David Coil edited 16S rDNA Sequencing and Analysis (Organism Identification).md  about 9 years ago

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After PCR is completed, confirm the PCR reaction worked by agarose gel electrophoresis, all controls behaved as expected (i.e. band in the positive control and no band in the negative control), and that you have DNA fragments of the correct size (~1350bp).   ##Submit Samples for Sequencing  Very few single-researcher labs currently have the capacity to do Sanger sequencing. However, there are a number of DNA sequencing facilities (commercial and academic) that provide Sanger sequencing services for researchers. They will handle as little as a single sample, or will allow you to submit an unlimited number of samples, typically arrayed in 96-well plates. You will typically provide both your PCR product as well as primers for sequencing (typically, the same primers used for PCR are used for sequencing). To get the most data, do not forget to request forward (_e.g_., using primer 27F) and reverse (_e.g._, using primer 1391R) reactions for each sample. Each facility will have its own guidelines concerning DNA and primer concentration. Our lab uses the [UC Davis Sequencing Facility](http://dnaseq.ucdavis.edu). If an internet search does not reveal the presence of a Sequencing Facility near you, most sequencing centers will allow you to ship samples to them for sequencing. Another possibility is Science Exchange ([Science Exchange](https://www.scienceexchange.com/) which is an online clearinghouse for lab services.  ##Sanger Sequence Processing  The end product of Sanger sequencing is the production of sequences (reads) for each sample submitted. Upon receiving Sanger reads from a sequencing facility, typically via e-mail, it is necessary to do some pre-processing before they can be analyzed. These steps include quality trimming the reads, reverse complementing the reverse sequence, aligning the reads, generating a consensus sequence, and converting to FASTA format. Note - there are dozens of different formats used for sequence information. FASTA format is one of the simplest. In the FASTA format a sequence file is given a name in one line (the name follows the character '>') and then the sequence information is in the following lines. There are very limited options for free software that allow the user to perform these steps.