[
Dev Cell,
2017]
Single-cell measurements have broadened our understanding of heterogeneity in biology, yet have been limited to mostly observational studies of normal or globally perturbed systems. Typically, perturbations are utilized in an open-ended approach wherein an endpoint is assayed during or after the biological event of interest. Here we describe ShootingStar, a platform for perturbation analysis invivo, which combines live imaging, real-time image analysis, and automated optical perturbations. ShootingStar builds a quantitative record of the state of the sample being analyzed, which is used to automate the identification of target cells for perturbation, as well as to validate the impacts of the perturbation. We used ShootingStar to dissect the cellular basis of development, morphogenesis, and polarity in the lateral line of Danio rerio and the embryo of Caenorhabditis elegans. ShootingStar can be extended to diverse optical manipulations and enables more robust and informative single-cell perturbations in complex tissues.
Colavita A, Noblett N, Slatculescu C, Tran NN, Rankin A, Shah PK, Marshall TE, Bao Z, Perkins TJ, Hung J, Roenspies T, Kovacevic I, Chen Z, Tanner MR
[
Dev Cell,
2017]
Formation and resolution of multicellular rosettes can drive convergent extension (CE) type cell rearrangements during tissue morphogenesis. Rosette dynamics are regulated by both planar cell polarity (PCP)-dependent and -independent pathways. Here we show that CE is involved in ventral nerve cord (VNC) assembly in Caenorhabditis elegans. We show that a VANG-1/Van Gogh and PRKL-1/Prickle containing PCP pathway and a Slit-independent SAX-3/Robo pathway cooperate to regulate, via rosette intermediaries, the intercalation of post-mitotic neuronal cell bodies during VNC formation. We show that VANG-1 and SAX-3 are localized to contracting edges and rosette foci and act to specify edge contraction during rosette formation and to mediate timely rosette resolution. Simultaneous loss of both pathways severely curtails CE resulting in a shortened, anteriorly displaced distribution of VNC neurons at hatching. Our results establish rosette-based CE as an evolutionarily conserved mechanism of nerve cord morphogenesis and reveal a role for SAX-3/Robo in this process.