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
魚yu類lei越yue冬dong期qi間jian,個ge體ti體ti重zhong顯xian著zhe下xia降jiang是shi適shi應ying低di溫wen和he饑ji餓e雙shuang重zhong壓ya力li的de結jie果guo,在zai食shi物wu匱kui乏fa或huo停ting食shi的de情qing況kuang下xia魚yu類lei隻zhi能neng消xiao耗hao機ji體ti自zi身shen儲chu存cun的de能neng量liang物wu質zhi來lai維wei持chi基ji本ben的de生sheng命ming活huo動dong,幾ji乎hu所suo有you越yue冬dong饑ji餓e魚yu類lei都dou出chu現xian了le體ti重zhong和he肝gan重zhong的de顯xian著zhe下xia降jiang(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:duiyudongjihaikesheshideyulaishuo,wendudeyingxiangzhuyaotixianzaishiwudezhuanhuaxiaolvshang,buguanshilianxutouweihaishijianduanxingtouwei,yuleidongtiandeerliaozhuanhualvdouhendi;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)研yan究jiu發fa現xian髒zang體ti指zhi數shu反fan映ying了le魚yu體ti內nei髒zang重zhong量liang的de變bian化hua,在zai低di溫wen脅xie迫po的de情qing況kuang下xia,魚yu類lei動dong用yong腹fu脂zhi來lai滿man足zu能neng量liang需xu求qiu,並bing且qie隨sui溫wen度du的de降jiang低di動dong用yong腹fu脂zhi的de程cheng度du加jia強qiang,在zai低di溫wen和he饑ji餓e雙shuang重zhong脅xie迫po的de條tiao件jian下xia,由you於yu腹fu脂zhi的de大da幅fu度du消xiao耗hao而er使shi得de內nei髒zang重zhong量liang顯xian著zhe下xia降jiang。Bosworth和Woletrs(2005)faxianzangtizhishusuiyusheshitiaojiandehaohuaiergaibian,wendingsheshideyu,qizangtizhishugaoyuxianzhisheshideyu,ersheshideyuyougaoyubusheshideyu。ciwai,zaiyuleizhengchangsheshideqingkuangxia,fuzhichuliuchengduxianzhegaoyuqitasheshibuliangdeyu。
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20天(tian)時(shi),水(shui)分(fen)含(han)量(liang)出(chu)現(xian)減(jian)少(shao)的(de)現(xian)象(xiang),而(er)同(tong)一(yi)時(shi)間(jian),蛋(dan)白(bai)質(zhi)含(han)量(liang)有(you)一(yi)個(ge)提(ti)升(sheng),這(zhe)種(zhong)現(xian)象(xiang)也(ye)許(xu)預(yu)示(shi)了(le)越(yue)冬(dong)前(qian)期(qi)魚(yu)體(ti)對(dui)低(di)溫(wen)和(he)饑(ji)餓(e)的(de)適(shi)應(ying)和(he)調(tiao)整(zheng),在(zai)一(yi)定(ding)調(tiao)整(zheng)後(hou)水(shui)分(fen)含(han)量(liang)再(zai)次(ci)增(zeng)加(jia),並(bing)在(zai)越(yue)冬(dong)結(jie)束(shu)時(shi)顯(xian)著(zhe)高(gao)於(yu)越(yue)冬(dong)開(kai)始(shi)時(shi)。
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zai20℃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℃時(shi)利(li)用(yong)脂(zhi)肪(fang)和(he)糖(tang)原(yuan)產(chan)生(sheng)能(neng)量(liang)。既(ji)然(ran)糖(tang)原(yuan)不(bu)能(neng)完(wan)全(quan)滿(man)足(zu)魚(yu)的(de)能(neng)量(liang)需(xu)求(qiu),那(na)麼(me)就(jiu)得(de)動(dong)用(yong)脂(zhi)肪(fang),在(zai)於(yu)保(bao)證(zheng)糖(tang)原(yuan)水(shui)平(ping)不(bu)至(zhi)於(yu)降(jiang)至(zhi)有(you)害(hai)於(yu)器(qi)官(guan)代(dai)謝(xie)的(de)程(cheng)度(du)。
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)發fa現xian在zai食shi物wu匿ni乏fa時shi,魚yu類lei優you先xian利li用yong單dan烯xi酸suan可ke能neng更geng有you利li於yu能neng量liang的de釋shi放fang和he利li用yong,而er機ji體ti合he成cheng多duo不bu飽bao和he脂zhi肪fang酸suan所suo耗hao能neng量liang較jiao大da,優you先xian利li用yong單dan烯xi酸suan以yi及ji延yan緩huan對dui多duo烯xi酸suan的de利li用yong,對dui機ji體ti而er言yan是shi有you利li的de。
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、營(ying)養(yang)及(ji)疾(ji)病(bing)都(dou)有(you)著(zhe)非(fei)常(chang)密(mi)切(qie)的(de)關(guan)係(xi),當(dang)魚(yu)類(lei)因(yin)為(wei)受(shou)到(dao)外(wai)界(jie)環(huan)境(jing)因(yin)子(zi)的(de)影(ying)響(xiang)而(er)發(fa)生(sheng)生(sheng)理(li)或(huo)病(bing)理(li)變(bian)化(hua)時(shi),或(huo)多(duo)或(huo)少(shao)都(dou)會(hui)在(zai)血(xue)液(ye)指(zhi)標(biao)中(zhong)反(fan)映(ying)出(chu)來(lai)。
由you於yu紅hong細xi胞bao和he血xue紅hong蛋dan白bai的de特te性xing,使shi得de紅hong細xi胞bao可ke以yi在zai很hen大da程cheng度du上shang決jue定ding氧yang的de運yun輸shu能neng力li,因yin此ci其qi數shu量liang和he體ti積ji的de變bian化hua影ying響xiang了le機ji體ti的de代dai謝xie性xing能neng,同tong時shi從cong白bai細xi胞bao的de數shu量liang變bian化hua也ye能neng揭jie示shi出chu機ji體ti免mian疫yi功gong能neng的de改gai變bian。由you於yu受shou到dao了le低di溫wen環huan境jing的de脅xie迫po反fan映ying,魚yu類lei活huo動dong能neng力li和he代dai謝xie機ji能neng下xia降jiang使shi得de紅hong細xi胞bao數shu顯xian著zhe降jiang低di。在zai越yue冬dong初chu期qi,低di溫wen和he饑ji餓e對dui魚yu產chan生sheng了le脅xie迫po,血xue液ye中zhong的de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,當dang機ji體ti適shi應ying冬dong季ji的de環huan境jing條tiao件jian後hou,白bai細xi胞bao數shu量liang便bian基ji本ben恢hui複fu到dao了le以yi前qian的de水shui平ping。沈shen文wen英ying等deng(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dong50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)。當(dang)隨(sui)著(zhe)越(yue)冬(dong)過(guo)程(cheng)的(de)深(shen)入(ru),魚(yu)體(ti)對(dui)環(huan)境(jing)的(de)變(bian)化(hua)有(you)一(yi)定(ding)的(de)調(tiao)整(zheng)和(he)適(shi)應(ying)能(neng)力(li),在(zai)逐(zhu)漸(jian)適(shi)應(ying)環(huan)境(jing)變(bian)化(hua)後(hou),體(ti)內(nei)趨(qu)於(yu)新(xin)的(de)穩(wen)態(tai),同(tong)時(shi)蛋(dan)白(bai)質(zhi)和(he)脂(zhi)肪(fang)物(wu)質(zhi)的(de)消(xiao)耗(hao)使(shi)糖(tang)異(yi)生(sheng)途(tu)徑(jing)加(jia)強(qiang),血(xue)糖(tang)含(han)量(liang)不(bu)斷(duan)上(shang)升(sheng),最(zui)終(zhong)恢(hui)複(fu)至(zhi)正(zheng)常(chang)水(shui)平(ping)。有(you)關(guan)研(yan)究(jiu)也(ye)曾(zeng)指(zhi)出(chu),血(xue)糖(tang)的(de)維(wei)持(chi)主(zhu)要(yao)靠(kao)糖(tang)異(yi)生(sheng)作(zuo)用(yong)(孫紅梅, 2004;錢雲霞等, 2002)。
xueqingzhongganyousanzhihezongdanguchundeliangfenbiedaibiaolejitinenggoushequhuohechengganyousanzhihedanguchundeduoshao。yuedongguochengzhong,yutixueqingzhongganyousanzhihedanguchunzaichuqikaishijiangdi,shuomingzuoweinengyuanwuzhideganyousanzhibeidaliangxiaohao,tongshidiwenxieposhiyutidaixiexiajiang,gezhongmeidehuoxingjiangdi,liangzhongwuzhidehechengjianhuan(何福林等, 2007)。suizheyuedongshijiandeyanchang,jitibuduandetiaozhengheshiying,liangzhongwuzhihanliangbuduanshangsheng,zuizhongzaiyuedongmoqizongdanguchunhuishengzhizhengchangshuiping,erganyousanzhixianzhegaoyuzhengchangshuiping,kenengshiyumodetongtouxingyouguan。changyumeideng(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)。yuleidezhifangsuandaixieduitiwenjiangdideshiyinghenmingan,tongguojileichanglianbubaohezhifangsuandehanliang,keyishimozaidiwenxieposhirengbaochiwendingxingheliudongxing,congertigaozishendekanghannengli。yuedongjieshushiganyousanzhihanliangxianzhegaoyuzhengchangshuiping,kenengshiyouyudiwenyoudaobubaohezhifangsuanhanliangzengjiadejieguo(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、蛋dan白bai質zhi等deng能neng源yuan物wu質zhi維wei持chi機ji體ti的de正zheng常chang代dai謝xie和he生sheng命ming活huo動dong,並bing且qie通tong過guo內nei部bu調tiao節jie提ti高gao了le脂zhi肪fang酸suan的de不bu飽bao和he性xing和he血xue液ye中zhong免mian疫yi細xi胞bao的de含han量liang,從cong而er增zeng加jia了le魚yu體ti生sheng物wu膜mo的de流liu動dong性xing、滲(shen)透(tou)壓(ya)調(tiao)節(jie)能(neng)力(li)和(he)免(mian)疫(yi)能(neng)力(li)。這(zhe)些(xie)越(yue)冬(dong)過(guo)程(cheng)中(zhong)魚(yu)體(ti)產(chan)生(sheng)的(de)所(suo)有(you)調(tiao)節(jie)和(he)適(shi)應(ying)反(fan)應(ying)的(de)目(mu)的(de)隻(zhi)有(you)一(yi)個(ge),就(jiu)是(shi)提(ti)高(gao)魚(yu)類(lei)在(zai)越(yue)冬(dong)過(guo)程(cheng)中(zhong)的(de)成(cheng)活(huo)率(lv),使(shi)其(qi)能(neng)順(shun)利(li)度(du)過(guo)這(zhe)一(yi)極(ji)端(duan)時(shi)期(qi)。
文/廣州市誠一水產科技有限公司 李如偉
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