Fabrication of superhydrophobic surfaces is an area of great interest because it can be applicable to various engineering fields. A simple, safe and inexpensive fabrication process is required to fabricate applicable superhydrophobic surfaces. In this study, we developed a facile fabrication method of nearly perfect superhydrophobic surfaces through plasma treatment with argon and oxygen gases. A polytetrafluoroethylene (PTFE) sheet was selected as a substrate material. We optimized the fabrication parameters to produce superhydrophobic surfaces of superior performance using the Taguchi method. The contact angle of the pristine PTFE surface is approximately 111.0° ± 2.4°, with a sliding angle of 12.3° ± 6.4°. After the plasma treatment, nano-sized spherical tips, which looked like crown-structures, were created. This PTFE sheet exhibits the maximum contact angle of 178.9°, with a sliding angle less than 1°. As a result, this superhydrophobic surface requires a small external force to detach water droplets dripped on the surface. The contact angle of the fabricated superhydrophobic surface is almost retained, even after performing an air-aging test for 80 days and a droplet impacting test for 6 h. This fabrication method can provide superb superhydrophobic surface using simple one-step plasma etching.

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The repression of translation in environmentally stressed eukaryotic cells causes the sequestration of translation initiation factors and the 40S ribosomal subunit into discrete cytoplasmic foci called stress granules (SGs). Most components of the preinitiation complex, such as eIF3, eIF4A, eIF4E, eIF4G, and poly(A)-binding protein, congregate into SGs under stress conditions. However, the molecular basis of translation factor sequestration into SGs has not been clearly elucidated. Here, we report that proline-rich transcript in brain (PRTB) protein interacts with eIF4G and participates in SG formation. PRTB was recruited to SG under sodium arsenite and heat stress conditions. When overexpressed, PRTB inhibited global translation and formed SGs containing TIA-1, eIF4G, and eIF3. Knockdown of PRTB reduced the SG formation induced by sodium arsenite. These results suggest that PRTB not only is a component of SG formed by cellular stresses but also plays an important role in SG formation via an interaction with the scaffold protein eIF4G, which is associated with many translation factors and mRNAs.The translation rate of eukaryotic mRNAs is modulated by environmental conditions, with that of many mRNAs being inhibited when cells are stressed by heat, high osmolarity, oxidative chemicals, etc. (15). The translation inhibition causes the sequestration of translation initiation factors and the 40S ribosomal subunit into discrete cytoplasmic foci, called stress granules (SGs), that are formed in environmentally stressed eukaryotic cells (1, 2, 14-17, 19, 26, 30). The SGs contain most of the components of the 48S preinitiation complex (i.e., small [but not large] ribosomal subunits, eukaryotic initiation factor 4G [eIF4G], eIF3, eIF4E, eIF2, and eIF2B), other RNA-binding proteins, such as T-cell-restricted intracellular antigen-1 (TIA-1) and T-cell-restricted intracellular antigen-related protein (TIAR), and untranslated mRNAs (1, 2, 15-17). As a consequence, mRNA translation generally is inhibited under stress conditions (6, 31).eIF4G plays a pivotal role in the initiation of translation, since it recruits many translation factors [poly(A)-binding protein (PABP) (12), eIF4E (20, 23), eIF4A (13), and eIF3 (13)] and the translation modulator Mnk1 (a Ser/Thr kinase) to the 40S ribosomal subunit via protein-protein interactions (28, 37). Moreover, the signaling molecule TRAF2 has been shown to bind to eIF4GI, one of the two functional homologues of eIF4G, and to block proinflammatory signaling via the sequestration of TRAF2 at the SGs under stress conditions (18,25). This indicates that eIF4G plays important roles in the regulation of cellular activities such as translation and signal transduction.The proline-rich transcript of the brain (PRTB) protein, which is a 17-kDa protein, originally was isolated in a gene trap screen as a transcript expressed in the developing mouse inner ear (38). PRTB also is known as DAZAP2 [deleted-inazoospermia (DAZ)-associated protein 2], which was identified as a protein interacting with the...

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Regulation of water flow in an interconnected xylem vessel network enables plants to survive despite challenging environment changes that can cause xylem embolism. In this study, vulnerability to embolisms of xylem vessels and their water-refilling patterns in vascular bundles of maize leaves were experimentally investigated by employing synchrotron X-ray micro-imaging technique. A vascular bundle in maize consisted of a protoxylem vessel with helical thickenings between two metaxylem vessels with single perforation plates and nonuniformly distributed pits. When embolism was artificially induced in excised maize leaves by exposing them to air, protoxylem vessels became less vulnerable to dehydration compared to metaxylem vessels. After supplying water into the embolized vascular bundles, when water-refilling process stopped at the perforation plates in metaxylem vessels, discontinuous radial water influx occurred surprisingly in the adjacent protoxylem vessels. Alternating water refilling pattern in protoxylem and metaxylem vessels exhibited probable correlation between the incidence location and time of water refilling and the structural properties of xylem vessels. These results imply that the maintenance of water transport and modulation of water refilling are affected by hydrodynamic roles of perforation plates and radial connectivity in a xylem vascular bundle network.

HighlightDirect X-ray micro-imaging reveals localized xylem embolism under water stress conditions in the leaves of intact maize, with a specific spatial distribution of embolism in terms of xylem structure.

In vascular plants, the xylem network constitutes a complex microfluidic system. The relationship between vascular network architecture and functional hydraulic regulation during actual water flow remains unexplored. Here, we developed a method to visualize individual xylem vessels of the 3D xylem network of Arabidopsis thaliana, and to analyze the functional activities of these vessels using synchrotron X-ray computed tomography with hydrophilic gold nanoparticles as flow tracers. We show how the organization of the xylem network changes dynamically throughout the plant, and reveal how the elementary units of this transport system are organized to ensure both long-distance axial water transport and local lateral water transport. Xylem vessels form distinct clusters that operate as functional units, and the activity of these units, which determines water flow pathways, is modulated not only by varying the number and size of xylem vessels, but also by altering their interconnectivity and spatial arrangement. Based on these findings, we propose a regulatory model of water transport that ensures hydraulic efficiency and safety.

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