2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

studying a single receptor that responds vigorously to a presented banana: Or22a.
We performed calcium imaging recordings on the flies antenna by selectively
expressing the Ca2+ sensitive dye G-CaMP under the control of the Or22a promoter
using the GAL4/UAS expression system.
We found that five out of 15 components elicited a significant response when
presented alone at the concentration in which they naturally occur in banana. The
response strength towards one component (isopentyl-acetate) alone did not differ
from that to the full blend whereas the other four elicited significantly lower
responses. Thus for Or22a the single odorant isopentyl-acetate is equivalent to the
full bouquet, but how do the other components contribute?
Thus, even adding good ligands did not increase the isopentyl-acetate odor response,
indicating that hypoadditive mixture effects where taking place. In order to analyze
the underlying mechanism, we characterized the full dose-response curves for
mixtures and components, and modeled different mixture-interaction scenarios.
These models show that the observed mixture effects arise from syntopic interaction
at a single interaction site with the receptor Or22a. While we cannot exclude
intracellular interactions or multiple interaction sites, they are not necessary to
explain the full extent of the effects that we observed. In addition, we found that
syntopic interaction is ideally suited to ensure a stable response across a range of
mixture concentration.
����162 Manuel Nagel
Thermosensation in the carpenter ant Camponotusrufipes
Authors: Manuel Nagel 1 , Christoph J. Kleineidam 1
Affiliation: 1 University of Konstanz, Department of Biology
Ants have a distinct sense of the environmental temperature, and they show this
amazing sensory ability by various fine-tuned thermo-guided behaviors, e.g. during
brood-care behavior. Interestingly, thermal preferences of individuals are not fixed
but depend on previous experience and time-of-day (circadian rhythmicity) as well as
on their own pupal temperature during development (Weidenmüller et al. (2009)
CurrBiol 19).
We are investigating the sensilla and associated thermo-sensitive neurons in the ants’
antenna to address the following questions: Which of the thermo-sensitive neurons
provide the necessary information for i) precise brood temperature assessment, ii)
detection of minute differences of temperature and iii) measurement of ambient
temperature over a wide range?
In this study, we identified two thermo-sensitive receptor neurons associated with
the sensillum coelocapitulum in the carpenter ant Camponotus rufipes.
One neuron function as a warm-receptor (activity increases with increasing
temperature) with a non-adapting tonic response and a working range of more than
10°C. This neuron continuously codes for mean environmental temperature,
comparable to a thermometer (TM-neuron).
The co-localized second neuron function as a cold-receptor (activity decreases with
increasing temperature) within a small temperature range that only covers the most
prevailing brood-temperature of 28-32°C. Within this temperature range, the neuron
is highly sensitive to differences in temperature. We propose that this neuron
179