Bondaz A et al. (2019) J Cell Biol "Cell polarity-dependent centrosome separation in the C. elegans embryo."

Bondaz A, Gotta M, Cirillo L, Meraldi P

[J Cell Biol, 2019]

In animal cells, faithful chromosome segregation depends on the assembly of a bipolar spindle driven by the timely separation of the two centrosomes. Here we took advantage of the highly stereotypical cell divisions in <i>Caenorhabditis elegans</i> embryos to identify new regulators of centrosome separation. We find that at the two-cell stage, the somatic AB cell initiates centrosome separation later than the germline P1 cell. This difference is strongly exacerbated by the depletion of the kinesin-13 KLP-7/MCAK, resulting in incomplete centrosome separation at NEBD in AB but not P1. Our genetic and cell biology data indicate that this phenotype depends on cell polarity via the enrichment in AB of the mitotic kinase PLK-1, which itself limits the cortical localization of the dynein-binding NuMA orthologue LIN-5. We postulate that the timely separation of centrosomes is regulated in a cell type-dependent manner.

Abbatemarco S et al. (2021) J Cell Sci "PQN-59 and GTBP-1 contribute to stress granule formation but are not essential for their assembly in C. elegans embryos."

Bondaz A, Abbatemarco S, Wang J, Schwager F, Hammell CM, Gotta M

[J Cell Sci, 2021]

When exposed to stressful conditions, eukaryotic cells respond by inducing the formation of cytoplasmic ribonucleoprotein complexes called stress granules. Here we use C. elegans to study two proteins that are important for stress granule assembly in human cells: PQN-59, the human UBAP2L ortholog, and GTBP-1, the human G3BP1/2 ortholog. Both proteins assemble into stress granules in the embryo and in the germline when C. elegans is exposed to stressful conditions. None of the two proteins is essential for the assembly of stress-induced granules, as shown by the single and combined depletions by RNAi, and neither pqn-59 nor gtbp-1 mutant embryos show higher sensitivity to stress than control embryos. We find that pqn-59 mutants display reduced progeny and a high percentage of embryonic lethality, phenotypes that are not dependent on stress exposure and that are not shared with gtbp-1 mutants. Our data indicate that, in contrast to human cells, PQN-59 and GTBP-1 are not required for stress granule formation but that PQN-59 is important for C. elegans development.

Quartey MO et al. (2021) Sci Rep "The A(1-38) peptide is a negative regulator of the A(1-42) peptide implicated in Alzheimer disease progression."

Pennington PR, Heistad RM, Nyarko JNK, Barnes JR, Bolanos MAC, Parsons MP, Knudsen KJ, De Carvalho CE, Leary SC, Mousseau DD, Buttigieg J, Maley JM, Quartey MO

[Sci Rep, 2021]

The pool of -Amyloid (A) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for A peptides. We examined how a naturally occurring variant, e.g. A(1-38), interacts with the AD-related variant, A(1-42), and the predominant physiological variant, A(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that A(1-38) interacts differently with A(1-40) and A(1-42) and, in general, A(1-38) interferes with the conversion of A(1-42) to a -sheet-rich aggregate. Functionally, A(1-38) reverses the negative impact of A(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an A(1-42) phenotype in Caenorhabditis elegans. A(1-38) also reverses any loss of MTT conversion induced by A(1-40) and A(1-42) in HT-22 hippocampal neurons and APOE 4-positive human fibroblasts, although the combination of A(1-38) and A(1-42) inhibits MTT conversion in APOE 4-negative fibroblasts. A greater ratio of soluble A(1-42)/A(1-38) [and A(1-42)/A(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that A(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant A(1-42).

Tangrodchanapong T et al. (2020) Front Pharmacol "Frondoside A Attenuates Amyloid- Proteotoxicity in Transgenic Caenorhabditis elegans by Suppressing Its Formation."

Tangrodchanapong T, Sobhon P, Meemon K

[Front Pharmacol, 2020]

Oligomeric assembly of Amyloid- (A) is the main toxic species that contribute to early cognitive impairment in Alzheimer's patients. Therefore, drugs that reduce the formation of A oligomers could halt the disease progression. In this study, by using transgenic <i>Caenorhabditis elegans</i> model of Alzheimer's disease, we investigated the effects of frondoside A, a well-known sea cucumber <i>Cucumaria frondosa</i> saponin with anti-cancer activity, on A aggregation and proteotoxicity. The results showed that frondoside A at a low concentration of 1 M significantly delayed the worm paralysis caused by A aggregation as compared with control group. In addition, the number of A plaque deposits in transgenic worm tissues was significantly decreased. Frondoside A was more effective in these activities than ginsenoside-Rg3, a comparable ginseng saponin. Immunoblot analysis revealed that the level of small oligomers as well as various high molecular weights of A species in the transgenic <i>C. elegans</i> were significantly reduced upon treatment with frondoside A, whereas the level of A monomers was not altered. This suggested that frondoside A may primarily reduce the level of small oligomeric forms, the most toxic species of A. Frondoside A also protected the worms from oxidative stress and rescued chemotaxis dysfunction in a transgenic strain whose neurons express A. Taken together, these data suggested that low dose of frondoside A could protect against A-induced toxicity by primarily suppressing the formation of A oligomers. Thus, the molecular mechanism of how frondoside A exerts its anti-A aggregation should be studied and elucidated in the future.

Viney ME et al. (2004) Naturwissenschaften "Is dauer pheromone of Caenorhabditis elegans really a pheromone?"

Viney ME, Franks NR

[Naturwissenschaften, 2004]

Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called 'dauer pheromone', produced by all worms. We suggest that the production of 'dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that 'dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.

Schaeffer JM et al. (1990) J Antibiot (Tokyo) "Cochlioquinone A, a nematocidal agent which competes for specific [3H]ivermectin binding sites."

Williamson JM, Schaeffer JM, Bergstrom AR, Liesch JM, Goetz MA, Frazier EG

[J Antibiot (Tokyo), 1990]

Cochlioquinone A, isolated from the fungus Helminthosporium sativum, was found to have nematocidal activity. Cochlioquinone A is a competitive inhibitor of specific [3H]ivermectin binding suggesting that cochlioquinone A and ivermectin interact with the same membrane receptor.

Desta IT et al. (2016) J Lab Autom "Detecting and Trapping of a Single C. elegans Worm in a Microfluidic Chip for Automated Microplate Dispensing."

Giakoumidis N, Mustafa N, AlGharibeh N, Orozaliev A, Al-Sharif A, Song YA, Desta IT, Gunsalus KC

[J Lab Autom, 2016]

Microfluidic devices offer new technical possibilities for a precise manipulation of Caenorhabditis elegans due to the comparable length scale. C. elegans is a small, free-living nematode worm that is a popular model system for genetic, genomic, and high-throughput experimental studies of animal development and neurobiology. In this paper, we demonstrate a microfluidic system in polydimethylsiloxane (PDMS) for dispensing of a single C. elegans worm into a 96-well plate. It consists of two PDMS layers, a flow and a control layer. Using five microfluidic pneumatic valves in the control layer, a single worm is trapped upon optical detection with a pair of optical fibers integrated perpendicular to the constriction channel and then dispensed into a microplate well with a dispensing tip attached to a robotic handling system. Due to its simple design and facile fabrication, we expect that our microfluidic chip can be expanded to a multiplexed dispensation system of C. elegans worms for high-throughput drug screening.

Ailion M et al. (2017) Curr Biol "Genetics: Master Regulator or Master of Disguise?"

Malik HS, Ailion M

[Curr Biol, 2017]

The pha-1 gene of Caenorhabditis elegans was originally heralded as a master regulator of organ differentiation. A new study suggests instead that pha-1 actually serves no role in development and instead is a component of a selfish genetic element.

Gokul G et al. (2020) Curr Biol "Extracellular Proteostasis: Laying Siege to Pathogens."

Singh J, Gokul G

[Curr Biol, 2020]

How protein homeostasis is maintained in the extracellular space remains poorly studied. A recent study employed a Caenorhabditis elegans model to carry out a systematic analysis of the extracellular proteostasis network and uncovered its role in combating a pathogenic attack.

Shi W et al. (2008) Lab Chip "Droplet-based microfluidic system for individual Caenorhabditis elegans assay."

Shi W, Lin B, Ye N, Qin J

[Lab Chip, 2008]

A droplet-based microfluidic system integrating a droplet generator and a droplet trap array is described for encapsulating individual Caenorhabditis elegans into a parallel series of droplets, enabling characterization of the worm behavior in response to neurotoxin at single-animal resolution.