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The inhibitory mechanism of ammonium on the photosynthesis of rice-field cyanobacterium GE-XIAN-MI (Nostoc) Guozheng Dai 1 , Charles P. Deblois 2 , Shuwen Liu 1 , Philippe Juneau 3 Baosheng Qiu 1, * 1 College of Life Sciences, Central China Normal University, Wuhan 430079, Hubei, P. R. China; 2 Départment des Sciences Biologiques - TOXEN, Canada Research Chair on Ecotoxicology of Aquatic Microorganisms, Université du Québec à Montréal, Succursale Centre-ville, C.P. 8888 Montréal, Québec, Canada H3C 3P8; * Author for correspondence. Intensive agricultural activities lead to an increase reduced nitrogen concentration in the atmosphere. It is estimated that nitrogen deposition from the atmosphere (NH 3 ) linked to human activities can reach level as high as 50 kg·ha -1·yr -1 in some parts of Europe. This additional + nitrogen input has led to the nitrogen saturation of many natural ecosystems. Because NH 4 assimilation requires less energy than NO - 3 , it is usually expected to be preferred by plants. However, the ammonium ion is notorious for its toxic effects on many, if not all, plant strains, only a few strains perform well when NH + 4 is the only, or predominant, nitrogen source. Although the toxicity of ammonium has been observed for more than one hundred years, most reports concentrated on the study of animal, higher plant, phytoplankton, bacterium, and yeast, and relatively less attention has been paid to cyanobacteria. The edible cyanobacterium Ge-Xian-Mi (Nostoc sp.) grows in some mountain paddy fields in China during winter. Domesticated rice species are highly adapted to NH + 4 as the nitrogen source and can tolerate up to 10 mmol·L -1 NH + 4 . In order to enhance crop yield, local people usually use high concentrations of nitrogen fertilizers in paddy fields. Thus, NH + 4 concentrations can reach high levels in these fields and may be toxic to the growth of Nostoc sp. (Ge-Xian-Mi). However, no experimental evidence has been published on whether these fertilizers may cause reduction of Ge-Xian-Mi or other Nostoc species productivity. In this work, effects of two fertilizers, NH 4 Cl and KCl, on the growth of the edible cyanobacterium Ge-Xian-Mi (Nostoc) and other four cyanobacterial strains were compared at pH 8.3±0.2 and 25 °C. Their growth was decreased by at least 65% at 10 mmol·L -1 NH 4 Cl but no inhibitory effect was observed at the same level of KCl. Meanwhile, they exhibited a great variation of sensitivity to NH + 4 toxicity in the order: Ge-Xian-Mi > Anabaena azotica FACHB 118 > Microcystis aeruginosa FACHB 905 > Microcystis aeruginosa FACHB 315 > Synechococcus FACHB 805. The relative growth rate 96-h EC 50 value of NH + 4 for Ge-Xian-Mi was 1.105 mmol·L -1 , which was much less than NH + 4 concentration in many agricultural soils (2 to 20 mmol·L -1 ). These indicated that the use of ammonium as nitrogen fertilizer was responsible for the reduced resource of Ge-Xian-Mi in the paddy field. After 96 h exposure to 1 mmol·L -1 NH 4 Cl, the photosynthetic rate, F v /F m value, saturating irradiance for photosynthesis and PSII activity of Ge-Xian-Mi colonies were remarkably decreased. The chlorophyll synthesis of Ge-Xian-Mi was more sensitive to NH + 4 toxicity than phycobiliproteins. Thus, its functional absorption cross section of PSII was increased markedly at NH 4 Cl levels ≥ 1 mmol·L -1 and the electron transport on the acceptor side of PSII was significantly accelerated by NH 4 Cl addition ≥ 3 mmol·L -1 . Dark respiration of Ge-Xian-Mi was significantly increased by 246% and 384% at 5 and 10 mmol·L -1 NH 4 Cl respectively. The rapid fluorescence rise kinetic indicated that the oxygen-evolving complex of PSII was the inhibitory site of NH + 4 . Keywords:Cyanobacterium GE-XIAN-MI (Nostoc); ammonium; photosynthesis; rice-field www.cspp.cn & 87
Comparison of Photosynthetic Parameters of Sexually Different Parts of Porphyra katadai var. hemiphylla (Bangiales, Rhodophyta) during Dehydration and Rehydration Apeng Lin, Guangce Wang, Fang Yang, Guanghua Pan, Baicheng Zhou Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China Physiological data from extreme habitat organisms during these stresses are vital information for comprehending their survival. Intertidal seaweeds are exposed to a combination of environmental stresses. In this work the photosynthetic performance of both PS Ⅰ and PS Ⅱ of P. katadai var. hemiphylla during dehydration and re-hydration were investigated by Dual-PAM-100 fluorometer. The photosynthetic parameters showed similar pattern under low-grade dehydration. However, when the absolute water content reached 42%, PS Ⅰ of the female parts were nearly shut down and while the PS Ⅰ of the male parts still well coordinated and working properly with PS Ⅱ. As after re-hydration, within an hour, the male part can restore photosynthesis while the female parts can not and it is shown that under severe dehydration, PS Ⅰ is more unstable than PS Ⅱ, thus, in P. katadai, the susceptibility of photosynthesis to dehydration depends on the accommodative ability of PS Ⅰ under severe dehydration. Keywords: Porphyra katadai var. hemiphylla; desiccation-tolerant; chlorophyll fluorescence; P700 + absorbance; effective quantum yield; electron transport rate www.cspp.cn 88
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目录目录 ( I) 专题一 :
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新疆塔里木河下游刚
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殷宏章先生 (1908.10.1—19
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1908 年 :10 月 1 日出生于
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一、研究论文殷宏章
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4. 殷宏章等译 . 勒克
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香港。在船上航行数
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怀念殷宏章先生诞生
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光情况、生物量 ( 有
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环境条件。1980 年他在
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追思殷宏章先生对青
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饮水思源师恩难忘 —
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追忆先贤殷宏章先生
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在文汇报上。2) 在殷
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Page 44 and 45: Investigations of photosynthetic el
Page 46 and 47: 单双子叶植物光系统
Page 48 and 49: 蓝藻和红藻光合作用
Page 50 and 51: 瞬时脉冲光调控脱黄
Page 52 and 53: 低浓度 NaHSO 3 促进非依
Page 54 and 55: 蓝藻状态转换机制的
Page 56 and 57: 水稻中脉白色突变体
Page 58 and 59: 拟南芥花叶突变体 thf
Page 60 and 61: Defect in Degradation of PSII Compl
Page 62 and 63: Rubisco 体外重组中分子
Page 64 and 65: 蓝藻 CCM 的无机碳转运
Page 66 and 67: 盐胁迫对蓝藻光系统
Page 68 and 69: 应用叶绿素荧光成像
Page 70 and 71: 关于净光合速率和胞
Page 72 and 73: 不同天气条件下银杏
Page 74 and 75: 新疆塔里木河下游刚
Page 76 and 77: 小麦幼苗对连续强光
Page 78 and 79: 不同光质对茄子叶片
Page 80 and 81: 耐荫植物不同强光胁
Page 82 and 83: 温度胁迫对苜蓿和柱
Page 84 and 85: 不同季节水蜜桃光合
Page 86 and 87: 高锰胁迫下空心莲子
Page 88 and 89: 水稻 ADC1 基因的克隆
Page 90 and 91: Impacts of increased atmospheric CO
Page 94 and 95: Systems Biology of Photosynthesis (
Page 96 and 97: Comparison of model describing ligh
Page 98 and 99: 干热河谷木本植物光
Page 100 and 101: 水分胁迫下 ABA 诱导 H 2
Page 102 and 103: 不同类型专用小麦非
Page 104 and 105: 小麦双增剂增产的光
Page 106 and 107: N 亏缺对灌浆期玉米
Page 108 and 109: 木薯叶片光合特性研
Page 110 and 111: 暖温带落叶阔叶林土
Page 112 and 113: 鸢尾叶片取向与其光
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