A microfluidic phenotype analysis system reveals function of sensory and dopaminergic neuron signaling inC. eleganselectrotactic swimming behavior

Abstract

The nematode (worm) C. elegans is a leading multicellular animal model to study neuronal-basis of behavior. Worms respond to a wide range of stimuli and exhibit characteristic movement patterns. Here we describe the use of a microfluidics setup to probe neuronal activity that relies on the innate response of C. elegans to swim toward the cathode in the presence of a DC electric field (termed “electrotaxis”). Using this setup, we examined mutants affecting sensory and dopaminergic neurons and found that their electrotactic responses were defective. Such animals moved with reduced speed (35–80% slower than controls) with intermittent pauses, abnormal turning and slower body bends. A similar phenotype was observed in worms treated with neurotoxins 6-OHDA (6- hydroxy dopamine), MPTP (1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine) and rotenone (20–60% slower). We also found that neurotoxin effects could be suppressed by pre-exposing worms to a known neuroprotective compound acetaminophen. Collectively, these results show that microfluidic electrotaxis can identify alterations in dopamine and amphid neuronal signaling based on swimming responses of C. elegans. Further characterization has revealed that the electrotactic swimming response is highly sensitive and reliable in detecting neuronal abnormalities. Thus, our microfluidics setup could be used to dissect neuronal function and toxin-induced neurodegeneration. Among other applications, the setup promises to facilitate genetic and chemical screenings to identify factors that mediate neuronal signaling and neuroprotection.

An automated microfluidic system for screening Caenorhabditis elegans behaviors using electrotaxis

“…6(a), dat-1 swam more slowly than wild type as expected. 25,28 Similarly, in Fig. 6(b), the bending frequency of dat-1 is lower than wild type.…”

“…6(c), dat-1 has a longer turning time than wild type which as been reported earlier. 25 From Figs. 6(a)-6(c), it can be seen that dat-1 is more muted in response to electric fields than wild type.…”

“…[15][16][17][18][19][20][21][22] In previous work from our group, we designed a simple microfluidic device to examine the swimming behaviors of C. elegans under electric fields, termed electrotaxis, and demonstrated that changes in movement are reliable indicators of neurodegeneration and harmful effects of toxic chemicals on C. elegans health. [23][24][25] However, the inherent manual operation of the devices makes the screening process labor intensive and time consuming, which limits largely the practical application of the method. [23][24][25] In order to enable widespread use of the electrotactic assay, we have addressed the current limitations and developed an entirely new automated microfluidic system, which can perform electrotaxis assay for a batch of worms, without human intervention, one worm at a time while substantially increasing the throughput of analysis.…”

“…[23][24][25] However, the inherent manual operation of the devices makes the screening process labor intensive and time consuming, which limits largely the practical application of the method. [23][24][25] In order to enable widespread use of the electrotactic assay, we have addressed the current limitations and developed an entirely new automated microfluidic system, which can perform electrotaxis assay for a batch of worms, without human intervention, one worm at a time while substantially increasing the throughput of analysis. This system can load, isolate, perform electrotaxis assay, and flush C. elegans in a computer-controlled sequence.…”

Sensitivity of Planaria to Weak, Patterned Electric Current and the Subsequent Correlative Interactions with Fluctuations in the Intensity of the Magnetic Field of Earth

“…This indicates that when the electric field was on, an additional 14% of flatworms made contact with the electrode. Electrotaxis has been demonstrated many times in C. elegans [27][28][29]; however, this may be the first time, or one of the first times, that it has been demonstrated in planaria.…”