Expression of actin in the central nervous system is switched off during diapause in the gypsy moth, Lymantria dispar

Diapause-regulated proteins were identified in the CNS of pharate 1st instar larvae of the gypsy moth, Lymantria dispar. Expression of two proteins (130 kDa and 45 kDa) declined at the time of diapause initiation and remained low during diapause. At diapause termination, following exposure to 5°C for at least 60 days, the 45-kDa protein was again highly expressed. Treatment of young pharate larvae with KK-42 averted diapause, and in such larvae, continued synthesis of the 45 kDa protein in the CNS was observed. These results suggest that expression of the 45-kDa protein is strongly down- regulated in the central nervous system (CNS) during diapause. Partial amino acid sequence determination suggested that the 45-kDa protein is actin, and this was confirmed using anti-actin antibodies. RT-PCR using primers designed from the sequence of the gypsy moth midgut actin-mRNA indicated that appearance of actin mRNA in the CNS followed the same patterns as that of the 45-kDa protein. The results indicate that diapause controls actin gene expression in the gypsy moth CNS and regulation is at the transcriptional level.