title: Autofluorescence lifetime variation in the cuticle of the bedbug Cimex lectularius.
abstract: The decay time of the fluorescence of excited molecules, called fluorescence lifetime, can provide information about the cuticle composition additionally to widely used spectral characteristics. We compared autofluorescence lifetimes of different cuticle regions in the copulatory organ of females of the bedbug, Cimex lectularius. After two-photon excitation at 720 nm, regions recently characterised as being rich in resilin showed a longer bimodal distribution of the mean autofluorescence lifetime τm(tau-m) at 0.4 ns and 1.0-1.5 ns, while resilin-poor sites exhibited a unimodal pattern with a peak around 0.8 ns. The mean lifetime, and particularly its second component, can be useful to distinguish resilin-rich from resilin-poor parts of the cuticle. The few existing literature data suggest that chitin is unlikely responsible for the main autofluorescent component observed in the resilin-poor areas in our study and that melanin requires further scrutiny. Autofluorescence lifetime measurements can help to characterise properties of the arthropod cuticle, especially when coupled with multiphoton excitation to allow for deeper tissue penetration.
authors.affiliation: Applied Zoology, Department of Biology, Technische Universität Dresden, 01062 Dresden, Germany. Electronic address: klaus.reinhardt@tu-dresden.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Reinhardt
authors.affiliation: JenLab GmbH, Schillerstr. 1, 07745 Jena, and Science Park 2, Campus D1.2, 66123 Saarbrücken, Germany.
authors.forename: Hans Georg
authors.initials: HG
authors.lastname: Breunig
authors.affiliation: JenLab GmbH, Schillerstr. 1, 07745 Jena, and Science Park 2, Campus D1.2, 66123 Saarbrücken, Germany; Saarland University, Department of Biophotonics and Laser Technology, Campus A5.1, 66123 Saarbrücken, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: König
mesh_terms: D000818:Animals; D001511:Bedbugs; D002686:Chitin / Q000737:chemistry*; D005260:Female; D005453:Fluorescence; D021621:Imaging, Three-Dimensional; D019476:Insect Proteins / Q000737:chemistry*; D008027:Light; D008543:Melanins / Q000737:chemistry; D036641:Microscopy, Fluorescence, Multiphoton; D017785:Photons; D012098:Reproduction; D012726:Sexual Behavior, Animal
chemical_list: D019476:Insect Proteins; D008543:Melanins; C047663:cuticle proteins, insects; D002686:Chitin; C030951:resilin
keywords: 4D imaging; Arthropod cuticle; Chitin; FLIM; Fluorescence decay; Melanin; Two-photon excited autofluorescence (TPEF)