李嬌,王姮,韓昭衡,石生寶,王永華,丁君
大連海洋大學(xué) 農(nóng)業(yè)部海洋水產(chǎn)增養(yǎng)殖學(xué)與生物技術(shù)重點(diǎn)開放實(shí)驗(yàn)室,大連116023
8種常見農(nóng)藥對(duì)海膽胚胎各發(fā)育期的急性毒性
李嬌,王姮,韓昭衡,石生寶,王永華,丁君*
大連海洋大學(xué) 農(nóng)業(yè)部海洋水產(chǎn)增養(yǎng)殖學(xué)與生物技術(shù)重點(diǎn)開放實(shí)驗(yàn)室,大連116023
為初步探討農(nóng)藥對(duì)海膽胚胎的急性毒性效應(yīng),以蝦夷馬糞海膽(Strongylocentyotus internedius)為實(shí)驗(yàn)材料,研究了 8種常見農(nóng)藥——草甘膦(Glyphosate)、百草枯(Paraquat)、異菌脲(Iprodione)、代森錳鋅(Mancozeb)、三唑醇(Triadimenol)、霜霉威(Propamocarb)、百菌清(Chlorothalonil)和速克靈(Procymidone)對(duì)海膽胚胎各發(fā)育期(二細(xì)胞期、四細(xì)胞期、上浮囊胚期、原腸期、棱柱幼體期、四腕幼蟲期)的半數(shù)效應(yīng)濃度(EC50),并分析了正辛醇/水分配系數(shù)(LogP)與EC50的關(guān)系.結(jié)果顯示:1)8種農(nóng)藥對(duì)海膽胚胎各發(fā)育期均具有一定的急性毒性,以四腕幼蟲期為例,8種農(nóng)藥的EC50值分別為草甘膦(3.99mg·L-1)>百草枯(10.38mg·L-1)>代森錳鋅(20.77mg·L-1)>速克靈(55.42mg·L-1)>霜霉威(56.09mg·L-1)>異菌脲(86.29mg·L-1)>三唑醇(273.20mg·L-1)>百菌清(647.38mg·L-1).2)LogP與EC50呈現(xiàn)一定的正相關(guān)性,即隨著LogP的增加,各農(nóng)藥對(duì)海膽胚胎的抑制率逐漸降低.
農(nóng)藥;蝦夷馬糞海膽;胚胎發(fā)育;毒性影響
Received 10 December 2009 accepted 16 January 2010
Abstract:Toxic effects of commonly used eight pesticides(Glyphosate,Paraquat,Iprodione,Mancozeb,Triadimenol, Propamocarb,Daconil and Sumilex)on the embryo development of the sea urchin Strongylocentrotus intermedius were evaluated in this work.Toxicity was quantified in terms of the EC50(median effective concentration)on the six early developmental stages of sea urchin embryo(2-cell,4-cell,blastula,gastrula,prism,and 4-arm pluteus).Then the concentration—response curves for each pesticide and the relationship between octanol/water partition coefficient(logP)and EC50of each embryonic development stage were surveyed and analysed.Results showed that 1)all the eight pesticides had toxic effects on the whole embryo development,comparing the EC50values of each pescide at the 4-arm pluteus stage, they were ranked in decreasing order of toxicity EC50as follows:Glyphosate(3.99mg·L-1)>Paraquat(10.38mg·L-1)>Mancozeb(20.77mg·L-1)>Procymidone(55.42mg·L-1)>Propamocarb(56.09mg·L-1)>Iprodione(86.29mg·L-1)>Triadimenol(273.20mg·L-1)>Chlorothalonil(647.38mg·L-1).2)There was a positive correlation between the LogP and EC50of each stage,i.e.as the value of logP increasing,the inhibition rate of the pesticides on the embryos decreased.
Keywords:pesticide;Strongylocentyotus internedius;embryo development;toxicity
隨著工農(nóng)業(yè)生產(chǎn)的發(fā)展,近年來農(nóng)藥的用量不斷增加.農(nóng)藥在殺滅病蟲害、提高農(nóng)作物產(chǎn)量的同時(shí)也會(huì)造成嚴(yán)重的環(huán)境污染.研究表明,農(nóng)藥可直接或間接危害人類和其他生物健康,對(duì)生殖系統(tǒng)和胚胎發(fā)育具有顯著影響(Manzo et al.,2005).海洋處于地球的最低處,陸地上的各種污染物最終都將進(jìn)入海洋(劉維屏,2006).農(nóng)藥可通過河流、降水、地下水等多種途徑進(jìn)入海洋,進(jìn)而導(dǎo)致浮游動(dòng)、植物及其他水生生物生理、生態(tài)、品種和數(shù)量的變化,嚴(yán)重影響海洋生態(tài)系統(tǒng)的健康(岳文潔等,2009;何忠文等,2009).因此,研究農(nóng)藥對(duì)海洋生物的毒性作用具有重要意義.然而,與陸生生物相比,農(nóng)藥對(duì)海洋生物的毒性效應(yīng)研究尚較為缺乏(孫雪峰等,2009).
海膽屬于后口動(dòng)物,具有個(gè)體相對(duì)小、生命力強(qiáng)、適應(yīng)性廣、在實(shí)驗(yàn)室控制條件下容易飼養(yǎng)、繁殖周期相對(duì)短、能分批產(chǎn)卵或連續(xù)產(chǎn)卵、產(chǎn)卵量大等特點(diǎn),在海洋生物學(xué)實(shí)驗(yàn)中具有廣泛應(yīng)用,并已成為海洋生態(tài)毒理學(xué)研究的模式生物(Semenova et al.,2006;Berdyshev et al.,1995).胚胎期和幼蟲期是海膽生命中對(duì)污染物最敏感的時(shí)期,目前日本、加拿大和美國(guó)等國(guó)家已廣泛采用海膽胚胎和幼蟲來檢測(cè)重金屬的毒性和監(jiān)測(cè)海洋環(huán)境的污染狀況(His et al.,1999;Ringwood,1991;Carr et al., 1995;Beiras et al.,2003;Bellas et al.,2003;Bellas et al.,2005;Marc et al.,2002;Phillips et al.,2003; Hamdoun et al.,2002;Larrain et al.,1999;Woodworth et al.,1999;Kobayashi and Okamura,2005).然而以海膽胚胎和幼蟲為受試對(duì)象檢測(cè)常見農(nóng)藥的毒性尚不多見,國(guó)內(nèi)僅有孫雪峰等(2009)進(jìn)行了初步研究.本研究在此基礎(chǔ)上,以蝦夷馬糞海膽(Strongylocentyotus internedius)為實(shí)驗(yàn)材料,研究了8種農(nóng)藥對(duì)海膽胚胎的急性毒性,得到了8種農(nóng)藥對(duì)海膽胚胎各發(fā)育期的半數(shù)效應(yīng)濃度即EC50值,填補(bǔ)了常見農(nóng)藥對(duì)海膽胚胎急性毒性數(shù)據(jù)的空白,為深入研究農(nóng)藥對(duì)海洋生物的影響,制定完善的環(huán)境排放標(biāo)準(zhǔn)及風(fēng)險(xiǎn)管理提供了基礎(chǔ)毒理學(xué)依據(jù).
試驗(yàn)用蝦夷馬糞海膽(Strongylocentyotus internedius)取自大連水產(chǎn)學(xué)院重點(diǎn)實(shí)驗(yàn)室,殼徑3.6~4.8cm,殼高2.2~3.1cm.試驗(yàn)用海水取自大連黑石礁附近海域,經(jīng)過砂濾池過濾,鹽度32.2± 0.3,pH 8.13±0.5.
8種受試農(nóng)藥為草甘膦(Glyphosate)、百草枯(Paraquat)、異菌脲(Iprodione)、代森錳鋅(Mancozeb)、三唑醇(Triadimenol)、霜霉威(Propamocarb)、百菌清(Chlorothalonil)和速克靈(Procymidone),購(gòu)自中國(guó)藥品生物制品檢定所,均為標(biāo)準(zhǔn)品.
2.2.1 藥物濃度的設(shè)定
將農(nóng)藥溶于新鮮海水中配得母液,再由母液稀釋到實(shí)驗(yàn)所需濃度.先按照急性毒性試驗(yàn)方法進(jìn)行預(yù)試驗(yàn),確定海膽胚胎發(fā)育從受精到四腕幼蟲全死和不死的劑量范圍,根據(jù)預(yù)實(shí)驗(yàn)設(shè)定實(shí)驗(yàn)濃度:草甘膦(11個(gè)梯度)(mg·L-1):0.1、0.5、0.8、1、4、6、8、10、20、30、50;百草枯(8個(gè)梯度)(mg·L-1):1、3、5、8、10、20、40、60;異菌脲(7個(gè)梯度)(mg·L-1):5、10、30、60、90、120、150;代森錳鋅(7個(gè)梯度)(mg·L-1):20、60、100、120、150、200、220;三唑醇(7個(gè)梯度)(mg·L-1):100、300、500、800、1000、1300、1500;霜霉威(8個(gè)梯度)(mg·L-1):1、5、8、10、20、50、70、100;百菌清(6個(gè)梯度)(mg·L-1):100、500、1000、3000、5000、7000;速克靈(9個(gè)梯度)(mg·L-1):10、20、40、60、80、100、120、150、200.每種藥物每個(gè)濃度設(shè)3個(gè)平行,1個(gè)對(duì)照組,對(duì)照組為過濾海水.
2.2.2 配子的獲得及人工授精
挑選活力好、大小均一的海膽,采用KCl注射法(KCl濃度為0.5mol·L-1,注射1mL)催產(chǎn)獲得精子和卵(常亞青等,2004).將排精的雄海膽換入干的培養(yǎng)皿,以收集純凈的精液原液備用.將排卵的雌海膽放入盛有海水的三角燒瓶中,反口面向下,使海水淹蓋生殖孔,讓卵直接排入海水中,排出的卵逐漸沉入燒瓶底,顯微鏡下觀察卵子的質(zhì)量和精子的活性.卵子用篩絹網(wǎng)過濾,將精、卵直接于實(shí)驗(yàn)溶液中授精.
2.2.3 毒性實(shí)驗(yàn)
受精之后洗卵兩次,在盛有200mL實(shí)驗(yàn)溶液的250mL燒杯中發(fā)育,受精卵的密度大致為100~150個(gè)·mL-1,觀察胚胎發(fā)育過程.實(shí)驗(yàn)過程中選取6個(gè)發(fā)育期進(jìn)行觀察,分別為:二細(xì)胞期、四細(xì)胞期、上浮囊胚期、原腸期、棱柱幼體期和四腕幼蟲期,觀察記錄各藥物對(duì)海膽這6個(gè)發(fā)育期的影響情況.受精后即觀察對(duì)照組的受精情況,確保實(shí)驗(yàn)在90%以上的卵正常受精的情況下進(jìn)行.本實(shí)驗(yàn)條件下,對(duì)照組發(fā)育到二細(xì)胞需要1.5h,發(fā)育到四細(xì)胞需要2.5h,發(fā)育到上浮囊胚需要16.5h,發(fā)育到原腸需要28.5h,發(fā)育到棱柱幼體需要41h,發(fā)育到四腕幼蟲需要52h.觀察時(shí),每個(gè)平行隨機(jī)抽取100左右的個(gè)體,用5%甲醛固定,計(jì)數(shù).正常進(jìn)入各發(fā)育期的計(jì)為正常個(gè)體,發(fā)育延滯、畸形及死亡個(gè)體計(jì)為被抑制個(gè)體.
實(shí)驗(yàn)過程中間隔性充氣,以保證有充足的氧氣進(jìn)入實(shí)驗(yàn)水體,水溫控制在18℃.
2.3.1 EC50值的計(jì)算
檢查并統(tǒng)計(jì)各實(shí)驗(yàn)組海膽胚胎發(fā)育期的抑制率.利用SPSS 13.0軟件計(jì)算農(nóng)藥對(duì)海膽胚胎各發(fā)育期的EC50值.
2.3.2 LogP與EC50的相關(guān)性分析
利用Chmeoffice軟件計(jì)算出8種農(nóng)藥的LogP值,利用SPSS 13.0軟件對(duì)LogP與EC50的相關(guān)性進(jìn)行作圖并分析.
3.1.1 EC50值
8種農(nóng)藥對(duì)海膽胚胎各發(fā)育期的EC50值如表1所示.由表1可見,百菌清對(duì)海膽胚胎各發(fā)育期的EC50值在8種農(nóng)藥中均為最大;二細(xì)胞期EC50值最小的是百草枯;其他各發(fā)育期EC50最小的是草甘膦;霜霉威和代森錳鋅對(duì)于二細(xì)胞期的抑制率隨濃度變化不明顯且低,因此未計(jì)算出這兩種農(nóng)藥對(duì)二細(xì)胞期的EC50值.
以四腕幼蟲期的EC50值來看,8種農(nóng)藥的毒性大小依次為草甘膦>百草枯>代森錳鋅>速克靈>霜霉威>異菌脲>三唑醇>百菌清.
表1 8種農(nóng)藥對(duì)海膽胚胎各發(fā)育期的EC50值Table 1 EC50values of eight pesticides for the development of sea urchin embryos
3.1.2 海膽胚胎各發(fā)育期對(duì)農(nóng)藥的敏感性
EC50值隨海膽胚胎各發(fā)育期的變化如圖1所示.由圖1可見,隨著胚胎的發(fā)育,EC50逐漸降低,農(nóng)藥對(duì)胚胎的毒性逐漸增強(qiáng),表明隨著海膽胚胎的發(fā)育,其對(duì)農(nóng)藥的敏感性增強(qiáng),其中四腕幼蟲期最敏感,耐受性最低.
圖1 EC50值與海膽胚胎各發(fā)育期的關(guān)系Fig.1 Relationships between EC50values and sea urchin embryo development periods
海膽胚胎不同發(fā)育期對(duì)農(nóng)藥的耐受能力不同,可能主要與不同發(fā)育期的生理結(jié)構(gòu)有關(guān),上浮囊胚期之前的海膽胚胎有卵膜包裹,對(duì)毒性抵抗能力強(qiáng),原腸期腸道打開,對(duì)藥物抵抗力下降,到了棱柱期和四腕期胚胎完全暴露于藥液中,以至于很小的濃度就能引起抑制.
8種農(nóng)藥的LogP及結(jié)構(gòu)式如表2所示.
以農(nóng)藥的LogP值為橫坐標(biāo),以農(nóng)藥對(duì)海膽胚胎各發(fā)育期的EC50值為縱坐標(biāo),對(duì)LogP與EC50值的關(guān)系作圖.如圖2所示,隨著農(nóng)藥LogP的升高,各農(nóng)藥對(duì)不同發(fā)育期胚胎的EC50均呈逐漸上升趨勢(shì).回歸分析表明,原腸期和棱柱期的 EC50與 LogP有較好的正相關(guān)關(guān)系(p<0.05).
LogP是指平衡狀態(tài)下化合物在正辛醇和水相中濃度的比值,它反映了化合物在水相和有機(jī)相之間的遷移能力,表征的是化合物的親脂性(何藝兵等,1994).
化合物要對(duì)機(jī)體產(chǎn)生毒害作用,首先必須通過機(jī)體的細(xì)胞膜才能與目標(biāo)分子作用.細(xì)胞膜由磷脂雙分子層組成,親脂性的化合物比親水性的化合物更容易通過這一層細(xì)胞膜,因此細(xì)胞對(duì)藥物的吸收通常隨分配系數(shù)(LogP)的增加而增大(吳義輝等,2000),即LogP值越大,該化合物就越容易通過細(xì)胞膜,就可能對(duì)有機(jī)體造成更大的危害.理論上分子中氯原子數(shù)越多,分子的極性越小,其LogP的值越大,它對(duì)機(jī)體所造成的危害也可能越大(Richard and Hunter,1996).
表2 8種農(nóng)藥的LogP值Table 2 LogP values of eight pesticides
圖2 LogP與海膽胚胎各發(fā)育期EC50的關(guān)系Fig.2 Relationships between LogP values and EC50values during different sea urchin embryo development periods
然而,本實(shí)驗(yàn)結(jié)果發(fā)現(xiàn)EC50值與LogP呈正相關(guān),即隨著LogP的增大對(duì)海膽胚胎的毒性變小,與上述分析相反,此結(jié)果與孫雪峰等(2009)對(duì)光棘球海膽胚胎毒性試驗(yàn)中的現(xiàn)象一致.這可能與海膽胚胎細(xì)胞特殊的結(jié)構(gòu)和物質(zhì)組成有關(guān),也可能與農(nóng)藥在海水中與生物作用機(jī)制的不同有關(guān)(孫雪峰等,2009),還可能與LogP本身有關(guān).分配系數(shù)LogP值是對(duì)分子整體疏水性質(zhì)的定量表示,但不能描述分子的局域疏水性,而局域疏水性對(duì)于確定受體的活性位點(diǎn)和藥物分子的藥效團(tuán)非常重要(Kubinyi,1993).對(duì)于海膽胚胎而言,EC50值與農(nóng)藥LogP呈正相關(guān)性產(chǎn)生的具體機(jī)制目前尚不清楚,有待進(jìn)一步深入研究.
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AcuteToxicityofEightPesticideson theDevelopmentofSea Urchin Embryos
LI Jiao,WANG Heng,HAN Zhao-heng,SHI Sheng-bao,WANG Yong-hua,DING Jun*
Key Laboratory of Mariculture&Biotechnology,Ministry of Agriculture,Dalian Ocean University,Dalian 116023
1673-5897(2010)2-255-07
X171.5,X131.3
A
丁君(1973—),女,遼寧遼陽(yáng)市人,博士,副研究員,主要從事海洋生物技術(shù)方面的研究.
2009-12-10 錄用日期:2010-01-16
國(guó)家高技術(shù)研究發(fā)展計(jì)劃(863) 項(xiàng)目(No.2006AA10A411);國(guó)家海洋局海洋溢油鑒別與損害評(píng)估技術(shù)重點(diǎn)實(shí)驗(yàn)室開放基金項(xiàng)目
李嬌(1986—),女,碩士研究生;通訊作者(Corresponding author),E-mail:dingjunlll9@dlfu.edu.cn