Introduction Calliphora erythrocephala Munn and Greville, 1969 Wyatt and Pan, 1978 Riddiford and Law, 1983 Kanost et al., 1990 Telfer and Kunkle, 1991 Hyalophora cecropia Tojo et al., 1978 Tojo et al., 1978 1980 1985 Ryan et al., 1985 Bean and Silhacek, 1988 Jones et al., 1990 Jones et al., 1993 Memmel et al., 1994 Manduca sexta Kramer et al., 1980 Calliphora Telfer et al., 1983 Telfer and Massey, 1987 Miller and Silhacek, 1992 Magee et al., 1994 Pan and Telfer, 1999 Actias luna Pan and Telfer, 1996 H. cecropia Pan and Telfer, 1999 Hyalophora cecropia Danaus plexippus Ackery and Vane-Wright, 1984 Wheeler and Buck, 1996 Wheeler et al., 1999 Pan and Telfer, 1999 Materials and Methods 1. Experimental Insects Hyalophora cecropia Danaus plexippus Asclepias curasavica Asclepias syriaca 2. Antibodies H. cecropia Figure 1 Telfer et al., 1983 Telfer and Pan, 1988 Pan and Telfer, 1992 Figure 2, lane 1 Massey, 1995 Harlow and Lane, 1988 H. cecropia Figure 1 3. Tissue Preparation Pan and Telfer, 1990 The collected samples were stored frozen. For extraction, the tissue mixtures were thawed and transferred to a glass homogenizer. When chorionated eggs were present, they were crushed separately in a ceramic mortar and then combined with the rest of the tissues in the homogenizer. 4. Measurement of Antigen Concentrations Telfer et al., 1983 Telfer and Pan, 1988 Oudin, 1948 Pan and Telfer, 1990 1992 The measurements are of relative concentrations and are expressed as percentages of the concentration in a standard solution. For the hexamerins, extracts of abdomens from female pupae of each species were used as the standards; for VG, extracts of females containing chorionated eggs were used. The latter included newly eclosed adults in Cecropia and day 7 adults in long day Monarchs. 5. SDS-PAGE Electrophoresis Insoluble residues that would escape detection by immunodiffusion were monitored by SDS-PAGE. For this purpose 0.1 ml of each of the homogenized samples from a chosen stage were vortexed and pooled. The pooled sample was centrifuged in a microfuge (Beckman®) for 4 min. The lipid cap was removed, and the supernatant decanted. Pellet and supernatant were then separately dissolved in SDS-PAGE sample buffer so that equal volumes contained equal fractions of, respectively, the total pellet and supernatant material in the uncentrifuged pool. The samples were compared in neighboring lanes of pre-cast 4–15% gradient mini gels from Bio-Rad®. Electrophoresis was conducted at constant voltage (100 v), and terminated after 1 hr and 12 min. Coomassie Brilliant Blue staining was used to reveal the banding patterns. Results 1. Vitellogenin Figure 3 Telfer, 1954 Pan, 1971 Figure 3 Pan and Telfer, 1996 1999 Figure 3 Figure 4 Vg is stored as a solute in the hemolymph of female Cecropia pupae and accordingly centrifugal pellets of extracts at that stage did not produce detectable 180 and 40 kDa bands. In adults most Vg has been transferred to the yolk; pellets at this stage produced weak Vg bands due, presumably, to small yolk spheres that are not readily disrupted by homogenization. 2. Hexamerin utilization in females Cecropia Figure 5A Figure 4A, asterisks Figure 4A, lanes A1 and A2 Monarch Figure 6A Figure 6A Figure 4B, lanes Ast Figure 7 3. Sexual Differences. Figure 5B Figure 5A and B Figure 5B, Adult Figure 4A, stages A1 and A2, lanes P Figure 6B, green bars Figure 6A and B, red bars Figure 6A and B. blue bars Discussion 1. Egg formation versus metamorphosis Figure 6A Figure 7 Figure 6B Manduca sexta Kramer et al., 1980 Riddiford and Hice, 1985 Webb and Riddiford, 1988 Telfer et al., 1983 Blatta orientalis Duhamel and Kunkel, 1978 Pan and Telfer, 1996 Tojo et al., 1978 Riddiford and Hice, 1985 Jones et al, 1993 Memmel et al, 1994 Pan and Telfer, 1992 Figure 2 Pan and Telfer, 1996 Tojo et al, 1978 Tojo et al., 1978 2. How hexamerins support egg formation Wyatt, 1991 Paul and Kafatos, 1975 Nadel and Kafatos, 1980 Telfer and Pan, 1988 Hyphantria cunea Seo et al., 1998 Riptortus clavatus Chinzei et al., 1990 Miura et al., 1998 Bombyx mori Zhu et al., 1986 Chen and Yamashita, 1990 Riptortus Bombyx 3. Hexamerin synthesis in adults? Kunkel and Pan, 1976 Wyatt et al., 1992 4. V-MtH versus M-MtH Burmester et al., 1998