The analysis of merino wool cuticle and cortical cells by Fourier transform Raman spectroscopy

Wool fibers are comprised of proteins known as α-keratins and have a complex morphological structure. The major components of this structure, the cuticle and cortical cells, differ in the conformations of their peptide chains as well as their amino acid compositions. High quality Fourier transform Raman spectra of cortical and cuticle cells isolated from fine Merino wool fibers have been obtained. Raman spectroscopy has been shown to be sensitive to the differences in both secondary structure and amino acid composition. The cortical cells were found to be higher in α-helical content as compared to the cuticle cells, which had an increased disordered content. Specific information, consistent with amino acid analysis results, regarding cystine, tyrosine, tryptophan, and phenylalanine residues, were obtained for both the cortical and cuticle cells. In addition, the Raman spectra provided information about free thiol groups, amino acids residues with amide group side chains, and residues with protonated carboxyl group side chains. Middle ir transmission spectra of these isolated cells were also obtained. In comparison to the Raman data, the middle ir spectra were found to be not as rich in information. © 1997 John Wiley & Sons, Inc. Biopoly 42: 7–17, 1997     

Investigating the structural dynamics of the PIEZO1 channel activation and inactivation by coarse‐grained modeling

The PIEZO channels, a family of mechanosensitive channels in vertebrates, feature a fast activation by mechanical stimuli (eg, membrane tension) followed by a slower inactivation. Although a medium‐resolution structure of the trimeric form of PIEZO1 was solved by cryo‐electron microscopy (cryo‐EM), key structural changes responsible for the channel activation and inactivation are still unknown. Toward decrypting the structural mechanism of the PIEZO1 activation and inactivation, we performed systematic coarse‐grained modeling using an elastic network model and related modeling/analysis tools (ie, normal mode analysis, flexibility and hotspot analysis, correlation analysis, and cryo‐EM‐based hybrid modeling and flexible fitting). We identified four key motional modes that may drive the tension‐induced activation and inactivation, with fast and slow relaxation time, respectively. These modes allosterically couple the lateral and vertical motions of the peripheral domains to the opening and closing of the intra‐cellular vestibule, enabling external mechanical forces to trigger, and regulate the activation/inactivation transitions. We also calculated domain‐specific flexibility profiles, and predicted hotspot residues at key domain‐domain interfaces and hinges. Our results offer unprecedented structural and dynamic information, which is consistent with the literature on mutational and functional studies of the PIEZO channels, and will guide future studies of this important family of mechanosensitive channels.     

Altered dynamics upon oligomerization corresponds to key functional sites

It is known that over half of the proteins encoded by most organisms function as oligomeric complexes. Oligomerization confers structural stability and dynamics changes in proteins. We investigate the effects of oligomerization on protein dynamics and its functional significance for a set of 145 multimeric proteins. Using coarse‐grained elastic network models, we inspect the changes in residue fluctuations upon oligomerization and then compare with residue conservation scores to identify the functional significance of these changes. Our study reveals conservation of about ½ of the fluctuations, with ¼ of the residues increasing in their mobilities and ¼ having reduced fluctuations. The residues with dampened fluctuations are evolutionarily more conserved and can serve as orthosteric binding sites, indicating their importance. We also use triosephosphate isomerase as a test case to understand why certain enzymes function only in their oligomeric forms despite the monomer including all required catalytic residues. To this end, we compare the residue communities (groups of residues which are highly correlated in their fluctuations) in the monomeric and dimeric forms of the enzyme. We observe significant changes to the dynamical community architecture of the catalytic core of this enzyme. This relates to its functional mechanism and is seen only in the oligomeric form of the protein, answering why proteins are oligomeric structures. Proteins 2017; 85:1422–1434. © 2017 Wiley Periodicals, Inc.     

MoS2‐Based All‐Purpose Fibrous Electrode and Self‐Powering Energy Fiber for Efficient Energy Harvesting and Storage

Here an all‐purpose fibrous electrode based on MoS₂ is demonstrated, which can be employed for versatile energy harvesting and storage applications. In this coaxial electrode, ultrathin MoS₂ nanofilms are grown on TiO₂ nanoparticles coated carbon fiber. The high electrochemical activity of MoS₂ and good conductivity of carbon fiber synergistically lead to the remarkable performances of this novel composite electrode in fibrous dye‐sensitized solar cells (showing a record‐breaking conversion efficiency of 9.5%) and high‐capacity fibrous supercapacitors. Furthermore, a self‐powering energy fiber is fabricated by combining a fibrous dye‐sensitized solar cell and a fibrous supercapacitor into a single device, showing very fast charging capability (charging in 7 s under AM1.5G solar illumination) and an overall photochemical‐electricity energy conversion efficiency as high as 1.8%. In addition, this wire‐shaped electrode can also be used for fibrous Li‐ion batteries and electrocatalytic hydrogen evolution reactions. These applications indicate that the MoS₂‐based all‐purpose fibrous electrode has great potential for the construction of high‐performance flexible and wearable energy devices.     

Deregulation of focal adhesion formation and cytoskeletal tension due to loss of A-type lamins

The nuclear lamina mechanically integrates the nucleus with the cytoskeleton and extracellular environment and regulates gene expression. These functions are exerted through direct and indirect interactions with the lamina's major constituent proteins, the A-type lamins, which are encoded by the LMNA gene. Using quantitative stable isotope labeling-based shotgun proteomics we have analyzed the proteome of human dermal fibroblasts in which we have depleted A-type lamins by means of a sustained siRNA-mediated LMNA knockdown. Gene ontology analysis revealed that the largest fraction of differentially produced proteins was involved in actin cytoskeleton organization, in particular proteins involved in focal adhesion dynamics, such as actin-related protein 2 and 3 (ACTR2/3), subunits of the ARP2/3 complex, and fascin actin-bundling protein 1 (FSCN1). Functional validation using quantitative immunofluorescence showed a significant reduction in the size of focal adhesion points in A-type lamin depleted cells, which correlated with a reduction in early cell adhesion capacity and an increased cell motility. At the same time, loss of A-type lamins led to more pronounced stress fibers and higher traction forces. This phenotype could not be mimicked or reversed by experimental modulation of the STAT3-IL6 pathway, but it was partly recapitulated by chemical inhibition of the ARP2/3 complex. Thus, our data suggest that the loss of A-type lamins perturbs the balance between focal adhesions and cytoskeletal tension. This imbalance may contribute to mechanosensing defects observed in certain laminopathies.     

Thermodynamics of ABC transporters

ABC transporters form the largest of all transporter families, and their structural study has made tremendous progress over recent years. However, despite such advances, the precise mechanisms that determine the energy-coupling between ATP hydrolysis and the conformational changes following substrate binding remain to be elucidated. Here, we present our thermodynamic analysis for both ABC importers and exporters, and introduce the two new concepts of differential-binding energy and elastic conformational energy into the discussion.We hope that the structural analysis of ABC transporters will henceforth take thermodynamic aspects of transport mechanisms into account as well.     

Prokaryotic microbiota of recycled paper mills with low or zero effluent

The tendency in the paper industry is to close all water loops to save water. This leads to higher process temperatures and may increase the colloidal and dissolved material in the process circulation. Increase of nutrients in the water circuits may favor microbiological growth and fouling. In this paper the chemical and microbial compositions of water circuits and deposits were studied of two closed cycled paper/board mills, one mill totally closed (0 m(3) waste water t(-1)), and the other low discharging (about 4 m(3 )t(-1)). The zero discharge mill accumulated high amounts (>10 g C L(-1)) of organic carbon in the circulation waters, about 40% of which composed of volatile acids (lactic, acetic, propionic and butyric acid). Water contents of sulfate, chloride, sodium and calcium increased to >1 g L(-1) of each. q-PCR targeted on 16S rRNA genes indicated that the bacteria in water circuits were mainly viable cells. In both mills anaerobic growth (10(6)-10(8) CFU mL(-1)) equalled or exceeded aerobic growth, with odor problem but no actual slime problem. The major part (40%) of all identifiable bacterial sequences were closest but yet distant (<96%) to Enterococcus cecorum and in the 4 m(3 )t(-1) discharging mill also Bacillus thermoamylovorans and Bacillus coagulans. Slimes and deposits from the mills contained high amounts, >/=10(8) g(-1), of archaean, but only the genus Methanothrix was identifiable from the cloned sequences. The findings indicate that closing the water circuits strongly limited diversity of the microbiota but allowed efficient mineralization of the dissolved and suspended matter.     

Preparation and properties of starch acetate fibers for potential tissue engineering applications

This article reports the development of fibers from starch acetates that have mechanical properties and water stability better than most polysaccharide‐based biomaterials and protein fibers used in tissue engineering. In this research, starch acetates with three different degrees of substitution (DS) have been used to develop fibers for potential use as tissue engineering scaffolds. Varying the DS of starch acetate will provide fibers with different mechanical properties, hydrophilicity, and degradation behavior. Fibers made from DS 2.3 and 2.8 starch acetates have mechanical properties and water stability required for tissue engineering applications. The starch acetate fibers support the adhesion of fibroblasts demonstrating that the fibers would be suitable for tissue engineering and other medical applications. Biotechnol. Bioeng. 2009;103: 1016–1022. © 2009 Wiley Periodicals, Inc.     

Calbindin D-28k Immunoreactivity and Its Protein Level in Hippocampal Subregions During Normal Aging in Gerbils

The hippocampus is associated with learning and memory function and shows neurochemical changes in aging processes. Calbindin D-28k (CB) binds calcium ion with a fast association rate. We examined age-related changes in CB immunoreactivity and its protein level in the gerbil hippocampus during normal aging. In the hippocampal CA1 region (CA1) and CA2, CB immunoreaction was found in some neurons in the stratum pyramidale (SP) at postnatal month 1 (PM 1). CB immunoreactivity in neurons was markedly increased at PM 3. Thereafter, CB immunoreactivity was decreased with time: CB-immunoreactive (⁺) neurons were fewest at PM 24. In the CA3, a few CB⁺ neurons were found only in the SP at PM 1 and in the stratum radiatum at PM 18 and 24. In addition, mossy fibers were stained with CB at PM 1. CB immunoreactivity in mossy fibers was markedly increased at PM 3, thereafter it was decreased with time. In the dentate gyrus, many granule cells (GC) in the granule cell layer were stained with CB at PM 1. CB immunoreactivity in GC was markedly increased at PM 3, thereafter CB immunoreactivity was decreased with time. In Western blot analysis, CB protein level in the gerbil hippocampus was highest at PM 3, thereafter CB protein levels were decreased with time. This result indicates that CB in the gerbil hippocampus is abundant at PM 3 and is decreased with age.     

Physiological responses of different olive genotypes to drought conditions

Gas exchange rates, chlorophyll fluorescence, pressure–volume relationships, photosynthetic pigments, total soluble sugars, starch, soluble proteins and proline concentrations were investigated in five Olea europaea L. cultivars with different geographical origins (Arbequina, Blanqueta, Cobran?osa, Manzanilla and Negrinha) grown under Mediterranean field conditions. We found considerable genotypic differences among the cultivars. Comparing the diurnal gas exchange rates, we observed that Cobran?osa, Manzanilla and Negrinha had high photosynthetic rate than Arbequina and Blanqueta. The first group reveals to be better acclimated to drought conditions, and appears to employ a prodigal water-use strategy, whereas Blanqueta and Arbequina, with high water-use efficiency, appear to employ a conservative water-use strategy. The degree of midday depression in photosynthesis was genotype dependent, with a maximum in Arbequina and a minimum in Negrinha. The reductions in the photosynthetic rate were dependent from both stomatal and non-stomatal limitations. Elastic adjustment plays an important role as drought tolerance mechanism. The group of cultivars that employ a prodigal water-use strategy revealed high tissue elasticity, whereas Arbequina and Blanqueta revealed high tissue rigidity. We also identified the existence of drought tolerance mechanisms associated with soluble proteins accumulation in the foliage. The high levels of soluble proteins in Arbequina may represent an increased activity of oxidative stress defence enzymes and may also represent a reserve for post stress recovery. In all cultivars, especially in Manzanilla, free proline was accumulated in the foliage. The discussed aspects of drought stress metabolism may have an adaptative meaning, supporting the hypothesis that olive cultivars native to dry regions, such as Cobran?osa, Manzanilla and Negrinha, have more capability to acclimate to drought conditions than cultivars originated in regions with a more temperate climate, like Arbequina and Blanqueta.