Abstract
Oscillatory growth of pollen tubes has been correlated with oscillatory influxes of the cations Ca(2+), H(+), and K(+). Using an ion-specific vibrating probe, a new circuit was identified that involves oscillatory efflux of the anion Cl(-) at the apex and steady influx along the tube starting at 12 microm distal to the tip. This spatial coupling of influx and efflux sites predicts that a vectorial flux of Cl(-) ion traverses the apical region. The Cl(-) channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino)benzoic acid completely inhibited tobacco pollen tube growth at 80 and 20 microM, respectively. Cl(-) channel blockers also induced increases in apical cell volume. The apical 50 micro m of untreated pollen tubes had a mean cell volume of 3905 +/- 75 microm(3). DIDS at 80 microM caused a rapid and lethal cell volume increase to 6206 +/- 171 microm(3), which is at the point of cell bursting at the apex. DIDS was further demonstrated to disrupt Cl(-) efflux from the apex, indicating that Cl(-) flux correlates with pollen tube growth and cell volume status. The signal encoded by inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P(4)] antagonized pollen tube growth, induced cell volume increases, and disrupted Cl(-) efflux. Ins(3,4,5,6)P(4) decreased the mean growth rate by 85%, increased the cell volume to 5997 +/- 148 microm(3), and disrupted normal Cl(-) efflux oscillations. These effects were specific for Ins(3,4,5,6)P(4) and were not mimicked by either Ins(1,3,4,5)P(4) or Ins(1,3,4,5,6)P(5). Growth correlation analysis demonstrated that cycles of Cl(-) efflux were coupled to and temporally in phase with cycles of growth. A role for Cl(-) flux in the dynamic cellular events during growth is assessed. Differential interference contrast microscopy and kymographic analysis of individual growth cycles revealed that vesicles can advance transiently to within 2 to 4 microm of the apex during the phase of maximally increasing Cl(-) efflux, which temporally overlaps the phase of cell elongation during the growth cycle. In summary, these investigations indicate that Cl(-) ion dynamics are an important component in the network of events that regulate pollen tube homeostasis and growth.
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Claims 12
Claim · model-written summary
Pollen tubes showed oscillatory apical chloride efflux and steady influx beyond the tip.
Verbatim
e0“oscillatory efflux of the anion Cl(-) at the apex and steady influx along the tube starting at 12 microm distal to the tip.”
t0“Pollen Tube”
Claim · model-written summary
DIDS completely inhibited tobacco pollen tube growth at 80 microM.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)e0
- Outcome
- tobacco pollen tube growthe0
- Direction
- inhibitede0
- Value
- 80 microMe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Cl(-) channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino)benzoic acid completely inhibited tobacco pollen tube growth at 80 and 20 microM, respectively.”
e1“DIDS at 80 microM caused a rapid and lethal cell volume increase to 6206 +/- 171 microm(3), which is at the point of cell bursting at the apex.”
Claim · model-written summary
The second chloride channel blocker completely inhibited tobacco pollen tube growth at 20 microM.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- 5-nitro-2-(3-phenylpropylamino)benzoic acide0
- Outcome
- tobacco pollen tube growthe0
- Direction
- inhibitede0
- Value
- 20 microMe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Cl(-) channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino)benzoic acid completely inhibited tobacco pollen tube growth at 80 and 20 microM, respectively.”
Claim · model-written summary
Chloride channel blockers increased apical cell volume.
Not reportedComparator
Verbatim
e0“Cl(-) channel blockers also induced increases in apical cell volume.”
t0“Pollen Tube”
Claim · model-written summary
At 80 microM DIDS increased apical cell volume to a bursting threshold.
- Taxon
- Pollen Tubet0
- Treatment
- DIDS at 80 microMe0
- Outcome
- cell volumee0
- Direction
- increasee0
- Value
- 6206 +/- 171 microm(3)e0
Not reportedComparator
Verbatim
e0“DIDS at 80 microM caused a rapid and lethal cell volume increase to 6206 +/- 171 microm(3), which is at the point of cell bursting at the apex.”
t0“Pollen Tube”
Claim · model-written summary
DIDS disrupted apical chloride efflux.
Not reportedComparator
Verbatim
e0“DIDS was further demonstrated to disrupt Cl(-) efflux from the apex”
t0“Pollen Tube”
Claim · model-written summary
Ins(3,4,5,6)P(4) lowered mean pollen tube growth rate by 85%.
- Taxon
- Pollen Tubet0
- Treatment
- Ins(3,4,5,6)P(4)e0
- Outcome
- mean growth ratee0
- Direction
- decreasede0
- Value
- 85%e0
Not reportedComparator
Verbatim
e0“Ins(3,4,5,6)P(4) decreased the mean growth rate by 85%”
t0“Pollen Tube”
Claim · model-written summary
Ins(3,4,5,6)P(4) increased pollen tube cell volume to 5997 +/- 148 microm(3).
- Taxon
- Pollen Tubet0
- Treatment
- Ins(3,4,5,6)P(4)e0
- Outcome
- cell volumee0
- Direction
- increasede0
- Value
- 5997 +/- 148 microm(3)e0
Not reportedComparator
Verbatim
e0“Ins(3,4,5,6)P(4) decreased the mean growth rate by 85%, increased the cell volume to 5997 +/- 148 microm(3)”
t0“Pollen Tube”
Claim · model-written summary
Ins(3,4,5,6)P(4) disrupted normal chloride efflux oscillations.
- Taxon
- Pollen Tubet0
- Treatment
- Ins(3,4,5,6)P(4)e0
- Outcome
- normal Cl(-) efflux oscillationse0
- Direction
- disruptede0
Not reportedComparator
Verbatim
e0“Ins(3,4,5,6)P(4) decreased the mean growth rate by 85%, increased the cell volume to 5997 +/- 148 microm(3), and disrupted normal Cl(-) efflux oscillations.”
t0“Pollen Tube”
Claim · model-written summary
Other tested inositol phosphates did not mimic these effects.
Verbatim
e0“These effects were specific for Ins(3,4,5,6)P(4) and were not mimicked by either Ins(1,3,4,5)P(4) or Ins(1,3,4,5,6)P(5).”
t0“Pollen Tube”
Claim · model-written summary
Chloride efflux cycles were coupled and in phase with growth cycles.
Not reportedDirection
Verbatim
e0“cycles of Cl(-) efflux were coupled to and temporally in phase with cycles of growth.”
t0“Pollen Tube”
Claim · model-written summary
Vesicles transiently approached within 2 to 4 microm of the apex during rising chloride efflux and elongation.
Verbatim
e0“vesicles can advance transiently to within 2 to 4 microm of the apex during the phase of maximally increasing Cl(-) efflux, which temporally overlaps the phase of cell elongation during the growth cycle.”
t0“Pollen Tube”
The same questions in other papers
4,4'-diisothiocyano-trans-stilbene-2,2'-disulfonic acid · growth · Nicotiana tabacum (tobacco)Results differ
1 paper in the same direction as this paper
- no effect
benzoic acid · growth · Nicotiana tabacum (tobacco)Results agree
2 papers in the same direction as this paper
- negative
- 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.