Paris Postdoc Seminar – Katie Pelletier

Katie Pelletier (postdoc at the Institut de Biologie de l’École Normale Supérieure (IBENS)) will present a Paris Postdoc Seminar on the theme:

Changing developmental signal has an effect on developmental bias: Wnt mutation modifies phenotypic co-variation patterns for cell fates in the nematode vulva

Abstract:

While mutation is mostly random at the DNA level, realized co-variation between traits following random perturbation can be strongly biased along some directions of phenotypic space. Development is often invoked as an explanation as to why some combinations of trait values are more probable to co-occur than others. However, studies that modify the accessible phenotypic space though a manipulation of development are lacking. We use variation in cell fate of nematode vulva precursor cells to ask if reduction of morphogen signal is sufficient to change the co-variation pattern of these cells. Previous work in the lab has demonstrated that in Caenorhabditis, the most posterior cell, P3.p, is sensitive to random genetic perturbations while the fate of the next most anterior cell, P4.p, is not (Picao-Osorio et al 2025). Posteriorly expressed Wnt signal, encoded by two genes, egl-20 and cwn-1, is important for promoting the divided cell fate in Pn.p cells in C. elegans. We reduced the Wnt signal dose using a cwn-1 deletion and assayed the accessible phenotypic space of this mutant. The large-effect cwn-1 mutation results in a shift in the phenotypically accessible space, as P4.p becomes sensitive to random mutation, in contrast to P3.p being sensitive in the wild-type line. This is a direct example of how changes to a developmental signal can modify the realized co-variation of traits following perturbations.