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The gut receptor of trypsin-modulating oostatic factor (TMOF), a decapeptide hormone that regulates trypsin biosynthesis in the mosquito gut, has been characterized. The binding of TMOF to mosquito gut membranes reached maximum at pH 7.4 and 24 degrees C. No binding was observed at pH 2.5 and the binding to the membranes declined rapidly at pH 8.0. At equilibrium, maximum binding to the receptor was observed at 60 min and 24 degrees C. A synthetic complementary decapeptide NH2-Ile-Leu-Gly-Arg-Gly-Gly-Gly-Gly-Gly-Gly-COOH (FOMT) for TMOF successfully competed with the gut receptor, and specifically bound TMOF (Kd = 4 microM and Kassoc = 2.5 x 10(5) M-1). TMOF binding to gut membranes was characterized with FOMT and a specific ELISA to the hormone at 24 and 72 h after blood feeding. Two classes of binding sites were found on the gut membrane; high affinity (Kd1 = 4.6 +/- 0.7 x 10(-7) M; Kassoc = 2.2 x 10(6) M-1 Bmax = 0.1 pmol/gut) and low affinity (Kd2 = 4.43 +/- 1 x 10(-6) M; Kassoc = 2.3 x 10(5) M-1; Bmax = 0.2 pmol/gut). The total binding sites for high and low affinity classes of TMOF per gut were estimated as 6.3 x 10(10) and 1.1 x 10(11) sites, respectively. Specific binding sites on the gut increased after the blood meal and were visualized by immunocytochemical staining. These results suggest that TMOF regulates trypsin biosynthesis by binding to specific receptor sites that are located on the mosquito gut, and that this receptor can be studied using a complementary peptide approach.

Samples of nine crystalline mustard oil glucosides including sinigrin were isolated from plant tissues of species in the families Cruciferae and Tropaeolaceae. The isolations were achieved by the use of column chromatography on neutral alumina, cellulose powder, activated carbon: by paper and thin-layer chromatography; and by crystallization from methanol-water mixtures.Feeding responses of fifth instar larvae of Plutella maculipennis (Curtis) were tested on agar-cellulose diets containing individual glucosides a t various concentrations in the presence or absence of 0.1 M glucose. The amount of feeding was measured by counts of frass pellets produced by the larvae during the test period. All the above-mentioned ~lucosides were found to act as feeding stimulants for the larvae of P. nzaculipennis. However, the relative palatability of these glucosides a t the same concentration (20 mg per 10 rnl of water in the diet) was found to be in the following order: progoitrin >glucocheirolin = glucoconringiin = glucoerucin >glucotropaeolin = sinigrin = sinalbin >gluconasturtiin = gluconapin. Higher concentrations of the glucosides, gluconasturtiin, and gluconapin were toxic to the larvae. Can. J. Zool. Downloaded from www.nrcresearchpress.com by Vancouver Island University on 11/21/14 For personal use only. SCIKLTZ, 0. E. and WAGNER, n'. 1956. Trennun~: dcr Senfolplrtcosidc durch absteigende Pnpierhromatngraphie. Z. Natrirforsch. 11B, 13-78. STEPANOJA, L. A. 1Ubl. The role of the foud factor in the mass rrpmduction of pests on Crucifcrae. EntomoI. Kev. USSR (English Trans.), 4R, 512-5 17. T A o n s~e t~~o~, A. J. 1953. The chernorartic responses that determine host specificity in an otigophagous insert (PIutdla na~culipcnnis Curt.). Can. J. Zool. 31, 51-72. VERSCHAEFFELT, E. 191n. The cause rletcrrniniril: the seleciion of lood in some herbivorous i n w t s . I'roc. Acad. Sci. (Aii~sterdnn~ ), 13, 536-542. YOGEL, 11;. G.. DOIZAKI, !I{. M., anrI Zrrrm, L. 1962. Rapid thin-layer chromatographic separation of phospholipids and neiltral lipid5 of serum. J. Lipirl Res. 3, 138-140. Y A M A M O~, R T. and FIUENKEL, G. 1960. -4ssay n l the principal guslatory stimulant for the tobacco hurnwol-nt, Pro!oparce sextcla (Johan.), from ~Ianaceons plants. Ann. EntomoI, %c. Am. 53, 499-503.Can. J. Zool. Downloaded from www.nrcresearchpress.com by Vancouver Island University on 11/21/14For personal use only.

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