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[
WormBook,
2005]
Nervous systems are characterized by an astounding degree of cellular diversity. The nematode Caenorhabditis elegans has served as a valuable model system to define the genetic programs that serve to generate cellular diversity in the nervous system. This review discusses neuronal diversity in C. elegans and provides an overview of the molecular mechanisms that define and specify neuronal cell types in C. elegans.
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[
WormBook,
2006]
Although several Caenorhabditis species are now studied in laboratories in great detail, the knowledge of the ecology of most Caenorhabditis species is scarce. In this chapter we present data on the habitat, animal associations, and geographical distribution of the eighteen described and five undescribed Caenorhabditis species currently known to science. The habitats of these species are very diverse, ranging from rotting cactus tissue to inflamed auditory canals of zebu cattle. Some species, including C. elegans , have only been isolated from anthropogenic habitats. Consequently, their natural habitat is unknown. All Caenorhabditis species are colonizers of nutrient- and bacteria-rich substrates and none of them is a true soil nematode. Dauer juveniles of many Caenorhabditis species were shown to be associated with terrestrial arthropods or gastropods. An association with invertebrates is also likely for the remaining species. The type of association is either phoresy (for transport to a new habitat) or necromeny (to secure the body of the associated animal as a future food source). There are also some records of Caenorhabditis species associated with vertebrates. The Caenorhabditis stem species was probably a colonizer of nutrient-rich substrates and was phoretic on arthropods. Some evolutionary trends within the taxon are discussed.
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[
Genetics,
2020]
<i>Caenorhabditis elegans</i>' behavioral states, like those of other animals, are shaped by its immediate environment, its past experiences, and by internal factors. We here review the literature on <i>C. elegans</i> behavioral states and their regulation. We discuss dwelling and roaming, local and global search, mate finding, sleep, and the interaction between internal metabolic states and behavior.
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[
Genetics,
2023]
The nematode Caenorhabditis elegans is a research model organism particularly suited to the mechanistic understanding of synapse genesis in the nervous system. Armed with powerful genetics, knowledge of complete connectomics, and modern genomics, studies using C. elegans have unveiled multiple key regulators in the formation of a functional synapse. Importantly, many signaling networks display remarkable conservation throughout animals, underscoring the contributions of C. elegans research to advance the understanding of our brain. In this chapter, we will review up-to-date information of the contribution of C. elegans to the understanding of chemical synapses, from structure to molecules and to synaptic remodeling.
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[
Genetics,
2018]
Since the earliest days of research on nematodes, scientists have noted the developmental and morphological variation that exists within and between species. As various cellular and developmental processes were revealed through intense focus on <i>Caenorhabditis elegans</i>, these comparative studies have expanded. Within the genus <i>Caenorhabditis</i>, they include characterization of intraspecific polymorphisms and comparisons of distinct species, all generally amenable to the same laboratory culture methods and supported by robust genomic and experimental tools. The <i>C. elegans</i> paradigm has also motivated studies with more distantly related nematodes and animals. Combined with improved phylogenies, this work has led to important insights about the evolution of nematode development. First, while many aspects of <i>C. elegans</i> development are representative of <i>Caenorhabditis</i>, and of terrestrial nematodes more generally, others vary in ways both obvious and cryptic. Second, the system has revealed several clear examples of developmental flexibility in achieving a particular trait. This includes developmental system drift, in which the developmental control of homologous traits has diverged in different lineages, and cases of convergent evolution. Overall, the wealth of information and experimental techniques developed in <i>C. elegans</i> is being leveraged to make nematodes a powerful system for evolutionary cellular and developmental biology.
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[
Genetics,
2019]
Mitotic cell divisions increase cell number while faithfully distributing the replicated genome at each division. The <i>Caenorhabditis elegans</i> embryo is a powerful model for eukaryotic cell division. Nearly all of the genes that regulate cell division in <i>C. elegans</i> are conserved across metazoan species, including humans. The <i>C. elegans</i> pathways tend to be streamlined, facilitating dissection of the more redundant human pathways. Here, we summarize the virtues of <i>C. elegans</i> as a model system and review our current understanding of centriole duplication, the acquisition of pericentriolar material by centrioles to form centrosomes, the assembly of kinetochores and the mitotic spindle, chromosome segregation, and cytokinesis.
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[
WormBook,
2005]
Genetic mosaics can be used to gain insight into the cell specificity of gene function. How Caenorhabditis elegans mosaics are typically generated is reviewed, and several examples with relevance to developmental studies are mentioned. One example is
mpk-1 , which encodes a member of the Ras-MAP-kinase pathway.
mpk-1 mosaics have been a means of studying the distinct cells that require the gene for distinct fates during development. The gene
bre-5 is used as an example of the usefulness of mosaic analysis for non-developmental studies. Potential problems with mosaic analysis are discussed, and the power of combining mosaic analysis with cell- or tissue-specific promoters is mentioned.
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[
Genetics,
2022]
Over the last 20 years, studies of Caenorhabditis elegans natural diversity have demonstrated the power of quantitative genetic approaches to reveal the evolutionary, ecological, and genetic factors that shape traits. These studies complement the use of the laboratory-adapted strain N2 and enable additional discoveries not possible using only one genetic background. In this chapter, we describe how to perform quantitative genetic studies in Caenorhabditis, with an emphasis on C. elegans. These approaches use correlations between genotype and phenotype across populations of genetically diverse individuals to discover the genetic causes of phenotypic variation. We present methods that use linkage, near-isogenic lines, association, and bulk-segregant mapping, and we describe the advantages and disadvantages of each approach. The power of C. elegans quantitative genetic mapping is best shown in the ability to connect phenotypic differences to specific genes and variants. We will present methods to narrow genomic regions to candidate genes and then tests to identify the gene or variant involved in a quantitative trait. The same features that make C. elegans a preeminent experimental model animal contribute to its exceptional value as a tool to understand natural phenotypic variation.
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[
WormBook,
2005]
The normal karyotype of Caenorhabditis elegans, with its five pairs of autosomes and single pair of X chromosomes, is described. General features of chromosomes and global differences between different chromosomal regions are discussed. Abnormal karyotypes, including duplications, deficiencies, inversions, translocations and chromosome fusions are reviewed. The effects of varying ploidy and of varying gene dosage are summarized. Dosage-sensitive genes seem to be rare in C. elegans, and the organism is able to tolerate substantial levels of aneuploidy. However, autosomal hemizygosity for more than about 3 % of the total genome may be incompatible with viability.
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[
WormBook,
2005]
Nematodes are the most abundant type of animal on earth, and live in hot springs, polar ice, soil, fresh and salt water, and as parasites of plants, vertebrates, insects, and other nematodes. This extraordinary ability to adapt, which hints at an underlying genetic plasticity, has long fascinated biologists. The fully sequenced genomes of Caenorhabditis elegans and Caenorhabditis briggsae, and ongoing sequencing projects for eight other nematodes, provide an exciting opportunity to investigate the genomic changes that have enabled nematodes to invade many different habitats. Analyses of the C. elegans and C. briggsae genomes suggest that these include major changes in gene content; as well as in chromosome number, structure and size. Here I discuss how the data set of ten genomes will be ideal for tackling questions about nematode evolution, as well as questions relevant to all eukaryotes.