Fig. 1.

Postembryonic development of C. elegans intestine: karyokinesis without cytokinesis during the L1 stage. (A) Differential interference contrast (DIC) and corresponding fluorescent images of early L1 larva with nuclei revealed by sur-5::GFP, which carries a nuclear localization sequence. A rectangle marks midintestinal cells that will become binucleate later during the L1 stage. (B) sur-5::GFP fluorescent images showing nuclei divisions and segregation within intestinal cells in late L1 larvae; dotted circles approximately show cell boundaries. Connected arrows point to recently divided cell nuclei. (C) DIC and fluorescent images of sur-5::GFP adult fed on E. coli from the time of hatching. (D) DIC and fluorescent images of a sur-5::GFP adult animal fed on Rhizobium from the time of hatching. Long and short arrows point to abnormally elongated and fragmented gut nuclei, respectively. On average, 78% of worms fed on Rhizobium have at least two instances of aberrant karyokinesis (elongated or fragmented nuclei or chromosomal bridges) whereas less than 10% have this phenotype on E. coli (n > 1,000).