The Elusive Backfire Effect Wood, Thomas; Porter, Ethan
Political behavior,
03/2019, Letnik:
41, Številka:
1
Journal Article
Recenzirano
Can citizens heed factual information, even when such information challenges their partisan and ideological attachments? The “backfire effect,” described by Nyhan and Reifler (Polit Behav ...32(2):303–330. https://doi.org/10.1007/s11109-010-9112-2, 2010), says no: rather than simply ignoring factual information, presenting respondents with facts can compound their ignorance. In their study, conservatives presented with factual information about the absence of Weapons of Mass Destruction in Iraq became more convinced that such weapons had been found. The present paper presents results from five experiments in which we enrolled more than 10,100 subjects and tested 52 issues of potential backfire. Across all experiments, we found no corrections capable of triggering backfire, despite testing precisely the kinds of polarized issues where backfire should be expected. Evidence of factual backfire is far more tenuous than prior research suggests. By and large, citizens heed factual information, even when such information challenges their ideological commitments.
The spread of misinformation is a global phenomenon, with implications for elections, state-sanctioned violence, and health outcomes. Yet, even though scholars have investigated the capacity of ...fact-checking to reduce belief in misinformation, little evidence exists on the global effectiveness of this approach. We describe fact-checking experiments conducted simultaneously in Argentina, Nigeria, South Africa, and the United Kingdom, in which we studied whether fact-checking can durably reduce belief in misinformation. In total, we evaluated 22 fact-checks, including two that were tested in all four countries. Fact-checking reduced belief in misinformation, with most effects still apparent more than 2 wk later. A meta-analytic procedure indicates that fact-checks reduced belief in misinformation by at least 0.59 points on a 5-point scale. Exposure to misinformation, however, only increased false beliefs by less than 0.07 points on the same scale. Across continents, fact-checks reduce belief in misinformation, often durably so.
With the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing based on homoserine lactones was found to influence biofilm formation. Here we discern a mechanism by which quorum sensing ...controls biofilm formation by screening 5850 transposon mutants of P. aeruginosa PA14 for altered biofilm formation. This screen identified the PA3885 mutant, which had 147-fold more biofilm than the wild-type strain. Loss of PA3885 decreased swimming, abolished swarming, and increased attachment, although this did not affect production of rhamnolipids. The PA3885 mutant also had a wrinkly colony phenotype, formed pronounced pellicles, had substantially more aggregation, and had 28-fold more exopolysaccharide production. Expression of PA3885 in trans reduced biofilm formation and abolished aggregation. Whole transcriptome analysis showed that loss of PA3885 activated expression of the pel locus, an operon that encodes for the synthesis of extracellular matrix polysaccharide. Genetic screening identified that loss of PelABDEG and the PA1120 protein (which contains a GGDEF-motif) suppressed the phenotypes of the PA3885 mutant, suggesting that the function of the PA3885 protein is to regulate 3,5-cyclic diguanylic acid (c-di-GMP) concentrations as a phosphatase since c-di-GMP enhances biofilm formation by activating PelD, and c-di-GMP inhibits swarming. Loss of PA3885 protein increased cellular c-di-GMP concentrations; hence, PA3885 protein is a negative regulator of c-di-GMP production. Purified PA3885 protein has phosphatase activity against phosphotyrosine peptides and is translocated to the periplasm. Las-mediated quorum sensing positively regulates expression of the PA3885 gene. These results show that the PA3885 protein responds to AHL signals and likely dephosphorylates PA1120, which leads to reduced c-di-GMP production. This inhibits matrix exopolysaccharide formation, which leads to reduced biofilm formation; hence, we provide a mechanism for quorum sensing control of biofilm formation through the pel locus and suggest PA3885 should be named TpbA for tyrosine phosphatase related to biofilm formation and PA1120 should be TpbB.
Highlights • T6SS is a secretion system involved in the virulence of bacterial pathogens. • This versatile weapon can target both prokaryotic and eukaryotic cells. • The T6SS tail/spike displays a ...high modularity for toxin and effector delivery. • The repertoire of T6SS anti-host effectors is used to evade and subvert host defense mechanisms. • T6SS anti-host activity is coordinated with other bacterial virulence factors.
Toxin/antitoxin (TA) systems are present in most prokaryote genomes. Toxins are almost exclusively proteins that reduce metabolism (but do not cause cell death), and antitoxins are either RNA or ...proteins that counteract the toxin or the RNA that encodes it. Although TA systems clearly stabilize mobile genetic elements, after four decades of research, the physiological roles of chromosomal TA systems are less clear. For example, recent reports have challenged the notion of TA systems as stress-response elements, including a role in creating the dormant state known as persistence. Here, we present evidence that a primary physiological role of chromosomally encoded TA systems is phage inhibition, a role that is also played by some plasmid-based TA systems. This includes results that show some CRISPR-Cas system elements are derived from TA systems and that some CRISPR-Cas systems mimic the host growth inhibition invoked by TA systems to inhibit phage propagation.
Stress is ubiquitous for bacteria and can convert a subpopulation of cells into a dormant state known as persistence, in which cells are tolerant to antimicrobials. These cells revive rapidly when ...the stress is removed and are likely the cause of many recurring infections such as those associated with tuberculosis, cystic fibrosis, and Lyme disease. However, how persister cells are formed is not understood well. Here we propose the ppGpp ribosome dimerization persister (PRDP) model in which the alarmone guanosine pentaphosphate/tetraphosphate (henceforth ppGpp) generates persister cells directly by inactivating ribosomes via the ribosome modulation factor (RMF), the hibernation promoting factor (Hpf), and the ribosome-associated inhibitor (RaiA). We demonstrate that persister cells contain a large fraction of 100S ribosomes, that inactivation of RMF, HpF, and RaiA reduces persistence and increases single-cell persister resuscitation and that ppGpp has no effect on single-cell persister resuscitation. Hence, a direct connection between ppGpp and persistence is shown along with evidence of the importance of ribosome dimerization in persistence and for active ribosomes during resuscitation.
•ppGpp generates persister cells directly without toxin/antitoxin systems.•ppGpp inactivates ribosomes by stimulating ribosome modulators RMF, Hpf, and RaiA.•Persister cells contain a large fraction of inactive 100S ribosomes.
A number of bacteria, and some plants, produce large quantities of indole, which is widespread in animal intestinal tracts and in the rhizosphere. Indole, as an interspecies and interkingdom ...signaling molecule, plays important roles in bacterial pathogenesis and eukaryotic immunity. Furthermore, indole and its derivatives are viewed as potential antivirulence compounds against antibiotic-resistant pathogens because of their ability to inhibit quorum sensing and virulence factor production. Indole modulates oxidative stress, intestinal inflammation, and hormone secretion in animals, and it controls plant defense systems and growth. Insects and nematodes can recognize indole, which controls some of their behavior. This review presents current knowledge regarding indole and its derivatives, their biotechnological applications and their role in prokaryotic and eukaryotic systems.
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