The relationship between intramembranous particles and aquaporin molecules in the plasma membranes of normal rat skeletal muscles: a fracture-label study

The plasma membrane of skeletal muscles contains water channels such as aquaporin 4 (AQP4), aquaporin 3 (AQP3) and aquaporin 7 (AQP7). In dehydrated mice, we have recently reported the altered distribution of the aggregations of intramembranous particles (IMPs), such as orthogonal array (a crystal-like structure) and IMP cluster (a rosette-like structure) on the freeze-fractured skeletal muscle plasma membranes. In this fracture-label study, we first tested whether the orthogonal arrays (OAs) were composed of AQP4 in skeletal muscles and further analyzed the relationship between IMPs including IMP clusters and AQP3 molecules. As a result, many of the gold particles indicating AQP4 was associated with OAs (79%) by our fracture-label technique. On the other hand, approximately 50% of gold particles indicating AQP3 were associated with IMP clusters. Thus we confirmed that the OAs are composed of AQP4 in skeletal muscles, and further demonstrated that some of the IMP clusters are composed of AQP3 and may participate in maintaining osmotic homeostasis in skeletal myofibers. The fracture-label method is useful in investigating the molecular identification of membrane proteins such as AQP3 and AQP4.     

Hybrid Langmuir and Langmuir–Blodgett films composed of amphiphilic cyclodextrins and hydrophobic azobenzene derivative

Hybrid Langmuir and Langmuir–Blodgett (LB) films consisting of amphiphilic cyclodextrins (CDs) and hydrophobic azobenzene were fabricated. Due to the larger cross-sectional area of the CD core compared with the sum of the cross-sectional areas of the attached alkyl chains, the films had free space in the hydrophobic regions. Azo(p-Hexyl) having hydrophobic terminal chains was accommodated in the free space, whereas the usage of an azobenzene derivative bearing hydrophilic groups led to the phase separation. The average tilt angle of Azo(p-Hexyl) gave minima when the free space was just filled with Azo(p-Hexyl). Photoisomerization of azobenzenes in the hybrid LB films was studied.     

The Patterning and Proportion of Charged Residues in the Arginine-Rich Mixed-Charge Domain Determine the Membrane-Less Organelle Targeted by the Protein

Membrane-less organelles (MLOs) are formed by biomolecular liquid–liquid phase separation (LLPS). Proteins with charged low-complexity domains (LCDs) are prone to phase separation and localize to MLOs, but the mechanism underlying the distributions of such proteins to specific MLOs remains poorly understood. Recently, proteins with Arg-enriched mixed-charge domains (R-MCDs), primarily composed of R and Asp (D), were found to accumulate in nuclear speckles via LLPS. However, the process by which R-MCDs selectively incorporate into nuclear speckles is unknown. Here, we demonstrate that the patterning of charged amino acids and net charge determines the targeting of specific MLOs, including nuclear speckles and the nucleolus, by proteins. The redistribution of R and D residues from an alternately sequenced pattern to uneven blocky sequences caused a shift in R-MCD distribution from nuclear speckles to the nucleolus. In addition, the incorporation of basic residues in the R-MCDs promoted their localization to the MLOs and their apparent accumulation in the nucleolus. The R-MCD peptide with alternating amino acids did not undergo LLPS, whereas the blocky R-MCD peptide underwent LLPS with affinity to RNA, acidic poly-Glu, and the acidic nucleolar protein nucleophosmin, suggesting that the clustering of R residues helps avoid their neutralization by D residues and eventually induces R-MCD migration to the nucleolus. Therefore, the distribution of proteins to nuclear speckles requires the proximal positioning of D and R for the mutual neutralization of their charges.     

Making 2D Map of Environments Based upon Routes Scenes

This paper proposes a method for making a map of large scale environment based upon route scenes, assuming that the topological relation of routes at intersections is known. A panoramic representation is used for describing route scenes, and the number of routes connecting at an intersection is assumed to be known. The idea is to decompose a 2D graph into a number of closed loops. By detecting the closed loops and storing the relation among them, we can describe the 2D map based upon route scenes. A robot can obtain a closed loop by taking the same turn (leftmost for example) at every intersection when it moves along routes. According to the information on routes at intersections, the robot can select unmoved routes for finding new closed loops. By fusing new closed loops with found ones, the robot can, further, build the map of environments. The effectiveness of our method are shown by experiment in a real-world environment.     

Evaluation of the contents and ratios of five fractionated proteins to elucidate the protein composition in soybean seeds

Selecting suitable soybean cultivars is important for food processing and exploring their endowment with desirable physiological functions. We applied the fractionation method previously established to compare soy protein composition among cultivars to promote such a selection. More than 95% of the proteins in soybean cotyledons were extracted from 13 soybean cultivars using a high-concentration salt solution. The extracted proteins were fractionated into five fractions, namely oil body-associated protein (OBAP), polar lipid-associated protein (PLAP), globulins (11S and 7S), and whey by centrifugation after tuning the solubility behavior of the proteins with various solutions. Protein species in each fraction were analyzed by SDS-PAGE. Protein content in the total extract and five fractions was quantified to characterize the protein composition of soybean cultivars. The correlation between the protein content of each fraction and the total protein in cotyledon was investigated. A strong positive correlation was found only for the 11S fraction (r = 0.82), followed by a positive correlation in the 7S fraction (r = 0.65). Thus, we surmised that the increased protein content in soybean was due to increased globulin content. Furthermore, the calculation of the average ratio of protein content in each fraction indicated the globulin fraction (7S and 11S) to be 52%, the lipophilic protein fraction (OBAP and PLAP) to be 33%, and the whey fraction to be 13%. The preparation method employed in this study is a promising tool for efficiently comparing the protein composition of soybean cultivars to evaluate the potential use of cultivars for food production.     

Stereoselective Synthesis of (E)‐ and (Z)‐Allylphosphonium Salts by Palladium‐Catalyzed Addition of Phosphine to Allene

The palladium‐catalyzed addition of phosphine to allene in the presence of methanesulfonic acid stereoselectively gives the (E)‐ or (Z)‐allylphosphonium salt. The (E)‐allylphosphonium salt is formed by performing the reaction in THF under reflux and the (Z)‐allylphosphonium salt is obtained at –10 °C. The (E)‐ and (Z)‐allylphosphonium salts are used in the Wittig olefination reaction, and their diastereoselectivities are compared.