Home G418, Geneticin百款热销好货限时特促！猛戳 ››G418, Geneticin展开导航 筛选抗生素G418, Geneticin Zeocin 嘌呤霉素 Blasticidin Hygromycin B Commonly know as G418 or G-418, Gibco Geneticin reagent is an aminoglycoside related to gentamicin, and is commonly used as a selective agent for eukaryotic cells. As an analog of neomycin sulfate, it interferes with the function of 80S ribosomes and protein synthesis in eukaryotic cells.The dominant-acting resistance genes (neor) used on common mammalian expression vectors contain elements derived from either transposons Tn601 (903) or Tn5. When grown in medium containing Geneticin selection agent, stable colonies of mammalian cells expressing these resistance markers can be generated in 10 to 14 days.10131035,10131027,11811023,11811031,11811098 What\'s in your G-418? To be effective, selection agents need to be reliable, highly pure, and consistent in nature. Geneticin selective antibiotic, considered the gold standard for nearly two decades, is the only G-418 reagent that delivers these qualities to your mammalian cell cultures.Compared to other manufacturers’ G-418 products, Geneticin antibiotic exhibits higher purity, so you can use less and produce greater selection pressure with minimal toxicity from contaminants. When evaluating G-418 products, consider more than just potency. Look at purity and working range. Taken together, these three characteristics provide a true evaluation of the effectiveness of your G-418.PurityPotencyED50 AssayPurity. The purity of Geneticin selection agent is consistently greater than 90%, as determined by HPLC — far higher than any other supplier. This means:15-30% lower concentrations of Geneticin agent can be used, as compared to other G-418 products, to achieve comparable selection results.Surviving clonal colonies may arise faster, and cells may appear healthier when using Geneticin instead of lower purity G-418 products.Potency. Potency as a descriptive term is often used synonymously with purity, but potency as reported in QC data is actually not related to purity. The potency value is a measure of bacterial growth inhibition. Gentamicins that commonly contaminate G-418 preparations from other suppliers will add to potency in bacterial assays yet have no effect on mammalian cell selectivity. Other bacterial contaminants in impure G-418 may be toxic to mammalian cells, consequently lowering the ED 50 value.Therefore, comparing potency values between different suppliers is not a relevant specification for mammalian cell selection.ED50 Assay.This is a true measure of eukaryotic growth selectivity as determined on reference NIH3T3 cells. Higher purity generally translates to higher ED50 values.Toxic impurities lower the ED50 value, which means a more narrow working range of antibiotic selection.A consistent ED50 from a supplier assures performance reproducibility from lot-to-lot in mammalian cell culture applications. This means when purchasing a new lot of Geneticin, you do not need to re-optimize for ideal antibiotic concentration (assuming that no other media alterations). The wide ranges of ED50 displayed in different lots from alternative G-418 suppliers may require you to re-optimize for each lot. Lot-to-lot consistency with Geneticin is sufficiently high that you will not notice any difference in selection performance between lots. Purity Purity. The purity of Geneticin selection agent is consistently greater than 90%, as determined by HPLC — far higher than any other supplier. This means:15-30% lower concentrations of Geneticin agent can be used, as compared to other G-418 products, to achieve comparable selection results.Surviving clonal colonies may arise faster, and cells may appear healthier when using Geneticin instead of lower purity G-418 products. Potency Potency. Potency as a descriptive term is often used synonymously with purity, but potency as reported in QC data is actually not related to purity. The potency value is a measure of bacterial growth inhibition. Gentamicins that commonly contaminate G-418 preparations from other suppliers will add to potency in bacterial assays yet have no effect on mammalian cell selectivity. Other bacterial contaminants in impure G-418 may be toxic to mammalian cells, consequently lowering the ED 50 value.Therefore, comparing potency values between different suppliers is not a relevant specification for mammalian cell selection. ED50 Assay ED50 Assay.This is a true measure of eukaryotic growth selectivity as determined on reference NIH3T3 cells. Higher purity generally translates to higher ED50 values.Toxic impurities lower the ED50 value, which means a more narrow working range of antibiotic selection.A consistent ED50 from a supplier assures performance reproducibility from lot-to-lot in mammalian cell culture applications. This means when purchasing a new lot of Geneticin, you do not need to re-optimize for ideal antibiotic concentration (assuming that no other media alterations). The wide ranges of ED50 displayed in different lots from alternative G-418 suppliers may require you to re-optimize for each lot. Lot-to-lot consistency with Geneticin is sufficiently high that you will not notice any difference in selection performance between lots.Table 1. Comparison of Geneticin specifications with alternative G-418 suppliers.SpecificationInvitrogenSupplier ASupplier BThe Geneticin AdvantagePurity (HPLC) 90-93%66-75%65-82%Significantly higher purityPotency claimed (µg/mg)718-735712-724673-735More stringent potency assayPotency upon retest (µg/mg)718-735640-659621-677Consistently higher actual potencyED50 Assay (µg/ml)2450-27001350-3100600-2350Reliable selection lot-to-lotTable 1. Multiple lots of G-418 from two different suppliers were analyzed according to Invitrogen raw material QC protocols for Geneti. It was observed that results obtained with G-418 from Supplier A and Supplier B displayed wide variations on all measured parameters, including an inconsistency between the actual potency and the value reported on the supplied product literature. Discrepancies between re-tested potency values and that claimed by other suppliers may be due to differences in G-418 reference lots and assay procedures. Figure 1. Geneticin displays greater purity than G-418 from alternative suppliers. Figure 1. Comparison of HPLC data of Geneticin with selected lots of G-418 from Supplier A and Supplier B. Samples were prepared and analyzed according to the procedure published in Clinical Chem. (1978), Vol. 24, No.11, p1940.