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Percoll density gradient centrifugation1应用2Outline Principles Physical properties Storage Make and use density of Percoll Tips Protocol Instrument and operation References and applications Contrast(differential velocity centrifugation)2应用2 For biological particles,the ideal gradient medium has been described as one having the following characteristics:covers a sufficient density range for isopycnic banding of all biological particles of interest possesses physiological ionic strength and pH is iso-osmotic throughout the gradient has low viscosity is non-toxic will not penetrate biological membranes is supplied sterile and is resterilizable will form self-generated gradients by centrifugation at moderate g-forces is compatible with biological materials is easily removed from purified materials does not affect assay procedures will not quench radioactive assays3应用2Principles of density gradient centrifugation4应用2Separation by density(isopycnic centrifugation)Separation by size(rate zonal centrifugation)5应用2Percoll physical properties Percoll is available from GE Healthcare.Composition silica sol with nondialyzable polyvinylpyrrolidone(PVP)coating（由聚乙烯吡咯烷酮包裹的硅胶颗粒）Density 1.130 0.005 g/ml Conductivity 1.0 mS/cm（电导率）Osmolality 25 mOsm/kg H2O（渗透压）Viscosity 10 5 cP at 20C（粘度）pH 9.0 0.5 at 20C Refractive Index 1.3540 0.005 at 20C（折射率）Percoll is non-toxic1.01.3g/ml The viscosity of Percoll is lower in saline solutions atphysiological ionic6应用2Storage of Percoll Sterile and unopen-5 years When opened,Percoll should be stored below+8 If Percoll opened under non-sterile conditions,it can be frozen for up to 6minths at-18 Preformed gradients can be stored for weeks without a change in gradient shape,provided that the gradient is sterile and is not physically disturbed If stored at-18C,gradients form upon thawing,necessitating a mixing of the contents of the bottle before use.7应用2Sterilization of Percoll solutions 120C for 30 min Absence of salts or sucrose.Minimum contact with air(narrow-necked bottle)If Percoll form particles,these particles may be removed by low speed centrifugation.If any significant evaporation occurs during autoclaving,the volume should be replenished with sterile water so that the density is not affected.8应用2How to make and use gradients of PercollMaking and diluting a stock solution of PercollWhere Vx=volume of diluting medium(ml)Vo=volume of undiluted Percoll(ml)o=density of Percoll(1.130+0.005 g/ml*)10=density of 1.5 M NaCl=1.058 g/ml density of 2.5 M sucrose=1.316 g/ml i=density of SIP solution produced(g/ml)Thus,for SIP in saline,i=1.123 g/ml,for SIP in sucrose,i=1.149 g/ml,assuming o=1.130 g/ml.Adding 9 parts(v/v)of Percoll to 1 part(v/v)of 1.5 M NaCl or 10 concentrated cell culture medium is a simple way of preparing a Stock Isotonic Percoll(SIP)solution.“渗透活性物质的物质的量除以溶液的体积称为溶液的渗透浓度（osmolarity），单位为mol/L或mmol/L”9应用2How to make and use gradients of PercollDiluting stock solutions to lower densities Solutions of Stock Isotonic Percoll(SIP)are diluted to lower densities simply by adding 0.15 M NaCl(or normal strength cell culture medium)for cell work,or with 0.25 M sucrose when working with subcellular particles or viruses.10应用2Tips of making and use gradients of Percoll The colloid does not perceptibly diffuse over time,resulting in the formation of very stable gradients.Therefore,both discontinuous and continuous gradients can be prepared weeks in advance,giving great reproducibility over the course of an experiment.Measure the weight of the solution,make sure the weight of solution are all the same.实验重复性的保证Weight of Weight of PercollPercoll50%50%55%55%60%60%65%65%SIP-20170914SIP-20171014SIP-2017111411应用21.Percoll was diluted 9:1(vol/vol)with 1.5 M NaCl,2.Put 10 ml of the Percoll solution into 15-ml Corex tubes and centrifuged at 19,240 gav for 15 min at 20C.(swinging bucket rotor)3.Approximately 2 109 cells(200 OD600)were pelleted,resuspended in 1 ml Tris buffer,overlaid onto the preformed gradient,and centrifuged at 400 gav for 60 min.Isolation of quiescent and nonquiescent cells form yeast stationary-phase cultureAllen C.The Journal of cell biology.200612应用2Percoll gradient purification of spores Strains were grown overnight in YPD liquid medium.Cells were washed twice with ddH2O and diluted to a final cell density of OD600=0.5.Then,10 l of equal-volume mixed cells were spotted on V8 medium and incubated for seven days in the dark at room temperature.The entire mating patch was suspended in 60%Percoll(GE Health)in PBS with 0.1%Triton X100.After centrifugation at 10,000 X g for 30 mins in an SW41Ti ultracentrifuge rotor(Beckman-Coulter),a band of spores near the bottom of the Percoll gradient was recovered with a 1-ml tuberculin syringe and transferred into an Eppendorf tube.The total spore production was determined by multiplying the spore density,measured by hemocytometer,with the final volume.Christina M.Hull PLoS genetics.201513应用2Instrument and operation14应用2Instrument and operation15应用2Instrument and operation16应用2Instrument and operationdata export17应用2References and applications18应用2contrastdifferential velocity centrifugationdensity gradient centrifugationSeparation criteriaWeightDensityCentrifugal speedTwo or moreOnly oneSuitable materialsDifferences in densityDifferences in sedimentation coefficient19应用220应用2
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