230 research outputs found
Genetic dissection of nitric oxide signalling network In plant defence response
Following pathogen recognition, nitric oxide (NO) is rapidly produced in plants, this
small molecule has emerged as a key signal in plant defence responses. S-nitrosylation
is the major route of NO signal transduction in plants, a redox-based
modification by addition of an NO moiety on cysteine thiol to form an S-nitrosothiol
(SNO). S-nitrosoglutathione reductase (GSNOR) regulates cellular levels of S-nitrosylation
and displays a key role in regulating the plant defence response. In this
context, NO is important to orchestrate both defence gene expression and the
hypersensitive response (HR) during attempted microbial infection. However, how
the plant immune system recognizes NO and how NO level could elicit plant defence
responses are poorly understood.
The Arabidopsis thaliana (Arabidopsis) mutant NO overproducing 1 (nox1) was
employed to characterize how NO level elicits defence dynamics. In response to
microbial infection, resistance (R) gene-mediated defence and basal resistance were
found to be compromised in the nox1 mutant relative to wild type Col-0 plants.
Interestingly, nox1 mutant exhibit similar levels of HR and pathogen susceptibility to
the GSNOR loss-of-function mutant atgsnor1-3. This phenomenon suggests that NO
might regulate defence responses via GSNOR-mediated S-nitrosylation. Therefore,
the nox1 atgsnor1-3 double mutant was generated and characterized to clarify this
hypothesis. Accelerated HR and increased pathogen susceptibility are shown in the
double mutant, which implies that increased NO mediated by nox1 and elevated
SNOs resulting from atgsnor1-3, are additive with respect to the plant defence
response.
To identify genes responsible for NO perception, forward genetic screens were
developed to identify Arabidopsis mutants with abnormal NO recognition. NO
marker genes for genetic screens were identified from both lab and open source
microarray data. Two genes, At3g28740 and At1g76600 were selected and
experimentally confirmed to be strongly induced by NO. Transgenic Arabidopsis
plants were generated carrying a NO reporter cassette, which consist of a luciferase
reporter gene (LUC) driven by the promoter of NO marker gene. This forward
genetic approach might be a powerful tool to identify genes integral to NO signal
transduction.
Three C2H2 zinc finger transcription factors (ZnTFs) ZAT7, ZAT8 and ZAT12 were
identified as being rapidly and strongly induced by NO donors, which could be
modulators of redox/NO-dependent signalling pathway. T-DNA insertion mutants
within these ZnTFs have been identified. Basal resistance against Pseudomonas
syringae pv tomato (Pst) DC3000 is compromised in all single knockout lines.
Therefore, the full characterisation of defence phenotype of these mutants would be
necessary to explore the role of these TFs in the plant defence. Furthermore, zat8
mutant is more sensitive to nitrosative stress when compared to wild type Col-0. This
suggests that ZAT8 may be involved in protecting plants against nitrosative stress.
However, the molecular mechanisms that underpin this function remain to be
determined.
In conclusion, NO and SNOs might regulate plant disease resistance via distinct
pathways. Our work has also established NO-reporter lines to identify genes
responsible for NO perception. In addition, three NO-induced ZnTFs have been
identified that participate in regulation of basal resistance, which might unveil
aspects of NO signalling related to the regulation of transcription
Day-to-day Traffic Dynamics with Strategic Commuters
In the era of connected and automated mobility, commuters (connected drivers
or automated vehicles) will possess strong computation capability and their
travel decisions can be algorithmic and strategic. This paper investigates the
day-to-day travel choice evolution of such strategic commuters who are capable
of long-term planning and computation. We model the commute problem as a mean
field game and examine the mean field equilibrium to derive the evolution of
the network traffic flow pattern. The proposed model is general and can be
tailored to various travel choices such as route or departure time. Under
various conditions, we prove the existence and uniqueness of the day-to-day
equilibrium traffic evolution pattern as well as its convergence to
stationarity. Connection with traditional Wardropian equilibrium is established
by examining the physical interpretation of the stationary solution
Gaussian Distribution-Based Inertial Control of Wind Turbine Generators for Fast Frequency Response in Low Inertia Systems
Decline of rotating inertia due to the high share of renewable sources cause challenges in controlling grid frequency. With recent grid codes, large-scale wind turbines (WTs) are required to provide frequency support. Existing stepwise inertial control methods suggest immediate incremental power injection by WTs, followed by the abrupt over-production termination to avoid over-deceleration of the rotor speed. Unfortunately, these methods are not practically desirable as they impose severe secondary-frequency-drops (SFD) or considering unrealistic constant wind speed for tens of seconds. This paper proposes a novel inertial control scheme that can improve frequency nadir without rotor speed over-deceleration. Upon detecting a power imbalance, WT increases the output power with an incremental power and declines it following a Gaussian distribution trajectory controlled by a standard deviation parameter, to ensure convergence to an equilibrium point. The proposed scheme can be practically implemented for fast frequency response. This scheme is tested on the wind-integrated IEEE 9-bus system and IEEE 39-bus system and compared with other methods reported in literature. Furthermore, experimental tests are conducted to verify the performance of the proposed scheme in practice. Blade fatigue is studied using FAST Code. Results show reliable operation during abrupt wind speed changes or cascade events
Pion and kaon electromagnetic and gravitational form factors
A unified set of predictions for pion and kaon elastic electromagnetic and
gravitational form factors is obtained using a symmetry-preserving truncation
of each relevant quantum field equation. A key part of the study is a
description of salient aspects of the dressed graviton + quark vertices. The
calculations reveal that each meson's mass radius is smaller than its charge
radius, matching available empirical inferences; and meson core pressures are
commensurate with those in neutron stars. The analysis described herein paves
the way for a direct calculation of nucleon gravitational form factors.Comment: 12 pages, 4 figures, 3 table
METABOLIC CHANGES INDUCED BY BUSHENHUOXUE GRANULES ON STRIATUM AND SUBSTANTIA NIGRA IN A RAT MODEL OF PARKINSON’S DISEASE
Background: Parkinson’s disease is a neurodegenerative disease, while its mechanism is still unclear. Long-term levodopa-based treatment leads to decreased response or loss of response, as well as severe side effects. Our previous study has proved that Bushenhuoxue Granules have effects on Parkinson’s disease, but the underlying mechanism is still need to be explored. Our research is to investigate the mechanisms of Bushenhuoxue Granules on Parkinson’s disease (PD) by examining changes in the expression of the adenosine A2A receptor、vesicular monoamine transporter 2 (VMAT2)、divalent metal transporter 1(DMT1) and nuclear factor E2 related (Nrf2) in a rat model of Parkinson’s disease (PD) .
Materials and Methods: Changes in the apomorphine (APO)-induced rotational behavior of rats were observed after treatment. Immunofluorescence and immunohistochemistry were performed to investigate changes in adenosine A2A receptor 、VMAT2、DMT1 and Nrf2 expression in the rat striatum and substantia nigra.
Results: Rotations after treatment were199.11 ± 27.16, which significantly decreased compared with that before treatment ( 273.0 ± 44.61, p < 0.01). Adenosine A2A receptor expression in the striatum was 3.10 ± 0.34 significantly increased in the model group and decreased in the normal control group, whereas the expression level in the Bushenhuoxue group was 1.13 ± 0.23,p < 0.05 between the two control groups. No adenosine A2A receptor expression was observed in the substantia nigra. VMAT2 expression in the rat striatum was 23.20 ± 2.68 and substantia nigra was 15.98 ± 0.70 increased in the normal control group. They were 8.99 ± 0.48 in the rat striatum and 8.45 ± 0.59 substantia nigra significantly decreased in the model control group, whereas the expression level in the Bushenhuoxue group was 15.36 ± 0.89 in the rat striatum and 11.69 ± 1.17 in the rat substantia nigra (p < 0.05), also between the two control groups. DMT1 expression in the rat striatum was 3.30 ± 0.30 and substantia nigra was 6.56 ± 0.64 decreased in the normal control group. They were 7.92 ± 0.52 in the rat striatum and 12.76 ± 0.86 substantia nigra significantly increased in the model control group, whereas the expression level in the Bushenhuoxue group was 6.17 ± 0.27 in the rat striatum and 9.13 ± 0.44 in the rat substantia nigra (p < 0.05), also between the two control groups. Nrf2 expression in the rat striatum was 7.90 ± 0.29 and substantia nigra was 15.22 ± 1.22 increased in the normal control group. They were 3.09 ± 0.43 in the rat striatum and 8.57 ± 0.54 substantia nigra significantly decreased in the model control group, whereas the expression level in the Bushenhuoxue group was 5.00 ± 0.34 in the rat striatum and 12.46 ± 0.62 in the rat substantia nigra (p< 0.05), also between the two control groups. Conclusion: Bushenhuoxue Granules significantly improved the rotational behavior of PD’s rats, decreased adenosine A2A receptor expression, and increased VMAT2 expression; decreased DMT1 expression, and increased Nfr2 expression
Influence of steric hindrance on the molecular packing and the anchoring of quinonoid zwitterions on gold surfaces
Driven by the huge potential of engineering the molecular band offset with highly dipolar molecules for improving charge injection into organic electrics, the anchoring of various N-alkyl substituted quinonoid zwitterions of formula C6H2 (···NHR)2 (···O)2 (R = iPr, Cy, CH2CH(Et)CH2CH2CH2CH3,. . .) on gold surfaces is studied. The N–Au interactions result in an orthogonal arrangement of the zwitterions cores with respect to the surface, and stabilize adsorbed compact rows of molecules. IR spectroscopy is used as a straightforward diagnostic tool to validate the presence of ultra-thin molecular films. When combined with computational studies, IR measurements indicate that the presence of a CH2group in α position to the nitrogen atom is important for a successful anchoring through N–Au interactions. The presence of such a flexible CH2 spacer, or of aryl groups, enables π-interactions with the surface, making possible the anchoring of enantiopure or sterically-hindered zwitterions. X-ray diffraction analyses indicate that the intermolecular spacing within a row of molecules can be modulated by the nature of the alkyl substituent R. This modulation is directly relevant to the electronic properties of the corresponding molecular films since these zwitterions are expected to form rows on gold surfaces similar to those observed in the bulk crystalline state
Thermal-Enhanced bri1-301 Instability Reveals a Plasma Membrane Protein Quality Control System in Plants
Brassinosteroids (BRs) are essential phytohormones mainly perceived by a single-pass transmembrane receptor-like protein kinase (RLK), BRASSINOSTEROID INSENSITIVE 1 (BRI1). bri1-5 and bri1-9, two distinct mutants with point mutations in the extracellular domain of BRI1, show weak defective phenotypes. Previous studies indicated that bri1-5 and bri1-9 mutated proteins can be recognized and eliminated via an endoplasmic reticulum quality control (ERQC) mechanism. Most of these two proteins, therefore, cannot reach their destination, plasma membrane. Here, we report our functional characterization of bri1-301, another BRI1 mutant protein with an amino acid substitution in the cytoplasmic kinase domain. bri1-301 is a partially functional BR receptor with significantly decreased protein abundance. Interestingly, protein stability and subcellular localization of bri1-301 are temperature-sensitive. At 22°C, an optimal temperature for indoor Arabidopsis growth, bri1-301 shows a weak defective phenotype. At a lower temperature condition such as 18°C, bri1-301 exhibits subtle morphological defects. At a higher temperature condition such as 28°C, on the other hand, bri1-301 displays an extremely severe phenotype reminiscent to that of a null bri1 mutant due to greatly increased bri1-301 internalization and degradation. Our detailed analyses suggest that bri1-301 stability is controlled by ERQC and plasma membrane quality control (PMQC) systems. Since PMQC has not been well studied in plants, bri1-301 can be used as a model mutant for future genetic dissection of this critical process
The efficacy of botulinum toxin type A treatment and surgery for acute acquired comitant esotropia
AimTo compare the long-term efficiency of botulinum toxin type A (BTXA) injection and surgery on acute acquired comitant esotropia (AACE).MethodsThis retrospective study enrolled patients with AACE from January 2020 to August 2022. The horizontal angle of deviation pre- and post-treatment was measured. Deviations in BTXA and surgical treatment were compared. The BTXA group was divided into adequate treatment (AT) and inadequate treatment (inAT) subgroup based on the deviation of no more than 4 prism diopters (at near and distance) or temporary exotropia at the 2 week follow-up. The two subgroups were compared to determine the long-term efficacy of BTXA treatment.ResultsNinety-two patients with AACE were included. Follow-up was 6 months. The deviations of the surgery and BTXA group were significantly smaller at the 6 month follow-up than at pre-treatment (p < 0.001). The deviation before treatment in the surgery group was larger than in the BTXA groups (p < 0.001) but smaller at the 6 month follow-up (p < 0.001). The deviation was similar in the AT-BTXA and inAT-BTXA subgroups before treatment (p = 0.322 for distance and p = 0.051 for near) but smaller in the AT-BTXA subgroup at 6 month follow-up (p < 0.001 for near and distance).ConclusionSurgery and BTXA successfully treat AACE. Surgery has a more precise and lasting therapeutic effect than BTXA. AACE patients adequately treated with BTXA and with deviations of no more than 4 prism diopters at 2 weeks follow-up had better outcomes
Invasive alien plants are phylogenetically distinct from other alien species across spatial and taxonomic scales in China
IntroductionPhylogenetic relatedness is one of the important factors in the community assembly process. Here, we aimed to understand the large-scale phylogenetic relationship between alien plant species at different stages of the invasion process and how these relationships change in response to the environmental filtering process at multiple spatial scales and different phylogenetic extents.MethodsWe identified the alien species in three invasion stages, namely invasive, naturalized, and introduced, in China. The occurrence records of the species were used to quantify two abundance-based phylogenetic metrics [the net relatedness index (NRI) and the nearest taxon index (NTI)] from a highly resolved phylogenetic tree. The metrics were compared between the three categories of alien species. Generalized linear models were used to test the effect of climate on the phylogenetic pattern. All analyses were conducted at four spatial scales and for three major angiosperm families.ResultsWe observed significantly higher NRI and NTI values at finer spatial scales, indicating the formation of more clustered assemblages of phylogenetically closely related species in response to the environmental filtering process. Positive NTI values for the invasive and naturalized aliens suggested that the presence of a close relative in the community may help the successful naturalization and invasion of the introduced alien species. In the two-dimensional phylogenetic space, the invasive species communities significantly differed from the naturalized and introduced species, indicating that established alien species need to be phylogenetically different to become invasive. Positive phylogenetic measures for the invasive aliens across the spatial scales suggested that the presence of invasive aliens could facilitate the establishment of other invasive species. Phylogenetic relatedness was more influenced by temperature than precipitation, especially at a finer spatial scale. With decreased temperature, the invasive species showed a more clustered assemblage, indicating conservatism of their phylogenetic niche. The phylogenetic pattern was different at the family level, although there was a consistent tendency across families to form more clustered assemblages.DiscussionOverall, our study showed that the community assemblage became more clustered with the progression of the invasion process. The phylogenetic measures varied at spatial and taxonomic scales, thereby highlighting the importance of assessing phylogenetic patterns at different gradients of the community assembly process
- …