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Methods Mol Biol,
2006]
Because of technical hurdles, large-scale cell culture methods have not been widely exploited until recently for the study of Caenorhabditis elegans. Culturing differentiated cells from larvae and adult worms is probably not technically feasible because of difficulties in removing the animal''s cuticle and dissociating cells. In contrast, large numbers of developing embryo cells can be isolated relatively easily. When placed in culture, embryo cells undergo terminal differentiation within 24 h. Cultured embryo cells have been used recently to characterize ion channel function and regulation and to determine cell specific gene expression patterns. This chapter will provide a detailed description of the methods for isolating and culturing C. elegans embryo cells.
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Cell Mol Life Sci,
2015]
Germ cells must transmit genetic information across generations, and produce gametes while also maintaining the potential to form all cell types after fertilization. Preventing the activation of somatic programs is, therefore, crucial to the maintenance of germ cell identity. Studies in Caenorhabditis elegans, Drosophila melanogaster, and mouse have revealed both similarities and differences in how somatic gene expression is repressed in germ cells, thereby preventing their conversion into somatic tissues. This review will focus on recent developments in our understanding of how global or gene-specific transcriptional repression, chromatin regulation, and translational repression operate in the germline to maintain germ cell identity and repress somatic differentiation programs.
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J Dev Biol,
2020]
The potential of a cell to produce all types of differentiated cells in an organism is termed totipotency. Totipotency is an essential property of germ cells, which constitute the germline and pass on the parental genetic material to the progeny. The potential of germ cells to give rise to a whole organism has been the subject of intense research for decades and remains important in order to better understand the molecular mechanisms underlying totipotency. A better understanding of the principles of totipotency in germ cells could also help to generate this potential in somatic cell lineages. Strategies such as transcription factor-mediated reprogramming of differentiated cells to stem cell-like states could benefit from this knowledge. Ensuring pluripotency or even totipotency of reprogrammed stem cells are critical improvements for future regenerative medicine applications. The <i>C. elegans</i> germline provides a unique possibility to study molecular mechanisms that maintain totipotency and the germ cell fate with its unique property of giving rise to meiotic cells Studies that focused on these aspects led to the identification of prominent chromatin-repressing factors such as the <i>C. elegans</i> members of the Polycomb Repressive Complex 2 (PRC2). In this review, we summarize different factors that were recently identified, which use molecular mechanisms such as control of protein translation or chromatin repression to ensure maintenance of totipotency and the germline fate. Additionally, we focus on recently identified factors involved in preventing transcription-factor-mediated conversion of germ cells to somatic lineages. These so-called reprogramming barriers have been shown in some instances to be conserved with regard to their function as a cell fate safeguarding factor in mammals. Overall, continued studies assessing the different aspects of molecular pathways involved in maintaining the germ cell fate in <i>C. elegans</i> may provide more insight into cell fate safeguarding mechanisms also in other species.
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Trends Cell Biol,
2009]
Development requires the translation of stored maternal messenger RNAs (mRNAs) in a spatial and temporally specified manner. Maternal mRNAs are often in large RNA-protein (RNP) granules. Recent papers reveal that maternal mRNA granules in Caenorhabditis elegans oocytes and early development are dynamic and related to P-bodies and stress granules, which are conserved RNP granules seen in somatic cells. In addition, a highly conserved putative RNA helicase, termed CGH-1 in C. elegans, is now shown to be important for both for translation repression and the stability of stored mRNAs. The analysis of CGH-1 ortholog functions in somatic cells and its interacting proteins indicate possible mechanisms by which this protein family might stabilize stored maternal mRNAs.
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Genetics,
2023]
The studies of cell fate and lineage specification are fundamental to our understanding of the development of multicellular organisms. Caenorhabditis elegans has been one of the premiere systems for studying cell fate specification mechanisms at single cell resolution, due to its transparent nature, the invariant cell lineage, and fixed number of somatic cells. We discuss the general themes and regulatory mechanisms that have emerged from these studies, with a focus on somatic lineages and cell fates. We next review the key factors and pathways that regulate the specification of discrete cells and lineages during embryogenesis and postembryonic development; we focus on transcription factors and include numerous lineage diagrams that depict the expression of key factors that specify embryonic founder cells and postembryonic blast cells, and the diverse somatic cell fates they generate. We end by discussing some future perspectives in cell and lineage specification.
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Seminars in Developmental Biology,
1994]
Germ cell development in Caenorhabditis elegans involves three processes a shift from the mitotic to the meiotic cell cycle; the adoption of a male or female sexual identity; and differentiation into a functional gamete. All three aspects of germline development appear to be regulated, at least in part, by the soma. We discuss cell ablation, genetic and molecular studies that have shed light on the nature of the signal transduction systems mediating intracellular communication between germline and somatic tissues of the nematode.
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Curr Opin Genet Dev,
2003]
Recent studies in Caenorhabditis elegans implicate PcG- and NuRD-like chromatin regulators in the establishment and maintenance of germline-soma distinctions. Somatic cells appear to utilize NuRD-related nucleosome-remodeling factors to overwrite germline-specific chromatin states that are specified through PcG-like activities. The germline, in turn, may rely on an asymmetrically inherited inhibitor to prevent chromatin reorganization that would otherwise erase pluripotency.
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Trends in Genetics,
1987]
Tc1 is a 1.6 kbp DNA sequence present in about 30 copies in some strains of C. elegans and 300 or more copies in other strains. Tc1 elements excise much more frequently in somatic cells than in the germ line. Germ-line transposition of Tc1 has been detected and is under genetic control. Tc1 has become very useful as a tool for cloning C. elegans genes identified soley by mutation.
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Ageing Res Rev,
2005]
Germline immortality is a topic that has intrigued theoretical biologists interested in aging for over a century. The germ cell lineage can be passed from one generation to the next, indefinitely. In contrast, somatic cells are typically only needed for a single generation and are then discarded. Germ cells may, therefore, harbor rejuvenation mechanisms that enable them to proliferate for eons. Such processes are thought to be either absent from or down-regulated in somatic cells, although cell non-autonomous forms of rejuvenation are formally possible. A thorough description of mechanisms that foster eternal youth in germ cells is lacking. The mysteries of germline immortality are being addressed in the nematode Caenorhabditis elegans by studying mutants that reproduce normally for several generations but eventually become sterile. The mortal germline mutants probably become sterile as a consequence of accumulating various forms of heritable cellular damage. Such mutants are abundant, indicating that several different biochemical pathways are required to rejuvenate the germline. Thus, forward genetics should help to define mechanisms that enable the germline to achieve immortality.
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Cell,
1998]
Many changes occur as an animal ages. To name a few, proteins become modified and cross-linked, somatic mutations accumulate, stress resistance decreases, and the probability of death increases. One reason for these changes is thought to be oxidative damage to macromolecules and lipid membranes, caused by superoxides and other free-radicals resulting from aerobic metabolism. In the somatic cells, this damage can be partially but never completely counteracted by mechanisms for elimination of free radicals as well as turnover and repair of macromolecules.