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简介：C3d是补体C3不可再被酶解的最小片段,在抗原特异性免疫建立之前,C3d可识别非己抗原并与之共价结合,增强了抗原递呈细胞的递呈能力、降低了B细胞的活化阈、提高特异性抗体的滴度、促进抗体亲和力成熟等.近年来研究显示,C3d还可以促进抗原特异性细胞免疫应答水平并改变机体免疫应答模式.所以,C3d是连接固有性免疫和获得性免疫的桥梁.本文对C3d的分子生物学特征、生物学功能以及作为分子佐剂可能的分子机制进行了简要总结.

简介：CellsregulatephospholipaseD(PLD)activityinresponsetonumerousextracellularsignals.Here,weinvestigatedtheinvolvementofPLDactivityintransforminggrowthfactor-β(TGF-β1)-mediatedgrowthinhibitionofepithelialcells.TGF-β1)-mediatedgrowthinhibitionofepithelialcells.TGF-β1inhibitsthegrowthofMDCK,Mv1Lu,andA-549cells.Inthepresenceof0.4%butanol,TGF-β1inducesanincreaseintheformationofphosphatidylbutanol,auniqueproductcatalyzedbyPLD.TGF-β1alsoinducesanincreaseinphosphatidicacid(PA)levelinA-549andMDCKcells.TGF-β1inducesanincreaseinthelevelsofDAGlabeledwith[^3H]-myristicacidinA-549andMDCKcellsbutnotinMv1Lucells.NoincreaseofDAGwasobservedincellsprelabeledwith[^3H]-arachidonicacid.ThedatapresentedsuggestthatPLDactivationisinvolvedintheTGF-β1-inducedcellgrowthinhibition.

简介：利用重叠延伸PCR法对扩展青霉碱性脂肪酶(PEL)基因进行体外定点突变,并构建了含突变基因的重组质粒pPIC3.5K-lip-D92P.将该质粒在毕赤酵母GS115菌株中表达.与野生型表达产物PEL-GS相比较,突变体表达产物PEL-D92P-GS最适作用温度为45℃,比野生型提高了5℃;其热稳定性与野生型相当;突变体在40℃下的表达量为109U/mL,约为野生型的29%.结果分析表明,Pro替代Asp92后,可能是由于Pro一级结构的特点,使酶结构更加稳定,在高温下更适于与底物结合.

简介：应用DNA聚合酶链式反应(PCR)技术,对p16抑癌基因(CDKN2)进行体外定点突变,在p16cDNA中引入第48位密码子CCG(Pro)→CTG(Leu)和第74位密码子GAC(Asp)→AAC(Asn)突变,构建了p16-P48L和p16-D74N突变体。野生型和突变型p16cDNA克隆于pcDNA3构建pCMV-p16、pCMV-p16P48L和pCMV-p16D74N真核表达载体,导入纯合缺失p16基因的人肺癌细胞株H460,经RNA点杂交、RNA印迹和细胞免疫化学染色,检测到P16表达。通过比较表达野生型和突变型P16的H460细胞在~3H-TdR掺入及细胞所在周期的差异,证实P16表达抑制细胞进入S期,而P48L和D74N突变体对细胞进入S期没有什么影响,提示P48L和D74N突变导致P16蛋白功能丧失。

简介：Fische：344大鼠在国外广泛应用于肿癌研究与慢性毒性试验，八十年代中期引入我国。我们对F344／K—Smu—D大鼠的生长发育的若干生物学特性进行了检测。结果表明，该品系大鼠体型较SD大鼠与Wistar大鼠小。除睾丸，垂体、肾上腺，乳腺外的大部分器官与组织的自发性肿瘤的发生率相对较低；将F344／K—Smu—D大鼠种群与F344／DuCrj种群比较，在体重、耗食量，血液学与生化学等方面的若干特性差异较大，肿瘤发生率与死亡差别不大。

简介：Amurinemacrophage-likecelllineJ774,acquired,inresponsetoLPS,anabilitytokilltumornecrosisfactor(TNF)-insensitivetargetP815mastocytomacellswhereasanothercellline,P388D1didnot,LPStriggeredsignalingmechanismsbetweenthetwocelllineswerecomparedwithanaimtoinquireaboutthepossiblenatureoftheabove-mentioneddifference,TheresultswhowedthattwocelllinesrespondtoLPS-treatmentbyparallelactivationofbothphospholipasesCandA2(PLCandPLA2)toapproximatelythesameextent.ThemaximumresponseoftothenzymesofJ774cellswasnotedwithin10minthetreatmentwhereasthatofP388D1cellsrequiredmorethan20min,TheotherpropertiesofLPS-responsiveenzymesstudiedweresimilarbetweentwocelllines,includingActivationofPLCandPLA2andPKCinmacrophagesbyLPS.Ca2+augmentationofenzymeactivation,participationofguaninenucleotidebinding(G)proteinsintheinitialactivationpreocesses,andinhibitionofenzymeactivationbythepriortreatmentofcellswithcholeraorpertussistoxinsetc.Moreover,LPS-triggeredactivationofPLCandPLA2wasfoundtobefollowedbytheincreaseofPKCactivitiesinbothcelllines.Inspiteofthesesimilarities.J774cellspossessedbothbasicandacidicformsofPKCactivities,whileP388D1cellsownedonlyPKCofbasicform,Nevertheless,thequestionwhyJ774cellsbutnotP388D1cells,canacquirethetumoricidalactivity,aganistP815,cellsfollowingLPStreatmentrematinstobeanswered.

简介：Amurinemacrophage-likecellline,J774,acquried,inresponsetoLPS,anabilitytokilltumornecrosisfactor（TNF）-insensitivetargetP815mastocytomacells,whereasanothercellline,P388D1,didnot.LPS-triggeredsignalingmechanismsbetweenthetwocelllineswerecomparedwithanaimtoinquireaboutthepossiblenatureoftheabove-mentioneddifference.TheresultsshowedthattwocelllinesrespondtoLPS-treatmentbyparallelactivationofbothphospholipasesCandA2（PLCandPLA2）toapproximatelythesameextent.ThemaximumresponseofbothenzymesofJ774cellswasnotedwithin10minofthetreatment,whereasthatofP388D1cellsrequiredmorethan20min.TheotherpropertiesofLPS-responsiveenzymesstudiedweresimilarbetweentwocelllines,ineludingActivationofPLCandPLA2andPKCinmacrophagesbyLPSCa2+augmentationofenzymeactivation,participationofguaninenucleotidebinding（G）proteinsintheinitialactivationprocesses,andinhibitionofenzymeactivationbythepriortreatmentofcellswithcholeraorpartussistoxinsetc.Moreover,LPS-triggeredactivationofPLCandPLA2wasfoundtobefollowedbytheincreaseofPKCactivitiesinbothcelllines.Inspiteofthesesimilarities,J774cellspossessedbothbasicandacidicformsofPKCactivities,whileP388D1cellsownedonlyPKCofbasicform.Nevertheless,thequestionwhyJ774cells,butnotP388D1cells,canacquirethetumoricidalactiyity,aganistP815cellsfollowingLPS-treatmentremainstobeanswered.