Protein design to understand peptide ligand recognition by tetratricopeptide repeat proteins

Protein design aims to understand the fundamentals of protein structure by creating novel proteins with pre-specified folds. An equally important goal is to understand protein function by creating novel proteins with pre-specified activities. Here we describe the design and characterization of a tetratricopeptide (TPR) protein, which binds to the C-terminal peptide of the eukaryotic chaperone Hsp90. The design emphasizes the importance of both direct, short-range protein-peptide interactions and of long-range electrostatic optimization. We demonstrate that the designed protein binds specifically to the desired peptide and discriminates between it and the similar C-terminal peptide of Hsp70.     

Suitability of Sodium Pyruvate as Decomposer of Carried-over Liquid Hydrogen Peroxide

The aim of the present study was to evaluate the concentration of sodium pyruvate in growth media by using the most-probable number method to decompose carried-over liquid hydrogen peroxide (H₂O₂) without negative influences on correct enumeration of Geobacillus stearothermophilus spores. An equivalent molar ratio of sodium pyruvate and H₂O₂ was verified to be sufficient for a complete decomposition. The results showed that by exposition of G. stearothermophilus spores in different liquid hydrogen peroxide and by carry-over of concentrations ranging from 3.56 · 10⁻⁶ up to 1.69 · 10⁻⁴ mol, a sodium pyruvate concentration of 0.05 mol L⁻¹ in growth media was most efficient for the recovery of spores.     

Bulk Sediment and Diatom Silica Carbon Isotope Composition from Coastal Marine Sediments off East Antarctica

Organic carbon occluded in diatom silica is assumed to be protected from degradation in the sediment. δ¹³C from diatom carbon (δ¹³C_(diatom)) therefore potentially provides a signal of conditions during diatom growth. However, there have been few studies based on δ¹³C_(diatom). Numerous variables can influence δ¹³C of organic matter in the marine environment (e.g., salinity, light, nutrient and CO₂ availability). Here we compare δ¹³C_(diatom) and δ¹³C_(TOC) from three sediment records from individual marine inlets (Rauer Group, East Antarctica) to (i) investigate deviations between δ¹³C_(diatom) and δ¹³C_(TOC), to (ii) identify biological and environmental controls on δ¹³C_(diatom) and δ¹³C_(TOC), and to (iii) discuss δ¹³C_(diatom) as a proxy for environmental and climate reconstructions. The records show individual δ¹³C_(diatom) and δ¹³C_(TOC) characteristics, which indicates that δ¹³C is not primarily controlled by regional climate or atmospheric CO₂ concentration. Since the inlets vary in water depths offsets in δ¹³C are probably related to differences in water column stratification and mixing, which influences redistribution of nutrients and carbon within each inlet. In our dataset changes in δ¹³C_(diatom) and δ¹³C_(TOC) could not unequivocally be ascribed to changes in diatom species composition, either because the variation in δ¹³C_(diatom) between the observed species is too small or because other environmental controls are more dominant. Records from the Southern Ocean show depleted δ¹³C_(diatom) values (1–4 ‰) during glacial times compared to the Holocene. Although climate variability throughout the Holocene is low compared to glacial/interglacial variability, we find variability in δ¹³C_(diatom), which is in the same order of magnitude. δ¹³C of organic matter produced in the costal marine environment seems to be much more sensitive to environmental changes than open ocean sites and δ¹³C is of strongly local nature.     

A Micro-manipulation Technique for the Purification of Diatoms for Isotope and Geochemical Analysis

A method is described for the purification and extraction of diatom samples for isotope and geochemical analysis. The technique involves a micro-manipulator attached to an inverted microscope with a cellular micro-injector system used to remove contaminants or separate assemblages into single-species samples. Whilst time consuming, the advances associated with this technique, eliminating issues related to contamination and the impact of species-dependent fractionation factor/isotopic effect, allows ultra-clean as well as species and/or size specific diatom samples to be analysed in palaeoenvironmental research down to seasonal timescale resolution. By further altering the inner dimensions of the commercially available capillary tubes, (3.5–150  $\upmu $ m) this technique can be extended for use with other microfossils including radiolaria (30  $\upmu $ m to 1 mm), pollen (6–100  $\upmu $ m) and phytolith samples (1–200  $\upmu $ m).     

Circular RNAs in Pregnancy and the Placenta

The emerging field of circular RNAs (circRNAs) has identified their novel roles in the development and function of many cancers and inspired the interest of many researchers. circRNAs are also found throughout the healthy body, as well as in other pathological states, but while research into the function and abundance of circRNAs has progressed, our overall understanding of these molecules remains primitive. Importantly, recent studies are elucidating new roles for circRNAs in pregnancy, particularly in the placenta. Given that many of the genes responsible for circRNA production in cancer are also highly expressed in the placenta, it is likely that the same genes act in the production of circRNAs in the placenta. Furthermore, placental development can be referred to as ‘controlled cancer’, as it shares many key signalling pathways and hallmarks with tumour growth and metastasis. Hence, the roles of circRNAs in this field are important to study with respect to pregnancy success but also may provide novel insights for cancer progression. This review illuminates the known roles of circRNAs in pregnancy and the placenta, as well as demonstrating differential placental expressions of circRNAs between complicated and uncomplicated pregnancies.     

Determination of hemin-binding characteristics of proteins by a combinatorial peptide library approach

Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron‐ion‐containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate‐covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)₄(C/H/Y)(X)₄ to characterize peptide ligands with considerable hemin binding capacities. Some of the library‐selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His‐based (≈39 %) and Tyr‐based (≈40 %) sequences over Cys‐based ones (≈21 %) was detected. The binding affinities for the library‐selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme‐binding domain.     

洗衣剂的发展趋势（英）

新用途和多功能产品使洗衣剂除了清洗衣物外,有了更大作用,分析了液体洗涤剂和粉状洗涤剂的市场,正确评估了片状洗涤剂的市场前景,指出,省时和多功能将是洗衣剂未来发展的趋势。     

Processing and properties of syntactic foams reinforced with carbon nanotubes

This article presents synthesis and mechanical characterization of carbon nanotube (CNT)‐reinforced syntactic foams. Following a dispersion approach (comprising ultrasonic, calendering, and vacuum centrifugal mixing), single‐ and multi‐walled functionalized CNTs (FCNTs) were incorporated into two foam composites containing various commercially available microballoon grades (S38HS, S60HS, and H50 from 3M). The FCNT‐reinforced composites were tested for compressive strength and apparent shear strength before and after hot/wet conditioning. The results showed that the FCNT‐reinforced composites' mechanical properties depended on the vacuum pressure used during processing. Compared with pristine and commercially available syntactic foam (EC‐3500 from 3M), the FCNT‐reinforced composites processed at high vacuum (0.2 kPa) showed significant increase in compressive strength and apparent shear strength before and after hot/wet conditioning. Dynamic mechanical analysis showed an increase of about 22°C in glass transition temperature for composites processed at high vacuum with 0.5 wt % FCNT and 45 wt % S38HS–5 wt % S60HS microballoons. Thermogravimetric analysis indicated water absorption and lower decomposition temperature for the FCNT‐reinforced composite mixed at atmospheric pressure, whereas no significant change was observed for the compound processed at high vacuum. Fracture analysis showed matrix failure for the composite processed at high vacuum and microballoon crushing for the composite mixed at atmospheric pressure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Intergenerational Metabolomic Analysis of Mothers with a History of Gestational Diabetes Mellitus and Their Offspring

Shared metabolomic patterns at delivery have been suggested to underlie the mother-to-child transmission of adverse metabolic health. This study aimed to investigate whether mothers with gestational diabetes mellitus (GDM) and their offspring show similar metabolomic patterns several years postpartum. Targeted metabolomics (including 137 metabolites) was performed in plasma samples obtained during an oral glucose tolerance test from 48 mothers with GDM and their offspring at a cross-sectional study visit 8 years after delivery. Partial Pearson’s correlations between the area under the curve (AUC) of maternal and offspring metabolites were calculated, yielding so-called Gaussian graphical models. Spearman’s correlations were applied to investigate correlations of body mass index (BMI), Matsuda insulin sensitivity index (ISI-M), dietary intake, and physical activity between generations, and correlations of metabolite AUCs with lifestyle variables. This study revealed that BMI, ISI-M, and the AUC of six metabolites (carnitine, taurine, proline, SM(-OH) C14:1, creatinine, and PC ae C34:3) were significantly correlated between mothers and offspring several years postpartum. Intergenerational metabolite correlations were independent of shared BMI, ISI-M, age, sex, and all other metabolites. Furthermore, creatinine was correlated with physical activity in mothers. This study suggests that there is long-term metabolic programming in the offspring of mothers with GDM and informs us about targets that could be addressed by future intervention studies.     

Sorbent injection into a slipstream baghouse for mercury control: Project summary

A project led by the Energy and Environmental Research Center to test and demonstrate sorbent injection as a cost-effective mercury control technology for utilities burning lignites has shown effective mercury capture under a range of operating conditions. Screening, parametric, and long-term tests were carried out at a slipstream facility representing an electrostatic precipitator–activated carbon injection–fabric filter configuration (called a TOXECON™ in the United States). Screening tests of sorbent injection evaluated nine different sorbents, including both treated and standard activated carbon, to compare mercury capture as a function of sorbent injection rate. Parametric tests evaluated several variables including air-to-cloth (A/C) ratio, flue gas temperature, cleaning frequency, and dust loading to determine the effect on mercury control and systems operation. Long-term tests (approximately 2 months in duration) evaluated the sustainability of systems operation.