Abstract
A cDNA corresponding to 16 kDa of the maize cyclin D2 N-terminus was cloned and this polypeptide was overexpressed to produce homologous antibodies. This antibody recognized a 38 kDa protein in extracts from maize embryonic axes which corresponds to the predicted size for cyclin D2 protein. Expression of cyclin D2 was followed at the transcriptional and protein levels, and the effect of cytokinins and abscisic acid (ABA) was followed during maize germination. Cytokinins importantly stimulated cyclin D2 gene expression at late germination times and sucrose was necessary for stimulation, whereas the effect of ABA was not different from that in controls. However, cyclin D2 protein levels in control axes reached a peak at 6 h germination, declining thereafter, and neither cytokinins nor ABA modified this behavior. Two cyclic-dependent kinase A (Cdk-A)-type proteins and proliferating cell nuclear antigen (PCNA) were found co-immunoprecipitating with cyclin D2, and these immunoprecipitates were able to phosphorylate both histone H1 and the maize retinoblastoma-related protein (RBR). This protein kinase activity differed from the pattern of protein accumulation during germination, and the activity was not modified by either cytokinins or ABA. We discuss these findings in terms of the importance of the cell cycle for the germination process.
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Claims 13
Claim · model-written summary
A cDNA encoding the maize cyclin D2 N terminus was cloned.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A cDNA corresponding to 16 kDa of the maize cyclin D2 N-terminus was cloned”
Claim · model-written summary
The antibody recognized a 38 kDa protein in maize embryonic axes matching the predicted cyclin D2 size.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This antibody recognized a 38 kDa protein in extracts from maize embryonic axes which corresponds to the predicted size for cyclin D2 protein.”
Claim · model-written summary
Cytokinins stimulated maize cyclin D2 gene expression late in germination.
- Treatment
- Cytokininse0
- Gene
- cyclin D2e0
- Outcome
- cyclin D2 gene expressione0
- Direction
- stimulatede0
- Qualifier
- late germination timese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytokinins importantly stimulated cyclin D2 gene expression at late germination times”
e1“maize germination”
Claim · model-written summary
Sucrose was necessary for cytokinin stimulation of maize cyclin D2 gene expression.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sucrose was necessary for stimulation”
e1“Cytokinins importantly stimulated cyclin D2 gene expression”
e2“maize germination”
Claim · model-written summary
ABA had an effect on cyclin D2 expression no different from controls.
- Treatment
- ABAe0
- Gene
- cyclin D2e1
- Outcome
- cyclin D2 gene expressione1
- Direction
- not differente0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of ABA was not different from that in controls.”
e1“cyclin D2 gene expression”
e2“maize germination”
Claim · model-written summary
Control maize embryonic axes cyclin D2 protein levels peaked at six hours of germination then declined.
- Organ / stage
- axese0
- Gene
- cyclin D2e0
- Outcome
- cyclin D2 protein levelse0
- Direction
- reached a peake0
- Value
- 6 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cyclin D2 protein levels in control axes reached a peak at 6 h germination, declining thereafter”
e1“maize germination”
Claim · model-written summary
Cytokinins did not modify the maize cyclin D2 protein accumulation pattern.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“neither cytokinins nor ABA modified this behavior”
e1“cyclin D2 protein levels in control axes reached a peak at 6 h germination”
e2“maize germination”
Claim · model-written summary
ABA did not modify the maize cyclin D2 protein accumulation pattern.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“neither cytokinins nor ABA modified this behavior”
e1“cyclin D2 protein levels in control axes reached a peak at 6 h germination”
e2“maize germination”
Claim · model-written summary
Two Cdk-A-type proteins and PCNA co-immunoprecipitated with cyclin D2.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two cyclic-dependent kinase A (Cdk-A)-type proteins and proliferating cell nuclear antigen (PCNA) were found co-immunoprecipitating with cyclin D2”
e1“maize germination”
Claim · model-written summary
Cyclin D2 immunoprecipitates phosphorylated histone H1 and maize RBR.
- Gene
- cyclin D2e1
- Outcome
- phosphorylate both histone H1 and the maize retinoblastoma-related protein (RBR)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these immunoprecipitates were able to phosphorylate both histone H1 and the maize retinoblastoma-related protein (RBR).”
e1“co-immunoprecipitating with cyclin D2”
e2“maize germination”
Claim · model-written summary
Kinase activity differed from the cyclin D2 protein accumulation pattern during maize germination.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This protein kinase activity differed from the pattern of protein accumulation during germination”
e1“maize germination”
Claim · model-written summary
Cytokinins did not modify cyclin D2-associated kinase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activity was not modified by either cytokinins or ABA.”
e1“This protein kinase activity”
e2“maize germination”
Claim · model-written summary
ABA did not modify cyclin D2-associated kinase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activity was not modified by either cytokinins or ABA.”
e1“This protein kinase activity”
e2“maize germination”
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