Cercal sensory system and giant interneurons in Gryllodes sigillatus.
The external morphologies of two cricket species, Gryllodes sigillatus and Gryllus bimaculatus, were investigated. Despite its small body length, G. sigillatus possessed longer cerci and longer cercal filiform hairs than G. bimaculatus. The estimated number of filiform hairs on a cercus was also larger in G. sigillatus than in G. bimaculatus. Wind-sensitive interneurons receiving sensory inputs from cercal filiform hairs and running in the ventral nerve cord (VNC) were investigated in G. sigillatus both morphologically and physiologically. By intracellular staining, these interneurons were proved to be morphologically homologous with previously identified giant interneurons (GIs 8-1, 9-1, 9-2, 9-3, 10-2, and 10-3) in G. bimaculatus and Acheta domesticus. In G. sigillatus, the intensity-response relationship (I-R curve) for each GI was investigated using a unidirectional air current stimulus. The stimulus was applied from 12 different directions, and an I-R curve was obtained for each stimulus direction. Each GI showed a characteristic I-R curve depending on stimulus direction. The directionality curve expressed in terms of threshold velocity showed that each GI had a distinctive directional characteristic. The functional properties of GIs in G. sigillatus, such as I-R curve, threshold velocity, and directional characteristics, were compared with those of homologous GIs in G. bimaculatus in Discussion.
Kanou
Masamichi
M
Department of Biology, Faculty of Science, Ehime University, Matsuyama, Japan. kanou@mserv.sci.ehime-u.ac.jp
Nawae
Miyuki
M
Kuroishi
Hiroyuki
H
D000392:Air Movements; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D049628:Body Size / Q000502:physiology; D004924:Escape Reaction / Q000502:physiology; D005260:Female; D006135:Gryllidae / Q000033:anatomy & histology / Q000502:physiology*; D007395:Interneurons / Q000502:physiology*; D008297:Male; D012677:Sensation / Q000502:physiology*