Description
This column shows the gene expression data from the Rat Gene Expression
Atlas 2 from the Genomics Institute of the Novartis Research Foundation (GNF).
By default, the column shows the ratio of expression of a gene in a specific 
set of tissues to the expression of the gene overall. A gene that is more highly 
expressed in a tissue is colored red, and a less expressed gene is shown in 
green. The values are colored on a logarithmic scale. This coloring is standard, 
but is the opposite of what an inexperienced user 
might expect: in this case, red means go and green means stop!  
Black indicates that a gene is neither over- nor under-expressed in the tissue. 
Uncolored boxes (white on most browsers) represent missing data.  
Column Configuration
Several column configuration options are available on the Configuration page, 
which can be accessed via the configure button in the top menu.
- 
Absolute expression values: The display can be configured to show 
absolute expression values rather than ratio values. To toggle the display, 
select the absolute option from the values pulldown menu. 
Absolute expression values
are shown in shades of gray, with higher expression levels shown in lighter 
shades. As with ratio values, absolute values are colored on a logarithmic 
scale.
- 
Color scheme: Color-blind users can switch the coloring scheme from red/green to 
yellow/blue via the Expression ratio colors pulldown menu at the top
of the Configuration page.
- 
Level of tissue detail: The tissue pulldown menu
controls the amount and type of tissue data displayed. By default, only the 
median values for selected tissues are shown.  To display the value of all 
individual experimental replicates of all tissues, 
select the all replicates option. To view a single median value for each 
tissue, choose the median of replicates option.
- 
Brightness: To increase or decrease the brightness of the expression colors,
edit the number in the column's brightness text box. Values greater 
than 1.0 increase the brightness, while those less than 1.0 dim the color. 
Methods
Tissues for expression studies were collected from three albino out-bred 
strains of rat that are commonly used in studying human disease and physiology: 
Sprague Dawley, Wistar and Wistar Kyoto.  About 7000 characterized rat 
genes and 1000 EST clusters were examined in 11 peripheral and 15 brain 
regions.  For detailed information about the experiments, see 
  
 Walker, JR, Su, AI, Self, DW, Hogenesch, JB, Lapp, H, Maier, R, 
 Hoyer, D and Bilbe, G (2004). Applications of a Rat Multiple Tissue Gene 
 Expression Data Set. Genome Res. 14(4):742-749.
Credits
The data for this column was kindly provided by 
GNF
as part of the GNF Gene Expression Atlas.