Fluorocarbon-Free Dual-Action Textile Finishes Based on Covalently Attached Thermoresponsive Block Copolymer Brush Coatings.

We present fluorocarbon-free block copolymer brushes as potential systems for dual-action, i.e., soil-repellent and soil-releasing textile finishes. Polymer brushes were prepared by employing specifically engineered triblock copolymers consisting of a hydrophobic, a hydrophilic, and either a central or a terminal anchor block bearing several anchoring groups for sustainable immobilization using the "grafting to" approach on both flat Si wafers and rough cotton fabrics. The switching characteristics of both types of block copolymer brushes were investigated by exposing the brushes to conditions and stimuli that are similar to those applied during laundering in a washing machine and drying in a laundry dryer, respectively. Contact angle measurements were performed to evaluate the polarity and wettability of the block copolymer brushes after treatment in hot water and in air, or in a vacuum at elevated temperatures simulating the washing and the drying procedure of a textile fabric. While the block copolymer brush with the terminal anchor showed only minor changes in terms of the wetting characteristics and the brush morphology upon the applied stimuli, the block copolymer brush with the central anchoring block exhibited a significant change from a hydrophilic (soil-releasing) to a hydrophobic (stain-repellent) surface. This switching behavior was reversible and could be achieved on both, flat Si wafers, and much more pronounced on rough cotton fabrics. Atomic force microscopy and angle-resolved X-ray photoelectron spectroscopy investigations further indicated a complete rearrangement of the brush morphology. Accordingly, we regard this type of block copolymer brushes as a system that fully meets the basic requirements for an application as a dual-action textile finish, which can be reversibly switched with respect to water repulsion.

The maize (Zea mays L.) roothairless3 gene encodes a putative GPI-anchored, monocot-specific, COBRA-like protein that significantly affects grain yield.

The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize (Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3 based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested. In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield.

The Etched1 gene of Zea mays (L.) encodes a zinc ribbon protein that belongs to the transcriptionally active chromosome (TAC) of plastids and is similar to the transcription factor TFIIS.

Etched1 (et1) is a pleiotropic, recessive mutation of maize that causes fissured and cracked mature kernels and virescent seedlings. Microscopic examinations of the et1 phenotype revealed an aberrant plastid development in mutant kernels and mutant leaves. Here, we report on the cloning of the et1 gene by transposon tagging, the localization of the gene product in chloroplasts, and its putative function in the plastid transcriptional apparatus. Several alleles of Mutator (Mu)-induced et1 mutants, the et1-reference (et1-R) mutant, and Et1 wild-type were cloned and analyzed at the molecular level. Northern analyses with wild-type plants revealed that Et1 transcripts are present in kernels, leaves, and other types of tissue, and no Et1 expression could be detected in the et1 mutants analyzed. The ET1 protein is imported by chloroplasts and has been immunologically detected in transcriptionally active chromosome (TAC) fractions derived from chloroplasts. Accordingly, the relative transcriptional activity of TAC fractions was significantly reduced in chloroplasts of et1-R plants. ET1 is the first zinc ribbon (ZR) protein shown to be targeted to plastids. With regard to its localization and its striking structural similarity to the eukaryotic transcription elongation factor TFIIS, it is feasible that ET1 functions in plastid transcription elongation by reactivation of arrested RNA polymerases.