Wounding induces a peroxisomal H2 O2 decrease via glycolate oxidase-catalase switch dependent on glutamate receptor-like channel-supported Ca2+ signaling in plants.

Sensing of environmental challenges, such as mechanical injury, by a single plant tissue results in the activation of systemic signaling, which attunes the plant's physiology and morphology for better survival and reproduction. As key signals, both calcium ions (Ca2+ ) and hydrogen peroxide (H2 O2 ) interplay with each other to mediate plant systemic signaling. However, the mechanisms underlying Ca2+ -H2 O2 crosstalk are not fully revealed. Our previous study showed that the interaction between glycolate oxidase and catalase, key enzymes of photorespiration, serves as a molecular switch (GC switch) to dynamically modulate photorespiratory H2 O2 fluctuations via metabolic channeling. In this study, we further demonstrate that local wounding induces a rapid shift of the GC switch to a more interactive state in systemic leaves, resulting in a sharp decrease in peroxisomal H2 O2 levels, in contrast to a simultaneous outburst of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived apoplastic H2 O2 . Moreover, the systemic response of the two processes depends on the transmission of Ca2+ signaling, mediated by glutamate-receptor-like Ca2+ channels 3.3 and 3.6. Mechanistically, by direct binding and/or indirect mediation by some potential biochemical sensors, peroxisomal Ca2+ regulates the GC switch states in situ, leading to changes in H2 O2 levels. Our findings provide new insights into the functions of photorespiratory H2 O2 in plant systemic acclimation and an optimized systemic H2 O2 signaling via spatiotemporal interplay between the GC switch and NADPH oxidases.

Dynamic and fluctuating generation of hydrogen peroxide via photorespiratory metabolic channeling in plants.

The homeostasis of hydrogen peroxide (H2 O2 ), a key regulator of basic biological processes, is a result of the cooperation between its generation and scavenging. However, the mechanistic basis of this balance is not fully understood. We previously proposed that the interaction between glycolate oxidase (GLO) and catalase (CAT) may serve as a molecular switch that modulates H2 O2 levels in plants. In this study, we demonstrate that the GLO-CAT complex in plants exists in different states, which are dynamically interchangeable in response to various stimuli, typically salicylic acid (SA), at the whole-plant level. More crucially, changes in the state of the complex were found to be closely linked to peroxisomal H2 O2 fluctuations, which were independent of the membrane-associated NADPH oxidase. Furthermore, evidence suggested that H2 O2 channeling occurred even in vitro when GLO and CAT worked cooperatively. These results demonstrate that dynamic changes in H2 O2 levels are physically created via photorespiratory metabolic channeling in plants, and that such H2 O2 fluctuations may serve as signals that are mechanistically involved in the known functions of photorespiratory H2 O2 . In addition, our study also revealed a new way for SA to communicate with H2 O2 in plants.

Right gasless transaxillary endoscopic total thyroidectomy (RGTETT) with video: our experience with the posterior approach: Lei's seven-sinking method.

Our video demonstrates a modified gasless transaxillary endoscopic thyroid surgery with the posterior approach for bilateral low-risk thyroid cancer. In this paper, we provided a detailed introduction to the right gasless transaxillary endoscopic total thyroidectomy surgical procedure for bilateral low-risk thyroid cancer, and briefly summarized the Lei's seven-sinking method: sinking the clavicular head of the sternocleidomastoid muscle (CHSCM); sinking the cervical vascular sheath; sinking the right wall of the esophagus; sinking the right recurrent laryngeal nerve (RLN); sinking the trachea; sinking the left RLN and sinking the thyroid. A 5-cm incision was made starting from the anterior axillary line along the natural fold at the axilla. A trocar was placed in the axillary incision approximately 3-5 cm away from the side of the breast and slightly below the anterior axillary line. Using blunt dissection and electrocautery, a working space was created by elevating a subcutaneous flap above the pectoralis major muscle. The thyroid bed was accessed through the two heads of the SCM, and then the thyroid was separated from the strap muscles. Thyroidectomy and central lymph node dissection were fully endoscopically performed with the posterior approach using conventional endoscopic instruments. Through the posterior approach and the operation steps of the seven-sinking method, total thyroidectomy and bilateral central lymph node dissection can be achieved relatively easily.