The effect of pH and ABA on the hydraulic conductivity of Nitella membranes

1977 ◽  
Vol 55 (1) ◽  
pp. 1-4 ◽  
Author(s):  
G. N. St.G. Ord ◽  
I. F. Cameron ◽  
D. S. Fensom
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic Permeability ◽  
Effect Of Ph ◽  
Transcellular Osmosis

The method of transcellular osmosis was used to compare the hydraulic permeability (LP) of Nitella membranes at different pH's. LP did not change when the pH ranged from 5.0 to 7.0 but dropped slightly when the pH was 4.4 or below. Tris(hydroxymethyl)aminomethane buffer and abscissic acid (ABA) both increased LP significantly.

Reduction in branch sapwood hydraulic permeability as a factor limiting survival of lower branches of lodgepole pine

2000 ◽  
Vol 30 (7) ◽  
pp. 1088-1095 ◽  
Author(s):  
Clark G Protz ◽  
Uldis Silins ◽  
Victor J Lieffers
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Hydraulic Permeability ◽  
Low Light ◽  
Sapwood Area ◽  
Canopy Trees ◽  
Closed Canopy ◽  
Eventual Death

Branch sapwood hydraulic permeability, tracheid size, and earlywood to latewood ratio of annual rings were examined in lower and upper branches of closed-canopy and open-grown lodgepole pine (Pinus contorta Dougl. ex Loud.) trees. Hydraulic permeability, expressed on either a leaf area or sapwood area basis, was lower in lower branches (0.16 × 10-5 and 5.82 × 10-5 m2, respectively) than upper branches (0.26 × 10-5 and 10.47 × 10-5 m2, respectively) and was related to narrower tracheids in the sapwood of lower branches. Earlywood/latewood ratio declined in the lower branches of shaded trees. The hydraulic conductivity of upper and lower branches in closed canopy trees was reduced by drilling small holes radially through the stem. Stomatal conductance was lower, and after a growing season there was greater foliage mortality in drilled lower crown branches than in similarly treated upper branches, suggesting that the hydraulic conductivity of lower branches was closer to the lower limit required to maintain foliage than in upper branches. These data suggest that high foliage mortality and eventual death of lower branches does not occur solely because of low light but also from reduced stomatal conductance and photosynthesis resulting from shade-initiated reductions in earlywood, tracheid diameter, and branch hydraulic conductivity.

Note on lack of effect of ethylene on water permeability, electroosmotic efficiency, or transcellular water flow of the plasma membranes in Nitella

1977 ◽  
Vol 55 (5) ◽  
pp. 615-616 ◽  
Author(s):  
D. S. Fensom ◽  
S. M. Ross
Keyword(s):  
Water Flow ◽  
Water Permeability ◽  
Plasma Membranes ◽  
Pond Water ◽  
Monovalent Cation ◽  
Hydraulic Permeability ◽  
Water Flows ◽  
Cation Permeability ◽  
Transcellular Osmosis ◽  
Permeation Properties

Ethylene (4.0 mM) in artificial pond water had no significant effect on three permeation properties of the plasma membranes of Nitella 2 h after addition. Neither the hydraulic permeability measured by transcellular osmosis, the passive monovalent cation permeability measured by electroosmosis, nor the 'active' transcellular water flows were altered appreciably by ethylene in solution.

scholarly journals Water Permeability of a Characean Internodal Cell with Special Reference to Its Polarity

1966 ◽  
Vol 19 (3) ◽  
pp. 399 ◽  
Author(s):  
M Tazawa ◽  
N Kamiya
Keyword(s):  
Hydraulic Conductivity ◽  
Special Reference ◽  
Cell Volume ◽  
Normal Level ◽  
Water Permeability ◽  
Forward Osmosis ◽  
External Concentration ◽  
Internodal Cell ◽  
Final Level ◽  
Transcellular Osmosis

Water permeability (hydraulic conductivity) of the Nitella internode was studied by means of transcellular osmosis with special reference to its polarity. It was shown that the change in turgor or in cell volume involved in transcellular osmosis is ahnost over within 5 sec after the onset of both forward and backward osmoses. What is different with respect to turgor between the two osmoses is its final level. In forward osmosis the turgor drops down to a definite level depending on the external concentration, while in backward osmosis the turgor invariably comes back to the normal level.

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