A study of the relationship between seed dormancy and pentose phosphate pathway activity in Avena fatua

1983 ◽  
Vol 61 (3) ◽  
pp. 667-670 ◽  
Author(s):  
E. P. Fuerst ◽  
M. K. Upadhyaya ◽  
G. M. Simpson ◽  
J. M. Naylor ◽  
S. W. Adkins
Keyword(s):  
Seed Dormancy ◽  
Pentose Phosphate Pathway ◽  
Krebs Cycle ◽  
Pure Line ◽  
Pentose Phosphate ◽  
Avena Fatua ◽  
Wild Oats ◽  
Gibberellin Treatment ◽  
The Relationship ◽  
Increased Activity

The hypothesis that loss of seed dormancy is associated with an increased activity of the pentose phosphate pathway (PPP) relative to glycolysis and the Krebs cycle was tested. The PPP activity was monitored by measuring the C6/C1 ratio in embryos excised from incubated caryopses of two genetically pure nondormant (ND) lines and in three dormant (D) lines of Avena fatua L., the wild oat. The C6/C1 ratios of all lines were similar at the commencement of incubation. In the two ND lines the ratio increased steadily prior to and during emergence of the radicle. In the three D lines the ratio increased during the first 24 h and then remained almost constant; there was no germination. When gibberellin treatment was used to overcome dormancy in the D lines, the C6/C1 ratio increased during the first 24 h in two of the lines and continued to increase parallel to germination in a manner similar to normal germination in ND lines. In the third D line, despite loss of dormancy from gibberellin treatment, the ratio did not increase after 24 h. Loss of dormancy during dry storage of seeds of a D-type pure line was accompanied by an increase in the C6/C1 ratio, as measured in freshly imbibed seeds. This indicates a decreased activity of the PPP relative to glycolysis and the Krebs cycle. These findings are contrary to Roberts's hypothesis that loss of dormancy in wild oats is associated with a relative decrease in the C6/C1 ratio.

The effects of acetate and of pyruvate on the pathways of glucose catabolism in lactating mammary tissue. II. Sheep tissue

1969 ◽  
Vol 36 (3) ◽  
pp. 469-478 ◽  
Author(s):  
R. W. Smith ◽  
R. F. Glascock
Keyword(s):  
Pentose Phosphate Pathway ◽  
Acid Synthesis ◽  
Pentose Phosphate ◽  
Mammary Tissue ◽  
Glucose Catabolism ◽  
Glucose Carbon ◽  
Rat Tissue ◽  
The Relationship ◽  
Stimulation Of

SummaryA study was made of the changes in the rates of oxidation of the C(1), C(2) and C(6) atoms of glucose and in the pathways of glucose catabolism in sheep udder tissue in vitro which occurred when acetate and pyruvate were added.Whereas in rat mammary tissue the rate of oxidation of the C(1) atom of glucose was very much greater than that of the C(6) atom, the ratio of the rates of oxidation of these 2 atoms in sheep tissue was less than 2 when glucose was the only substrate.The addition of acetate resulted in an unequal stimulation of the oxidation of these 2 atoms, with the result that the ratio of their rates of oxidation was about doubled. The rate of oxidation of the C(2) atom was also increased.Acetate also increased the participation of the pentose phosphate pathway in glucose catabolism as measured by the incorporation of the C(1) and C(6) atoms of glucose into fatty acids, lactic acid and glycerol.Pyruvate produced little effect on the rate of oxidation of the C(1) atom but somewhat depressed that of the C(6) atom of glucose. At the same time, it caused a large increase in the participation of the pentose phosphate pathway.These results are discussed with reference to re-cycling of glucose carbon in the pentose phosphate pathway and to the relationship between that pathway and fatty acid synthesis. It is noted that the incorporation of glucose carbon into the 3 intermediates used gave values for the participation of that pathway which were in better agreement than was obtained in rat tissue. It is concluded that triose phosphates are more nearly in equilibrium in sheep than in rat mammary tissue.

scholarly journals YvcK of Bacillus subtilis is required for a normal cell shape and for growth on Krebs cycle intermediates and substrates of the pentose phosphate pathway

Microbiology ◽  
2005 ◽  
Vol 151 (11) ◽  
pp. 3777-3791 ◽  
Author(s):  
Boris Görke ◽  
Elodie Foulquier ◽  
Anne Galinier
Keyword(s):  
Bacillus Subtilis ◽  
Pentose Phosphate Pathway ◽  
Carbon Metabolism ◽  
Carbon Sources ◽  
Krebs Cycle ◽  
Normal Growth ◽  
Central Carbon Metabolism ◽  
Pentose Phosphate ◽  
Homologous Protein ◽  
Krebs Cycle Intermediates

The HPr-like protein Crh has so far been detected only in the bacillus group of bacteria. In Bacillus subtilis, its gene is part of an operon composed of six ORFs, three of which exhibit strong similarity to genes of unknown function present in many bacteria. The promoter of the operon was determined and found to be constitutively active. A deletion analysis revealed that gene yvcK, encoded by this operon, is essential for growth on Krebs cycle intermediates and on carbon sources metabolized via the pentose phosphate pathway. In addition, cells lacking YvcK acquired media-dependent filamentous or L-shape-like aberrant morphologies. The presence of high magnesium concentrations restored normal growth and cell morphology. Furthermore, suppressor mutants cured from these growth defects appeared spontaneously with a high frequency. Such suppressing mutations were identified in a transposon mutagenesis screen and found to reside in seven different loci. Two of them mapped in genes of central carbon metabolism, including zwf, which encodes glucose-6-phosphate dehydrogenase and cggR, the product of which regulates the synthesis of glyceraldehyde-3-phosphate dehydrogenase. All these results suggest that YvcK has an important role in carbon metabolism, probably in gluconeogenesis required for the synthesis of cell wall precursor molecules. Interestingly, the Escherichia coli homologous protein, YbhK, can substitute for YvcK in B. subtilis, suggesting that the two proteins have been functionally conserved in these different bacteria.

Genetic adaptation for seed dormancy in Avena fatua

1976 ◽  
Vol 54 (3-4) ◽  
pp. 306-312 ◽  
Author(s):  
J. M. Naylor ◽  
S. Jana
Keyword(s):  
Genetic Variability ◽  
Seed Dormancy ◽  
Natural Populations ◽  
Avena Fatua ◽  
Genetic Adaptation ◽  
Agronomic Practices ◽  
Primary Dormancy ◽  
Local Populations ◽  
Wild Oats

Genetic variability affecting duration of primary dormancy is demonstrated in natural populations of wild oats. Marked differences were found among local populations in germination behavior. The evidence suggests that these differences result in part from genetic adaptation to agronomic practices.

scholarly journals Transcriptional and Metabolic Responses of Bacillus subtilis to the Availability of Organic Acids: Transcription Regulation Is Important but Not Sufficient To Account for Metabolic Adaptation

2006 ◽  
Vol 73 (2) ◽  
pp. 499-507 ◽  
Author(s):  
Oliver Schilling ◽  
Oliver Frick ◽  
Christina Herzberg ◽  
Armin Ehrenreich ◽  
Elmar Heinzle ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Organic Acids ◽  
Pentose Phosphate Pathway ◽  
Metabolic Regulation ◽  
Metabolic Flux ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Metabolic Adaptation ◽  
Acetyl Coa ◽  
Additional Level

ABSTRACT The soil bacterium Bacillus subtilis can use sugars or organic acids as sources of carbon and energy. These nutrients are metabolized by glycolysis, the pentose phosphate pathway, and the Krebs citric acid cycle. While the response of B. subtilis to the availability of sugars is well understood, much less is known about the changes in metabolism if organic acids feeding into the Krebs cycle are provided. If B. subtilis is supplied with succinate and glutamate in addition to glucose, the cells readjust their metabolism as determined by transcriptome and metabolic flux analyses. The portion of glucose-6-phosphate that feeds into the pentose phosphate pathway is significantly increased in the presence of organic acids. Similarly, important changes were detected at the level of pyruvate and acetyl coenzyme A (acetyl-CoA). In the presence of organic acids, oxaloacetate formation is strongly reduced, whereas the formation of lactate is significantly increased. The alsSD operon required for acetoin formation is strongly induced in the presence of organic acids; however, no acetoin formation was observed. The recently discovered phosphorylation of acetolactate decarboxylase may provide an additional level of control of metabolism. In the presence of organic acids, both types of analyses suggest that acetyl-CoA was catabolized to acetate rather than used for feeding the Krebs cycle. Our results suggest that future work has to concentrate on the posttranslational mechanisms of metabolic regulation.

The effect of sodium hypochlorite and gibberellic acid on seed dormancy and germination of wild oats (Avena fatua)

1979 ◽  
Vol 57 (16) ◽  
pp. 1729-1734 ◽  
Author(s):  
A. I. Hsiao
Keyword(s):  
Gibberellic Acid ◽  
Seed Dormancy ◽  
Sodium Hypochlorite ◽  
Slow Rate ◽  
Avena Fatua ◽  
Germination Inhibitors ◽  
Wild Oats ◽  
Dormancy Induction ◽  
Seed Dormancy And Germination

The seed coverings, including the pericarp and testa of the caryopsis and the hull, arc the main barriers to the exchange of gases and the penetration of exogenous gibberellic acid (GA3) for germination of wild oats (Avena fatua L.). Dormancy was induced in seeds by immersing them in water for 15 minor longer. Dormancy induction was greater in those seeds immersed for up to 1 h in 6% sodium hypochlorite (NaOCl) and then 1 h in water than in those seeds immersed only in water for 1 h. The addition of GA3, to seeds subjected to NaOCl treatment for 15 min or less did not break dormancy, indicating a slow rate of entry, or the exclusion, of GA3, by the seeds. In the presence of GA3, germination increased with increasing exposure to NaOCl. Maximum germination was obtained by immersing dry seeds in NaOCl for 2 h, in water for 1 h, and then incubating the seeds in GA3. Gibberellic acid was not required for complete germination of imbibed, dehulled seeds immersed in NaOCl for 1 h then in water for 1 h, but it was necessary to use 10−4 M GA3 for complete germination of intact seeds that were treated with NaOCl or 2 h then with water for 1 h. Imbibed, dormant seeds that were dehulled and pierced required 10−7 M GA3, to give complete germination in this study. Piercing of the seed coverings enhances GA3, penetration and thus increases the availability of GA3, for germination. NaOCl treatment to the seeds mimics the effects of piercing. NaOCl may also have caused loss of germination inhibitors or rendered these inhibitors susceptible to oxidation. However, prolonged NaOCl treatment resulted in either poor germination or seed disintegration.

Dormancy studies in seed of Avena fatua. 13. Influence of drought stress during seed development on duration of seed dormancy

1982 ◽  
Vol 60 (6) ◽  
pp. 1016-1020 ◽  
Author(s):  
Ramma Sawhney ◽  
J. M. Naylor
Keyword(s):  
High Temperature ◽  
Water Stress ◽  
Drought Stress ◽  
Seed Development ◽  
Seed Dormancy ◽  
Pure Line ◽  
Avena Fatua ◽  
Primary Dormancy ◽  
Pure Lines

Plants of genetically dormant (D) and nondormant (ND) pure lines of Avena fatua were exposed to water stress during seed development. In comparison with normally well-watered controls, seeds produced by water-stressed plants exhibited shorter duration of primary dormancy. The magnitude of the effect varied among D families, but was consistently greater than in ND families.It is concluded that the dormancy phenotype of D lines is highly plastic and that the responses to high temperature and water stress are similar in a given pure line.

Coadaptation of seed dormancy and hormonal dependence of α-amylase production in endosperm segments of Avena fatua

1982 ◽  
Vol 60 (7) ◽  
pp. 1142-1147 ◽  
Author(s):  
Mahesh K. Upadhyaya ◽  
James M. Naylor ◽  
Graham M. Simpson
Keyword(s):  
Seed Dormancy ◽  
Reducing Sugars ◽  
Avena Fatua ◽  
Multiple Alleles ◽  
Wild Oats ◽  
Amylase Production ◽  
Hormonal Dependence ◽  
Oat Seeds ◽  
Pure Lines

Autonomous (independent of the germinating embryo) α-amylase production was compared in the endosperm segments of some genetically pure lines of Avena fatua L. (wild oats) differing in the duration of their seed dormancy. Endosperm segments from six randomly taken dormant lines showed no α-amylase production unless gibberellic acid (GA3) was supplied. In contrast, endosperm segments from four out of six nondormant lines produced and released substantial amounts of α -amylase and reducing sugars. Thus, natural selection has resulted in coadaptation of seed dormancy and a rigorous dependence of endosperm hydrolysis on gibberellins produced by the germinating embryo. The variability in the degree of autonomy amongst nondormant lines indicates that the observed coupling of these two traits in dormant lines is not due to simple pleiotropy, but probably reflects the action of multiple genetic loci or multiple alleles. These results also indicate that long-term endosperm stability confers little advantage in wild oat seeds predisposed to brief periods of residence in soil.

Effects of insulin, glucocorticoids and thyroid hormones on the activities of key enzymes of glycolysis, glutaminolysis, the pentose-phosphate pathway and the Krebs cycle in rat macrophages

1992 ◽  
Vol 135 (2) ◽  
pp. 213-219 ◽  
Author(s):  
L. F. B. P. Costa Rosa ◽  
Y. Cury ◽  
R. Curi
Keyword(s):  
Thyroid Hormones ◽  
Pentose Phosphate Pathway ◽  
Culture Medium ◽  
Citrate Synthase ◽  
Inflammatory Responses ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Macrophage Phagocytosis ◽  
And Function ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT In the present study the effects of insulin, glucocorticoids and thyroid hormones on macrophage metabolism and function were investigated. The maximum activities of hexokinase, glucose-6-phosphate dehydrogenase, glutaminase and citrate synthase were determined in macrophages obtained from hormonetreated rats and those cultured for a period of 48 h in the presence of hormones. Macrophage phagocytosis was markedly inhibited by dexamethasone and thyroid hormones, remaining unchanged when insulin was added to the culture medium, however. The changes in the enzyme activities caused by hormone treatments of the rats were very similar to those found in culture. Insulin enhanced citrate synthase and hexokinase activities and diminished those of glutaminase and glucose-6-phosphate dehydrogenase. Dexamethasone had a similar effect except on glucose6-phosphate dehydrogenase. The addition of thyroid hormones to the culture medium raised the activities of glutaminase and hexokinase and reduced that of citrate synthase. The results presented support the suggestion that the effects of insulin, glucocorticoids and thyroid hormones on immune and inflammatory responses could well be mediated through changes in macrophage metabolism.. Journal of Endocrinology (1992) 135, 213–219

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