Inactivation of
sel-1 by RNAi had no impact on the viability of wild-type animals and only modestly reduced the viability of
xbp-1 mutants. However, when combined with inactivation of
abu-1,
sel-1(RNAi) increased lethality of
xbp-1 mutant animals. Combined inactivation of
sel-1 and
abu-1 also affected the appearance of
xbp-1 mutant animals. Viewed under Nomarski optics, the intestine of wild-type,
xbp-1 mutant,
abu-1(RNAi), or
sel-1(RNAi) young adults had a similar, fine, granular appearance. Animals with compound
xbp-1;
abu-1(RNAi) or
xbp-1;
sel-1(RNAi) genotypes had more dark staining large intestinal granules. The
xbp-1;
abu-1(RNAi);
sel-1(RNAi) animal had a marked increase in such granules. These observations suggest that
abu-1 (and possibly other abu genes) and
sel-1 perform partially redundant functions in animals with a blocked UPR.