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Extension growth of the water mold Achlya: interplay of turgor and wall strength.
MedLine Citation:
PMID:  11607292     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
When hyphae of the water mold Achlya were subjected to osmotic stress, imposed with polyethylene glycol (PEG)-300 or sucrose, turgor pressure fell in proportion to the increase in external osmotic pressure. There was no evidence of turgor regulation, even over a period of days, yet the extension rate was unaffected until turgor was reduced to less than a third of the normal level of 0.6-0.8 MPa (6-8 bars). Measurements of the pressure at which the hyphae burst indicate that they respond to osmotic stress by softening their apical cell walls, sustaining extension growth despite reduced turgor pressure. The effect of osmolytes excluded by the wall was very different; superfusion of growing hyphae with PEG-6000 or dextran-6000 reduced turgor and stopped extension but did not induce wall softening. Furthermore, the hyphae did not resume growth during an hour or more of continuous exposure to these substances. Although the two classes of osmolytes have the same effect on turgor, they may induce different strains within the cell wall; this might then affect the capacity of the organism to detect the drop in turgor or to soften its cell wall. The interplay between turgor and wall strength supports the proposition that turgor supplies the driving force for extension and that production of the standard hyphal form requires a balance between hydrostatic pressure and a resistive cell wall.
Authors:
N P Money; F M Harold
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  89     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1992 May 
Date Detail:
Created Date:  2001-10-18     Completed Date:  2001-12-07     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4245-9     Citation Subset:  -    
Affiliation:
Department of Biochemistry, Colorado State University, Fort Collins, CO 80523, USA.
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