Biological activity of structural analogs and effect of oil as a carrier of trypsin modulating oostatic factor of the gray fleshfly Neobellieria bullata.
ABSTRACT The trypsin modulating oostatic factor from the gray fleshfly Neobellieria bullata (Neb-TMOF) is released from the ovary at the end of vitellogenesis and inhibits trypsin biosynthesis in the midgut. This inhibition indirectly results in an arrest of oocyte growth. Additional experiments with N. bullata were performed to characterize its trypsin modulating and oostatic properties in more detail. After suspending the peptide in wheat germ oil, the threshold dose for oostatic activity was lowered one thousand times (2.10(-5) in oil versus 2.10(-2) pmoles per fly in Ringer). By use of the Neobellieria trypsin biosynthesis assay, 17 analogs of the hexapeptide were tested for inhibitory activity. The following structural elements were demonstrated to be critical for biological activity: the alcohol function at position 3 (Thr residue); a positively charged basic group at the C terminus (His residue); and the Asn side chain at positions 1 and 4.
Article: Oostatic peptides.[Show abstract] [Hide abstract]
ABSTRACT: Oostatic peptides are organic molecules, which influence an insect reproduction due to a regulation of the eggs development. It was proved that decapeptide-H-Tyr-Asp-Pro-Ala-Pro-Pro-Pro-Pro-Pro-Pro-OH (YDPAPPPPPP)-isolated from mosquito Aedes aegypti, inhibits trypsin activity in the midgut of the mosquito. Therefore, it was named trypsin-modulating oostatic factor (Aea-TMOF). Feeding the recombinant cells with cloned and expressed TMOF on the coat protein of tobacco mosaic virus (TMV) to mosquito larvae, caused larval mortality. The TMOF was therefore designed for usage as a new biorational insecticide against mosquito. Similarly, a hexapeptide-H-Asn-Pro-Thr-Asn-Leu-His-OH (NPTNLH)-was isolated from the grey flesh fly Neobellieria bullata. This peptide and some of its analogs inhibited trypsin-like synthesis by the midgut in female flies and was therefore entitled Neb-TMOF. Interestingly, the synthetic Aea-TMOF and mainly its C-terminus shorten analogs, including those containing D-amino acids or methylene-oxy isosteric bond, quickly and strongly inhibited the hatchability and egg development in the flesh fly N. bullata.Amino Acids 01/2013; 44(4). DOI:10.1007/s00726-012-1449-x · 3.65 Impact Factor
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ABSTRACT: Companies dealing with a large customer base and especially those with infrequent purchase or service interactions face the challenge of developing and maintaining a long-term relationship with customers. In addition to offering products for sale, marketing communications can add significantly to the customer relationship and brand-building process. Traditionally, customer contact is maintained using a campaign-oriented, effort-by-effort approach to selecting customers for contact. This paper suggests development of a Longitudinal Contact Strategy™ to plan customer contacts over a substantial time horizon. Data analysis can be used to determine (a) what to say to the customer, (b) when to make the contact, and (c) how much to spend on each customer. Results can be measured by comparing the cumulative marketing expense to the cumulative revenue produced. © 1998 John Wiley & Sons, Inc. and Direct Marketing Educational Foundation, Inc.Journal of Interactive Marketing 01/1998; 12(1):56 - 62. DOI:10.1002/(SICI)1520-6653(199824)12:1<56::AID-DIR7>3.0.CO;2-7 · 1.68 Impact Factor