Formation of multiplex lamellae by equilibrium slow freezing of cortical parenchyma cells of mulberry and its possible relationship to freezing tolerance

PROTOPLASMA ◽  
1996 ◽  
Vol 190 (3-4) ◽  
pp. 189-203 ◽  
Author(s):  
S. Fujikawa ◽  
K. Takabe
Keyword(s):  
Freezing Tolerance ◽  
Slow Freezing ◽  
Cortical Parenchyma ◽  
Parenchyma Cells

Effect of cycloheximide on the freezing tolerance and ultrastructure of cortical parenchyma cells from mulberry twigs

1983 ◽  
Vol 61 (8) ◽  
pp. 2205-2211 ◽  
Author(s):  
T. Niki ◽  
A. Sakai
Keyword(s):  
Freezing Tolerance ◽  
Ultrastructural Changes ◽  
Cortical Cells ◽  
Cytological Change ◽  
Cortical Parenchyma ◽  
Parenchyma Cells ◽  
Cytological Changes ◽  
The Relationship ◽  
Further Development ◽  
In Cells

Experiments were performed using cycloheximide (CHI) on cortical parenchyma cells from mulberry twigs (Morus bombyciz cv. Gorogi) to understand the relationship between the sequence of cytological changes suggesting replacement of the plasmamembrane and the rapid increase in freezing tolerance. Cortical cells from twigs collected on October 16 and 27, which were hardy to −10 and −15 °C, respectively, were still alive after cooling to −70 °C if they had been exposed to −3 °C for 10 to 12 days. In these hardened cells, appearance of microvesicles (MVs) in the peripheral cytoplasm and fusion of these MVs with plasmamembrane were characteristically observed. Neither cytological change nor increase of freezing tolerance was observed in cells treated by CHI before their exposure to −3 °C for 10 to 12 days. However, the suppression of such changes by CHI treatment was effective only in cells which were hardy at −10 to −15 °C and not in the cells of twigs collected on November 4, which were hardy to −20 °C. Consequently, synthesis of some functional proteins during hardening was required for the further development of freezing tolerance, and synthesis had been accomplished before the cells became hardy to −20 °C. Ultrastructural changes brought about by CHI treatment suggest that synthesis of some functional proteins related to the presumed changes of plasmamembrane occurs during hardening.

Early modifications of the internodal anatomy of Glycine max sprayed with 2,4-DB

1979 ◽  
Vol 57 (12) ◽  
pp. 1340-1344 ◽  
Author(s):  
Thompson Demetrio Pizzolato ◽  
David L. Regehr
Keyword(s):  
Cell Division ◽  
Cell Enlargement ◽  
Secondary Phloem ◽  
Anatomical Changes ◽  
Phloem Parenchyma ◽  
Cortical Parenchyma ◽  
Parenchyma Cells ◽  
Radial Cell ◽  
Orderly Fashion ◽  
Stimulation Of

An aqueous spray of 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) induces anatomical changes in young Glycine internodes. Four days after spraying, the first symptoms appear outside the cambium when the interfascicular parenchyma cells and the adjacent cortical parenchyma cells enlarge and divide in several planes. Four days later, the metaphloem parenchyma cells in many of the leaf traces undergo considerable periclinal cell division and extensive radial cell enlargement. The phloem parenchyma cells of the late metaphloem and first secondary phloem enlarge and divide in a less orderly fashion. Fifteen days after treatment, the cortical parenchyma is modified into a band of radially seriate cells above the protophloem fibers. Products of this cambium-like region convert the cortex into a callus-like tissue. The size of starch grains is reduced initially in the phloem and xylem and later in the cortex. It appears that the stimuli produced by 2,4-DB move into the internode via the metaphloem of leaf traces. Despite the rapid obliteration of conducting phloem by the 2,4-DB induced stimulation of phloem parenchyma, an accelerated differentiation of secondary phloem compensates for this loss.

Fracture Properties of an Anisotropic Biological Cellular Material - Apple Flesh

1990 ◽  
Vol 207 ◽  
Author(s):  
Ali A. Khan ◽  
Julian F. V. Vincent
Keyword(s):  
Fracture Toughness ◽  
Marked Effect ◽  
Crack Opening ◽  
Cellular Material ◽  
Taste Panel ◽  
Slow Freezing ◽  
Intercellular Spaces ◽  
Fracture Properties ◽  
Parenchyma Cells ◽  
Fracture Tests

AbstractThe texture of apple flesh is important in assessing its eating qualities. The texture in turn is related to the structure of the parenchyma. The parenchyma cells of the fruit are arranged in radial quasi-columnar form with radial spaces in between. This anisotropy has a marked effect on the fracture properties such that it is much easier to drive a crack between the columns (radially) than to drive it across them (tangentially). The fracture tests used were simple crack-opening tests under tension or using a wedge. This difference was also detected by a taste panel. The radial spaces ease the passage of cracks travelling along them, and act as crack stoppers for cracks travelling at right angles to them. They also allow the cells to deform more in one orientation more giving the structure ductility and making the apple tougher in that orientation. It is possible to increase this effect by controlled damage such as slow freezing which causes the intercellular spaces to expand increasing the crack-stopping mechanisms and increasing the ductility, therefore increasing the fracture toughness. Toughness first increases, then decreases with increasing damage. This effect can be mimicked with brittle paper: fracture toughness of tracing paper initially increases if holes are punched randomly in it.

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