A single amino acid in RTEL1 determines telomere length in mice

Maintaining optimal telomere length throughout life limits cancer and enables healthy aging. Yet, it is unclear how the telomere length set point is determined. Telomeres in the house mouse, Mus musculus, are 2-4 times longer than human telomeres, limiting the use of the mouse as a model for telomere research. By introducing a single amino acid variation found in M. spretus into the helicase RTEL1 of M. musculus, we shortened its telomere length set point 2-3 times, implicating this variation in the dramatic difference in telomere length between the two mouse species. While the engineered mice are fertile and healthy, hepatocytes with short telomeres displayed reduced proliferation capacity. This 'telomouse' is a unique model for studying the implications of short telomeres in aging and cancer.

Using biopolymers to strengthen the historical printed paper: mechanical and optical characters

Purpose This study aims to restore the lost mechanical properties of the prints with carrageenan, methyl hydroxyethyl cellulose (Tylose) and hydroxypropyl methylcellulose (Methocel). Design/methodology/approach The effect of these materials on the properties of the printed paper (modern and historical samples) has been evaluated under the influence of accelerated aging using pH measurement, the mechanical properties (tensile and elongation), FTIR and color changes. Findings The three consolidates reduced the acidity of treated samples significantly, but after ageing, it was observed that the pH of aged treated samples decreased slightly as compared to the untreated samples. The results of the mechanical properties showed the superiority of hydroxypropyl methylcellulose (Methocel) in improving the tensile and elongation forces of the samples compared to carrageenan and methyl hydroxyethyl cellulose even during the accelerated aging. Consolidation materials succeeded in reducing ΔE of the paper samples under accelerated aging, especially carrageenan. The IR spectra confirmed that no dramatic difference was observed in topically function vibrations of samples after treatment beside that the O-H stretching band intensity increased observably after treatment with the three consolidates, after ageing the treatment, and it protected the treated paper from oxidation processes as the infrared spectrum analysis showed a decrease in intensities of carbonyl and carboxyl groups as compared to aged untreated samples. Originality/value The research provides new biopolymers in strengthening the historical printed paper, where printed papers lack studies related to their conservation. This makes the current study a promising step for treating historical printed paper.

Structural and Magnetic Characterizations of Ruddlesden–Popper Family (Ca2-xNdxMnO4) Compound Synthesized by Ceramic Route

In this work, we were interested in the Ca2−xNdxMnO4 compounds when (0.1 ≤ x ≤ 0.4). These oxides are synthesized through the solid-state method. In this study, we investigated the evolution of the structure, the magnetic properties and the Mn3+/Mn4+ ratio with the Nd content. The morphological study shows a decrease in the size of the grain in relation to x. The X-ray diffraction reveals a transition from the tetragonal phase to the orthorhombic phase when x = 0.4. Magnetic measurements have been taken for all the compounds in the temperature range between 2 and 300 K. The temperature-dependent magnetic susceptibility shows the presence of three transitions TN, TC and TCO. A dramatic difference in magnetic susceptibility between ZFC and FC was observed below the Neel temperatures for Ca2-xNdxMnO4, which shows the onset of a ferromagnetic moment below these temperatures. This moment is caused by the Dzyaloshinskii–Moriya interaction.

Gradient and lamellar heterostructures for superior mechanical properties

Heterostructured (HS) materials are a novel class of materials with mechanical properties that are superior over their conventional homogeneous counterparts. They are composed of HS zones with a dramatic difference in mechanical behaviors, which produces a synergistic effect on mechanical properties that are above the prediction by the rule-of-mixtures. Among all heterostructures, the two most studied are grain-size gradient structure and heterolamellar structure. These two heterostructures produce typical heterogeneous deformation during tensile deformation, producing long-range back stress in the soft zones and forward stress in the hard zones, which collectively produces hetero deformation-induced (HDI) stress to enhance the yield strength before yielding, and HDI hardening after yielding to retain ductility. In this article, we will focus on these two types of heterostructures. The issues, concerns, and progress are reviewed with the emphasis on the synergistic effect of mechanical properties, the fundamentals of several special plastic behaviors (e.g., strain gradient, HDI hardening and strain hardening), the plastic deformation mechanism, and the relationship between the microstructure and properties.

Patterns and tempo of PCSK9 pseudogenizations suggest an ancient divergence in mammalian cholesterol homeostasis mechanisms

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a central role in cholesterol homeostasis in humans as a major regulator of LDLR levels. PCSK9 is an intriguing protease in that it does not act by proteolysis but by preventing LDLR recirculation from endosomes to the plasma membrane. This, and the inexistence of any other proteolytic substrate but itself could suggest that PCSK9 is an exquisite example of evolutionary fine-tuning. However, the gene has been lost in several mammalian species, and null alleles are present (albeit at low frequencies) in some human populations without apparently deleterious health effects, raising the possibility that the PCSK9 may have become dispensable in the mammalian lineage. To address this issue, we systematically recovered, assembled, corrected, annotated and analysed publicly available PCSK9 sequences for 420 eutherian species to determine the distribution, frequencies, mechanisms and timing of PCSK9 pseudogenization events, as well as the evolutionary pressures underlying the preservation or loss of the gene. We found a dramatic difference in the patterns of PCSK9 retention and loss between Euarchontoglires—where there is strong pressure for gene preservation—and Laurasiatheria, where multiple independent events have led to PCSK9 loss in most species. These results suggest that there is a fundamental difference in the regulation of cholesterol metabolism between Euarchontoglires and Laurasiatheria, which in turn has important implications for the use of Laurasiatheria species (e.g. pigs) as animal models of human cholesterol-related diseases.

Bioturbation of Thalassinoides from the Lower Cambrian Zhushadong Formation of Dengfeng area, Henan Province, North China

Bioturbation plays a critical role in sediment mixing and biogeochemical cycling between sediment and seawater. An abundance of bioturbation structures, dominated by Thalassinoides, occurs in carbonate rocks of the Cambrian Series 2 Zhushadong Formation in the Dengfeng area of western Henan Province, North China. Determination of elemental geochemistry can help to establish the influence of burrowing activities on sediment biogeochemical cycling, especially on changes in oxygen concentration and nutrient regeneration. Results show that there is a dramatic difference in the bioturbation intensity between the bioturbated limestone and laminated dolostone of the Zhushadong Formation in terms of productivity proxies (Baex, Cu, Ni, Sr/Ca) and redox proxies (V/Cr, V/Sc, Ni/Co). These changes may be related to the presence of Thalassinoides bioturbators, which alter the particle size and permeability of sediments, while also increase the oxygen concentration and capacity for nutrient regeneration. Comparison with modern studies shows that the sediment mixing and reworking induced by Thalassinoides bioturbators significantly changed the primary physical and chemical characteristics of the Cambrian sediment, triggering the substrate revolution and promoting biogeochemical cycling between sediment and seawater.

Photocatalytic Activity of Silver-Based Biomimetics Composites

Different Ag@TiO2 and Ag@ZnO catalysts, with nanowire (NW) structure, were synthesized containing different amounts of silver loading (1, 3, 5, and 10 wt.%) and characterized by FE-SEM, HRTEM, BET, XRD, Raman, XPS, and UV–vis. The photocatalytic activity of the composites was studied by the production of hydrogen via water splitting under UV–vis light and the degradation of the antibiotic ciprofloxacin. The maximum hydrogen production of all the silver-based catalysts was obtained with a silver loading of 10 wt.% under irradiation at 500 nm. Moreover, 10%Ag@TiO2 NWs was the catalyst with the highest activity in the hydrogen production reaction (1119 µmol/hg), being 18 times greater than the amount obtained with the pristine TiO2 NW catalyst. The most dramatic difference in hydrogen production was obtained with 10%Ag@TiO2-P25, 635 µmol/hg, being 36 times greater than the amount reported for the unmodified TiO2-P25 (18 µmol/hg). The enhancement of the catalytic activity is attributed to a synergism between the silver nanoparticles incorporated and the high surface area of the composites. In the case of the degradation of ciprofloxacin, all the silver-based catalysts degraded more than 70% of the antibiotic in 60 min. The catalyst that exhibited the best result was 3%Ag@ZnO commercial, with 99.72% of degradation. The control experiments and stability tests showed that photocatalysis was the route of degradation and the selected silver-based catalysts were stable after seven cycles, with less than 1% loss of efficiency per cycle. These results suggest that the catalysts could be employed in additional cycles without the need to be resynthesized, thus reducing remediation costs.

The “Wear and Tear” of African Americans in Louisiana with HIV/AIDs: More Than HIV.

This article examines the results of a 2010 sample of HIV+ African Americans in Louisiana within the larger context of health, educational, economic and incarceration disparities in the state. Similarities and differences between the sample and the general population of African Americans in the state were noted with the numbers incarcerated in the sample being the most dramatic difference. Over half of the sample had been incarcerated in a state recognized for its penchant for using the police and incarceration to control African Americans. The article concluded with attempts to connect the dots between vulnerability to HIV due to childhood trauma, a weathering from racism from an early age, educational deprivation, and policy choices such as abstinence-only sex education that raise the risks for young African Americans in Louisiana.

Oxidation Level and Glycidyl Ether Structure Determine Thermal Processability and Thermomechanical Properties of Arabinoxylan-Derived Thermoplastics

Herein we present arabinoxylan (AX)-based thermoplastics obtained by ring opening oxidation and subsequent reduction (dA-AX) combined with hydrophobization with three different glycidyl ethers [n-butyl (BuGE), isopropyl (iPrGE) and 2-ethylhexyl (EtHGE) glycidyl ether]. We also present the relationship of structural composition, thermal processing and thermomechanical properties. The BuGE and iPrGE etherified dA-AXs showed glass transition temperatures (T_g) far below their degradation temperatures and gave thermoplastic materials when compression-molded at 140˚C. The BuGE (3 mole) etherified dA-AX films at 19 and 31 % oxidation levels exclusively exhibit 244 % (±42) and 267 % (±72) elongation. In contrast, iPrGE-dA-AX samples with shorter and branched terminals in the side chains had maximum 60 % (±19) elongation. The dramatic difference in elongation is assumed to be due to the presence of longer alkoxide chains, higher molar substitution and dual T_g for the BuGE samples. Such superior elongation of AX thermoplastic films and its relationship with molar substitution and T_g has not been reported before.

Oxidation Level and Glycidyl Ether Structure Determine Thermal Processability and Thermomechanical Properties of Arabinoxylan-Derived Thermoplastics

Herein we present arabinoxylan (AX)-based thermoplastics obtained by ring opening oxidation and subsequent reduction (dA-AX) combined with hydrophobization with three different glycidyl ethers [n-butyl (BuGE), isopropyl (iPrGE) and 2-ethylhexyl (EtHGE) glycidyl ether]. We also present the relationship of structural composition, thermal processing and thermomechanical properties. The BuGE and iPrGE etherified dA-AXs showed glass transition temperatures (T_g) far below their degradation temperatures and gave thermoplastic materials when compression-molded at 140˚C. The BuGE (3 mole) etherified dA-AX films at 19 and 31 % oxidation levels exclusively exhibit 244 % (±42) and 267 % (±72) elongation. In contrast, iPrGE-dA-AX samples with shorter and branched terminals in the side chains had maximum 60 % (±19) elongation. The dramatic difference in elongation is assumed to be due to the presence of longer alkoxide chains, higher molar substitution and dual T_g for the BuGE samples. Such superior elongation of AX thermoplastic films and its relationship with molar substitution and T_g has not been reported before.