Shotgun metagenomic sequences of our mock community appear to be devoid of 16S chimeras, supporting a role for shotgun metagenomics in validating novel organisms discovered in targeted sequence surveys. Chimeras were found to reproducibly form among independent amplifications and contributed to false perceptions of sample diversity and the false identification of novel taxa, with less-abundant species exhibiting chimera rates exceeding 70%. By benchmarking CS performance against sequences derived from a controlled DNA mixture of known organisms and a simulated chimera set, we provide insights into the factors that affect chimera formation such as sequence abundance, the extent of similarity between 16S genes, and PCR conditions. CS detects chimeras with greater sensitivity than previous methods, performs well on short sequences such as those produced by the 454 Life Sciences (Roche) Genome Sequencer, and can scale to large data sets. We developed a new chimera detection tool called Chimera Slayer (CS). Chimeras are hybrid products between multiple parent sequences that can be falsely interpreted as novel organisms, thus inflating apparent diversity. Perceived diversity, however, can be influenced by sample preparation, primer selection, and formation of chimeric 16S amplification products. Bacterial diversity among environmental samples is commonly assessed with PCR-amplified 16S rRNA gene (16S) sequences.
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‘So who was responsible for this?’ They pondered, grey fingers brushing idley over the intricate designs that encrusted the cover of the book.įortunately, Core had a feeling they wouldn’t have to wait long to find out.Ī storyshift Chara wakes up in an Undertale Sans’s timeline with no recollection as to how she got there, and as the two race against the clock to get her back home, the rest of the multiverse Outcodes are left to discover just how deep this rabbit hole goes. After all, the mass assortment of AU’s that had caught their attention clearly wasn’t the doing of either Ink or Error, or any other outcode for that matter. It was hard to decipher who or what could have done this, or even what ‘this’ was. The child paused mid step, their non-Existent eyes wide with a mix of both wonder and fear as they looked at the mess before them.
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