Crickets in space

"Crickets in Space" (CRISP) was a Neurolab experiment by which the balance between genetic programs and the gravitational environment for the developm ent of a gravity sensitive neuronal system was studied. The model character of crickets was justified by their external gravity receptors, identified position-sensitive interneurons (PSI) and gravity-related compensatory head response, and by the specific relation of this behavior to neuronal activa tion systems. These advantages allowed us to study the impact of modified g ravity on cellular processes in a complex organism. Eggs, l(st), 4(th) and 6(th) stage larvae of Acheta domesticus were used. Post-flight experiments revealed a low susceptibility of the behavior to microgravity (mug) and hyp ergravity (hg) while the physiology of the PSI was significantly affected. Immunocytological investigations revealed a stage-dependent sensitivity of thoracic GABAergic motoneurons to 3g-conditions concerning their soma sizes but not their topographical arrangement. Peptidergic neurons from cerebral sensorimotor centers revealed no significant modifications by microgravity . The contrary physiological and behavioral results indicate a facilitation of Ig-readaptation by accessory gravity, proprioceptive and visual sense o rgans. Absence of anatomical modifications point to an effective time windo w of mug- or hg-exposure related to the period of neuronal proliferation. ( C) 2001 Elsevier Science Ltd. All rights reserved.