Signal Regulators of Systemic Acquired Resistance

Salicylic acid (SA) is an important phytohormone that plays a vital role in a number of physiological responses, including plant defense. The last two decades have witnessed a number of breakthroughs related to biosynthesis, transport, perception and signaling mediated by SA. These findings demonstrate that SA plays a crictical role in both local and systemic defense responses. Systemic acquired resistance (SAR) is one such SA-dependent response. SAR is a long distance signaling mechanism that provides broad spectrum and long-lasting resistance to secondary infections throughout the plant. This unique feature makes SAR a highly desirable trait in crop production. This review summarizes the recent advances in the role of SA in SAR and discusses its relationship to other SAR inducers

Anaerobic expression of the gadE-mdtEF multidrug efflux operon is primarily regulated by the two-component system ArcBA through antagonizing the H-NS mediated repression

The gadE-mdtEF operon encodes a central acid resistance regulator GadE and two multidrug efflux proteins MdtEF. Although transcriptional regulation of gadE in the context of acid resistance under the aerobic growth environment of E. coli has been extensively studied, regulation of the operon under the physiologically relevant environment of anaerobic growth and its effect on the expression of the multidrug efflux proteins MdtEF has not been disclosed. Our previous study revealed that anaerobic induction of the operon was dependent on ArcA, the response regulator of the ArcBA two-component system, in the M9 glucose minimal medium. However, the detailed regulatory mechanism remains unknown. In this study, we showed that anaerobic activation of mdtEF was driven by the 798bp unusually long gadE promoter. Deletion of evgA, ydeO, rpoS, and gadX which has been shown to activate the gadE expression during acid stresses under aerobic condition did not have a significant effect on the anaerobic activation of the operon. Rather, anaerobic activation of the operon was largely dependent on the global regulator ArcA and a GTPase MnmE. Under aerobic condition, transcription of gadE was repressed by the global DNA silencer H-NS in M9 minimal medium. Interestingly, under anaerobic condition, while ΔarcA almost completely abolished transcription of gadE-mdtEF, further deletion of hns in ΔarcA mutant restored the transcription of the full length PgadE-lacZ, and P1- and P3-lacZ fusions, suggesting an antagonistic effect of ArcA on the H-NS mediated repression. Taken together, we conclude that the anaerobic activation of the gadE-mdtEF was primarily mediated by the two-component system ArcBA through antagonizing the H-NS mediated repression

Extraversion and Neuroticism relate to topological properties of resting-state brain networks

With the advent and development of modern neuroimaging techniques, there is an increasing interest in linking extraversion and neuroticism to anatomical and functional brain markers. Here we aimed to test the theoretically derived biological personality model as proposed by Eysenck using graph theoretical analyses. Specifically, the association between the topological organization of whole-brain functional networks and extraversion/neuroticism was explored. To construct functional brain networks, functional connectivity among 90 brain regions was measured by temporal correlation using resting-state functional magnetic resonance imaging (fMRI) data of 71 healthy subjects. Graph theoretical analysis revealed a positive association of extraversion scores and normalized clustering coefficient values. These results suggested a more clustered configuration in brain networks of individuals high in extraversion, which could imply a higher arousal threshold and higher levels of arousal tolerance in the cortex of extraverts. On a local network level, we observed that a specific nodal measure, i.e. betweenness centrality (BC), was positively associated with neuroticism scores in the right precentral gyrus, right caudate nucleus, right olfactory cortex and bilateral amygdala. For individuals high in neuroticism, these results suggested a more frequent participation of these specific regions in information transition within the brain network and, in turn, may partly explain greater regional activation levels and lower arousal thresholds in these regions. In contrast, extraversion scores were positively correlated with BC in the right insula, while negatively correlated with BC in the bilateral middle temporal gyrus, indicating that the relationship between extraversion and regional arousal is not as simple as proposed by Eysenck

Lower bone mineral density in Patients with Parkinson’s disease: a cross-sectional study from Chinese Mainland

Objectives Although several lines of evidence have suggested that patients with Parkinson’s disease (PD) have a higher risk of osteoporosis and fracture, the association between bone mineral density and severity of PD patients is unknown. Methods We performed a cross-sectional study of 54 patients with PD and 59 healthy age-matched controls. Multiple clinical scales were used to evaluate the severity of PD, and serum levels of calcium, phosphorus, and homocysteine were measured to determine bone mineral density’s association with PD severity. Results BMD in PD patients was significantly lower than in healthy controls. The BMD scores of the spine, femoral neck, and hip were lower in females than in males in the healthy group. In the PD group, BMD in the hip was significantly lower in females compared to males. There was a negative correlation between daily L-dopa dosage and BMD in the spine and hip in the PD group, while BMD in the spine, neck, and hip was significantly correlated with severity of PD. Besides, we found that among the lumbar spine, femoral neck and hip, bone loss in the lumbar spine was the most severe in PD patients based on the T-scores. Conclusions Our findings support the hypothesis that patients with PD have a higher risk of osteoporosis, and that low BMD in the spine, femoral neck, and hip may indirectly reflect the severity of PD. Our findings have prompted us to pay more attention to osteoporosis in the lumbar spine in Chinese PD patients