Interaction of the C-terminal tail region of the metabotropic glutamate receptor 7 with the protein kinase C substrate PICK1

Group III metabotropic glutamate receptors (mGluRs) are highly enriched in the presynaptic terminals of glutamatergic synapses where they mediate feedback inhibition of neurotransmitter release. Here, we used the yeast two-hybrid system to identify a direct interaction of the C-terminal tail region of mGluR7 with the rat homologue of the protein kinase C substrate PICK1. This interaction is specifically mediated by the very C-terminal amino acids of the receptor and can be reconstituted in human embryonic kidney 293 cells by transfection of full-length mGluR7 and PICK1 cDNAs. Quantitative beta-galactosidase assays revealed that among the different group III mGluRs, mGluR7 is the major PICK1 binding partner although other subfamily members can also interact with PICK1. These data indicate that PDZ domain-containing proteins might contribute to the presynaptic localization of group III mGluRs.     

酵母SOD分离纯化及其酶学性质的研究

目的发酵培养Y12 酵母菌分离制备酵母SOD并研究其部分酶学性质。方法用已筛选出的一株Y12 酵母菌对其在优化培养条件下发酵培养得到湿菌体 ,破壁抽提得SOD粗酶液 ,采用硫铵盐析、丙酮沉淀、SephadexG 10 0凝胶过滤和QAE SephadexA 5 0离子交换柱层析 ,分离得到酵母SOD并测定其部分酶学性质。结果Y12 酵母菌SOD产量达 12 6 3u·g-1湿菌体 ,分离得到酵母SOD ,该酶属Cu、Zn SOD ,比活力为 10 73 5u·mg-1,活力回收率为 5 4 1% ,紫外吸收峰在2 5 7 2nm ,分子质量为 32 4 5 6u ,亚基分子质量为 16 2 2 7u。结论此酵母SOD与文献中报道的动物血红细胞Cu、Zn SOD基本相近。     

The Effects of Water and a Protective Agent on Gamma-ray Induced Free Radicals in Mustard Seeds

Summary

Electron-spin-resonance experiments on irradiated seeds have shown that the radicals induced by gamma-radiation are very sensitive to the moisture-content of the seeds. However, at x-band frequencies the dielectric effect of the water in the sample has limited such experiments to moisture-contents of about 12 per cent. By using an E.S.R. spectrometer of low microwave frequency the gamma-induced radicals in white-mustard seeds have been studied with moisture-contents of up to 70 per cent by weight, and measurements made while gamma-irradiation was in progress. Both radical production and radical decay are studied in seed samples of various moisture-contents and in seeds treated with the protective agent AET.     

Clinico-demographical profile of keratomycosis in Delhi,North India

This study was undertaken to evaluate the clinico-demographical profile of keratomycosis. (January 2004 to January 2012). The corneal scrapings were processed by direct microscopic methods and standard culture techniques. Of 209 cases of keratitis studied, culture yielded growth in 80 cases (38.3%). Out of these 80 cases of growth, fungi were isolated in 77.5% and bacteria in 22.5%. The spectrum of keratomycosis was Aspergillus flavus (22.5%), Fusarium solani (16.1%), A. fumigatus (11.3%), Candida albicans (6.4%), etc., Routine surveillance of fungal keratitis is necessary to know the existing and emerging pattern of pathogens and to prevent use of un-warranted anti-microbial therapy.     

Aggregation‐induced changes in the chemical exchange saturation transfer (CEST) signals of proteins

Chemical exchange saturation transfer (CEST) is an MRI technique that allows mapping of biomolecules (small metabolites, proteins) with nearly the sensitivity of conventional water proton MRI. In living organisms, several tissue‐specific CEST effects have been observed and successfully applied to diagnostic imaging. In these studies, particularly the signals of proteins showed a distinct correlation with pathological changes. However, as CEST effects depend on various properties that determine and affect the chemical exchange processes, the origins of the observed signal changes remain to be understood. In this study, protein aggregation was identified as an additional process that is encoded in the CEST signals of proteins. Investigation of distinct proteins that are involved in pathological disorders, namely amyloid beta and huntingtin, revealed a significant decrease of all protein CEST signals upon controlled aggregation. This finding is of particular interest with regard to diagnostic imaging of patients with neurodegenerative diseases that involve amyloidogenesis, such as Alzheimer's or Huntington's disease. To investigate whether the observed CEST signal decrease also occurs in heterogeneous mixtures of aggregated cellular proteins, and thus prospectively in tissue, heat‐shocked yeast cell lysates were employed. Additionally, investigation of different cell compartments verified the assignment of the protein CEST signals to the soluble part of the proteome. The results of in vitro experiments demonstrate that aggregation affects the CEST signals of proteins. This observation can enable hypotheses for CEST imaging as a non‐invasive diagnostic tool for monitoring pathological alterations of the proteome in vivo.     

Conserved residues in yeast initiator tRNA calibrate initiation accuracy by regulating preinitiation complex stability at the start codon

Eukaryotic initiator tRNA (tRNA_i) contains several highly conserved unique sequence features, but their importance in accurate start codon selection was unknown. Here we show that conserved bases throughout tRNA_i, from the anticodon stem to acceptor stem, play key roles in ensuring the fidelity of start codon recognition in yeast cells. Substituting the conserved G31:C39 base pair in the anticodon stem with different pairs reduces accuracy (the Sui⁻ [suppressor of initiation codon] phenotype), whereas eliminating base pairing increases accuracy (the Ssu⁻ [suppressor of Sui⁻] phenotype). The latter defect is fully suppressed by a Sui⁻ substitution of T-loop residue A54. These genetic data are paralleled by opposing effects of Sui⁻ and Ssu⁻ substitutions on the stability of methionylated tRNA_i (Met-tRNA_i) binding (in the ternary complex [TC] with eIF2-GTP) to reconstituted preinitiation complexes (PICs). Disrupting the C3:G70 base pair in the acceptor stem produces a Sui⁻ phenotype and also reduces the rate of TC binding to 40S subunits in vitro and in vivo. Both defects are suppressed by an Ssu⁻ substitution in eIF1A that stabilizes the open/P_OUT conformation of the PIC that exists prior to start codon recognition. Our data indicate that these signature sequences of tRNA_i regulate accuracy by distinct mechanisms, promoting the open/P_OUT conformation of the PIC (for C3:G70) or destabilizing the closed/P_IN state (for G31:C39 and A54) that is critical for start codon recognition.     

硒酵母联合308nm准分子激光治疗白癜风的临床疗效观察

目的探讨硒酵母联合308nm准分子激光治疗白癜风的临床疗效。方法 200例白癜风患者按治疗方式分为两组：100例硒酵母联合308nm准分子激光治疗患者为观察组,同期100例单纯308nm准分子激光治疗患者为对照组。比较两组患者过氧化氢酶（CAT）、谷胱甘肽-过氧化物酶（GSH-PX）、丙二醛（MDA）、脂质过氧化物（LPO）、免疫球蛋白G（IgG）及其亚类、临床疗效。结果连续治疗16周后,观察组患者血清GSH-PX、CAT明显高于对照组（P〈0.05）;观察组患者MDA、LPO明显低于对照组（P〈0.05）。观察组患者IgG、IgG1、IgG2a、IgG2b和IgG3的抗体水平显著升高,与对照组比较差异具有统计学意义（P〈0.05）。对照组治疗总有效率为64.0%,观察组总有效率为84.0%,观察组疗效明显优于对照组（P〈0.05）。结论硒酵母联合308nm准分子激光治疗白癜风疗效确切,值得临床推广使用。