Only strains with sufficient reads to estimate fitness are shown,
but the strain fitness values are still rather noisy and may be biased towards zero.
Strains near the edge of a gene are not shown as being associated with that
gene (they are in grey).
Strains in the central 10-90% of a gene are color coded by the insertion's strand.
Usually, "+" means that the selectable marker is encoded on the forward strand,
i.e., transcribed rightward.