An Opinionated Bioinformatics Manual that Also Teaches You How to Do Experiments

A twitter discussion got us curious about the manual of the MIRA assembler and we found it exactly as promised. The author did a lot of work on helping researchers do their experiments properly to get high-quality assembly. Bioinformatics does not work without the ‘bio’ part done well, and bioinformatics programs cannot cause miracles, when the underlying data are of bad quality.

Here are two examples out of many informative sections -

Warning

For de-novo assemblies, do NOT (never ever at all and under no circumstances) use the Nextera kit, take TruSeq. The non-random fragmentation behaviour of Nextera leads to all sorts of problems for assemblers (not only MIRA) which try to use kmer frequencies as a criterion for repetitiveness of a given sequence.

13.6.1. Do not sample DNA from bacteria in exponential growth phase!

The reason is simple: some bacteria grow so fast that they start replicating themselves even before having finished the first replication cycle. This leads to more DNA around the origin of replication being present in cells, which in turn fools assemblers and mappers into believing that those areas are either repeats or that there are copy number changes.

Sample. In. Stationary. Phase!

For de-novo assemblies, MIRA will warn you if it detects data which points at exponential phase. In mapping assemblies, look at the coverage profile of your genome: if you see a smile shape (or V shape), you have a problem.

This is undoubtedly the most informative bioinformatics manual we came across, and is way better than many actual papers.