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Digitale Medien

An enzymic microassay for starch (1979)

JONES, M. G. K.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 2 (1979), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Abstract Conditions are described for measuring the starch content of plant tissues or extracts as glucose over the range from 10−7 mol to 10−14 mol. The method is based on the hydrolysis of gelatinized starch by amyloglucosidase; the glucose released is measured by reduction of NADP+ by coupled enzymic reactions.The NADPH is determined directly either spectrophotometrically or fluorimetrically, or after enzymic amplification. Amyloglucosidases were tested for contaminating enzymes which might degrade glucans other than starch, and a commercial preparation from Rhizopus niveus was found to be suitable for use without pretreatments. Glucose present in tissues and extracts may be measured and subtracted from starch values using appropriate blanks, or first destroyed by dilute alkali and heat. Addition of α-amylase to amyloglucosidase during starch hydrolysis was not found to increase percentage hydrolysis from the normal range of 86–99% from starches of different sources.The procedures described are rapid and several orders of magnitude more sensitive than current methods, and can be used to measure the starch content of single cells.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-3040.1979.tb00074.x

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Digitale Medien

“Action potentials” in nematode-induced plant transfer cells (1974)

Jones, M. G. K. ; Novacky, A. ; Dropkin, V. H.

Springer

Protoplasma 80 (1974), S. 401-405

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ISSN: 1615-6102

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary In a study of membrane potential properties of giant cells induced in the roots ofImpatiens balsamina by a rootknot nematode, trains of action potential-like fluctuations were recorded. Giant cells are multinucleate transfer cells, and it is suggested that the occurrence of action potentials may be characteristic of transfer cells.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01276355

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Digitale Medien

Multinucleate transfer cells induced in coleus roots by the root-knot nematode,Meloidogyne arenaria (1972)

Jones, M. G. K. ; Northcote, D. H.

Springer

Protoplasma 75 (1972), S. 381-395

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ISSN: 1615-6102

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The occurrence and position of wall protuberances in giant cells induced in coleus roots by the root-knot nematodeMeloidogyne arenaria is described, and the structure and function of giant cells is compared with that of syncytia induced by cyst-nematodes. Extensive protuberance development occurs on walls of giant cells adjacent to xylem vessels. Protuberances are less well developed next to sieve elements, and almost absent next to parenchyma cells. On walls between giant cells they occur on both sides or only one side. The formation of protuberances indicates that giant cells are multinucleate transfer cells. The position of protuberances marks the wall area where solutes enter the cell. Solutes are obtained from xylem and phloem elements, and the position of protuberances at the junction between giant cells and vascular elements indicates an extensive flow of solutes along cell walls. The observations support the hypothesis that wall protuberances form as a result of selective solute flow across the plasmalemma. No cell wall dissolution was observed, although wall gaps may occur between giant cells as a result of breakage during rapid cell expansion.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01282117

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Digitale Medien

Transmembrane potentials of parenchyma cells and nematode-induced transfer cells (1975)

Jones, M. G. K. ; Novacky, A. ; Dropkin, V. H.

Springer

Protoplasma 85 (1975), S. 15-37

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ISSN: 1615-6102

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary A comparison of transmembrane potential (pd) properties of parenchyma cells and giant transfer cells induced by a root-knot nematode in the roots ofImpatiens balsamina has been made. Apart from some differences in rate of response to a few treatments, parenchyma and giant cells had similar pd values; active and passive components of the pd (cyanide, azide); responses to total ion concentration, pH and potassium concentration; responses to protein synthesis inhibitors (puromycin, cycloheximide and actinomycin D) and responses to sugars. Both parenchyma cells and giant cells are depolarized by puromycin, cycloheximide and actinomycin D. The cells recover from the depolarization in the presence of cycloheximide, suggesting that this presumed protein synthesis inhibitor does not act in a straight-forward manner. The cells do not recover in the presence of puromycin or actinomycin D. Parenchyma cells and giant cells clearly have different metabolic rates and ion fluxes, but their pd responses are the same. This suggests that the pd does not reflect metabolic activity or ion fluxes of a cell, but is strictly controlled in itself. Part of this control may be via a feedback mechanism acting on an electrogenic pump. The depolarization caused by glucose is induced by aging the cells after excision. The effect is discussed in terms of an H+ dependent cotransport system and an ATPase permease system. The apparent normality of pd responses of nematode-induced giant transfer cells suggests that they may be a useful model system for experiments on higher plant cells.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01567756

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Digitale Medien

Transfer cells and nematode induced giant cells inHelianthemum (1976)

Jones, M. G. K. ; Gunning, B. E. S.

Springer

Protoplasma 87 (1976), S. 273-279

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ISSN: 1615-6102

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The morphology of wall ingrowths in xylem and phloem transfer cells inHelianthemum is different. It is possible to use nematode infection to induce the formation of giant cells which abut both xylem and phloem elements to test whether ingrowth morphology is controlled by the solutes presumed to be transported across the plasmalemma of the cells. This experiment has been done and it is found that although wall ingrowths develop against both xylem and phloem, the giant cells exhibit only the ingrowth structure characteristic of xylem transfer cells.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01623973

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