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Richard G F Visser - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of enzymes involved in sucrose to Hexose Phosphate conversion during stolon to tuber transition of potato
Physiologia Plantarum, 2002Co-Authors: Niek J G Appeldoorn, Lidiya V Sergeeva, Dick Vreugdenhil, Linus H W Van Der Plas, Richard G F VisserAbstract:An in situ study of enzymes involved in sucrose to Hexose-Phosphate conversion during in vitro stolon-to-tuber transition of potato (Solanum tuberosum L. cv. Bintje) was employed to follow developmental changes in spatial patterns. In situ activity of the respective enzymes was visualized by specific activity-staining techniques and they revealed distinct spatially and developmentally regulated patterns. Two of the enzymes studied were also subject to in situ investigations at the transcriptional level. During the stages of stolon formation high hexokinase (EC 2.7.1.1) and acid (cell wall-bound) invertase (EC 3.2.1.26) activities were restricted to the mitotically active (sub)apical region, suggesting a possible importance of these enzymes for cell division. At the onset of tuberization sucrose synthase (EC 2.4.1.13) and fructokinase (EC 2.7.1.4) were strongly induced (visualized at transcriptional and translational level) and the acid invertase activities disappeared from the swelling subapical region as expected. The high degree of similarity in the spatial pattern and the temporal induction of sucrose synthase and fructokinase suggests a tightly co-ordinated coarse (up)regulation, which may be subject to a sugar-modulated mechanism(s) by which genes involved in the metabolic sucrose-starch converting potential are co-ordinately regulated during tuber growth. The overall activity of uridine-5-diphosphoglucose pyrophosphorylase (EC 2.7.7.9) was present in all tissues during stolon and tuber development, implying that its coarse control is not subject to (in)direct developmental regulation.
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Developmental changes in enzymes involved in the conversion of Hexose Phosphate and its subsequent metabolites during early tuberization of potato
Plant Cell & Environment, 1999Co-Authors: Niek J G Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, Linus H W Van Der PlasAbstract:A highly synchronized in vitro tuberization system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of Hexose Phosphates and related products during stolon-to-tuber transition of potato (Solanum tuberosum L.). At tuberization the activity of enzymes involved in glycolysis and the oxidative pentose Phosphate pathway (OPPP) showed a small but clear increase. This increase reflects a higher capacity of respiratory(-related) metabolism, presumably due to the onset of rapid cell division in the apical part of the tuberizing stolon. During the phase of successive tuber growth these enzymes decreased in activity, suggesting that the concomitant massive starch accumulation is not accompanied by a large increase in respiration. A high degree of positive correlation between the activities of these enzymes could be observed, implying that the level of respiratory metabolism-related enzymes is co-ordinately regulated by the same mechanism of coarse control. The activity pattern of pyroPhosphate:fructose-6-Phosphate phosphotransferase (PFP) showed no developmental change and does not resemble the activity pattern of the enzymes participating in respiratory(-related) metabolism. Instead, its level of activity is very likely the result of metabolic regulation. The level of the content of the metabolites UDP-glucose (UDPGlc) and glucose-6-Phosphate (Glc6P) decreased after the onset of tuberization. This decline indicates that tuber induction is not accompanied by an appreciable increase in the level of the cytosolic Hexose Phosphate (Hexose-P) content but that it rather remains on a low level, which might be a prerequisite in order to maintain a high net rate of sucrose degradation during tuber development. In contrast to UDPGlc and Glc6P, the content of fructose-1,6-bisPhosphate (Fru1,6bisP) showed an increase after tuber induction. The overall activities of ADP-glucose pyrophosphorylase (AGPase) and starch phosphorylase (STP) both showed a large increase after tuber initiation, which is consistent with their presumed role in the process of starch synthesis and accumulation during rapid tuber growth.
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Developmental changes of enzymes involved in conversion of sucrose to Hexose-Phosphate during early tuberisation of potato.
Planta, 1997Co-Authors: N.j.g. Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, L H W Van Der PlasAbstract:A highly synchronised in-vitro tuberisation system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of sucrose to Hexose-Phosphates during stolon-to-tuber transition of potato (Solanum tuberosum L.). Two different non-tuberising systems were included to distinguish between changes that are or are not tuber-specific. At tuberisation the activity of soluble acid invertase decreased (13-fold) and of sucrose synthase increased (12-fold). The activity of both enzymes remained unchanged in the non-tuberising treatments. Based on the opposite patterns and large difference in activity of these two sucrolytic enzymes, we conclude that sucrose synthase constitutes the predominant route of sucrose breakdown after tuber initiation. During the period before tuberisation, the activity of cell-wall-bound invertase and of hexokinase showed a highly positive correlation (r 2 = 0.96 in all the three treatments, suggesting coordinated coarse control of both enzyme activities. After the onset of tuberisation cell-wall-bound invertase activity decreased to a very low level, a change not observed in the non-tuberising systems, indicating that cell-wall-bound invertase is presumably not involved in the unloading mechanism and/or short-distance transport of sucrose within the perimedulla of growing tubers. The overall activity of fructokinase and of hexokinase both showed a fourfold increase after tuber initiation, but remained unchanged in the non-tuberising systems. The increase of fructokinase suggests that the phosphorylation of fructose by fructokinase down-regulates the cytosolic fructose content in order to maintain a high sucrose-synthase-catalysed net flux of sucrose to phosphorylated Hexoses during rapid tuber growth. The increase of total glucose-phosphorylating potential could be a response to the tuberisation-related starch accumulation process. The activity of UDP-glucose pyrophosphorylase showed no developmental change. The level of UDP-glucose pyrophosphorylase activity is very likely the result of metabolic regulation.
Linus H W Van Der Plas - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of enzymes involved in sucrose to Hexose Phosphate conversion during stolon to tuber transition of potato
Physiologia Plantarum, 2002Co-Authors: Niek J G Appeldoorn, Lidiya V Sergeeva, Dick Vreugdenhil, Linus H W Van Der Plas, Richard G F VisserAbstract:An in situ study of enzymes involved in sucrose to Hexose-Phosphate conversion during in vitro stolon-to-tuber transition of potato (Solanum tuberosum L. cv. Bintje) was employed to follow developmental changes in spatial patterns. In situ activity of the respective enzymes was visualized by specific activity-staining techniques and they revealed distinct spatially and developmentally regulated patterns. Two of the enzymes studied were also subject to in situ investigations at the transcriptional level. During the stages of stolon formation high hexokinase (EC 2.7.1.1) and acid (cell wall-bound) invertase (EC 3.2.1.26) activities were restricted to the mitotically active (sub)apical region, suggesting a possible importance of these enzymes for cell division. At the onset of tuberization sucrose synthase (EC 2.4.1.13) and fructokinase (EC 2.7.1.4) were strongly induced (visualized at transcriptional and translational level) and the acid invertase activities disappeared from the swelling subapical region as expected. The high degree of similarity in the spatial pattern and the temporal induction of sucrose synthase and fructokinase suggests a tightly co-ordinated coarse (up)regulation, which may be subject to a sugar-modulated mechanism(s) by which genes involved in the metabolic sucrose-starch converting potential are co-ordinately regulated during tuber growth. The overall activity of uridine-5-diphosphoglucose pyrophosphorylase (EC 2.7.7.9) was present in all tissues during stolon and tuber development, implying that its coarse control is not subject to (in)direct developmental regulation.
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Developmental changes in enzymes involved in the conversion of Hexose Phosphate and its subsequent metabolites during early tuberization of potato
Plant Cell & Environment, 1999Co-Authors: Niek J G Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, Linus H W Van Der PlasAbstract:A highly synchronized in vitro tuberization system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of Hexose Phosphates and related products during stolon-to-tuber transition of potato (Solanum tuberosum L.). At tuberization the activity of enzymes involved in glycolysis and the oxidative pentose Phosphate pathway (OPPP) showed a small but clear increase. This increase reflects a higher capacity of respiratory(-related) metabolism, presumably due to the onset of rapid cell division in the apical part of the tuberizing stolon. During the phase of successive tuber growth these enzymes decreased in activity, suggesting that the concomitant massive starch accumulation is not accompanied by a large increase in respiration. A high degree of positive correlation between the activities of these enzymes could be observed, implying that the level of respiratory metabolism-related enzymes is co-ordinately regulated by the same mechanism of coarse control. The activity pattern of pyroPhosphate:fructose-6-Phosphate phosphotransferase (PFP) showed no developmental change and does not resemble the activity pattern of the enzymes participating in respiratory(-related) metabolism. Instead, its level of activity is very likely the result of metabolic regulation. The level of the content of the metabolites UDP-glucose (UDPGlc) and glucose-6-Phosphate (Glc6P) decreased after the onset of tuberization. This decline indicates that tuber induction is not accompanied by an appreciable increase in the level of the cytosolic Hexose Phosphate (Hexose-P) content but that it rather remains on a low level, which might be a prerequisite in order to maintain a high net rate of sucrose degradation during tuber development. In contrast to UDPGlc and Glc6P, the content of fructose-1,6-bisPhosphate (Fru1,6bisP) showed an increase after tuber induction. The overall activities of ADP-glucose pyrophosphorylase (AGPase) and starch phosphorylase (STP) both showed a large increase after tuber initiation, which is consistent with their presumed role in the process of starch synthesis and accumulation during rapid tuber growth.
Martine Crasnier - One of the best experts on this subject based on the ideXlab platform.
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regulation of escherichia coli adenylate cyclase activity during Hexose Phosphate transport
Microbiology, 1996Co-Authors: Valerie Dumay, Antoine Danchin, Martine CrasnierAbstract:In Escherichia coli cAMP levels vary with the carbon source used in the culture medium. These levels are dependent on the cellular concentration of phosphorylated EnzymeIIAglc, a component of the glucose-phosphotransferase system, which activates adenylate cyclase (AC). When cells are grown on glucose 6-Phosphate (Glc6P), the cAMP level is particularly low. In this study, we investigated the mechanism leading to the low cAMP level when Glc6P is used as the carbon source, i.e. the mechanism preventing the activation of AC by phosphorylated EnzymellAglc. Glc6P is transported via the Uhp system which is inducible by extracellular Glc6P. The Uhp system comprises a permease UhpT and three proteins UhpA, UhpB and UhpC which are necessary for uhpT gene transcription. Controlled expression of UhpT in the absence of the regulatory proteins (UhpA, UhpB and UhpC) allowed us to demonstrate that (i) the Uhp regulatory proteins do not prevent the activation of AC by direct interaction with EnzymellAglc and (ii) an increase in the amount of UhpT synthesized (corresponding to an increase in the amount of Glc6P transported) correlates with a decrease in the cAMP level. We present data indicating that Glc6P per se or its degradation is unlikely to be responsible for the low cAMP level. It is concluded that the level of cAMP in the cell is determined by the flux of Glc6P through UhpT.
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role of the phosphotransferase system in escherichia coli strains deficient in Hexose Phosphate transport
Fems Microbiology Letters, 1994Co-Authors: Valerie Dumay, Martine CrasnierAbstract:Abstract In Escherichia coli , glucose 6-Phosphate is transported via the Uhp system which is inducible by glucose 6-Phosphate. We showed that, in a uhp -deficient strain, glucose 6-Phosphate was dephosphorylated in the periplasm and that the resulting glucose was subsequently transported into the cells via the phosphotransferase system. The uptake of glucose generated from glucose 6-Phosphate allowed the bacteria to produce an increased level cAMP compared to cells grown on non-limiting concentrations of glucose.
Niek J G Appeldoorn - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of enzymes involved in sucrose to Hexose Phosphate conversion during stolon to tuber transition of potato
Physiologia Plantarum, 2002Co-Authors: Niek J G Appeldoorn, Lidiya V Sergeeva, Dick Vreugdenhil, Linus H W Van Der Plas, Richard G F VisserAbstract:An in situ study of enzymes involved in sucrose to Hexose-Phosphate conversion during in vitro stolon-to-tuber transition of potato (Solanum tuberosum L. cv. Bintje) was employed to follow developmental changes in spatial patterns. In situ activity of the respective enzymes was visualized by specific activity-staining techniques and they revealed distinct spatially and developmentally regulated patterns. Two of the enzymes studied were also subject to in situ investigations at the transcriptional level. During the stages of stolon formation high hexokinase (EC 2.7.1.1) and acid (cell wall-bound) invertase (EC 3.2.1.26) activities were restricted to the mitotically active (sub)apical region, suggesting a possible importance of these enzymes for cell division. At the onset of tuberization sucrose synthase (EC 2.4.1.13) and fructokinase (EC 2.7.1.4) were strongly induced (visualized at transcriptional and translational level) and the acid invertase activities disappeared from the swelling subapical region as expected. The high degree of similarity in the spatial pattern and the temporal induction of sucrose synthase and fructokinase suggests a tightly co-ordinated coarse (up)regulation, which may be subject to a sugar-modulated mechanism(s) by which genes involved in the metabolic sucrose-starch converting potential are co-ordinately regulated during tuber growth. The overall activity of uridine-5-diphosphoglucose pyrophosphorylase (EC 2.7.7.9) was present in all tissues during stolon and tuber development, implying that its coarse control is not subject to (in)direct developmental regulation.
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Developmental changes in enzymes involved in the conversion of Hexose Phosphate and its subsequent metabolites during early tuberization of potato
Plant Cell & Environment, 1999Co-Authors: Niek J G Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, Linus H W Van Der PlasAbstract:A highly synchronized in vitro tuberization system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of Hexose Phosphates and related products during stolon-to-tuber transition of potato (Solanum tuberosum L.). At tuberization the activity of enzymes involved in glycolysis and the oxidative pentose Phosphate pathway (OPPP) showed a small but clear increase. This increase reflects a higher capacity of respiratory(-related) metabolism, presumably due to the onset of rapid cell division in the apical part of the tuberizing stolon. During the phase of successive tuber growth these enzymes decreased in activity, suggesting that the concomitant massive starch accumulation is not accompanied by a large increase in respiration. A high degree of positive correlation between the activities of these enzymes could be observed, implying that the level of respiratory metabolism-related enzymes is co-ordinately regulated by the same mechanism of coarse control. The activity pattern of pyroPhosphate:fructose-6-Phosphate phosphotransferase (PFP) showed no developmental change and does not resemble the activity pattern of the enzymes participating in respiratory(-related) metabolism. Instead, its level of activity is very likely the result of metabolic regulation. The level of the content of the metabolites UDP-glucose (UDPGlc) and glucose-6-Phosphate (Glc6P) decreased after the onset of tuberization. This decline indicates that tuber induction is not accompanied by an appreciable increase in the level of the cytosolic Hexose Phosphate (Hexose-P) content but that it rather remains on a low level, which might be a prerequisite in order to maintain a high net rate of sucrose degradation during tuber development. In contrast to UDPGlc and Glc6P, the content of fructose-1,6-bisPhosphate (Fru1,6bisP) showed an increase after tuber induction. The overall activities of ADP-glucose pyrophosphorylase (AGPase) and starch phosphorylase (STP) both showed a large increase after tuber initiation, which is consistent with their presumed role in the process of starch synthesis and accumulation during rapid tuber growth.
Dick Vreugdenhil - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of enzymes involved in sucrose to Hexose Phosphate conversion during stolon to tuber transition of potato
Physiologia Plantarum, 2002Co-Authors: Niek J G Appeldoorn, Lidiya V Sergeeva, Dick Vreugdenhil, Linus H W Van Der Plas, Richard G F VisserAbstract:An in situ study of enzymes involved in sucrose to Hexose-Phosphate conversion during in vitro stolon-to-tuber transition of potato (Solanum tuberosum L. cv. Bintje) was employed to follow developmental changes in spatial patterns. In situ activity of the respective enzymes was visualized by specific activity-staining techniques and they revealed distinct spatially and developmentally regulated patterns. Two of the enzymes studied were also subject to in situ investigations at the transcriptional level. During the stages of stolon formation high hexokinase (EC 2.7.1.1) and acid (cell wall-bound) invertase (EC 3.2.1.26) activities were restricted to the mitotically active (sub)apical region, suggesting a possible importance of these enzymes for cell division. At the onset of tuberization sucrose synthase (EC 2.4.1.13) and fructokinase (EC 2.7.1.4) were strongly induced (visualized at transcriptional and translational level) and the acid invertase activities disappeared from the swelling subapical region as expected. The high degree of similarity in the spatial pattern and the temporal induction of sucrose synthase and fructokinase suggests a tightly co-ordinated coarse (up)regulation, which may be subject to a sugar-modulated mechanism(s) by which genes involved in the metabolic sucrose-starch converting potential are co-ordinately regulated during tuber growth. The overall activity of uridine-5-diphosphoglucose pyrophosphorylase (EC 2.7.7.9) was present in all tissues during stolon and tuber development, implying that its coarse control is not subject to (in)direct developmental regulation.
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the triose Hexose Phosphate cycle and the sucrose cycle in carrot daucus carota l cell suspensions are controlled by respiration and ppi fructose 6 Phosphate phosphotransferase
Journal of Plant Physiology, 2000Co-Authors: J Krook, Dick Vreugdenhil, K A E Van T Slot, C Dijkema, L H W Van Der PlasAbstract:Summary Short-term labelling was applied to two different lines of Daucus carota L. cell suspensions by feeding [1-13C]-glucose. The A10-line, containing 10 % proembryogenic masses (PEMs) and 90 % large, vacuolated cells (VACs), showed a 2 times higher label exchange from C-1 to C-6 carbons within sucrose and Hexoses than the A+ -line, containing 80 % PEMs. This label exchange is known to be caused by cycling of carbon from Hexose Phosphates to triose Phosphates and vice versa, in which ATP-dependent phosphofructokinase (PFK, EC 2.7.1.11) catalyses the glycolytic reaction and PPi-dependent phosphofructokinase (PFP, EC 2.7.1.90) the gluconeogenetic reaction. The ratio of extractable PFP/PFK was 3 times higher in the A10-line compared to the A+-line. However, PEMs and VACs from one line showed identical PFP/PFK ratios and identical label exchange. It is concluded that the level of PFP is genetically determined and that this level influences the amount of label exchange from C-1 to C-6 carbons in Hexoses and sucrose in Daucus cells. High levels of the reversible enzyme PFP might give plants the advantage to respond adequately to quickly changing demands for substrates for either glycolytic or gluconeogenetic reactions. Both triose-Hexose Phosphate cycling and respiration were higher when suspensions were aerated with 100% O2 instead of 6% O2. It is concluded that high respiratory activity stimulated both the flow of Hexose Phosphates into the respiratory pathway and the back-flow from triose to Hexose Phosphates. However, total labelled sucrose was at least two times higher at 6% O2 than at 100% O2, indicating that more Hexose Phosphates were available for sucrose synthesis at 6% O2.
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Developmental changes in enzymes involved in the conversion of Hexose Phosphate and its subsequent metabolites during early tuberization of potato
Plant Cell & Environment, 1999Co-Authors: Niek J G Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, Linus H W Van Der PlasAbstract:A highly synchronized in vitro tuberization system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of Hexose Phosphates and related products during stolon-to-tuber transition of potato (Solanum tuberosum L.). At tuberization the activity of enzymes involved in glycolysis and the oxidative pentose Phosphate pathway (OPPP) showed a small but clear increase. This increase reflects a higher capacity of respiratory(-related) metabolism, presumably due to the onset of rapid cell division in the apical part of the tuberizing stolon. During the phase of successive tuber growth these enzymes decreased in activity, suggesting that the concomitant massive starch accumulation is not accompanied by a large increase in respiration. A high degree of positive correlation between the activities of these enzymes could be observed, implying that the level of respiratory metabolism-related enzymes is co-ordinately regulated by the same mechanism of coarse control. The activity pattern of pyroPhosphate:fructose-6-Phosphate phosphotransferase (PFP) showed no developmental change and does not resemble the activity pattern of the enzymes participating in respiratory(-related) metabolism. Instead, its level of activity is very likely the result of metabolic regulation. The level of the content of the metabolites UDP-glucose (UDPGlc) and glucose-6-Phosphate (Glc6P) decreased after the onset of tuberization. This decline indicates that tuber induction is not accompanied by an appreciable increase in the level of the cytosolic Hexose Phosphate (Hexose-P) content but that it rather remains on a low level, which might be a prerequisite in order to maintain a high net rate of sucrose degradation during tuber development. In contrast to UDPGlc and Glc6P, the content of fructose-1,6-bisPhosphate (Fru1,6bisP) showed an increase after tuber induction. The overall activities of ADP-glucose pyrophosphorylase (AGPase) and starch phosphorylase (STP) both showed a large increase after tuber initiation, which is consistent with their presumed role in the process of starch synthesis and accumulation during rapid tuber growth.
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Developmental changes of enzymes involved in conversion of sucrose to Hexose-Phosphate during early tuberisation of potato.
Planta, 1997Co-Authors: N.j.g. Appeldoorn, Dick Vreugdenhil, Richard G F Visser, S.m. De Bruijn, E.a.m. Koot-gronsveld, L H W Van Der PlasAbstract:A highly synchronised in-vitro tuberisation system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of sucrose to Hexose-Phosphates during stolon-to-tuber transition of potato (Solanum tuberosum L.). Two different non-tuberising systems were included to distinguish between changes that are or are not tuber-specific. At tuberisation the activity of soluble acid invertase decreased (13-fold) and of sucrose synthase increased (12-fold). The activity of both enzymes remained unchanged in the non-tuberising treatments. Based on the opposite patterns and large difference in activity of these two sucrolytic enzymes, we conclude that sucrose synthase constitutes the predominant route of sucrose breakdown after tuber initiation. During the period before tuberisation, the activity of cell-wall-bound invertase and of hexokinase showed a highly positive correlation (r 2 = 0.96 in all the three treatments, suggesting coordinated coarse control of both enzyme activities. After the onset of tuberisation cell-wall-bound invertase activity decreased to a very low level, a change not observed in the non-tuberising systems, indicating that cell-wall-bound invertase is presumably not involved in the unloading mechanism and/or short-distance transport of sucrose within the perimedulla of growing tubers. The overall activity of fructokinase and of hexokinase both showed a fourfold increase after tuber initiation, but remained unchanged in the non-tuberising systems. The increase of fructokinase suggests that the phosphorylation of fructose by fructokinase down-regulates the cytosolic fructose content in order to maintain a high sucrose-synthase-catalysed net flux of sucrose to phosphorylated Hexoses during rapid tuber growth. The increase of total glucose-phosphorylating potential could be a response to the tuberisation-related starch accumulation process. The activity of UDP-glucose pyrophosphorylase showed no developmental change. The level of UDP-glucose pyrophosphorylase activity is very likely the result of metabolic regulation.