אסיף מאגר המחקר החקלאי

Termination of vitellogenesis in follicles of the moth, Plodia interpunctella: Changes in oocyte and follicular epithelial cell activities

Year:

1995

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Volume :

29

Co-Authors:

Zimowska, G., Insect Attractants, Behavior, and Basic Biology Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, United States, Department of Invertebrate Physiology, University of Warsaw, Warszawa, Poland
Shirk, P.D., Insect Attractants, Behavior, and Basic Biology Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, United States
Silhacek, D.L., Insect Attractants, Behavior, and Basic Biology Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, United States
Shaaya, E., Volcani Center, Agricultural Research Organization, Bet-Dagan, Israel

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Abstract:

The production and uptake of the follicular epithelium yolk protein (FEYP) is terminated coincident with the initiation of vitelline membrane synthesis in follicles of the Indianmeal moth, Plodia interpunctella (Hübner). This was determined by visualizing the cytolocalization of the FEYP subunits YP2 and YP4 using antisera to immunolabel ultrathin sections or whole‐mounted ovaries. Both subunits of FEYP were detectable in the Golgi apparatus and associated secretory granules of the follicular epithelial cells (FC) in vitellogenic follicles. Before the follicles entered the terminal growth phase, the oocytes began production of specialized organelles, late yolk spheres. Following the appearance of late yolk spheres in the oocyte, the FC initiated the production of vitelline membrane proteins and the rapid clearance of YP2 from their cytoplasm. No YP2 was detected in the Golgi apparatus or in the secretory granules of FC from follicles in terminal growth phase, although YP4 was detected in these organelles. The vitelline membrane of follicles in termal growth phase was a bilayered structure with an electron‐dense layer of vitelline membrane proteins that originated in the FC and an electron‐translucent layer containing yolk proteins. During this period, late yolk spheres were observed fused with the oolemma exposing and possibly releasing their contents to the electron‐translucent layer of the vitelline membrane. From this evidence, we suggest that during termination of vitellogenesis, the oocyte and FC work in concert to end uptake of yolk proteins and begin the synthesis of egg membranes, and that the oocyte contributes to the production of vitelline membrane by the release of previously sequestered yolk proteins. © 1995 Wiley‐Liss, Inc. Copyright © 1995 Wiley‐Liss, Inc.

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