New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards . This article abides by terms of the Creative Commons CC-by-sa License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing history of earlier contributions by wikipedians is accessible to researchers here:
Polyamines are also important modulators of a variety of ion channels , including NMDA receptors and AMPA receptors . They block inward-rectifier potassium channels so that the currents of the channels are inwardly rectified, thereby the cellular energy, . K +
ion gradient across the cell membrane, is conserved. In addition, polyamine participate in initiating the expression of SOS response of Colicin E7 operon and down-regulate proteins that are essential for colicin E7 uptake, thus conferring a survival advantage on colicin-producing E. coli under stress conditions. 
As a result of the problems with isolating florigen, and of the inconsistent results acquired, it has been suggested that florigen does not exist as an individual substance; rather, florigen's effect could be the result of a particular ratio of other hormones.   However, more recent findings indicate that florigen does exist and is produced, or at least activated, in the leaves of the plant and that this signal is then transported via the phloem to the growing tip at the shoot apical meristem where the signal acts by inducing flowering. In Arabidopsis thaliana , some researchers have identified this signal as mRNA coded by the FLOWERING LOCUS T ( FT ) gene, others as the resulting FT protein.  First report of FT mRNA being the signal transducer that moves from leaf to shoot apex came from the publication in Science Magazine. However, in 2007 other group of scientists made a breakthrough saying that it is not the mRNA, but the FT Protein that is transmitted from leaves to shoot possibly acting as "Florigen".  The initial article  that described FT mRNA as flowering stimuli was retracted by the authors themselves.