Popham JD et al. (1979) Nematologica "The use of osmium mixtures in localizing ions in C. elegans."

Webster JM, Popham JD

[Nematologica, 1979]

Electron microscopy of Caenorhabditis elegans fixed in an aqueous solution of osmium tetroxide mixed with potassium pyroantimonate, silver lactate or lead nitrate revealed the following. Calcium is localised in the median and basal layers of the cuticle, in the myofibrils of the body wall muscle, in mitochondria, and in intestinal cytosomes. Chloride ions are localised in the cortical zone of the cuticle along the apical membrane infoldings of the hypodermal cells and in the ground substance of the cytoplasm and vesicles of intestinal cells. Orthophosphate ions are localised in nucleoli and heterochromatin, in cytosomes of the intestinal cells, in foldings of the external membranes of the hypodermis, and in the intracristal space of mitochondria. Orthophosphates and/or sulphates surround the microvilli of intestinal cells. The results suggest that chloride ion regulation may occur in the hypodermal cells and intestinal cells rather than in the excretory tubules of C. elegans.

Popham JD et al. (1979) Canadian Journal of Zoology "Aspects of the fine structure of the dauer larva of the nematode C. elegans."

Popham JD, Webster JM

[Canadian Journal of Zoology, 1979]

Examination of the ultrastructure of the dauer larva of Caenorhabditis elegans showed that cells in the lateral cord and body wall muscle had irregular profiles, few Golgi bodies, and cisternae of endoplasmic reticulum, but they contained abundant lipid and glycogen. These cells and the esophageal cells had mitochondria in the condensed conformation. The intestinal lumen was small and the brush border was so compact that individual microvilli were difficult to discern. Intestinal cells had cytosomes with irregular profiles and unhomogeneous matrices. The striated layer was absent from the cuticle covering the lips and papillae. These ultrastructural features are correlated with the dauer larva's low metabolic rate, its resistance to toxic chemicals and to adverse environmental conditions, and its ability to detect food and to feed soon after exposure to a hospitable environment.

Popham JD et al. (1979) Environ Res "Cadmium toxicity in the free-living nematode, Caenorhabditis elegans."

Popham JD, Webster JM

[Environ Res, 1979]

The effect of cadmium on the fecundity, growth, and fine structure of the free-living nematode Caenorhabditis elegans was studied. High concentrations of cadmium significantly decreased the fecundity and growth of these organisms. Electron microscopy showed that cadmium modifies the structure of the mitochondria in the esophagus and intestine, causes the formation of inclusion bodies in the nucleus of esophageal cells, and alters the morphology of cytosomes in the intestinal cells. The results suggest that the decreased fecundity and growth of cadmium-exposed C. elegans may be due to cadmium interfering with nutrient uptake or assimilation or both.

Popham JD et al. (1982) Ecotoxicol Environ Saf "Ultrastructural changes in C. elegans (Nematoda) caused by toxic levels of mercury and silver."

Webster JM, Popham JD

[Ecotoxicol Environ Saf, 1982]

Mercury toxicity in Caenorhabditis elegans showed as lesions in esophageal muscles and intestinal cells and consisted of degradation of the cytoplasm and the formation of irregularly shaped cytosomes. Specimens intoxicated with silver showed changed cytosomes with a spongy matrix in the intestinal cells and ruffled membranes on the mitochondria of hypodermal cells. General ultrastructural responses reflecting a distress syndrome common to several heavy metals were also noted. The results are discussed with reference to the concept of using free-living nematodes to assist in the diagnosis of the causative toxic heavy metal in a complex.

Popham JD et al. (1978) Can J Zool "An alternative interpretation of the fine structure of the basal zone of the cuticle of the dauerlarva of the nematode Caenorhabditis elegans (Nematoda)."

Webster JM, Popham JD

[Can J Zool, 1978]

The fine structure of the basal zone of the cuticle of the dauerlarva of Caenorhabditis elegans was examined in order to help resolve controversies regarding its structure. The results show that the striated layer in the basal zone consists of two sets of laminae oriented at right angles to each other. One set of laminae consists of longitudinally oriented, alternately thick and thin, osmiophilic strips with the distance between similar strips measuring 19 nm. The other set of laminae consists only of thick strips spaced about 14.5 nm apart which are oriented circumferentially about the larva. It is speculated that the striated layer of the basal zone of the cuticle consists of blocks of protein separated by this apparent network of interconnecting osmiophilic laminae.

Moerman DG et al. (1979) International C. elegans Meeting "an analysis of the unc-22 region in C elegans: fine structure and suppression."

Popham JD, Baillie DL, Moerman DG

[International C. elegans Meeting, 1979]

Visentin C et al. (2017) Hum Mol Genet "Epigallocatechin-3-gallate and related phenol compounds redirect the amyloidogenic aggregation pathway of ataxin-3 towards non-toxic aggregates and prevent toxicity in neural cells and Caenorhabditis elegans animal model."

Natalello A, Regonesi ME, Gatta E, Pellistri F, Bonanomi M, Penco A, Relini A, Visentin C, Tortora P, Vertemara J, Airoldi C, De Gioia L

[Hum Mol Genet, 2017]

The protein ataxin-3 (ATX3) triggers an amyloid-related neurodegenerative disease when its polyglutamine stretch is expanded beyond a critical threshold. We formerly demonstrated that the polyphenol epigallocatechin-3-gallate (EGCG) could redirect amyloid aggregation of a full-length, expanded ATX3 (ATX3-Q55) towards non-toxic, soluble, SDS-resistant aggregates. Here, we have characterized other related phenol compounds, although smaller in size, i.e., (-)-epigallocatechin gallate (EGC), and gallic acid (GA). We analyzed the aggregation pattern of ATX3-Q55 and of the N-terminal globular Josephin domain (JD) by assessing the time course of the soluble protein, as well its structural features by FTIR and AFM, in the presence and the absence of the mentioned compounds. All of them redirected the aggregation pattern towards soluble, SDS-resistant aggregates. They also prevented the appearance of ordered side-chain hydrogen bonding in ATX3-Q55, which is the hallmark of polyQ-related amyloids. Molecular docking analyses on the JD highlighted three interacting regions, including the central, aggregation-prone one. All three compounds bound to each of them, although with different patterns. This might account for their capability to prevent amyloidogenesis. Saturation transfer difference NMR experiments also confirmed EGCG and EGC binding to monomeric JD. ATX3-Q55 pre-incubation with any of the three compound prevented its calcium-influx-mediated cytotoxicity towards neural cells. Finally, all the phenols significantly reduced toxicity in a transgenic Caenorhabditis elegans strain expressing an expanded ATX3. Overall, our results show that the three polyphenols act in a substantially similar manner. GA, however, might be more suitable for antiamyloid treatments due to its simpler structure and higher chemical stability.

Amigoni, L. et al. (2019) International Worm Meeting "Caenorhabditis elegans as a model for searching compounds capable of preventing Spinocerebellar Ataxia Type 3."

Bonanomi, M., Visentin, C., Sciandrone, B., Airoldi, C., Amigoni, L., Tortora, P., Regonesi, M.E., Natalello, A.

[International Worm Meeting, 2019]

Ataxin-3 (ATX3) is the protein that triggers the neurodegenerative disorder spinocerebellar ataxia type 3 (SCA3) when its polyglutamine stretch exceeds the critical length of 55 residues. This expansion results in misfolding and structural rearrangements, leading to aberrant interactions and the consequent formation of fibrillar amyloid-like aggregates. Currently, no effective treatment is available for SCA3 disease. In order to find natural compounds able to prevent ATX3 aggregation, we studied the effect of tetracycline (TET) and epigallocatechin-3-gallate (EGCG) on ATX3 fibrillogenesis. We displayed that TET increased the solubility of the different aggregated species, without affecting the secondary structures of the final aggregates. Otherwise, EGCG interfered with the early steps of aggregation, accelerating the Josephin Domain (JD) misfolding, and leading to the formation of off-pathway, non-amyloid, final aggregates. By NMR analyses, we proved that the different behavior could be related to the capability of the sole EGCG to bind the monomeric JD. Successively, among a small library of tetracycline, we identified methacycline (MET) as the most effective compound, which exerts the same mechanism of action of TET. The pharmacological efficacy of EGCG, TET and MET has been evaluated on a SCA3 C. elegans model and we demonstrated that all compounds induced a significant increase in mobility without extending the lifespan. MET was proven to be the most effective in relieving the locomotion defects. Even more remarkably, MET treatment also resulted in an ameliorated motility even in wild-type worms suggesting that MET fulfills its action via diverse mechanisms, besides interfering with amyloid aggregation. Furthermore, the drug did not significantly modify the life span in any of the strains investigated, which supports the expectation that it may be devoid of toxic effects in long-term administration.

JD Kormish et al. (1999) International C. elegans Meeting "A genetic screen for genes involved in gut development and differentiation"

JD McGhee, JD Kormish

[International C. elegans Meeting, 1999]

To investigate genes potentially involved in gut development and differentiation, we are developing a genetic screen for gut obstructed (gob) mutants. The gut specific elt-2 GATA factor appears necessary for correct gut cell development. elt-2 null mutants arrest as L1s with a blocked intestinal lumen and abnormal brush border (1). When elt-2 null mutants are fed on a mixture of fluorescent beads and Escherichia coli , the beads collect as a large "gob" in the posterior pharynx and anterior gut that can be easily detected under the dissecting microscope. We are now using this gut obstructed phenotype to screen for mutants that should potentially identify genes involved in gut development. Preliminary results of this screen are promising, as several candidates have already been isolated. 1) Fukushige T, Hawkins MG and McGhee JD (1998) Dev Biol 198(2):286-302

Meisel, Joshua et al. (2015) International Worm Meeting "Genetic Analysis of Neuronal Signaling Coupling Microbial Detection to the Induction of TGF-beta/DAF-7 Gene Expression in C. elegans."

Kim, Dennis, Meisel, Joshua

[International Worm Meeting, 2015]

Environmentally induced changes in neuronal gene expression are a critical feature underlying behavioral plasticity. We have previously shown that transcription of the neuromodulator TGF-beta/DAF-7 is rapidly activated in the ASJ chemosensory neuron pair in response to the pathogenic bacteria Pseudomonas aeruginosa and that this expression change promotes avoidance behavior (Meisel, JD et. al., Cell, 2014). Using a genetically encoded calcium indicator we have also shown that specific secondary metabolites produced by P. aeruginosa can activate the ASJ neurons. To further understand the molecular mechanisms and genetic pathways responsible for transducing an environmental sensory input into a transcriptional response we performed a forward genetic screen to identify genes necessary for the activation of daf-7 transcription in response to P. aeruginosa. We have identified conserved genes involved in G protein-coupled receptor signaling and calcium signaling that are required for daf-7 activation in the ASJ neuron pair. We have also identified mutants with constitutive daf-7 expression in the ASJ neurons when C. elegans are propagated on non-pathogenic E. coli. Analysis of neuronal calcium dynamics in these mutant backgrounds will provide insight into how sensory activity and calcium signaling are coupled to rapid changes in transcription that modulate behavior.