Ultrastructure and physiology of the CO₂ sensitive sensillum ampullaceum in the leaf-cutting ant Atta sexdens

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• 作者：Kleineidam ; Christoph ; Romani ; Roberto ; Tautz ; Jü ; rgen ; Isidoro ; Nunzio
• 关键词：Carbon dioxide ; Insects ; Microclimate ; Non-adapting ; Sensory organ
• 刊名：Arthropod Structure and Development
• 出版年：2000
• 出版时间：January, 2000
• 年：2000
• 卷：29
• 期：1
• 页码：43-55
• 全文大小：2.90 M

文摘

The sensilla ampullacea on the apical antennomere of the leaf-cutting ant Atta sexdens were investigated regarding both their responses to CO₂ and their ultrastructure. By staining the sensillum during recording, we confirmed that the sensilla ampullacea are responsible for CO₂ perception. We showed that the sensory neurons of the sensilla ampullacea are continuously active without adaptation during stimulation with CO₂ (test duration: 1 h). This feature should enable ants to assess the absolute CO₂ concentration inside their nests. Sensilla ampullacea have been found grouped mainly on the dorso-lateral side of the distal antennal segment. Scanning and transmission electron microscopic investigations revealed that the external pore opens into a chamber which connects to the ampulla via a cuticular duct. We propose protection against evaporation as a possible function of the duct. The ampulla houses a peg which is almost as long as the ampulla and shows cuticular ridges on the external wall. The ridges are separated by furrows with cuticular pores. The peg is innervated by only one sensory neuron with a large soma. Its outer dendritic segment is enveloped by a dendritic sheath up to the middle of the peg. From the middle to the tip numerous dendritic branches (up to 100) completely fill the distal half of the peg. This is the first report of a receptor cell with highly branched dendrites and which probably is tuned to CO₂ exclusively.