Overexpression of UBA5 in Cells Mimics the Phenotype of Cells Lacking UBA5

Ufmylation is a posttranslational modification in which the modifier UFM1 is attached to target proteins. This conjugation requires the concerted work of three enzymes named UBA5, UFC1, and UFL1. Initially, UBA5 activates UFM1 in a process that ends with UFM1 attached to UBA5’s active site Cys. Then, in a trans-thiolation reaction, UFM1 is transferred from UBA5 to UFC1, forming a thioester bond with the latter. Finally, with the help of UFL1, UFM1 is transferred to the final destination—a lysine residue on a target protein. Therefore, not surprisingly, deletion of one of these enzymes abrogates the conjugation process. However, how overexpression of these enzymes affects this process is not yet clear. Here we found, unexpectedly, that overexpression of UBA5, but not UFC1, damages the ability of cells to migrate, in a similar way to cells lacking UBA5 or UFC1. At the mechanistic level, we found that overexpression of UBA5 reverses the trans-thiolation reaction, thereby leading to a back transfer of UFM1 from UFC1 to UBA5. This, as seen in cells lacking UBA5, reduces the level of charged UFC1 and therefore harms the conjugation process. In contrast, co-expression of UBA5 with UFM1 abolishes this effect, suggesting that the reverse transfer of UFM1 from UFC1 to UBA5 depends on the level of free UFM1. Overall, our results propose that the cellular expression level of the UFM1 conjugation enzymes has to be tightly regulated to ensure the proper directionality of UFM1 transfer.     

Grafting of N,N′‐methylenebisacrylamide onto cellulose using Co(III)‐acetylacetonate complex in aqueous medium

The grafting of N,N′‐methylenebisacrylamide (N,N′‐MBA) onto cellulose is carried out using the cobaltacetylacetonate complex (Co(acac)₃) under nitrogen atmosphere at 40°C. The rate of graft copolymerization has been studied as a function of [N,N′‐MBA], [Co(acac)₃], and temperature. The activation energy of grafting is found to be 156.0 k J mol⁻¹ within the temperature range of 30–60°C. The effect of perchloric acid, methanol, and surfactants on graft yield has also been studied and results are suitably explained. The higher efficiency of the metal chelate in initiation of graft copolymerization has been assumed due to the coordination of the π electrons of the N,N′‐MBA with the metal chelate, which facilitated the formation of the radicals through homolytic cleavage of metal–oxygen bond of the cobalt acetylacetonate complex. On the basis of the results, a suitable kinetic scheme for graft copolymerization is presented and rate expression is derived. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 906–912, 2000     

The influence of lubricant on the morphology of ultra-high molecular weight polyethylene wear debris generated in laboratory tests.

Since the implication of polyethylene wear debris as a major cause of osteolysis in total joint replacements, there has been much interest in polyethylene wear studies and in cell culture studies using ultra-high molecular weight polyethylene (UHMWPE) wear debris. Studies have shown that particles in the 0.1-10 microns size range are particularly important in causing adverse cellular reactions resulting in osteolysis. The morphology, the mass and size distributions, and the number of wear particles produced at the joint surfaces are influenced by the tribological conditions at the joint. Laboratory wear tests are used to investigate the wear properties of prosthetic joint materials and different research groups have used different lubricants in these tests. This paper shows that the volumetric wear and morphology of UHMWPE particles generated in vitro are influenced by the type of lubricant used. This study compared, quantitatively, UHMWPE wear debris generated in deionized water to debris that was generated in a system lubricated by bovine serum which was diluted to 25 per cent. The wear factors of UHMWPE in water and serum lubricants were significantly different (p < 0.05). UHMWPE wore 14 times more in water than in serum. Quantitative analysis of the wear particles showed that the debris that was generated in serum was morphologically different from debris that was produced in a water-lubricated system. Furthermore, the particles produced in serum showed a closer similarity to those found in retrieved acetabular tissues.     

Effects of Thermal and Cryogenic Conditionings on Flexural Behavior of Thermally Shocked Cu-Al2O3 Micro and NanoComposites

This investigation has used flexural test to explore the effects of thermal treatments, i.e., high-temperature and cryogenic environments on the mechanical property of Al₂O₃ particulate-reinforced Cu metal matrix micro and nanocomposites in ex-situ and in-situ conditions. Cu-5 vol. pct Al₂O₃ micro (10 μm)- and nanocomposites (<50 nm) fabricated by powder metallurgy route were subjected to up-thermal shock cycle [193 K to 353 K (?80 °C to 80 °C)] and down-thermal shock cycle [353 K to 193 K (from 80 °C to ?80 °C)] for different time periods followed by 3-point bend test. One batch of specimens (micro and nanocomposites) was conditioned at 353 K and 193 K (80 °C and ?80 °C) separately followed by 3-point flexural test. High-temperature flexural test was performed at 373 K and 523 K (80 °C and 250 °C) on the micro and nanocomposites. All the fractured samples obtained after various thermal treatments were studied under scanning electron microscope (SEM). The development of thermal stresses quite often results in concentration of residual stresses at the particle/matrix interface eventually weakening it. Enhancement of flexural strength was recorded for down- as well as for up-thermal shock in microcomposites. The high-temperature flexural strengths of micro and nanocomposites are lower than those at ambient temperature. The amelioration and declination in mechanical properties as a consequence of thermal shock, thermal conditioning, and high-temperature flexural testing have been discussed in the light of fractography.     

Ionic liquid mediated application of nano zinc oxide on cotton fabric for multi-functional properties

In this work, nano zinc oxide (nano-ZnO) was applied onto cotton fabric by exhaustion method using an ionic liquid (IL), 1-butyl 3-methyl imidazolium chloride [BMIM][Cl], to improve its uptake and fixation. Effect of temperature on the exhaustion of nano-ZnO in the presence of ionic liquid was investigated. A spectrophotometric method was established to determine the concentration of nano-ZnO in the exhausted bath. Treated cotton fabrics were characterized using Fourier transform infrared, scanning electron microscope, atomic absorption spectroscopy, X-ray diffraction, Thermo gravimetric analysis and UV spectrophotometry. Washing durability test using the AATCC 61-2003 method demonstrated that the amount of nano-ZnO retained in the cotton substrate was sufficient enough to exhibit 50+ UV protection and 99% inhibition against the tested pathogenic micro-organisms. A plausible mechanism for better exhaustion of nano-ZnO on cotton fabric has been proposed on the basis of ionic liquid driven swelling property of the cotton polymer.     

Ion‐conductivity study and anomalous diffusion analysis of plasticized gelatin films

In this article, we report a study on ion conduction in gelatin films with different concentrations of glycerol as a plasticizer; these films might be a candidate for electrolyte materials in solid polymer batteries. The ion conductivity was appreciable, showing a maximum of about 9.14 × 10^?3 S/m at room temperature without the addition of any ionic salt. Analysis of the impedance measurements was done with a model based on material properties instead of the usual equivalent circuit formalism, where circuit elements are difficult to interpret. Generalized calculus was used to model the anomalous diffusion in the system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3018–3024, 2013     

Thermal and electrical behavior of silver chloride/polyaniline nanocomposite synthesized in aqueous medium using hydrogen peroxide

Nanocomposites of AgCl/PANI were synthesized by chemical polymerization/precipitation in aqueous HCl solution using both aniline monomer and AgNO₃ precursors in different molar ratio in PVP. Silver ions interact with PVP which restrict the bulk growth of AgCl and keep it in nanosized. During synthesis, AgCl NPs got entrapped in PANI chains through inter-chain hydrogen bonding. TGA studies showed complete decomposition of polymer chains occurred at 30–40 °C higher temperature than PANI alone. DSC studies indicate higher thermal stability of the composite, which is due to more heat flow for decomposition of polymer chains indicating compact packing of polymer matrix with AgCl NPs having large surface area to volume ratio. The TEM image showed spherical NPs were randomly dispersed in a polymer matrix and from XRD data crystalline nature of composite was seen. In FT-IR spectrum strong absorption band of a carbonyl stretching group due to PVP indicates its presence on nanoparticle surface in composite. Thin films of nanocomposite were spin casted on ITO coated glass surface. Electrical conductance was calculated from I–V data which was found to be in the range of 10^?2–10^?7 S cm^?1 depending on the concentration of NPs in it. These composites may find applications in solar cells as semiconductor material and for designing multiarray sensors for quality interpretation of beverages on the basis of their conductance changes using soft computing techniques.     

The effects of sorbates on the ensilage of chopped whole-plant maize and lucerne

The incorporation of (a) sorbic acid (0.18 and 0.90 g kg^?1, fresh weight basis) and potassium sorbate (0.90 g kg^?1) with chopped lucerne, and (b) sorbic acid (0.90 g kg^?1) and potassium sorbate (0.90 g kg^?1) with chopped maize (whole-plant) at the time of ensiling, led to a reduction in the surface spoilage associated with the ensilage of these two forages. Use of sorbic acid (0.90 g kg^?1) and potassium sorbate (0.90 g kg^?1) led to (a) a reduction of volatile nitrogen (VN), higher levels of residual water-soluble carbohydrates (WSC) in lucerne silage and more aerobically stable lucerne silage and (b) a reduction in weight loss, population of yeasts and moulds, and VN, higher levels of WSC in maize silage and more aerobically stable maize silage when compared to the untreated forages or forages treated with sorbic acid and potssium sorbate at 0.045 and 0.18 g kg^?1 (fresh weight basis), respectively.