European journal of entomology vol:92 issue:1 pages:143-149
Trypsin Modulating Oostatic Factor (TMOF) of the grey fleshfly Neobellieria bullata is a hexapeptide that has been isolated from vitellogenic ovaries. Its precursor is a 75 kDa protein that is abundantly present in oocytes but absent from hemolymph. TMOF inhibits trypsin biosynthesis in the gut, it lowers yolk polypeptide concentration in the hemolymph and strongly inhibits ecdysone biosynthesis by larval ring glands. Evidence is presented that a molecule with identical chromatographic behaviour and physiological effects is also present in the larvae of Neobellieria at the time when they stop feeding, Ecdysone inhibition does not suppress trypsin modulating activity of the hexapeptide. This, in combination with results that were obtained with four slightly different TMOF analogs, suggests that the inhibitory activity of trypsin biosynthesis is independent from that of ecdysone regulation. Several compounds that were tested for initiation or increase in trypsin biosynthesis in the gut were not active.