394 research outputs found
Green light for lipid fingerprinting
No full textThe use of targeted lipidomic approaches for the analysis of plant lipids has steadily increased during recent years. We review recent developments of these methods and suggest the introduction of discovery lipidomics as additional approach through a new workflow, lipid fingerprinting, that integrates the advantages of shotgun lipidomics (quantitative data) with LC-MS-based strategies (higher resolution and/or coverage). This article is part of a Special Issue entitled:BBALIP_Lipidomics Opinion Articles edited by Sepp Kohlwein
Social Support
No full textFirst paragraph: Flick through any autobiography of a celebrated athlete and you will find that one of its key themes is social support. Certainly there will be discussions of training and tactics, distress and disappointment, guts and glory. But the backdrop to all this is likely to be the support the athlete received from key individuals and groups along the way. The mother who drove them to training every day in the middle of winter, the coach who instilled a sense of self-discipline and pride, the backroom team who always had a kind word when things hadn’t gone quite to plan. This is beautifully exemplified by a legendary yet bitter-sweet moment from the 1992 Barcelona Olympics, where hot-favourite sprinter Derek Redmond from the United Kingdom tore his hamstring during the 400 meters semi-final. His father, Jim, jumped the balustrades and pushed past event officials to help his son cross the line and finish the race. We hobbled over the finishing line with our arms round each other, just me and my dad, the man I’m really close to, who’s supported my athletics career since I was seven years old. (Bos, 2017) Accounts such as this are also often filled with heroic examples of athletes going ‘above and beyond’ to provide support to others in their team — even to the extent of making personal sacrifices for the ‘greater good’. Consider the 2012 Tour de France, when Chris Froome gave up his opportunity to secure personal victory, instead opting to help his teammate Bradley Wiggins secure the coveted maillot jaune. Clearly, the role of socially supportive others, across both sport and life more generally, cannot be understated. For this reason, social support plays a key role in optimal functioning across a range of performance contexts — not only in sport, but also in the workplace, at school, or at home (Fletcher & Sarkar, 2012; Freeman & Rees, 2009; Sarkar & Fletcher, 2014). Indeed, work by the fourth author and his colleagues highlighted how supportive families, coaches, and networks are key to the development of super-elite athletes (Rees et al., 2016)
Having a lot of a good thing: multiple important group memberships as a source of self-esteem.
No full textCopyright: © 2015 Jetten et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedMembership in important social groups can promote a positive identity. We propose and test an identity resource model in which personal self-esteem is boosted by membership in additional important social groups. Belonging to multiple important group memberships predicts personal self-esteem in children (Study 1a), older adults (Study 1b), and former residents of a homeless shelter (Study 1c). Study 2 shows that the effects of multiple important group memberships on personal self-esteem are not reducible to number of interpersonal ties. Studies 3a and 3b provide longitudinal evidence that multiple important group memberships predict personal self-esteem over time. Studies 4 and 5 show that collective self-esteem mediates this effect, suggesting that membership in multiple important groups boosts personal self-esteem because people take pride in, and derive meaning from, important group memberships. Discussion focuses on when and why important group memberships act as a social resource that fuels personal self-esteem.This study was supported by 1. Australian Research Council Future Fellowship (FT110100238) awarded to Jolanda Jetten (see http://www.arc.gov.au) 2. Australian Research Council Linkage Grant (LP110200437) to Jolanda Jetten and Genevieve Dingle (see http://www.arc.gov.au) 3. support from the Canadian Institute for Advanced Research Social Interactions, Identity and Well-Being Program to Nyla Branscombe, S. Alexander Haslam, and Catherine Haslam (see http://www.cifar.ca)
Heat stress resistance in Camelina sativa: effects on morphology, physiology, yield, and seed quality
No full textCultivated crops are increasingly exposed to episodes of extreme heat. In the
Mediterranean basin, crops often experience heat stress during spring or
summer, coinciding with flowering and seed ripening. Recently, Camelina
sativa has emerged as an alternative oilseed crop of interest due to its
resistance to abiotic stresses. To investigate possible mechanisms underlying
camelina’s ability to cope with heat stress and to evaluate the role of tocopherols,
two spring varieties (Cypress and Omega) were tested in two controlledenvironment
experiments. Heat was imposed for five consecutive days either
from the end of flowering (EXP1) or from the stage when siliques reached their
final size (EXP2). Early imposition of heat stress (EXP1) had the greatest impact on
camelina morphological parameters during the growth cycle. At harvest in EXP1,
only the genotype significantly affected plant height and seed yield, with Omega
producing taller plants and higher seed yield (0.83 g per plant) compared with
Cypress (0.70 g per plant). In EXP2, cultivar significantly affected only straw
weight, which was higher in Omega. Nonetheless, Cypress exhibited the highest
1,000-seed weight in both experiments (1.36 g in EXP1 and 1.34 g in EXP2). Seed
oil content was reduced by heat stress (− 9.89% in EXP1 and − 11.6% in EXP2,
respectively). Fatty acid composition in EXP1 was mainly influenced by the
cultivar, except for C18:1, whereas in EXP2, heat stress predominantly affected
18-carbon fatty acids. Total tocopherol content was largely under genetic
control, and although a-tocopherol is associated with responses to abiotic
stress, it increased only when stress was imposed at a later stage (+ 75.8% in
the stressed plants). Despite the high tocopherol content of camelina, it
appeared to contribute to plant stress resistance only under late-stage heat
stress during seed maturation
SLiMFinder: a web server to find novel, significantly over-represented, short protein motifs
No full textShort, linear motifs (SLiMs) play a critical role in many biological processes, particularly in protein–protein interactions. The SLiMFinder (Short, Linear Motif Finder) web server is a de novo motif discovery tool that identifies statistically over-represented motifs in a set of protein sequences, accounting for the evolutionary relationships between them. Motifs are returned with an intuitive p¬-value that greatly reduces the problem of False Positives and is accessible to biologists of all disciplines. Input can be uploaded by the user or extracted directly from UniProt. Numerous masking options give the user great control over the contextual information to be included in the analyses. The SLiMFinder server combines these with user-friendly output and visualisations of motif context to allow the user to quickly gain insight into the validity of a putatively functional motif. These visualisations include alignments of motif occurrences, alignments of motifs and their homologues and a visual schematic of the top-ranked motifs. Returned motifs can also be compared to known SLiMs from the literature using CompariMotif. All results are available for download. The SLiMFinder server is available at: http://bioware.ucd.ie/slimfinder.html
Targets of cyclic GMP in Blood Platelets: Photolabelling, mutagenesis and pharmacological analysis of the cyclic GMP-inhibited phosphodiesterase
No full textThe first objective of this thesis was to investigate the targets of cyclic GMP (cGMP) action in platelets. Proteins that bind cGMP were first detected by photoaffinity labelling with [³²P]cGMP and subsequently identified by molecular, pharmacological and immunological criteria. Since cGMP was already known to exert major effects in platelets through the cGMP-inhibited phosphodiesterase family (PDE3) (Maurice and Haslam, 1990a), an additional objective was to explore the molecular basis of the unique properties of this enzyme by cloning and mutagenesis studies. A photolabelling technique using [³²P]cGMP was modified to permit the rapid detection of cGMP-binding proteins in crude platelet extracts. Five labelled proteins (110, 80, 55, 49 and 38 kDa) were detected in platelet supernatant and four (80, 65, 49 and 38 kDa) in platelet membranes. The sensitivity of photolabelling to PDE3 inhibitors and specific immunoprecipitation established that the 110 kDa photolabelled species was a product of the PDE3 gene family. In addition, the 80 kDa species was identified as cGMP-dependent protein kinase (PKG) by similar methods. Interestingly, cyclic AMP (cAMP) greatly enhanced the labelling of the 80 kDa protein, suggesting the existence of a novel co-operative interaction between cAMP and cGMP. This study also detected a previously unknown 65 kDa cGMP-binding protein in platelet membranes. Since both cAMP and cGMP inhibited labelling of this protein, it may represent a novel target for both cyclic nucleotides in platelets, possibly a subunit of a cyclic nucleotide-gated (CNG) ion channel. The inhibitory effects of variouus compounds on the photolabelling of PDE3 were quantitated by [³²P]cGMP. Thus, concentration-dependent inhibition of photolabelling of PDE3 was observed with trequinsin (IC₅₀ = 13 ± 2 nM), lixazinone (IC₅₀ = 22 ± 4 nM), milrinone (IC₅₀ = 56 ± 12 nM), cilostamide (IC₅₀ = 70 ± 9 nM), siguazodan (IC₅₀ 117 ± 29 nM) and 3-isobutyl 1-methylxanthine (IBMX) (IC₅₀ = 3950 ± 22 nM). The effects of these phosphodiesterase inhibitors on iloproststimulated cAMP accumulation in intact platelets were also investigated. Discrepancies between the abilities of these compounds to inhibit photolabelling of PDE3 and to increase platelet cAMP accumulation are probably related to differences in the rates of entry of the individual inhibitors into the intact platelet. The general applicability of this photolabelling technique and its value in the detection of novel cGMP-binding proteins in crude cell extracts was demonstrated in rat tissues. Distinctive photolabelling patterns were observed in different rat tissues and the 110 kDa protein found in human platelets was replaced by a 115 kDa species in rat platelets. To clarify the molecular mechanisms by which cGMP and inhibitory drugs modulate PDE3 activity, an attempt was made to define the roles of different PDE3 domains in the action of the enzyme. To that end, the C-terminal half of platelet PDE3 was cloned, identified as a product of the PDE3A gene and expressed as an active enzyme in E.coli. Further deletion mutants were generated by removing either an additional 100 amino acids from the N-terminus or the 44 amino acid insert, characteristic of members of the PDE3 family, from the catalytic domain. Site-directed mutagenesis of the 44 amino acid insert was also conducted to explore the function of this region. Kinetic analysis of these mutant enzymes demonstrated that the deletion of N-terminal sequences from PDE3 was accompanied by progressively lower Km values and by an increased Vmax for cGMP relative to that for cAMP. Thus, N-terminal sequences exert modulatory effects on cGMP hydrolysis. Deletion of the 44 amino acid insert abolished enzyme activity, as did site-directed mutagenesis of putative β-turns located at the N- and C-termini of the insert. Mutation of a cluster of negatively charged residues in the insert did not have major effects on the hydrolysis of cAMP or cGMP. The results suggest that this insert is required to preserve an effective catalytic domain structure in PDE3. In conclusion, the major targets of cGMP in platelets were shown to include not only PKG, but also PDE3A and an unidentified membrane protein, possibly a CNG ion channel. This thesis has also identified some of the functionally and structurally important domains within PDE3A.Doctor of Philosophy (PhD
Lipidomic analysis of plasma from healthy men and women shows phospholipid class and molecular species differences between sexes
No full textThe phospholipid composition of lipoproteins is determined by the specificity of hepatic phospholipid biosynthesis. Plasma phospholipid 20:4n-6 and 22:6n-3 concentrations are higher in women than in men. We used this sex difference in a lipidomics analysis of the impact of endocrine factors on the phospholipid class and molecular species composition of fasting plasma from young men and women. Diester species predominated in all lipid classes measured. 20/54 Phosphatidylcholine (PtdCho) species were alkyl ester, 15/48 phosphatidylethanolamine (PtdEtn) species were alkyl ester, and 12/48 PtdEtn species were alkenyl ester. There were no significant differences between sexes in the proportions of alkyl PtdCho species. The proportion of alkyl ester PtdEtn species was greater in women than men, while the proportion of alkenyl ester PtdEtn species was greater in men than women. None of the phosphatidylinositol (PtdIns) or phosphatidylserine (PtdSer) molecular species contained ether-linked fatty acids. The proportion of PtdCho16:0_22:6, and the proportions of PtdEtn O-16:0_20:4 and PtdEtn O-18:2_20:4 were greater in women than men. There were no sex differences in PtdIns and PtdSer molecular species compositions. These findings show that plasma phospholipids can be modified by sex. Such differences in lipoprotein phospholipid composition could contribute to sexual dimorphism in patterns of health and disease.</p
Intergroup conflict and dehumanization
No full textThis chapter of the handbook introduces dehumanization as another dark side of humanity. Humanness is a central concept in moral psychology, and whereas people normally treat other humans with moral consideration, they may turn to dehumanize others as a result of moral disengagement and moral exclusion. The author reviews recent psychological accounts of dehumanization that are grounded in empirical research and highlights the diverse forms it takes: dehumanization varies from subtle to blatant, from interpersonal to intergroup, and from simple to complex. In these theoretical accounts, dehumanizing a person or group means ascribing less of certain human attributes to the target – both attributes that distinguish humans from other animals and attributes that distinguish humans from inanimate agents. Within this general framework, the author reviews the empirical literature on how dehumanization may function to prime, facilitate, and justify harm during intergroup conflict. He also considers a number of critiques and debates over these ideas and findings that have recently surfaced
Towards a Theory of Constrained Relativism: Comparing and Combining the Work of Pierre Bourdieu, Mary Douglas and Michael Thompson, and Alan Fiske
No full textIn this article, I seek to compare Pierre Bourdieu\'s theory of practice, the cultural theory developed by Mary Douglas and Michael Thompson, and the relational models theory pioneered by Alan Fiske, and attempt to sketch how these theories could possibly be combined. I argue that the three theories are among the most interesting conceptual enterprises in the social sciences of the last few decades, as they all represent –quite similar– syntheses of long-standing social-science dualisms, such as objectivism vs. subjectivism, social structure vs. free will, functionalism vs. social conflict, etc. Besides these commonalities, I spell out the relative strengths and weaknesses of each of these approaches. This allows me to conclude by considering whether, and how, it might be possible to synthesise these syntheses by picking the most interesting features of the three theories, and avoiding their less appealing ones.[No keywords]
Effects of Fluoride and of Vanadate on Secretion from Electropermeabilized Human Platelets: Relationship to the Activation of Phospholipase D and Phospholipase C
No full textPlatelets permeabilized by high voltage electric discharges have provided a valuable model system in which to analyse the roles of Ca²⁺ ions and guanine nucleotides in the regulation of secretion by exocytosis. In the present study, the effects of fluoride or fluoroaluminate and of vanadate or pervanadate on secretion of platelet dense granule constituents, and the roles of activation of phospholipase D (PLD), phospholipase C (PLC) and protein kinase C (PKC) in secretion, have been investigated. Electropermeabilized human platelets containing [¹⁴C]5-HT in their dense granules were suspended in a glutamate medium containing ATP and incubated for 10 min at 25°C with, variously, Ca²⁺ buffers, KF/AlCl₃, vanadate/H₂O₂, guanine nucleotides and phorbol 12-myristate 13-acetate (PMA). KF/AlCl₃, which activates heterotrimeric G proteins but not low-M, GTP-binding proteins, caused a Ca²⁺ -dependent [¹⁴C]5-HT secretion; maximal effects were obtained with 10 mM KF plus 10 μM AlCl₃ at a pCa of 6, when 53% of [¹⁴C]5-HT was released. Secretion induced by KF/AlCl₃ in the presence of Ca²⁺ correlated with
the stimulation of [3H]diacylglycerol accumulation in permeabilized platelets containing [³H]arachidonate-labelled phospholipids. KF/AlCl₃ also stimulated the phosphorylation of pleckstrin (P47) in permeabilized platelets incubated with [γ-³²P]ATP, indicating the activation of PKC. In the absence of Ca²⁺ (pCa > 9), KF/AlCl₃ caused none of the above effects. These actions of KF/AlCl₃ were attnbutable to the activation of PLC, since KF/AlCl₃ also stimulated the formation of [³H]inositol phosphates in [³H]inositol-labelled permeabilized platelets in the
presence of Ca²⁺. PLD activity, measured as the formation of[³H]phosphatidylethanol (PEt) from [³H]arachidonate-labelled phospholipids in the presence of ethanol, could not be detected after stimulation of platelets by KF/AlCl₃ in the absence or presence of Ca²⁺. However, KF/AlCl₃ inhibited the [³H]PEt formation (PLD activity) induced by GTPγS. In the absence of Ca²⁺ (pCa >9), the inhibitory effects of KF/AlCl₃ on [¹⁴C]5-HT secretion induced by GTPγS alone or GTPγS plus PMA correlated well with their inhibitory effects on [³H]PEt formation. At pCa 6, KF/AlCl₃ had only a small inhibitory effect on GTPγS-induced secretion
and inhibited GTPγS-induced PLD activity more strongly than GTPγS-induced PLC activity. These results suggest that PLD is important for Ca²⁺ -independent secretion, and that, although both PLD and PLC may play roles in Ca²⁺ -dependent secretion, PLC is likely to be the more important. In the presence of Ca²⁺, either vanadate or H₂O₂ caused concentration-dependent stimulations of [¹⁴C]5-HT secretion, [³H]DAG formation and [³H]PEt formation. At pCa 6, low concentrations of vanadate and H₂O₂, which would be expected to form pervanadate, acted synergistically to stimulate [¹⁴C]5-HT secretion, which correlated with [³H]DAG formation. However, vanadate with H₂O₂ had a biphasic effect on PLD activity that did not correlate with secretion. In addition, at pCa 6, GTPγS-induced PLD activity was abolished by vanadate with H₂O₂, whereas GTPγS-induced secretion and PLC activity were only partially inhibited. These results support the idea that both PLC and PLD are involved in the regulation of secretion but have different contributions to Ca²⁺ dependent and Ca²⁺ -independent secretion. The results are consistent with activation of platelet PLC by a heterotrimeric G protein, but suggest that different mechanisms, possibly involving a low-M, GTP-binding protein, may be involved in the regulation of PLD activity.ThesisMaster of Science (MSc
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