NEB-COLLOOSTATIN, A 2ND FOLLICULOSTATIN OF THE GREY FLESHFLY, NEOBELLIERIA-BULLATA

During the purification of trypsin-modulating oostatic factor (TMOF) o f the grey fleshfly Neobellieria bullata, a new factor with oostatic a ctivity was discovered. We report herein its purification, primary str ucture and effects on oocyte development. Its amino acid sequence was determined as H-SIVPLGLPVPIGPIVVGPR-OH. Due to structural sequence sim ilarities with parts of several known collagens and its oostatic activ ity, we named it Neb-colloostatin. The synthetic peptide inhibits yolk uptake by previtellogenic oocytes and might have a role in the abscen ce of yolk deposition in penultimate oocytes. Neb-colloostatin does no t inhibit trypsin biosynthesis in the gut or ecdysone biosynthesis by larval ring glands. It decreases vitellogenin concentrations in the he molymph by an unknown mode of action. The role of ext acellular matrix proteins in the feedback control of growth is discussed.