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Curr Biol,
2006]
Through experience, the nematode worm Caenorhabditis elegans learns to distinguish high quality bacteria--food--from low quality or toxic bacteria. Increased release of the neurotransmitter serotonin onto identified interneurons determines whether C. elegans chooses to feed or leave.
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Nature Structural & Molecular Biology,
2004]
A recent study reports the RNA sequences that bind to the translational repressor protein GLD-1. The data suggest that a network of developmental genes may be regulated by GLD-1 or related STAR proteins through silencing or alternative splicing.
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Physiol Genomics,
2003]
Life developed in a stressful environment. Stressors at the cellular level include heat, hypoxia, oxidative or reductive substances, mechanical or osmotic pressure, and toxic compounds like heavy metals. Various molecular pathways, more or less specific for the different stressors, developed during evolution to combat the molecular consequences of cell stress. Thermal stress induces the induction of a highly conserved protein family, the heat shock proteins (HSP).
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Science,
2003]
Restriction of the number of calories consumed extends longevity in many organisms. In rodents, caloric restriction decreases the levels of plasma glucose and insulin-like growth factor I (IGF-1) and postpones or attenuates cancer, immunosenescence, and inflammation without irreversible side effects. In organisms ranging from yeast to mice, mutations in glucose or IGF-I-like signaling pathways extend life-span but also cause glycogen or fat accumulation and dwarfism. This information suggests a new category of drugs that could prevent or postpone diseases of aging with few adverse effects.
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Methods Cell Biol,
1995]
Genetic balancers are genetic constructs or chromosomal rearrangements that allow lethal or sterile mutations to be stably maintained in heterozygotes. In this chapter we use the term balancer primarily to refer to chromosomal duplications or rearrangements that suppress crossing over. In addition, we define lethal as any mutation that blocks survival or reproduction. Phenotypes associated with lethal mutations in Caenorhabditis elegans range from egg or larval lethality to adult sterility and maternal effect lethality, and can include conditional effects such as temperature sensitivity. The number of essential genes in C. elegans (those identified by lethal mutations) may range as high as 7000 according to genetic estimates. Thus, lethal mutations constitute a rich source of information about basic biological processes in this nematode.
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Trends in Ecology & Evolution,
1999]
In a recent TREE news & comment, Gadagkar made some useful comments on LaMunyon and Ward's interesting study on sexual reproduction in nematodes. I think, however, that he - and LaMunyon and Ward - have confused the benefits of sex for species or demes with those for individuals or genes.
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Journal of Gerontology,
1999]
In recent years, oxidative damage to macromolecules has gained popularity as the basis of the molecular mechanism of aging. Martin proposes oxidative damage to macromolecules as one of the major public mechanisms of aging. Interest in modifications of protein by reactive oxygen species in aging was apparently introduced by Stadtman. Although various types of oxidative modifications can occur in proteins, carbonyl residues believed to be generated by metal catalyzed reaction or otherwise introduced by lysine, arginine and/or proline residues in vivo are often used as a marker of direct or
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Dev Biol,
2017]
Breaking symmetry in populations of uniform cells, to induce adoption of an alternative cell fate, is an essential developmental mechanism. Similarly, domain and boundary establishment are crucial steps to forming organs during development. Notch signaling is a pathway ideally suited to mediating precise patterning cues, as both receptors and ligands are membrane-bound and can thus act as a precise switch to toggle cell fates on or off. Fine-tuning of signaling by positive or negative feedback mechanisms dictate whether signaling results in lateral induction or lateral inhibition, respectively, allowing Notch to either induce entire regions of cell specification, or dictate binary fate choices. Furthermore, pathway activity is modulated by Fringe modification of receptors or ligands, co-expression of receptors with ligands, mode of ligand presentation, and cell surface area in contact. In this review, we describe how Notch signaling is fine-tuned to mediate lateral induction or lateral inhibition cues, and discuss examples from C.elegans, D. melanogaster and M. musculus. Identifying the cellular machinery dictating the choice between lateral induction and lateral inhibition highlights the versatility of the Notch signaling pathway in development.
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[
Trends in Ecology & Evolution,
1999]
In a recent TREE news & comment, Gadagkar made some useful comments on LaMunyon and Ward's interesting study on sexual reproduction in nematodes. I think, however, that he - and LaMunyon and Ward - have confused the benefits of sex for species or demes with those for individuals or genes. For females and hermaphrodites (but not for species or demes), the twofold cost of sexual reproduction or producing males' in Maynard Smith's sense implies the cost of producing offspring that have only half of the hermaphrodite parent's genome set - not directly that of producing males. An offspring of a hermaphrodite Caenorhabditis briggsae inherits half, not more, of each parental genome set. The hermaphrodite parent still pays the two fold cost of sexual reproduction in the same way as
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Dev Growth Differ,
1998]
Special cytoplasm, called germ plasm, that is essential for the differentiation of germ cells is localized in a particular region of Caenorhabditis elegans, Drosophila and Xenopus eggs. The mode of founder cell formation of germline, the origin and behavior of the germline granules, and the molecules localized in germline cells are compared in these organisms. The common characteristics of the organisms are mainly as follows. First, the founder cells of germline are established before the initiation of gastrulation. Second, the germline granules or their derivatives are always present in germline cells or germ cells throughout the life cycle in embryos, larvae, and adults. Lastly, among the proteins localized in the germ plasm, only Vasa protein or its homolog is detected in the germline cells or germ cells throughout the life cycle. As the protein of vasa homolog has been reported to be also localized in the germline-specific structure or nuage in some of the organisms without the germ plasm, the possibility that the mechanism for differentiation of primordial germ cells is basically common in all organisms with or without the germ plasm is discussed.