The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes

We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism's vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 μrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.

Quantitative morphological transformation of vascular bundles in the culm of moso bamboo (Phyllostachys pubescens)

Vascular bundles of bamboo are determinants for mechanical properties of bamboo material and for physiological properties of living bamboo. The morphology of vascular bundles reflecting mechanical and physiological functions differs not only within internode tissue but also among different internodes in the culm. Although the distribution of vascular bundle fibers has received much attention, quantitative evaluation of the morphological transformation of vascular bundles associated with spatial distribution patterns has been limited. In this study deep learning models were used to determine quantitative changes in the distribution and morphology of vascular bundles in the culms of moso bamboo (Phyllostachys pubescens). A precise model for extracting vascular bundles from cross-sectional images was constructed using the U-Net model. Analyses of extracted vascular bundles from different internodes showed significant changes in vascular bundle distribution and morphology among internodes. Vascular bundles in lower internodes showed outer relative position and larger area than those in upper internodes. Aspect ratio and eccentricity indicate that vascular bundles in internodes near the base have more elliptical morphology, with a long axis in the radial direction. The variational autoencoder model using extracted vascular bundles enabled simulation of the morphological transformation of vascular bundles along with radial direction. These deep learning models enabled highly accurate quantification of vascular bundle morphologies, and will contribute to a further understanding of bamboo development as well as evaluation of the mechanical and physiological properties of bamboo.

Nuclear and magnetic spin structure of the antiferromagnetic triangular lattice compound LiCrTe2 investigated by [Formula: see text]SR, neutron and X-ray diffraction

Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe[Formula: see text], being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation ([Formula: see text]SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe[Formula: see text]. From high-resolution NPD the magnetic spin order at base-temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the ab-plane and AFM coupling along the c-axis. The value if the ordered magnetic Cr moment is established as [Formula: see text]. From detailed [Formula: see text]SR measurements we observe an AFM ordering temperature [Formula: see text] K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From [Formula: see text]SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe[Formula: see text] in the 3D Heisenberg AFM universality class. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices. This suggests the possibility for a strong magnon-phonon coupling, similar to what has been previously observed in the closely related compound LiCrO[Formula: see text].

Limiting silicon supply alters lignin content and structures of sorghum seedling cell walls

Sorghum has been recognized as a promising energy crop. The composition and structure of lignin in the cell wall are important factors that affect the quality of plant biomass as a bioenergy feedstock. Silicon (Si) supply may affect the lignin content and structure, as both Si and lignin are possibly involved in plant mechanical strength. However, our understanding regarding the interaction between Si and lignin in sorghum is limited. Therefore, in this study, we analyzed the lignin in the cell walls of sorghum seedlings cultured hydroponically with or without Si supplementation. Limiting the Si supply significantly increased the thioglycolic acid lignin content and thioacidolysis-derived syringyl/guaiacyl monomer ratio. At least part of the modification may be attributable to the change in gene expression, as suggested by the upregulation of phenylpropanoid biosynthesis-related genes under -Si conditions. The cell walls of the -Si plants had a higher mechanical strength and calorific value than those of the +Si plants. These results provide some insights into the enhancement of the value of sorghum biomass as a feedstock for energy production by limiting Si uptake.

Computer vision-based wood identification and its expansion and contribution potentials in wood science: A review

The remarkable developments in computer vision and machine learning have changed the methodologies of many scientific disciplines. They have also created a new research field in wood science called computer vision-based wood identification, which is making steady progress towards the goal of building automated wood identification systems to meet the needs of the wood industry and market. Nevertheless, computer vision-based wood identification is still only a small area in wood science and is still unfamiliar to many wood anatomists. To familiarize wood scientists with the artificial intelligence-assisted wood anatomy and engineering methods, we have reviewed the published mainstream studies that used or developed machine learning procedures. This review could help researchers understand computer vision and machine learning techniques for wood identification and choose appropriate techniques or strategies for their study objectives in wood science.

Anatomical Properties and Near Infrared Spectra Characteristics of Four Shorea Species from Indonesia

This study investigated the anatomical properties and absorbance characteristics of NIR spectra of four Shorea species from Indonesia. Macroscopic section revealed that Balau has similarity with Heavy Red Meranti, whereas White Meranti was almost identical with Light Red Meranti. All of the woods have diffuse porous and axial resin canals in tangential lines at the microscopic level. Original NIR spectra of Shorea species showed different absorbance characteristic. Wood density was assumed to be one of the factors that affected to the absorbances. Principal component analysis (PCA) of second derivative NIR spectra at the wavenumber 8,000-4,000 cm-1 (full) and 6,200-5,600 cm-1 (specific) showed different orientation among the Principal Component (PC) number. PC1, which contained highest spectral variation, had two closed clusters (1) Balau and Heavy Red Meranti and (2) White and Light Red Meranti at full spectral range. In contrast, the results at specific range were (1) Balau and White Meranti and (2) Heavy and Light Red Meranti. Hierarchical clustering dendrogram using PCA data from two spectral regions resulted in two types of clustering, the 8,000-4,000 cm-1 was somehow related to ‘density’, while the 6,200-5,600 cm-1 was grouped in ‘color’ information from visual inspection.  From both spectral regions, k-nearest neighbour (k-NN) classification models revealed 100% accuracy in identification four Shorea species using NIR spectra.

Dual Response of Photonic Films with Chiral Nematic Cellulose Nanocrystals: Humidity and Formaldehyde

Manipulating functional stimuli-responsive materials has been a hot topic in the research of smart sensors and anticounterfeiting encryption. Here, a novel functional chiral nematic cellulose nanocrystal (CNC) film showing dual responsiveness to humidity and formaldehyde gas was fabricated. The chiral nematic CNC iridescent film could respond to environmental humidity and formaldehyde gas changes by reversible motion. Interestingly, the humidity sensitivity of the CNC iridescent film could be gated by exposing the film to formaldehyde gas. At the same time, the formaldehyde-responsive behavior is strongly affected by the relative humidity (RH), and the response range could be tuned by changing the RH over a wide range. Importantly, the formaldehyde-induced color change could be altered from invisible to visible by the naked eye when the film was exposed to a humid environment. The mechanism of this dual response of the CNC iridescent film is ascribed to the synergistic effect of cooperation and competition between water and formaldehyde molecules by constructing physical cross-linking networks by hydrogen bonds among water, formaldehyde, and CNCs. Furthermore, the "RH-concentration of formaldehyde gas-color" ternary colorimetric system was simulated, which is thought to endow the CNC iridescent film with great potential to act as a sensor in the convenient visible detection of gaseous formaldehyde. Furthermore, this work provided a promising strategy to design multi-gas-sensitive devices with convenient detection, good stability, and excellent reversibility.

Bi-Arrhenius Diffusion and Surface Trapping of ^{8}Li^{+} in Rutile TiO_{2}

We report measurements of the diffusion rate of isolated ion-implanted ^{8}Li^{+} within ∼120  nm of the surface of oriented single-crystal rutile TiO_{2} using a radiotracer technique. The α particles from the ^{8}Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of ^{8}Li evolves with time. The main findings are that the implanted Li^{+} diffuses and traps at the (001) surface. The T dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-T barrier.

Anatomical features of Fagaceae wood statistically extracted by computer vision approaches: Some relationships with evolution

The anatomical structure of wood is complex and contains considerable information about its specific species, physical properties, growth environment, and other factors. While conventional wood anatomy has been established by systematizing the xylem anatomical features, which enables wood identification generally up to genus level, it is difficult to describe all the information comprehensively. This study apply two computer vision approaches to optical micrographs: the scale-invariant feature transform algorithm and connected-component labelling. They extract the shape and pore size information, respectively, statistically from the whole micrographs. Both approaches enable the efficient detection of specific features of 18 species from the family Fagaceae. Although the methods ignore the positional information, which is important for the conventional wood anatomy, the simple information on the shape or size of the elements is enough to describe the species-specificity of wood. In addition, according to the dendrograms calculated from the numerical distances of the features, the closeness of some taxonomic groups is inconsistent with the types of porosity, which is one of the typical classification systems for wood anatomy, but consistent with the evolution based on molecular phylogeny; for example, ring-porous group Cerris and radial-porous group Ilex are nested in the same cluster. We analyse which part of the wood structure gave the taxon-specific information, indicating that the latewood zone of group Cerris is similar to the whole zone of group Ilex. Computer vision approaches provide statistical information that uncovers new aspects of wood anatomy that have been overlooked by conventional visual inspection.

Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites

The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering.

Health-Risk Appraisal Applied to Ordinary AMHTS

The main purpose of an automatic health testing system (AMHTS) has changed from early detection to primary prevention. Health-risk appraisal is now widely available as a tool of health education aiming at the modification of unhealthy lifestyles. However, the opportunity to offer appropriate health education was less frequent for those who had no particular findings during AMHTS. The results of an AMHTS should be evaluated from the viewpoint of health-risk appraisal, because the system is expected to supply useful information regarding one’s lifestyle. Our system consists of two health-risk appraisal subsystems. One subsystem estimates the degree of improvement in medical indicators after a patient’s lifestyle has been modified. The other subsystem predicts the occurrence of abnormal findings in medical indicators. These health-risk appraisal subsystems provide patients with information about their health-risks, based on their AMHTS results. Our health-risk appraisal subsystems should play an important role in future health education through the application of ordinary AMHTS.

Outstanding Toughness of Cherry Bark Achieved by Helical Spring Structure of Rigid Cellulose Fiber Combined with Flexible Layers of Lipid Polymers

Cellulose, a main component of cell walls, generally makes materials hard and brittle. However, an ultratough, cellulosic material is found in nature: cherry bark. Surprisingly, it elongates by more than twice of its initial length and behaves as a plastic film during stretching. This amazing mechanical property is achieved by a well-designed cell wall structure; cellulose fibers are folded like helical springs, covered by multiple flexible layers of lipid polymers.

Characterization of crystalline linear (1→3)-α-d-glucan synthesized in vitro

We investigated the crystal structure and molecular arrangement of the linear (1→3)-α-d-glucan synthesized by glucosyltransferase GtfJ cloned from Streptococcus salivarius using sucrose as a substrate. The synthetic products had two morphologies: wavy fibril-like crystals as major and thin lamellae as minor products. Their structures were analyzed using electron microdiffraction, synchrotron X-ray powder diffraction, and solid-state ¹³C NMR spectroscopy. The fibrils and lamellae had the same allomorphic form but different molecular arrangements. The wet crystals were in a hydrated form, which converted into an anhydrous form with a significant decrease in crystallinity on drying. The hydrated and anhydrous forms had an extended-chain conformation with 2/1 helix, and the hydrated form was estimated to contain one water molecule per glucose residue. The long glucan chains were folded in the fibril crystals, while the short, extended chains were arranged perpendicular to the base plane of the lamellae.

Tuning the Viscoelasticity of Peptide Vesicles by Adjusting Hydrophobic Helical Blocks Comprising Amphiphilic Polypeptides

Amphiphilic block polypeptides of poly(sarcosine)-b-(l-Val-Aib)₆ and poly(sarcosine)-b-(l-Leu-Aib)₆ and their stereoisomers were self-assembled in water. Three kinds of binary systems of poly(sarcosine)-b-(l-Leu-Aib)₆ with poly(sarcosine)-b-poly(d-Leu-Aib)₆, poly(sarcosine)-b-poly(l-Val-Aib)₆, or poly(sarcosine)-b-(d-Val-Aib)₆ generated vesicles of ca. 200 nm diameter. The viscoelasticity of the vesicle membranes was evaluated by the nanoindentation method using AFM in water. The elasticity of the poly(sarcosine)-b-(l-Leu-Aib)₆/poly(sarcosine)-b-poly(d-Leu-Aib)₆ vesicle was 11-fold higher than that of the egg yolk liposome but decreased in combinations of the Leu- and Val-based amphiphilic polypeptides. The membrane elasticity is found to be adjustable by a suitable combination of helical blocks in terms of stereocomplex formation and the interdigitation of side chains among helices in the molecular assemblies.

Fibrillar assembly of bacterial cellulose in the presence of wood-based hemicelluloses

Composite materials mimicking the plant cell wall structure were made by culturing cellulose-producing bacteria together with secondary-wall hemicelluloses from wood. The effects of spruce galactoglucomannan (GGM) and beech xylan on the nanoscale morphology of bacterial cellulose were studied in the original, hydrated state with small-angle X-ray scattering (SAXS). The SAXS intensities were fitted with a model covering multiple levels of the hierarchical structure. Additional information on the structure of dried samples was obtained using scanning and transmission electron microscopy and infra-red spectroscopy. Both hemicelluloses induced a partial conversion of the cellulose crystal structure from I_α to I_β and a reduction of the cross-sectional dimensions of the cellulose microfibrils, thereby affecting also their packing into bundles. The differences were more pronounced in samples with xylan instead of GGM, and they became more significant with higher hemicellulose concentrations.

Unsymmetric vesicles with a different design on each side for near-infrared fluorescence imaging of tumor tissues

A new method for preparation of unsymmetric vesciles about chemical decoration of the outer or inner surface of the membrane makes it improved for tumor imaging.

Functional reconstitution of cellulose synthase in Escherichia coli

Cellulose is a high molecular weight polysaccharide of β1 → 4-d-glucan widely distributed in nature-from plant cell walls to extracellular polysaccharide in bacteria. Cellulose synthase, together with other auxiliary subunit(s) in the cell membrane, facilitates the fibrillar assembly of cellulose polymer chains into a microfibril. The gene encoding the catalytic subunit of cellulose synthase is cesA and has been identified in many cellulose-producing organisms. Very few studies, however, have shown that recombinant CesA protein synthesizes cellulose polymer, but the mechanism by which CesA protein synthesizes cellulose microfibrils is not known. Here we show that cellulose-synthesizing activity is successfully reconstituted in Escherichia coli by expressing the bacterial cellulose synthase complex of Gluconacetobacter xylinus: CesA and CesB (formerly BcsA and BcsB, respectively). Cellulose synthase activity was, however, only detected when CesA and CesB were coexpressed with diguanyl cyclase (DGC), which synthesizes cyclic-di-GMP (c-di-GMP), which in turn activates cellulose-synthesizing activity in bacteria. Direct observation by electron microscopy revealed extremely thin fibrillar structures outside E. coli cells, which were removed by cellulase treatment. This fiber structure is not likely to be the native crystallographic form of cellulose I, given that it was converted to cellulose II by a chemical treatment milder than ever described. We thus putatively conclude that this fine fiber is an unprecedented structure of cellulose. Despite the inability of the recombinant enzyme to synthesize the native structure of cellulose, the system described in this study, named "CESEC (CEllulose-Synthesizing E. Coli)", represents a useful tool for functional analyses of cellulose synthase and for seeding new nanomaterials.

Facile and precise formation of unsymmetric vesicles using the helix dipole, stereocomplex, and steric effects of peptides

Unsymmetrical vesicular membranes were prepared from a binary mixture of the A3B-type and the AB-type host polypeptides, which were composed of the hydrophilic block (A) and the hydrophobic helical block (B) but with a different helix sense between the two host polypeptides. TEM and DLS revealed the formation of vesicles with ca. 100 nm diameter. The molecular assembly was driven by hydrophobic interaction, stereocomplex formation, and dipole-dipole interaction between hydrophobic helices. Furthermore, the A3B-type host polypeptide extended the hydrophilic block to the outer surface of vesicles as a result of the steric effect, resulting in the formation of unsymmetrical vesicular membranes. As a result, a functionalized AB-type guest polypeptide having the same helix sense with the A3B-type host polypeptide exposed the hydrophilic block to the outer surface. In contrast, an AB-type guest polypeptide having the same helix sense with the AB-type host polypeptide oriented the hydrophilic block to the inner surface. Functionalization of either the outer or inner surface of the binary vesicle is therefore facile to achieve when using either the right- or the left-handed helix of the functionalized guest polypeptide.

Morphology control between twisted ribbon, helical ribbon, and nanotube self-assemblies with his-containing helical peptides in response to pH change

pH-Responsive molecular assemblies with a variation in morphology ranging from a twisted ribbon, a helical ribbon, to a nanotube were prepared from a novel A3B-type amphiphilic peptide having three hydrophilic poly(sarcosine) (A block) chains, a hydrophobic helical dodecapeptide (B block), and two histidine (His) residues between the A3 and B blocks. The A3B-type peptide adopted morphologies of the twisted ribbon at pH 3.0, the helical ribbon at pH 5.0, and the nanotube at pH 7.4, depending upon the protonation states of the two His residues. On the other hand, another A3B-type peptide having one His residue between the A3 and B blocks showed a morphology change only between the helical ribbon and the relatively planar sheets with pH variation in this range. The morphology change is thus induced by one- or two-charge generation at the linking site of the hydrophilic and hydrophobic blocks of the component amphiphiles but in different ways.

1D to 2D Na+ ion diffusion inherently linked to structural transitions in Na0.7CoO2

We report the observation of a stepwise "melting" of the low-temperature Na-vacancy order in the layered transition-metal oxide Na0.7CoO2. High-resolution neutron powder diffraction analysis indicates the existence of two first-order structural transitions, one at T1≈290  K followed by a second at T2≈400  K. Detailed analysis strongly suggests that both transitions are linked to changes in the Na mobility. Our data are consistent with a two-step disappearance of Na-vacancy order through the successive opening of first quasi-1D (T1>T>T2) and then 2D (T>T2) Na diffusion paths. These results shed new light on previous, seemingly incompatible, experimental interpretations regarding the relationship between Na-vacancy order and Na dynamics in this material. They also represent an important step towards the tuning of physical properties and the design of tailored functional materials through an improved control and understanding of ionic diffusion.

Proton-dependent coniferin transport, a common major transport event in differentiating xylem tissue of woody plants

Lignin biosynthesis is an essential physiological activity of vascular plants if they are to survive under various environmental stresses on land. The biosynthesis of lignin proceeds in the cell wall by polymerization of precursors; the initial step of lignin polymerization is the transportation of lignin monomers from the cytosol to the cell wall, which is critical for lignin formation. There has been much debate on the transported form of the lignin precursor, either as free monolignols or their glucosides. In this study, we performed biochemical analyses to characterize the membrane transport mechanism of lignin precursors using angiosperms, hybrid poplar (Populus sieboldii × Populus grandidentata) and poplar (Populus sieboldii), as well gymnosperms, Japanese cypress (Chamaecyparis obtusa) and pine (Pinus densiflora). Membrane vesicles prepared from differentiating xylem tissues showed clear ATP-dependent transport activity of coniferin, whereas less than 4% of the coniferin transport activity was seen for coniferyl alcohol. Bafilomycin A1 and proton gradient erasers markedly inhibited coniferin transport in hybrid poplar membrane vesicles; in contrast, vanadate had no effect. Cis-inhibition experiments suggested that this transport activity was specific for coniferin. Membrane fractionation of hybrid poplar microsomes demonstrated that transport activity was localized to the tonoplast- and endomembrane-rich fraction. Differentiating xylem of Japanese cypress exhibited almost identical transport properties, suggesting the involvement of a common endomembrane-associated proton/coniferin antiport mechanism in the lignifying tissues of woody plants, both angiosperms and gymnosperms.

Degradation and synthesis of β-glucans by a Magnaporthe oryzae endotransglucosylase, a member of the glycoside hydrolase 7 family

BACKGROUND

Plant pathogens secrete enzymes that degrade plant cell walls to enhance infection and nutrient acquisition.

RESULTS

A novel endotransglucosylase catalyzes cleavage and transfer of β-glucans and decreases the physical strength of plant cell walls.

CONCLUSION

Endotransglucosylation causes depolymerization and polymerization of β-glucans, depending on substrate molecular size.

SIGNIFICANCE

Enzymatic degradation of plant cell walls is required for wall loosening, which enhances pathogen invasion. A Magnaporthe oryzae enzyme, which was encoded by the Mocel7B gene, was predicted to act on 1,3-1,4-β-glucan degradation and transglycosylation reaction of cellotriose after partial purification from a culture filtrate of M. oryzae cells, followed by liquid chromatography-tandem mass spectrometry. A recombinant MoCel7B prepared by overexpression in M. oryzae exhibited endo-typical depolymerization of polysaccharides containing β-1,4-linkages, in which 1,3-1,4-β-glucan was the best substrate. When cellooligosaccharides were used as the substrate, the recombinant enzyme generated reaction products with both shorter and longer chain lengths than the substrate. In addition, incorporation of glucose and various oligosaccharides including sulforhodamine-conjugated cellobiose, laminarioligosaccharides, gentiobiose, xylobiose, mannobiose, and xyloglucan nonasaccharide into β-1,4-linked glucans were observed after incubation with the enzyme. These results indicate that the recombinant enzyme acts as an endotransglucosylase (ETG) that cleaves the glycosidic bond of β-1,4-glucan as a donor substrate and transfers the cleaved glucan chain to another molecule functioning as an acceptor substrate. Furthermore, ETG treatment caused greater extension of heat-treated wheat coleoptiles. The result suggests that ETG functions to induce wall loosening by cleaving the 1,3-1,4-β-glucan tethers of plant cell walls. On the other hand, use of cellohexaose as a substrate for ETG resulted in the production of cellulose II with a maximum length (degree of polymerization) of 26 glucose units. Thus, ETG functions to depolymerize and polymerize β-glucans, depending on the size of the acceptor substrate.

Self-assemblies of triskelion A2B-type amphiphilic polypeptide showing pH-responsive morphology transformation

A pH-responsive rolled-sheet morphology was prepared from a triskelion A(2)B-type amphiphilic polypeptide having a histidine residue as a pH-responsive unit. The dimensions of the rolled sheet were 85 nm diameter and 210 nm length with a sheet turn number of 2.0 at pH 7.4. Upon decreasing the pH from 7.4 to 5.0, the layer spacing of the rolled sheets was widened from ca. 9 to ca. 19 nm due to electrostatic repulsion caused by histidine protonation. This morphology change occurred reversibly with a pH change between 7.4 and 5.0. The molecular packing in the rolled sheets was shown to be loosened at pH 5.0 on the basis of electron diffraction measurements. The tightness of the rolled sheets was thus controlled reversibly by a pH change due to a single protonation in the amphiphilic polypeptide.

Chemometric analysis with near-infrared spectroscopy for chemically pretreated Erianthus toward efficient bioethanol production

In this paper, we report the combination of a near-infrared (NIR) spectroscopic method with multivariate analysis in order to develop a calibration model of the saccharification ratio of chemically pretreated Erianthus. The regression models clearly depend on the NIR spectral regions, and the information of CH and aromatic framework vibrations contributed most effectively to the alkaline dataset. From interpretations of the regression coefficient, lignin and cellulose were negatively and positively correlated with the saccharification ratio, respectively, and this result was supported by the data from wet chemical analysis. A more complex dataset was obtained from varied chemical pretreatments; here, the saccharification ratio was either small or had no linear correlation with each structural monocomponent. These results enabled the successful construction of the PLS regression model. NIR spectroscopy can be a rapid screening method for the saccharification ratio, and furthermore, can provide information of the key factors influencing the realization of more efficient enzymatic accessibility.

Extraction of cellulose-synthesizing activity of Gluconacetobacter xylinus by alkylmaltoside

This study reinvestigated the synthesis of cellulose in vitro with a well-known cellulose-producing bacterium, Gluconacetobacter xylinus. Alkylmaltoside detergents, which are more frequently used in recent structural biological researches, are uniquely used in this study to solubilize cellulose-synthesizing activity from the cell membrane of G. xylinus. Activity comparable to that previously reported is obtained, while the synthesized cellulose is crystallized into a non-native polymorph of cellulose (cellulose II) as well as the previous studies. In spite of this failure to recover the native activity to synthesize cellulose I microfibril in vitro, the product is a polymer with a degree of polymerization greater than 45 as determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). It was thus concluded that the established protocol can solubilize cellulose-synthesizing activity of G. xylinus with polymerizing activity.

Preparation of fibrous cellulose by enzymatic polymerization using cross-linked mutant endoglucanase II

A cross-linked mutant endoglucanase II was prepared for enzymatic polymerization to cellulose. The cross-linked enzyme is composed of three mutant enzymes showing polymerization activity. A characteristic feature of the polymerization with this cross-linked enzyme is formation of cellulose fibrils in contrast to plate-like crystals obtained by using a free enzyme.

Temperature-triggered fusion of vesicles composed of right-handed and left-handed amphiphilic helical peptides

Vesicles prepared from a mixture of (Sar)(25)-b-(L-Leu-Aib)(6) (SLL) and (Sar)(25)-b-(D-Leu-Aib)(6) (SDL) fused with themselves upon heating to 90 °C. The vesicles also fused with (Sar)(28)-b-(L-Leu-Aib)(8) vesicles upon heating to 90 °C. The temperature-triggered fusion was due to the phase transition of the mixed membrane of SLL and SDL at 90 °C and should be driven by the bending energy stored in the stereocomplex membrane upon taking a vesicular structure.

Ectopic expression of cone-specific G-protein-coupled receptor kinase GRK7 in zebrafish rods leads to lower photosensitivity and altered responses

To investigate the roles of G-protein receptor kinases (GRKs) in the light responses of vertebrate photoreceptors, we generated transgenic zebrafish lines, the rods of which express either cone GRK (GRK7) or rod GRK (GRK1) in addition to the endogenous GRK1, and we then measured the electrophysiological characteristics of single-cell responses and the behavioural responses of intact animals. Our study establishes the zebrafish expression system as a convenient platform for the investigation of specific components of the phototransduction cascade. The addition of GRK1 led to minor changes in rod responses. However, exogenous GRK7 in GRK7-tg animals led to lowered rod sensitivity, as occurs in cones, but surprisingly to slower response kinetics. Examination of responses to long series of very dim flashes suggested the possibility that the GRK7-tg rods generated two classes of single-photon response, perhaps corresponding to the interaction of activated rhodopsin with GRK1 (giving a standard response) or with GRK7(giving a very small response). Behavioural measurement of optokinetic responses (OKR) in intact GRK7-tg zebrafish larvae showed that the overall rod visual pathway was less sensitive, in accord with the lowered sensitivity of the rods. These results help provide an understanding for the molecular basis of the electrophysiological differences between cones and rods.