Evidence for Proximal to Distal Appendage Amputation Site Effects from Global Gene Expression Correlations Found in Newt Microarrays

We have studied newt (N. viridescens) gene expression levels in ~ 1200 selected genes important in tissue regeneration at various times post-amputation at 6 different limb amputation sites. Here we provide analyses of microarray data that demonstrate a global gene expression correlation decrease on going from proximal to distal amputation sites of either limb or tail appendages. Also, the proximal (upper) forelimb and hindlimb regenerates have by far the most highly pairwise correlated gene expression levels of all sites. In contrast, the distal (lower) forelimb and hindlimb and tail regenerates reveal the least pairwise correlated gene expression levels. These data support the idea that limb loss at a proximal site produces afar more robust response as compared to a more distal site and requires a greater level of gene regulation to properly rebuild the lost structure.