Every ant reacts differently to social scents (pheromones). This interindividual variation in behavioural reaction is responsible for the emergent development of the division of work within an ant colony. Neuroethologist Dr. Christoph Kleineidam from the University of Konstanz is currently investigating the neuronal basis of interindividual variation. His research focuses mainly on ants and their highly sensitive sensory system that allows them to communicate with each other by way of pheromones. He believes that these sensory mechanisms can be technologically implemented in the fields of thermosensor and chemosensor technology in the not-too-distant future.
Pheromones are organic molecules used by members of the same species to communicate with each other on a biochemical level. Social insects that live in colonies with one or several queens, including ants and many bee and wasp species, have highly specific receptors and a highly sensitive sensory system with which they are able to perceive the tiniest amounts of a pheromone. Dr. Kleineidam's fascination for these remarkable sensory functions was what led him to become a neuroethologist. "During my studies, I investigated the sensory abilities of ants and discovered that the ants' antennas contained receptor cells that were able to measure the absolute carbon dioxide concentration in the air," said the biologist. At this point, he then decided to find out why ants possess such remarkable sensory capabilities. His current research, which focuses on different temperature receptors of ants and their function when orienting themselves in their thermal environment, soon led to the discovery of extremely sensitive receptor neurons that react quickly. "Sensory physiology opens up many more possibilities to explore the world of insects which would otherwise remain hidden," said Dr. Kleineidam explaining the background to his work.
Leafcutter ants, which are endemic to neotropical regions in South and Central America and parts of the southern United States, are a group of ant species with a highly developed social structure. It was for this reason that Dr. Christoph Kleineidam chose to use them for his research. "In contrast to ants in our part of the world such as southern wood ants (Formica rufa) which are omnivores, leafcutter ants live on fungi that they cultivate themselves," said Kleineidam. The ants collect leaf and plant parts, cut them into small pieces and use the substrate to cultivate the symbiotic fungus. Evolution led to worker ants with a remarkable variation in morphological traits, an adaptation that facilitates the division of labour. "As ants became more specialised, brain differences developed. I use such neuroanatomical differences, in particular those of the olfactory system, for my research in order to decipher the functional importance of these neuronal forms of organisation," said Christoph Kleineidam.
Leafcutter ants differ considerably in their olfactory systems despite the close relatedness of the workers, which have around 75 per cent of all genes in common. "There are three phenotypes that differ considerably in the organisation of the first olfactory neuropil. This means that the neuroanatomical difference leads to the phenotypes perceiving different scents for different purposes, for example a pheromone used to follow trails," said Dr. Kleineidam explaining this phenomenon.
Christoph Kleineidam's work focuses mainly on the identification of olfactory receptor genes, which starts with the isolation of RNA from the antennas (transcriptome analysis) of both worker- and sexual ants. The researchers then synthesise and sequence cDNA. The highly specific pheromone receptors are then identified in physiological experiments. Experiments carried out to investigate the ants' behaviour reveal their remarkable ability to perceive pheromones. "For example, we have been able to show that one milligramme of a specific pheromone would be sufficient to set up a trail that would encircle the earth 60 times. Such a high specificity is only possible with receptor genes that code for proteins that have a high ligand specificity," said Christoph Kleineidam explaining the process. This coding is necessary for the sensory system to work in a broad concentration range and make full use of signal amplification and adaptation.
After many years of research into the sensory systems of social insects, Dr. Christoph Kleineidam's major ambition is to work in cooperation with industry in the hope of being able to implement his findings in the technical field. "I believe that technical applications will soon be feasible in the field of thermosensor and chemosensor technology," said Dr. Kleineidam who is currently working on the identification of receptors in order to be able to investigate other adaptations of the cellular machinery that may have led to the high sensitivity observed. "In the long term, I think such sensor systems could be used in miniaturised biosensors. However, I do not have any concrete plans for this yet," said the neuroethologist.
Christoph Kleineidam currently holds a temporary professorship at the University of Konstanz where he benefits greatly from working with Prof. Galizia and his Department of Neurobiology with its unique infrastructure for measuring the neuronal activity of insects. "My expertise in the field of behavioural physiology and the socio-biology of social insects, as well as my great interest in the neuronal processing of scent information of insects, excellently complements the work of Dr. Galizia's team," said Dr. Kleineidam highlighting the positive synergies and the major advantages they bring to his research.
Dr. Christoph Kleineidam
Faculty of Biology
University of Konstanz
Tel.: +49 (0)7531/88-4407