spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online August 14, 2009
Journal of Experimental Biology 212, 2767-2772 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.031278
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Google Scholar
Right arrow Articles by Toyoda, T.
Right arrow Articles by Nakaoka, Y.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Toyoda, T.
Right arrow Articles by Nakaoka, Y.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

Thermo-sensitive response based on the membrane fluidity adaptation in Paramecium multimicronucleatum

Taichi Toyoda1, Yoshinori Hiramatsu2, Toshiaki Sasaki1 and Yasuo Nakaoka1,2,*

1 Biophysical Dynamics Laboratories, Graduate School of Frontier Bioscience, Osaka University, Toyonaka, Osaka 560-8531, Japan
2 Division of Biophysical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan

* Author for correspondence (nakaoka{at}bpe.es.osaka-u.ac.jp)

Accepted 9 June 2009

Relationships between the thermo-sensitive response and membrane lipid fluidity were studied using a ciliated protozoan, Paramecium multimicronucleatum. Paramecium elicits a transient membrane depolarization in response to a cooling stimulus (temperature drop). The depolarization amplitude was largest when the cooling stimulus was started from the culture temperature, whilst when cooling started at a temperature more than 5°C higher or lower than the culture temperature, only a small depolarization was induced. Therefore, the cooling-induced response was dependent on the culture temperature and its sensitivity to the cooling stimulus was highest at the culture temperature. Membrane fluidity measurements of living cells using the fluorescent dye 6-lauroyl-2-dimethylaminonaphthalene (laurdan) showed that the fluidity measured at the culture temperature was almost constant irrespective of the temperature at which the cells had been cultured and adapted, which is consistent with homeoviscous adaptation. The constant fluidity at the culture temperature quickly decreased within a few seconds of application of the cooling stimulus, and the decreased fluidity gradually readapted to a constant level at the decreased temperature within 1 h. When the constant fluidity at culture temperature was modified by the addition of procaine or benzyl alcohol, the cooling-induced depolarization was completely abolished. These results suggest the possibility that the adaptation of fluidity to a constant level and its quick decrease below the constant level activate cooling-sensitive channels to elicit the transient depolarization.

Key words: temperature, adaptation, cooling-induced response, membrane fluidity, laurdan fluorescence, Paramecium


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?




© The Company of Biologists Ltd 2009