Abstract
The starch synthase activity of bundle sheath cells of maize leaves is very low in darkened plants and increases on illumination. In order to find an explanation of these facts we subjected leaf strips, isolated bundle sheath cells and enzymic preparations to pH-changes and to oxidizing or reducing substances. We found that the increase of the activity produced by light could also be caused in the leaf strips by adding malate to the suspending fluid in the dark. On the contrary, with isolated bundle sheath cells no increase with light or with the addition of malate could be observed. There was a decrease of activity due to acidification or to the addition of dichlorophenol-indophenol (DCPIP). The same effect could be observed with enzymic preparations as with the isolated bundle sheath cells, whereas the decrease of activity was higher by acidification of samples coming from darkened plants than for those enzymes prepared from illuminated plants. Also other substances inhibited the synthase activity: benzoquinone, DOPA, caffeic acid, TMPD or Fe (CN6) 3- and PCMB, while only DTE could increase it. After preincubation with PCMB the enzyme activity could be restored with DTE, not so for the preincubation with DCPIP. With an enzymic preparation that contained intact organelles the increase of activity could also be produced by NADH. Thus we follow that the decrease of synthase activity in the darkened plants is due to acidification and to the presence of oxidizing substances, too.
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Claims 14
Claim · model-written summary
Starch synthase activity is low in darkened plants and rises with illumination.
- Organ / stage
- bundle sheath cells of maize leavese0
- Gene
- starch synthasee0
- Outcome
- starch synthase activitye0
- Direction
- increasese0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“starch synthase activity of bundle sheath cells of maize leaves is very low in darkened plants and increases on illumination”
Claim · model-written summary
Malate in darkness increased starch synthase activity in leaf strips.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increase of the activity produced by light could also be caused in the leaf strips by adding malate to the suspending fluid in the dark”
t0“maize leaves”
Claim · model-written summary
Light did not increase activity in isolated bundle sheath cells.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with isolated bundle sheath cells no increase with light or with the addition of malate could be observed”
t0“maize leaves”
Claim · model-written summary
Malate did not increase activity in isolated bundle sheath cells.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with isolated bundle sheath cells no increase with light or with the addition of malate could be observed”
t0“maize leaves”
Claim · model-written summary
Acidification reduced starch synthase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a decrease of activity due to acidification”
t0“maize leaves”
Claim · model-written summary
DCPIP reduced starch synthase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a decrease of activity due to acidification or to the addition of dichlorophenol-indophenol (DCPIP)”
t0“maize leaves”
Claim · model-written summary
Acidification caused a larger activity decrease in enzymes from darkened than illuminated plants.
- Treatment
- acidificatione0
- Outcome
- decrease of activitye0
- Direction
- highere0
- Comparator
- enzymes prepared from illuminated plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decrease of activity was higher by acidification of samples coming from darkened plants than for those enzymes prepared from illuminated plants”
t0“maize leaves”
Claim · model-written summary
Benzoquinone, DOPA and caffeic acid inhibited synthase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“benzoquinone, DOPA, caffeic acid, TMPD or Fe (CN6) 3- and PCMB, while only DTE could increase it”
e1“Also other substances inhibited the synthase activity”
t0“maize leaves”
Claim · model-written summary
TMPD, Fe (CN6) 3- and PCMB inhibited synthase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“benzoquinone, DOPA, caffeic acid, TMPD or Fe (CN6) 3- and PCMB, while only DTE could increase it”
e1“Also other substances inhibited the synthase activity”
t0“maize leaves”
Claim · model-written summary
DTE increased synthase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“only DTE could increase it”
e1“inhibited the synthase activity”
t0“maize leaves”
Claim · model-written summary
DTE restored activity after PCMB pretreatment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After preincubation with PCMB the enzyme activity could be restored with DTE”
t0“maize leaves”
Claim · model-written summary
DTE did not restore activity after DCPIP pretreatment.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“not so for the preincubation with DCPIP”
e1“enzyme activity could be restored with DTE”
t0“maize leaves”
Claim · model-written summary
NADH increased activity in an enzyme preparation containing intact organelles.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With an enzymic preparation that contained intact organelles the increase of activity could also be produced by NADH”
t0“maize leaves”
Claim · model-written summary
The authors attribute low dark-period synthase activity to acidification and oxidizing substances.
- Outcome
- decrease of synthase activitye0
- Qualifier
- acidification and to the presence of oxidizing substancese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decrease of synthase activity in the darkened plants is due to acidification and to the presence of oxidizing substances, too”
t0“maize leaves”
The same questions in other papers
iron atom · physiology: enzyme activity · Zea mays (maize)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- negative
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.