Summary of microarray analysis and results. (A) Experimental design of the microarray experiments included four biological replicates from both the inbred (L5M4, 2, 6 and 5) and the original parental line (OHB4, 3, 6 and 5). RNA from each replicate sample was fluorescently labeled and hybridized to a custom microarray containing probes for 15,220 Heterorhabditis bacteriophora transcripts identified in an EST library. Statistical analysis of microarray data identified 1,185 transcripts with significant (p < 0.05) differential expression between the two lines. (B) Clustergram of the profiles of the 1,185 differentially expressed transcripts (rows) in the eight microarray experiments (columns). Higher expression levels, relative to the mean expression levels for a given transcript, are indicated by red features and lower expression levels are indicated in green. Differences in intensity reflect gradations of over- or under-expression. Transcripts were hierarchically clustered into those with similar profiles.