溶瘤病毒载体研究进展

溶瘤病毒(oncolytic virus,OVs)疗法是治疗肿瘤的一种新方法,它可通过直接杀死肿瘤细胞并引起机体的免疫反应发挥作用.然而天然溶瘤病毒有一定的局限性,因此需将各种不同的病毒作为载体,通过基因修饰的方法增强或减弱病毒毒力并导入新的功能性基因,以提高其溶瘤作用.目前可以作为溶瘤病毒载体的有单纯疱疹病毒、腺病毒、牛痘病毒、水泡性口炎病毒、麻疹病毒、腮腺炎病毒、脊髓灰质炎病毒等.这些病毒载体均可通过不同的基因修饰方法,靶向性感染并杀死不同的肿瘤细胞,获得较好的溶瘤作用.本文综述了几种溶瘤病毒载体的基因修饰方法,以及修饰后的溶瘤效果.     

A Novel Fission Yeast Gene, tht1+, Is Required for the Fusion of Nuclear Envelopes during Karyogamy

We have isolated a fission yeast karyogamy mutant, tht1, in which nuclear congression and the association of two spindle pole bodies occurs but the subsequent fusion of nuclear envelopes is blocked. The tht1 mutation does not prevent meiosis, so cells execute meiosis with two unfused nuclei, leading to the production of aberrant asci. The tht1⁺ gene was cloned and sequenced. Predicted amino acid sequence has no significant homology to previously known proteins but strongly suggests that it is a type I membrane protein. The tht1⁺ gene is dispensable for vegetative growth and expressed only in conjugating cells. Tht1p is a glycoprotein susceptible to endoglycosilase H digestion. Site- directed mutagenesis showed that the N-glycosylation site, as well as the COOH-terminal region of Tht1p, is essential for its function. A protease protection assay indicated that the COOH terminus is cytoplasmic. Immunocytological analysis using a HA-tagged Tht1p suggested that the protein is localized in nuclear envelopes and in the ER during karyogamy and that its levels are reduced in cells containing fused nuclei.     

Structures, spectroscopic and thermodynamic properties of U2On (n = 0 ∼ 2, 4) molecules: a density functional theory study

The equilibrium structures, spectroscopic and thermodynamic parameters [entropy (S), internal energy (E), heat capacity (C _p)] of U₂, U₂O, U₂O₂ and U₂O₄ uranium oxide molecules were investigated systematically using density functional theory (DFT). Our computations indicated that the ground electronic state of U₂ is the septet state and the equilibrium bond length is 2.194 Å; the ground electronic state of U₂O and U₂O₂ were found to be $ {\tilde{X}}^3\varPhi $ and $ {\tilde{X}}^3{\sum}_{\mathrm{g}} $ with stable C _∞v and D _∞h linear structures, respectively. The bridge-bonded structure with D _2h symmetry and $ {\tilde{X}}^3{\mathrm{B}}_{1\mathrm{g}} $ state is the most stable configuration for the U₂O₄ molecule. Mulliken population analyses show that U atoms always lose electrons to become the donor and O atoms always obtain electrons as the acceptor. Molecular orbital analyses demonstrated that the frontier orbitals of the title molecules were contributed mostly by 5f atomic orbitals of U atoms. Vibrational frequencies analyses indicate that the maximum absorption peaks stem from the stretching mode of U–O bonds in U₂O, U₂O₂ and U₂O₄. In addition, thermodynamic data of U₂O_n (n?=?0?～?4) molecules at elevated temperatures of 293.0 K to 393.0 K was predicted.     

Pseudonocardia yuanmoensis sp. nov., a novel actinobacterium isolated from soil in Yunnan, south-west China

A novel Gram-stain positive, aerobic, non-motile, spore-forming actinobacterium, designated YIM 75926^T, was isolated from a soil sample collected at soil forest in Yuanmo county of Yunnan province, south-west China. Its taxonomic position was investigated by a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequences showed that the novel strain YIM 75926^T belongs to the genus Pseudonocardia and was closely related to Pseudonocardia halophobica DSM 43089^T (98.1% similarity). Strain YIM 75926^T had MK-8 (H₄) as the predominant menaquinone. The whole organism hydrolysates mainly consisted of meso-diaminopimelic acid, mannose, glucose, galactose and arabinose. The major cellular fatty acids were iso-C_16:0 (37.16%) and C_16:0 (12.43%). The DNA G+C content of strain YIM 75926^T was 70.6 mol%. The resultant phylogenetic trees further showed that strain YIM 75926^T belong to Pseudonocardia and had a distinct subclade within the evolutionary radiation of the genus Pseudonocardia. On the basis of its comparative analysis of phenotypic and genotypic characteristics, it is proposed that strain YIM 75926^T represent a novel species of the genus Pseudonocardia, named Pseudonocardia yuanmoensis sp. nov. The type strain is YIM 75926^T (=CCTCC AA 2011017^T = JCM 18055^T).     

空气污染与神经退行性疾病

随着现代社会工业的发展,空气污染日益严重,空气污染对人体的损害也越来越大。空气污染中的有害物质,能通过各种途径引起各系统的疾病,甚至会影响儿童的身体和智力发育。研究发现,长期暴露或急性暴露在某些空气污染物中可以直接损伤中枢神经系统,或污染物引起呼吸系统和免疫系统等产生有害因子,通过外周循环到达大脑,导致大脑的神经炎症、神经毒性、氧化应激等反应,最终产生神经退行性病变,如阿尔茨海默病（Alzheimer’s disease,AD）、帕金森病（Parkinson’s disease,PD）等。     

Meiotic cohesins modulate chromosome compaction during meiotic prophase in fission yeast

The meiotic cohesin Rec8 is required for the stepwise segregation of chromosomes during the two rounds of meiotic division. By directly measuring chromosome compaction in living cells of the fission yeast Schizosaccharomyces pombe, we found an additional role for the meiotic cohesin in the compaction of chromosomes during meiotic prophase. In the absence of Rec8, chromosomes were decompacted relative to those of wild-type cells. Conversely, loss of the cohesin-associated protein Pds5 resulted in hypercompaction. Although this hypercompaction requires Rec8, binding of Rec8 to chromatin was reduced in the absence of Pds5, indicating that Pds5 promotes chromosome association of Rec8. To explain these observations, we propose that meiotic prophase chromosomes are organized as chromatin loops emanating from a Rec8-containing axis: the absence of Rec8 disrupts the axis, resulting in disorganized chromosomes, whereas reduced Rec8 loading results in a longitudinally compacted axis with fewer attachment points and longer chromatin loops.     

Lysobacter thermophilus sp. nov., isolated from a geothermal soil sample in Tengchong, south-west China

A Gram-negative and aerobic bacterium, designated YIM 77875^T, was isolated from a geothermal soil sample collected at Rehai National Park, Tengchong, Yunnan Province, south-west China. Bacterial growth occurred from 37 to 65 °C (optimum 50 °C), pH 6.0–8.0 (optimum pH 7.0) and 0–1 % NaCl (w/v). Cells were rod-shaped and colonies were convex, circular, smooth, yellow and non-transparent. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain YIM 77875^T belongs to the genus Lysobacter. The 16S rRNA gene sequence similarity values between strain YIM 77875^T and other species of the genus Lysobacter were all below 94.7 %. The polar lipids of strain YIM 77875^T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and five unknown phospholipids. The predominant respiratory quinone was Q-8 and the G+C content was 68.8 mol%. Major fatty acids were iso-C_16:0, iso-C_15:0 and iso-C_11:0. On the basis of the morphological and chemotaxonomic characteristics, as well as genotypic data, strain YIM 77875^T represents a novel species, Lysobacter thermophilus sp. nov., in the genus Lysobacter. The type strain is YIM 77875^T (CCTCC AB 2012064^T = KCTC 32020^T).