Here, in the interests of ‘if you have to email it twice, write a blog’ is my high-level overview of what a bacterial genomics pipeline looks like. 1. quality assess fastqs with e.g. fastqc, visualise these across your dataset with MultiQC. If data is particularly bad, do quality trimming, if not, then don’t. 2. do species…
This post belongs in the ‘write it down before you forget’ category. Edit – this approach is necessary for handling the trees produced by RAxML, but not those produced by IQ-TREE. Edit #2 – Ancestral state reconstruction in RAxML does not seem to work very well. I’m trying IQ-TREE (v1.6) instead. I have a tree…
Adapted by Lauren Cowley from original PHE training material by Philip Ashton and Tim Dallman Answers at the end Salmonella Enteritidis PT14b outbreak exercise Bioinformatics training, interpretation of phylogenies Prepared by the Gastrointestinal, Emerging and Zoonotic Infections department and the Gastrointestinal Bacteria Reference Unit, Public Health England, Colindale, London. Aim of Session To develop…
As a promethion looks comparable in startup cost with a MiSeq (though, actually, because the machine is free, you get more sequencing for your buck with the promethion), I wonder how much it would cost to sequence a bacterial genome on the promethion? This post involves a bunch of guesswork, extrapolation and the backs of envelopes,…
Quality Assessment and Trimming Trimmomatic http://www.usadellab.org/cms/index.php?page=trimmomatic Trimmomatic: A flexible trimmer for Illumina Sequence Data. Bolger, A. M., Lohse, M., & Usadel, B. (2014). Bioinformatics, btu170. A flexible read trimming tool that will remove Illumina adapters, reads below a certain length and low quality ends of the read Seqtk https://github.com/lh3/seqtk Tool for processing sequences in the FASTA…
I have recently started using the high performance cluster at the Sanger Institute, and it comes with an interesting quandary. You have to be explicit in the amount of RAM you request when you submit your job (the PHE cluster wasn’t like this). Then, that amount of RAM is assigned to your job and wont…
Travis Oliphant, who is involved with the really useful conda project, recently tweeted about David Beazley’s talk at pycon in chicago. Here’s the link to the whole thing, which is definitely worth watching. There are a few great tips in there, all around the idea that you only have to use python built-ins to do cool…
My wonderful soon-to-be-wife just had her PhD viva and we were struck by the similarity between PhDs and Frodo’s journey in the Lord of the Rings. Turns out this guy got there first, but I think our theory still brings something to the table. The main parallel is that there are, like, a million endings!!!…
The other day at PHE we were investigating use of MASH sketches to find closest isolates. If you don’t already know about MASH, it’s a MinHash algorithm implemented by Adam Phillippy’s group (@aphillippy). It is fast and pretty neat, but the resulting distance is directly related to the errors in the sequencing. On one hand,…
Kat Holt’s lab have a nice set of scripts that wrap around ete2 which makes it nice ‘n’ easy to annotate trees – plotTree! It works out the box! They have some great installation and usage instructions on the github, and some examples for the R half of the code, but the examples for the python bit are…
Bits and Bugs 