Silke Krüger, Casey S. Butler & Reinhard Lakes-Harlan (2011): Morphological and physiological regeneration in the auditory system of adult Mecopoda elongata (Orthoptera: Tettigoniidae). J. Comp. Physiol. A 197 (2), 181-192.
Abstract: Orthopterans are suitable model organisms for investigations of regeneration mechanisms in the auditory system. Regeneration has been described in the auditory systems of locusts (Caelifera) and of crickets (Ensifera). In this study, we comparatively investigate the neural regeneration in the auditory system in the bush cricket Mecopoda elongata. A crushing of the tympanal nerve in the foreleg of M. elongata results in a loss of auditory information transfer. Physiological recordings of the tympanal nerve suggest outgrowing fibers 5 days after crushing. An anatomical regeneration of the fibers within the central nervous system starts 10 days after crushing. The neuronal projection reaches the target area at day 20. Threshold values to low frequency airborne sound remain high after crushing, indicating a lower regeneration capability of this group of fibers. However, within the central target area the low frequency areas are also innervated. Recordings of auditory interneurons show that the regenerating fibers form new functional connections starting at day 20 after crushing. URL: http://www.springerlink.com/content/w721215082h77g03/ For reprints please contact Reinhard Lakes-Harlan (email: [email protected]) Doreen Möckel, Ernst-August Seyfarth & Manfred Kössl (2011): Otoacoustic emissions in bushcricket ears: general characteristics and the influence of the neuroactive insecticide pymetrozine. J. Comp. Physiol. A 197 (2), 193-202. Abstract: The tympanal organ of the bushcricket Mecopoda elongata emits pronounced distortion-product otoacoustic emissions (DPOAEs). Their characteristics are comparable to those measured in other insects, such as locusts and moths, with the 2f1–f2 emission being the most prominent one. Yet the site of their generation is still unclear. The spatial separation between the sound receiving spiracle and the hearing organ in this species allows manipulations of the sensory cells without interfering with the acoustical measurements. We tried to interfere with the DPOAE generation by pharmacologically influencing the tympanal organ using the insecticide pymetrozine. The compound appears to act selectively on scolopidia, i.e., the mechanosensor type characteristically constituting tympanal organs. Pymetrozine solutions were applied as closely as possible to the scolopidia via a cuticle opening in the tibia, distally to the organ. Applications of pymetrozine at concentrations between 10−3 and 10−7 M to the tympanal organ led to a pronounced and irreversible decrease of the DPOAE amplitudes. URL: http://www.springerlink.com/content/a173m40732850121/ For reprints please contact D. Möckel (email: [email protected]) Kind regards Sonja ************************** Dr. Sonja Amoser Steinrieglstraße 286 3400 Weidlingbach [email protected]
