King B J, Hunt S, Weagle G E, Walsh K B, Pottier R H, Canvin D T, Layzell D B
Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Plant Physiol. 1988 Jun;87(2):296-9. doi: 10.1104/pp.87.2.296.
A fiber optic spectrophotometric system was used to monitor the in vivo oxygenation of leghemoglobin in intact, attached soybean root nodules (Glycine max L. Merr. x USDA 16 Bradyrhizobium japonicum) which were flattened during development by growth in narrow, glass-walled cuvettes. When equilibrated at an external pO(2) of 20 kilopascals, leghemoglobin was 36.6 +/- 5.4% oxygenated, a value estimated to represent an infected cell O(2) concentration of 21.5 nanomolar. Increasing the external pO(2) from 20 to 25 kilopascals caused a rapid increase in leghemoglobin oxygenation, followed by a recovery to the initial level, all within 7.5 minutes. At 25 kilopascals O(2), the rates of H(2) and CO(2) evolution were similar to those at 20 kilopascals. Since respiration had not increased, the results support the proposal that nodules adapt to increased external pO(2) by regulating their resistance to O(2) diffusion.
使用光纤分光光度系统监测完整、附着的大豆根瘤（大豆品种Glycine max L. Merr. x USDA 16与日本慢生根瘤菌）中豆血红蛋白的体内氧合情况，这些根瘤在发育过程中因生长在狭窄的玻璃壁比色皿中而变平。当在20千帕的外部pO₂下平衡时，豆血红蛋白的氧合率为36.6±5.4%，该值估计代表感染细胞中21.5纳摩尔的O₂浓度。将外部pO₂从20千帕提高到25千帕会导致豆血红蛋白氧合迅速增加，随后恢复到初始水平，整个过程在7.5分钟内完成。在25千帕的O₂条件下，H₂和CO₂的释放速率与20千帕时相似。由于呼吸作用没有增加，结果支持了根瘤通过调节其对O₂扩散的阻力来适应外部pO₂增加的提议。
