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BackgroundIn all organisms, the innate immune system defends against pathogens through basal expression of molecules that provide critical barriers to invasion and inducible expression of effectors that combat infection. The adenosine deaminase that act on RNA (ADAR) family of RNA binding proteins has been reported to influence innate immunity in metazoans. However, studies on the susceptibility of ADAR mutant animals to infection are largely lacking.ResultsHere, by analyzingadr-1andadr-2null mutants in well-established slow-killing assays, we find that bothCaenorhabditis elegansADARs are important for organismal survival to gram-negative and gram-positive bacteria, all of which are pathogenic to humans. Furthermore, our high-throughput sequencing and genetic analysis reveal that ADR-1 and ADR-2 function in the same pathway to regulate collagen expression. Consistent with this finding, our scanning electron microscopy studies indicateadr-1;adr-2mutant animals also have altered cuticle morphology prior to pathogen exposure.ConclusionsOur data uncover a critical role of theC. elegansADAR family of RNA binding proteins in promoting cuticular collagen expression, which represents a new post-transcriptional regulatory node that influences the extracellular matrix. In addition, we provide the first evidence that ADAR mutant animals have altered susceptibility to infection with several opportunistic human pathogens, suggesting a broader role of ADARs in altering physical barriers to infection to influence innate immunity.

Identifying genetic variants associated with nicotine-motivated behavioral traits is an important strategy to understand the fundamental mechanisms underpinning smoking and tobacco abuse. For suitable emulation of behavioral phenotype with the full advantage of this invertebrate model, we newly established a worm model of nicotine seeking by Conditioned Cue Preference (CCP). We demonstrated that C. elegans also exhibited pivotal features of nicotine-motivated behaviors as in mammals. First, we identified the nicotine-elicited cue preference is mediated by nicotinic acetylcholine receptors in worms. Additionally, we exhibited dopamine is also required for the development of CCP. Subsequently, we identified the nAChRs subunits associated with the facilitation of nicotine preference. Accordingly, we validated human GWAS candidates associated with nicotine dependence involved in the role of those nAChR subunits. we addressed the cross-species functional validation to determine the GWAS candidate genes have authentic roles in nicotine seeking associated with tobacco abuse. The loss of function strain of CACNA2D3 orthologue, calcium voltage-gated channel auxiliary subunit alpha2delta 3, was tested for CCP. We also tested the knock-out (KO) strain of the CACNA2D2 orthologue, calcium voltage-gated channel auxiliary subunit alpha2delta 2, which is closely related to CACNA2D3 in the same family and shared the human smoking phenotypes. Our orthogonal test suggests the functional conservation of the α2δ subunit of calcium channel in nicotine motivated behavior.

An improved understanding of the molecular basis of alcohol seeking despite the catastrophic consequences of alcohol abuse is likely to enrich our treatments for Alcohol Use Disorders (AUD) and comorbidities. The compulsive seeking is characterized by an imbalance between the superior drive to substance and disruption in control of substance use. To model the development of compulsive engagement of alcohol seeking, we exploit two distinct behavioral programs of C. elegans in conflict, ethanol preference and avoidance of aversive stimulus, simultaneously. We demonstrate that C. elegans exhibited the recapitulation of the pivotal features of compulsive alcohol seeking in mammals, which are repeated attempts, endurance, and finally aversion-resistant ethanol seeking. We find that the neuropeptide signaling via SEB-3, CRF receptor-like GPCR, facilitates the development of ethanol preference and compels animals to seek ethanol compulsively. Furthermore, our functional genomic approach and behavioral elucidation suggest the interaction between neuropeptidergic signaling, SEB-3 and TKR-1, Neurokinin receptor orthologue, to progress compulsive ethanol seeking behavior.

The higher susceptibility of high glucose fed C. elegans to Monocrotophos (MCP, an organophosphorus insecticide) - induced dopaminergic (DA) neuronal degeneration was recently demonstrated. Employing this acute exposure model, the impact of MCP on DA degeneration among worms of two age groups (8 and 13 d old) fed control (CO) and high glucose (GF) diet with specific focus on phenotypic alterations, oxidative impairments and associated molecular perturbations employing both wild (N2) and transgenic strains(BZ555 and NL5901) was investigated. In general, 13 d worms exhibited higher susceptibility to MCP intoxication compared to 8 d old worms. Further, MCP-exposure caused an enhanced degree of DA degeneration among glucose fed (GF) worms as evidenced by lower chemotaxis index, reduced long-term memory and increased nonanone repulsion. Biochemical analysis of 13 d GF worms also revealed a significant increase in ROS, protein carbonyls and reduced ADP/ATP ratio. Interestingly, marked increase in degeneration of dopaminergic neurons and increased in α-synuclein content was evident among 13 d GF worms exposed to MCP. Significant alterations in the mRNA expression levels of daf-2, age-1, sir 2.1 and aak-2 among 13 d GF worms was evident. Collectively these findings suggest that high intake of glucose diet aggravates MCP associated dopaminergic neuronal degeneration and the impact of increasing age under such a condition. Moreover it provides an experimental paradigm to explore the molecular targets and mechanism/s underlying the possible relationship between insecticide exposure-associated dopaminergic degeneration in humans under hyperglycemic conditions.

The present study aimed to obtain insights into the mechanism(s) by which glucose-rich diet aggravates monocrotophos (MCP)-induced dopaminergic neuronal dysfunction in Caenorhabditis elegans. In this study, we exposed three different strains of worms (wild-type N2, CB1112 (cat-2(e1112)II, tyrosine hydroxylase-deficient mutant, catecholamine absent) and the transgenic BZ555 (egls1-dat-1p::green fluorescent protein [GFP]) (in which bright GFP is tagged to the dopamine neuronal soma and processes) grown and maintained in normal nematode growth medium or 2% glucose enriched-nematode growth medium to MCP (0.75 mm) for 48 h. After the exposure, dopamine-mediated behaviors such as repulsion to nonanone, chemotaxis index and basal slowing response were determined in worms. Dopamine, 3,4-dihydroxy phenyl acetic acid and homovanillic acid content were quantified in N2 worms. The extent of neurodegeneration was visualized and quantified in dat-1::GFP worms. Basal slowing response study clearly indicated that cat-2 worms exposed to MCP and glucose were less affected compared to N2 of the same treatment. Learning and memory were affected by MCP and glucose. While MCP-treated worms showed lesser repulsion to nonanone compared to control worms, MCP-treated, glucose-fed worms showed a greater reduction in repulsion to nonanone. Further, MCP-treated, glucose-fed worms exhibited a marked reduction in dopamine content and an increase in 3,4-dihydroxy phenyl acetic acid and homovanillic acid levels compared to that in control. Dat-1::GFP showed a significant degeneration of dopaminergic neurons when exposed to glucose and MCP. Thus, our results clearly demonstrate that glucose-rich diet aggravates the dopaminergic neuronal dysfunction induced by MCP in C. elegans. Copyright © 2016 John Wiley & Sons, Ltd.

The objectives of this investigation were to establish the propensity of the chitooligomers (COS) to ameliorate neurodegeneration and oxidative stress in Caenorhabditis elegans induced by an organophosphorus insecticide, Monocrotophos (MCP). COS was prepared from α-chitosan by the enzymatic method using chitosanase and characterized by HPLC and electron spray ionization-TOF-(ESI-TOF)-MS. We exposed age synchronized L4 C. elegans worms (both wild type N2 and transgenic strain BZ555 (Pdat-1:GFP) to sublethal concentration of MCP (0.75 mM) for 24 h in the presence or absence of COS (0.2 mM). The neuroprotective effect of COS was examined in N2 worms in terms of brood size, lifespan, egg laying, dopamine content, acetylcholinesterase and carboxylesterase activity and by direct visualization and quantification of degeneration of dopaminergic neurons in BZ555. Exposure to COS extended lifespan, normalized egg laying, increased brood size, decreased the dopaminergic neurodegeneration, increased the dopamine content and increased AChE and carboxylesterase activity in C. elegans treated with MCP. COS induced a significant decrease in reactive oxygen species and increased the reduced glutathione level as well as increased superoxide dismutase and catalase activity. Our findings demonstrate that COS significantly inhibits the dopaminergic neurodegeneration and associated physiological alterations induced by MCP in C. elegans by attenuating the oxidative stress as well.

Curcumin (CUR), the principal curcuminoid and the “yellow coloring matter” of turmeric, has been demonstrated to exhibit protective activity against various neurologic diseases. Owing to its hydrophobic in nature, CUR is insoluble in water, and its poor solubility in aqueous solution remains a major barrier in its bioavailability and clinical efficacy. In view of this, in the present study, we rendered the CUR hydrophilic by making an ‘inclusion compound’ with gamma cyclodextrin (γCD) and evaluated its neuroprotective efficacy by employing the model system Caenorhabditis elegans. Both wild-type and transgenic strain of C. elegans [expressing green fluorescent protein (GFP) specifically in the dopaminergic neurons [BZ555 (Pdat-1: GFP] were treated with either the well-known neurotoxin, 6-hydroxydopamine (6-OHDA) or Monocrotophos (MCP), a neurotoxic insecticide. We examined the ameliorative effect of CUR on phenotype (in terms of locomotion), reproductive parameters (brood size, egg-laying) and longevity. Further, neurotoxicity was assessed by monitoring neurodegeneration of dopaminergic neurons and acetylcholinesterase activity. We found that CUR treatment marginally increased egg laying, brood size and the survival (by 3d). Interestingly, it also significantly decreased the dopaminergic neurodegeneration with a marginal restoration of acetylcholinesterase activity among worms exposed to either OHDA or MCP. Our findings provide evidence for the potential of CUR to ameliorate neuronal dysfunction in the worm model and suggest its use as a therapeutic molecule against PD.

Several studies have demonstrated that high glucose feeding induced oxidative stress and apoptosis thereby affecting growth, fertility, aging and lifespan in Caenorhabditis elegans. Earlier studies from our laboratory had clearly established the propensity of monocrotophos, an OPI to alter the physiological and behavioral responses of C. elegans. The present study was aimed to investigate the effect of monocrotophos (MCP) on physiological/behavioral and biochemical responses in C. elegans that were maintained on high glucose diet. We exposed the worms through development to high glucose diet (2%) and then treated with sublethal concentrations of MCP (0.5, 0.75, 1.5mM). We measured the behavioral responses in terms of locomotion, physiological responses in terms of egg laying, brood size, lifespan; morphological alterations; and biochemical responses including glucose content. The worms exposed from egg stage through development to high glucose diet showed enhanced toxic outcome of MCP in terms of physiological, behavioral and biochemical responses. Our studies showed that C. elegans is a good model to study glucose-OPI interactive neurotoxicity since all the responses could be studied at ease in this organism and the outcome could be well extrapolated to those that one would expect in higher animals.