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[
Curr Biol,
2016]
To establish and maintain their complex morphology and function, neurons and other polarized cells exploit cytoskeletal motor proteins to distribute cargoes to specific compartments [1]. Recent studies in cultured cells have used inducible motor protein recruitment to explore how different motors contribute to polarized transport and to control the subcellular positioning of organelles [2,3]. Such approaches also seem promising avenues for studying motor activity and organelle positioning within more complex cellular assemblies, but their applicability to multicellular in vivo systems has so far remained unexplored. Here, we report the development of an optogenetic organelle transport strategy in the in vivo model system Caenorhabditis elegans. We demonstrate that movement and pausing of various organelles can be achieved by recruiting the proper cytoskeletal motor protein with light. In neurons, we find that kinesin and dynein exclusively target the axon and dendrite, respectively, revealing the basic principles for polarized transport. In vivo control of motor attachment and organelle distributions will be widely useful in exploring the mechanisms that govern the dynamic morphogenesis of cells and tissues, within the context of a developing animal.
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Johnson TE, Fukui HH, Curtsinger JW, Capra WB, Vaupel JW, Xiu L, Lithgow GJ, Khazaeli A, Pletcher S, Wang JL, Carey JR, Muller HG
[
Science,
1994]
A. Brooks et al. report that mortality increased exponentially for a cohort of 180,000 nematodes of the species Caenorhabditis elegans of the single genotype TJ1060 [
spe-9(
hc88)
fer-15(
b26)]. A closer look at the data reveals that from days 5 through 8 mortality increased at a rate of 0.58 +/- 0.0004, which is more than twice the rate thereafter (0.21 +/- 0.02). Such a "biphasic pattern," with death rates increasing rapidly at younger ages and more slowly at older ages, was also found in a genetically heterogeneous population of 79 recombinant-inbred (RI) strains.
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[
Nature,
1996]
Several animal taxa display a consistent left-right asymmetry of the body plan. In nematodes, dextrality predominates. However, we have now found a nematode species that has sinistral populations.
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[
Curr Biol,
2000]
During signaling by the Notch receptor, Notch's intracellular domain is cleaved, moves to the nucleus and associates with a DNA-binding protein of the CSL class (CSL for CBF1, Suppressor of Hairless (Su(H)), LAG-1); as a result, target genes are transcriptionally activated (reviewed in [1,2]). In Caenorhabditis elegans, a glutamine-rich protein called LAG-3 forms a ternary complex with the Notch intracellular domain and LAG-1 and appears to serve as a transcriptional activator that is critical for signaling [3]. Although database searches failed to identify a LAG-3-related protein, we surmised that Notch signaling in other organisms might involve an analogous activity.
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[
Science,
1977]
At a recent conference in Woods Hole, Massachusetts, investigators met to discuss the nematode Caenorhabditis elegans. This free-living worm may, according to some workers, become the Escherichia coli or at least the bacteriophage T4 of the animal world. Small (about 1mm in length) and semitransparent, C. elegans provides for research the advantages of a short life cycle (3 days) and a simple anatomy-it contains about 810 nongonadal nuclei. It is both easy to cultivate, on E. coli as a food source, and convenient for genetic analysis. Its genes are carried on five autosomes and a sex chromosome (X), and it has a genome size about 20 times that of E. coli. It generally reproduces as a self-fertilizing hermaphrodite (XX), but occasional males (XO), which arise by nondisjunction, permit sexual reproduction as well....
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[
Biochem J,
1996]
The MAGUKs are a family of membrane-associated guanylate kinases characterized by a common set of domains that bind polypeptide and nucleotide ligands. These domains are a guanylate kinase-like (GUK) domain, an SH3 domain, and one to three copies of a structure known as a PDZ or DHR domain. The PDZ/DHR domain was defined by homology with the Drosophila tumour suppressor discs-large (DLG), the post-synaptic density protein PSD-95 and the tight-junction protein Z0-1, and has recently been defined as a domain for binding polypeptide ligands. The three domain types that define MAGUKs are therefore all ligand-binding domains specialized either for binding polypeptides (PDZ, SH3) or nucleotides (GUK)...
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[
Neuromuscul Disord,
2004]
In her commentary on our recently published paper, A. de Luca questions the approach consisting in screening random molecules on a dystrophin-deficient invertebrate model (C. elegans) in order to identify potential therapeutic clues.
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[
J Mol Evol,
1996]
Transmembrane 4 superfamily (TM4SF) molecules are predominantly mammalian cell surface glycoproteins that are thought to transduce signals mediating cell development, activation, and motility. Analysis of the Genpept sequence database reveals YKK8, a novel member of the TM4SF in the nematode, Caenorhabditis elegans. YKK8 is a putative 27.4-kDa protein encoded by a gene on chromosome III of the C. elegans genome. The assignment of YKK8 to the TM4SF is justified by three criteria: statistical comparison of protein sequences, conserved TM4SF protein sequence motifs, and conserved TM4SF intron/exon boundaries in the genomic sequence. The discovery of a TM4SF molecule in the nematode extends this superfamily to a more primitive branch of the phylogenetic tree and suggests a fundamental role for TM4SF molecules in biology.
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[
Biophys Chem,
2005]
Lifespan regulation through gene expression involves complex biochemical processes. Unfortunately, current mathematical models for treating lifespan data afford little insight into the mechanisms that control longevity. In this work, we demonstrate the use of a novel kinetic model to successfully fit the lifespan curves of the nematode, Caenorhabditis elegans. Our findings show that population aging may be treated analogously to a dispersive chemical process [P.J. Skrdla, R.T. Robertson., J. Phys. Chem. B 109 10611 (2005)]. Much like the Gompertz model, only two fit parameters, alpha and beta, are needed to adequately describe the entire data set for each nematode population. These parameters relate a ''global first-order time constant'' and a ''global second-order rate constant'', with units of (time) and (time)(-2), respectively. In C. elegans, the increased longevity resulting from DAF-16 (a transcription factor) activity in the intestinal tissue correlates with a larger alpha value and a smaller beta value; the opposite is true for animals with shorter lifespans. A basic physical interpretation of the two parameters is provided.
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[
FEMS Microbiol Lett,
2014]
Staphylococcus lugdunensis is a human skin commensal organism, but it is considered as a virulent Staphylococcus species. In a previous study, we described the first S.lugdunensis autolysin, AtlL. This enzyme displays two enzymatic domains and generates two peptidoglycan hydrolases, an N-acetylmuramoyl-l-alanine amidase and an N-acetylglucosaminidase. In this study, to further investigate the functions of this autolysin, a atlL mutant was constructed. The microscopic examination of the mutant showed cell aggregates and revealed a rough outer cell surface demonstrating, respectively, the roles of AtlL in cell separation and peptidoglycan turnover. This atlL mutant exhibited a lower susceptibility to Triton X-100-induced autolysis assays and appears to be more resistant to cell wall antibiotic-induced lysis and death compared with its parental strain. The atlL mutation affected the biofilm formation capacity of S.lugdunensis. Furthermore, the atlL mutant showed trends toward reduced virulence using the Caenorhabditis elegans model. Overall, AtlL appears as a major cell wall autolysin of S.lugdunensis implicated in cell separation, in stress-induced autolysis and in bacterial pathogenesis.