, and total lacunar densities) and the degree of osteocyte apoptosis (percent caspase-3 positive osteocyte lacunae) were similar between the fracture patients and non-fracture women. The fragility hip fracture patients had a lower proportion of sclerostin-positive osteocyte lacunae in comparison to sclerostin-negative osteocyte lacunae, in contrast to similar percent sclerostin-positive/sclerostin-negative lacunae for non-fracture women. The unexpected finding of decreased sclerostin expression in trabecular bone osteocytes from fracture cases may be indicative of elevated bone turnover and under-mineralisation, characteristic of postmenopausal osteoporosis. Further, altered osteocytic expression of sclerostin may be involved in the mechano-responsiveness of bone. Optimal function of the osteocyte cell network is likely to be a critical determinant of bone strength, acting via mechanical load adaptation, and thus contributing to osteoporotic fracture risk.

  8. Mechanisms of adaptation to chronic respiratory acidosis in the rabbit proximal tubule.

    PubMed Central

    Krapf, R

    1989-01-01

    The hyperbicarbonatemia of chronic respiratory acidosis is maintained by enhanced bicarbonate reabsorption in the proximal tubule. To investigate the cellular mechanisms involved in this adaptation, cell and luminal pH were measured microfluorometrically using (2",7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein in isolated, microperfused S2 proximal convoluted tubules from control and acidotic rabbits. Chronic respiratory acidosis was induced by exposure to 10% CO2 for 52-56 h. Tubules from acidotic rabbits had a significantly lower luminal pH after 1-mm perfused length (7.03 +/- 0.09 vs. 7.26 +/- 0.06 in controls, perfusion rate = 10 nl/min). Chronic respiratory acidosis increased the initial rate of cell acidification (dpHi/dt) in response to luminal sodium removal by 63% and in response to lowering luminal pH (7.4-6.8) by 69%. Chronic respiratory acidosis also increased dpHi/dt in response to peritubular sodium removal by 63% and in response to lowering peritubular pH by 73%. In conclusion, chronic respiratory acidosis induces a parallel increase in the rates of the luminal Na/H antiporter and the basolateral Na/(HCO3)3 cotransporter. Therefore, the enhanced proximal tubule reabsorption of bicarbonate in chronic respiratory acidosis may be, at least in part, mediated by a parallel adaptation of these transporters. PMID:2537851

  9. Differential gene retention as an evolutionary mechanism to generate biodiversity and adaptation in yeasts.

    PubMed

    Morel, Guillaume; Sterck, Lieven; Swennen, Dominique; Marcet-Houben, Marina; Onesime, Djamila; Levasseur, Anthony; Jacques, Noémie; Mallet, Sandrine; Couloux, Arnaux; Labadie, Karine; Amselem, Joëlle; Beckerich, Jean-Marie; Henrissat, Bernard; Van de Peer, Yves; Wincker, Patrick; Souciet, Jean-Luc; Gabaldón, Toni; Tinsley, Colin R; Casaregola, Serge

    2015-06-25

    The evolutionary history of the characters underlying the adaptation of microorganisms to food and biotechnological uses is poorly understood. We undertook comparative genomics to investigate evolutionary relationships of the dairy yeast Geotrichum candidum within Saccharomycotina. Surprisingly, a remarkable proportion of genes showed discordant phylogenies, clustering with the filamentous fungus subphylum (Pezizomycotina), rather than the yeast subphylum (Saccharomycotina), of the Ascomycota. These genes appear not to be the result of Horizontal Gene Transfer (HGT), but to have been specifically retained by G. candidum after the filamentous fungi-yeasts split concomitant with the yeasts' genome contraction. We refer to these genes as SRAGs (Specifically Retained Ancestral Genes), having been lost by all or nearly all other yeasts, and thus contributing to the phenotypic specificity of lineages. SRAG functions include lipases consistent with a role in cheese making and novel endoglucanases associated with degradation of plant material. Similar gene retention was observed in three other distantly related yeasts representative of this ecologically diverse subphylum. The phenomenon thus appears to be widespread in the Saccharomycotina and argues that, alongside neo-functionalization following gene duplication and HGT, specific gene retention must be recognized as an important mechanism for generation of biodiversity and adaptation in yeasts.

  10. Indirect adaptive output feedback control of a biorobotic AUV using pectoral-like mechanical fins.

    PubMed

    Naik, Mugdha S; Singh, Sahjendra N; Mittal, Rajat

    2009-06-01

    This paper treats the question of servoregulation of autonomous underwater vehicles (AUVs) in the yaw plane using pectoral-like mechanical fins. The fins attached to the vehicle have oscillatory swaying and yawing motion. The bias angle of the angular motion of the fin is used for the purpose of control. Of course, the design approach considered here is applicable to AUVs for other choices of oscillation patterns of the fins, which produce periodic forces and moments. It is assumed that the vehicle parameters, hydrodynamic coefficients, as well the fin forces and moments are unknown. For the trajectory control of the yaw angle, a sampled-data indirect adaptive control system using output (yaw angle) feedback is derived. The control system has a modular structure, which includes a parameter identifier and a stabilizer. For the control law derivation, an internal model of the exosignals (reference signal (constant or ramp) and constant disturbance) is included. Unlike the direct adaptive control scheme, the derived control law is applicable to minimum as well as nonminimum phase biorobotic AUVs (BAUVs). This is important, because for most of the fin locations on the vehicle, the model is a nonminimum phase. In the closed-loop system, the yaw angle trajectory tracking error converges to zero and the remaining state variables remain bounded. Simulation results are presented which show that the derived modular control system accomplishes precise set point yaw angle control and turning maneuvers in spite of the uncertainties in the system parameters using only yaw angle feedback.

  11. Integrated physiological mechanisms of exercise performance, adaptation, and maladaptation to heat stress.

    PubMed

    Sawka, Michael N; Leon, Lisa R; Montain, Scott J; Sonna, Larry A

    2011-10-01

    This article emphasizes significant recent advances regarding heat stress and its impact on exercise performance, adaptations, fluid electrolyte imbalances, and pathophysiology. During exercise-heat stress, the physiological burden of supporting high skin blood flow and high sweating rates can impose considerable cardiovascular strain and initiate a cascade of pathophysiological events leading to heat stroke. We examine the association between heat stress, particularly high skin temperature, on diminishing cardiovascular/aerobic reserves as well as increasing relative intensity and perceptual cues that degrade aerobic exercise performance. We discuss novel systemic (heat acclimation) and cellular (acquired thermal tolerance) adaptations that improve performance in hot and temperate environments and protect organs from heat stroke as well as other dissimilar stresses. We delineate how heat stroke evolves from gut underperfusion/ischemia causing endotoxin release or the release of mitochondrial DNA fragments in response to cell necrosis, to mediate a systemic inflammatory syndrome inducing coagulopathies, immune dysfunction, cytokine modulation, and multiorgan damage and failure. We discuss how an inflammatory response that induces simultaneous fever and/or prior exposure to a pathogen (e.g., viral infection) that deactivates molecular protective mechanisms interacts synergistically with the hyperthermia of exercise to perhaps explain heat stroke cases reported in low-risk populations performing routine activities. Importantly, we question the "traditional" notion that high core temperature is the critical mediator of exercise performance degradation and heat stroke. Published 2011. This article is a U.S. Government work and is in the public domain in the USA. PMID:23733692

  12. Intra-plastid protein trafficking; how plant cells adapted prokaryotic mechanisms to the eukaryotic condition

    PubMed Central

    Celedon, Jose M.; Cline, Kenneth

    2012-01-01

    Protein trafficking and localization in plastids involves a complex interplay between ancient (prokaryotic) and novel (eukaryotic) translocases and targeting machineries. During evolution, ancient systems acquired new functions and novel translocation machineries were developed to facilitate the correct localization of nuclear encoded proteins targeted to the chloroplast. Because of its post-translational nature, targeting and integration of membrane proteins posed the biggest challenge to the organelle to avoid aggregation in the aqueous compartments. Soluble proteins faced a different kind of problem since some had to be transported across three membranes to reach their destination. Early studies suggested that chloroplasts addressed these issues by adapting ancient-prokaryotic machineries and integrating them with novel-eukaryotic systems, a process called ‘conservative sorting’. In the last decade, detailed biochemical, genetic, and structural studies have unraveled the mechanisms of protein targeting and localization in chloroplasts, suggesting a highly integrated scheme where ancient and novel systems collaborate at different stages of the process. In this review we focus on the differences and similarities between chloroplast ancestral translocases and their prokaryotic relatives to highlight known modifications that adapted them to the eukaryotic situation. PMID:22750312

  13. Integrated physiological mechanisms of exercise performance, adaptation, and maladaptation to heat stress.

    PubMed

    Sawka, Michael N; Leon, Lisa R; Montain, Scott J; Sonna, Larry A

    2011-10-01

    This article emphasizes significant recent advances regarding heat stress and its impact on exercise performance, adaptations, fluid electrolyte imbalances, and pathophysiology. During exercise-heat stress, the physiological burden of supporting high skin blood flow and high sweating rates can impose considerable cardiovascular strain and initiate a cascade of pathophysiological events leading to heat stroke. We examine the association between heat stress, particularly high skin temperature, on diminishing cardiovascular/aerobic reserves as well as increasing relative intensity and perceptual cues that degrade aerobic exercise performance. We discuss novel systemic (heat acclimation) and cellular (acquired thermal tolerance) adaptations that improve performance in hot and temperate environments and protect organs from heat stroke as well as other dissimilar stresses. We delineate how heat stroke evolves from gut underperfusion/ischemia causing endotoxin release or the release of mitochondrial DNA fragments in response to cell necrosis, to mediate a systemic inflammatory syndrome inducing coagulopathies, immune dysfunction, cytokine modulation, and multiorgan damage and failure. We discuss how an inflammatory response that induces simultaneous fever and/or prior exposure to a pathogen (e.g., viral infection) that deactivates molecular protective mechanisms interacts synergistically with the hyperthermia of exercise to perhaps explain heat stroke cases reported in low-risk populations performing routine activities. Importantly, we question the "traditional" notion that high core temperature is the critical mediator of exercise performance degradation and heat stroke. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

  14. Self-Adaptive Image Reconstruction Inspired by Insect Compound Eye Mechanism

    PubMed Central

    Zhang, Jiahua; Shi, Aiye; Wang, Xin; Bian, Linjie; Huang, Fengchen; Xu, Lizhong

    2012-01-01

    Inspired by the mechanism of imaging and adaptation to luminosity in insect compound eyes (ICE), we propose an ICE-based adaptive reconstruction method (ARM-ICE), which can adjust the sampling vision field of image according to the environment light intensity. The target scene can be compressive, sampled independently with multichannel through ARM-ICE. Meanwhile, ARM-ICE can regulate the visual field of sampling to control imaging according to the environment light intensity. Based on the compressed sensing joint sparse model (JSM-1), we establish an information processing system of ARM-ICE. The simulation of a four-channel ARM-ICE system shows that the new method improves the peak signal-to-noise ratio (PSNR) and resolution of the reconstructed target scene under two different cases of light intensity. Furthermore, there is no distinct block effect in the result, and the edge of the reconstructed image is smoother than that obtained by the other two reconstruction methods in this work. PMID:23365615

  15. Non-Invasive Investigation of Bone Adaptation in Humans to Mechanical Loading

    NASA Technical Reports Server (NTRS)

    Whalen, R.

    1999-01-01

    Experimental studies have identified peak cyclic forces, number of loading cycles, and loading rate as contributors to the regulation of bone metabolism. We have proposed a theoretical model that relates bone density to a mechanical stimulus derived from average daily cumulative peak cyclic 'effective' tissue stresses. In order to develop a non-invasive experimental model to test the theoretical model we need to: (1) monitor daily cumulative loading on a bone, (2) compute the internal stress state(s) resulting from the imposed loading, and (3) image volumetric bone density accurately, precisely, and reproducibly within small contiguous volumes throughout the bone. We have chosen the calcaneus (heel) as an experimental model bone site because it is loaded by ligament, tendon and joint contact forces in equilibrium with daily ground reaction forces that we can measure; it is a peripheral bone site and therefore more easily and accurately imaged with computed tomography; it is composed primarily of cancellous bone; and it is a relevant site for monitoring bone loss and adaptation in astronauts and the general population. This paper presents an overview of our recent advances in the areas of monitoring daily ground reaction forces, biomechanical modeling of the forces on the calcaneus during gait, mathematical modeling of calcaneal bone adaptation in response to cumulative daily activity, accurate and precise imaging of the calcaneus with quantitative computed tomography (QCT), and application to long duration space flight.

  16. Intra-plastid protein trafficking: how plant cells adapted prokaryotic mechanisms to the eukaryotic condition.

    PubMed

    Celedon, Jose M; Cline, Kenneth

    2013-02-01

    Protein trafficking and localization in plastids involve a complex interplay between ancient (prokaryotic) and novel (eukaryotic) translocases and targeting machineries. During evolution, ancient systems acquired new functions and novel translocation machineries were developed to facilitate the correct localization of nuclear encoded proteins targeted to the chloroplast. Because of its post-translational nature, targeting and integration of membrane proteins posed the biggest challenge to the organelle to avoid aggregation in the aqueous compartments. Soluble proteins faced a different kind of problem since some had to be transported across three membranes to reach their destination. Early studies suggested that chloroplasts addressed these issues by adapting ancient-prokaryotic machineries and integrating them with novel-eukaryotic systems, a process called 'conservative sorting'. In the last decade, detailed biochemical, genetic, and structural studies have unraveled the mechanisms of protein targeting and localization in chloroplasts, suggesting a highly integrated scheme where ancient and novel systems collaborate at different stages of the process. In this review we focus on the differences and similarities between chloroplast ancestral translocases and their prokaryotic relatives to highlight known modifications that adapted them to the eukaryotic situation. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.

  17. Effects of mechanical forces on maintenance and adaptation of form in trabecular bone

    NASA Astrophysics Data System (ADS)

    Huiskes, Rik; Ruimerman, Ronald; van Lenthe, G. Harry; Janssen, Jan D.

    2000-06-01

    The architecture of trabecular bone, the porous bone found in the spine and at articulating joints, provides the requirements for optimal load transfer, by pairing suitable strength and stiffness to minimal weight according to rules of mathematical design. But, as it is unlikely that the architecture is fully pre-programmed in the genes, how are the bone cells informed about these rules, which so obviously dictate architecture? A relationship exists between bone architecture and mechanical usage-while strenuous exercise increases bone mass, disuse, as in microgravity and inactivity, reduces it. Bone resorption cells (osteoclasts) and bone formation cells (osteoblasts) normally balance bone mass in a coupled homeostatic process of remodelling, which renews some 25% of trabecular bone volume per year. Here we present a computational model of the metabolic process in bone that confirms that cell coupling is governed by feedback from mechanical load transfer.This model can explain the emergence and maintenance of trabecular architecture as an optimal mechanical structure, as well as its adaptation to alternative external loads.

  18. [Strategies and mechanisms of soil springtails in adapting lower temperature environment: research progress].

    PubMed

    Liu, Jing; Wang, Yun-Biao; Wu, Dong-Hui

    2012-12-01

    Low temperature and drought are the main environmental factors threatening the animals living in arctic area and cold temperate regions. To adapt the severe environment, the animals should adopt appropriate strategies. As a group of arthopods with freeze-avoiding strategy, soil springtails have the similar ecological mechanisms and modes of cold resistance/tolerance as insects, manifesting in the cold acclimation and drought tolerance to decrease the damage of ice crystal formation. During cold acclimation, there are a rapid increase of glycerol, a rapid decrease of fucose and glucose, and the production of anti-freeze proteins (AFP) , and exists the inter-transformation of different kinds of lipids to improve the flow of cell membrane to protect the cell from low temperature injury. In addition, soil springtails have their own specific modes and mechanisms to tolerate low temperature stress, mainly the vertical migration under the protection of snow cover and the excretion of ice nucleator from haemolymph, illustrating that it's of significance to research the cryobiology of soil springtails. This paper summarized the modes and mechanisms of soil springtails in tolerating low temperature environment, reviewed the research progress on the eco-physiology of the springtails, discussed the existing problems of the researches on the low temperature tolerance of the springtails, and prospected the research directions of the springtails low temperature ecology under the background of global change. PMID:23479899

  19. Mechano-adaptive sensory mechanism of α-catenin under tension

    PubMed Central

    Maki, Koichiro; Han, Sung-Woong; Hirano, Yoshinori; Yonemura, Shigenobu; Hakoshima, Toshio; Adachi, Taiji

    2016-01-01

    The contractile forces in individual cells drive the tissue processes, such as morphogenesis and wound healing, and maintain tissue integrity. In these processes, α-catenin molecule acts as a tension sensor at cadherin-based adherens junctions (AJs), accelerating the positive feedback of intercellular tension. Under tension, α-catenin is activated to recruit vinculin, which recruits actin filaments to AJs. In this study, we revealed how α-catenin retains its activated state while avoiding unfolding under tension. Using single-molecule force spectroscopy employing atomic force microscopy (AFM), we found that mechanically activated α-catenin fragment had higher mechanical stability than a non-activated fragment. The results of our experiments using mutated and segmented fragments showed that the key intramolecular interactions acted as a conformational switch. We also found that the conformation of α-catenin was reinforced by vinculin binding. We demonstrate that α-catenin adaptively changes its conformation under tension to a stable intermediate state, binds to vinculin, and finally settles into a more stable state reinforced by vinculin binding. Our data suggest that the plastic characteristics of α-catenin, revealed in response to both mechanical and biochemical cues, enable the functional-structural dynamics at the cellular and tissue levels. PMID:27109499

  20. Genomic Mechanisms Accounting for the Adaptation to Parasitism in Nematode-Trapping Fungi

    PubMed Central

    Meerupati, Tejashwari; Andersson, Karl-Magnus; Friman, Eva; Kumar, Dharmendra; Tunlid, Anders; Ahrén, Dag

    2013-01-01

    Orbiliomycetes is one of the earliest diverging branches of the filamentous ascomycetes. The class contains nematode-trapping fungi that form unique infection structures, called traps, to capture and kill free-living nematodes. The traps have evolved differently along several lineages and include adhesive traps (knobs, nets or branches) and constricting rings. We show, by genome sequencing of the knob-forming species Monacrosporium haptotylum and comparison with the net-forming species Arthrobotrys oligospora, that two genomic mechanisms are likely to have been important for the adaptation to parasitism in these fungi. Firstly, the expansion of protein domain families and the large number of species-specific genes indicated that gene duplication followed by functional diversification had a major role in the evolution of the nematode-trapping fungi. Gene expression indicated that many of these genes are important for pathogenicity. Secondly, gene expression of orthologs between the two fungi during infection indicated that differential regulation was an important mechanism for the evolution of parasitism in nematode-trapping fungi. Many of the highly expressed and highly upregulated M. haptotylum transcripts during the early stages of nematode infection were species-specific and encoded small secreted proteins (SSPs) that were affected by repeat-induced point mutations (RIP). An active RIP mechanism was revealed by lack of repeats, dinucleotide bias in repeats and genes, low proportion of recent gene duplicates, and reduction of recent gene family expansions. The high expression and rapid divergence of SSPs indicate a striking similarity in the infection mechanisms of nematode-trapping fungi and plant and insect pathogens from the crown groups of the filamentous ascomycetes (Pezizomycotina). The patterns of gene family expansions in the nematode-trapping fungi were more similar to plant pathogens than to insect and animal pathogens. The observation of RIP activity

  1. Genomic mechanisms accounting for the adaptation to parasitism in nematode-trapping fungi.

    PubMed

    Meerupati, Tejashwari; Andersson, Karl-Magnus; Friman, Eva; Kumar, Dharmendra; Tunlid, Anders; Ahrén, Dag

    2013-11-01

    Orbiliomycetes is one of the earliest diverging branches of the filamentous ascomycetes. The class contains nematode-trapping fungi that form unique infection structures, called traps, to capture and kill free-living nematodes. The traps have evolved differently along several lineages and include adhesive traps (knobs, nets or branches) and constricting rings. We show, by genome sequencing of the knob-forming species Monacrosporium haptotylum and comparison with the net-forming species Arthrobotrys oligospora, that two genomic mechanisms are likely to have been important for the adaptation to parasitism in these fungi. Firstly, the expansion of protein domain families and the large number of species-specific genes indicated that gene duplication followed by functional diversification had a major role in the evolution of the nematode-trapping fungi. Gene expression indicated that many of these genes are important for pathogenicity. Secondly, gene expression of orthologs between the two fungi during infection indicated that differential regulation was an important mechanism for the evolution of parasitism in nematode-trapping fungi. Many of the highly expressed and highly upregulated M. haptotylum transcripts during the early stages of nematode infection were species-specific and encoded small secreted proteins (SSPs) that were affected by repeat-induced point mutations (RIP). An active RIP mechanism was revealed by lack of repeats, dinucleotide bias in repeats and genes, low proportion of recent gene duplicates, and reduction of recent gene family expansions. The high expression and rapid divergence of SSPs indicate a striking similarity in the infection mechanisms of nematode-trapping fungi and plant and insect pathogens from the crown groups of the filamentous ascomycetes (Pezizomycotina). The patterns of gene family expansions in the nematode-trapping fungi were more similar to plant pathogens than to insect and animal pathogens. The observation of RIP activity

  2. Grid coupling mechanism in the semi-implicit adaptive Multi-Level Multi-Domain method

    NASA Astrophysics Data System (ADS)

    Innocenti, M. E.; Tronci, C.; Markidis, S.; Lapenta, G.

    2016-05-01

    The Multi-Level Multi-Domain (MLMD) method is a semi-implicit adaptive method for Particle-In-Cell plasma simulations. It has been demonstrated in the past in simulations of Maxwellian plasmas, electrostatic and electromagnetic instabilities, plasma expansion in vacuum, magnetic reconnection [1, 2, 3]. In multiple occasions, it has been commented on the coupling between the coarse and the refined grid solutions. The coupling mechanism itself, however, has never been explored in depth. Here, we investigate the theoretical bases of grid coupling in the MLMD system. We obtain an evolution law for the electric field solution in the overlap area of the MLMD system which highlights a dependance on the densities and currents from both the coarse and the refined grid, rather than from the coarse grid alone: grid coupling is obtained via densities and currents.

  3. Ca2+-dependent regulations and signaling in skeletal muscle: from electro-mechanical coupling to adaptation.

    PubMed

    Gehlert, Sebastian; Bloch, Wilhelm; Suhr, Frank

    2015-01-05

    Calcium (Ca2+) plays a pivotal role in almost all cellular processes and ensures the functionality of an organism. In skeletal muscle fibers, Ca(2+) is critically involved in the innervation of skeletal muscle fibers that results in the exertion of an action potential along the muscle fiber membrane, the prerequisite for skeletal muscle contraction. Furthermore and among others, Ca(2+) regulates also intracellular processes, such as myosin-actin cross bridging, protein synthesis, protein degradation and fiber type shifting by the control of Ca(2+)-sensitive proteases and transcription factors, as well as mitochondrial adaptations, plasticity and respiration. These data highlight the overwhelming significance of Ca(2+) ions for the integrity of skeletal muscle tissue. In this review, we address the major functions of Ca(2+) ions in adult muscle but also highlight recent findings of critical Ca(2+)-dependent mechanisms essential for skeletal muscle-regulation and maintenance.

  4. Ca2+-Dependent Regulations and Signaling in Skeletal Muscle: From Electro-Mechanical Coupling to Adaptation

    PubMed Central

    Gehlert, Sebastian; Bloch, Wilhelm; Suhr, Frank

    2015-01-01

    Calcium (Ca2+) plays a pivotal role in almost all cellular processes and ensures the functionality of an organism. In skeletal muscle fibers, Ca2+ is critically involved in the innervation of skeletal muscle fibers that results in the exertion of an action potential along the muscle fiber membrane, the prerequisite for skeletal muscle contraction. Furthermore and among others, Ca2+ regulates also intracellular processes, such as myosin-actin cross bridging, protein synthesis, protein degradation and fiber type shifting by the control of Ca2+-sensitive proteases and transcription factors, as well as mitochondrial adaptations, plasticity and respiration. These data highlight the overwhelming significance of Ca2+ ions for the integrity of skeletal muscle tissue. In this review, we address the major functions of Ca2+ ions in adult muscle but also highlight recent findings of critical Ca2+-dependent mechanisms essential for skeletal muscle-regulation and maintenance. PMID:25569087

  5. Mechanisms and implications of adaptive immune responses after traumatic spinal cord injury

    PubMed Central

    Ankeny, Daniel P.; Popovich, Phillip G.

    2009-01-01

    Traumatic spinal cord injury (SCI) in mammals causes widespread glial activation and recruitment to the CNS of innate (e.g., neutrophils, monocytes) and adaptive (e.g., T and B lymphocytes) immune cells. To date, most studies have sought to understand or manipulate the post-traumatic functions of astrocytes, microglia, neutrophils or monocytes. Significantly less is known about the consequences of SCI-induced lymphocyte activation. Yet, emerging data suggest that T and B cells are activated by SCI and play significant roles in shaping post-traumatic inflammation and downstream cascades of neurodegeneration and repair. Here, we provide neurobiologists with a timely review of the mechanisms and implications of SCI-induced lymphocyte activation, including a discussion of different experimental strategies that have been designed to manipulate lymphocyte function for therapeutic gain. PMID:18674593

  6. Ca2+-dependent regulations and signaling in skeletal muscle: from electro-mechanical coupling to adaptation.

    PubMed

    Gehlert, Sebastian; Bloch, Wilhelm; Suhr, Frank

    2015-01-01

    Calcium (Ca2+) plays a pivotal role in almost all cellular processes and ensures the functionality of an organism. In skeletal muscle fibers, Ca(2+) is critically involved in the innervation of skeletal muscle fibers that results in the exertion of an action potential along the muscle fiber membrane, the prerequisite for skeletal muscle contraction. Furthermore and among others, Ca(2+) regulates also intracellular processes, such as myosin-actin cross bridging, protein synthesis, protein degradation and fiber type shifting by the control of Ca(2+)-sensitive proteases and transcription factors, as well as mitochondrial adaptations, plasticity and respiration. These data highlight the overwhelming significance of Ca(2+) ions for the integrity of skeletal muscle tissue. In this review, we address the major functions of Ca(2+) ions in adult muscle but also highlight recent findings of critical Ca(2+)-dependent mechanisms essential for skeletal muscle-regulation and maintenance. PMID:25569087

  7. Priming of antiherbivore defensive responses in plants.

    PubMed

    Kim, Jinwon; Felton, Gary W

    2013-06-01

    Defense priming is defined as increased readiness of defense induction. A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses, both biotic and abiotic, and upon the following stimulus, induce defenses more quickly and strongly. For instance, some plants previously exposed to herbivore-inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger defense activation and enhanced insect resistance when challenged with secondary insect feeding. Research on priming of antiherbivore defense has been limited to the HIPV-mediated mechanism until recently, but significant advances were made in the past three years, including non-HIPV-mediated defense priming, epigenetic modifications as the molecular mechanism of priming, and others. It is timely to consider the advances in research on defense priming in the plant-insect interactions.

  8. Time Course of Pathogenic and Adaptation Mechanisms in Cystinotic Mouse Kidneys

    PubMed Central

    Gaide Chevronnay, Héloïse P.; Janssens, Virginie; Van Der Smissen, Patrick; N’Kuli, Francisca; Nevo, Nathalie; Guiot, Yves; Levtchenko, Elena; Marbaix, Etienne; Pierreux, Christophe E.; Cherqui, Stéphanie; Antignac, Corinne; Courtoy, Pierre J.

    2014-01-01

    Cystinosis, a main cause of Fanconi syndrome, is reproduced in congenic C57BL/6 cystinosin knockout (KO) mice. To identify the sequence of pathogenic and adaptation mechanisms of nephropathic cystinosis, we defined the onset of Fanconi syndrome in KO mice between 3 and 6 months of age and analyzed the correlation with structural and functional changes in proximal tubular cells (PTCs), with focus on endocytosis of ultrafiltrated disulfide-rich proteins as a key source of cystine. Despite considerable variation between mice at the same age, typical event sequences were delineated. At the cellular level, amorphous lysosomal inclusions preceded cystine crystals and eventual atrophy without crystals. At the nephron level, lesions started at the glomerulotubular junction and then extended distally. In situ hybridization and immunofluorescence revealed progressive loss of expression of megalin, cubilin, sodium-glucose cotransporter 2, and type IIa sodium-dependent phosphate cotransporter, suggesting apical dedifferentiation accounting for Fanconi syndrome before atrophy. Injection of labeled proteins revealed that defective endocytosis in S1 PTCs led to partial compensatory uptake by S3 PTCs, suggesting displacement of endocytic load and injury by disulfide-rich cargo. Increased PTC apoptosis allowed luminal shedding of cystine crystals and was partially compensated for by tubular proliferation. We conclude that lysosomal storage triggered by soluble cystine accumulation induces apical PTC dedifferentiation, which causes transfer of the harmful load of disulfide-rich proteins to more distal cells, possibly explaining longitudinal progression of swan-neck lesions. Furthermore, our results suggest that subsequent adaptation mechanisms include lysosomal clearance of free and crystalline cystine into urine and ongoing tissue repair. PMID:24525030

  9. Adaptive response of bacteria: Multiple hurdles, cross-tolerance and tools to illustrate underlying mechanisms

    NASA Astrophysics Data System (ADS)

    Paramythiotis, Spyridon; Skandamis, Panagiotis N.

    2015-01-01

    A basic principle in the bacterial resistance against lethal stresses is that exposure of microbial cells to a sublethal hurdle (e.g., pH 5.0, 3% NaCl, or 48°C) may induce resistance to lethal level of the same or different stress. The latter is called "cross-tolerance" and the bacteria experiencing such situations are termed "stress-hardened". The majority of scientific reports on the adaptive responses of bacteria to stresses have recently addressed the need to elucidate the underlying mechanisms controlling bacterial stress response. This in turn, will assist in the efficient application of the multiple hurdle approach, e.g., by selecting specific sanitizers, combining stress treatments or antimicrobials, especially in mild processing, against specific cellular targets, eliminating the possibility of the development of stress adapted cells. Common scientific approaches for studying the link between phenotype (e.g., inactivation, survival, or growth) and physiology is the assessment of global transcriptional changes (up- or down-regulation) or those of certain genes, as well as of proteins involved in certain metabolic pathways, occurring during exposure to stress. This may also be performed in parallel to comparative evaluation of the phenotypic response of wild and mutant strains. The post-genomics research on foodborne pathogens has extended our knowledge beyond their phenotypic behavior and may offer mechanistic insights in the following: (i) the top-down approach (induction), which is the search of the underlying mechanisms (low level) responsible for a specific phenotype based on "-omic" studies; and (ii) the bottom-up approach (deduction), which starts from intracellular level and forms a mechanistic (functional) basis for the cellular response. All these may eventually enable the development of mechanistic microbial models and efficient strategies for controlling survival and growth of pathogens in foods.

  10. Time course of pathogenic and adaptation mechanisms in cystinotic mouse kidneys.

    PubMed

    Gaide Chevronnay, Héloïse P; Janssens, Virginie; Van Der Smissen, Patrick; N'Kuli, Francisca; Nevo, Nathalie; Guiot, Yves; Levtchenko, Elena; Marbaix, Etienne; Pierreux, Christophe E; Cherqui, Stéphanie; Antignac, Corinne; Courtoy, Pierre J

    2014-06-01

    Cystinosis, a main cause of Fanconi syndrome, is reproduced in congenic C57BL/6 cystinosin knockout (KO) mice. To identify the sequence of pathogenic and adaptation mechanisms of nephropathic cystinosis, we defined the onset of Fanconi syndrome in KO mice between 3 and 6 months of age and analyzed the correlation with structural and functional changes in proximal tubular cells (PTCs), with focus on endocytosis of ultrafiltrated disulfide-rich proteins as a key source of cystine. Despite considerable variation between mice at the same age, typical event sequences were delineated. At the cellular level, amorphous lysosomal inclusions preceded cystine crystals and eventual atrophy without crystals. At the nephron level, lesions started at the glomerulotubular junction and then extended distally. In situ hybridization and immunofluorescence revealed progressive loss of expression of megalin, cubilin, sodium-glucose cotransporter 2, and type IIa sodium-dependent phosphate cotransporter, suggesting apical dedifferentiation accounting for Fanconi syndrome before atrophy. Injection of labeled proteins revealed that defective endocytosis in S1 PTCs led to partial compensatory uptake by S3 PTCs, suggesting displacement of endocytic load and injury by disulfide-rich cargo. Increased PTC apoptosis allowed luminal shedding of cystine crystals and was partially compensated for by tubular proliferation. We conclude that lysosomal storage triggered by soluble cystine accumulation induces apical PTC dedifferentiation, which causes transfer of the harmful load of disulfide-rich proteins to more distal cells, possibly explaining longitudinal progression of swan-neck lesions. Furthermore, our results suggest that subsequent adaptation mechanisms include lysosomal clearance of free and crystalline cystine into urine and ongoing tissue repair. PMID:24525030

  11. Comparison of human turning gait with the mechanical performance of lower limb prosthetic transverse rotation adapters.

    PubMed

    Flick, K C; Orendurff, M S; Berge, J S; Segal, A D; Klute, G K

    2005-04-01

    Given the importance of minimizing transverse plane shear stress on soft tissue, several transverse rotational adapters (TRAs) are available for incorporation in lower limb prostheses. This study compares kinetic and kinematic data from human subjects during straight and turning gaits to the mechanical performance of several TRAs. Physiological data were collected from three individuals walking straight and turning at self-selected speeds around a 1 m radius circle. The average peak torques and range of motion for normal subjects while turning were 8.2 Nm and 26 degrees (outside leg), 11.8Nm and 20 degrees (inside leg), and 11.4 Nm and 20 degrees (right leg) during straight gait. Each TRA was mechanically tested without axial loading in a servo-hydraulic material testing system (MTS) over its rotational range at 0.5 dergrees/s and 60 degrees/s. The TRAs with axial compression were also tested at 0.5 degrees/s under a 736N (75kg mass) axial load. Applying these torques to the different TRAs yielded 3 to 35 degrees rotation, depending on the elastomer installed. Some TRAs had nearly constant stiffness, while others stiffened with rotation. The TRAs also varied in their average maximum stiffness from 0.4Nm/degree to 2.7Nm/degrees. Normal subjects exhibit interior vs. exterior asymmetrical torques and displacements; however, only one of the TRAs is designed to allow asymmetrical stiffness, and none have asymmetric ranges. Prosthetists and physicians can use these data to better interpret amputees' qualitative remarks and to prescribe the correct TRA and/or elastomer. This information also forms a basis for further design and development of novel torque absorbing prosthetic adapters.

  12. Dopamine as a potent inducer of cellular glutathione and NAD(P)H:quinone oxidoreductase 1 in PC12 neuronal cells: a potential adaptive mechanism for dopaminergic neuroprotection.

    PubMed

    Jia, Zhenquan; Zhu, Hong; Misra, Bhaba R; Li, Yunbo; Misra, Hara P

    2008-11-01

    Dopamine auto-oxidation and the consequent formation of reactive oxygen species and electrophilic quinone molecules have been implicated in dopaminergic neuronal cell death in Parkinson's disease. We reported here that in PC12 dopaminergic neuronal cells dopamine at noncytotoxic concentrations (50-150 muM) potently induced cellular glutathione (GSH) and the phase 2 enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1), two critical cellular defenses in detoxification of ROS and electrophilic quinone molecules. Incubation of PC12 cells with dopamine also led to a marked increase in the mRNA levels for gamma-glutamylcysteine ligase catalytic subunit (GCLC) and NQO1. In addition, treatment of PC12 cells with dopamine resulted in a significant elevation of GSH content in the mitochondrial compartment. To determine whether treatment with dopamine at noncytotoxic concentrations, which upregulated the cellular defenses could protect the neuronal cells against subsequent lethal oxidative and electrophilic injury, PC12 cells were pretreated with dopamine (150 muM) for 24 h and then exposed to various cytotoxic concentrations of dopamine or 6-hydroxydopamine (6-OHDA). We found that pretreatment of PC12 cells with dopamine at a noncytotoxic concentration led to a remarkable protection against cytotoxicity caused by dopamine or 6-OHDA at lethal concentrations, as detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium reduction assay. In view of the critical roles of GSH and NQO1 in protecting against dopaminergic neuron degeneration, the above findings implicate that upregulation of both GSH and NQO1 by dopamine at noncytotoxic concentrations may serve as an important adaptive mechanism for dopaminergic neuroprotection. PMID:18368484

  13. Proteome changes in tomato fruits prior to visible symptoms of chilling injury are linked to defensive mechanisms, uncoupling of photosynthetic processes and protein degradation machinery.

    PubMed

    Sanchez-Bel, Paloma; Egea, Isabel; Sanchez-Ballesta, María Teresa; Sevillano, Laura; Del Carmen Bolarin, Maria; Flores, Francisco B

    2012-02-01

    A comparative proteomic analysis between tomato fruits stored at chilling and non-chilling temperatures was carried out just before the appearance of visible symptoms of chilling injury. At this stage of the stress period it was possible to discriminate between proteins involved in symptoms and proteins implicated in response. To investigate the changes in the tomato fruit proteome under this specific stressful condition, two-dimensional differential in-gel electrophoresis coupled with spot identification by mass spectrometry was applied. This proteomic approach allowed the identification of differentially expressed proteins which are involved in two main biological functions: (i) defensive mechanisms represented by small heat shock and late embryogenesis proteins; and (ii) reaction to the uncoupling of photosynthetic processes and the protein degradation machinery. One of the first changes observed in chilled fruits is the down-regulation of ATP synthase, 26S proteasome subunit RPN11 and aspartic proteinase, whereas the first responses in order to deal with the stress are mainly multifunctional proteins involved not only in metabolism but also in stress regulation such as glyceraldehyde phosphate dehydrogenase, 2-oxoglutarate dehydrogenase and invertase. In addition, our data seem to indicate a possible candidate to be used as a protein marker for further studies on cold stress: aldose-1-epimerase, which seems to have an important role in low temperature tolerance. PMID:22227396

  14. Identification of soybean MYC2-like transcription factors and overexpression of GmMYC1 could stimulate defense mechanism against common cutworm in transgenic tobacco.

    PubMed

    Wang, Hui; Ding, Changwen; Du, Haiping; Liu, Hailun; Wang, Yongli; Yu, Deyue

    2014-09-01

    MYC2 is a basic helix-loop-helix Leu zipper transcription factor (TF). Here, 22 putative soybean MYC-like TFs were identified bioinformatically. Of these TFs, seven MYC2-like genes without introns were isolated and characterized. All seven GmMYCs displayed transactivation activity in yeast cells. Six genes (excepting GmMYC3) were expressed in the roots, stems, leaves, flowers, and seed wall but not in the developing seeds and up-regulated after insect feeding. The GmMYC1 transgenic tobacco rejected common cutworm (CCW, Spodoptera litura Fabricius) more strongly and lost less leaf area than the control (2.94 ± 2.36 vs 7.84 ± 4.63 cm(2)). The average relative growth rate of CCW feeding on transgenic tobacco leaves was lower than on control tobacco leaves (136 ± 60 vs 271 ± 76 %). These results indicated that GmMYC could stimulate the defense mechanism against insects in plants.

  15. Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value.

    PubMed

    Bloch, Guy; Barnes, Brian M; Gerkema, Menno P; Helm, Barbara

    2013-08-22

    Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles.

  16. Multifractal entropy based adaptive multiwavelet construction and its application for mechanical compound-fault diagnosis

    NASA Astrophysics Data System (ADS)

    He, Shuilong; Chen, Jinglong; Zhou, Zitong; Zi, Yanyang; Wang, Yanxue; Wang, Xiaodong

    2016-08-01

    Compound-fault diagnosis of mechanical equipment is still challenging at present because of its complexity, multiplicity and non-stationarity. In this work, an adaptive redundant multiwavelet packet (ARMP) method is proposed for the compound-fault diagnosis. Multiwavelet transform has two or more base functions and many excellent properties, making it suitable for detecting all the features of compound-fault simultaneously. However, on the other hand, the fixed basis function used in multiwavelet transform may decrease the accuracy of fault extraction; what's more, the multi-resolution analysis of multiwavelet transform in low frequency band may also leave out the useful features. Thus, the minimum sum of normalized multifractal entropy is adopted as the optimization criteria for the proposed ARMP method, while the relative energy ratio of the characteristic frequency is utilized as an effective way in automatically selecting the sensitive frequency bands. Then, The ARMP technique combined with Hilbert transform demodulation analysis is then applied to detect the compound-fault of bevel gearbox and planetary gearbox. The results verify that the proposed method can effectively identify and detect the compound-fault of mechanical equipment.

  17. Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value

    PubMed Central

    Bloch, Guy; Barnes, Brian M.; Gerkema, Menno P.; Helm, Barbara

    2013-01-01

    Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles. PMID:23825202

  18. Do common mechanisms of adaptation mediate color discrimination and appearance? Uniform backgrounds.

    PubMed

    Hillis, James M; Brainard, David H

    2005-10-01

    Color vision is useful for detecting surface boundaries and identifying objects. Are the signals used to perform these two functions processed by common mechanisms, or has the visual system optimized its processing separately for each task? We measured the effect of mean chromaticity and luminance on color discriminability and on color appearance under well-matched stimulus conditions. In the discrimination experiments, a pedestal spot was presented in one interval and a pedestal + test in a second. Observers indicated which interval contained the test. In the appearance experiments, observers matched the appearance of test spots across a change in background. We analyzed the data using a variant of Fechner's proposal, that the rate of apparent stimulus change is proportional to visual sensitivity. We found that saturating visual response functions together with a model of adaptation that included multiplicative gain control and a subtractive term accounted for data from both tasks. This result suggests that effects of the contexts we studied on color appearance and discriminability are controlled by the same underlying mechanism.

  19. Physiological and genetic control mechanisms for plant adaptation to high temperature and elevated CO2

    SciTech Connect

    Zeiger, Eduardo

    2001-02-01

    Acclimations of the stomatal response to CO2 were characterized. Stomata from the model plant used, Vicia faba, are very sensitive to ambient CO2 when grown in growth chambers as compared to stomata from green house grown leaves. The different CO2 sensitivities of growth chamber and green house grown guard cells was confirmed by reciprocal transfer experiments. Stomata acclimated to their new environment and acquired the CO2 sensitivity typical of that environment. A mechanism for CO2 sensing was also characterized. Results show that CO2 concentration alters the concentration of zeaxanthin in the guard cell chloroplast, thus modifying the light response of the guard cells. This mechanism accounts for the well characterized interactions of light and CO2 in the stomatal responses. The xanthophyll cycle in the stomata of the facultative CAM plant, Mesembryanthemum crystallinum, was characterized. In the C3 mode, zeaxanthin is formed in the light and stomata open. Upon induction of the CAM mode, zeaxanthin synthesis is blocked and stomata no longer respond to light. These results implicate the regulation of the xanthophyll cycle of guard cells in the CAM adaptation.

  20. Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value.

    PubMed

    Bloch, Guy; Barnes, Brian M; Gerkema, Menno P; Helm, Barbara

    2013-08-22

    Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles. PMID:23825202

  1. Evolution of the fruit endocarp: molecular mechanisms underlying adaptations in seed protection and dispersal strategies

    PubMed Central

    Dardick, Chris; Callahan, Ann M.

    2014-01-01

    Plant evolution is largely driven by adaptations in seed protection and dispersal strategies that allow diversification into new niches. This is evident by the tremendous variation in flowering and fruiting structures present both across and within different plant lineages. Within a single plant family a staggering variety of fruit types can be found such as fleshy fruits including berries, pomes, and drupes and dry fruit structures like achenes, capsules, and follicles. What are the evolutionary mechanisms that enable such dramatic shifts to occur in a relatively short period of time? This remains a fundamental question of plant biology today. On the surface it seems that these extreme differences in form and function must be the consequence of very different developmental programs that require unique sets of genes. Yet as we begin to decipher the molecular and genetic basis underlying fruit form it is becoming apparent that simple genetic changes in key developmental regulatory genes can have profound anatomical effects. In this review, we discuss recent advances in understanding the molecular mechanisms of fruit endocarp tissue differentiation that have contributed to species diversification within three plant lineages. PMID:25009543

  2. Secured network sensor-based defense system

    NASA Astrophysics Data System (ADS)

    Wei, Sixiao; Shen, Dan; Ge, Linqiang; Yu, Wei; Blasch, Erik P.; Pham, Khanh D.; Chen, Genshe

    2015-05-01

    Network sensor-based defense (NSD) systems have been widely used to defend against cyber threats. Nonetheless, if the adversary finds ways to identify the location of monitor sensors, the effectiveness of NSD systems can be reduced. In this paper, we propose both temporal and spatial perturbation based defense mechanisms to secure NSD systems and make the monitor sensor invisible to the adversary. The temporal-perturbation based defense manipulates the timing information of published data so that the probability of successfully recognizing monitor sensors can be reduced. The spatial-perturbation based defense dynamically redeploys monitor sensors in the network so that the adversary cannot obtain the complete information to recognize all of the monitor sensors. We carried out experiments using real-world traffic traces to evaluate the effectiveness of our proposed defense mechanisms. Our data shows that our proposed defense mechanisms can reduce the attack accuracy of recognizing detection sensors.

  3. Evidence for Retromutagenesis as a Mechanism for Adaptive Mutation in Escherichia coli

    PubMed Central

    Morreall, Jordan; Kim, Alice; Liu, Yuan; Degtyareva, Natalya; Weiss, Bernard; Doetsch, Paul W.

    2015-01-01

    Adaptive mutation refers to the continuous outgrowth of new mutants from a non-dividing cell population during selection, in apparent violation of the neo-Darwinian principle that mutation precedes selection. One explanation is that of retromutagenesis, in which a DNA lesion causes a transcriptional mutation that yields a mutant protein, allowing escape from selection. This enables a round of DNA replication that establishes heritability. Because the model requires that gene expression precedes DNA replication, it predicts that during selection, new mutants will arise from damage only to the transcribed DNA strand. As a test, we used a lacZ amber mutant of Escherichia coli that can revert by nitrous acid-induced deamination of adenine residues on either strand of the TAG stop codon, each causing different DNA mutations. When stationary-phase, mutagenized cells were grown in rich broth before being plated on lactose-selective media, only non-transcribed strand mutations appeared in the revertants. This result was consistent with the known high sensitivity to deamination of the single-stranded DNA in a transcription bubble, and it provided an important control because it demonstrated that the genetic system we would use to detect transcribed-strand mutations could also detect a bias toward the non-transcribed strand. When residual lacZ transcription was blocked beforehand by catabolite repression, both strands were mutated about equally, but if revertants were selected immediately after nitrous acid exposure, transcribed-strand mutations predominated among the revertants, implicating retromutagenesis as the mechanism. This result was not affected by gene orientation. Retromutagenesis is apt to be a universal method of evolutionary adaptation, which enables the emergence of new mutants from mutations acquired during counterselection rather than beforehand, and it may have roles in processes as diverse as the development of antibiotic resistance and neoplasia. PMID

  4. Evidence for Retromutagenesis as a Mechanism for Adaptive Mutation in Escherichia coli.

    PubMed

    Morreall, Jordan; Kim, Alice; Liu, Yuan; Degtyareva, Natalya; Weiss, Bernard; Doetsch, Paul W

    2015-08-01

    Adaptive mutation refers to the continuous outgrowth of new mutants from a non-dividing cell population during selection, in apparent violation of the neo-Darwinian principle that mutation precedes selection. One explanation is that of retromutagenesis, in which a DNA lesion causes a transcriptional mutation that yields a mutant protein, allowing escape from selection. This enables a round of DNA replication that establishes heritability. Because the model requires that gene expression precedes DNA replication, it predicts that during selection, new mutants will arise from damage only to the transcribed DNA strand. As a test, we used a lacZ amber mutant of Escherichia coli that can revert by nitrous acid-induced deamination of adenine residues on either strand of the TAG stop codon, each causing different DNA mutations. When stationary-phase, mutagenized cells were grown in rich broth before being plated on lactose-selective media, only non-transcribed strand mutations appeared in the revertants. This result was consistent with the known high sensitivity to deamination of the single-stranded DNA in a transcription bubble, and it provided an important control because it demonstrated that the genetic system we would use to detect transcribed-strand mutations could also detect a bias toward the non-transcribed strand. When residual lacZ transcription was blocked beforehand by catabolite repression, both strands were mutated about equally, but if revertants were selected immediately after nitrous acid exposure, transcribed-strand mutations predominated among the revertants, implicating retromutagenesis as the mechanism. This result was not affected by gene orientation. Retromutagenesis is apt to be a universal method of evolutionary adaptation, which enables the emergence of new mutants from mutations acquired during counterselection rather than beforehand, and it may have roles in processes as diverse as the development of antibiotic resistance and neoplasia. PMID

  5. Structures and Mechanisms Design Concepts for Adaptive Deployable Entry Placement Technology

    NASA Technical Reports Server (NTRS)

    Yount, Bryan C.; Arnold, James O.; Gage, Peter J.; Mockelman, Jeffrey; Venkatapathy, Ethiraj

    2012-01-01

    System studies have shown that large deployable aerodynamic decelerators such as the Adaptive Deployable Entry and Placement Technology (ADEPT) concept can revolutionize future robotic and human exploration missions involving atmospheric entry, descent and landing by significantly reducing the maximum heating rate, total heat load, and deceleration loads experienced by the spacecraft during entry [1-3]. ADEPT and the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) [4] share the approach of stowing the entry system in the shroud of the launch vehicle and deploying it to a much larger diameter prior to entry. The ADEPT concept provides a low ballistic coefficient for planetary entry by employing an umbrella-like deployable structure consisting of ribs, struts and a fabric cover that form an aerodynamic decelerator capable of undergoing hypersonic flight. The ADEPT "skin" is a 3-D woven carbon cloth that serves as a thermal protection system (TPS) and as a structural surface that transfers aerodynamic forces to the underlying ribs [5]. This paper focuses on design activities associated with integrating ADEPT components (cloth, ribs, struts and mechanisms) into a system that can function across all configurations and environments of a typical mission concept: stowed during launch, in-space deployment, entry, descent, parachute deployment and separation from the landing payload. The baseline structures and mechanisms were selected via trade studies conducted during the summer and fall of 2012. They are now being incorporated into the design of a ground test article (GTA) that will be fabricated in 2013. It will be used to evaluate retention of the stowed configuration in a launch environment, mechanism operation for release, deployment and locking, and static strength of the deployed decelerator. Of particular interest are the carbon cloth interfaces, underlying hot structure, (Advanced Carbon- Carbon ribs) and other structural components (nose cap, struts, and

  6. Mechanisms underlying the early phase of spike frequency adaptation in mouse spinal motoneurones.

    PubMed

    Miles, G B; Dai, Y; Brownstone, R M

    2005-07-15

    Spike frequency adaptation (SFA) is a fundamental property of repetitive firing in motoneurones (MNs). Early SFA (occurring over several hundred milliseconds) is thought to be important in the initiation of muscular contraction. To date the mechanisms underlying SFA in spinal MNs remain unclear. In the present study, we used both whole-cell patch-clamp recordings of MNs in lumbar spinal cord slices prepared from motor functionally mature mice and computer modelling of spinal MNs to investigate the mechanisms underlying SFA. Pharmacological blocking agents applied during whole-cell recordings in current-clamp mode demonstrated that the medium AHP conductance (apamin), BK-type Ca2+ -dependent K+ channels (iberiotoxin), voltage-activated Ca2+ channels (CdCl2), M-current (linopirdine) and persistent Na+ currents (riluzole) are all unnecessary for SFA. Measurements of Na+ channel availability including action potential amplitude, action potential threshold and maximum depolarization rate of the action potential were found to correlate with instantaneous firing frequency suggesting that the availability of fast, inactivating Na+ channels is involved in SFA. Characterization of this Na+ conductance in voltage-clamp mode demonstrated that it undergoes slow inactivation with a time course similar to that of SFA. When experimentally measured parameters for the fast, inactivating Na+ conductance (including slow inactivation) were incorporated into a MN model, SFA could be faithfully reproduced. The removal of slow inactivation from this model was sufficient to remove SFA. These data indicate that slow inactivation of the fast, inactivating Na+ conductance is likely to be the key mechanism underlying early SFA in spinal MNs.

  7. Ultrastructural and biochemical characterization of mechanically adaptable collagenous structures in the edible sea urchin Paracentrotus lividus.

    PubMed

    Barbaglio, Alice; Tricarico, Serena; Ribeiro, Ana R; Di Benedetto, Cristiano; Barbato, Marta; Dessì, Desirèe; Fugnanesi, Valeria; Magni, Stefano; Mosca, Fabio; Sugni, Michela; Bonasoro, Francesco; Barbosa, Mario A; Wilkie, Iain C; Candia Carnevali, M Daniela

    2015-06-01

    The viscoelastic properties of vertebrate connective tissues rarely undergo significant changes within physiological timescales, the only major exception being the reversible destiffening of the mammalian uterine cervix at the end of pregnancy. In contrast to this, the connective tissues of echinoderms (sea urchins, starfish, sea cucumbers, etc.) can switch reversibly between stiff and compliant conditions in timescales of around a second to minutes. Elucidation of the molecular mechanism underlying such mutability has implications for the zoological, ecological and evolutionary field. Important information could also arise for veterinary and biomedical sciences, particularly regarding the pathological plasticization or stiffening of connective tissue structures. In the present investigation we analyzed aspects of the ultrastructure and biochemistry in two representative models, the compass depressor ligament and the peristomial membrane of the edible sea urchin Paracentrotus lividus, compared in three different mechanical states. The results provide further evidence that the mechanical adaptability of echinoderm connective tissues does not necessarily imply changes in the collagen fibrils themselves. The higher glycosaminoglycan (GAG) content registered in the peristomial membrane with respect to the compass depressor ligament suggests a diverse role of these molecules in the two mutable collagenous tissues. The possible involvement of GAG in the mutability phenomenon will need further clarification. During the shift from a compliant to a standard condition, significant changes in GAG content were detected only in the compass depressor ligament. Similarities in terms of ultrastructure (collagen fibrillar assembling) and biochemistry (two alpha chains) were found between the two models and mammalian collagen. Nevertheless, differences in collagen immunoreactivity, alpha chain migration on SDS-PAGE and BLAST alignment highlighted the uniqueness of sea urchin

  8. Defense Mechanisms of Conifers 1

    PubMed Central

    Lewinsohn, Efraim; Gijzen, Mark; Savage, Thomas J.; Croteau, Rodney

    1991-01-01

    Cell-free extracts from Pinus ponderosa Lawson (ponderosa pine) and Pinus sylvestris L. (Scotch pine) wood exhibited high levels of monoterpene synthase (cyclase) activity, whereas bark extracts of these species contained no detectable activity, and they inhibited cyclase activity when added to extracts from wood, unless polyvinylpyrrolidone was included in the preparation. The molecular mass of the polyvinylpyrrolidone added was of little consequence; however, polyvinylpolypyrrolidone (a cross-linked insoluble form of the polymer) was ineffective in protecting enzyme activity. Based on these observations, methods were developed for the efficient extraction and assay of monoterpene cyclase activity from conifer stem (wood and bark) tissue. The level of monoterpene cyclase activity for a given conifer species was shown to correlate closely with the monoterpene content of the oleoresin and with the degree of anatomical complexity of the specialized resin-secreting structures. Cyclase activity and monoterpene content were lowest in the stems of species containing only isolated resin cells, such as western red cedar (Thuja plicata D. Don). Increasing levels of cyclase activity and oleoresin monoterpenes were observed in advancing from species with multicellular resin blisters (true firs [Abies]) to those with organized resin passages, such as western larch (Larix occidentalis Nutt.), Colorado blue spruce (Picea pungens Engelm.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The highest levels of cyclase activity and oleoresin monoterpenes were noted in Pinus species that contain the most highly developed resin duct systems. The relationship between biosynthetic capacity, as measured by cyclase activity, monoterpene content, and the degree of organization of the secretory structures for a given species, may reflect the total number of specialized resin-producing cells per unit mass of stem tissue. PMID:16668182

  9. Amphibian macrophage development and antiviral defenses.

    PubMed

    Grayfer, Leon; Robert, Jacques

    2016-05-01

    Macrophage lineage cells represent the cornerstone of vertebrate physiology and immune defenses. In turn, comparative studies using non-mammalian animal models have revealed that evolutionarily distinct species have adopted diverse molecular and physiological strategies for controlling macrophage development and functions. Notably, amphibian species present a rich array of physiological and environmental adaptations, not to mention the peculiarity of metamorphosis from larval to adult stages of development, involving drastic transformation and differentiation of multiple new tissues. Thus it is not surprising that different amphibian species and their respective tadpole and adult stages have adopted unique hematopoietic strategies. Accordingly and in order to establish a more comprehensive view of these processes, here we review the hematopoietic and monopoietic strategies observed across amphibians, describe the present understanding of the molecular mechanisms driving amphibian, an in particular Xenopus laevis macrophage development and functional polarization, and discuss the roles of macrophage-lineage cells during ranavirus infections.

  10. Use of Ultrasound to Monitor Biceps Femoris Mechanical Adaptations after Injury in a Professional Soccer Player

    PubMed Central

    Kellis, Eleftherios; Galanis, Nikiforos; Chrysanthou, Chrysanthos; Kofotolis, Nikolaos

    2016-01-01

    This study examined the use of ultrasound to monitor changes in the long head of the biceps femoris (BF) architecture of aprofessional soccer player with acute first-time hamstring strain. The player followed a 14 session physiotherapy treatment until return to sport. The pennation angle and aponeurosis strain of the long head of the biceps femoris (BF) were monitored at 6 occasions (up until 1 year) after injury. The size of the scar / hematoma was reduced by 63.56% (length) and 67.9% (width) after the intervention and it was almost non-traceable one year after injury. The pennation angle of the fascicles underneath the scar showed a decline of 51.4% at the end of the intervention while an increase of 109.2% of the fascicles which were closer to deep aponeurosis was observed. In contrast, pennation angle of fascicles located away from the injury site were relatively unaffected. The treatment intervention resulted in a 57.9% to 77.3% decline of maximum strain per unit of MVC moment and remained similar one year after the intervention. This study provided an example of the potential use of ultrasound-based parameters to link the mechanical adaptations of the injured muscle to specific therapeutic intervention. Key points Changes in fascicle orientation after biceps femoris mild tear were reduced after a 28 day intervention and remained similar one year after injury. Tendon/aponeurosis strain per unit of moment of force decreased during the course of the therapeutic intervention. Future studies could utilize ultrasonography to monitor mechanical responses after various types of hamstring injury and interventions in order to improve criteria for a safe return to sport. PMID:26957929

  11. Early-Life Stress, HPA Axis Adaptation, and Mechanisms Contributing to Later Health Outcomes

    PubMed Central

    Maniam, Jayanthi; Antoniadis, Christopher; Morris, Margaret J.

    2014-01-01

    Stress activates the hypothalamic–pituitary–adrenal (HPA) axis, which then modulates the degree of adaptation and response to a later stressor. It is known that early-life stress can impact on later health but less is known about how early-life stress impairs HPA axis activity, contributing to maladaptation of the stress–response system. Early-life stress exposure (either prenatally or in the early postnatal period) can impact developmental pathways resulting in lasting structural and regulatory changes that predispose to adulthood disease. Epidemiological, clinical, and experimental studies have demonstrated that early-life stress produces long term hyper-responsiveness to stress with exaggerated circulating glucocorticoids, and enhanced anxiety and depression-like behaviors. Recently, evidence has emerged on early-life stress-induced metabolic derangements, for example hyperinsulinemia and altered insulin sensitivity on exposure to a high energy diet later in life. This draws our attention to the contribution of later environment to disease vulnerability. Early-life stress can alter the expression of genes in peripheral tissues, such as the glucocorticoid receptor and 11-beta hydroxysteroid dehydrogenase (11β-HSD1). We propose that interactions between altered HPA axis activity and liver 11β-HSD1 modulates both tissue and circulating glucocorticoid availability, with adverse metabolic consequences. This review discusses the potential mechanisms underlying early-life stress-induced maladaptation of the HPA axis, and its subsequent effects on energy utilization and expenditure. The effects of positive later environments as a means of ameliorating early-life stress-induced health deficits, and proposed mechanisms underpinning the interaction between early-life stress and subsequent detrimental environmental exposures on metabolic risk will be outlined. Limitations in current methodology linking early-life stress and later health outcomes will also be

  12. Use of Ultrasound to Monitor Biceps Femoris Mechanical Adaptations after Injury in a Professional Soccer Player.

    PubMed

    Kellis, Eleftherios; Galanis, Nikiforos; Chrysanthou, Chrysanthos; Kofotolis, Nikolaos

    2016-03-01

    This study examined the use of ultrasound to monitor changes in the long head of the biceps femoris (BF) architecture of aprofessional soccer player with acute first-time hamstring strain. The player followed a 14 session physiotherapy treatment until return to sport. The pennation angle and aponeurosis strain of the long head of the biceps femoris (BF) were monitored at 6 occasions (up until 1 year) after injury. The size of the scar / hematoma was reduced by 63.56% (length) and 67.9% (width) after the intervention and it was almost non-traceable one year after injury. The pennation angle of the fascicles underneath the scar showed a decline of 51.4% at the end of the intervention while an increase of 109.2% of the fascicles which were closer to deep aponeurosis was observed. In contrast, pennation angle of fascicles located away from the injury site were relatively unaffected. The treatment intervention resulted in a 57.9% to 77.3% decline of maximum strain per unit of MVC moment and remained similar one year after the intervention. This study provided an example of the potential use of ultrasound-based parameters to link the mechanical adaptations of the injured muscle to specific therapeutic intervention. Key pointsChanges in fascicle orientation after biceps femoris mild tear were reduced after a 28 day intervention and remained similar one year after injury.Tendon/aponeurosis strain per unit of moment of force decreased during the course of the therapeutic intervention.Future studies could utilize ultrasonography to monitor mechanical responses after various types of hamstring injury and interventions in order to improve criteria for a safe return to sport. PMID:26957929

  13. Oxygen sensing by the carotid body: mechanisms and role in adaptation to hypoxia.

    PubMed

    López-Barneo, José; González-Rodríguez, Patricia; Gao, Lin; Fernández-Agüera, M Carmen; Pardal, Ricardo; Ortega-Sáenz, Patricia

    2016-04-15

    Oxygen (O2) is fundamental for cell and whole-body homeostasis. Our understanding of the adaptive processes that take place in response to a lack of O2(hypoxia) has progressed significantly in recent years. The carotid body (CB) is the main arterial chemoreceptor that mediates the acute cardiorespiratory reflexes (hyperventilation and sympathetic activation) triggered by hypoxia. The CB is composed of clusters of cells (glomeruli) in close contact with blood vessels and nerve fibers. Glomus cells, the O2-sensitive elements in the CB, are neuron-like cells that contain O2-sensitive K(+)channels, which are inhibited by hypoxia. This leads to cell depolarization, Ca(2+)entry, and the release of transmitters to activate sensory fibers terminating at the respiratory center. The mechanism whereby O2modulates K(+)channels has remained elusive, although several appealing hypotheses have been postulated. Recent data suggest that mitochondria complex I signaling to membrane K(+)channels plays a fundamental role in acute O2sensing. CB activation during exposure to low Po2is also necessary for acclimatization to chronic hypoxia. CB growth during sustained hypoxia depends on the activation of a resident population of stem cells, which are also activated by transmitters released from the O2-sensitive glomus cells. These advances should foster further studies on the role of CB dysfunction in the pathogenesis of highly prevalent human diseases.

  14. Adaptive Physiological Response to Perceived Scarcity as a Mechanism of Sensory Modulation of Life Span

    PubMed Central

    Waterson, Michael J.; Chan, Tammy P.

    2015-01-01

    Chemosensation is a potent modulator of organismal physiology and longevity. In Drosophila, loss of recognition of diverse tastants has significant and bidirectional life-span effects. Recently published results revealed that when flies were unable to taste water, they increased its internal generation, which may have subsequently altered life span. To determine whether similar adaptive responses occur in other contexts, we explored the impact of sensory deficiency of other metabolically important molecules. Trehalose is a major circulating carbohydrate in the fly that is recognized by the gustatory receptor Gr5a. Gr5a mutant flies are short lived, and we found that they specifically increased whole-body and circulating levels of trehalose, but not other carbohydrates, likely through upregulation of de novo synthesis. dILP2 transcript levels were increased in Gr5a mutants, a possible response intended to reduce hypertrehalosemia, and likely a contributing factor to their reduced life span. Together, these data suggest that compensatory physiological responses to perceived environmental scarcity, which are designed to alleviate the ostensive shortage, may be a common outcome of sensory manipulation. We suggest that future investigations into the mechanisms underlying sensory modulation of aging may benefit by focusing on direct or indirect consequences of physiological changes that are designed to correct perceived disparity with the environment. PMID:25878032

  15. NaCl-induced physiological and biochemical adaptative mechanisms in the ornamental Myrtus communis L. plants.

    PubMed

    Acosta-Motos, José Ramón; Diaz-Vivancos, Pedro; Álvarez, Sara; Fernández-García, Nieves; Sánchez-Blanco, María Jesús; Hernández, José Antonio

    2015-07-01

    Physiological and biochemical changes in Myrtus communis L. plants after being subjected to different solutions of NaCl (44, and 88 mM) for up to 30 days (Phase I) and after recovery from the salinity period (Phase II) were studied. Myrtle plants showed salinity tolerance by displaying a series of adaptative mechanisms to cope with salt-stress, including controlled ion homeostasis, the increase in root/shoot ratio, the reduction of water potentials and stomatal conductance to limit water loss. In addition, they displayed different strategies to protect the photosynthetic machinery, including limiting toxic ion accumulation in leaves, increase in chlorophyll content, and changes in chlorophyll fluorescence parameters, leaf anatomy and increases in catalase activity. Anatomical modifications in leaves, including a decrease in spongy parenchyma and increased intercellular spaces, allow CO2 diffusion in a situation of reduced stomatal aperture. In spite of all these changes, salinity produced oxidative stress in myrtle plants as monitored by increases in oxidative stress parameter values. The post-recovery period is perceived as a new stress situation, as observed through effects on plant growth and alterations in non-photochemical quenching parameters and lipid peroxidation values.

  16. Toward a mechanics of adaptive behavior: evolutionary dynamics and matching theory statics.

    PubMed

    McDowell, J J; Popa, Andrei

    2010-09-01

    One theory of behavior dynamics instantiates the idea that behavior evolves in response to selection pressure from the environment in the form of reinforcement. This computational theory implements Darwinian principles of selection, reproduction, and mutation, which operate on a population of potential behaviors by means of a genetic algorithm. The behavior of virtual organisms animated by this theory may be studied in any experimental environment. The evolutionary theory was tested by comparing the steady-state behavior it generated on concurrent schedules to the description of steady state behavior provided by modern matching theory. Ensemble fits of modern matching theory that enforced its constant-k requirement and the parametric identities required by its equations, accounted for large proportions of data variance, left random residuals, and yielded parameter estimates with values and properties similar to those obtained in experiments with live organisms. These results indicate that the dynamics of the evolutionary theory and the statics of modern matching theory together constitute a good candidate for a mechanics of adaptive behavior.

  17. Toward a Mechanics of Adaptive Behavior: Evolutionary Dynamics and Matching Theory Statics

    PubMed Central

    McDowell, J.J; Popa, Andrei

    2010-01-01

    One theory of behavior dynamics instantiates the idea that behavior evolves in response to selection pressure from the environment in the form of reinforcement. This computational theory implements Darwinian principles of selection, reproduction, and mutation, which operate on a population of potential behaviors by means of a genetic algorithm. The behavior of virtual organisms animated by this theory may be studied in any experimental environment. The evolutionary theory was tested by comparing the steady-state behavior it generated on concurrent schedules to the description of steady state behavior provided by modern matching theory. Ensemble fits of modern matching theory that enforced its constant-k requirement and the parametric identities required by its equations, accounted for large proportions of data variance, left random residuals, and yielded parameter estimates with values and properties similar to those obtained in experiments with live organisms. These results indicate that the dynamics of the evolut