-
Programmed cell death is a common cell fate in most if not all multicellular organisms. Apoptosis, which will be used as a synonym for programmed cell death throughout this chapter, occurs extensively during development as well as during later life. The development of the nematode worm Caenorhabditis elegans provides a good example of the extensive use of programmed cell death.
-
[
WormBook,
2005]
Protein kinases are one of the largest and most influential of gene families: constituting some 2% of the proteome, they regulate almost all biochemical pathways and may phosphorylate up to 30% of the proteome. Bioinformatics and comparative genomics were used to determine the C. elegans kinome and put it in evolutionary and functional context. Kinases are deeply conserved in evolution, and the worm has family homologs for over 80% of the human kinome. Almost half of the 438 worm kinases are members of worm-specific or worm-expanded families. Such radiations include genes involved in spermatogenesis, chemosensation, Wnt signaling and FGF receptor-like kinases. The C. briggsae kinome is largely similar apart from the expanded classes, showing that such expansions are evolutionarily recent.
-
[
Methods Mol Biol,
2020]
This chapter presents methods for exploiting the powerful tools available in the nematode worm Caenorhabditis elegans to understand the in vivo functions of cerebral cavernous malformation (CCM) genes and the organization of their associated signaling pathways. Included are methods for assessing phenotypes caused by loss-of-function mutations in the worm CCM genes
kri-1 and
ccm-3, CRISPR-based gene editing techniques, and protocols for conducting high-throughput forward genetic and small molecule screens.
-
[
WormBook,
2005]
Ion channels are the "transistors" (electronic switches) of the brain that generate and propagate electrical signals in the aqueous environment of the brain and nervous system. Potassium channels are particularly important because, not only do they shape dynamic electrical signaling, they also set the resting potentials of almost all animal cells. Without them, animal life as we know it would not exist, much less higher brain function. Until the completion of the C. elegans genome sequencing project the size and diversity of the potassium channel extended gene family was not fully appreciated. Sequence data eventually revealed a total of approximately 70 genes encoding potassium channels out of the more than 19,000 genes in the genome. This seemed to be an unexpectedly high number of genes encoding potassium channels for an animal with a small nervous system of only 302 neurons. However, it became clear that potassium channels are expressed in all cell types, not only neurons, and that many cells express a complex palette of multiple potassium channels. All types of potassium channels found in C. elegans are conserved in mammals. Clearly, C. elegans is "simple" only in having a limited number of cells dedicated to each organ system; it is certainly not simple with respect to its biochemistry and cell physiology.
-
[
WormBook,
2006]
Studies in C. elegans have begun to reveal new components and new mechanisms associated with intracellular membrane traffic in a variety of cell types. The worm benefits from many of the advantages of yeast as a genetically tractable organism for these kinds of studies while offering the unique opportunity to probe how these pathways have been extended and modified in the context of a multicellular animal undergoing development to produce diverse cell types such as muscles, nerves, and polarized epithelia. This review summarizes recent work elucidating endocytic pathways, primarily in the worm germ line and coelomocytes, and also touches on diverse studies of secretion, especially in ectodermal cells of epithelial character.
-
[
1979]
We have isolated temperature sensitive maternal effect mutants in the free-living nematode Caenorhabditis elegans. We use C. elegans for several basic reasons. It is easy to culture in the laboratory and it has a rapid life cycle. The genetics of C. elegans have been elucidated by Brenner and more recently have been refined by the lethal analysis of Herman et. al. Both embryonic and postembryonic development can be observed directly and conveniently on the living worm with Nomarski differential interference optics because egg shell and worm cuticle are transparent. The precise embryonic cell lineages of C. elegans are known from fertilization to the 200 blastomere stage. All of the postembryonic somatic cell lineages are precisely known. It ...
-
[
WormBook,
2006]
Contrary to textbook dogma, nematodes are not only highly diverse, but often also complex and biologically specialized metazoans. Just a few of the many fascinating adaptations are reviewed in this chapter, as a prelude to a quick tour through phylogenetic relationships within the phylum. Small Subunit rDNA sequences have confirmed several controversial prior hypotheses, as well as revealing some unexpected relationships, resulting in a recent proposal for revised classification. Three major lineages exist within the phylum: Chromadoria, Enoplia and Dorylaimia. The exact order of appearance of these lineages is not yet resolved, which also leaves room for uncertainty about the biology and morphology of the exclusive common ancestor of nematodes. Enoplia and Dorylaimia differ considerably in many respects from C. elegans, which is a member of Chromadoria. The latter group is extremely diverse in its own right, for example in ecological range, in properties of the cuticle and in structure of the pharynx. The formerly relatively widely accepted class Secernentea is deeply nested within Chromadoria, and has therefore recently been relegated to the rank and name of order Rhabditida. Within this order, closer relatives of C. elegans include strongylids, diplogasterids and bunonematids. Tylenchs, cephalobs and panagrolaimids are also members of Rhabditida, albeit probably more distantly related to C. elegans.
-
[
Methods Mol Biol,
2011]
PhospoPep version 2.0 is a project to support systems biology signaling research by providing interactive interrogation of MS-derived phosphorylation data from four different organisms. Currently the database hosts phosphorylation data from the fly (Drosophila melanogaster), human (Homo sapiens), worm (Caenorhabditis elegans), and yeast (Saccharomyces cerevisiae). The following will give an overview of the content and usage of the PhosphoPep database.
-
[
1987]
We describe an experimental system in which to study gene-specific segregation mechanisms during early development of C. elegans. A non-specific esterase, of unknown physiological function, has convenient properties as a biochemical marker of differentiation: expression is localized to the gut lineage, is due to transcription during zygotic development and is lineage autonomous. The timing of esterase expression does not depend either on the normal number of rounds of cytokinesis or on the normal number of rounds of DNA replication; thus some other clock mechanism must be invoked. We descrbe experiments suggesting that DNA strands donated by the sperm do not co-segregate during development of the next generation.
-
[
1979]
In many invertebrates, cell lineages are apparently invariant from individual to individual. A given precursor cell follows a specific pattern of cell divisions, and its descendants follow fates that correspond to their respective positions in the lineage tree. Such a reproducible sequence of events provides an excellent system for studying how cells come to pursue particular fates during development. We have been interested to know if a cell's fate is specified by factors intrinsic to the cell, or if it is influenced by interactions between the cell and its environment. C. elegans is a particularly suitable organism for lineage studies because it is transparent throughout its life cycle, and because it consists of relatively few cells. Furthermore, C. elegans is a favorable organism for genetics, so the control of cell lineages can be studied by characterizing mutations that are defective in known lineages. The cell lineages of C. elegans have been described in the embryo to the 182 cell stage and after hatching. Approximately 50 cells resume divisions post-embyronically. In the somatic tissues, the number of cells (or nuclei) is increased from about 550 to about 950 in hermaphrodites and to about 1025 in males. These post-embryonic lineages are essentially invariant from worm to worm. As the worm enlarges and matures sexually, cells (or nuclei) are added to previously existing tissues (hypodermis, muscle, gut, and nervous system), and structures necessary for reproduction are elaborated. The latter include a gonad in both sexes, a vulva in hermaphrodites, and a tail specialized for copulation in males. This paper summarizes the results of laser ablation experiments performed on cells in the post-embryonic lineages of C. elegans. In particular, we focus on those experiments that demonstrate a regulative capacity in the cells of this predominantly invariant system. The post-embyronic lineages have the practical advantage for these studies that they can be traced by direct observation of the cells as they divide and assume their final fate. The regulative response, therefore, can be described at a level of cellular detail that has not been possible in other deletion studies. Our aim in performing these experiments is to infer how cells are controlled during normal development from their behavior in