Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variation...

—Usually, for the design of UWB systems, the symbol duration is chosen larger than the delay of the channel impulse response, in order to avoid the ISI (inter symbol interference). However, this approach does not maximize the system capacity. An adaptation of the guard time (GT) is a flexible mean of exploiting system resources efficiently in a multi-path fading environment. The optimal guard ...

We isolated a total of 3 x 10(8) guard cell protoplasts from 22,000 Arabidopsis thaliana plants and identified 1734 unique proteins using three complementary proteomic methods: protein spot identification from broad and narrow pH range two-dimensional (2D) gels, and 2D liquid chromatography-matrix assisted laser desorption/ionization multidimensional protein identification technology. This exte...

Stomatal movements in response to environmental stimuli critically control the plant water status. Although these movements are governed by osmotically driven changes in guard cell volume, the role of membrane water channels (aquaporins) has remained hypothetical. Assays in epidermal peels showed that knockout Arabidopsis thaliana plants lacking the Plasma membrane Intrinsic Protein 2;1 (PIP2;1...

Voltage-dependent inward-rectifying (K(in)) and outward-rectifying (K(out)) K(+) channels are capable of mediating K(+) fluxes across the plasma membrane. Previous studies on guard cells or heterologously expressed K(+) channels provided evidence for the requirement of ATP to maintain K(+) channel activity. Here, the nucleotide and Mg(2+) dependencies of time-dependent K(in) and K(out) channels...

In cellular telephone system, some channels known as Guard Channels are used exclusively for handover calls. The impact of this is improvement in probability of successful handoffs. For efficient usage of these reserved channels knowledge of mobility patterns, channel occupancy time and rate of call arrival is required. The guard channel based call admission control scheme has some drawbacks, i...

Free cytosolic Ca(2+) ([Ca(2+)](cyt)) is an ubiquitous second messenger in plant cell signaling, and [Ca(2+)](cyt) elevation is associated with Ca(2+)-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca(2+) channels and their regulation remains limited in planta. A type of voltage-dependent Ca(2+)-permeable channel wa...

Sun’s nonrepudiation threshold proxy signature scheme is not secure against the collusion attack. In order to guard against the attack, Hwang et al. proposed another threshold proxy signature scheme. However, a new attack is proposed to work on both Hwang et al.’s and Sun’s schemes. By executing this attack, one proxy signer and the original signer can forge any valid proxy signature. Therefore...

Abscisic acid (ABA) stimulates stomatal closure and thus supports water conservation by plants during drought. Mass spectrometry-generated peptide sequence information was used to clone a Vicia faba complementary DNA, AAPK, encoding a guard cell-specific ABA-activated serine-threonine protein kinase (AAPK). Expression in transformed guard cells of AAPK altered by one amino acid (lysine 43 to al...

Reorganization of the cortical microtubule cytoskeleton is critical for guard cell function. Here, we investigate how environmental and hormonal signals cause these rearrangements and find that COP1, a RING-finger-type ubiquitin E3 ligase, is required for degradation of tubulin, likely by the 26S proteasome. This degradation is required for stomatal closing. In addition to regulating the cytosk...