The alpha7 nicotinic acetylcholine receptor: molecular modelling, electrostatics, and energetics

The structure of a homopentameric alpha7 nicotinic acetylcholine receptor is modelled by combining structural information from two sources: the X-ray structure of a water soluble acetylcholine binding protein from Lymnea stagnalis, and the electron microscopy derived structure of the transmembrane domain of the Torpedo nicotinic receptor. The alpha7 nicotinic receptor model is generated by simultaneously optimising: (i) chain connectivity, (ii) avoidance of stereochemically unfavourable contacts, and (iii) contact between the beta1-beta2 and M2-M3 loops that have been suggested to be involved in transmission of conformational change between the extracellular and transmembrane domains. A Gaussian network model was used to predict patterns of residue mobility in the alpha7 model. The results of these calculations suggested a flexibility gradient along the transmembrane domain, with the extracellular end of the domain more flexible that the intracellular end. Poisson-Boltzmann (PB) energy calculations and atomistic (molecular dynamics) simulations were used to estimate the free energy profile of a Na+ ion as a function of position along the axis of the pore-lining M2 helix bundle of the transmembrane domain. Both types of calculation suggested a significant energy barrier to exist in the centre of the (closed) pore, consistent with a "hydrophobic gating" model. Estimations of the PB energy profile as a function of ionic strength suggest a role of the extracellular domain in determining the cation selectivity of the alpha7 nicotinic receptor. These studies illustrate how molecular models of members of the nicotinic receptor superfamily of channels may be used to study structure-function relationships.     

New Species of Spirotrichonympha from Reticulitermes and the Relationships Among Genera in Spirotrichonymphea (Parabasalia)

Spirotrichonymphea is a class of hypermastigote parabasalids defined by their spiral rows of many flagella. They are obligate hindgut symbionts of lower termites. Despite more than 100 yr of morphological and ultrastructural study, the group remains poorly characterised by molecular data and the phylogenetic positions and taxonomic validity of most genera remain in question. The genus Spirotrichonympha has been reported to inhabit several termite genera, including Reticulitermes, Coptotermes, and Hodotermopsis. The type species for this genus, Spirotrichonympha flagellata, was described from Reticulitermes lucifugus but no molecular data are yet available for this species. In this study, three new Spirotrichonympha species are described from three species of Reticulitermes. Their molecular phylogenetic position indicates that the genus is not monophyletic, as Spirotrichonympha species from Coptotermes, Paraneotermes, and Hodotermopsis branch separately. In contrast, the genus Holomastigotoides is monophyletic, as demonstrated using new sequences from Holomastigotoides species. The presence of Holomastigotoides in Prorhinotermes and the distinct phylogenetic positions of Spirotrichonympha from Reticulitermes and Coptotermes are consistent with a previously proposed symbiont fauna replacement in the ancestor of Reticulitermes.     

Holey 2D Nanomaterials for Electrochemical Energy Storage

2D nanomaterials provide numerous fascinating properties, such as abundant active surfaces and open ion diffusion channels, which enable fast transport and storage of lithium ions and beyond. However, decreased active surfaces, prolonged ion transport pathway, and sluggish ion transport kinetics caused by self‐restacking of 2D nanomaterials during electrode assembly remain a major challenge to build high‐performance energy storage devices with simultaneously maximized energy and power density as well as long cycle life. To address the above challenge, porosity (or hole) engineering in 2D nanomaterials has become a promising strategy to enable porous 2D nanomaterials with synergetic features combining both 2D nanomaterials and porous architectures. Herein, recent important progress on porous/holey 2D nanomaterials for electrochemical energy storage is reviewed, starting with the introduction of synthetic strategies of porous/holey 2D nanomaterials, followed by critical discussion of design rule and their advantageous features. Thereafter, representative work on porous/holey 2D nanomaterials for electrochemical capacitors, lithium‐ion and sodium‐ion batteries, and other emerging battery technologies (lithium‐sulfur and metal‐air batteries) are presented. The article concludes with perspectives on the future directions for porous/holey 2D nanomaterial in energy storage and conversion applications.     

PET-based Treatment Response Assessment for Neoadjuvant Chemoradiation in Pancreatic Adenocarcinoma: An Exploratory Study

PURPOSE: Performance of anatomical metrics of Response Evaluation Criteria in Solid Tumors (RECIST1.1) versus Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST1.0) for neoadjuvant chemoradiation (nCR) of pancreatic adenocarcinoma was evaluated based on the pathological treatment response (PTR) data. METHODS AND MATERIALS: The pre- and post-nCR CT and PET data for 14 patients with resectable or borderline resectable pancreatic head adenocarcinoma treated with nCR followed by surgery were retrospectively analyzed. These data were compared with the PTR which were graded according to tumor cell destruction (cellularity), with Grade 0, 1, 2 or 3 (G0, G1, G2 or G3) for complete, moderate, minimal and poor responses, respectively. Maximum standardized uptake value (SUVmax) was defined using body-weight (SUVbw). PERCIST1.0 was defined using lean-body mass normalized SUV (SUVlb or SUL). RECIST1.1 was defined by contouring the whole pancreas head on the CT image. Pre- and post-SUL-peak and SUVmax, RECIST1.1 and PETRECIST1.0 were correlated with PTR using Pearson’s correlation coefficient test. RESULTS: The average mean and SD in SUL-peak for all patients analyzed were lower in post-nCR (3.63±1.06) compared to those at pre-nCR (4.29±0.89). Using PERCIST1.0, 62% of patients showed stable metabolic disease (SMD), 23% partial metabolic response (PMR), and 15% progressive metabolic disease (PMD). Using RECIST1.1, 85% of patients showed stable disease (SD), 8% partial response (PR), and 7% progressive diseases (PD). A poor insignificant correlation was established between PRT and PERECIST1.0 (r=0.121), whereas no correlation was seen with RECIST1.1. CONCLUSIONS: PERCIST1.0 appears to increase the chance of detecting patients with progressive disease compared to the conventional anatomical-based assessment of RECIST1.1. The integration of these additional radiographic metrics in assessing treatment response to nCR for pancreatic adenocarcinoma may provide a promising strategy to better select patients that are most suitable for therapeutic intensification.     

Ganglioside composition of the rat choriocarcinoma cell line,Rcho-1

The Rcho-1 cell line, originally established from a rat choriocarcinoma, shows differentiation into placental trophoblastic giant cell-like cells and has been used to study the mechanism of placental function control. In the present study, we analysed the ganglioside composition of Rcho-1 cells by HPTLC orcinol/H₂SO₄, TLC/immunostaining and immunohistochemistry. Rcho-1 cells expressed GM3 and GD3 as the major gangliosides and CTH as major neutral glycolipid when they were cultured in growth medium (20% FCS) or transplanted beneath the kidney capsule. The expression of these gangliosides was strong in the undifferentiated small cells, whereas the completely differentiated giant cells showed poor staining with antibodies against the gangliosides. Under culture conditions to induce cell differentiation using horse serum (1–20% HS), the expression of GD3 was suppressed and re-expressed when the medium was changed to growth medium, suggesting that a change of ganglioside components may trigger and define the direction of terminal differentiation. Thus the composition of glycolipids is conserved in Rcho-1 cells and is similar to that of the rat placenta, where GM3 is dominant in mid-pregnancy and decreased in late pregnancy, whereas GD3 is low in mid-pregnancy and increased in late pregnancy.     

Interactions of dedicated export membrane proteins of the colicin V secretion system: CvaA, a member of the membrane fusion protein family, interacts with CvaB and TolC.

The antibacterial peptide toxin colicin V uses a dedicated signal sequence-independent system for its secretion in Escherichia coli and requires the products of three genes, cvaA, cvaB, and tolC. As a member of the membrane fusion protein family, CvaA is supposed to form a bridge that connects the inner and outer membranes via interaction with CvaB and TolC, respectively. In this study, we investigated the possible interaction of these proteins. When CvaA or CvaB was absent, the corresponding amount of CvaB or CvaA, respectively, was decreased, and the amounts of both proteins were reduced when TolC was depleted. Translational lacZ fusions showed that TolC did not affect the synthesis of either CvaA-beta-galactosidase or CvaB-beta-galactosidase, and CvaA or CvaB did not affect the synthesis of CvaB-beta-galactosidase or CvaA-beta-galactosidase, respectively. However, the stabilities of CvaA and CvaB proteins were affected by the absence of one another and by that of TolC. The instability of CvaA was more severe in TolC-depleted cells than in CvaB-depleted cells. On the other hand, CvaB was less stable in the absence of CvaA than in the absence of TolC. In addition, using a cross-linking reagent, we showed that CvaA directly interacts with both CvaB and TolC proteins. Taken together, these data support the hypothesized structural role of CvaA in connecting CvaB and TolC.     

Identification of Three Novel Unique Proteins in Seed Oil Bodies of Sesame

Graduate Institute of Agricultural Biotechnology, National Chung-HsingUniversity, Taichung, Taiwan 40227, ROC Plant seeds store triacylglycerolsin discrete organelles called oil bodies. An oil body preservesa matrix of triacylglycerols surrounded by a monolayer of phospholipidsembedded with abundant structural proteins termed oleosins andprobably some uninvestigated minor proteins of higher molecularmass. Three polypeptides of 27, 37, and 39 kDa (temporarilydenominated as Sopl, Sop2, and Sop3) were regularly co-purifiedwith seed oil bodies of sesame. Comparison of amino acid compositionindicated that they were substantially less hydrophobic thanthe known oleosins, and thus should not be aggregated multimersof oleosins. The results of immuno-recognition to sesame proteinsextracted from subcellular fractions of mature seeds, varioustissues, and oil bodies purified from different stages of seedformation revealed that these three polypeptides were uniqueproteins gathered in oil bodies, accompanying oleosins and triacylglycerols,during the active assembly of the organelles in maturing seeds.Both in vivo and in intro, immunofluorescence labeling usingsecondary antibodies conjugated with FITC (fluorescein isothiocyanate)confirmed the localization of these three polypeptides in oilbodies. ¹To whom correspondence should be addressed