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Biological Clock Behavior in Earthworms Measured by Near-Infrared Fluorescence

Primary Investigators:
Carl Johnson
 
Brief Description of Project:
To unearth and re-investigate a classical problem in animal behavior inspired by pioneering but preliminary work of Charles Darwin. Darwin made observations on the above-ground day/night behavior of earthworms, but was unable to determine what was happening with earthworm behavior after the worms re-entered the soil. There has been practically no further work on this problem since the publication of Darwin's book on this topic in 1881. This is a more difficult problem than it may appear because studying subterranean animals without disturbing their natural habitat has received little attention despite the importance of their underground activity. We propose to apply new state-of-the-art techniques to this problem while simultaneously providing the first data on biological clock (circadian rhythm) behavior in earthworms.

Desired Qualifications:
A bright, hard-working student in BME or BSci who is interested in trying a number of new approaches to assess the locomotor activity and vertical migration behaviors of earthworms. No special experience is necessary, although familiarity with computer data analyses would be useful.
 
Nature of Supervision:
The student will alternate between the laboratories of PIs Johnson and Mahadevan-Jansen. In Dr. Johnson's lab, the student will learn time-dependent image analysis methods to detect earthworm movement from one timepoint to the next. In Dr. Mahadevan-Jansen's lab, the student will learn and manipulate equipment in the FEL to acquire near-infrared images with and without "speckle" enhancers.
 
A Brief Research Plan (period is for 10 weeks):
We will take advantage of state-of-the-art near-infrared methodology pioneered by Dr. Mahadevan-Jansen to image earthworms in thick soil samples. Near-IR will be used because earthworms are blind to this range of the electromagnetic spectrum. In thick soil samples, the earthworms will be able to behave naturally and measurements taken of both their total activity (assessed by timepoint-to-timepoint changes in position) and vertical migration (assessed by movement on the surface of the soil as compared with in the depth of the soil). "Speckle analysis" will be implemented if enhanced sensitivity/contrast appears to be warranted after preliminary measurements. Once an optimal technology is in place, the earthworm behavior under different light/dark conditions and temperatures will be determined to demonstrate whether or not the earthworms exhibit circadian (daily) rhythmicity. Remarkably, the possibility that earthworms have a circadian clock is not known, in spite of Darwin's interest in these creatures long ago. Knowing whether earthworms have circadian rhythms or not will open a new realm of time-dependent biology in the subterranean niche. This project can be accomplished within the 10-week time frame of the summer session.
 
Number of Open Slots: 1
 
Contact Information:
Name: Carl Johnson
Department: Biological Sciences
Email: carl.h.johnson@vanderbilt.edu