Home WakeSpace Scholarship › Electronic Theses and Dissertations

MECHANISMS OF CARBON DIOXIDE DETECTION IN THE EARTHWORM EISENIA HORTENSIS

Electronic Theses and Dissertations

Item Files

Item Details

abstract
Carbon dioxide (CO2) is a critical biological signal, which, as a byproduct of respiration, often indicates the presence of other living organisms. The earthworm Eisenia hortensis lives in subterranean burrows containing high levels of CO2 and respires through its skin. Despite the ecological and agricultural importance of earthworms, relatively little is known about how they make decisions in their environment, including their response to elevated levels of CO2. Because we hypothesized that Transient Receptor Potential channel TRPA1 may be involved in CO2 detection in this species, this investigation involved both behavioral assays designed to gauge responses to CO2, and molecular investigations of TRPA1 channels. Because CO2 is noxious at high concentrations, we designed an assay, the exudate assay, to examine CO2 aversion in this species. In the exudate assay, we placed an earthworm in a sealed container and exposed it to varying concentrations of CO2 for one minute, and the amount of exudate secreted in that time was recorded. As earthworms secrete exudate in response to noxious stimuli, we hypothesized that the amount of exudate produced is proportional to the amount of irritation. We repeated these experiments after treatment with several blockers for molecules with potential involvement in CO2 detection, including carbonic anhydrases, guanylate cyclase, TRPA1 channels, acid sensing ion channels, and OTOP channels. Additionally, we attempted sequencing of the TRPA1 gene and utilized qPCR to evaluate the anatomical profile of TRPA1 gene expression in the earthworm. We found that earthworms secreted significantly more exudate in response to CO2 in a dosage-dependent manner, and that this response was muted by the general carbonic anhydrase inhibitor, acetazolamide; the calcium channel blocker, ruthenium red; the sodium channel blocker, amiloride; and ZnCl2. These data provide preliminary evidence of the role of carbonic anhydrase and ASICs in earthworm CO2 detection, and contribute to our understanding of how earthworms detect and react to their environment.
subject
Carbon Dioxide
Carbonic Anhydrase
Chemical Senses
Earthworm
Mucus
TRPA1
contributor
Smith, Emily Jordan (author)
Silver, Wayne L (committee chair)
Johnson, Erik C (committee member)
Saunders, Cecil J (committee member)
date
2021-06-03T08:36:13Z (accessioned)
2021 (issued)
degree
Biology (discipline)
2021-12-02 (liftdate)
embargo
2021-12-02 (terms)
identifier
http://hdl.handle.net/10339/98823 (uri)
language
en (iso)
publisher
Wake Forest University
title
MECHANISMS OF CARBON DIOXIDE DETECTION IN THE EARTHWORM EISENIA HORTENSIS
type
Thesis

Usage Statistics