The interaction between legumes and rhizobia leads to the establishment of a beneficial symbiotic relationship. Recent advances in legume - rhizobium symbiosis revealed that various reactive oxygen and nitrogen species including nitric oxide (NO) play important roles during this process. Nodule development occurs with a transition from a normoxic environment during the establishment of symbiosis to a microoxic environment in functional nodules. Such oxygen dynamics are required for activation and repression of various NO production and scavenging pathways. Both the plant and bacterial partners participate in the synthesis and degradation of NO. However, the pathways of NO production and degradation as well as their cross-talk and involvement in the metabolism are still a matter of debate. The plant-originated reductive pathways are known to contribute to the NO production in nodules under hypoxic conditions. Non-symbiotic hemoglobin (phytoglobin) (Pgb) possesses high NO oxygenation capacity, buffers and scavenges NO. Its operation, through a respiratory cycle called Pgb-NO cycle, leads to the maintenance of redox and energy balance in nodules. The role of Pgb/NO cycle under fluctuating NO production from soil needs further investigation for complete understanding of NO regulatory mechanism governing nodule development to attain optimal food security under changing environment.

Plant mitochondria possess two different pathways for electron transport from ubiquinol: the cytochrome pathway and the alternative oxidase (AOX) pathway. The AOX pathway plays an important role in stress tolerance and is induced by various metabolites and signals. Previously, several lines of evidence indicated that the AOX pathway prevents overproduction of superoxide and other reactive oxygen species. More recent evidence suggests that AOX also plays a role in regulation of nitric oxide (NO) production and signalling. The AOX pathway is induced under low phosphate, hypoxia, pathogen infections, and elicitor treatments. The induction of AOX under aerobic conditions in response to various stresses can reduce electron transfer through complexes III and IV and thus prevents the leakage of electrons to nitrite and the subsequent accumulation of NO. Excess NO under various stresses can inhibit complex IV; thus, the AOX pathway minimizes nitrite-dependent NO synthesis that would arise from enhanced electron leakage in the cytochrome pathway. By preventing NO generation, AOX can reduce peroxynitrite formation and tyrosine nitration. In contrast to its function under normoxia, AOX has a specific role under hypoxia, where AOX can facilitate nitrite-dependent NO production. This reaction drives the phytoglobin–NO cycle to increase energy efficiency under hypoxia.

Background: Significant limb length discrepancy (LLD) after total hip arthroplasty (THA) is associated with limb, unremitting pain, neurological complications, and recurrent dislocations and has been a major cause of patient dissatisfaction and litigation against operating surgeon. The authors present a prospective study involving a double-stitch technique to prevent postoperative LLD after THA. Materials and Methods: Fifty patients undergoing primary THA over a period of 2 years were included in the study and were divided into two groups of 25 each. In Group I, double-stitch technique was used for intraoperative adjustment of preoperative radiological LLD, whereas in Group II, palpation and comparison of level of patella was used for assessment of LLD. Postoperative LLD and hip outcome scores were obtained and compared. Results: Postoperative radiological LLD (mean ± standard deviation) was 2.72 ± 2.07 mm (range −5 mm to +6 mm) in Group I and +4.28 ± 7.2 mm (range −15 mm to +12 mm) in Group II. Nine patients in Group I and 2 patients in Group II had no true clinical leg lengths discrepancy postoperatively. Postoperative radiological LLD within 5 mm could be achieved in 24 patients in Group I and in 9 patients in Group II. Conclusion: The study indicates that double-stitch technique is a simple and effective method in reducing postoperative LLD following THA.

An important and interesting feature of rice is that it can germinate under anoxic conditions. Though several biochemical adaptive mechanisms play an important role in the anaerobic germination of rice but the role of phytoglobin‐nitric oxide cycle and alternative oxidase pathway is not known, therefore in this study we investigated the role of these pathways in anaerobic germination. Under anoxic conditions, deepwater rice germinated much higher and rapidly than aerobic condition and the anaerobic germination and growth were much higher in the presence of nitrite. The addition of nitrite stimulated NR activity and NO production. Important components of phytoglobin‐NO cycle such as methaemoglobin reductase activity, expression of Phytoglobin1, NIA1 were elevated under anaerobic conditions in the presence of nitrite. The operation of phytoglobin‐NO cycle also enhanced anaerobic ATP generation, LDH, ADH activities and in parallel ethylene levels were also enhanced. Interestingly nitrite suppressed the ROS production and lipid peroxidation. The reduction of ROS was accompanied by enhanced expression of mitochondrial alternative oxidase protein and its capacity. Application of AOX inhibitor SHAM inhibited the anoxic growth mediated by nitrite. In addition, nitrite improved the submergence tolerance of seedlings. Our study revealed that nitrite driven phytoglobin‐NO cycle and AOX are crucial players in anaerobic germination and growth of deepwater rice.

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