Linked Life Data

7657713

Source:http://linkedlifedata.com/resource/pubmed/id/7657713

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1995-10-2
pubmed:abstractText
The plasma membrane of ciliates is underlaid by a vast continuous array of membrane vesicles known as cortical alveoli. Previous work had shown that a purified fraction of these vesicles actively pumps calcium, suggesting that alveoli may constitute a calcium-storage compartment. Here we provide direct confirmation of this hypothesis using in situ visualization of total cell calcium on sections of cryofixed and cryosubstituted cells analyzed by SIMS (secondary ion mass spectrometry) microscopy a method never previously applied to protists. A narrow, continuous, Ca-emitting zone located all along the cell periphery was observed on sections including the cortex. In contrast, Na and K were evenly distributed throughout the cell. Various controls confirmed that emission was from the alveoli, in particular, the emitting zone was still seen in mutants totally lacking trichocysts, the large exocytotic organelles docked at the cell surface, indicating that they make no major direct contribution to the emission. Calcium concentration within alveoli was quantified for the first time in SIMS microscopy using an external reference and was found to be in the range of 3 to 5 mM, a value similar to that for sarcoplasmic reticulum. After massive induction of trichocyst discharge, this concentration was found to decrease by about 50%, suggesting that the alveoli are the main source of the calcium involved in exocytosis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9533
pubmed:author
pubmed:issnType
Print
pubmed:volume
108 ( Pt 5)
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1895-909
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Direct visualization of a vast cortical calcium compartment in Paramecium by secondary ion mass spectrometry (SIMS) microscopy: possible involvement in exocytosis.
pubmed:affiliation
Laboratoire de Biologie Cellulaire 4 (CNRS, URA 1134), Bâtiment 444, Université Paris-Sud, Orsay, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't