MULTICELLULAR-VESICLE-PROMOTING POLYPEPTIDE FROM TRICHOPLUSIA NI - TISSUE DISTRIBUTION AND N-TERMINAL SEQUENCE

An N-terminal amino acid sequence of a 16.9 kDa hemolymph polypeptide, ''Vesicle Promoting Factor'' (VPF) from Trichoplusia ni, revealed a h igh sequence homology (70%) with Manduca serta apolipophorin-III. A po lyclonal antibody developed against VPF, however, was not immunoreacti ve with either purified M. sexta or T. ni apolipophorin-III. Immunoblo ts of tissue homogenates of T. ni indicated that VPF was present in im aginal wing discs, central nervous system (CNS), silk glands, midgut a nd hemocytes from fifth instar larvae, and also in the IAL-TND1 cell l ine which can grow as either fluid-filled multicellular vesicles or mu lticellular aggregates. VPF was also detected immunologically in the h emolymph of adults of T. ni, and in hemolymph of adults and larvae of Galleria mellonella and Heliothis virescens. Testes, midgut, hemocytes , and wing discs, but not Malpighian tubules, of T. ni released VPF in to tissue culture medium during a 3 h incubation period. (C) 1995 Wile y-Liss, Inc.