1)Fixation: -Washanimalsfromanunstarvedplatewithbuffer.Washthemfreeofbacteriawithwater,leavingtheminwaterinamicrofugetubeonice. -Addcold2XMRWBtoafinalconcentrationof1Xand20%formaldehydetoafinalconcentrationof1-4%(totalvolumeusually1ml).Mixwell,freezeindryice/ethanol,meltonice,andincubateonicewithoccasionalagitationfor0.5hrtoovernight.Frozensamplesmaybeprocessedimmediatelyorstoredindefinitely. Notes:Methanolprecipitatesproteins,reducingdiffusionbeforecrosslinking.Spermidineandformaldehydetogethercrosslinkproteins.Formaldehydeconcentrationandfixationtimeareimportantandshouldbeoptimized;agoodplacetostartis1%for0.5hr;morefixationwillstabilizesomeantigensbutdestroyothers(likeunc-86).Freezingcrackseggshells,lettingthefixativesin. 2)Reduction: -WashwormstwicewithTrisTritonbuffer,thenincubateinTrisTritonbuffer+1%BME,1-2hoursat37degreeswithmildagitation.Afterthispointthewormsarefragileandshouldn"tbespunhard(5000rpminamicrofugeisOK).Note:SteveSalserreportsthatspinningthewormsisessentialfortheprotocoltowork;lettingthemsettleoutapparentlydoesnotprovideenoughstresstoopenthecuticle. -Washwormsoncein10-15vols.1xBO3buffer,thenincubatein1xBO3buffer+10mMDTT,15minwithagitation. Notes:BMEandDTTreducethedisulfidelinkagesthathelpholdthecuticletogether;Tritonkeepsthewormsfromstickingtoeachother.Thedisulfidereductioniscompleteinminutes;theextendedincubationat37degreesistokillwormenzymeslikeDNases,proteasesandperoxidases(whichwreakhavokintheoxidationstep). 3)Oxidation: -Washwormsoncein10-15vols.1xBO3buffer,thenincubatein1xBO3buffer+0.3%H2O2,15minatroomtemperature.AgitategentlybutkeeptubesuprightbecausethecapmaypopopenfromtheO2pressure. -Washoncewith1xBO3bufferandonceforatleast15minwithantibodybufferB.Storewormsat4degreesinantibodybufferA.Notes:H2O2oxidizesthe-SHgroupsto-SO3.Donotover-wash,sodisulfidesdonotreform.BO3bufferprovidesthebasicpHneededforthereaction.Cysteinesandmethioninesinotherproteinswillbeoxidizedaswell,possIBLyaffectingsomeepitopes.MetbutnotCyscanberestoredbyasecondDTTtreatment. 4)Staining: DoantibodyincubationsinbufferAandwashesinbufferB. Buffers: 2XModifiedRuvkun"switchesbrew(MRWB)160mMKCl40mMNaCl20mMNa2EGTA10mMSpermidineHCl30mMNaPIPESpH7.450%methanol TrisTritonbuffer100mMTrisClpH7.41%TritonX-100orNP-401mMEDTA 40xBO3buffer(pH~9.2at25mM)1MH3BO30.5MNaOH Antibodybuffers:A1XPBS1%BSA0.5%TritonX-100orNP-400.05%NaAzide1mMEDTA BSameasAexcept0.1%BSA 20%formaldehydeWeighsomewhatmoredryparaformaldehydethanyouneed(<300mg)andputitinamicrofugetube.Multiplytheweightinmgby4.5andaddthatvolumeinmicrolitersof5mMNaOH.Placein65degreebathfor30minuteswithoccasionalmixing.Spinfor1min.topelletundissolvedparaformaldehyde.Usethesupernatantimmediately.FixationandpermeABIlizationprotocol5/30/91MikeFinney
Thisprotocolworksforallstagesexceptdauers(whichwon"topen)andhypoclorite-treatedeggs(whichdisintegrate).Luckily,hypochloritetreatmentandfixationarebythemselvessufficienttoopeneggs.Thistechniqueshouldworkforvirtuallyallpolyclonalseramostmonoclonals,aslongasthemajorepitopesdonotdependondisulfidebonds.AnimalsfixedinthiswaycanbestainedwithX-gal.