Paul Magnano:Week 3 Individual Journal
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==Outline== | ==Outline== | ||
| + | ===Experiment=== | ||
| + | *sacchromyces cerevisiae was grown in continuous culture, with varying ammonia input concentrations, while ammonia assiilation rates remained constant | ||
| + | *ammonia is a preffered nitrogen source for s. cerevisiae, because it results in faster growth than other sources | ||
| + | *in this study, cultures were grown with same flux (relationship b/w external ammonia concentration and rte of assimilation) but different inflow ammonia concentrations | ||
| + | *Physiological parameters: | ||
| + | **S. cerevisiae SU32 grown in continuous cultures with ammonia inflow concentrations ranging from 29 to 118mM | ||
| + | **fixed glucose concentration of 100mM | ||
| + | *Fig 1A | ||
| + | **increase of ammonia concentration from 29 to 61mM resulted in increase of biomass from 4.9 to 8.2 g/liter | ||
| + | **ammonia concentration above 61mM biomass remained at 8.2 g/liter | ||
| + | **over trhe entire range of ammonia concentrations the ammonia flux into biomass was 1.1 mmol/gh | ||
| + | *Fig 1B | ||
| + | **input ammonia concentration above 44mM resulted in (c02 production/02 consumption) remained constant | ||
| + | **with ammonia limitation (ammonia input below 44mM) c02 production and 02 consumption values differed | ||
| + | **no changes in the residual glucose concentration were seen | ||
| + | **no significant changes in carbon metabolism occured when the culture was switched from ammonia excess to ammonia limitation | ||
| + | *Fig 1C | ||
| + | **ammonia within the cells reacts with ketoglutarate to produce glutamate which is converted to glutamine | ||
| + | **ketoglutarate concentration decreased from 10 to 5 umol/g when the ammonia concentration changed from limited to excess | ||
| + | **glutamate concentration increased within the cell, linearly | ||
| + | **increaing ammonia concentrations caused the concentrations of glutamate and glutamine within the cell to increase | ||
| + | |||
| + | ===Northern Analyses=== | ||
| + | *RNA analyses were done to see if RNA levels of nitrogen regulating genes changed with increased ammonia concentrations | ||
| + | *genes GDH1, GDH2,GLN1 were determined to study responses to ammonia levels | ||
| + | *Fig 2 | ||
| + | **increasing ammonia levels resulted in GDH1 levels staying the same | ||
| + | **ammonia concentrations of 29-44mM there was no GDH2, but with increase to 61mM GDH2 level increased | ||
| + | **maximum GLN1 expression was observed at 61mM | ||
| + | ** overall it was seen that ammonia concentration both repressed GDH1 and caused the expression of GDH2 | ||
==Ten New Terms== | ==Ten New Terms== | ||
Revision as of 23:10, 30 January 2013
Contents |
Outline
Experiment
- sacchromyces cerevisiae was grown in continuous culture, with varying ammonia input concentrations, while ammonia assiilation rates remained constant
- ammonia is a preffered nitrogen source for s. cerevisiae, because it results in faster growth than other sources
- in this study, cultures were grown with same flux (relationship b/w external ammonia concentration and rte of assimilation) but different inflow ammonia concentrations
- Physiological parameters:
- S. cerevisiae SU32 grown in continuous cultures with ammonia inflow concentrations ranging from 29 to 118mM
- fixed glucose concentration of 100mM
- Fig 1A
- increase of ammonia concentration from 29 to 61mM resulted in increase of biomass from 4.9 to 8.2 g/liter
- ammonia concentration above 61mM biomass remained at 8.2 g/liter
- over trhe entire range of ammonia concentrations the ammonia flux into biomass was 1.1 mmol/gh
- Fig 1B
- input ammonia concentration above 44mM resulted in (c02 production/02 consumption) remained constant
- with ammonia limitation (ammonia input below 44mM) c02 production and 02 consumption values differed
- no changes in the residual glucose concentration were seen
- no significant changes in carbon metabolism occured when the culture was switched from ammonia excess to ammonia limitation
- Fig 1C
- ammonia within the cells reacts with ketoglutarate to produce glutamate which is converted to glutamine
- ketoglutarate concentration decreased from 10 to 5 umol/g when the ammonia concentration changed from limited to excess
- glutamate concentration increased within the cell, linearly
- increaing ammonia concentrations caused the concentrations of glutamate and glutamine within the cell to increase
Northern Analyses
- RNA analyses were done to see if RNA levels of nitrogen regulating genes changed with increased ammonia concentrations
- genes GDH1, GDH2,GLN1 were determined to study responses to ammonia levels
- Fig 2
- increasing ammonia levels resulted in GDH1 levels staying the same
- ammonia concentrations of 29-44mM there was no GDH2, but with increase to 61mM GDH2 level increased
- maximum GLN1 expression was observed at 61mM
- overall it was seen that ammonia concentration both repressed GDH1 and caused the expression of GDH2
