Document Detail

Schistosoma mansoni: eggshell formation is regulated by pH and calcium.
MedLine Citation:
PMID:  1915744     Owner:  NLM     Status:  MEDLINE    
The protein precursors of the schistosome eggshell are synthesized and packaged into secretory vesicles in the vitelline cells. These vesicles appear to contain an emulsion of eggshell precursor material. Evidence is presented to show that these secretory vesicles are acidic as in other systems and that this acidity stabilizes the emulsion and prevents the eggshell cross-linking reactions from occurring. Alkalinizing treatments trigger eggshell formation within the secretory vesicles as shown by (1) the induction of autofluorescence and (2) by electron microscopy which shows that the eggshell precursors have aggregated within the secretory vesicles into spherical particles bearing microspines. These aggregates formed in the secretory vesicles were isolated and shown to have the same protease resistance and amino acid composition as authentic eggshell. The calcium ionophore A23187 induces scattered autofluorescence in intact female worms which electron micrographs show to be due to exocytosis of eggshell material. Based on these observations we propose a model for the formation of schistosome eggshell and suggest that it may apply to all trematodes in which the eggshell precursors are present as stable emulsions in the secretory vesicles of the vitelline cells.
K E Wells; J S Cordingley
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Experimental parasitology     Volume:  73     ISSN:  0014-4894     ISO Abbreviation:  Exp. Parasitol.     Publication Date:  1991 Oct 
Date Detail:
Created Date:  1991-11-07     Completed Date:  1991-11-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370713     Medline TA:  Exp Parasitol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  295-310     Citation Subset:  IM    
Department of Molecular Biology, University of Wyoming, Laramie 82071.
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MeSH Terms
Ammonium Chloride / pharmacology
Calcimycin / pharmacology
Calcium / physiology*
Cytoplasmic Granules / ultrastructure
Egg Proteins / metabolism*
Helminth Proteins / metabolism*
Hydrogen-Ion Concentration
Microscopy, Electron
Microscopy, Fluorescence
Monensin / pharmacology
Monophenol Monooxygenase / metabolism
Ovum / physiology*,  ultrastructure
Protein Precursors / metabolism*
Schistosoma mansoni / physiology*,  ultrastructure
Reg. No./Substance:
0/Egg Proteins; 0/Helminth Proteins; 0/Protein Precursors; 12125-02-9/Ammonium Chloride; 17090-79-8/Monensin; 52665-69-7/Calcimycin; 7440-70-2/Calcium; EC Monooxygenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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