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首页> 外文期刊>Journal of Plant Physiology >IMPACTS OF ULTRAVIOLET-B IRRADIATION ON NITROGEN-FIXING CYANOBACTERIA OF RICE PADDY FIELDS
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IMPACTS OF ULTRAVIOLET-B IRRADIATION ON NITROGEN-FIXING CYANOBACTERIA OF RICE PADDY FIELDS

机译：紫外线B辐射对水稻田固氮蓝细菌的影响。

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摘要

The impact of ultraviolet-B (UV-B; 280-315 nm) irradiation on ribulose 1,5-bisphosphate carboxylase (RuBISCO) activity membrane permeability, (NaHCO3)-C-14 uptake and isolated phycocyanin has been studied in five Nz-fixing cyanobacterial strains, viz., Anabaena sp., Nestoc sp., Nestoc carmium, Nestoc commune and Scytonema sp., isolated from Indian rice paddy fields. UV-B exposure for as little as 30 min resulted in a considerable decrease in the RuBISCO activity which further decreased with increasing exposure time. Similarly, (NaHCO3)-C-14 uptake was also severely affected by UV-B irradiation in all cyanobacterial strains studied so far. Isolated phycocyanin (lambda(max) 620 nm) of Anabaena sp. showed a drastic decline in absorbance with increasing exposure time. Fluorescence excitation at 620 nm resulted in an emission at 640 nm that decreased as well and showed a gradual shift towards shorter wavelengths with increasing UV-B exposure time, indicating an impaired energy transfer from the accessory pigment, phycocyanin, to the photosynthetic reaction centers. SDS-PAGE analyses of the isolated phycocyanin revealed a loss in the alpha beta monomers (20 kDa), the rod-core linker polypeptides (45 kDa) and the core-membrane linker polypeptides (70 kDa), denoting a disintegration of the aggregation state of phycocyanin following UV-B exposure and thus the uncoupling of the energy transfer pathway. Cyanobacterial membrane disruption occurs during UV-B irradiation, leading to changes in membrane permeability and release of C-14 labelled compounds.
机译：在五个Nz--N-中研究了UV-B（UV-B; 280-315 nm）辐射对核糖1,5-双磷酸羧化酶（RuBISCO）活性膜通透性，（NaHCO3）-C-14摄取和分离的藻蓝蛋白的影响。从印度稻田中分离出的固定蓝细菌菌株，即Anabaena sp。，Nestoc sp。，Nestoc carmium，Nestoc commune和Scytonema sp.。短短30分钟的UV-B暴露导致RuBISCO活性大大降低，并随着暴露时间的增加而进一步降低。同样，到目前为止，研究的所有蓝细菌菌株中，（NaHCO3）-C-14的摄取也受到UV-B辐射的严重影响。分离的藻蓝藻藻蓝蛋白（λ（最大）620 nm）。随着暴露时间的增加，吸光度急剧下降。 620 nm处的荧光激发导致640 nm处的发射也减少，并且随着UV-B暴露时间的增加而逐渐向较短波长移动，这表明从辅助颜料藻蓝蛋白到光合作用反应中心的能量转移受到损害。对分离的藻蓝蛋白的SDS-PAGE分析显示，αβ单体（20 kDa），杆-核心接头多肽（45 kDa）和核心-膜接头多肽（70 kDa）丢失，表明聚集状态的解体紫外线-B照射后藻蓝蛋白的释放，从而使能量传递途径解偶联。蓝细菌膜破坏发生在UV-B辐射期间，导致膜渗透性变化和C-14标记化合物的释放。

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