Fig. 2. efn-4 embryonic and larval phenotypes. Frames from 4D Nomarski DIC movies of individual embryos are shown; all embryos are shown as ventral views; times are relative to first cleavage and are the same for all genotypes. Scale bar: 20 µm in A-C; 50 µm in D-G. (A) Embryogenesis of wild type (N2), ventral views. Note complete closure of the ventral gastrulation cleft (outlined) by 280 minutes. (B,C) Frames from movies of two representative efn-4(bx80) embryos, showing enlarged ventral gastrulation clefts. A total of 58 efn-4(bx80) and 36 efn-4(e36) embryos were recorded for 4D analysis; the range and penetrance of phenotypes was similar in both mutants and the data are considered together below. Some phenotypes of efn-4 embryos could be classified using the same phenotypic classes as used to classify vab-1 and efn-1 phenotypes (George et al., 1998; Chin-Sang et al., 1999). Twenty percent (19/94) of efn-4 animals displayed the Class I phenotype shown in B, in which the gastrulation cleft was enlarged and persistent (dotted outline, 230-280 minutes), the epidermis failed to enclose and internal cells ruptured during early enclosure (330 minutes); this phenotype is seen in 19% of vab-1(0) animals and 12% of efn-1 animals. Three out of 94 animals exhibited a slightly weaker phenotype resembling the vab-1 Class II phenotype (enlarged gastrulation cleft; epidermis encloses, embryo turns then ruptures). One out of 94 efn-4 embryos displayed normal gastrulation clefts and arrested during elongation (vab-1 Class III phenotype), compared with 38% of vab-1 or 16% efn-1 embryos. Sixty-one out of 94 efn-4 embryos displayed the phenotype shown in C, in which the gastrulation cleft was transiently enlarged (230-280 minutes) and later closed; epidermal enclosure and elongation occurred with normal timing, and the embryo hatched with deformations in the posterior epidermis. Ten out of 94 embryos displayed wild-type development. (D-G) L1 larvae, showing wild type (D), efn-4(e36) mutant tail morphology (arrow, E,F) and efn-1(ju1) Notch head morphology (arrow, G).

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