本文選題：納米銀　切入點：銀離子　出處：《華南農(nóng)業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：納米銀(AgNPs)是目前國內(nèi)外生產(chǎn)和使用量最大的納米材料之一,由于AgNPs具有多種優(yōu)越的性能,被廣泛應(yīng)用于工業(yè)生產(chǎn)、醫(yī)療衛(wèi)生和環(huán)境保護等領(lǐng)域。AgNPs可能在產(chǎn)品生產(chǎn)、使用和回收等環(huán)節(jié)中通過多種途徑進入到水體環(huán)境中,對水生生態(tài)系統(tǒng)中的非靶標(biāo)生物造成潛在威脅。關(guān)于AgNPs對一些微藻和微型水生動物的毒性已經(jīng)有很多的報道,但是關(guān)于AgNPs對具有重要生態(tài)功能的絲狀固氮藍藻影響的研究鮮有報道。同時,關(guān)于AgNPs對微型藻類的毒性效應(yīng)機理存在爭議。因此,本論文選用念珠藻(Nostoc sp.)為實驗材料,研究用檸檬酸鈉還原法制備的AgNPs和銀離子(Ag+)對念珠藻的急性和亞急性毒性效應(yīng),試圖從藻形態(tài)結(jié)構(gòu)、生理、生化改變等角度揭示AgNPs對絲狀固氮藍藻-念珠藻的致毒機理。主要研究結(jié)果如下:急性毒性實驗(4d)中,在0~48h內(nèi),AgNPs和Ag+處理后,培養(yǎng)液中溶解態(tài)銀濃度均逐漸下降并趨于平衡。AgNPs處理的小顆粒銀濃度在0~6h內(nèi)急劇下降,但在24h后趨于穩(wěn)定。Ag+處理的小顆粒銀濃度在0~12h內(nèi)幾乎沒有變化,但到12h后顯著升高到24h達到最高。顯微觀察發(fā)現(xiàn)高濃度的AgNPs和Ag+均可引起細胞收縮、質(zhì)壁分離、胞內(nèi)物質(zhì)紊亂和細胞壁裂解等現(xiàn)象,AgNPs處理后疑似有銀顆粒進入了細胞內(nèi)部。所有濃度AgNPs和Ag+處理4d后的念珠藻干重、Chla含量、藻體TC含量、藻體碳/氮比和固氮酶活性均顯著低于CK,而藻體總氮含量(TN)均顯著高于對照。AgNPs處理后,培養(yǎng)液中碳/氮比均顯著高于CK,而0.04 mg·L-1 Ag+處理組碳氮比(C/N)低于CK,但0.06 mg·L-1 Ag+處理則與CK比無顯著差異。Ag+處理4d后,藻葉綠素?zé)晒鈪?shù)值Fm、Fv/Fm、Ψ0、ΦE0和PIABS均顯著低于CK,而ΦD0、ABS/RC、TR0/RC和DI0/RC均顯著高于CK,特別是ABS/RC和DI0/RC增加了97%和126%。但0.6mg·L-1AgNPs處理僅F0、Fm和ΦD0顯著降低,而Fv/Fm、Ψ0、ΦE0和PIABS顯著升高。同時,0.4 mg·L-1AgNPs處理所有參數(shù)均與CK無顯著差異。說明短期作用后,Ag+和AgNPs均對藻產(chǎn)生脅迫作用,但AgNPs對藻光合系統(tǒng)II的影響比Ag+小。亞急性毒性實驗(9d)中,僅高濃度AgNPs和Ag+處理使念珠藻干重和Chla含量顯著低于CK。Ag+處理均使藻體C/N顯著降低,但AgNPs處理無影響。0.6mg·L-1AgNPs處理使培養(yǎng)液中C/N、藻體可溶性蛋白和藻膽蛋白含量顯著高于CK,其余處理組無顯著變化。Ag+顯著降低念珠藻固氮酶活性,AgNPs則對固氮酶活性無顯著影響。處理9d后藻細胞蛋白二維電泳記錄到超過200個差異蛋白點,選擇與CK表達差異超過2.5倍以上的132個點進行了蛋白定性,只匹配到51蛋白質(zhì),扣除12個重復(fù)的蛋白,總共定性差異蛋白39個。當(dāng)0.06 mg·L-1 Ag+處理后,藻細胞中26個蛋白顯著上調(diào),但6種蛋白的表達下調(diào),而0.6 mg·L-1 AgNPs處理時,22個蛋白顯著上調(diào),3個顯著下調(diào)。對兩種形態(tài)銀處理,上調(diào)蛋白中有相同蛋白10個,下調(diào)蛋白中有1個相同,但唯有一種在光合作用的卡爾文循環(huán)中起關(guān)鍵作用蛋白-轉(zhuǎn)酮醇酶在AgNPs處理時顯著上調(diào),Ag+處理時顯著下調(diào)。同時,Ag+處理抑制固氮酶表達,但AgNPs處理沒有變化,這與前述乙炔還原法測定到固氮酶活性結(jié)果一致。AgNPs處理時別藻藍蛋白上調(diào),但Ag+處理未發(fā)現(xiàn)變化,這與光度法測得結(jié)果一致。另外,Ag+使微藻抗氧化的重要酶類-超氧化物歧化酶上調(diào),但是AgNPs處理沒有這種變化。Ag+處理9d后,藻葉綠素?zé)晒鈪?shù)值F0、Fm、Fv/Fm、Ψ0、ΦE0、PIABS和ET0/RC均顯著高于對照,但ΦD0、VJ、ABS/RC、TR0/RC和DI0/RC值均顯著低于CK,特別是ABS/RC和DI0/RC兩個參數(shù)值分別降低超過70%。但對于AgNPs,僅0.4 mg·L-1和0.6 mg·L-1處理F0值和0.6 mg·L-1處理Fm值顯著高于CK以外,其他參數(shù)均與CK無顯著差異。這與急性實驗的參數(shù)值變化趨勢幾乎完全相反。上述結(jié)果說明AgNPs和Ag+對念珠藻細胞光合作用、固氮作用、蛋白合成的影響存在明顯差異。另外,實驗結(jié)果表明隨AgNPs和Ag+濃度的增加,藻體銀含量增加,0.6 mg·L-1 AgNPs處理時藻到富集量最大,且同種處理方式下藻體銀含量在第9d的含量均低于第4d。結(jié)合上述生長和生理生化數(shù)據(jù),說明念珠藻在短期受到高濃度AgNPs和Ag+的毒害比較嚴重,但從處理9d后的生理生化指標(biāo)變化的結(jié)果來看,念珠藻對Ag+和AgNPs均產(chǎn)生了相當(dāng)程度的適應(yīng),但對兩種形態(tài)銀的適應(yīng)策略存在明顯差異。
[Abstract]:Silver nanoparticles (AgNPs) is one of the largest domestic production and consumption of nano materials, because AgNPs has many excellent properties, is widely used in industrial production, health and environmental protection in areas such as.AgNPs may in the production, use and recycling and other aspects through a variety of ways to enter the aquatic environment, causing potential the threat to the aquatic ecosystem in non target organisms. On the toxicity of AgNPs to some microalgae and micro aquatic animal that there have been many reports, but about AgNPs of filamentous cyanobacteria affect important ecological function has not been studied. At the same time, a toxic effect mechanism of AgNPs on micro algae is controversial. Therefore, this thesis selection of Nostoc (Nostoc sp.) as experimental materials, research using sodium citrate reduction method to prepare AgNPs and silver ion (Ag+) on acute and subacute toxicity effect of Nostoc Should try to from the algae morphology, physiological, biochemical changes of filamentous cyanobacteria reveal AgNPs - Nostoc toxicity mechanism. The main results are as follows: acute toxicity test (4D), in 0~48h, AgNPs and Ag+ after treatment, the concentration of dissolved silver culture was gradually decreased and tended to be small particles of silver concentration decreased sharply in balance with.AgNPs 0~6h, but in 24h tends to small Ag concentration and stable.Ag+ treatment in 0~12h almost no change, but 12h increased significantly to the highest 24h. Microscopic observation results showed that high concentration of AgNPs and Ag+ could induce cell contraction, plasmolysis, cell substances in disorder and cell wall cracking phenomenon, after AgNPs treatment of suspected silver particles into the interior of the cell. All the concentrations of AgNPs and Ag+ 4D after the treatment of Nostoc dry weight, Chla content, TC content of algae, algae carbon / nitrogen ratio and nitrogenase activity were significantly lower 浜嶤K,鑰岃椈浣撴，

本文編號：1594546