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James B Mcclintock - One of the best experts on this subject based on the ideXlab platform.
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the effects of chronic Inorganic and organic Phosphate exposure on bactericidal activity of the coelomic fluid of the sea urchin lytechinus variegatus lamarck echinodermata echinoidea
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2009Co-Authors: Anne S Bottger, James B McclintockAbstract:Abstract The sea urchin Lytechinus variegatus can survive chronic exposure to sodium Phosphate (Inorganic Phosphate) concentrations as high as 3.2 mg L− 1, and triethyl Phosphate (organic Phosphate) concentrations of 1000 mg L− 1. However, chronic exposure to low (0.8 mg L− 1 Inorganic and 10 mg L− 1 organic Phosphate), medium (1.6 mg L− 1 Inorganic and 100 mg L− 1 organic Phosphate) or high (3.2 mg L− 1 Inorganic and 1000 mg L− 1 organic Phosphate) sublethal concentrations of these Phosphates inhibit bactericidal clearance of the marine bacterium Vibrio sp. Bacteria were exposed to coelomic fluid collected from individuals maintained in either artificial seawater, or three concentrations of either Inorganic Phosphate or organic Phosphate. Sterile marine broth, natural seawater and cell free coelomic fluid (cfCF) were employed as controls. Bacterial survival indices were measured at 0, 24 and 48 h periods once a week for four weeks. Bacteria were readily eliminated from the whole coelomic fluid (wCF) of individuals maintained in artificial seawater. Individuals maintained in Inorganic Phosphates were able to clear bacteria following a two week exposure period, while individuals maintained at even low concentrations of organic Phosphates failed to clear all bacteria from their coelomic fluid. Exposure to Phosphates represses antimicrobial defenses and may ultimately compromise survival of L. variegatus in the nearshore environment.
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effects of Inorganic and organic Phosphates on feeding feeding absorption nutrient allocation growth and righting responses of the sea urchin lytechinus variegatus
Marine Biology, 2001Co-Authors: S A Bottger, James B Mcclintock, Thomas S KlingerAbstract:The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium Phosphate (Inorganic Phosphate) concentrations as high as 3.2 mg l−1, and triethyl Phosphate (organic Phosphate) concentrations of 1,000 mg l−1. However, chronic exposure to low (0.8 mg l−1 Inorganic and 10 mg l−1 organic Phosphate), medium (1.6 mg l−1 Inorganic and 100 mg l−1 organic Phosphate) or high (3.2 mg l−1 Inorganic and 1,000 mg l−1 organic Phosphate) sublethal concentrations of these Phosphates inhibits feeding, fecal production, nutrient absorption and allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed to medium and high concentrations of Inorganic Phosphates and all levels of organic Phosphates. Feeding absorption efficiencies for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic Phosphate. Feeding absorption efficiencies for lipids were significantly reduced in the highest Inorganic Phosphate concentration only, while they decreased significantly for protein with increasing Phosphate exposure. Carbohydrate and lipid levels in gonad and gut tissues decreased significantly with exposure to increasing Phosphate concentrations, potentially impairing both gametogenesis and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations of either Phosphate. Growth rates decreased significantly under the influence of all Phosphate concentrations, while increasing in seawater alone. Individuals exposed to increasing Phosphate concentrations showed reduced righting responses (a measure of stress) and no acclimation in righting times during chronic exposure to Phosphates over a 4 week period. These findings indicate that shallow-water populations of L. variegatus subjected to Inorganic and organic Phosphate pollutants will exhibit stress and be inhibited in their growth and performance due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues.
Peter Geigenberger - One of the best experts on this subject based on the ideXlab platform.
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starch synthesis in potato tubers is regulated by post translational redox modification of adp glucose pyrophosphorylase a novel regulatory mechanism linking starch synthesis to the sucrose supply
The Plant Cell, 2002Co-Authors: Axel Tiessen, Janneke H M Hendriks, Mark Stitt, Anja Branscheid, Yves Gibon, Eva M Farre, Peter GeigenbergerAbstract:Transcriptional and allosteric regulation of ADP-Glc pyrophosphorylase (AGPase) plays a major role in the regulation of starch synthesis. Analysis of the response after detachment of growing potato tubers from the mother plant revealed that this concept requires extension. Starch synthesis was inhibited within 24 h of tuber detachment, even though the catalytic subunit of AGPase (AGPB) and overall AGPase activity remained high, the substrates ATP and Glc-1-P increased, and the glycerate-3-Phosphate/Inorganic orthoPhosphate (the allosteric activator and inhibitor, respectively) ratio increased. This inhibition was abolished in transformants in which a bacterial AGPase replaced the potato AGPase. Measurements of the subcellular levels of each metabolite between Suc and starch established AGPase as the only step whose substrates increase and mass action ratio decreases after detachment of wild-type tubers. Separation of extracts on nonreducing SDS gels revealed that AGPB is present as a mixture of monomers and dimers in growing tubers and becomes dimerized completely in detached tubers. Dimerization led to inactivation of the enzyme as a result of a marked decrease of the substrate affinity and sensitivity to allosteric effectors. Dimerization could be reversed and AGPase reactivated in vitro by incubating extracts with DTT. Incubation of tuber slices with DTT or high Suc levels reduced dimerization, increased AGPase activation, and stimulated starch synthesis in vivo. In intact tubers, the Suc content correlated strongly with AGPase activation across a range of treatments, including tuber detachment, aging of the mother plant, heterologous overexpression of Suc phosphorylase, and antisense inhibition of endogenous AGPase activity. Furthermore, activation of AGPase resulted in a stimulation of starch synthesis and decreased levels of glycolytic intermediates.
Thomas S Klinger - One of the best experts on this subject based on the ideXlab platform.
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effects of Inorganic and organic Phosphates on feeding feeding absorption nutrient allocation growth and righting responses of the sea urchin lytechinus variegatus
Marine Biology, 2001Co-Authors: S A Bottger, James B Mcclintock, Thomas S KlingerAbstract:The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium Phosphate (Inorganic Phosphate) concentrations as high as 3.2 mg l−1, and triethyl Phosphate (organic Phosphate) concentrations of 1,000 mg l−1. However, chronic exposure to low (0.8 mg l−1 Inorganic and 10 mg l−1 organic Phosphate), medium (1.6 mg l−1 Inorganic and 100 mg l−1 organic Phosphate) or high (3.2 mg l−1 Inorganic and 1,000 mg l−1 organic Phosphate) sublethal concentrations of these Phosphates inhibits feeding, fecal production, nutrient absorption and allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed to medium and high concentrations of Inorganic Phosphates and all levels of organic Phosphates. Feeding absorption efficiencies for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic Phosphate. Feeding absorption efficiencies for lipids were significantly reduced in the highest Inorganic Phosphate concentration only, while they decreased significantly for protein with increasing Phosphate exposure. Carbohydrate and lipid levels in gonad and gut tissues decreased significantly with exposure to increasing Phosphate concentrations, potentially impairing both gametogenesis and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations of either Phosphate. Growth rates decreased significantly under the influence of all Phosphate concentrations, while increasing in seawater alone. Individuals exposed to increasing Phosphate concentrations showed reduced righting responses (a measure of stress) and no acclimation in righting times during chronic exposure to Phosphates over a 4 week period. These findings indicate that shallow-water populations of L. variegatus subjected to Inorganic and organic Phosphate pollutants will exhibit stress and be inhibited in their growth and performance due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues.
Axel Tiessen - One of the best experts on this subject based on the ideXlab platform.
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starch synthesis in potato tubers is regulated by post translational redox modification of adp glucose pyrophosphorylase a novel regulatory mechanism linking starch synthesis to the sucrose supply
The Plant Cell, 2002Co-Authors: Axel Tiessen, Janneke H M Hendriks, Mark Stitt, Anja Branscheid, Yves Gibon, Eva M Farre, Peter GeigenbergerAbstract:Transcriptional and allosteric regulation of ADP-Glc pyrophosphorylase (AGPase) plays a major role in the regulation of starch synthesis. Analysis of the response after detachment of growing potato tubers from the mother plant revealed that this concept requires extension. Starch synthesis was inhibited within 24 h of tuber detachment, even though the catalytic subunit of AGPase (AGPB) and overall AGPase activity remained high, the substrates ATP and Glc-1-P increased, and the glycerate-3-Phosphate/Inorganic orthoPhosphate (the allosteric activator and inhibitor, respectively) ratio increased. This inhibition was abolished in transformants in which a bacterial AGPase replaced the potato AGPase. Measurements of the subcellular levels of each metabolite between Suc and starch established AGPase as the only step whose substrates increase and mass action ratio decreases after detachment of wild-type tubers. Separation of extracts on nonreducing SDS gels revealed that AGPB is present as a mixture of monomers and dimers in growing tubers and becomes dimerized completely in detached tubers. Dimerization led to inactivation of the enzyme as a result of a marked decrease of the substrate affinity and sensitivity to allosteric effectors. Dimerization could be reversed and AGPase reactivated in vitro by incubating extracts with DTT. Incubation of tuber slices with DTT or high Suc levels reduced dimerization, increased AGPase activation, and stimulated starch synthesis in vivo. In intact tubers, the Suc content correlated strongly with AGPase activation across a range of treatments, including tuber detachment, aging of the mother plant, heterologous overexpression of Suc phosphorylase, and antisense inhibition of endogenous AGPase activity. Furthermore, activation of AGPase resulted in a stimulation of starch synthesis and decreased levels of glycolytic intermediates.
Anne S Bottger - One of the best experts on this subject based on the ideXlab platform.
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the effects of chronic Inorganic and organic Phosphate exposure on bactericidal activity of the coelomic fluid of the sea urchin lytechinus variegatus lamarck echinodermata echinoidea
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2009Co-Authors: Anne S Bottger, James B McclintockAbstract:Abstract The sea urchin Lytechinus variegatus can survive chronic exposure to sodium Phosphate (Inorganic Phosphate) concentrations as high as 3.2 mg L− 1, and triethyl Phosphate (organic Phosphate) concentrations of 1000 mg L− 1. However, chronic exposure to low (0.8 mg L− 1 Inorganic and 10 mg L− 1 organic Phosphate), medium (1.6 mg L− 1 Inorganic and 100 mg L− 1 organic Phosphate) or high (3.2 mg L− 1 Inorganic and 1000 mg L− 1 organic Phosphate) sublethal concentrations of these Phosphates inhibit bactericidal clearance of the marine bacterium Vibrio sp. Bacteria were exposed to coelomic fluid collected from individuals maintained in either artificial seawater, or three concentrations of either Inorganic Phosphate or organic Phosphate. Sterile marine broth, natural seawater and cell free coelomic fluid (cfCF) were employed as controls. Bacterial survival indices were measured at 0, 24 and 48 h periods once a week for four weeks. Bacteria were readily eliminated from the whole coelomic fluid (wCF) of individuals maintained in artificial seawater. Individuals maintained in Inorganic Phosphates were able to clear bacteria following a two week exposure period, while individuals maintained at even low concentrations of organic Phosphates failed to clear all bacteria from their coelomic fluid. Exposure to Phosphates represses antimicrobial defenses and may ultimately compromise survival of L. variegatus in the nearshore environment.