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91.
The nerve growth factor: Thirty-five years later 总被引:15,自引:0,他引:15
Rita Levi-Montalcini 《Bioscience reports》1987,7(9):681-699
92.
J. -F. Laliberté I. L. Sun F. L. Crane M. J. Clarke 《Journal of bioenergetics and biomembranes》1987,19(1):69-81
Ammineruthenium(III) complexes have been found to act as electron acceptors for the transplasmalemma electron transport system of animal cells. The active complexes hexaammineruthenium(III), pyridine pentaammineruthenium(III), and chloropentaammineruthenium(III) range in redox potential (E
0) from 305 to –42 mV. These compounds also act as electron acceptors for the NADH dehydrogenase of isolated plasma membranes. Stimulation of HeLa cell growth, in the absence of calf serum, by these compounds provides evidence that growth stimulation by the transplasma membrane electron transport system is not entirely based on reduction and uptake of iron. 相似文献
93.
94.
95.
EFFECT OF MEDIA ON GROWTH AND INTERACTIONS BETWEEN A RANGE OF SOIL-BORNE GLASSHOUSE PATHOGENS AND ANTAGONISTIC FUNGI 总被引:10,自引:1,他引:9
JOHN M. WHIPPS 《The New phytologist》1987,107(1):127-142
96.
Differential thermal analysis indicated that the frost resistance of winter rape leaves ( Brassica napus L. var. oleifera L. cv. Gòrczanski), collected from plants grown in the cold (5/2°C), relies mainly on their ability to supercool to −9 to −11°C, i.e. consists in freezing avoidance. Initiation of ice formation in the cold-acclimated leaves resulted in the death of more than 50% of the cells as determined with a conductivity method. The development of freezing tolerance appeared to be an attribute of the second stage of plant hardening and was induced by the exposure of plants to a slightly subzero temperature (−5°C) for 18 h. Such a treatment brought about a sudden and persistent water potential decrease in the leaves, despite the fact that they had reabsorbed water from the medium prior to water potential measurements. Water potential changes were associated with a higher growth capability of the leaves as checked by determinations of disk area increments. It is suggested that the increased frost tolerance of the cold-grown winter rape leaves, subjected to subfreezing temperature, is related to the decreased water potential of the tissue caused by changes in turgor and/or in osmotic pressures of the cells. 相似文献
97.
The function of the epidermis in auxinmediated elongation growth of maize (Zea mays L.) coleoptile segments was investigated. The following results were obtained: i) In the intact organ, there is a strong tissue tension produced by the expanding force of the inner tissues which is balanced by the contracting force of the outer epidermal wall. The compression imposed by the stretched outer epidermal wall upon the inner tissues gives rise to a wall-pressure difference which can be transformed into a water-potential difference between inner tissues and external medium (water) by removal of the outer epidermal wall. ii) Peeled segments fail to respond to auxin with normal growth. The plastic extensibility of the inner-tissue cell walls (measured with a constant-load extensiometer using living segments) is not influenced by auxin (or abscisic acid) in peeled or nonpeeled segments. It is concluded that auxin induces (and abscisic acid inhibits) elongation of the intact segment by increasing (decreasing) the extensibility specifically in the outer epidermal wall. In addition, tissue tension (and therewith the pressure acting on the outer epidermal wall) is maintained at a constant level over several hours of auxin-mediated growth, indicating that the inner cells also contribute actively to organ elongation. However, this contribution does not involve an increase of cell-wall extensibility, but a continuous shifting of the potential extension threshold (i.e., the length to which the inner tissues would extend by water uptake after peeling) ahead of the actual segment length. Thus, steady growth involves the coordinated action of wall loosening in the epidermis and regeneration of tissue tension by the inner tissues. iii) Electron micrographs show the accumulation of striking osmiophilic material (particles of approx. 0.3 m diameter) specifically at the plasma membrane/cell-wall interface of the outer epidermal wall of auxin-treated segments. iv) Peeled segments fail to respond to auxin with proton excretion. This is in contrast to fusicoccin-induced proton excretion and growth which can also be readily demonstrated in the absence of the epidermis. However, peeled and nonpeeled segments show the same sensitivity to protons with regard to the induction of acid-mediated in-vivo elongation and cell-wall extensibility. The observed threshold at pH 4.5–5.0 is too low to be compatible with a second messenger function of protons also in the growth response of the inner tissues. Organ growth is described in terms of a physical model which takes into account tissue tension and extensibility of the outer epidermal wall as the decisive growth parameters. This model states that the wall pressure increment, produced by tissue tension in the outer epidermal wall, rather than the pressure acting on the inner-tissue walls, is the driving force of growth.Abbreviations and symbols
E
el, E
pl
elastic and plastic in-vitro cell-wall extensibility, respectively
-
E
tot
E
el+E
pl
- FC
fusicoccin
- IAA
indole-3-acetic acid
- IT
inner tissue
- ITW
inner-tissue walls
- OEW
outer epidermal wall
-
osmotic pressure
-
P
wall pressure
-
water potential 相似文献
98.
For three acid soils from Santa Catarina, Brazil, lime application and time of incubation with lime had little effect on the
adsorption of added phosphorus. In two soils with high contents of exchangeable aluminium, solution P and isotopically exchangeable
P were decreased by incubating with lime for 1 month: phosphorus was probably adsorbing on freshly precipitated aluminium
hydrous oxides. In one soil with less exchangeable aluminium, P in solution was increased by liming. After 23 months lime
increased solution and exchangeable P possibly due to crystallization of aluminium hydrous oxides reducing the number of sites
for P adsorption. All these changes were however small.
In a pot experiment, lime and phosphorus markedly increased barley shoot and root dry matter and P uptake. Although liming
reduced P availability measured by solution P, isotopically exchangeable P and resin extractable P, it increased phosphorus
uptake by reducing aluminium toxicity and promoting better root growth. The soil aluminium saturation was reduced by liming,
but the concentration of aluminium in roots changed only slightly. The roots accumulated aluminium without apparently being
damaged. 相似文献
99.
Summary Cucumber seedlings were grown in a Portsmouth soil-sand system to study how varying soil clay and organic matter content might
modify cucumber seedling response to ferulic acid, a reported allelopathic agent. Leaf area expansion of cucumber seedlings,
soil respiration, and soil solution concentrations of ferulic acid were monitored. Leaf area, mean absolute rates of leaf
expansion, and shoot dry weight of cucumber seedlings were significantly reduced by ferulic acid concentrations ranging from
10 to 70 μg/g dry soil. Ferulic acid was applied every other day, since it rapidly disappeared from soil solution as a result
of retention by soil particles, utilization by microbes and/or uptake by roots. The amount of ferulic acid retained (i.e., adsorbed, polymerized,etc.) by soil particles appeared to be secondary to microbial utilization and/or uptake by roots. Varying clay (5.3 to 9.8 g/cup)
and organic matter (2.0 to 0.04g/cup) contents of the soil appeared to have little impact on the disappearance of ferulic
acid from soil solution under “ideal” growth conditions for cucumber seedlings unless larger amounts of ferulic acid were
added to the soil; in this case 200 μg/g. The addition of ferulic acid to the soil materials substantially increased the activity
of the soil microbes. This latter conclusion is based on recovery of ferulic acid from soil solution and soil respiration
measurements.
Paper No. 10347 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, N C 27695-7601. The use
of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the product
named, nor criticism of similar ones not mentioned. 相似文献
100.
Relation between electrokinetic potentials and growth in callus cultures ofTrigonella foenum-graecum
Callus cultures ofTrigonella foenum-graecum were initiated from radicle or cotyledon portions of seedlings and young leaves and maintained on modified 1-B5 medium. The
callus mass was disaggregated by mechanical agitation and the discrete cells thus obtained were used to measure their electrokinetic
potential. Studies pertaining to the effects of ageing on electrokinetic potential and growth index revealed a relationship
between these two parameters. Thus, the rate of change of electrokinotie potential with age could be employed as a parameter
to study the growth kinetics of cells in callus cultures. 相似文献