Neuronal Morphology and Synapse Count in the Nematode Worm

Friedman, Robert M.

doi:10.3389/fncom.2019.00074

Cited by 2 publications

(1 citation statement)

References 63 publications

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“…Compared to other popular non-animal organismal models, namely nematodes, fruit flies, and developing zebrafish, D. japonica has unique advantages as a model system for OP studies. For example, nematodes have low neural complexity with only 302 neurons (Friedman 2019), fruit flies have negligible PON1 activity (Healy et al 1991), and developing zebrafish cannot bioactivate OPs before 3 days post fertilization (Yang et al 2011). Thus, OP pharmacodynamics and multi-OP interactions in these alternative models may not be representative of human exposure.…”

Section: Japonica Has Unique Strengths As a Non-animal Hts Model For ...mentioning

confidence: 99%

Bioactivation and detoxification of organophosphorus pesticides in freshwater planarians shares similarities with humans

et al. 2022

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Organophosphorus pesticides (OPs) are a chemically diverse class of insecticides that inhibit acetylcholinesterase (AChE). Many OPs require bioactivation to their active oxon form via cytochrome P450 to effectively inhibit AChE. OP toxicity can be mitigated by detoxification reactions performed by carboxylesterase and paraoxonase. The relative extent of bioactivation to detoxification varies among individuals and between species, leading to differential susceptibility to OP toxicity. Because of these species differences, it is imperative to characterize OP metabolism in model systems used to assess OP toxicity to adequately evaluate potential human hazard. We have shown that the asexual freshwater planarian Dugesia japonica is a suitable model to assess OP neurotoxicity and developmental neurotoxicity via rapid, automated testing of adult and developing organisms in parallel using morphological and behavioral endpoints. D. japonica has two cholinesterase enzymes with intermediate properties between AChE and butyrylcholinesterase that are sensitive to OP inhibition. Here, we demonstrate that this planarian contains the major OP metabolic machinery to be a relevant model for OP neurotoxicity studies. Adult and regenerating D. japonica can bioactivate chlorpyrifos and diazinon into their respective oxons. Significant AChE inhibition was only observed after in vivo metabolic activation but not when the parent OPs were directly added to planarian homogenate. Additionally, we found that D. japonica has both carboxylesterase and paraoxonase activity. Using specific chemical inhibitors, we show that carboxylesterase activity is distinct from cholinesterase activity. Taken together, these results further support the use of D. japonica for OP toxicity studies.

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Section: Japonica Has Unique Strengths As a Non-animal Hts Model For ...mentioning

confidence: 99%