Figure 4. Expression of C. elegans miRNAs during larval development. Total RNA was analyzed from mixed-stage N2 worms (M), embryos (E), larval stages (L1, L2, L3, L4), adults (A),
glp-4(
bn2) adults (G), N2 dauers (D), mixed-stage
him-8(
e1489) worms (H), and N2 starvation-arrested L1 larvae (sL1). Intense signals are represented as black rectangles and faint signals are represented as gray rectangles. Of the 87 C. elegans miRNAs identified, 6 could not be detected on developmental Northerns (miR-41, miR-78, miR-249, miR-253, miR-254, and miR-255). (A) miRNAs constitutively expressed throughout nematode development. (B) stRNAs,
lin-4 and
let-7, and similarly expressed miRNAs, which commence expression during larval development and remain expressed through adulthood. (C) miRNAs with discontinuous developmental expression patterns. (D) Northern analysis of miRNAs with enhanced expression in the dauer stage. To control for loading, the blot used for both miR-234 and miR-248 and the blot used for miR-247 were reprobed for the U6 snRNA (U6). Quantitation with a PhosphorImager showed that the lane-to-lane variation in U6 signal was as great as threefold. Normalizing to the U6 signal, the miR-248 signal was fourfold greater in dauer than in most other stages, except for
glp-4 adults, in which it was twofold greater, whereas the miR-234 signal was highest in dauer and L1, with a signal in these stages about twofold greater than the average of the other stages. (E) Northern analysis of the
lin-4 RNA and its paralog, miR-237.