Pollen tube cell volume changes rapidly in response to perturbation of the extracellular osmotic potential. This report shows that specific phospholipid signals are differentially stimulated or attenuated during osmotic perturbations. Hypo-osmotic stress induces rapid increases in phosphatidic acid (PA). This response occurs starting at the addition of 25% (v/v) water to the pollen tube cultures and peaks at 100% (v/v) water. Increased levels of PA were detected within 30 s and reached maximum by 15 to 30 min after treatment. The pollen tube apical region undergoes a 46% increase in cell volume after addition of 100% water (v/v), and there is an average 7-fold increase in PA. This PA increase appears to be generated by phospholipase D because concurrent transphosphatidylation of n-butanol results in an average 8-fold increase in phosphatidylbutanol. Hypo-osmotic stress also induces an average 2-fold decrease in phosphatidylinositol phosphate; however, there are no detectable changes in the levels of phosphatidylinositol bisphosphates. In contrast, salt-induced hyperosmotic stress from 50 to 400 mm NaCl inhibits phospholipase D activity, reduces the levels of PA, and induces increases in the levels of phosphatidylinositol bisphosphate isomers. The pollen tube apical region undergoes a 41% decrease in cell volume at 400 mm NaCl, and there is an average 2-fold increase in phosphatidylinositol 3,5-bisphosphate and 1.4-fold increase in phosphatidylinositol 4,5-bisphosphate. The phosphatidylinositol 3,5-bisphosphate increase is detected within 30 s and reaches maximum by 15 to 30 min after treatment. In summary, these results demonstrate that hypo-osmotic versus hyperosmotic perturbation and the resultant cell swelling or shrinking differentially activate specific phospholipid signaling pathways in tobacco (Nicotiana tabacum) pollen tubes.

• MeSH
• chlorid sodný farmakologie   MeSH
• fosfatidylinositol-4,5-difosfát biosyntéza   MeSH
• fosfatidylinositolfosfáty biosyntéza   MeSH
• fosfolipasa D účinky léků   metabolismus   MeSH
• fosfolipidy metabolismus   MeSH
• květy růst a vývoj   metabolismus   MeSH
• kyseliny fosfatidové biosyntéza   MeSH
• osmotický tlak účinky léků   MeSH
• signální transdukce účinky léků   fyziologie   MeSH
• tabák růst a vývoj   metabolismus   MeSH
• voda farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorid sodný MeSH
• fosfatidylinositol-4,5-difosfát MeSH
• fosfatidylinositolfosfáty MeSH
• fosfolipasa D MeSH
• fosfolipidy MeSH
• kyseliny fosfatidové MeSH
• phosphatidylinositol 3,5-diphosphate MeSH Prohlížeč
• voda MeSH

Pollen tube growth is a dynamic system expressing a number of oscillating circuits. Our recent work identified a new circuit, oscillatory efflux of Cl(-) anion from the pollen tube apex. Cl(-) efflux is the first ion signal found to be coupled in phase with growth oscillations. Functional analyses indicate an active role for Cl(-) flux in pollen tube growth. In this report the dynamical properties of Cl(-) efflux are examined. Phase space analysis demonstrates that the system trajectory converges on a limit cycle. Fourier analysis reveals that two harmonic frequencies characterize normal growth. Cl(-) efflux is inhibited by the channel blocker DIDS, is stimulated by hypoosmotic treatment, and is antagonized by the signal encoded in inositol 3,4,5,6-tetrakisphosphate. These perturbations induce transitions of the limit cycle to new metastable states or cause system collapse to a static attractor centered near the origin. These perturbations also transform the spectral profile, inducing subharmonic frequencies, transitions to period doubling and tripling, superharmonic resonance, and chaos. These results indicate that Cl(-) signals in pollen tubes display features that are characteristic of active oscillators that carry frequency-encoded information. A reaction network of the Cl(-) oscillator coupled to two nonlinear feedback circuits that may drive pollen tube growth oscillations is considered.

• MeSH
• biologické modely * MeSH
• chlor farmakokinetika   MeSH
• chloridové kanály účinky léků   fyziologie   MeSH
• Fourierova analýza MeSH
• gating iontového kanálu účinky léků   fyziologie   MeSH
• homeostáza fyziologie   MeSH
• inositolfosfáty farmakologie   MeSH
• kultivované buňky MeSH
• kyselina 4,4'-diisothiokyanostilben-2,2'-disulfonová farmakologie   MeSH
• nelineární dynamika MeSH
• oscilometrie metody   MeSH
• osmotický tlak MeSH
• periodicita MeSH
• počítačové zpracování signálu MeSH
• pyl fyziologie   MeSH
• tabák fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• publikace stažené z tisku MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• Názvy látek
• chlor MeSH
• chloridové kanály MeSH
• inositolfosfáty MeSH
• kyselina 4,4'-diisothiokyanostilben-2,2'-disulfonová MeSH