Rhodopsin-Like Ionic Gate Fabricated with Graphene Oxide and Isomeric DNA Switch for Efficient Photocontrol of Ion Transport.

Rhodopsin, composed of opsin and isomeric retinal, acts as the primary photoreceptor by converting light into electric signals. Inspired by rhodopsin, we have fabricated a light-regulated ionic gate on the basis of the design of a graphene oxide (GO)-biomimetic DNA-nanochannel architecture. In this design, photoswitchable azobenzene (Azo)-DNA is introduced to the surface of porous anodic alumina (PAA) membrane. With modulation of the interaction between the GO blocker and Azo-DNA via flexibly regulating trans and cis states of Azo under the irradiation of visible and ultraviolet light, alternatively, the ionic gate is switched between ON and OFF states. This newly constructed ionic gate can possess high efficiency for the control of ion transport because of the high blocking property of GO and the rather tiny path within the barrier layer which are both first employed to fabricate ionic gate. We anticipate that this rhodopsin-like ionic gate may provide a new model and method for the investigation of ion channel, ion function, and ion quantity. In addition, because of the advantages of simple fabrication, good biocompatibility, and universality, this bioinspired system may have potential applications as optical sensors, in photoelectric transformation, and in controllable drug delivery.

SLAC1 is required for plant guard cell S-type anion channel function in stomatal signalling.

Stomatal pores, formed by two surrounding guard cells in the epidermis of plant leaves, allow influx of atmospheric carbon dioxide in exchange for transpirational water loss. Stomata also restrict the entry of ozone--an important air pollutant that has an increasingly negative impact on crop yields, and thus global carbon fixation and climate change. The aperture of stomatal pores is regulated by the transport of osmotically active ions and metabolites across guard cell membranes. Despite the vital role of guard cells in controlling plant water loss, ozone sensitivity and CO2 supply, the genes encoding some of the main regulators of stomatal movements remain unknown. It has been proposed that guard cell anion channels function as important regulators of stomatal closure and are essential in mediating stomatal responses to physiological and stress stimuli. However, the genes encoding membrane proteins that mediate guard cell anion efflux have not yet been identified. Here we report the mapping and characterization of an ozone-sensitive Arabidopsis thaliana mutant, slac1. We show that SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1) is preferentially expressed in guard cells and encodes a distant homologue of fungal and bacterial dicarboxylate/malic acid transport proteins. The plasma membrane protein SLAC1 is essential for stomatal closure in response to CO2, abscisic acid, ozone, light/dark transitions, humidity change, calcium ions, hydrogen peroxide and nitric oxide. Mutations in SLAC1 impair slow (S-type) anion channel currents that are activated by cytosolic Ca2+ and abscisic acid, but do not affect rapid (R-type) anion channel currents or Ca2+ channel function. A low homology of SLAC1 to bacterial and fungal organic acid transport proteins, and the permeability of S-type anion channels to malate suggest a vital role for SLAC1 in the function of S-type anion channels.

[Peculiarities of ion transport of calcium in tumor cells under conditions of irradiation by ionizing radiation, chemopreparations and homeopathic means].

The goal of given investigation was to reveal an effect of different agents on ion transport of Ca2+ in tumor cells (Erlich's carcinomas). Ionizing radiation, antitumor preparation vinkristin as well as homeopathic means - stimulated phosphoric acid diluted at 10-14 were used. Small doses of radiation (0,05 and 0,1 Gr) always had a stimulating effect on ion transport even in combination with vinkristin, which separately always depressed it. Both separately and in any combination stimulated phosphoric acid always reinforced transmembrane ion transport. In regard to Ca2+ a hypothesis about its participation in the process of reparation of tumor cell has been suggested. At increasing of Ca2+ concentrations a transmembrane transport of this ion in the environment increases what induces strengthening of adhesive properties of the cell. However, it is known that in tumors these properties are decreased. Apparently, in this case two contrary processes - strengthening and decrease of adhesive properties take place pointing to the fact that there appear reparative forces in tumor process.

[Effect of beta-carotene oil and bee pollen on ion transport in rat brain slices following radiation-chemical exposure]. / Effekty beta-karotinovogo masla i pchelinoi obnozhki pri radiatsionno-khimicheskom vozdeistvii na ionnyi transport v srezakh mozga krys.

Chronic combined exposure to ionizing radiation with dose of 0.25 Gy and cadmium chloride or atrazine to be present in drinking water at five-fold Limited Permissible Concentration (LPC) values led to the additively reduced intercellular K+ level in rat brain, that was at first choice caused by the active ion transport disorders in the case of irradiation, and by the changes in membrane permeability in the case of toxic loading. Applying of beta-carotene oil and bee pollen both abolished radiation effects, but no chemical toxicant ones. Authors supposed the selective action of the observed drugs to be connected with antioxidant activities of them.

The effect of external Ca2+ and Ca(2+)-channel modulators on red-light-induced swelling of protoplasts of Phaseolus radiatus L.

Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250 microM. Swelling response declined when Ca2+ was supplied into the medium after red light irradiation. The Ca(2+)-chelator EGTA eliminated the red-light-induced swelling and 45Ca2+ accumulation in the protoplasts. In contrast, A23187, a Ca(2+)-ionophore, could mimic the effect of red light in darkness. These results indicate that Ca2+ may play a role in light signal transduction. In addition, swelling response was prevented by TFP and CPZ (both are CaM antagonists), implying the involvement of CaM in red-light-induced and Ca(2+)-dependent protoplast swelling.