title: Not flying blind: a comparative study of photoreceptor function in flying and non-flying cockroaches.
abstract: Flying is often associated with superior visual performance, as good vision is crucial for detection and implementation of rapid visually guided aerial movements. To understand the evolution of insect visual systems it is therefore important to compare phylogenetically related species with different investments in flight capability. Here, we describe and compare morphological and electrophysiological properties of photoreceptors from the habitually flying green cockroachPanchlora niveaand the American cockroachPeriplaneta americana, which flies only at high ambient temperatures. In contrast toPeriplaneta, ommatidia inPanchlorawere characterized by two-tiered rhabdom, which might facilitate detection of polarized light while flying in the dark. In patch-clamp experiments, we assessed the absolute sensitivity to light, elementary and macroscopic light-activated current and voltage responses, voltage-activated potassium (Kv) conductances, and information transfer. Both species are nocturnal, and their photoreceptors were similarly sensitive to light. However, a number of important differences were found, including the presence inPanchloraof a prominent transient Kvcurrent and a generally low variability in photoreceptor properties. The maximal information rate inPanchlorawas one-third higher than inPeriplaneta, owing to a substantially higher gain and membrane corner frequency. The differences in performance could not be completely explained by dissimilarities in the light-activated or Kvconductances; instead, we suggest that the superior performance ofPanchloraphotoreceptors mainly originates from better synchronization of elementary responses. These findings raise the issue of whether the evolutionary tuning of photoreceptor properties to visual demands proceeded differently in Blattodea than in Diptera.
authors.affiliation: Faculty of Science, Nano and Molecular Materials Research Unit, University of Oulu, PO Box 3000, Oulun Yliopisto 90014, Finland roman.frolov@oulu.fi.
authors.forename: Roman V
authors.identifier: 0000-0002-7431-5297
authors.initials: RV
authors.lastname: Frolov
authors.affiliation: Laboratory of Neuroethology, Sokendai (The Graduate University for Advanced Studies), Shonan Village, Hayama 240-0193, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Matsushita
authors.affiliation: Laboratory of Neuroethology, Sokendai (The Graduate University for Advanced Studies), Shonan Village, Hayama 240-0193, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Arikawa
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003058:Cockroaches / Q000033:anatomy & histology* / Q000502:physiology* / Q000648:ultrastructure; D054910:Compound Eye, Arthropod / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D005260:Female; D008297:Male; D046529:Microscopy, Electron, Transmission; D010526:Periplaneta / Q000033:anatomy & histology / Q000502:physiology / Q000648:ultrastructure; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure
keywords: Information processing; Panchlora nivea; Periplaneta americana; Visual ecology