Description
A microarray time series was generated to identify cyclic genes of the segmentation clock in the mouse. The right posterior half presomitic mesoderms (PSM) from 17 mouse embryos were dissected while the contralateral side of the embryo containing the left PSM was immediately fixed to be analyzed by in situ hybridization using a Lfng probe to order the samples along the segmentation clock oscillation cycle. Probes were produced from RNA extracted from the 17 dissected posterior half PSMs using a two-step amplification protocol and were hybridized to Affymetrix GeneChip MOE430A. The reproducibility of the amplification procedure was initially assessed by comparing array data generated from the right and the left posterior PSM from the same embryo. Because of the symmetry of the paraxial mesoderm along the left-right axis, left and right samples are expected to show overtly similar gene expression. RNA was amplified from three such sample pairs (1, a and b; 2, a and b; 3, a and b) and hybridized on Murine Genome U74Av2 array (MG-U74Av2)