Abstract
The activity of nitrate reductase (NR) in needles of red spruce (Picea rubens Sarg.) trees is normally very low: 220 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in 1-year-old nursery-grown seedlings and 47 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in plants excavated from a high-elevation spruce forest. The assimilation of nitrogen oxide pollutants absorbed from the atmosphere by red spruce trees may, therefore, require that NR is induced in the needles. To test for induction of NR, 1-year-old, nursery-grown red spruce seedlings were exposed to NO{sub 2}, HNO{sub 3} vapor, or acid mist containing nitrate, and the activity of NR in needles was measured using an in vivo assay. One day after exposure to NO{sub 2} (75 nl{center dot}l{sup {minus}1}) began, NR activity had increased to 765 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1}, more than 3 times that of unexposed control plants. During the 7-day exposure, NR activity of the treated seedlings declined 36%, but it remained significantly higher than that of controls. One day after exposure ended, NR activity returned to the control level. Forest-frown seedlings exhibited a similar response to NO{sub 2}, but at a much lower level. Nitric acid vapor (75 nl{center dot}l{sup {minus}1}) also induced NR in red spruce needles,more » and the pattern and magnitude of response were similar to that with NO{sub 2}, except that the NR activity did not return to control levels until 2 days after exposure ended. Exposure of seedlings to simulated acid mist containing nitrate (pH 3.5 and pH 5.0) did not result in a significant change in NR activity. These results indicate that red spruce is capable of assimilating NO{sub 2} and HNO{sub 3} vapor, and that hypotheses of forest decline based on foliar assimilation of pollutant nitrogen oxides are tenable.« less
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Claims 9
Claim · model-written summary
Nitrate reductase activity was 220 in nursery seedlings and 47 in excavated forest plants.
- Taxon
- red spruce
Picea rubense0 - Organ / stage
- needlese0
- Gene
- nitrate reductasee0
- Outcome
- activity of nitrate reductase (NR)e0
- Value
- 220 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1}e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“activity of nitrate reductase (NR) in needles of red spruce (Picea rubens Sarg.) trees is normally very low: 220 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in 1-year-old nursery-grown seedlings and 47 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in plants excavated from a high-elevation spruce forest”
Claim · model-written summary
NO2 exposure increased nitrate reductase activity to 765 after one day, over three times controls.
- Taxon
- red sprucePicea rubense1
- Treatment
- NO{sub 2} (75 nl{center dot}l{sup {minus}1})e0
- Gene
- NRe0
- Outcome
- NR activitye0
- Direction
- increasede0
- Value
- 765 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1}e0
- Comparator
- unexposed control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“One day after exposure to NO{sub 2} (75 nl{center dot}l{sup {minus}1}) began, NR activity had increased to 765 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1}, more than 3 times that of unexposed control plants”
e1“red spruce seedlings”
Claim · model-written summary
During seven days of exposure, treated seedling NR activity declined 36% but stayed significantly above controls.
- Taxon
- red sprucePicea rubense1
- Treatment
- NO{sub 2}e2
- Outcome
- NR activitye0
- Direction
- declinede0
- Value
- 36%e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the 7-day exposure, NR activity of the treated seedlings declined 36%, but it remained significantly higher than that of controls”
e1“red spruce seedlings”
e2“exposed to NO{sub 2}”
Claim · model-written summary
NR activity returned to control level one day after NO2 exposure ended.
- Taxon
- red sprucePicea rubense1
- Outcome
- NR activitye0
- Direction
- returned to the control levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“One day after exposure ended, NR activity returned to the control level”
e1“red spruce seedlings”
Claim · model-written summary
Forest-grown seedlings responded similarly to NO2, at a lower level.
- Taxon
- red sprucePicea rubense1
- Outcome
- response to NO{sub 2}e0
- Direction
- much lowere0
- Setting
- Forest-frowne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Forest-frown seedlings exhibited a similar response to NO{sub 2}, but at a much lower level”
e1“red spruce seedlings”
Claim · model-written summary
Nitric acid vapor induced needle NR with a similar magnitude and pattern to NO2.
- Taxon
- red sprucePicea rubense0
- Treatment
- Nitric acid vapor (75 nl{center dot}l{sup {minus}1})e0
- Outcome
- NRe0
- Direction
- inducede0
- Comparator
- NO{sub 2}e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitric acid vapor (75 nl{center dot}l{sup {minus}1}) also induced NR in red spruce needles,more » and the pattern and magnitude of response were similar to that with NO{sub 2}”
Claim · model-written summary
After nitric acid vapor, NR activity returned to control levels two days after exposure ended.
- Taxon
- red sprucePicea rubense1
- Outcome
- NR activitye0
- Value
- 2 dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NR activity did not return to control levels until 2 days after exposure ended”
e1“red spruce needles”
Claim · model-written summary
Acid mist containing nitrate did not significantly change NR activity.
- Taxon
- red sprucePicea rubense1
- Treatment
- simulated acid mist containing nitrate (pH 3.5 and pH 5.0)e0
- Outcome
- NR activitye0
- Direction
- did not result in a significant changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure of seedlings to simulated acid mist containing nitrate (pH 3.5 and pH 5.0) did not result in a significant change in NR activity”
e1“red spruce seedlings”
Claim · model-written summary
The results indicate that red spruce can assimilate NO2 and HNO3 vapor.
- Taxon
- red sprucePicea rubense0
- Outcome
- assimilating NO{sub 2} and HNO{sub 3} vapore0
- Qualifier
- assimilatinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“red spruce is capable of assimilating NO{sub 2} and HNO{sub 3} vapor”
The same questions in other papers
nitric acid · physiology: enzyme activity · Picea rubens (red spruce)Results agree
1 paper in the same direction as this paper
- positive
nitrogen · physiology: enzyme activity · Picea rubens (red spruce)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- no effect
ph · physiology: enzyme activity · Picea rubens (red spruce)Results agree
1 paper in the same direction as this paper
- no effect
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.