225 research outputs found

    Oxygen deprivation stress in a changing environment

    Get PDF
    Past research into flooding tolerance and oxygen shortages in plants has been motivated largely by cultivation problems of arable crops. Unfortunately, such species are unsuitable for investigating the physiological and biochemical basis of anoxia-tolerance as selection has reduced any tolerance of anaerobiosis and anaerobic soil conditions that their wild ancestors might have possessed. Restoration of anoxia-tolerance to species that have lost this property is served better by physiological and molecular studies of the mechanisms that are employed in wild species that still possess long-term anoxia-tolerance. Case studies developing these arguments are presented in relation to a selection of crop and wild species. The flooding sensitivity and metabolism of maize is compared in relation to rice in its capacity for anaerobic germination. The sensitivity of potato to flooding is related to its disturbed energy metabolism and inability to maintain functioning membranes under anoxia and postinoxia. By contrast, long-term anoxia-tolerance in the American cranberry (Vaccinium macrocarpon) and the arctic grass species Deschampsia beringensis can be related to the provision and utilization of carbohydrate reserves. Among temperate species, the sweet flag (Acorus calamus) shows a remarkable tolerance of anoxia in both shoots and roots and is also able to mobilize carbohydrate and maintain ATP levels during anoxia as well as preserving membrane lipids against anoxic and post-anoxic injury. Phragmites australis and Spartina alterniflora, although anoxia-tolerant, are both sulphide-sensitive species which can pre-dispose them to the phenomenon of die-back in stagnant, nutrient-rich water. Glyceria maxima adapts to flooding through phenological adaptations with a seasonal metabolic tolerance of anoxia confined to winter and spring which, combined with a facility for root aeration and early spring growth, allows rapid colonization of sites with only shallow flooding. The diversity of responses to flooding in wild plants suggests that, depending on the life strategy and habitat of the species, many different mechanisms may be involved in adapting plants to survive periods of inundation and no one mechanism on its own is adequate for ensuring surviva

    Catalase Activity and Post-anoxic Injury in Monocotyledonous Species

    Get PDF
    Three anoxia-intolerant species, Glyceria maxima, Juncus effusus and Iris germanica (var. Quechei), and three anoxia-tolerant species Schoenoplectus lacustris, Acorus calamus and Iris pseudacorus were chosen for investigation. Rhizomes of anoxia-intolerant species show increased catalase activities when returned to air after periods of prolonged anoxia. Levels of catalase remained fairly constant in anoxia-tolerant species under the same conditions. In the anoxia intolerant G. maxima, the post-anoxic increase in catalase activity was reduced by circulating the anaerobic atmosphere. This treatment also reduced the ethanol content of the tissue under incubation, and increased the survival of the rhizomes as seen in their ability to resume growth in the post-anoxic phase. Exposure of anaerobic G. maxima rhizomes to ethanol vapour increased post-anoxic levels of catalase activity and when this produced a 5-fold increase always resulted in death of the rhizomes. Acetaldehyde vapour applied in the same way gave rise to increases in catalase activity followed by rapid death of the rhizomes. It is suggested that post-anoxic oxidation of anaerobically accumulated ethanol may result in a surge of acetaldehyde production, which could exert a toxic effect on the recovering tissues. The possible role of catalase in an ethanol-oxidation reaction, which is well documented in animals, is discussed in the light of the association between the natural accumulation of large concentrations of ethanol and subsequent post-anoxic death in some plant tissue

    Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being

    Get PDF
    This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics

    Shareholder protection, income inequality and social health:a proposed research agenda

    Get PDF
    This paper develops a proposed research agenda in order to highlight how corporate governance, accounting and company law are relevant to the consideration of income inequality and wider social health. To illustrate this proposed research agenda, this paper draws on corporate governance research in the law and finance tradition, as well as macro-level studies in accounting concerned with the wider corporate governance context, in order to consider the association between shareholder protection, income inequality and child mortality. Under 5 child mortality is an objective indication of a country’s ability to nurture its children. In an influential body of work, La Porta et al. (1997a, 1997b, 1998, 2008) concluded that a common law legal system which protected the interests of shareholders gave rise to better economic and social outcomes. However, drawing on corporate governance and accounting literature we contend that such a conclusion is flawed. The findings of this paper suggest that common law countries (i.e. those with the greater legal protection for investors) have worse social outcomes in terms of under-5 child mortality.PostprintPeer reviewe

    Networked buffering: a basic mechanism for distributed robustness in complex adaptive systems

    Get PDF
    A generic mechanism - networked buffering - is proposed for the generation of robust traits in complex systems. It requires two basic conditions to be satisfied: 1) agents are versatile enough to perform more than one single functional role within a system and 2) agents are degenerate, i.e. there exists partial overlap in the functional capabilities of agents. Given these prerequisites, degenerate systems can readily produce a distributed systemic response to local perturbations. Reciprocally, excess resources related to a single function can indirectly support multiple unrelated functions within a degenerate system. In models of genome:proteome mappings for which localized decision-making and modularity of genetic functions are assumed, we verify that such distributed compensatory effects cause enhanced robustness of system traits. The conditions needed for networked buffering to occur are neither demanding nor rare, supporting the conjecture that degeneracy may fundamentally underpin distributed robustness within several biotic and abiotic systems. For instance, networked buffering offers new insights into systems engineering and planning activities that occur under high uncertainty. It may also help explain recent developments in understanding the origins of resilience within complex ecosystems. \ud \u

    Evaluation des activités d’information et de sensibilisation du Programme Cantonal Tabac Tessinois (PCT1) : rapport final

    Get PDF
    Le programme cantonal tabac 2015-2018 du canton du Tessin a pour but de consolider la dénormalisation de la consommation de tabac au sein de la population tessinoise. Parmi les projets qui composent ce programme, le PCT1 a pour objectif principal de produire et de diffuser différents supports d’information et d’assurer une présence sur le terrain afin de sensibiliser la population aux risques liés à la consommation de tabac. Objectifs de la phase finale de l’évaluation: La phase finale de cette évaluation poursuivait les trois objectifs principaux suivants : 1) mesurer l’atteinte des objectifs du PCT1 en matière de couverture, de diffusion de connaissances et d’impact sur les attitudes en lien avec le tabagisme et sa prévention au sein de la population tessinoise ; 2) identifier les pratiques exemplaires en matière de communication à large échelle de message de prévention du tabagisme ; 3) mieux comprendre les processus à l’oeuvre dans le pilotage et la mise en oeuvre du PCT1

    Bias and Evolution of the Mutationally Accessible Phenotypic Space in a Developmental System

    Get PDF
    Genetic and developmental architecture may bias the mutationally available phenotypic spectrum. Although such asymmetries in the introduction of variation may influence possible evolutionary trajectories, we lack quantitative characterization of biases in mutationally inducible phenotypic variation, their genotype-dependence, and their underlying molecular and developmental causes. Here we quantify the mutationally accessible phenotypic spectrum of the vulval developmental system using mutation accumulation (MA) lines derived from four wild isolates of the nematodes Caenorhabditis elegans and C. briggsae. The results confirm that on average, spontaneous mutations degrade developmental precision, with MA lines showing a low, yet consistently increased, proportion of developmental defects and variants. This result indicates strong purifying selection acting to maintain an invariant vulval phenotype. Both developmental system and genotype significantly bias the spectrum of mutationally inducible phenotypic variants. First, irrespective of genotype, there is a developmental bias, such that certain phenotypic variants are commonly induced by MA, while others are very rarely or never induced. Second, we found that both the degree and spectrum of mutationally accessible phenotypic variation are genotype-dependent. Overall, C. briggsae MA lines exhibited a two-fold higher decline in precision than the C. elegans MA lines. Moreover, the propensity to generate specific developmental variants depended on the genetic background. We show that such genotype-specific developmental biases are likely due to cryptic quantitative variation in activities of underlying molecular cascades. This analysis allowed us to identify the mutationally most sensitive elements of the vulval developmental system, which may indicate axes of potential evolutionary variation. Consistent with this scenario, we found that evolutionary trends in the vulval system concern the phenotypic characters that are most easily affected by mutation. This study provides an empirical assessment of developmental bias and the evolution of mutationally accessible phenotypes and supports the notion that such bias may influence the directions of evolutionary change

    Real-Time Analysis of Alarm Pheromone Emission by the Pea Aphid (Acyrthosiphon Pisum) Under Predation

    Get PDF
    Upon attack by predators or parasitoids, aphids emit volatile chemical alarm signals that warn other aphids of a potential risk of predation. Release rate of the major constituent of the alarm pheromone in pea aphids (Acyrthosiphon pisum), (E)-ß-farnesene (EBF), was measured for all nymphal and the adult stage as aphids were attacked individually by lacewing (Chrysoperla carnae) larvae. Volatilization of EBF from aphids under attack was quantified continuously for 60 min at 2-min intervals with a rapid gas chromatography technique (zNose™) to monitor headspace emissions. After an initial burst, EBF volatilization declined exponentially, and detectable amounts were still present after 30 min in most cases. Total emission of EBF averaged 16.33 ± 1.54 ng and ranged from 1.18 to 48.85 ng. Emission was higher in nymphs as compared to adults. No differences between pea aphid life stages were detected for their speed of alarm signal emission in response to lacewing larvae attack. This is the first time that alarm pheromone emission from single aphids has been reported

    Obecabtagene Autoleucel in Adults with B-Cell Acute Lymphoblastic Leukemia

    Get PDF
    BACKGROUND: Obecabtagene autoleucel (obe-cel) is an autologous 41BB-ζ anti-CD19 chimeric antigen receptor (CAR) T-cell therapy which uses an intermediate-affinity CAR to reduce toxic effects and improve persistence. METHODS: We conducted a phase 1b-2 multicenter study of obe-cel in adults (≥18 years of age) with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). The main cohort, cohort 2A, included patients with morphologic disease; patients in cohort 2B had measurable residual disease. The primary end point was overall remission (complete remission or complete remission with incomplete hematologic recovery) in cohort 2A. Secondary end points included event-free survival, overall survival, and safety. RESULTS: Of the 153 enrolled patients, 127 (83.0%) received at least one infusion of obe-cel and were evaluable. In cohort 2A (94 patients; median follow-up, 20.3 months), overall remission occurred in 77% (95% confidence interval [CI], 67 to 85), with complete remission in 55% (95% CI, 45 to 66) and complete remission with incomplete hematologic recovery in 21% (95% CI, 14 to 31). The prespecified null hypotheses of overall remission (≤40%) and complete remission (≤20%) were rejected (P<0.001). In the 127 patients who received at least one obe-cel infusion (median follow-up, 21.5 months), the median event-free survival was 11.9 months (95% CI, 8.0 to 22.1); estimated 6- and 12-month event-free survival was 65.4% and 49.5%, respectively. The median overall survival was 15.6 months (95% CI, 12.9 to not evaluable); estimated 6- and 12-month overall survival was 80.3% and 61.1%, respectively. Grade 3 or higher cytokine release syndrome developed in 2.4% of the patients, and grade 3 or higher immune effector cell-associated neurotoxicity syndrome developed in 7.1% of the patients. CONCLUSIONS: Obe-cel resulted in a high incidence of durable response among adults with relapsed or refractory B-cell ALL, with a low incidence of grade 3 or higher immune-related toxic effects. (Funded by Autolus Therapeutics); FELIX ClinicalTrials.gov number, NCT04404660.)
    corecore