O-Carboxymethyl chitosan nanoparticles: A novel approach to enhance water stress tolerance in maize seedlings.

Water stress, a significant abiotic stressor, significantly hampers crop growth and yield, posing threat to food security. Despite the promising potential of nanoparticles (NPs) in enhancing plant stress tolerance, the precise mechanisms underlying the alleviation of water stress using O-Carboxymethyl chitosan nanoparticles (O-CMC-NPs) in maize remain elusive. In this study, we synthesized O-CMC-NPs and delved into their capacity to mitigate water stress (waterlogging and drought) in maize seedlings. Structural characterization revealed spherical O-CMC-NPs with a size of approximately 200 nm. These NPs accumulated near the seed embryo and root tip, resulting in a substantial increase in fresh and dry weights. The application of O-CMC-NPs to water-stressed maize seedlings remarkedly elevated the chlorophyll content and activity of various antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO). The malondialdehyde (MDA) content was significantly reduced compared to the untreated control. Additionally, the expression of stress-responsive genes, such as ZmSOD, ZmCAT, ZmPOD, ZmTIFY, ZmACO, ZmPYL2, ZmNF-YC12, and ZmEREB180, were significantly upregulated in the O-CMC-NPs treated seedlings. These findings unveil the novel role of O-CMC-NPs in enhancing plant stress tolerance, suggesting their potential application in safeguarding maize seedlings under water stress conditions and facilitating the recovery from oxidative damage.

Integrated LC-MS and GC-MS-based untargeted metabolomics studies of the effect of azadirachtin on Bactrocera dorsalis larvae.

Azadirachtin exhibits excellent bioactivities against several hundred arthropods. However, current knowlege of its biochemical effect on B. dorsalis larvae is not deep enough. In this study, integrated LC-MS and GC-MS-based untargeted metabolomics were used to analyze the changes of endogenous metabolites and the biochemical effects of azadirachtin on B. dorsalis larvae. Azadirachtin has excellent bioactivities against B. dorsalis larvae in this study, leading to a longer developmental duration, lower survival rate, and low pupa weight. The effect of azadirachtin was investigated on a total of 22 and 13 differentially abundant metabolites in the LC-MS and GC-MS-based metabolomics results, are selected respectively. Pathway analysis indicated that 14 differentially enriched metabolic pathways, including seven influential pathways, are worthy of attention. Further integrated key metabolic pathway analysis showed that histidine metabolism, D-glutamine and D-glutamate metabolism, biotin metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and alanine, aspartate and glutamate metabolism in B. dorsalis larvae are significantly relevant pathways affected by azadirachtin. Although extrapolating the bioactivity results in this study to the practical project of B. dorsalis pest management in the field has limitations, it was found that azadirachtin has a significant effect on the primary metabolism of B. dorsalis larvae.

[Dynamic Posturography of Injured Lower Limb in Postural Evoked Response].

OBJECTIVE: To analyze the balance function of injured lower limb by dynamic posturography. METHODS: Using the dynamic posturography instrument, the postural evoked responses of sixty-two normal people and two hundred and fifty-eight people with injured lower limb bones and joints were detected. The test was included sensory organization test (SOT) and adaption test (ADT). The results of two groups were compared by t test. RESULTS: Compared with the normal people, the impaired people had significant statistical differences in balance scores of SOT3-SOT6 and proportion score of dynamic proprioception (P < 0.05). There was no obvious decrease in ADT. CONCLUSION: The balance function of injured lower limb significantly decreases.

[Posture evoked response detecting in normal lower limb muscle and its influencing factors].

OBJECTIVE: To analyze the latency of posture evoked response of normal lower limb muscle in different stimulations and explore its influencing factors. METHODS: The normal lower limb was induced to produce postural evoked response by the dynamic posturography through two kinds of perturbations, the supporting surface rotation stimulation (Toes-up and Toes-down) and the horizontal perturbation stimulation (Forward and Backward). The latencies of tibialis anterior muscle and gastrocnemius muscle were recorded by surface electromyography acquisition system. The differences of the left and right limb, gender and height on the latency of postural evoked response were analyzed. RESULTS: (1) Under the Toes-up and Backward perturbation, the latency of tibialis anterior muscle was longer than gastrocnemius muscle; under the Toes-down and Forward perturbation, the latency of gastrocnemius muscle was longer than tibialis anterior muscle. (2) The latencies of left limb and right limb had no significant difference. (3) The latency in male was longer than that in female. (4) The latency gradually increased with the increase of height. CONCLUSION: In the postural evoked response, different perturbations, gender and height have significant impacts on the latency of posture evoked response of lower limb muscle. However, the effect of height and gender should be not considered referring to the same individual.