On the Kernel of Restriction of Characters*

Let G be a finite group, H be a proper subgroup of G, and S be a unitary subring of C. The kernel of the restriction map S[Irr(G)] → S[Irr(H)] as a ring homomorphism is studied. As a corollary, the main result in [Isaacs, I. M. and Navarro, G., Injective restriction of characters, Arch. Math., 108, 2017, 437–439] is reproved.     

Dye-ligand chromatography for the resolution and purification of restriction endonucleases

The resolution of restriction endonucleases from the same microorganism is conventionally achieved by lengthy fractionation protocols. We now report effective single-step procedures that exploit dye-ligand chromatography for the resolution and purification of restriction enzymes. After suitable initial screening, we demonstrated that resolution of two restriction activites can be achieved in one chromatographic step, and further purification can subsequently be effected using selected dye-adsorbents. Accordingly, we resolved in one step, Hpa I from Hpa II, Hind II from Hind III, and Sac I from Sac II. Furthermore, a three-step Chromatographic procedure has been developed to purify EcoRV suitable for commercial exploitation, as judged by the “overdigestion” and “cut-ligate-recut” quality control tests.     

Effect of glutaraldehyde on the activity of some DNA restriction endonucleases

The effect of the bifunctional crosslinking reagent glutaraldehyde on the activity of the restriction enzymes Bam HI,Hind III, EcoRI, and Tthlll I was investigated. The four enzymes exhibited differential sensitivity to inactivation. Tthlll I was the most sensitive, with activity losses occurring at levels of 0.0025% and above.Hind III was the most stable of the four and remained fully active at concentrations as high as 0.075%. Addition of BSA to incubation mixtures generally had a stabilizing effect. Implications of these results for the design of glutaraldehyde-based methods for the immobilization of restriction endonucleases are discussed.     

Chemical shift driven geometry optimization

A new method for refinement of 3D molecular structures by geometry optimization is presented. Prerequisites are a force field and a very fast procedure for the calculation of chemical shifts in every step of optimization. To the energy, provided by the force field (COSMOS force field), a pseudoenergy, depending on the difference between experimental and calculated chemical shifts, is added. In addition to the energy gradients, pseudoforces are computed. This requires the derivatives of the chemical shifts with respect to the coordinates. The pseudoforces are analytically derived from the integral expressions of the bond polarization theory. Single chemical shift values attributed to corresponding atoms are considered for structural correction. As a first example, this method is applied for proton position refinement of the D-mannitol X-ray structure. A crystal structure refinement with 13C chemical shift pseudoforces is carried out.     

New tetraphenylpyridinium-baseci luminogens with aggregation-induced emission characteristics

The research on aggregation-induced emission （AIE） has drawn increasing interests in the past decade. With the efforts scientists paid, a variety of AIE systems have been developed, among which the tetraphenylethelene and silole derivatives are the most studied. Development of new AIE systems could further enrich the AIE molecules and promote the development of AIE area. In this communication, we prepared a new AIE system based on 1,2,4,6-tetraphenylpyridinium ions according to the restriction of intramolecular rotation mechanism. These molecules could be facilely synthesized via one-step and one-pot reaction. The ionic AIE-active molecules could find wide application in sensing and optoelectronic areas.     

Nuclear Magnetic Resonance-Based Blood Metabolic Profiles of Rats Exposed to Short-Term Caloric Restriction

Caloric restriction increases the life-span of a number of organisms. The relationship between the increase in life-span and the extent of caloric restriction, however, varies among species. The underlying mechanisms are yet unknown, but appear to be related to changes in metabolism. In order to investigate the metabolic response of caloric restriction of rats, here is presented the first nuclear magnetic resonance (NMR) spectroscopy-based study of how blood metabolite profiles are influenced by graded levels of caloric restriction. The study involved three groups of obese rats exposed to 0, 20, and 40 percent caloric restriction for five days. Blood serum from each individual was analyzed by ¹H NMR and the resulting spectra were subjected to multivariate analysis by unsupervised principal component analysis and supervised orthogonal-partial least square discriminant analysis. The analyses revealed that a response to caloric restriction was present at 20 percent caloric restriction. The metabolites that distinguished the profiles at 20 percent restriction deviated from those at 40 percent restriction. The changes induced by caloric restriction were most clearly observed as an increased level of 3-hydroxybutyrate, and decreased levels of lipids and pyruvate. The metabolic responses of rats exposed to caloric restriction are in good agreement with a switch in metabolism from anabolic pathways towards fatty acid catabolism and gluconeogenesis, which is consistent with previous observations for mice.     

Study on detection of mutation DNA fragment in gastric cancer by restriction endonuclease fingerprinting with capillary electrophoresis

The DNA fragment detection focusing technique has further enhanced the sensitivity and information of DNA targets. The DNA fragment detection method was established by capillary electrophoresis with laser‐induced fluorescence detection and restriction endonuclease chromatographic fingerprinting (CE‐LIF‐REF) in our experiment. The silica capillary column was coated with short linear polyarclarylamide (SLPA) using nongel sieving technology. The excision product of various restricted enzymes of DNA fragments was obtained by REF with the molecular biology software Primer Premier 5. The PBR322/BsuRI DNA marker was used to establish the optimization method. The markers were focused electrophoretically and detected by CE‐LIF. The results demonstrate that the CE‐LIF‐REF with SLPA can improve separation, sensitivity and speed of analysis. This technique may be applied to analysis of the excision product of various restricted enzymes of prokaryotic plasmid (pIRES2), eukaryote plasmid (pcDNA3.1) and the PCR product of codon 248 region of gastric cancer tissue. The results suggest that this method could very sensitively separate the excision products of various restricted enzymes at a much better resolution than the traditional agarose electrophoresis. Copyright © 2011 John Wiley & Sons, Ltd.     

Recent Advances of AIE-Active Conjugated Polymers: Synthesis and Application

Conjugated polymers (CPs) have long been recognized as an important class of materials. The highly conjugated backbone of the CPs will facilitate the rapid exciton migration and result in amplification of fluorescence signals. However, CPs are likely to aggregate and form excimers in solid states, directly leading to the fluorescence quenching, namely aggregation-caused quenching (ACQ), hence inhibiting their prospective utilizations in a large degree. Since the effect of aggregation-induced emission (AIE) is opposite to that of notorious ACQ, the AIE has raised great attention from scientists. CPs with AIE or aggregation-enhanced emission (AEE) features may help to solve the ACQ problem and meanwhile impart polymers with new properties and practical applications. In this review, we summarize the recent progress on the preparation of CPs with AIE or AEE characteristics, where AIE-active luminogens are located at polymer backbones or pendants. Their potential applications including fluorescent sensors, biological probes, and active layers for the fabrication of light-emitting diodes are also described.