魚類的生長主要受攝食和水溫的控製(Brett, 1979)。在zai冬dong季ji來lai臨lin時shi,水shui溫wen降jiang至zhi魚yu類lei生sheng長chang的de適shi宜yi溫wen度du以yi下xia,大da多duo數shu魚yu停ting止zhi攝she食shi,部bu分fen魚yu攝she食shi強qiang度du急ji劇ju下xia降jiang,但dan是shi在zai這zhe樣yang的de狀zhuang態tai下xia,魚yu類lei還hai是shi要yao通tong過guo消xiao耗hao能neng源yuan物wu質zhi來lai維wei持chi其qi基ji本ben的de生sheng命ming活huo動dong,所suo以yi機ji體ti必bi須xu做zuo出chu一yi係xi列lie變bian化hua來lai適shi應ying這zhe一yi極ji端duan狀zhuang態tai。魚yu類lei越yue冬dong的de適shi應ying過guo程cheng分fen為wei4個階段,分別是初冬的緊張期和適應期、越冬中期的穩定期以及越冬末期的恢複期。在整個越冬期間,魚類適應低溫和饑餓的反應及機理主要體現在其生長和形態學指標、魚體體組成和血液指標三個方麵。
1. 生長和形態學指標變化
yuleiyuedongqijian,getitizhongxianzhexiajiangshishiyingdiwenhejieshuangzhongyalidejieguo,zaishiwukuifahuotingshideqingkuangxiayuleizhinengxiaohaojitizishenchucundenengliangwuzhilaiweichijibendeshengminghuodong,jihusuoyouyuedongjieyuleidouchuxianletizhongheganzhongdexianzhexiajiang(Pastoureaud, 1991;陳立僑等, 1993; Kim和Lovell, 1995)。
已yi經jing有you大da量liang研yan究jiu表biao明ming饑ji餓e對dui於yu體ti重zhong的de影ying響xiang要yao大da於yu低di溫wen,在zai越yue冬dong期qi間jian持chi續xu或huo間jian斷duan性xing攝she食shi的de魚yu類lei體ti重zhong有you所suo增zeng加jia,而er沒mei有you喂wei食shi的de魚yu類lei體ti重zhong顯xian著zhe減jian少shao,說shuo明ming冬dong季ji魚yu體ti重zhong的de下xia降jiang更geng多duo的de受shou到dao饑ji餓e的de影ying響xiang(Lovell和Sirikul, 1974; Reagna和Robinette, 1978; Bastrop等, 1991; Kim和Lovell, 1995)。Kim和Lovell(1995)發現越冬期間連續攝食的斑點叉尾鮰與間斷攝食(12月、1月和2月不投喂)的斑點叉尾鮰相比,體重沒有顯著的變化,而饑餓的魚與之相比,體重差異明顯。越冬的草魚也有類似的結果(陳立僑等,1993),投喂較少的草魚魚種月增重率仍達2.3%,而同等條件下,饑餓組消瘦了3.43%。
相比較饑餓而言,溫度對越冬魚類體重的影響表現在兩個方麵:對(dui)於(yu)冬(dong)季(ji)還(hai)可(ke)攝(she)食(shi)的(de)魚(yu)來(lai)說(shuo),溫(wen)度(du)的(de)影(ying)響(xiang)主(zhu)要(yao)體(ti)現(xian)在(zai)食(shi)物(wu)的(de)轉(zhuan)化(hua)效(xiao)率(lv)上(shang),不(bu)管(guan)是(shi)連(lian)續(xu)投(tou)喂(wei)還(hai)是(shi)間(jian)斷(duan)性(xing)投(tou)喂(wei),魚(yu)類(lei)冬(dong)天(tian)的(de)餌(er)料(liao)轉(zhuan)化(hua)率(lv)都(dou)很(hen)低(di);另一方麵,溫度可能對饑餓有疊加效應。低溫時,可減少體重丟失,隨著溫度的升高,體重丟失更顯著(Kim和Lovell, 1995)。Pastoureaud(1991)的低溫饑餓試驗報道了舌齒鱸(Dicentrarchus labrax)的體重下降在饑餓的第一周更加顯著,並與馴化的溫度有很大關係。在3℃、7℃、8℃的溫度下,舌齒鱸體重下降的幅度不同,分別為37%、34%和42%,認為這是對低溫適應的代價。此外,舌齒鱸停食的溫度是7℃,低於或高於7℃,douyaoxiaohaogengduodenengliangqushiying,erqie,shiyanguochengzhongdexunhuashuiwenduiyuedongtingshideshechiludetizhongyeyouyingxiang,xunhuawendugaodeyutizhongjianshaochengdugengda。
梁友光(2005)研yan究jiu表biao明ming肥fei滿man度du的de變bian化hua與yu長chang吻wen鮠鮠魚yu體ti體ti重zhong的de變bian化hua非fei常chang相xiang似si,越yue冬dong期qi間jian肥fei滿man度du不bu斷duan減jian小xiao,並bing且qie在zai越yue冬dong初chu期qi的de緊jin張zhang期qi和he適shi應ying期qi尤you為wei顯xian著zhe,但dan在zai此ci後hou的de越yue冬dong過guo程cheng中zhong,並bing沒mei有you發fa生sheng明ming顯xian的de變bian化hua,說shuo明ming在zai越yue冬dong期qi間jian,長chang吻wen鮠鮠魚yu體ti體ti重zhong的de變bian化hua在zai越yue冬dong初chu期qi下xia降jiang最zui明ming顯xian,越yue冬dong後hou期qi下xia降jiang趨qu勢shi放fang緩huan。
肝髒是魚類中間代謝的主要器官,在營養不良或饑餓條件下,由於機能上的原因,其重量會有所變動;而er肝gan髒zang作zuo為wei魚yu體ti營ying養yang物wu質zhi的de儲chu藏zang器qi官guan,在zai低di溫wen或huo食shi物wu匱kui乏fa時shi,由you於yu要yao維wei持chi最zui基ji本ben的de代dai謝xie以yi及ji抵di抗kang環huan境jing溫wen度du變bian化hua的de影ying響xiang,魚yu類lei肝gan髒zang內nei儲chu藏zang的de能neng量liang物wu質zhi被bei消xiao耗hao,肝gan重zhong減jian小xiao,肝gan體ti指zhi數shu下xia降jiang(宋昭彬和何學福, 1998)。肝體指數被看作是魚類對長期和短期營養方式很敏感的形態學指標(梁友光, 2005)。Mustafa等(1991)發(fa)現(xian)舌(she)齒(chi)鱸(lu)在(zai)越(yue)冬(dong)開(kai)始(shi)後(hou)肝(gan)體(ti)指(zhi)數(shu)下(xia)降(jiang),到(dao)一(yi)月(yue)份(fen)降(jiang)至(zhi)最(zui)低(di),然(ran)後(hou)在(zai)二(er)月(yue)份(fen)轉(zhuan)而(er)上(shang)升(sheng),認(ren)為(wei)肝(gan)體(ti)指(zhi)數(shu)的(de)這(zhe)種(zhong)轉(zhuan)折(zhe)可(ke)能(neng)與(yu)此(ci)時(shi)水(shui)溫(wen)開(kai)始(shi)上(shang)升(sheng)、白晝不斷延長等環境因素的改變有關。
梁友光(2005)yanjiufaxianzangtizhishufanyingleyutineizangzhongliangdebianhua,zaidiwenxiepodeqingkuangxia,yuleidongyongfuzhilaimanzunengliangxuqiu,bingqiesuiwendudejiangdidongyongfuzhidechengdujiaqiang,zaidiwenhejieshuangzhongxiepodetiaojianxia,youyufuzhidedafuduxiaohaoershideneizangzhongliangxianzhexiajiang。Bosworth和Woletrs(2005)發fa現xian髒zang體ti指zhi數shu隨sui魚yu攝she食shi條tiao件jian的de好hao壞huai而er改gai變bian,穩wen定ding攝she食shi的de魚yu,其qi髒zang體ti指zhi數shu高gao於yu限xian製zhi攝she食shi的de魚yu,而er攝she食shi的de魚yu又you高gao於yu不bu攝she食shi的de魚yu。此ci外wai,在zai魚yu類lei正zheng常chang攝she食shi的de情qing況kuang下xia,腹fu脂zhi儲chu留liu程cheng度du顯xian著zhe高gao於yu其qi他ta攝she食shi不bu良liang的de魚yu。
2. 魚體體組成變化
魚(yu)類(lei)越(yue)冬(dong)的(de)適(shi)應(ying)過(guo)程(cheng)表(biao)現(xian)在(zai)魚(yu)體(ti)體(ti)組(zu)成(cheng)的(de)變(bian)化(hua)為(wei)在(zai)越(yue)冬(dong)結(jie)束(shu)時(shi)肌(ji)肉(rou)中(zhong)的(de)水(shui)分(fen)含(han)量(liang)顯(xian)著(zhe)上(shang)升(sheng),魚(yu)體(ti)的(de)脂(zhi)肪(fang)和(he)蛋(dan)白(bai)質(zhi)含(han)量(liang)顯(xian)著(zhe)降(jiang)低(di),肝(gan)髒(zang)中(zhong)的(de)脂(zhi)肪(fang)和(he)糖(tang)原(yuan)顯(xian)著(zhe)減(jian)少(shao),肌(ji)肉(rou)和(he)肝(gan)髒(zang)中(zhong)的(de)飽(bao)和(he)脂(zhi)肪(fang)酸(suan)和(he)單(dan)不(bu)飽(bao)和(he)脂(zhi)肪(fang)酸(suan)含(han)量(liang)顯(xian)著(zhe)減(jian)少(shao),魚(yu)體(ti)脂(zhi)肪(fang)酸(suan)的(de)不(bu)飽(bao)和(he)性(xing)增(zeng)高(gao)。
Bastrop等(1991)認(ren)為(wei)由(you)於(yu)越(yue)冬(dong)期(qi)間(jian)魚(yu)體(ti)停(ting)食(shi)且(qie)體(ti)內(nei)能(neng)源(yuan)物(wu)質(zhi)不(bu)斷(duan)消(xiao)耗(hao),使(shi)饑(ji)餓(e)魚(yu)體(ti)代(dai)謝(xie)的(de)一(yi)些(xie)內(nei)源(yuan)性(xing)物(wu)質(zhi)被(bei)水(shui)取(qu)代(dai),導(dao)致(zhi)含(han)水(shui)量(liang)和(he)灰(hui)分(fen)含(han)量(liang)逐(zhu)漸(jian)上(shang)升(sheng)。梁(liang)友(you)光(guang)(2005)的研究發現長吻鮠肌肉水分含量隨越冬時間的延長而增加,說明了越冬過程中肌肉組織的一些營養物質被消耗,但在越冬20tianshi,shuifenhanliangchuxianjianshaodexianxiang,ertongyishijian,danbaizhihanliangyouyigetisheng,zhezhongxianxiangyexuyushileyuedongqianqiyutiduidiwenhejiedeshiyinghetiaozheng,zaiyidingtiaozhenghoushuifenhanliangzaicizengjia,bingzaiyuedongjieshushixianzhegaoyuyuedongkaishishi。
越冬期間魚類動用機體貯存的能量來維持生命活動,作為主要貯能物質的糖原、脂(zhi)肪(fang)和(he)蛋(dan)白(bai)質(zhi)在(zai)越(yue)冬(dong)過(guo)程(cheng)中(zhong)將(jiang)會(hui)不(bu)同(tong)程(cheng)度(du)地(di)被(bei)消(xiao)耗(hao)。在(zai)越(yue)冬(dong)開(kai)始(shi)的(de)過(guo)程(cheng)中(zhong),溫(wen)度(du)這(zhe)個(ge)因(yin)子(zi)的(de)變(bian)化(hua)對(dui)魚(yu)體(ti)施(shi)加(jia)了(le)影(ying)響(xiang),從(cong)而(er)改(gai)變(bian)了(le)其(qi)代(dai)謝(xie)水(shui)平(ping),尤(you)其(qi)在(zai)初(chu)期(qi),魚(yu)類(lei)為(wei)了(le)應(ying)對(dui)並(bing)適(shi)應(ying)這(zhe)種(zhong)環(huan)境(jing)的(de)改(gai)變(bian),將(jiang)會(hui)加(jia)大(da)能(neng)量(liang)的(de)消(xiao)耗(hao),因(yin)此(ci)相(xiang)應(ying)的(de)肌(ji)肉(rou)粗(cu)蛋(dan)白(bai)和(he)粗(cu)脂(zhi)肪(fang)含(han)量(liang)都(dou)會(hui)出(chu)現(xian)不(bu)同(tong)程(cheng)度(du)的(de)下(xia)降(jiang)。在(zai)多(duo)數(shu)魚(yu)類(lei)中(zhong),脂(zhi)肪(fang)和(he)糖(tang)原(yuan)是(shi)主(zhu)要(yao)的(de)貯(zhu)能(neng)物(wu)質(zhi),由(you)於(yu)蛋(dan)白(bai)質(zhi)的(de)關(guan)鍵(jian)代(dai)謝(xie)酶(mei)穀(gu)氨(an)酸(suan)轉(zhuan)氨(an)酶(mei)的(de)活(huo)性(xing)在(zai)20℃時下降,導致蛋白質分解速率降低,從而在饑餓過程中首先主要消耗脂肪和糖原,然後才較多地利用蛋白質(Mehner和Wieser, 1994)。如大西洋鱈(Gadus morhua)以及一些軟骨魚類,饑餓時優先動用脂肪,日本鰻鱺(Anguilla japonica)則利用糖原和脂肪,保存蛋白質(Bernard等, 1976)。Bastrop等(1991)指zhi出chu魚yu類lei在zai饑ji餓e時shi糖tang原yuan消xiao耗hao快kuai於yu脂zhi肪fang,脂zhi肪fang用yong於yu維wei持chi糖tang原yuan異yi生sheng作zuo用yong,而er脂zhi肪fang分fen解jie代dai謝xie產chan物wu用yong作zuo糖tang原yuan合he成cheng代dai謝xie的de基ji質zhi,這zhe一yi過guo程cheng在zai越yue冬dong的de最zui初chu幾ji天tian產chan生sheng,並bing持chi續xu到dao蛋dan白bai質zhi開kai始shi用yong於yu產chan生sheng能neng量liang。
Pastoureaud(1991)指出,在低溫時肝脂肪和肝糖原下降而水分明顯增加。很明顯,舌齒鱸在3℃時動員脂肪,而7℃和11℃時利用糖原,而在饑餓第二周,11℃shiliyongzhifanghetangyuanchanshengnengliang。jirantangyuanbunengwanquanmanzuyudenengliangxuqiu,namejiudedongyongzhifang,zaiyubaozhengtangyuanshuipingbuzhiyujiangzhiyouhaiyuqiguandaixiedechengdu。
淡水魚類在越冬過程中優先利用碳鏈較短、飽和性較高的脂肪酸,越冬期間脂肪酸不飽和性增高(童聖英, 1997)。隨(sui)著(zhe)環(huan)境(jing)溫(wen)度(du)的(de)下(xia)降(jiang),細(xi)胞(bao)膜(mo)的(de)流(liu)動(dong)性(xing)降(jiang)低(di),從(cong)而(er)使(shi)酶(mei)活(huo)力(li)下(xia)降(jiang)。魚(yu)類(lei)針(zhen)對(dui)溫(wen)度(du)變(bian)化(hua),增(zeng)加(jia)膜(mo)的(de)流(liu)動(dong)性(xing),以(yi)補(bu)償(chang)它(ta)對(dui)酶(mei)活(huo)力(li)的(de)影(ying)響(xiang)。膜(mo)的(de)流(liu)動(dong)性(xing)主(zhu)要(yao)取(qu)決(jue)於(yu)脂(zhi)類(lei)分(fen)子(zi),由(you)於(yu)不(bu)飽(bao)和(he)脂(zhi)肪(fang)酸(suan)具(ju)有(you)較(jiao)低(di)的(de)溶(rong)點(dian),在(zai)單(dan)層(ceng)膜(mo)結(jie)構(gou)中(zhong)占(zhan)據(ju)的(de)位(wei)置(zhi)比(bi)其(qi)飽(bao)和(he)的(de)同(tong)源(yuan)脂(zhi)肪(fang)酸(suan)大(da),所(suo)以(yi)脂(zhi)肪(fang)酸(suan)中(zhong)長(chang)鏈(lian)不(bu)飽(bao)和(he)脂(zhi)肪(fang)酸(suan)(特別是DHA)和多不飽和脂肪酸比例的增加,增加了膜雙層組織的無序性,因而使膜的流動性增加,這種反應是膜流動性對於溫度適應的表現(童聖英, 1997)。Lovell(1989)指出魚的脂肪酸需求取決於溫度,低溫下生活的魚類如鮭魚需要n-3係列的脂肪酸,因為n-3結構可以允許的雙鍵數目多,這是魚在低溫下磷脂膜保持柔軟性和滲透性所必不可少的。降低脂肪酸熔點、tigaomozhiliudongxingzhuyaoyikaochanglianbubaohezhifangsuan,danxisuandezuoyongyuanbujiduoxisuan,suoyiyuleizaiyuedongshiyidanxisuandejianshaolaibaozhengduoxisuanhanliangdewending。
yuedongqijian,ganzangdebubaohezhifangsuanjianshao,yifangmianyushileganxibaomodeliudongxingbiancha,lingyifangmianganzangweileweichijitijibendeshengligongneng,tongguozengjiaduoxisuandebililaizengjiamodeliudongxingheshentounengli。shentoutiaojienenglidesunhaibeiyonglaijieshigezhongdanshuihehaishuiyuleidiwenshichenghuolvdexiajiang(Wikgern, 1953; Hochachka, 1988; Belkovsky等, 1992)。膜通透性的變化和離子轉運機製的破壞降低了魚對低溫的滲透調節能力(Wikgern1953; Morris和Bull, 1968; Schwarzbaum等, 1991)。yuedongqijian,jirouheganzangduoxisuanbilijibenbaochiwendinghuoshenggao,shiweilebaozhengmodeliudongxinghetigaodiwenxiadeshentoutiaojienenglierbaozhengchenghuolvsuozuodedaixietiaozheng。ciwai,Jezierska等(1982)faxianzaishiwunifashi,yuleiyouxianliyongdanxisuankenenggengyouliyunengliangdeshifangheliyong,erjitihechengduobubaohezhifangsuansuohaonengliangjiaoda,youxianliyongdanxisuanyijiyanhuanduiduoxisuandeliyong,duijitieryanshiyoulide。
3. 血液指標變化
魚類越冬的適應過程表現在血液指標上為紅細胞數量在越冬過程中不斷下降,白細胞數量在越冬前期上升,到了一定階段後開始下降;血糖、膽固醇、甘油三脂含量在越冬初期有所下降,隨後上升,並恢複到正常水平或者顯著高於正常水平;血清總蛋白含量隨越冬時間的延長而逐漸下降。
血液是動物體內一種非常重要的物質。血液指標能反映某個物種的屬性以及生理狀態(Bollard等, 1993; Hlavova, 1993; Takeda, 1993; Yrtestoyl等, 2001; Fijna, 2002)。魚類是一種變溫動物,其體溫是隨著外界環境的變化而變化的,其血液與機體的代謝、yingyangjijibingdouyouzhefeichangmiqiedeguanxi,dangyuleiyinweishoudaowaijiehuanjingyinzideyingxiangerfashengshenglihuobinglibianhuashi,huoduohuoshaodouhuizaixueyezhibiaozhongfanyingchulai。
youyuhongxibaohexuehongdanbaidetexing,shidehongxibaokeyizaihendachengdushangjuedingyangdeyunshunengli,yinciqishulianghetijidebianhuayingxianglejitidedaixiexingneng,tongshicongbaixibaodeshuliangbianhuayenengjieshichujitimianyigongnengdegaibian。youyushoudaolediwenhuanjingdexiepofanying,yuleihuodongnenglihedaixiejinengxiajiangshidehongxibaoshuxianzhejiangdi。zaiyuedongchuqi,diwenhejieduiyuchanshenglexiepo,xueyezhongdebaixibaoshuliangdejijushenggaobiaominglejitiduiyuhuanjingdeshiyinghetiaozheng,dangjitishiyingdongjidehuanjingtiaojianhou,baixibaoshuliangbianjibenhuifudaoleyiqiandeshuiping。shenwenyingdeng(2003)對饑餓銀鯽的研究結果顯示,饑餓2周後,銀鯽白細胞數量顯著上升。梁友光(2005)發現長吻鮠在越冬前期白細胞數量有一個顯著的升高,而後在越冬50天(tian)時(shi)下(xia)降(jiang),這(zhe)種(zhong)現(xian)象(xiang)應(ying)對(dui)了(le)長(chang)吻(wen)鮠(鮠)對(dui)水(shui)溫(wen)和(he)攝(she)食(shi)狀(zhuang)態(tai)的(de)變(bian)動(dong)。在(zai)越(yue)冬(dong)初(chu)期(qi),低(di)溫(wen)和(he)饑(ji)餓(e)對(dui)長(chang)吻(wen)魷(you)產(chan)生(sheng)了(le)脅(xie)迫(po),長(chang)吻(wen)鮠(鮠)白(bai)細(xi)胞(bao)數(shu)量(liang)的(de)急(ji)劇(ju)升(sheng)高(gao)表(biao)明(ming)了(le)機(ji)體(ti)對(dui)於(yu)環(huan)境(jing)的(de)適(shi)應(ying)和(he)調(tiao)整(zheng),在(zai)越(yue)冬(dong)50天逐漸適應後魚體的免疫反應減弱。
yuleishoudaodiwenxiepo,jitixuyaodaliangdenenglianglaidikanghuanjingdebianhua,xuetangbeidaliangxiaohao,tongshidiwenshiyutidaixiexiajiang,tineigezhongmeidehuoxingxiajiang,tangyuanfenjiejitangyishengtujingjianhuan,zhongzhongyinsudaozhileyuleizaiyuedongguochengzhongxuetangxianzhejiangdi(錢雲霞等, 2002)。dangsuizheyuedongguochengdeshenru,yutiduihuanjingdebianhuayouyidingdetiaozhengheshiyingnengli,zaizhujianshiyinghuanjingbianhuahou,tineiquyuxindewentai,tongshidanbaizhihezhifangwuzhidexiaohaoshitangyishengtujingjiaqiang,xuetanghanliangbuduanshangsheng,zuizhonghuifuzhizhengchangshuiping。youguanyanjiuyezengzhichu,xuetangdeweichizhuyaokaotangyishengzuoyong(孫紅梅, 2004;錢雲霞等, 2002)。
血(xue)清(qing)中(zhong)甘(gan)油(you)三(san)酯(zhi)和(he)總(zong)膽(dan)固(gu)醇(chun)的(de)量(liang)分(fen)別(bie)代(dai)表(biao)了(le)機(ji)體(ti)能(neng)夠(gou)攝(she)取(qu)或(huo)合(he)成(cheng)甘(gan)油(you)三(san)酯(zhi)和(he)膽(dan)固(gu)醇(chun)的(de)多(duo)少(shao)。越(yue)冬(dong)過(guo)程(cheng)中(zhong),魚(yu)體(ti)血(xue)清(qing)中(zhong)甘(gan)油(you)三(san)酯(zhi)和(he)膽(dan)固(gu)醇(chun)在(zai)初(chu)期(qi)開(kai)始(shi)降(jiang)低(di),說(shuo)明(ming)作(zuo)為(wei)能(neng)源(yuan)物(wu)質(zhi)的(de)甘(gan)油(you)三(san)酯(zhi)被(bei)大(da)量(liang)消(xiao)耗(hao),同(tong)時(shi)低(di)溫(wen)脅(xie)迫(po)使(shi)魚(yu)體(ti)代(dai)謝(xie)下(xia)降(jiang),各(ge)種(zhong)酶(mei)的(de)活(huo)性(xing)降(jiang)低(di),兩(liang)種(zhong)物(wu)質(zhi)的(de)合(he)成(cheng)減(jian)緩(huan)(何福林等, 2007)。隨(sui)著(zhe)越(yue)冬(dong)時(shi)間(jian)的(de)延(yan)長(chang),機(ji)體(ti)不(bu)斷(duan)的(de)調(tiao)整(zheng)和(he)適(shi)應(ying),兩(liang)種(zhong)物(wu)質(zhi)含(han)量(liang)不(bu)斷(duan)上(shang)升(sheng),最(zui)終(zhong)在(zai)越(yue)冬(dong)末(mo)期(qi)總(zong)膽(dan)固(gu)醇(chun)回(hui)升(sheng)至(zhi)正(zheng)常(chang)水(shui)平(ping),而(er)甘(gan)油(you)三(san)酯(zhi)顯(xian)著(zhe)高(gao)於(yu)正(zheng)常(chang)水(shui)平(ping),可(ke)能(neng)是(shi)與(yu)膜(mo)的(de)通(tong)透(tou)性(xing)有(you)關(guan)。常(chang)玉(yu)梅(mei)等(deng)(2006)的研究認為,動植物的抗寒特性與細胞膜膜脂的組成和結構有關,其中最為流行的學說是Lyons提出的“膜脂相變”學說,該學說認為膜脂不飽和脂肪酸含量高,膜的相變溫度就低,因此可以通過操縱脂肪酸脫飽和反應來改善抗寒性(張羽航, 2001)。魚yu類lei的de脂zhi肪fang酸suan代dai謝xie對dui體ti溫wen降jiang低di的de適shi應ying很hen敏min感gan,通tong過guo積ji累lei長chang鏈lian不bu飽bao和he脂zhi肪fang酸suan的de含han量liang,可ke以yi使shi膜mo在zai低di溫wen脅xie迫po時shi仍reng保bao持chi穩wen定ding性xing和he流liu動dong性xing,從cong而er提ti高gao自zi身shen的de抗kang寒han能neng力li。越yue冬dong結jie束shu時shi甘gan油you三san酯zhi含han量liang顯xian著zhe高gao於yu正zheng常chang水shui平ping,可ke能neng是shi由you於yu低di溫wen誘you導dao不bu飽bao和he脂zhi肪fang酸suan含han量liang增zeng加jia的de結jie果guo(Tyler和Dunn, 1976)。
血(xue)清(qing)中(zhong)蛋(dan)白(bai)質(zhi)分(fen)為(wei)兩(liang)種(zhong),一(yi)種(zhong)是(shi)白(bai)蛋(dan)白(bai),一(yi)種(zhong)是(shi)球(qiu)蛋(dan)白(bai)。白(bai)蛋(dan)白(bai)可(ke)以(yi)修(xiu)補(bu)組(zu)織(zhi),還(hai)可(ke)以(yi)維(wei)持(chi)血(xue)漿(jiang)交(jiao)替(ti)滲(shen)透(tou)壓(ya)。球(qiu)蛋(dan)白(bai)是(shi)免(mian)疫(yi)性(xing)抗(kang)體(ti),參(can)與(yu)機(ji)體(ti)特(te)異(yi)性(xing)免(mian)疫(yi)。血(xue)清(qing)總(zong)蛋(dan)白(bai)可(ke)以(yi)用(yong)來(lai)診(zhen)斷(duan)魚(yu)類(lei)的(de)健(jian)康(kang)、營養和疾病狀況。一般認為饑餓會引起總蛋白、白蛋白和球蛋白減少(趙海濤, 2006)。越yue冬dong初chu期qi低di溫wen脅xie迫po使shi魚yu體ti出chu現xian應ying激ji反fan應ying,魚yu體ti為wei了le抵di抗kang環huan境jing的de變bian化hua,體ti內nei合he成cheng了le大da量liang的de球qiu蛋dan白bai用yong以yi防fang禦yu病bing害hai的de入ru侵qin,越yue冬dong後hou期qi,血xue清qing蛋dan白bai含han量liang出chu現xian了le不bu同tong程cheng度du的de下xia降jiang,應ying該gai是shi長chang期qi的de低di溫wen脅xie迫po使shi魚yu體ti肝gan髒zang受shou到dao一yi定ding程cheng度du的de損sun傷shang,導dao致zhi肝gan髒zang合he成cheng蛋dan白bai的de能neng力li下xia降jiang,同tong時shi也ye說shuo明ming機ji體ti的de組zu織zhi修xiu補bu、滲透壓調節等生理功能均受到影響(孫紅梅, 2004)。
4. 總結
越冬過程中魚類在受到低溫和饑餓的雙重壓力下,在初期產生了強烈的應激反應,此後不斷通過消耗魚體自身儲存的脂肪、糖原、danbaizhidengnengyuanwuzhiweichijitidezhengchangdaixieheshengminghuodong,bingqietongguoneibutiaojietigaolezhifangsuandebubaohexinghexueyezhongmianyixibaodehanliang,congerzengjialeyutishengwumodeliudongxing、shentouyatiaojienenglihemianyinengli。zhexieyuedongguochengzhongyutichanshengdesuoyoutiaojieheshiyingfanyingdemudezhiyouyige,jiushitigaoyuleizaiyuedongguochengzhongdechenghuolv,shiqinengshunliduguozheyijiduanshiqi。
文/廣州市誠一水產科技有限公司 李如偉
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