A Device to Measure the Propulsive Power of Nematodes

A Device to Measure the Propulsive Power of Nematodes

Abstract

The nematodes Caenorhabditis (C.) elegans is often used as model biological system to study the mechanics of swimming, genetic basis of behavior, disease-progression, and aging, as well as to develop new therapies and screen drugs. On occasion, it is desirable to quantify the nematode’s muscle power as a function of mutation, age, food supply, disease progression, drugs, and other environmental conditions. In the fluid dynamics video, we present a microfluidic device to measure the propulsive power of nematodes. The device consists of a tapered conduit filled with aqueous solution. The conduit is subjected to a DC electric field with the negative pole at the narrow end and to pressure-driven flow directed from the narrow end. The nematode is inserted at the conduit’s wide end. Directed by the electric field (through electrotaxis [1] ), the nematode swims deliberately upstream toward the negative pole of the DC field. As the conduit narrows, the average fluid velocity and the drag force on the nematode increase. Eventually, the nematode arrives at an equilibrium position, at which its propulsive force balances the viscous drag force induced by the adverse flow. Swimming gait, amplitude, and frequency of worms as functions of position along the conduit were obtained using a custom Matlab program that we have developed. The swimming amplitude and frequency were found to be nearly independent of the width of the conduit. The equilibrium position of different animals, with similar body lengths, was measured as a function of the flow rate. The flow field around the nematode was obtained by direct numerical simulations with the experimentally imaged gait and the tapered geometry of the conduit as boundary conditions. The flow field generated by a swimming worm is similar to the one induced by two pairs of counter rotating rotors. Equilibrium positions under different flow rates were identified by finding the positions at which the horizontal component of the total force exerted on the worm body vanishes. The theoretically predicted equilibrium positions were compared and favorably agreed with the experimental data. The nematode’s propulsive power was calculated by integrating the product of velocity and total stress over the worm’s body surface. The device is useful to retain the nematodes at a nearly fixed position for prolonged observations of active animals under a microscope, to keep the nematode exercising, and to estimate the nematode’s power consumption based on the conduit’s width at the equilibrium position.

References

  1. P. Rezai, A. Siddiqui, P. R. Selvaganapathy and B. P. Gupta, “Electrotaxis of Caenorhabditis elegans in A Microfluidic Environment,” Lab Chip, 2010, 10, 220-226.
Comments 0
Request Comment
You are adding the first comment!
How to quickly get a good reply:
  • Give credit where it’s due by listing out the positive aspects of a paper before getting into which changes should be made.
  • Be specific in your critique, and provide supporting evidence with appropriate references to substantiate general statements.
  • Your comment should inspire ideas to flow and help the author improves the paper.

The better we are at sharing our knowledge with each other, the faster we move forward.
""
The feedback must be of minumum 40 characters
Add comment
Cancel
Loading ...
75769
This is a comment super asjknd jkasnjk adsnkj
Upvote
Downvote
""
The feedback must be of minumum 40 characters
The feedback must be of minumum 40 characters
Submit
Cancel

You are asking your first question!
How to quickly get a good answer:
  • Keep your question short and to the point
  • Check for grammar or spelling errors.
  • Phrase it like a question
Test
Test description