Hiebert T et al. (2017) MicroPubl Biol "Reduced pharyngeal pumping rates observed in tph-1 mutants using microfluidic electropharyngeogram (EPG) recordings."

Hiebert T, McCormick K, Chicas-Cruz A

[MicroPubl Biol, 2017]

In Caenorhabditis elegans, serotonin (5-HT) activates and controls pharyngeal pumping in response to food (Horvitz et al., 1982; Sze et al., 2000; Song and Avery 2012). Tryptophan hydroxylase, the enzyme required for serotonin biosynthesis, is encoded by the gene tph-1. Worms with a tph-1 deletion mutation exhibit phenotypes associated with a lack of serotonin-signaling, including reduced pharyngeal pumping (Sze et al., 2000; Avery and Horvitz 1990; Song and Avery 2012). We used a microfluidic electropharyngeogram (EPG) recording platform (NemaMetrix) and associated software (NemAnalysis) to measure pharyngeal pumping in C. elegans tph-1 mutants in the presence of bacterial food (100 mg/ml E. coli OP50 in M9 buffer), following a 2-hr fasting period. Prior research has shown that a fasting period (e.g., 2-4-hr) induces elevated feeding rates for worms upon re-introduction to bacterial food (Lemieux and Ashrafi 2015). We chose to measure pharyngeal pumping during this elevated feeding phase due to our hypothesis that tph-1 animals would exhibit lower pumping rates than control worms. Pumping was recorded for 2-minute durations over three independent trials (total N2 n = 90; tph-1 n = 92). C. elegans tph-1 mutants exhibited significantly lower pharyngeal pumping rates than N2 control animals (A, N2 = 3.46 0.19 Hz; tph-1 = 0.89 0.10 Hz; mean SEM; *** p < 0.0001, 2-tailed students t-test). Pumping frequency data were pooled in A; see B for a comparison of each experimental trial.

Titanji VP et al. (1988) Parasitol Res "Studies on glucose-6-phosphate dehydrogenase from the human parasite, Onchocerca volvulus."

Tchoupe JR, Muluh JP, Titanji VP

[Parasitol Res, 1988]

Glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) was partially purified from the extracts of adult Onchocerca volvulus by affinity chromatography on 2'5'ADP-Sepharose-4B. Kinetic studies revealed a typical bell-shaped pH profile with an optimum lying between pH 7.3 and 7.8. The apparent Km for glucose-6-phosphate was 5.66 x 10(-5) M, whereas that for NADP was 2.17 x 10(-6) M. Suramin, a filaricidal drug, inhibited the enzyme competitively with respect to NADP as a substrate: the apparent Ki values were 2.23 x 10(-6) M and 4.21 x 10(-7) M, respectively, for the crude and purified enzyme preparations. Glucose-6-phosphate dehydrogenase therefore, could be one of the targets of suramin in vivo.

Wolf, Trevor et al. (2020) MicroPubl Biol

Wolf, Trevor, Perez, Ariana, Harris, Gareth

[MicroPubl Biol, 2020]

Sensation of environmental cues and decisions made as a result of processing of specific sensory cues underlies a myriad of behavioral responses that control every-day life decisions and ultimately survival in many organisms. Despite the appreciation that organisms can sense, process, and translate sensory cues into a behavioral response, the neural mechanisms and molecules that mediate these behaviors are still unclear. Neurotransmitters, such as glutamate, have been implicated in a variety of sensory-dependent behavioral responses, including olfaction, nociception, mechanosensation, and gustation (Mugnaini et al., 1984, Wendy et al., 2013, Daghfous et al., 2018). Despite understanding the importance of glutamate signaling in sensation and translation of contextual cues on behavior, the molecular mechanisms underlying how glutamatergic transmission influences sensory behavior is not fully understood. The nematode, C. elegans, is able to sense a variety of sensory cues. These types of sensory-dependent behavioral responses are mediated through olfactory, gustatory, mechanosensory and aerotactic circuits of the worm (Lans and Jansen, 2004, Milward et al., 2011, Bretscher et al., 2011, Kodama-Namba et al., 2013, Ghosh et al., 2017). Odor guided behavior toward attractants, such as, food cues requires neurotransmitters, that include, glutamate (Chalasani et al., 2007, Chalasani et al., 2010). More specifically, once on a food source, wild type N2 hermaphrodites will generally be retained on a food source (Shtonda and Avery, 2006, Milward et al., 2011, Harris et al., 2019). The types, quality, pathogenicity, and perception of food can modulate food recognition, food leaving rates, and overall navigational strategies towards food (Zhang et al., 2005, Shtonda and Avery, 2006; Ollofsson et al., 2014). These types of behaviors are based on detection of environmental cues, including oxygen, metabolites, pheromones, and odors. Food leaving behaviors have been shown to be influenced by a number of neuronal signals (Shtonda and Avery, 2006, Bendesky et al., 2011, Ollofsson et al., 2014, Meisel et al., 2014, Hao et al., 2018).

Furuta T et al. (2023) MicroPubl Biol "sart-3 functions to regulate germline sex determination in C. elegans ."

Arur S, Furuta T

[MicroPubl Biol, 2023]

<i>Caenorhabditis elegans</i> gene <i>sart-3</i> was first identified as the homolog of human SART3 ( S quamous cell carcinoma A ntigen R ecognized by T -cells 3). In humans, expression of SART3 is associated with squamous cell carcinoma, thus most of the studies focus on its potential role as a target of cancer immunotherapy (Shichijo et al. 1998; Yang et al. 1999). Furthermore, SART3 is also known as Tip110 (Liu et al. 2002; Whitmill et al. 2016) in the context of HIV virus host activation pathway. Despite these disease related studies, the molecular function of this protein was not revealed until the yeast homolog was identified as spliceosome U4/U6 snRNP recycling factor (Bell et al. 2002). The function of SART3 in development, however, remains unknown. Here we report that the <i>C. elegans</i> <i>sart-3</i> mutant hermaphrodites exhibit a Mog ( M asculinization O f the G ermline) phenotype in adulthood suggesting that <i>sart-3</i> normally functions to regulate the switch from spermatogenic to oogenic gametic sex.

Espinosa F et al. (2001) J Gen Physiol "Dynamic interaction of S5 and S6 during voltage-controlled gating in a potassium channel."

Joho RH, Fleischhauer R, Espinosa F, McMahon A

[J Gen Physiol, 2001]

A gain-of-function mutation in the Caenorhabditis elegans exp-2 K+-channel gene is caused by a cysteine-to-tyrosine change (C480Y) in the sixth transmembrane segment of the channel (Davis, M.W, R. Fleisch-hauer, J.A. Dent, R.H.Joho, and L. Avery. 1999. Science. 286:2501-2504). In contrast to wild-type EXP-2 channels, homotetrameric C480Y mutant channels are open even at - 160 mV, explaining the lethality of the homozygous mutant. We modeled the structure of EXP-2 on the 3-D scaffold of the K+ channel KcsA. In the C480Y mutant, tyrosine 480 protrudes from S6 to near S5, suggesting that the bulky side chain may provide steric hindrance to the rotation of S6 that has been proposed to accompany the open-closed state transitions (Perozo, E., D.M. Cortes, and L.G. Cuello. 1999. Science. 285:73-78). We tested the hypothesis that only small side chains at position 480 allow the channel to close, but that bulky side chains trap the channel in the open state. Mutants with small side chain substitutions (Gly and Ser) behave like wild type; in contrast, bulky side chain substitutions (Trp, Phe, Leu, Ile, Val, and His) generate channels that conduct K+ ions at potentials as negative as - 120 mV. The side chain at position 480 in S6 in the pore model is close to and may interact With a conserved glycine (G421) in S5. Replacement of G421 with bulky side chains also leads to channels that are trapped in an active state, suggesting that S5 and S6 interact with each other during voltage-dependent open-closed state transitions, and that bulky side chains prevent the dynamic changes necessary for permanent channel closing. Single-channel recordings show that mutant channels open frequently at negative membrane potentials indicating that they fail to reach long-lasting, i.e., stable, closed states. Our data support a "two-gate model" with a pore gate responsible for the brief, voltage-independent openings and a separately located, voltage-activated gate (Liu, Y, and R.H.Joho. 1998. Pflugers Arch. 435: 654-661).

Schertzinger G et al. (2017) Environ Pollut "Assessment of sublethal endpoints after chronic exposure of the nematode Caenorhabditis elegans to palladium, platinum and rhodium."

Schertzinger G, Zimmermann S, Grabner D, Sures B

[Environ Pollut, 2017]

The aim of this study was to investigate chronic effects of the platinum-group elements (PGE) palladium (Pd), platinum (Pt) and rhodium (Rh) on the nematode Caenorhabditis elegans. Aquatic toxicity testing was carried out according to ISO 10872 by determining 96h EC50 values for sublethal endpoints, including growth, fertility and reproduction. Single PGE standard solutions were used as metal source. Based on the EC50 values for Pt, reproduction (96h EC50=497g/L) was the most sensitive endpoint followed by fertility (96h EC50=726g/L) and growth (96h EC50=808g/L). For Pd, no precise EC50 values could be calculated due to bell-shaped concentration response curves, but the 96h EC50 for reproduction ranged between 10 and 100g/L. Pd and Pt had effects on all endpoints. With raising element concentrations reproduction was inhibited first. At a certain concentration, fertility was also affected, which in turn had an additional effect on reproduction. Growth inhibition can also lead to a loss of fertility if the worms do not reach an appropriate body size to become fertile. Rhodium showed no inhibition of any endpoint between concentrations of 100 to 10,000g Rh/L. The results of this study allow the following order of PGE with respect to decreasing toxicity to C.elegans: Pd&gt;Pt"Rh.

Chen, Lili et al. (2020) MicroPubl Biol

Wang, Ya, Chen, Lili, Gao, Shangbang

[MicroPubl Biol, 2020]

The action potential (AP) is the basic signaling unit in various crucial physiological processing, for instance, in neurotransmission, muscle contraction, and glandular secretion (Koch, 1990). The classic model animal, Caenorhabditis elegans (or C. elegans), with a simple and compact nervous system, conservatively employs the calcium-mediated all-or-none APs for odor response in AWA olfactory neurons (Liu et al., 2018), as well as for muscle contraction in either body wall muscles (Gao and Zhen, 2011; Liu et al., 2011) and pharyngeal muscles (Davis et al., 1999). Plateau potentials were also observed in ASE and RMD neurons (Goodman et al., 1998; Mellem et al., 2008; Lockery et al., 2009; Lockery and Goodman, 2009), though the underlying roles in specific behavior are still elusive. Either in neurons or in muscles, the action potential firing is dependent on the excitatory pre-synaptic vesicles release. The minimum number of the presynaptic vesicles to elicit a single action potential in C. elegans has not been reported before. Here, by the combination of optogenetics with in-vivo patch clamping technology, we demonstrated that at least approximately 37 excitatory acetylcholinergic vesicles are required for the initiation of an action potential at post-synaptic body wall muscles.

Preston S et al. (2017) FASEB J "Deguelin exerts potent nematocidal activity via the mitochondrial respiratory chain."

Sternberg PW, Ansell BRE, Andrews KT, Nowell C, Chang BCH, Hofmann A, Crawford S, Korhonen PK, Baell J, Gijs MAM, Fisher GM, Young ND, Preston S, Mouchiroud L, Gasser RB, Jabbar A, Auwerx J, Davis RA, McGee SL, Cornaglia M

[FASEB J, 2017]

As a result of limited classes of anthelmintics and an over-reliance on chemical control, there is a great need to discover new compounds to combat drug resistance in parasitic nematodes. Here, we show that deguelin, a plant-derived rotenoid, selectively and potently inhibits the motility and development of nematodes, which supports its potential as a lead candidate for drug development. Furthermore, we demonstrate that deguelin treatment significantly increases gene transcription that is associated with energy metabolism, particularly oxidative phosphorylation and mito-ribosomal protein production before inhibiting motility. Mitochondrial tracking confirmed enhanced oxidative phosphorylation. In accordance, real-time measurements of oxidative phosphorylation in response to deguelin treatment demonstrated an immediate decrease in oxygen consumption in both parasitic (Haemonchus contortus) and free-living (Caenorhabditis elegans) nematodes. Consequently, we hypothesize that deguelin is exerting its toxic effect on nematodes as a modulator of oxidative phosphorylation. This study highlights the dynamic biologic response of multicellular organisms to deguelin perturbation.-Preston, S., Korhonen, P. K., Mouchiroud, L., Cornaglia, M., McGee, S. L., Young, N. D., Davis, R. A., Crawford, S., Nowell, C., Ansell, B. R. E., Fisher, G. M., Andrews, K. T., Chang, B. C. H., Gijs, M. A. M., Sternberg, P. W., Auwerx, J., Baell, J., Hofmann, A., Jabbar, A., Gasser, R. B. Deguelin exerts potent nematocidal activity via the mitochondrial respiratory chain.

Liu Q et al. (2006) J Biol Chem "Low conductance gap junctions mediate specific electrical coupling in body-wall muscle cells of Caenorhabditis elegans."

Gaier E, Wang ZW, Joshi J, Chen B, Liu Q

[J Biol Chem, 2006]

Invertebrate innexins and their mammalian homologues pannexins are gap junction proteins. Despite a large number of such proteins have been identified, few gap junctions that they form have been characterized with combined information of biophysical properties, coupling pattern, and molecular compositions. We adapted the dual whole-cell voltage clamp technique to in situ analysis of electrical coupling in C. elegans body-wall muscle. We found that body-wall muscle cells were electrically coupled in a highly organized and specific pattern. The coupling was characterized by small (350 pS or less) junctional conductance (Gj), which showed a bell-shaped relationship with junctional potential (Vj) but was independent of membrane potential (Vm). Injection of currents comparable to the junctional current (Ij) into body-wall muscle cells caused significant depolarization, suggesting important functional relevance. The innexin UNC-9 appeared to be a key component of the gap junctions. Both Myc- and GFP-tagged UNC-9 was localized to muscle intercellular junctions. Gj was greatly inhibited in unc-9(fc16), a putative null mutant. Specific inhibition of UNC-9 function in muscle cells reduced locomotion velocity. Despite UNC-9 expression in both motor neurons and body-wall muscle cells, analyses of miniature and evoked postsynaptic currents (mPSCs and ePSCs) in the unc-9 mutant showed normal neuromuscular transmission. These analyses provide a relatively detailed description of innexin-based gap junctions in a native tissue, and suggest that innexin-based small-conductance gap junctions can play an important role in processes such as locomotion.

Blacque OE et al. (2006) Mol Biol Cell "The WD repeat-containing protein IFTA-1 is required for retrograde intraflagellar transport."

Scholey JM, Mah AK, Inglis PN, Leroux MR, Li C, Ou G, Esmail MA, Baillie DL, Blacque OE

[Mol Biol Cell, 2006]

Monitoring Editor: Trisha Davis The assembly and maintenance of cilia requires intraflagellar transport (IFT), a microtubule-dependent bidirectional motility of multisubunit protein complexes along ciliary axonemes. Defects in IFT and the functions of motile or sensory cilia are associated with numerous human ailments, including polycystic kidney disease and Bardet-Biedl syndrome (BBS). Here, we identify a novel Caenorhabditis elegans IFT gene, ifta-1 (IFT-Associated gene 1), which encodes a WD-repeat containing protein with strong homology to a mammalian protein of unknown function. Both the C. elegans and human IFTA-1 proteins localize to the base of cilia, and in C. elegans, IFTA-1 can be observed to undergo IFT. IFTA-1 is required for the function and assembly of cilia, since a C. elegans ifta-1 mutant displays chemosensory abnormalities and shortened cilia with prominent ciliary accumulations of core IFT machinery components that are indicative of retrograde transport defects. Analyses of C. elegans IFTA-1 localization/motility along bbs mutant cilia, where anterograde IFT assemblies are destabilised, and in a che-11 IFT gene mutant, demonstrate that IFTA-1 is closely associated with the IFT particle A subcomplex, which is implicated in retrograde IFT. Taken together, our data indicates that IFTA-1 is a novel IFT protein that is required for retrograde transport along ciliary axonemes.