-
[
Elife,
2021]
A new imaging approach can distinguish between cells destined to stop proliferating and those committed to re-entering the cell cycle in live animals.
-
[
Worm Breeder's Gazette,
1994]
Mono- and Polycistronic pre-mRNA Splicing in a C. elegans embryo extract
-
[
Curr Biol,
2015]
A pool of proliferating germline stem cells is essential for gamete production in Caenorhabditis elegans. A new study applies sophisticated live imaging to assess mitotic progression and cell cycle control in these cells, yielding new insights into stem cell division.
-
[
PLoS Comput Biol,
2021]
Isogenic cells cultured together show heterogeneity in their proliferation rate. To determine the differences between fast and slow-proliferating cells, we developed a method to sort cells by proliferation rate, and performed RNA-seq on slow and fast proliferating subpopulations of pluripotent mouse embryonic stem cells (mESCs) and mouse fibroblasts. We found that slowly proliferating mESCs have a more naive pluripotent character. We identified an evolutionarily conserved proliferation-correlated transcriptomic signature that is common to all eukaryotes: fast cells have higher expression of genes for protein synthesis and protein degradation. This signature accurately predicted growth rate in yeast and cancer cells, and identified lineage-specific proliferation dynamics during development, using C. elegans scRNA-seq data. In contrast, sorting by mitochondria membrane potential revealed a highly cell-type specific mitochondria-state related transcriptome. mESCs with hyperpolarized mitochondria are fast proliferating, while the opposite is true for fibroblasts. The mitochondrial electron transport chain inhibitor antimycin affected slow and fast subpopulations differently. While a major transcriptional-signature associated with cell-to-cell heterogeneity in proliferation is conserved, the metabolic and energetic dependency of cell proliferation is cell-type specific.
-
[
Curr Biol,
2006]
The transition from oocyte to embryo is among the most enthralling events in developmental biology. Recent studies of this transition in the nematode Caenorhabditis elegans have revealed how conserved kinases administer the destruction of key oocyte meiotic regulators to create an embryo.
-
[
Dev Biol,
1986]
During development Caenorhabditis elegans changes from an embryo that is relatively spherical in shape to a long thin worm. This paper provides evidence that the elongation of the body is caused by the outermost layer of embryonic cells, the hypodermis, squeezing the embryo circumferentially. The hypodermal cells surround the embryo and are linked together by cellular junctions. Numerous circumferentially oriented bundles of microfilaments are present at the outer surfaces of the hypodermal cells as the embryo elongates. Elongation is associated with an apparent pressure on the internal cells of the embryo, and cytochalasin D reversibly inhibits both elongation and the increase in pressure. Circumferentially oriented microtubules also are associated with the outer membranes of the hypodermal cells during elongation. Experiments with the microtubule inhibitors colcemid, griseofulvin, and nocodazole suggest that the microtubules function to distribute across the membrane stresses resulting from microfilament contraction, such that the embryo decreases in circumference uniformly during elongation. While the cytoskeletal organization of the hypodermal cells appears to determine the shape of the embryo during elongation, an extracellular cuticle appears to maintain the body shape after elongation.
-
[
Worm Breeder's Gazette,
1977]
A method for fixing and embedding C. elegans eggs will be introduced. It involves prolonged osmium or glutaraldehyde-osmium fixation at elevated temperatures. This procedure works on all stages of embryogenesis. 16 embryos in various stages ranging from an uncleaved zygote to a prehatching 'pretzel' have been serially sectioned. The analysis of a 5-hour embryo with 294 cells and of a 7-hour embryo with 540 cells will be presented. Data from the 5-hour embryo supplement the Nomarski results. Data from the 7-hour embryo will be compared with the anatomy of the young L1 worked out by Sulston and Horvitz.
-
[
Curr Biol,
2011]
Embryonic morphogenesis requires the coordination of forces across multiple tissues and their associated extracellular matrices. A new study reports a mechanical feedback loop in the Caenorhabditis elegans embryo between muscle and epidermis that may provide a model for understanding how tissues coordinate morphogenetic events in the embryo.
-
Wu, Y., Guo, M., Moyle, M., Ardiel, E., Shroff, H., Bokinsky, A., Santella, A., McCreedy, E., Colon-Ramos, D., Karaj, N., Duncan, L., Bao, Z., Levin, M., Mohler, W., Lauziere, A., Harvey, B., Christensen, R.P.
[
International Worm Meeting,
2019]
The Caenorhabditis elegans embryo represents an excellent model system in which to study tissue formation. However, the onset of twitching and elongation makes data analysis during the second half of embryogenesis difficult. Previously, we developed software to enable computational untwisting of the C. elegans embryo, removing the effects of embryo movement and placing embryo images in a common reference frame for analysis. We have now improved our software suite to incorporate more user-friendly positional tracking and better segmentation, reducing clipping of images around the edges of the embryo. We also apply deep learning to segment nuclei in a semi-automated fashion. We apply our software to generate a map showing the position of 158 nuclei in the post-twitching worm embryo, as a partial step in the generation of a complete embryonic nuclear atlas. Tracked nuclei include 16 neurons and 81 body wall muscles. Our improved tools, combined with pre-twitching work from our collaborators on the WormGUIDES project, allow us to pursue the goal of developing a complete nuclear and neurite outgrowth atlas for the nematode embryo from the two cell stage until hatching.
-
[
Cold Spring Harb Protoc,
2010]
The Caenorhabditis elegans embryo is particularly amenable to microscopy and embryological studies because of its short developmental time, transparent shell, and nonpigmented cells. The agar mount described in this protocol is an easy way to prepare live C. elegans embryos for microscopic visualization. The mount slightly embeds the embryo in agar to hold it in place. The mount also slightly compresses the embryo to provide consistent orientation such that every embryo will be positioned with either its right side or its left side facing the objective. Other techniques can result in random orientations that complicate analysis and make identification of individual blastomeres more challenging.