Now showing 1 - 10 of 10
  • Publication
    Methods to study plant programmed cell death
    Programmed cell death (PCD) is a critical component of plant development, defense against invading pathogens, and response to environmental stresses. In this chapter, we provide detailed technical methods for studying PCD associated with plant development or induced by abiotic stress. A root hair assay or electrolyte leakage assay are excellent techniques for the quantitative determination of PCD and/or cellular injury induced in response to abiotic stress, whereas the lace plant provides a unique model that facilitates the study of genetically regulated PCD during leaf development.
      326Scopus© Citations 12
  • Publication
    Wing membrane biopsies for bat cytogenetics: Finding of 2n = 54 in irish Rhinolophus hipposideros (rhinolophidae, chiroptera, mammalia) supports two geographically separated chromosomal variants in Europe
    In Europe, 2 different diploid chromosome numbers, 2n = 54 and 2n = 56, have been described in the lesser horseshoe bat (Rhinolophushipposideros). The eastern form with 2n = 56 extends from the Czech Republic to Greece. To date, specimens with 54 chromosomes have been reported only from Spain and Germany. This study expands the distributional area of the western variant to Ireland. Strikingly, this distribution of European chromosomal variants is in contrast to the available molecular data that indicate little genetic differentiation of R. hipposideros populations spanning Northwestern to Central Europe. Further, we have developed an optimized protocol for establishing fibroblast cell cultures, suitable for karyotype analyses, from 3-mm wing membrane biopsies. This is a useful technique for cytogenetic studies of endangered bat species, as this non-lethal sampling method imposes only minimum stress to the animal without lasting adverse effects and is routinely used to sample tissue probes for molecular genetic studies in bats.
    Scopus© Citations 7  166
  • Publication
    The Fusarium Mycotoxin Deoxynivalenol Can Inhibit Plant Apoptosis-Like Programmed Cell Death
    The Fusarium genus of fungi is responsible for commercially devastating crop diseases and the contamination of cereals with harmful mycotoxins. Fusarium mycotoxins aid infection, establishment, and spread of the fungus within the host plant. We investigated the effects of the Fusarium mycotoxin deoxynivalenol (DON) on the viability of Arabidopsis cells. Although it is known to trigger apoptosis in animal cells, DON treatment at low concentrations surprisingly did not kill these cells. On the contrary, we found that DON inhibited apoptosis-like programmed cell death (PCD) in Arabidopsis cells subjected to abiotic stress treatment in a manner independent of mitochondrial cytochrome c release. This suggested that Fusarium may utilise mycotoxins to suppress plant apoptosis-like PCD. To test this, we infected Arabidopsis cells with a wild type and a DON-minus mutant strain of F. graminearum and found that only the DON producing strain could inhibit death induced by heat treatment. These results indicate that mycotoxins may be capable of disarming plant apoptosis-like PCD and thereby suggest a novel way that some fungi can influence plant cell fate.                         
      360Scopus© Citations 52
  • Publication
    The botanical dance of death : programmed cell death in plants
    (Academic Press (Elsevier), 2011-10) ; ;
    Programmed cell death (PCD) describes a small number of processes that result in a highly controlled, and organised, form of cellular destruction, activated in every part of the plant, throughout its entire life cycle. For example, PCD is a critical component of many vegetative and reproductive developmental processes, senescence programmes, pathogen defence mechanisms and stress responses. Cell destruction can manifest as apoptotic-like, necrotic or autophagic cell death and these processes are likely to overlap extensively, sharing several regulatory mechanisms. Several of the key PCD regulators and signals have now been revealed, for example, many cell organelles, including mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum and vacuoles have been shown to have a role in controlling PCD activation. Following activation the actual dismantling of the cell appears to involve cell death proteases including those with caspase-like, or metacaspase, activity. This review will examine the current state of knowledge about the regulation of events during plant PCD. We will describe numerous examples of developmental or environmentally-induced deaths and outline their potential as models systems for use in PCD research programmes. Similarly, a range of techniques and in vitro model systems and that can be used to identify, and quantify, rates of plant PCD are reviewed. These model systems and techniques can be used to identify the underlying signals and events that drive and regulate PCD and ultimately reveal the steps necessary for the botanical dance of death.
      2578Scopus© Citations 63
  • Publication
    Examining gender effects in different types of undergraduate science assessment
    The optimum assessment structure measures student knowledge accurately and without bias. In this study, the performance of the first-year undergraduate science students from the University College Dublin was evaluated to test the gender equality of the assessment structure in place. Results of male and female students taking three life science modules were analysed, for two academic years, with assessment structure based on a combination of three types of evaluation: continuous assessment and multiple choice questions (MCQ) exam scored with/without negative marking. We found no significant gender effect associated with performance in continuous assessment, or MCQ exams scored without negative marking. However, a significant bias against females was consistently observed for the same cohort of students in the MCQ exams with negative marking of 0.25 points. This bias was at least partially linked to a gender difference in willingness to guess and preliminary data suggest that it disappears after removal of negative marking from the MCQ exams. Our results support the view of a diverse assessment structure being fairer to the students. Moreover, caution is advised while using negative marking, and regular reviews of assessment strategy should be implemented by higher education institutions to ensure gender-bias free evaluation of students’ performance.
      250Scopus© Citations 5
  • Publication
    Light influences how the fungal toxin deoxynivalenol affects plant cell death and defense responses
    The Fusarium mycotoxin deoxynivalenol (DON) can cause cell death in wheat (Triticum aestivum), but can also reduce the level of cell death caused by heat shock in Arabidopsis (Arabidopsis thaliana) cell cultures. We show that 10 μg mL−1 DON does not cause cell death in Arabidopsis cell cultures, and its ability to retard heat-induced cell death is light dependent. Under dark conditions, it actually promoted heat-induced cell death. Wheat cultivars differ in their ability to resist this toxin, and we investigated if the ability of wheat to mount defense responses was light dependent. We found no evidence that light affected the transcription of defense genes in DON-treated roots of seedlings of two wheat cultivars, namely cultivar CM82036 that is resistant to DON-induced bleaching of spikelet tissue and cultivar Remus that is not. However, DON treatment of roots led to genotype-dependent and light-enhanced defense transcript accumulation in coleoptiles. Wheat transcripts encoding a phenylalanine ammonia lyase (PAL) gene (previously associated with Fusarium resistance), non-expressor of pathogenesis-related genes-1 (NPR1) and a class III plant peroxidase (POX) were DON-upregulated in coleoptiles of wheat cultivar CM82036 but not of cultivar Remus, and DON-upregulation of these transcripts in cultivar CM82036 was light enhanced. Light and genotype-dependent differences in the DON/DON derivative content of coleoptiles were also observed. These results, coupled with previous findings regarding the effect of DON on plants, show that light either directly or indirectly influences the plant defense responses to DON.
      417Scopus© Citations 12
  • Publication
    The retraction of the protoplast during PCD is an active, and interruptible, calcium-flux driven process
    The protoplast retracts during apoptosis-like programmed cell death (AL-PCD) and, if this retraction is an active component of AL-PCD, it should be used as a defining feature for this type of programmed cell death. We used an array of pharmacological and genetic tools to test if the rates of protoplast retraction in cells undergoing AL-PCD can be modulated. Disturbing calcium flux signalling, ATP synthesis and mitochondrial permeability transition all inhibited protoplast retraction and often also the execution of the death programme. Protoplast retraction can precede loss of plasma membrane integrity and cell death can be interrupted after the protoplast retraction had already occurred. Blocking calcium influx inhibited the protoplast retraction, reduced DNA fragmentation and delayed death induced by AL-PCD associated stresses. At higher levels of stress, where cell death occurs without protoplast retraction, blocking calcium flux had no effect on the death process. The results therefore strongly suggest that retraction of the protoplast is an active biological process dependent on an early Ca2+-mediated trigger rather than cellular disintegration due to plasma membrane damage. Therefore this morphologically distinct cell type is a quantifiable feature, and consequently, reporter of AL-PCD.
    Scopus© Citations 15  230
  • Publication
    A potent anti-inflammatory response in bat macrophages may be linked to extended longevity and viral tolerance
    Bats are unique among mammals given their ability to fly, apparent tolerance of deadly viruses and extraordinary longevity. We propose that these traits are linked and driven by adaptations of the innate immune system. To explore this hypothesis we challenged macrophages from the greater mouse-eared bat, Myotis myotis and the house mouse, Mus musculus with Toll Like Receptors (TLRs) ligands, lipopolysaccharides, LPS and polyinosinic-polycytidylic acid, Poly(I:C). Macrophages from both species presented a high level of mRNA induction of inferon ß ( INF-ß) , tumor necrosis factor ( TNF) and interleukin-1ß (Il- ß) . However, in bat macrophages, this antiviral, proinflammatory response was balanced by a sustained high-level transcription of the anti-inflammatory cytokine Il-10, which was not observed in mouse, potentially resulting from adaptive regulation in bats. Additionally, phylogenomic selection tests across the basal divergences in mammals (n = 39) uncovered bat-specific adaptations in six genes involved in antiviral and proinflammatory signalling. Based on this pilot study, we put forward a hypothesis that bats may have evolved unique anti-inflamma tory responses to neutralize proinflammatory stimuli resulting from flight. This in turn may drive their extraordinary longevity and viral tolerance by limiting inflammation driven ageing and infection-induced immunopathology. Further data from other individuals and bat species are required to advance this intriguing hypothesis.
      1116Scopus© Citations 43
  • Publication
    A root hair assay to expedite cell death research
    (Humana Press and Springer, 2015-01-01) ;
    Programmed cell death can be defined as an organized cellular destruction and can be activated throughout plant development, as a defense response against invading pathogens or during environmental stress. The root hair assay presented herein enables in vivo quantitative measurements of programmed cell death based on the morphological changes of dying root hairs. Application of this novel, simple technique eliminates the need for establishing cell suspension cultures, resulting in a significant reduction in time, cost, and labor input. Here, we present a detailed root hair assay protocol for the dicotyledonous model plant Arabidopsis thaliana, where results from germination to scoring of cell death can be obtained within 7 days. We also suggest and present a panel of cell death inducing treatments which can be used to study abiotic stress- and mycotoxin-induced programmed cell death in the root hair system in Arabidopsis. A root hair assay protocol for the monocotyledonous model species Brachypodium distachyon is also included.
      308Scopus© Citations 4
  • Publication
    An in vivo root hair assay for determining rates of apoptotic-like programmed cell death in plants
    In Arabidopsis thaliana we demonstrate that dying root hairs provide an easy and rapid in vivo model for the morphological identification of apoptotic-like programmed cell death in plants. The model described here is transferable between the species, can be used to investigate the rates of AL-PCD in response to various treatments and to identify modulation of AL-PCD rates in mutant/transgenic plant lines facilitating rapid screening of mutant populations in order to identify genes involved in AL-PCD regulation
      519Scopus© Citations 32