Figure 2.

lin-42(0) animals exhibit highly penetrant larval arrest and developmental delay phenotypes. (A) lin-42(0) mutants have a severe larval arrest phenotype. Individually plated wild-type, lin-42(n1089), lin-42(ok2385), and lin-42(ox461) mutants were monitored for developmental progression. The percentage of animals that arrested as larvae and failed to attain adulthood by 8 d posthatching is shown. n ≥ 100 for each genotype. (B) Micrographs of wild-type and lin-42(ox461) animals 72 hr posthatching. At this time point, all wild-type animals had reached adulthood and were laying eggs, whereas <2% of lin-42(0) mutants were adults, and they did not yet contain fertilized eggs, only oocytes. Most lin-42(0) animals appeared unable to complete the second larval molt. The left lin-42(0) panel contains two animals that are the same chronological age, with an inset showing the smaller animal is trapped in an unshed cuticle (white arrow). The right panel shows a 96 hr animal that appears arrested by size, but has nevertheless begun vulval morphogenesis, marked by the white v in inset. (C) Timing of molts in seven representative wild-type animals (top) and lin-42(0) mutants (bottom). Each horizontal row represents an individual animal that was monitored for pharyngeal pumping, lethargus, and ecdysis. Gray shading denotes animals in lethargus and vertical red lines indicate that a shed cuticle was observed on the plate. A total of 68 animals were followed for lin-42(ox461) and 10 for wild type. (D) The time of adult onset is delayed in lin-42 mutants. Animals from (A) that bypassed larval arrest were scored for the day posthatching that they reached adulthood, and graphed as percentage of animals that escaped arrest. n = 20, 125, 60, and 23 for wild type, n1089, ok2385, and ox461, respectively.