Expression data from silkworm posterior silk glands at the late larval stages

The silkworm silk gland is one of the most efficient protein synthesis systems among all organisms. Its amazingly efficient protein synthesis makes the silk gland a desirable object for basic studies on gene expression and regulation and for biotechnological applications. At the early stages of the fifth (final) instar, the cellular structures necessary for the synthesis of fibroin are rapidly formed, and at the later stage the synthesis of fibroin proceeds at a maximum rate. The posterior silk gland (PSG) is the longest suborgan and is responsible for the synthesis of the silk core protein fibroin, which is composed of heavy (H) and light (L) chains plus P25. We used microarrays to detail the global programme of gene expression in silkworm PSG during the late larval stages, including the fourth molting (M4) and day 1 (V1), day 3 (V3), day 5 (V5), and day 7 (wandering stage, W) of the fifth instar, and to reveal the correlations of differential expression genes with the PSG development and fibroin synthesis. Silkworm PSGs were collected at M4, V1, V3, V5, and W stages for RNA extraction and hybridization on 23K Silkworm Genome Arrays (CapitalBio Corp., Beijing, China). Three groups of biological replicates were prepared at each time point.Dual-dye experiments were performed for the PSG at M4, V1, V3, V5, and W; a total of 15 samples were tested including three biological replicates at each stage. Aliquots of each test sample were pooled as a common reference sample (CKA). The test samples and CKA were labeled with Cy3 and Cy5, respectively.