Man2, a1 and Ricin Resistance in ES Cells Figure 8. MALDI-TOF MS profiling of AB2.2, NN5 and F10 N-glycans (mz 3650–5000). The expanded region (m/z 3650–5000) is shown on the panels D, (AB2.2), E, (NN5) and F, (F10). N-glycans were permethylated prior being subjected to MS analysis and m/z values correspond to [M+Na]+ ions. Scheme assignments are based on the precise fit between composition calculations and the m/z (z = 1) ratio of the molecular ions detected. These schemes represent the most likely structures taking into account the biosynthetic pathways and the enzyme repertoire of murine cells and selected MS/MS analyses. Sugar symbols are those employed by the Consortium for Functional Glycomics. Circles represent hexoses (yellow: galactose, green: mannose), blue squares represent N-acetylglucosamine, red triangle: fucose, purple diamonds represent N-acetylneuraminic acid. doi:10.1371/journal.pone.0022993.g008 Genomic long range and triple primer PCR Genomic long range PCR (LR-PCR) was performed with primer pairs representing the genomic sequences flanking the PB gene-trap insertion (supplementary table S1). Using the recommended PCR conditions (Thermo), the PCR product of homozygous ES cell clones incorporates the 6.6 kb PB gene-trap cassette whilst heterozygous clones only have a small 428 bp genomic region. PLoS ONE | www.plosone.org 10 August 2011 | Volume 6 | Issue 8 | e22993