this is what i do for a living. i will explain at length below. disclaimer: the following will likely bore some of you. others may enjoy it.
this is a heatmap of tissue-specific microarray probes i’ve found in the pacific salmon. each microarray probe corresponds to a gene (roughly), and through a fairly complicated process that i won’t explain here, the microarray probes allow a measure of gene expression in biological samples. you should think of the image as a matrix of data where numbers are represented as colors. each row corresponds to a single probe, and each column for a single tissue sample. (so the color at any given spot on the heatmap corresponds to the level of gene expression for that probe in that sample). bright yellow means lots of expression. the darker the yellow gets, the less expression there is.
you can see four main sort of divisions in the heatmap, these correspond, from left to right, to the brain, gill, liver, and muscle samples on the microarray.
the analysis of the genes corresponding to the probes on this heatmap will form the basis of a paper i am writing. no one has looked globally at gene expression in the pacific salmon before, so the paper will be useful for other people who want to study salmon in the pacific.
this was a fairly technical thing i’ve tried to explain here, so sorry if it makes no sense.