Abstract
Previous studies on the cell cycle of Arabidopsis thaliana have been hindered by the lack of synchronous cell culture systems. We have used liquid callus cultures and a cycloheximide-synchronized suspension culture of Arabidopsis to investigate changes in cyclin transcript levels in response to exogenous auxin, cytokinin, and nutrients, and during the cell cycle. CYCD1 (delta 1) transcript was virtually undetectable in liquid-cultured callus or suspension-culture cells. CYCD2 (delta 2) transcript levels were largely unaffected by the readdition of phytohormones or nitrate to the growth medium, and remained constant throughout the cell cycle in suspension-culture cells. CYCD3 (delta 3) transcript levels were strongly dependent on nitrate, and were induced at the G1/S transition following phytohormone readdition. In synchronized suspension-culture cells, CYCD3 transcript accumulated during the S phase, and remained constant thereafter. These results support the hypothesis that D cyclins function as part of the cellular machinery that integrates diverse signals impinging upon commitment to cell division. In synchronized cells transcripts of the mitotic cyclins CYC1, CYC2, and CYC3 reached a maximum with peak mitotic index, but CYC3 transcript levels increased earlier than those of CYC1 or CYC2. The kinetics of accumulation of CYC transcript levels support their classification as A-type (CYC3) and B-type (CYC1 and CYC2) cyclins, respectively.
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Claims 11
Claim · model-written summary
CYCD1 transcript was virtually undetectable in callus and suspension cells.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Organ / stage
- liquid-cultured callus or suspension-culture cellse0
- Gene
- CYCD1e0
- Outcome
- transcript was virtually undetectablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYCD1 (delta 1) transcript was virtually undetectable in liquid-cultured callus or suspension-culture cells”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD2 transcript levels were largely unaffected by phytohormone or nitrate readdition.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- readdition of phytohormones or nitratee0
- Gene
- CYCD2e0
- Outcome
- transcript levelse0
- Direction
- largely unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYCD2 (delta 2) transcript levels were largely unaffected by the readdition of phytohormones or nitrate to the growth medium”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD2 transcript levels remained constant throughout the cell cycle.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Organ / stage
- suspension-culture cellse0
- Gene
- CYCD2e1
- Outcome
- transcript levelse1
- Direction
- remained constante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“remained constant throughout the cell cycle in suspension-culture cells”
e1“CYCD2 (delta 2) transcript levels”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD3 transcript levels depended strongly on nitrate.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYCD3e0
- Compound
- nitratee0
- Outcome
- transcript levelse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYCD3 (delta 3) transcript levels were strongly dependent on nitrate”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD3 transcripts were induced at the G1/S transition following phytohormone readdition.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Organ / stage
- G1/S transitione0
- Treatment
- phytohormone readditione0
- Gene
- CYCD3e1
- Outcome
- transcript levelse1
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were induced at the G1/S transition following phytohormone readdition”
e1“CYCD3 (delta 3) transcript levels”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD3 transcript accumulated during S phase.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Organ / stage
- S phasee0
- Gene
- CYCD3e0
- Outcome
- transcript accumulatede0
- Direction
- accumulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYCD3 transcript accumulated during the S phase”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYCD3 transcript remained constant after S phase.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYCD3e0
- Outcome
- transcripte0
- Direction
- remained constante0
- Qualifier
- thereaftere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYCD3 transcript accumulated during the S phase, and remained constant thereafter”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYC1, CYC2 and CYC3 transcripts peaked with the mitotic index.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYC1, CYC2, and CYC3e0
- Outcome
- transcriptse0
- Direction
- reached a maximume0
- Qualifier
- with peak mitotic indexe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transcripts of the mitotic cyclins CYC1, CYC2, and CYC3 reached a maximum with peak mitotic index”
t0“Arabidopsis thaliana”
Claim · model-written summary
CYC3 transcript levels increased earlier than CYC1 or CYC2.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYC3e0
- Outcome
- transcript levelse0
- Direction
- increased earliere0
- Comparator
- CYC1 or CYC2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYC3 transcript levels increased earlier than those of CYC1 or CYC2”
t0“Arabidopsis thaliana”
Claim · model-written summary
The transcript kinetics support classifying CYC3 as an A-type cyclin.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYC3e0
- Outcome
- A-type (CYC3)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The kinetics of accumulation of CYC transcript levels support their classification as A-type (CYC3) and B-type (CYC1 and CYC2) cyclins, respectively”
t0“Arabidopsis thaliana”
Claim · model-written summary
The transcript kinetics support classifying CYC1 and CYC2 as B-type cyclins.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- CYC1 and CYC2e0
- Outcome
- B-type (CYC1 and CYC2) cyclinse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The kinetics of accumulation of CYC transcript levels support their classification as A-type (CYC3) and B-type (CYC1 and CYC2) cyclins, respectively”
t0“Arabidopsis thaliana”
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