Linked Life Data

8558598

Source:http://linkedlifedata.com/resource/pubmed/id/8558598

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1996-2-26
pubmed:abstractText
Using combined intracellular recordings and behavioral bioassays, it was found that lysozyme has two different effects in Paramecium, depending upon the concentrations used. At low concentrations (0.5 mM to 1.0 microM) it acts as an effective chemorepellent that causes reliable electrophysiological changes. Lysozyme-induced somatic depolarizations, isolated by blocking K+ channels with Cs-TEA, showed concentration dependencies that were well correlated with chemorepulsion. Ion dependency experiments showed that these were Ca++ based depolarizations. Addition of either Na+ or Mg++ improves chemorepulsion by providing additional depolarizations. Both the depolarizations and chemorepulsion were blocked by 10 microM neomycin, suggesting that the depolarization is necessary for this chemosensory transduction event. At higher concentrations (100 microM), lysozyme is a secretagogue. A transient inward current, recorded in Ca++ alone solutions with Cs-TEA present, was seen in response to high lysozyme concentrations. The amplitude of this inward current was well correlated with exocytosis. Addition of neomycin (1.0 mM) eliminated both the inward current and exocytosis, suggesting a causal relationship. Neither amiloride or W-7, compounds previously suggested to affect the electrophysiological responses to secretagogues, had any significant effects. The mucopolysaccharide hydrolysis activity of lysozyme was not required for any of these responses. We propose that Paramecium have a high affinity receptor on the body plasma membrane that responds to either lysozyme or a related compound to cause an increase in a novel body Ca++ conductance. This receptor-operated Ca++ conductance causes membrane depolarization and chemorepulsion at low concentrations and triggers a sufficient Ca++ influx at high concentrations to cause exocytosis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0022-2631
pubmed:author
pubmed:issnType
Print
pubmed:volume
148
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13-25
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Lysozyme acts as a chemorepellent and secretagogue in Paramecium by activating a novel receptor-operated Ca++ conductance.
pubmed:affiliation
Dept. of Biological Sciences, State Univ. of N.Y. at Buffalo 14260, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't