本文選題：銨態(tài)氮 + 綠狐尾藻��； 參考：《鄭州大學(xué)》2017年碩士論文

【摘要】：富營養(yǎng)化現(xiàn)象會(huì)產(chǎn)生很多不利于沉水植物生長的因素,而水體中銨態(tài)氮濃度的升高是沉水植物在富營養(yǎng)化湖泊中消亡的重要因素這一觀點(diǎn)已成為共識(shí)。目前,國內(nèi)外關(guān)于水體中銨態(tài)氮對(duì)沉水植物的毒性效應(yīng)的研究主要集中于對(duì)銨態(tài)氮耐受度較低的沉水植物。本課題通過構(gòu)建微型環(huán)境,對(duì)三種沉水植物在銨態(tài)氮脅迫下的生理響應(yīng)進(jìn)行了對(duì)比研究;然后以耐受物種綠狐尾藻為主要研究對(duì)象,考察綠狐尾藻在高濃度銨態(tài)氮脅迫下的毒性效應(yīng)和過氧化損傷,分析各組織的毒性閾值;最后對(duì)綠狐尾藻在不同程度的銨態(tài)氮脅迫下的氮素代謝和調(diào)節(jié)酶活性差異進(jìn)行研究,探討耐受度較高的沉水植物在應(yīng)對(duì)高濃度銨態(tài)氮脅迫時(shí)的解毒機(jī)制,幫助我們認(rèn)識(shí)沉水植被在富營養(yǎng)化湖泊中的衰退機(jī)理以及恢復(fù)重建工作。試驗(yàn)結(jié)果表明:1.常見沉水植物如金魚藻和狐尾藻在10 mg L-1銨態(tài)氮濃度下就會(huì)表現(xiàn)出生物量負(fù)增長和葉綠素水平顯著降低的現(xiàn)象,而綠狐尾藻的相對(duì)生長速率和葉綠素含量隨著銨態(tài)氮濃度從1到20 mg L-1的增長而增長。銨態(tài)氮的過量蓄積所產(chǎn)生的毒性效應(yīng)往往導(dǎo)致沉水植物體內(nèi)可溶性蛋白質(zhì)和非結(jié)構(gòu)性碳水化合物含量的下降,而綠狐尾藻對(duì)于銨態(tài)氮的高耐受度主要由于對(duì)C-N代謝的調(diào)節(jié)管制,這種調(diào)節(jié)管制有效避免了過量銨態(tài)氮可能造成的毒性損傷。2.綠狐尾藻在80 mg L-1的銨態(tài)氮濃度下出現(xiàn)生長速率下降和葉綠素含量降低,膜脂過氧化水平增長的現(xiàn)象。當(dāng)銨態(tài)氮濃度升至120 mg L-1時(shí),綠狐尾藻的生物量在實(shí)驗(yàn)后期出現(xiàn)負(fù)增長,根系組織開始表現(xiàn)損傷,抗氧化系統(tǒng)損傷加劇。綠狐尾藻的根系組織對(duì)銨態(tài)氮的耐受程度高于葉片組織,但在120 mg L-1的銨態(tài)氮濃度下根系組織也表現(xiàn)出顯著的毒性效應(yīng)。3.作為對(duì)銨態(tài)氮耐受程度較高的沉水植物,綠狐尾藻可以高效地利用氮素,這與綠狐尾藻體內(nèi)氮素代謝的關(guān)鍵酶類密切相關(guān)。綠狐尾藻對(duì)于銨態(tài)氮的解毒恢復(fù)和應(yīng)對(duì)氮素缺乏的代謝調(diào)節(jié)分別與其體內(nèi)天冬酰胺酶和硝酸還原酶的高效表達(dá)密切相關(guān)。銨態(tài)氮濃度的增加對(duì)于綠狐尾藻組織內(nèi)的氮素調(diào)節(jié)酶類有顯著影響,當(dāng)銨態(tài)氮濃度達(dá)到120 mg L-1時(shí),隨著實(shí)驗(yàn)的進(jìn)行,綠狐尾藻的谷氨酰胺合成酶和天冬酰胺酶的活性顯著下降。綠狐尾藻可以通過有效的代謝調(diào)節(jié)實(shí)現(xiàn)對(duì)于銨態(tài)氮的解毒,這與敏感物種的代謝機(jī)制有很大差別,而調(diào)節(jié)綠狐尾藻氮代謝的關(guān)鍵酶類在組織間表現(xiàn)出明顯差異。
[Abstract]:The phenomenon of eutrophication will produce many unfavorable factors to the growth of submerged plants, and the increasing of ammonium nitrogen concentration in water is an important factor for the extinction of submerged plants in eutrophic lakes. At present, the toxicity of ammonium nitrogen to submerged plants is mainly focused on submerged plants with low tolerance to ammonium nitrogen. In this study, the physiological responses of three submerged plants under ammonium nitrogen stress were studied by constructing microenvironment, and then the tolerant species green foxtail algae was taken as the main research object. The toxic effects and peroxidation damage of P. virulent under high concentration of ammonium nitrogen stress were investigated, and the toxicity threshold of each tissue was analyzed. Finally, the difference of nitrogen metabolism and regulatory enzyme activity in different levels of ammonium nitrogen stress was studied. The detoxification mechanism of submerged plants with high tolerance to high concentration of ammonium nitrogen was discussed, which helps us to understand the decline mechanism of submerged vegetation in eutrophic lakes and the restoration and reconstruction of submerged vegetation. The test results show that 1: 1. Common submerged plants such as goldfish and foxtail showed negative biomass growth and significant decrease in chlorophyll level at the concentration of 10 mg L-1 ammonium nitrogen. The relative growth rate and chlorophyll content increased with the increase of ammonium nitrogen concentration from 1 to 20 mg L ~ (-1). The toxic effect of excessive accumulation of ammonium nitrogen often leads to the decrease of soluble protein and non-structural carbohydrate content in submerged plants, while the high tolerance to ammonium nitrogen is mainly due to the regulation of C-N metabolism. This regulatory regulation effectively avoids the toxic damage. 2. 2 that may be caused by excessive ammonium nitrogen. The growth rate and chlorophyll content decreased and the membrane lipid peroxidation level increased at the concentration of 80 mg 路L ~ (-1) ammonium nitrogen. When the concentration of ammonium nitrogen increased to 120 mg / L, the biomass of Phaeophyllum sp. increased negatively, the root tissue began to show damage, and the damage of antioxidant system was aggravated. The tolerance of root tissue to ammonium nitrogen was higher than that of leaf tissue, but the root tissue also showed significant toxicity at 120 mg 路L ~ (-1) of ammonium nitrogen. As a submerged plant with high tolerance to ammonium nitrogen, the algae can utilize nitrogen efficiently, which is closely related to the key enzymes of nitrogen metabolism. The detoxification of ammonium nitrogen and the metabolic regulation of nitrogen deficiency were closely related to the high expression of asparaginase and nitrate reductase respectively. When the concentration of ammonium nitrogen reached 120 mg 路L ~ (-1), the activities of glutamine synthetase and asparaginase decreased significantly. The detoxification of ammonium nitrogen can be achieved by effective metabolic regulation, which is very different from the metabolic mechanism of sensitive species, and the key enzymes regulating the nitrogen metabolism of green fox tail algae show significant differences among tissues.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X173;X52

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本文編號(hào)：2031974