Fig. 3. Twenty-five genes with known expression patterns are detected. (A) Gene expression profiles for 10 embryonic transcription factors characterized by specific developmental phenotypes resulting from disruption of their function. Transcript abundance is plotted on a log2 scale. The key includes in parentheses the approximate number of cells (out of 102) in which each gene is expressed at 140 minutes. The maternal expression of lin-26 and early transient induction of hlh-1 are both consistent with reported expression patterns (Krause et al., 1990; Quintin et al., 2001). (B) Gene expression profiles for seven maternally expressed genes previously characterized as Class I (stable everywhere) by virtue of their in situ hybridization patterns (Seydoux and Fire, 1994). (C) Gene expression profiles for eight maternally expressed genes previously characterized as Class II (degraded in somatic blastomeres, stable in germline precursors) by virtue of their in situ hybridization patterns (Seydoux and Fire, 1994).