RESUMO
Polyamines are ubiquitous biomolecules with a number of established functions in eukaryotic cells. In plant cells, polyamines have previously been linked to abiotic and biotic stress tolerance, as well as to the modulation of programmed cell death (PCD), with contrasting reports on their pro-PCD and pro-survival effects. Here, we used two well-established platforms for the study of plant PCD, Arabidopsis thaliana suspension cultures cells and the root hair assay, to examine the roles of the polyamines spermine and spermidine in the regulation of PCD. Using these systems for precise quantification of cell death rates, we demonstrate that both polyamines can trigger PCD when applied exogenously at higher doses, whereas at lower concentrations they inhibit PCD induced by both biotic and abiotic stimuli. Furthermore, we show that concentrations of polyamines resulting in inhibition of PCD generated a transient ROS burst in our experimental system, and activated the expression of oxidative stress- and pathogen response-associated genes. Finally, we examined PCD responses in existing Arabidopsis polyamine synthesis mutants, and identified a subtle PCD phenotype in Arabidopsis seedlings deficient in thermo-spermine. The presented data show that polyamines can have a role in PCD regulation; however, that role is dose-dependent and consequently they may act as either inhibitors, or inducers, of PCD in Arabidopsis.
RESUMO
Low back pain (LBP) is the most commonly reported musculoskeletal disorder (MSD) among farmers. There is limited researching regarding the lived experience of LBP among farmers. Video interviews were conducted with three dairy farmers who reported having a significant episode of LBP. The interview data were transcribed and analyzed, and results were presented in relation to the constructs explored. The farmers experienced their first significant episode of LBP in their late 20s or early 30s and all attributed their LBP to farm work or a farm-related incident. Hours worked per day ranged from 9 to 13 hours. Tasks identified by farmers that they were unable to do due to LBP included physical work, working with sheep, building work, and "certain jobs." Work changes made due to LBP included getting help, slowing down, avoiding strenuous work, carrying smaller loads, mechanizing the farm, using the tractor more, and wearing a back belt for certain jobs. Each farmer had his own way of preventing or managing his LBP, including a mix of active self-management and passive coping strategies such as swimming, using ice, spinal manipulation, and taking medication. The farmers were unable to quantify how much their LBP had cost them directly or indirectly. The case studies illustrate farmers engaging in ongoing work despite significant pain. All of the farmers have adapted at work and engaged in self-management strategies to reduce the occurrence of LBP. Given the rich data produced by these case studies, future case studies are recommended to gain greater insights into farmers' experiences concerning LBP.
