Whole body samples were homogenized in 1ml of Trizol per 50-100 mg of tissue to isolate total RNA. Polyadenylated mRNA was then isolated from 20ug total RNA using an mRNA Purification Kit (Invitrogen). Double-stranded cDNA was made using Superscript Double-Stranded cDNA Synthesis Kit (Invitrogen) and random hexamer primers. Size fractionated 200-400bp cDNAs were used for Solexa library construction (paired end layout).