梭魚養(yǎng)殖與自然的遺傳芻議

梭魚養(yǎng)殖與自然的遺傳芻議以梭魚尾鰭鰭條為材料,采用苯酚一氯仿抽提法提取基因組DNA后，于4°C條件下避光保存?zhèn)溆?，引物與反應(yīng)條件。RAPD反應(yīng)總體系為30p1,其中含有10XBuffer3p1、dNTP(各2.5mmo1/L)0.4^1、Primer(100pmo1/L)0.24p1、TaqDNA聚合酶(5U/p1)0.3p1、模板DNA0.3pg。RAPD反應(yīng)程序包括35個循環(huán):94C變性1min,36C退火1min,72C延伸2min。首輪循環(huán)前94C預(yù)變性4min,最后1個循環(huán)后在72C下延伸5min,產(chǎn)物置于4C條件下保存。瓊脂糖凝膠電泳。將擴增產(chǎn)物在1.5%瓊脂糖凝膠上進行電泳，恒壓85V電泳50~75min,使用凝膠成像分析儀檢測并拍照。數(shù)據(jù)統(tǒng)計與分析多態(tài)位點比例。統(tǒng)計時僅記錄清晰、穩(wěn)定的電泳帶,統(tǒng)計位點總數(shù)、多態(tài)位點數(shù)，然后按照以下計算公式計算多態(tài)位點的比例(P):P=某群體多態(tài)位點數(shù)/位點總數(shù)X100%。聚類分析。根據(jù)瓊脂糖凝膠電泳結(jié)果，利用GelComparH4.0數(shù)據(jù)處理系統(tǒng)軟件，應(yīng)用UPGMA法進行系統(tǒng)聚類分析。Barracudacaudalfinrayasmaterials,usingthephenol-chloroformextractiontoextractgenomicDNA,in4Cavoidlightpreservationundertheconditionofstandby,primerandreactionconditions.RAPDreactionsystemfor30mu1always,contains10xBuffer3mu1,dNTP(thetendencyfor2.51)0.4u1,Primer100mu(mol/1)0.24u1,TaqDNApolymerase(5u/mu1)0.3mu,templateDNA0.3mug1.RAPDreactionprocessincluding35cycle:94Cmodified1min,36Cannealing1min,72Cfor2min.Firstroundloopbefore94C4min,1lastcycleextensionunder72°Cafter5min,productunder4°Cundertheconditionofpreservation.Agarosegelelectrophoresis.Amplificationproductson1.5%agarosegelelectrophoresis,theelectrophoresis50constantvoltage85v~85min,gelimaginganalyzerwereusedtodetectandtakepictures.Datastatisticsandanalysisoftheproportionofpolymorphicloci.Statisticswhentherecordisclear,stableelectrophoresisband,statisticaltotalnumberofloci,theNumbersofpolymorphicsites,andthencalculatedaccordingtothefollowingformulatocalculatetheproportionofpolymorphicloci(P):P=agroup100%(totalNumbersofpolymorphicsites/locations.Clusteranalysis.Accordingtotheresultsofagarosegelelectrophoresis,usingGelComparII4.0dataprocessingsystemsoftware,thesystemclusteranalysisusingUPGMAmethod.20個引物共擴增出4293條清晰的條帶，其中擴增片段長度大多在400~3000bp,其中養(yǎng)殖群體共擴增出2084條,自然群體共擴增出2199條。其中，列出了引物S76分別對梭魚養(yǎng)殖群體和自然群體的各20個個體的擴增產(chǎn)物的電泳結(jié)果，所有篩選出來的20個RAPD引物對梭魚2個群體的檢測結(jié)果?？梢钥闯?，自然群體共檢出了204個擴增位點,其中有136個表現(xiàn)出多態(tài)，多態(tài)位點比例為66.7%;在養(yǎng)殖群體中，共檢出了217個擴增位點,其中有130個表現(xiàn)出多態(tài)，多態(tài)位點比例為59.9%。聚類分析基于Nei氏遺傳距離，采用UPGMA方法構(gòu)建各群體的親緣關(guān)系樹狀圖。從圖2可以看出,40個個體分為兩大類群，其中15個養(yǎng)殖個體聚為1個類群，另1個類群分別由20個自然個體和5個養(yǎng)殖個體組成。Article20primersamplifiedout4293clearbands,includingmostofamplificationfragmentlengthin400~3000bp,includingbreedingpopulationwereamplifiedfrom2084,thenaturalpopulationwereamplifiedfrom2199.WhichliststheprimerS76respectivelythemulletbreedinggroupandnaturalgroup20individualamplificationelectrophoresisresults,productsofallscreeningout20RAPDprimertobarracudatwogroupsoftestresults.Itcanbeseenthatnaturalpopulation204amplifiedlociweredetected,amongthemthereare136showedpolymorphism,proportionofpolymorphiclociis66.7%;Infarmingcommunities,217amplifiedlociweredetected,amongthemthereare130showedpolymorphic,thepercentageofpolymorphiclociwas59.9%.ClusteranalysisbasedontheNei'sgeneticdistance,UPGMAmethodwasusedtoconstructgeneticrelationshiptreeofeachgroup.Canbeseenfromfigure2,40individualsaredividedintotwogroups,15breedingindividualsgatheredforagroup,theotheronegroupsrespectivelyby20individualnatureandfivebreeding.根據(jù)筆者測定的梭魚的多態(tài)位點比例與稀有嗣鯽、真鯛等其他魚類的多態(tài)位點比例分析它們的遺傳多樣性:梭魚的遺傳多樣性最為豐富，依次為真鯛、稀有嗣鯽、唐魚、牙鲆、艦狀黃姑魚。孟憲紅等認為真鯛較高的遺傳變異度與真鯛生命周期較長、野生群體年齡組成復(fù)雜有關(guān);唐魚與稀有嗣鯽均屬于分布區(qū)較窄、生境狹小的低等鯉科魚類，遺傳多樣性相似;牙鲆較低的遺傳多樣性水平可能是因為其為冷水性底層魚類，洄游距離短,不同地理群體難以遠交。此外，蒙子寧在研究小黃魚遺傳多樣性時也發(fā)現(xiàn)小黃魚較高的多態(tài)位點比例可能與小黃魚的廣分布性及其棲息地多樣性有關(guān)。魚類的遺傳多樣性還與該物種是否歷經(jīng)人工養(yǎng)殖或種苗放流增殖有關(guān),其過程往往會因遺行車配件傳漂變和近交等因素而造成種群遺傳多樣性降低。在以上用于比較的魚類中，梭魚的遺傳多樣性最高,艦狀黃姑魚最低就是最直接的例證。權(quán)潔霞等認為黃河口海域梭魚人工養(yǎng)殖群體的遺傳多樣性并沒有顯著降低，而且與自然群體之間無明顯的遺傳分化，其可能與粗放式人工養(yǎng)殖且人為干涉因素較少有關(guān)。楊銳等也認為梭魚養(yǎng)殖群體與自然群體并無明顯的遺傳分化，這可能是因為梭魚人工養(yǎng)殖比較粗放，塑料土工格柵養(yǎng)殖歷史較短（連續(xù)繁殖2~3代），繁殖過程中親魚多直接采自自然群體，少有定向選擇與近親繁殖所致。該試驗結(jié)果表明梭魚養(yǎng)殖群體與自然群體的結(jié)構(gòu)差異也并不明顯，泰山奇石與前人的研究結(jié)果相一致。由此可見，目前的梭魚人工養(yǎng)殖業(yè)的技術(shù)與經(jīng)驗是較為合理的，具有較好的發(fā)展前景。梭魚種質(zhì)資源的保護梭魚是近年來發(fā)展非常迅速的水產(chǎn)養(yǎng)殖對象之一，人工養(yǎng)殖業(yè)的規(guī)模不斷擴大。盡管該試驗中人工養(yǎng)殖梭魚遺傳多樣性較高，但是與權(quán)潔霞的研究結(jié)果相比，其多態(tài)位點比例已經(jīng)降低了約20%,遺傳多樣性有了明顯的下降。因此,在養(yǎng)殖生產(chǎn)中，必須采取有效措施，以保護梭魚優(yōu)良的遺傳種質(zhì)資源。親魚必須要選取遺傳多樣性豐富的群體，并且要以自然群體的遺傳多樣性分析作為依據(jù)；還應(yīng)該注意保護親魚的有效群體，避免近親繁殖，在生產(chǎn)中進行科學(xué)管理,使梭魚種質(zhì)資源得到可持續(xù)開發(fā)與利用。鍋爐配件AccordingtotheauthordeterminetheproportionofpolymorphiclociandbarracudarareJucarp,redporgyandotherfish,theproportionofpolymorphiclocianalysisoftheirgeneticdiversity,geneticdiversityofbarracudathemostabundant,followedbyredporgy,rareJucarp[15],tangfish,gram-negative,Mianspottedmaigre[16][17].MengXiangongthinkredporgysuchashighdegreeofgeneticvariationandredporgywithalongcyclelife,wildpopulationagecompositioncomplex;TangfishandrareJucarpallbelongtothearearelativelynarrow,lowhabitatsmallfishesofcyprinidae,similartogeneticdiversity;WereatalowlevelofgeneticdiversitymaybebecauseitisLengShuiXingbottomfish,shortmigrationdistance,differentgeographicpopulationduetofar.Moreover,ning[18]inthesmallyellowcroakergeneticdiversityisalsofoundthatsmallyellowcroakerishigherpercentageofpolymorphiclocimaybeassociatedwiththewidedistributionandhabitatdiversityofsmallyellowcroaker.Fishofgeneticdiversityandthespeciesisalsothroughartificialcultivationorseeddischargeproliferationisrelatedtotheprocesstendtobecausedbyfactorssuchasgeneticdriftandinbreedingpopulationgeneticdiversity.Intheaboveusedtocomparefish,barracudathehighestgeneticdiversity,Mianspottedmaigrelowestisthemostdirectexample.QuanJieXia[19]thinkbarracudariverestuarywaterssuchaspopulationgeneticdiversityoffarmeddidnotsignificantlyreduce,andwithnoobviousgeneticdifferentiationbetweennaturalgroup,itmaybeassociatedwithlessextensiveartificialbreedingandartificialinterferencefactors.YangRui[14]alsothinkbarracudabreedinggroupandnaturalgroupnoobviousgeneticdifferentiation,itmaybethatthebarracudafarmedmoreextensive,shortbreedinghistory(for2~3generationsofbreeding),intheprocessofbreedingmothermoredirectlyfromthenaturalpopulation,causedbyararedirectionalselectionandinbreeding.Theexperimentresultsshowthatthestructureofmulletbreedinggroupandnaturalgroupdifferencesarenotobvious,alsoconsistentwithpreviousresearchresults.Thus,thepresentbarracudaartificialbreedingtechnologyandexperienceismorereasonableandhasgoodprospectsfordevelopment.Barracudagermplasmresourcesprotectionbarracudaisdevelopingveryrapidlyinrecentyears,aquacultureobject,oneofartificialbreedin