Summary mi RNA s contribute to plant resistance against pathogens. Previously, we found that the function of miR398b in immunity in rice differs from that in Arabidopsis. However, the underlying mechanisms are unclear. In this study, we characterized the mutants of miR398b target genes and demonstrated that multiple superoxide dismutase genes contribute to miR398b‐regulated rice immunity against the blast fungus Magnaporthe oryzae . Out of the four target genes of miR398b, mutations in Cu/Zn‐Superoxidase Dismutase1 ( CSD 1 ), CSD 2 and Os11g09780 ( Superoxide DismutaseX , SODX ) led to enhanced resistance to M. oryzae and increased hydrogen peroxide (H 2 O 2 ) accumulation. By contrast, mutations in Copper Chaperone for Superoxide Dismutase ( CCSD ) resulted in enhanced susceptibility. Biochemical studies revealed that csd1 , csd2 and sodx displayed altered expression of CSD s and other superoxide dismutase ( SOD ) family members, leading to increased total SOD enzyme activity that positively contributed to higher H 2 O 2 production. By contrast, the ccsd mutant showed CSD protein deletion, resulting in decreased CSD and total SOD enzyme activity. Our results demonstrate the roles of different SOD s in miR398b‐regulated resistance to rice blast disease, and uncover an integrative regulatory network in which miR398b boosts total SOD activity to upregulate H 2 O 2 concentration and thereby improve disease resistance.

Background To determine if global brain hypoperfusion and oxygen hypometabolism occur in patients with amnestic mild cognitive impairment (aMCI). Methods Thirty-two aMCI and 21 normal subjects participated. Total cerebral blood flow (TCBF), cerebral metabolic rate of oxygen (CMRO2) and brain tissue volume were measured using color-coded duplex ultrasonography (CDUS), near-infrared spectroscopy (NIRS), and MRI. TCBF was normalized by total brain tissue volume (TBV) for group comparisons (nTCBF). Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by TCBF. Results Reductions in nTCBF by 9%, CMRO2 by 11%, and increase in CVR by 13% were observed in aMCI relative to normal subjects. No group differences in TBV were observed. nTCBF was correlated with CMRO2 in normal controls, but not in aMCI. Conclusions Global brain hypoperfusion, oxygen hypometabolism and neurovascular decoupling observed in aMCI suggest that changes in cerebral hemodynamics occur early at prodromal stage of Alzheimer’s disease, which can be assessed using low cost and bed-side available CDUS and NIRS technology.

Physical activity may influence cerebrovascular function. The objective of this study was to determine the impact of life-long aerobic exercise training on cerebral vasomotor reactivity (CVMR) to changes in end-tidal CO2 (EtCO2) in older adults. Eleven sedentary young (SY, 27 ± 5 years), 10 sedentary elderly (SE, 72 ± 4 years), and 11 Masters athletes (MA, 72 ± 6 years) underwent the measurements of cerebral blood flow velocity (CBFV), arterial blood pressure, and EtCO2 during hypocapnic hyperventilation and hypercapnic rebreathing. Baseline CBFV was lower in SE and MA than in SY while no difference was observed between SE and MA. During hypocapnia, CVMR was lower in SE and MA compared with SY (1.87 ± 0.42 and 1.47 ± 0.21 vs. 2.18 ± 0.28 CBFV%/mm Hg, Po0.05) while being lowest in MA among all groups (Po0.05). In response to hypercapnia, SE and MA exhibited greater CVMR than SY (6.00 ± 0.94 and 6.67 ± 1.09 vs. 3.70 ± 1.08 CBFV1%/mm Hg, Po0.05) while no difference was observed between SE and MA. A negative linear correlation between hypo-and hypercapnic CVMR (R 2 ¼ 0.37, Po0.001) was observed across all groups. Advanced age was associated with lower resting CBFV and lower hypocapnic but greater hypercapnic CVMR. However, life-long aerobic exercise training appears to have minimal effects on these age-related differences in cerebral hemodynamics.

Brassinosteroids (BRs) play an essential role in plant growth and development, and have been implicated in many physiological responses. However, little is known about the role of BRs in the plant response to oxidative stress. In this study, we identified a novel insertion allele (det2-9) of the DET2 gene in Arabidopsis based on molecular, physiological and genetic approaches. We found that the det2 mutant exhibited an enhanced resistance to oxidative stress. The enhanced oxidative stress resistance in det2 plants was correlated with a constitutive increase in superoxide dismutase (SOD) activity and increased transcript levels of the defence gene catalase (CAT). To our knowledge, these results demonstrate, for the first time, that loss-of-function mutations in the DET2 gene lead to an enhanced oxidative stress resistance in Arabidopsis. A general explanation is that the long-term BR deficiency in the det2 mutant results in a constant in vivo physiological stress that, in turn, activates the constitutive expression of some defence genes and, consequently, the activities of related enzymes.

MicroRNAs (miRNAs) play important roles in rice response to Magnaporthe oryzae, the causative agent of rice blast disease. Studying the roles of rice miRNAs is of great significance for the disease control. Osa-miR167d belongs to a conserved miRNA family targeting auxin responsive factor (ARF) genes that act in developmental and stress-induced responses. Here, we show that Osa-miR167d plays a negative role in rice immunity against M. oryzae by suppressing its target gene. The expression of Osa-miR167d was significantly suppressed in a resistant accession at and after 24 h post inoculation (hpi), however, its expression was significantly increased at 24 hpi in the susceptible accession upon M. oryzae infection. Transgenic rice lines over-expressing Osa-miR167d were highly susceptible to multiple blast fungal strains. By contrast, transgenic lines expressing a target mimicry to block Osa-miR167d enhanced resistance to rice blast disease. In addition, knocking out the target gene ARF12 led to hypersusceptibility to multiple blast fungal strains. Taken together, our results indicate that Osa-miR167d negatively regulate rice immunity to facilitate the infection of M. oryzae by downregulating ARF12. Thus, Osa-miR167d-ARF12 regulatory module could be valuable in improvement of blast-disease resistance.

Fitness cost is a common phenomenon in rice blast disease-resistance breeding. MiR396 is a highly conserved microRNA (miRNA) family targeting Growth Regulating Factor (OsGRF) genes. Mutation at the target site of miR396 in certain OsGRF gene or blocking miR396 expression leads to increased grain yield. Here we demonstrated that fitness cost can be trade-off in miR396-OsGRFs module via balancing growth and immunity against the blast fungus. The accumulation of miR396 isoforms was significantly increased in a susceptible accession, but fluctuated in a resistant accession upon infection of Magnaporthe oryzae. The transgenic lines over-expressing different miR396 isoforms were highly susceptible to M. oryzae. In contrast, overexpressing target mimicry of miR396 to block its function led to enhanced resistance to M. oryzae in addition to improved yield traits. Moreover, transgenic plants overexpressing OsGRF6, OsGRF7, OsGRF8, and OsGRF9 exhibited enhanced resistance to M. oryzae, but showed different alteration of growth. While overexpression of OsGRF7 led to defects in growth, overexpression of OsGRF6, OsGRF8, and OsGRF9 resulted in better or no significant change of yield traits. Collectively, our results indicate that miR396 negatively regulates rice blast disease- resistance via suppressing multiple OsGRFs, which in turn differentially control growth and yield. Therefore, miR396-OsGRFs could be a potential module to demolish fitness cost in rice blast disease-resistance breeding.

C erebral autoregulation (CA) is essential to maintain a constant cerebral blood flow (CBF) in the context of changes in cerebral perfusion pressure.1 Assessment of CA reflects cerebrovascular function and has been used widely in hypertension studies and other clinical settings. 2,3 Quantitative assessment of CA is challenged by the methods used for CBF measurement. Modern imaging modalities such as single-photon emission computed tomography, positron emission tomography, perfusion computed tomography, and MRI are difficult to be applied for CBF measurement in clinical studies of CA because of the cumbersome experimental conditions, the limitations of using radioactive isotopes (single-photon emission computed tomography and positron emission tomography), or other imaging contrast agents (computed tomography and MRI) for repeated measurements. 4 Recently, transcranial Doppler (TCD) has been used to assess CA because of its bedside availability, noninvasiveness, and high temporal resolution in measuring changes in cerebral blood flow velocity (CBFV) in the basal cerebral arteries. 5 However, because the diameter of the insonated vessels cannot be measured directly using TCD, the validity of using this technique to assess CA is based on a fundamental assumption that changes in CBFV represent changes in volumetric CBF, that is, by assuming that the diameter of basal cerebral arteries does not change significantly in the face of changes in blood pressure. 5 For its importance, this assumption has been evaluated repeatedly by using a variety of imaging modalities to measure CBF and to compare with TCD measurement of CBFV during changes in arterial pressure. 6,7 However, the findings so far are inconsistent. [8][9][10] One of the major limitations of these studies is that CBF and CBFV often were not measured simultaneously or were measured with different temporal and spatial resolutions, thus making it difficult or even impossible for direct comparisons between CBF and CBFV Abstract-The validity of using transcranial Doppler measurement of cerebral blood flow velocity (CBFV) to assess cerebral autoregulation (CA) still is a concern. This study measured CBFV in the middle cerebral artery using transcranial Doppler and volumetric cerebral blood flow (CBF) in the internal carotid artery (ICA) using color-coded duplex ultrasonography to assess CA during steady-state changes in mean arterial pressure (MAP 7 However, this study was conducted only in 7 patients with cerebrovascular diseases under surgical conditions, and these observations need to be confirmed.Color-coded duplex ultrasonography (CDUS) is a noninvasively bedside available technology that has been used to measure volumetric CBF in the ICA.12,13 Similar to TCD, CDUS also has high temporal resolution.14 In addition, changes in CBF in the ICA most likely reflect those in the MCA and anterior cerebral artery, which are the major branches of ICA.In this study, we simultaneously measured changes in CBFV in the MCA and ICA and CBF in the ICA to assess CA during stepw...

GeSe is a IV-VI semiconductor, like the excellent thermoelectric materials PbTe and SnSe. Orthorhombic GeSe has been predicted theoretically to have good thermoelectric performance but is difficult to dope experimentally. Like PbTe, rhombohedral GeTe has a multivalley band structure, which is ideal for thermoelectrics and also promotes the formation of Ge vacancies to provide enough carriers for electrical transport. Herein, we investigate the thermoelectric properties of GeSe alloyed with AgSbSe , which stabilizes a new rhombohedral structure with higher symmetry that leads to a multivalley Fermi surface and a dramatic increase in carrier concentration. The zT of GeAg Sb Se reaches 0.86 at 710 K, which is 18 times higher than that of pristine GeSe and over four times higher than doped orthorhombic GeSe. Our results open a new avenue towards developing novel thermoelectric materials through crystal phase engineering using a strategy of entropy stabilization of high-symmetry alloys.