Document Detail

Yolk granules are differentially acidified during embryo development in the stick insect Carausius morosus.
MedLine Citation:
PMID:  11572096     Owner:  NLM     Status:  MEDLINE    
Newly laid eggs of stick insects comprise a unique fluid ooplasm that is gradually partitioned into a number of yolk granules by invasion of secondary vitellophages. This study aimed at establishing how yolk granules become acidified in the course of embryonic development. Data show that acidified yolk granules are rather scarce and randomly distributed in vitellophages of early embryos, while they tend to increase gradually in number as development proceeds to completion. Yolk granule acidification is progressively more inhibited in the presence of increasing concentrations of chloroquine, monensin and bafilomycin. A pro-protease was identified cytochemically and by immunoblotting in yolk extracts of progressively more advanced embryos. A specific monoclonal antibody raised against this pro-protease helped to demonstrate that it is gradually processed to yield a lower molecular weight polypeptide as development proceeds to completion. This latter polypeptide was identified as a protease using electrophoresis in polyacrylamide gels containing yolk extracts. Simultaneous administration of a fluorescent substrate for cysteine protease and an acidotropic probe produced superimposable labelling patterns, suggesting that only acidified yolk granules possess a proteolytic activity. On the other hand, yolk granules probed simultaneously for acidification and latent pro-protease yielded labelling patterns partially superimposed. Pro-protease labelling is gradually lost as yolk granules are progressively more acidified during development. Distinct labelling patterns were also obtained in vitellophages processed for the simultaneous detection of pro-protease and protease, suggesting that the two activities are expressed by different yolk granule populations, and that one is gradually converted into the other as time goes by.
A M Fausto; G Gambellini; M Mazzini; A Cecchettini; M Masetti; F Giorgi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Cell and tissue research     Volume:  305     ISSN:  0302-766X     ISO Abbreviation:  Cell Tissue Res.     Publication Date:  2001 Sep 
Date Detail:
Created Date:  2001-09-26     Completed Date:  2002-02-19     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0417625     Medline TA:  Cell Tissue Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  433-43     Citation Subset:  IM    
Department of Environmental Sciences, Tuscia University, Viterbo, Italy.
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MeSH Terms
Acids / metabolism*
Cytoplasmic Granules / enzymology,  ultrastructure
Egg Proteins / metabolism*
Egg Yolk / enzymology*,  ultrastructure
Embryo, Nonmammalian / metabolism
Endopeptidases / metabolism*
Reg. No./Substance:
0/Acids; 0/Egg Proteins; EC 3.4.-/Endopeptidases

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