Elicitor-induced defence responses of a suspension-cultured woody plant (Larix decidua) and possible mechanisms of signal transduction

1997 ◽  
Vol 75 (8) ◽  
pp. 1243-1251 ◽  
Author(s):  
Martina Bach ◽  
Hanns Ulrich Seitz
Keyword(s):  
Signal Transduction ◽  
Fusarium Oxysporum ◽  
Woody Plant ◽  
Inositol Phosphates ◽  
Calcium Influx ◽  
Lignin Biosynthesis ◽  
Larix Decidua ◽  
Rapid Responses ◽  
A Cell ◽  
Defence Responses

Treatment of suspension-cultured larch cells (Larix decidua Mill.) with an elicitor derived from the cell wall of Fusarium oxysporum Schlecht. triggers very rapid defence responses like an oxidative burst and an increased calcium influx from the medium into the cell, all occurring within minutes after elicitation. These rapid responses are followed by a much slower set of changes like increased activities of phenylalanine ammonia-lyase and peroxidases and enhanced lignin biosynthesis. This paper describes both rapid and slow reactions of a cell culture derived from a woody plant to an elicitor from a facultative pathogen. Experiments concerning the transduction of the elicitor signal showed that the presence of calcium in the medium is indispensable for all elicitor responses of larch cells. It can be demonstrated that H2O2 is not a part of the signal chain. The importance of inositol phosphates and protein phosphorylation were studied using inhibitors. Neomycin, an inhibitor of the phosphoinositol pathway, blocked only the slower responses whereas staurosporine, an inhibitor of protein kinases, blocked both rapid and all the slower reactions. These results support the hypothesis that phosphorylation plays an important role even in very early stages of the signal transduction. Key words: elicitor, Fusarium oxysporum, H2O2, Larix decidua, lignin.

Eicosapentaenoic Acid Interferes with U46619-Stimulated Formation of Inositol Phosphates in Washed Rabbit Platelets

1989 ◽  
Vol 62 (04) ◽  
pp. 1116-1120 ◽  
Author(s):  
N Chetty ◽  
J D Vickers ◽  
R L Kinlough-Rathbone ◽  
M A Packham ◽  
J F Mustard
Keyword(s):  
Signal Transduction ◽  
Fatty Acid Composition ◽  
Eicosapentaenoic Acid ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Dense Granule ◽  
Detectable Change ◽  
Membrane Phospholipids ◽  
Rabbit Platelets ◽  
Stimulation Of

SummaryEicosapentaenoic acid (EPA) inhibits platelet responsiveness to aggregating agents. To investigate the reactions that are affected by EPA, we examined the effect of preincubating aspirintreated rabbit platelets with EPA on stimulation of inositol phosphate formation in response to the TXA2 analogue U46619. Stimulation of platelets with U46619 (0.5 μM) caused aggregation and slight release of dense granule contents; aggregation and release were inhibited by preincubation of the platelets with EPA (50 μM) for 1 h followed by washing to remove unincorporated EPA. Incubation with EPA (50 μM) for 1 h did not cause a detectable increase in the amount of EPA in the platelet phospholipids. When platelets were prelabelled with [3H]inositol stimulation with U46619 of control platelets that had not been incubated with EPA significantly increased the labelling of mos1tol phosphates. The increases in inositol phosphate labelling due to U46619 at 10 and 60 s were partially inhibited by premcubat10n of the platelets with 50 μM EPA. Since the activity of cyclo-oxygenase was blocked with aspirin, inhibition of inositol phosphate labelling in response to U46619 indicates either that there may be inhibition of signal transduction without a detectable change in the amount of EPA in platelet phospholipids, that changes in signal transduction require only minute changes in the fatty acid composition of membrane phospholipids, or that after a 1 h incubation with EPA, activation of phospholipase C is affected by a mechanism that is not directly related to incorporation of EPA.

Inositol phosphates, G-proteins and ras genes involved in chemotactic signal transduction of Dictyostelium

1988 ◽  
Vol 89 (2) ◽  
pp. 123-127
Author(s):  
PC Newell ◽  
GN Europe-Finner ◽  
NV Small ◽  
G Liu
Keyword(s):  
Signal Transduction ◽  
G Proteins ◽  
Inositol Phosphates ◽  
Ras Genes

scholarly journals Rapid Responses to Abiotic Stress: Priming the Landscape for the Signal Transduction Network

2019 ◽  
Vol 24 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Hannes Kollist ◽  
Sara I. Zandalinas ◽  
Soham Sengupta ◽  
Maris Nuhkat ◽  
Jaakko Kangasjärvi ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Abiotic Stress ◽  
Signal Transduction Network ◽  
Rapid Responses

Verapamil: a novel probe of surfactant secretion from rat type II pneumocytes

1989 ◽  
Vol 66 (3) ◽  
pp. 1304-1308 ◽  
Author(s):  
D. Warburton ◽  
L. Parton ◽  
S. Buckley ◽  
L. Cosico
Keyword(s):  
Inositol Phosphates ◽  
Calcium Influx ◽  
Concentration Effect ◽  
Type Ii ◽  
Calcium Efflux ◽  
Lactate Dehydrogenase Release ◽  
Type Ii Pneumocytes ◽  
Surfactant Secretion ◽  
Camp Formation ◽  
Stimulation Of

Surfactant from type II pneumocytes prevents the alveolar atelectasis found in both the neonatal and adult forms of respiratory distress syndrome. We have found that verapamil, a phenylalkene with calcium channel and alpha 1-receptor binding properties, has a multiphasic concentration effect on surfactant secretion from [3H]choline-labeled rat type II pneumocytes in culture. Verapamil (10(-8) M) caused a 24% stimulation of surfactant secretion, whereas an 8% inhibition was found at 10(-6) M and a 70% stimulation was found at 10(-4) M. Lactate dehydrogenase release occurred at 5 x 10(-4) M verapamil. Verapamil (10(-4) M) also produced a 100% increase in adenosine 3′5′-cyclic monophosphate (cAMP) in comparison with concentrations of less than or equal to 10(-6) M, an effect that could not be blocked by propranolol (10(-4) M). Verapamil (10(-6) M) increased the total formation of inositol phosphates (IP) by 23% in comparison with IP formation in control cells. Calcium influx was inhibited 15% by 10(-8) M verapamil and 37% by 10(-4) M verapamil. Calcium efflux was stimulated 44% by 10(-5) M verapamil. In combination with 50% effective concentrations (EC50) of terbutaline, phorbol ester, and ATP, the respective effects of verapamil (10(-4) M) on surfactant secretion were approximately additive. We conclude that verapamil has a novel multiphasic concentration effect on surfactant secretion, which appears to involve several signal transduction pathways including cAMP formation, IP formation, inhibition of calcium influx, and stimulation of calcium efflux.

Mechanism of action of luteinizing hormone-releasing hormone in rat ovarian cells

1989 ◽  
Vol 67 (8) ◽  
pp. 962-967 ◽  
Author(s):  
Peter C. K. Leung ◽  
Jian Wang ◽  
Kenneth G. Baimbridge
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Inositol Phosphates ◽  
Ionophore A23187 ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Ovarian Cells ◽  
Kinase C

The initial step in the signal transduction of luteinizing hormone-releasing hormone (LHRH) in rat ovarian cells is the hydrolysis of membrane polyphosphoinositides into inositol phosphates and 1,2-diacylglycerol. The former compounds, especially inositol 1,4,5-triphosphate, are known to cause the release of calcium from intracellular stores, while diacylglycerol is a potent activator of protein kinase C. LHRH causes a rapid and transient increase in intracellular concentrations of free calcium ions, by approximately 4.5-fold, in the majority of granulosa cells as assessed by fura-2 microspectrofluorimetry. Like LHRH, a calcium ionophore (A23187) and activators of protein kinase C attenuate the steroidogenic response of the cells to follicle-stimulating hormone, but enhance the formation of gonadotropin-induced prostaglandin formation. These results support the concept that stimulation of polyphosphoinositide hydrolysis is intimitely involved in the direct action of LHRH at the level of the ovary.Key words: signal transduction, calcium, protein kinase C, ovary, steroid hormones.

Perception Thresholding for Noise Removal in Micrographs of Cellular Tissues Acquired by Fluorescence Microscopy

2018 ◽  
Author(s):  
Saad Manzur ◽  
Md. Badiul Haque Shawon ◽  
Mahmuda Naznin ◽  
Tanvir R. Faisal
Keyword(s):  
Spatial Modeling ◽  
Woody Plant ◽  
Similarity Index ◽  
Hierarchical Structures ◽  
Noise Removal ◽  
Cellular Tissue ◽  
Experimental Procedure ◽  
Local Thresholding ◽  
Otsu’S Method ◽  
A Cell

Plant petioles and stems are hierarchical structures comprising cellular tissues in one or more intermediate hierarchies displaying quasi random to heterogeneous cellularity that governs the overall structural properties. Exact replication of natural cellular tissue leads to the investigation of mechanical properties at the microstructural level. However, the micrographs often display artifacts due to experimental procedure and prevent representative spatial modeling of the tissues. Existing methods such as local thresholding or global thresholding (Otsu’s method) fail to effectively remove the artifacts. Hence, an efficient algorithm is required that can effectively help to reconstruct the geometric models of tissue microstructures by removing the noise. In this work, perception-based thresholding that conceptually works like human brain in differentiating noise from the actual ones based on color is introduced to remove discrete (within a cell) or adjacent (to the cell boundaries) noise. A variety of image dataset of non-woody plant tissues were tested with the algorithm, and its effectiveness in eliminating noise was quantitatively compared with existing noise removal techniques by Bivariate Similarity Index. The bivariate metrics indicate an enhanced performance of the perception-based thresholding over other considered algorithms.

Sign in / Sign up

Export Citation Format

Share Document