ISSN:
1432-2048
Keywords:
Creep, in vivo
;
Growth equations
;
Phycomyces
;
Sporangiophore (Phycomyces)
;
Wall extensibility
;
Yield threshold
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The yielding properties of the cell wall, irreversible wall extensibility (m) and yield threshold (Y), are determined for stage I sporangiophores of Phycomyces blakesleeanus from in-vivo creep experiments, and compared to the values of m and Y previously determined for stage IVb sporangiophores using the same pressureprobe method (Ortega et al., 1989, Biophys. J. 56, 465). In either stage the sporangiophore enlarges (grows) predominately in length, in a specific region termed the “growing zone”, but the growth rates of stage I (5–20 urn · min−1) are smaller than those of stage IVb (30–70 μm · min−1). The results demonstrate that this difference in growth rate is the consequence of a smaller magnitude of m for stage I sporangiophores; the obtained values of P (turgor pressure), Y, and P-Y (effective turgor for irreversible wall extension) for stage I sporangiophores are slightly larger than those of stage IVb sporangiophores. Also, it is shown that the magnitude of m for the stage I sporangiophore is regulated by altering the length of the growing zone, Lg. A relationship between m and Lg is obtained which can account for the difference between values of m determined for stage I and stage IVb sporangiophores. Finally, it is shown that similar changes in the magnitude of m and ϕ (which have been used interchangeably in the literature as a measure of irreversible wall extensibility) may not always represent the same changes in the cell-wall properties.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00194284
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