Endogenous oscillations of electric potential difference in the cambial region of the pine stem. II. Possible involvement of the oscillations in xylogenesis

Direct and indirect interrelations between xylogenic processes and the endogenous electric potential difference (PD) oscillations generated in the cambial region of isolated tissue blocks from pine trunks were investigated. The frequency of transient PD changes varied during the season and displayed three minima which were concurrent with periods of initiation and termination of cambial activity and with the time of transition from early- to late-wood production. The oscillations were damped by TIBA - an inhibitor of polar auxin transport and stimulated by IAA, but only when the hormone was supplied to the apical end of the tissue block. This suggests that the polar transport of auxin may be involved in generation of the transient PD changes. Results of 2-channel recordings in one tissue block suggest that a part of the recorded oscillations (10-25 %) exhibit coordination in space and time: a wave-like pattern along the trunk axis is created by PD changes. The pattern might be a physical carrier of information coordinating processes of growth and differentiation in distant parts of the tree.

Download Full-text

Electric potential differences across auroral generator interfaces

Annales Geophysicae ◽

10.5194/angeo-31-251-2013 ◽

2013 ◽

Vol 31 (2) ◽

pp. 251-261 ◽

Cited By ~ 11

Author(s):

J. De Keyser ◽

M. Echim

Keyword(s):

Electric Field ◽

High Altitude ◽

Electric Fields ◽

Electric Potential ◽

Equilibrium Configuration ◽

Potential Difference ◽

Field Profile ◽

Electric Potential Difference ◽

Electric Field Profile

Abstract. Strong localized high-altitude auroral electric fields, such as those observed by Cluster, are often associated with magnetospheric interfaces. The type of high-altitude electric field profile (monopolar, bipolar, or more complicated) depends on the properties of the plasmas on either side of the interface, as well as on the total electric potential difference across the structure. The present paper explores the role of this cross-field electric potential difference in the situation where the interface is a tangential discontinuity. A self-consistent Vlasov description is used to determine the equilibrium configuration for different values of the transverse potential difference. A major observation is that there exist limits to the potential difference, beyond which no equilibrium configuration of the interface can be sustained. It is further demonstrated how the plasma densities and temperatures affect the type of electric field profile in the transition, with monopolar electric fields appearing primarily when the temperature contrast is large. These findings strongly support the observed association of monopolar fields with the plasma sheet boundary. The role of shear flow tangent to the interface is also examined.

Download Full-text

Electric potential difference between conjugate points in middle latitudes caused by asymmetric dynamo in the ionosphere.

Journal of geomagnetism and geoelectricity ◽

10.5636/jgg.31.401 ◽

1979 ◽

Vol 31 (3) ◽

pp. 401-409 ◽

Cited By ~ 30

Author(s):

Naoshi FUKUSHIMA

Keyword(s):

Electric Potential ◽

Potential Difference ◽

Conjugate Points ◽

Middle Latitudes ◽

Electric Potential Difference

Download Full-text

The Necessity of an Electric Potential Difference and its Use for Photophosphorylation in Short Flash Groups

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1970.tb00326.x ◽

1970 ◽

Vol 14 (3) ◽

pp. 575-581 ◽

Cited By ~ 137

Author(s):

Wolfgang Junge ◽

Bernd Rumberg ◽

Hartmut Schroder

Keyword(s):

Electric Potential ◽

Potential Difference ◽

Electric Potential Difference

Download Full-text

Auxin minimum triggers the developmental switch from cell division to cell differentiation in the Arabidopsis root

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1705833114 ◽

2017 ◽

Vol 114 (36) ◽

pp. E7641-E7649 ◽

Cited By ~ 81

Author(s):

Riccardo Di Mambro ◽

Micol De Ruvo ◽

Elena Pacifici ◽

Elena Salvi ◽

Rosangela Sozzani ◽

...

Keyword(s):

Cell Division ◽

Auxin Transport ◽

Positional Information ◽

Polar Auxin Transport ◽

Arabidopsis Root ◽

Polar Transport ◽

Stringent Control ◽

Auxin Polar Transport ◽

Multicellular Organisms ◽

Developmental Switch

In multicellular organisms, a stringent control of the transition between cell division and differentiation is crucial for correct tissue and organ development. In the Arabidopsis root, the boundary between dividing and differentiating cells is positioned by the antagonistic interaction of the hormones auxin and cytokinin. Cytokinin affects polar auxin transport, but how this impacts the positional information required to establish this tissue boundary, is still unknown. By combining computational modeling with molecular genetics, we show that boundary formation is dependent on cytokinin’s control on auxin polar transport and degradation. The regulation of both processes shapes the auxin profile in a well-defined auxin minimum. This auxin minimum positions the boundary between dividing and differentiating cells, acting as a trigger for this developmental transition, thus controlling meristem size.

Download Full-text