ACTIVITY OF INSULIN GROWTH-FACTORS AND SHRIMP NEUROSECRETORY ORGAN EXTRACTS ON A LEPDOPTERAN CELL-LINE

Ecdysteroids, or molting hormones, have been proven to be key differen tiation regulators for epidermal cells in the postembryonic developmen t of arthropods. Regulators of cell proliferation, however, remain lar gely unknown. To date, no diffusible insect peptidic growth factors ha ve been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vi tro tests for the preliminary characterization of potential growth fac tors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-PID2) established f rom imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-PID2 cells. We tested mammalian insulin and insulin-like growth factors (ICF-I, ICF-II). Fo llowing an arrest of cell proliferation by serum deprivation, IGF-I an d ICF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested t he proliferation of the IAL-PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors or iginating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural cha in compensated for serum deprivation and stimulated completion of mito sis. (C) 1997 Wiley-Liss, Inc.