Description

As part of our investigations of the interaction between C. elegans and D. coniospora, we made use of MosSCI strains, constructed in an unc-119(ed3) background (Frøkjær-Jensen et al., 2008; Maduro, 2015). We noticed that a variety of these strains exhibited a greatly increased susceptibility to infection. Upon further examination, we determined that this was due to an increase in the adhesion of fungal spores, most prominently at the tip of the head (Figure 1). The phenotype was not observed in a strain carrying a wild-type C. elegans unc-119 rescuing construct in an unc-119(e2498) background. But the increased spore adhesion was visible in both the unc-119(ed3) and the unc-119(tm4063) background even in the presence of the standard C. briggsae unc-119 rescuing construct. The phenotype was absent from these same transgenic strains in which unc-119(ed3) was eliminated by out-crossing (Table 1 below). unc-119 function has been extensively analysed in the nervous system. Notably, some expression in the epidermis was reported recently (Lear et al., 2018). While we have not determined the precise cause, since spore adhesion is a major determinant of infection progression (Zugasti et al., 2016), such effects need to be taken into account when interpreting experiments involving any strain that has an unc-119 allele in it, which has been often employed as selectable marker for transgenesis.