[
Wilehm Roux Arch Dev Biol,
1984]
The cellular phenotypes are described for 28 temperature-sensitive embryonic arrest mutants in 25 genes in the nematodeCaenorhabditis elegans. Cell lineages, and cellular and subcellular properties at the non-permissive temperature (26 C) have been studied by direct observation of individual cells in living embryos using Nomarski microscopy and high-resolution video recordings. The sequence, direction and time of division and the position of the individual cells have been compared to wild-type development up to at least the 100-cell stage (or earlier stage of arrest). Defects are related to the previously reported arrest stage, temperature-sensitive period, and to maternal effects. Most maternal mutants display defects in zygote formation. These include absence of pronuclear fusion or of polar bodies, absence or abnormal position of pseudocleavage or of the first division cleavage, anomalous cytoplasmic streaming, eggshell defects, abnormal cytoplasmic yolk granules, extra(pro)nuclei, endomitosis or arrest at the one-cell stage. During embryogenesis, many mutants show cellular and/or morphological abnormalities, including pseudopodia, blastocoel malformation, prolonged mitosis and membrane reformation, ill-defined membranes, segregation of extra nuclei, and cytoplasmic "plaques" at division. Most mutants display defects in cell lineage features, i.e. slow cell division rate, abnormal division sequence or direction. Three mutants show premature germ-line cell division, one of these also having a supernumerary germ-line division. Nine mutants show defects in the intestinal cell lineage, i.e. in division direction, in timing relative to gastrulation or in intestine anatomy. This survey of the cellular properties of the mutants provdes a basis for a more detailed, e.g. ultrastructural and molecular, study.
[
Dev Biol,
1983]
We have used standard tests to investigate the nature of gene expression of a new set of temperature-sensitive mutants defining 30 emb genes (essential for embryogenesis) in the nematode Caenorhabditis elegans. The mode of gene expression as determined by progeny tests for parental effects divides the genes into four classes. For 18 genes maternal gene expression is necessary and sufficient for normal embryogenesis; for 2 genes zygotic expression is necessary and sufficient; for 7 genes either maternal or zygotic expression is sufficient; for 3 genes both maternal and zygotic expression are necessary. One mutant displayed partial paternal sufficiency. The results of temperature-shift experiments define two "execution stages," corresponding to the limits of the temperature- sensitive period (TSP), and indicate the nature and the time of action or synthesis of the gene products. Most of the maternally expressed genes have very early execution stages indicating translation before fertilization, but some are temperature sensitive late in embryogenesis. Early execution stages for 2 zygotically necessary genes demonstrate that the zygotic genome can be active in the earliest stages of embryogenesis. All taken together, the mode of gene expression, TSP, and arrest stage (terminal phenotype) allow us to classify functionally and begin to order the genes essential for embryogenesis. The results indicate a preeminent role for maternal genes and gene products in embryogenesis, in agreement with the results of
[
Dev Cell,
2017]
Kinase translocation reporters (KTRs) are genetically encoded fluorescent activity sensors that convert kinase activity into a nucleocytoplasmic shuttling equilibrium for visualizing single-cell signaling dynamics. Here, we adapt the first-generation KTR forextracellular signal-regulated kinase (ERK) to allow easy implementation invivo. This sensor, "ERK-nKTR," allows quantitative and qualitative assessment of ERK activity by analysis of individual nuclei and faithfully reports ERK activity during development and neural function in diverse cell contexts in Caenorhabditis elegans. Analysis of ERK activity over time in the vulval precursor cells, a well-characterized paradigm of epidermal growth factor receptor (EGFR)-Ras-ERK signaling, has identified dynamic features not evident from analysis of developmental endpoints alone, including pulsatile frequency-modulated signaling associated with proximity to the EGF source. The toolkit described here will facilitate studies of ERK signaling in other C.elegans contexts, and the design features will enable implementation of this technology in other multicellular organisms.