SUBOPTIMAL TEMPERATURE-DEPENDENT CHANGES IN THE BRAIN-DEVELOPMENT ANDACTIVITY IN GALLERIA-MELLONELLA LARVAE

The development of Galleria mellonella larvae is strongly affected by suboptimal temperature (18 degrees C). One-day-old last-instar larvae react to 18 degrees C with the arrest of further development for sever al months described as facultative larval diapause, The aim of this st udy was to find what type of changes, if any, in the brain correlate w ith the larval diapause induced by suboptimal temperature, Morphologic al analysis demonstrated the gradual inhibition of brain development. Paraldehyde-fuchsin (PAF) staining revealed cyclicity in the activity of the medial neurosecretory cells (M-NSC) in the larval brain, SDS-PA GE was used to examine the brain proteins of larvae reared at 30 degre es C and at 18 degrees C. The rate of protein synthesis in the brain o f the last instar larvae kept at 18 degrees C, measured as L-[S-35]met hionine incorporation during 2-h incubation in vitro, was only about 4 0% of the value characteristic for this tissue during normal developme nt (at 30 degrees C), Despite decrease in the rate of total protein sy nthesis, suboptimal temperature induced an increase in the level of tw o major brain proteins: 112 and 84 kDa, In SDS-PAGE analysis, these tw o proteins appear 21-28 days after transfer to the lower temperature. Whether these proteins are specific for induction of larval diapause o f Galleria mellonella remains to be further investigated. (C) 1998 Wil ey Liss, Inc.