Senescence-Related Changes in ATP-Dependent Uptake of Calcium into Microsomal Vesicles from Carnation Petals

Paliyath, Gopinadhan; Thompson, John E.

doi:10.1104/pp.88.2.295

Cited by 21 publications

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“…5) are likely to result from an inability of senescent cells to regulate their [Ca 24 ] cyt , as suggested previously for senescing carnation petals (Paliyath and Thompson, 1988). Indeed, a striking difference in the way nonsenescent and senescent cells cope with the excess Ca 2+ could be observed.…”

Section: Discussionsupporting

confidence: 51%

“…Stimulus-induced changes in [Ca2+Icyt may be transient, sustained, or oscillatory, and the time required for full response varies from a few seconds to severa1 hours (Bush, 1995). A transient increase in [Ca2+Icyt may result either from a decrease in plasma membrane Ca2+-ATPase activity (Paliyath and Thompson, 1988) or from the opening of Ca2+ channels in the cell membranes (Schroeder and Hedrich, 1989).…”

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confidence: 99%

“…Further evidence for the involvement of [Ca'+lcyt in the processes leading to senescence was reported for leaves of cowpea (Savithramma and Swamy, 1989), oat (Dreier, 1990), rice (Huang et al, 1990;Chou and Kao, 1992), corn Kao, 1992a, 1992b), and parsley (Petroselinum crispum) (S. Philosoph-Hadas, R. Sabato, R. Ronen, S. Lurie, and S. Meir, unpublished data). In addition, the loss of Ca2+ transport capability has been shown to be an early event in the senescent stages of carnation flowers, which is likely to result in higher than normal levels of [Ca2+Icyt and therefore the facilitation of senescence (Paliyath and Thompson, 1988). In tomato and apple fruits stage-specific changes in Ca2+-dependent protein phosphorylation, which disappear completely at the onset of ripening and senescence, have been observed (Poovaiah and Reddy, 1987).…”

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Increases in Cytosolic Ca2+ in Parsley Mesophyll Cells Correlate with Leaf Senescence

et al. 1997

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l h e ability to maintain the cytoplasmic Ca2+ concentration ([Ca2+],,,) at homeostatic levels has been examined during leaf senescence in detached parsley (Petroselinum crispum) leaves. Fluorescence ratiometric imaging of mesophyll cells isolated from parsley leaves at various senescence stages and loaded with the CaZ+ indicator fura-2 has revealed a distinct elevation of [Ca2+lCyl, which was positively correlated with the progress of leaf senescence. This initial increase of [Caz+lcyy which was first observed in cells iso- Senescence is a deteriorative process that is associated with a wide range of biochemical changes. Most notable in green leaves is the decrease of Chl content, which is accompanied by a parallel degradation of polar lipids from the matrix of the thylakoid membrane (Thomas and Stoddart, 1980;Thomas, 1986;Meir and Philosoph-Hadas, 1995) and by proteolysis (Thimann, 1985;Philosoph-Hadas et al., 1994). One of the factors that may participate in the regulation of leaf senescence is [Ca2+C],yt (Leshem, 1987), the regulation of which is considered an essential cell function in a11 eukaryotes (Bush, 1995). Cellular Ca2+ homeostasis is normally maintained at submicromolar levels by an ensemble of membrane-

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Section: Discussionsupporting

confidence: 51%

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confidence: 99%

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Increases in Cytosolic Ca2+ in Parsley Mesophyll Cells Correlate with Leaf Senescence

et al. 1997

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“…Protein was measured by the method of Bradford (3) using bovine serum albumin as a standard. Density gradient fractionation of the microsomal membranes and measurements of marker enzymes were carried out as described previously (23 The water-soluble radiolabeled metabolites formed from choline-labeled phosphatidylcholine by microsomal membranes were measured as described previously (21). The reaction mixture contained 4 kBq of L-dipalmitoyl[cholinemethyl-3H] phosphatidylcholine (2.1 TBq mmol-', New England Nuclear) and 600 ,ug of microsomal membrane protein in a final volume of 1 mL.…”

Section: Materials and Methods Plant Materials And Fractionationmentioning

confidence: 99%

Characteristics of a Membrane-Associated Lipoxygenase in Tomato Fruit

Todd¹,

Paliyath²,

Thompson³

1990

Plant Physiol.

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Microsomal membranes isolated from the pericarp of maturegreen tomato (Lycopersicon esculentum) fruit rapidly metabolize exogenous radiolabeled linoleic acid into fatty acid oxidation products at 22°C. The reaction is strongly inhibited by n-propyl gallate, an inhibitor of lipoxygenase. The membranes also rapidly metabolize 16:0/18:2* phosphatidylcholine into radiolabeled oxidation products that comigrate on TLC plates with those formed from free linoleic acid. At 300C, the formation of fatty acid oxidation products from 16:0/18:2* phosphatidylcholine is slower, and there is an initial accumulation of radiolabeled linoleic acid that is not evident at 220C, which can be attributed to the action of lipolytic acyl hydrolase. Radiolabeled phosphatidic acid and diacylglycerol are also formed during metabolism of 16:0/18:2* phosphatidylcholine by the microsomal membranes, and there is no breakdown of either linoleic acid or phosphatidylcholine by heat-denatured membranes. When Triton X-100 treated membranes were used, the same pattems of metabolite formation from radiolabeled linoleic acid and 16:0/18:2* phosphatidylcholine were observed. Thus, the enzymes mediating the breakdown of these radiolabeled compounds appear to be tightly associated with the membranes. Collectively, the data indicate that there is a lipoxygenase associated with microsomal membranes from tomato fruit that utilizes free fatty acid substrate released from phospholipids. The microsomal lipoxygenase is strongly active over a pH range of 4.5 to 8.0, comprises approximately 38% of the total (microsomal plus soluble) lipoxygenase activity in the tissue, has an apparent Km of 0.52 millimolar and an apparent V,,. of 0.186 millimoles per minute per milligram of protein. The membranous enzyme also cross-reacts with polyclonal antibodies raised against soybean lipoxygenase-1 and has an apparent molecular mass of 100 kilodaltons.Lipoxygenase (EC 1.13.11.12) is a dioxygenase that catalyzes the peroxidation of fatty acids containing a cis,cis-l1,4-pentadiene configuration. Distinguishable isozymes of lipoxygenase have been described for a number of tissues in different plant species (8) and the best characterized of these are the three isozymes of soybean known as lipoxygenase-1, -2, and -3 (18 94, 1990 from lipoxygenase-1 of soybean (26). In the present study, we describe a lipoxygenase activity associated with microsomal membranes from tomato fruit that comprises 38% ofthe total (microsomal plus soluble) lipoxygenase activity in the tissue, appears to utilize free fatty acid released from membrane phospholipids as substrate and is immunologically related to its soluble counterpart and to soybean lipoxygenase-1. MATERIALS AND METHODS Plant Material and FractionationTomato fruit (Lycopersicon esculentum L. cv Caruso) were grown under greenhouse conditions and harvested at the mature-green stage. Pericarp tissue was cut into small pieces (~10 mm3) and suspended (-1 g/mL) in cold homogenizing buffer (100 mm Mops, 10 mM EGTA, and 7% sucrose at pH 7...

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“…Sucrose density gradient fractionation of the microsomal membranes and measurements of marker enzyme activities (vanadate-sensitive ATPase for plasma membrane and rotenone-insensitive NADHCyt c reductase for endoplasmic reticulum) were carried out as described previously (12). Chl was quantified by A652, and carotenoids were measured as described by Britton (3).…”

Section: Membrane Fractionationmentioning

confidence: 99%

Purification and Partial Characterization of a Membrane-Associated Lipoxygenase in Tomato Fruit

Bowsher

Ferrie²,

Ghosh³

et al. 1992

Plant Physiol.

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Membrane-associated lipoxygenase from green tomato (Lycopersicon esculentum L. cv Caruso) fruit has been purified 49-fold to a specific activity of 8.3 ,mol *min' . mg-' of protein by solubilization of microsomal membranes with Triton X-100, followed by anion-exchange and size-exclusion chromatography. The apparent molecular mass of the enzyme was estimated to be 97 and 102 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, respectively. The purified membrane lipoxygenase preparation consisted of a single major band following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which cross-reacts with immunoserum raised against soluble soybean lipoxygenase 1. It has a pH optimum of 6.5, an apparent Km of 6.2 Mm, and Vm,x of 10.3 jAmol-min-' mg-' of protein with linoleic acid as substrate. Corresponding values for the partially purified soluble lipoxygenase from tomato are 3.8 Mm and 1.3 Amol min-'.mg-' of protein, respectively. Thus, the membraneassociated enzyme is kinetically distinguishable from its soluble counterpart. Sucrose density gradient fractionation of the isolated membranes indicated that the membrane-associated lipoxygenase sediments with thylakoids. A lipoxygenase band with a corresponding apparent mol wt of 97,000 was identified immunologically in sodium dodecyl sulfate-polyacrylamide gel electrophoresis-resolved proteins of purified thylakoids prepared from intact chloroplasts isolated from tomato leaves and fruit.The predominant mechanism for fatty acid catabolism is fl-oxidation, which occurs in mitochondria or glyoxysomes. Although this pathway metabolizes most of the fatty acids derived from stored fats and oils, several other routes are utilized for the oxidation of specialized fatty acids. One of these alternative pathways involves the enzyme lipoxygenase (EC 1.13.11.12), which catalyzes the oxidation of a class of unsaturated fatty acids having a cis,cis-1,4-pentadiene structure. These fatty acids are primarily present as constituents of membrane phospholipids. The existence of this enzyme 'This work was supported by grants to S

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Senescence-Related Changes in ATP-Dependent Uptake of Calcium into Microsomal Vesicles from Carnation Petals

Cited by 21 publications

References 26 publications

Increases in Cytosolic Ca2+ in Parsley Mesophyll Cells Correlate with Leaf Senescence

Increases in Cytosolic Ca2+ in Parsley Mesophyll Cells Correlate with Leaf Senescence

Characteristics of a Membrane-Associated Lipoxygenase in Tomato Fruit

Purification and Partial Characterization of a Membrane-Associated Lipoxygenase in Tomato Fruit

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