一株存在有逆转录样病毒的肿瘤性小鼠早期T细胞株的建立及鉴定

从对正常LACA小鼠腹腔细胞的体外培养中,获单一细胞集落,由此集落细胞扩展建成一株淋巴样细胞株。由流式细胞计分析细胞表面标志显示。此株细胞表面具有不成熟的早期T细胞的表而抗原,为Thy-1.1~ ,PgP~ ,B2A2~ 及LFA-1~ ;不具有成熟T细胞表面抗原,为Ly 2~-及L3T4~-,亦不具有B细胞及巨噬细胞表面抗原,为SIg~-,Lyb 5~-及Mac-1~-。因而为早期T细胞株,命名为C 320细胞株。C 320细胞的生长不依赖于外源性IL_2的供应,已在体外维持一年半。此细胞分裂相活跃,染色体数目及形态均异常。1—5×10~6个C 320细胞腹腔接种裸鼠,于三周内引起腹水型肿瘤,并广泛转移至腹腔脏器,纵膈淋巴结及肺部。故C 320细胞为小鼠肿瘤性早期T细胞株。电子显微镜检查,见胞浆及胞膜上有病毒颗粒,形态酷似逆转录病毒C型,提示C 320细胞可能是逆转录病毒转化的肿瘤性早期T细胞株。     

Coenzyme Q10 reduces ethanol-induced apoptosis in corneal fibroblasts

Dilute ethanol (EtOH) is a widely used agent to remove the corneal epithelium during the modern refractive surgery. The application of EtOH may cause the underlying corneal fibroblasts to undergo apoptosis. This study was designed to investigate the protective effect and potential mechanism of the respiratory chain coenzyme Q(10) (CoQ(10)), an electron transporter of the mitochondrial respiratory chain and a ubiquitous free radical scavenger, against EtOH-induced apoptosis of corneal fibroblasts. Corneal fibroblasts were pretreated with CoQ(10) (10 μM) for 2 h, followed by exposure to different concentrations of EtOH (0.4, 2, 4, and 20%) for 20 s. After indicated incubation period (2-12 h), MTT assay was used to examine cell viability. Treated cells were further assessed by flow cytometry to identify apoptosis. Reactive oxygen species (ROS) and the change in mitochondrial membrane potential were assessed using dichlorodihydrofluorescein diacetate/2',7'-dichlorofluorescein (DCFH-DA/DCF) assays and flow-cytometric analysis of JC-1 staining, respectively. The activity and expression of caspases 2, 3, 8, and 9 were evaluated with a colorimetric assay and western blot analysis. We found that EtOH treatment significantly decreased the viability of corneal fibroblasts characterized by a higher percentage of apoptotic cells. CoQ(10) could antagonize the apoptosis inducing effect of EtOH. The inhibition of cell apoptosis by CoQ(10) was significant at 8 and 12 h after EtOH exposure. In EtOH-exposed corneal fibroblasts, CoQ(10) pretreatment significantly reduced mitochondrial depolarization and ROS production at 30, 60, 90, and 120 min and inhibited the activation and expression of caspases 2 and 3 at 2 h after EtOH exposure. In summary, pretreatment with CoQ(10) can inhibit mitochondrial depolarization, caspase activation, and cell apoptosis. These findings support the proposition that CoQ(10) plays an antiapoptotic role in corneal fibroblasts after ethanol exposure.     

南荻同源四倍体的研究

南荻变种“突节荻”的幼穗、下胚轴产生的带绿芽点愈伤组织,置于０．０５％秋水仙碱的ＭＳ无激素培养基上处理２４－４８ｈ,经培养而诱变成交异试管苗。细胞学鉴定确定其染色体数目为２ｎ＝４ｘ＝７６（ｘ＝１９）,花粉粒和气孔保卫细胞均增大,核仁数目增多。田间种植和测定,获得南荻同源四倍体新品系。该品系表现出生长势强,植株高大,茎粗、茎壁厚、节间长,产量高,而且纤维长,长宽比值大,是生产上能直接利用的一种优质高产的造纸新资源     

Dietary administration of a Gracilaria tenuistipitata extract enhances the immune response and resistance against Vibrio alginolyticus and white spot syndrome virus in the white shrimp Litopenaeus vannamei

The haemogram, phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, lysozyme activity, and the mitotic index of haematopoietic tissue (HPT) were examined after the white shrimp Litopenaeus vannamei had been fed diets containing the hot-water extract of Gracilaria tenuistipitata at 0 (control), 0.5, 1.0, and 2.0 g kg(-1) for 7-35 days. Results indicated that these parameters directly increased with the amount of extract and time, but slightly decreased after 35 days. RBs, SOD activity, and GPx activity reached the highest levels after 14 days, whereas PO and lysozyme activities reached the highest levels after 28 days. In a separate experiment, white shrimp L. vannamei, which had been fed diets containing the extract for 14 days, were challenged with Vibrio alginolyticus at 2 × 10(6) cfu shrimp(-1) and white spot syndrome virus (WSSV) at 1 × 10(3) copies shrimp(-1), and then placed in seawater. The survival rate of shrimp fed the extract-containing diets was significantly higher than that of shrimp fed the control diet at 72-144 h post-challenge. We concluded that dietary administration of the G. tenuistipitata extract at ≤1.0 g kg(-1) could enhance the innate immunity within 14 days as evidenced by the increases in immune parameters and mitotic index of HPT in shrimp and their enhanced resistance against V. alginolyticus and WSSV infections. Shrimp fed the extract-containing diets showed a higher and continuous increase in the humoral response indicating its persistent role in innate immunity.     

Functional characterization of kanB by complementing in engineered Streptomycesfradiae ?neo6::tsr

A putative aminotransferase gene, kanB, lies in the biosynthetic gene cluster of Streptomyces kanamyceticus ATCC 12853 and has 66% identity with neo6 in neomycin biosynthesis. Streptomyces fradiae ∆neo6::tsr was generated by disrupting neo6 in the neomycin producer Streptomyces fradiae. Neomycin production was completely abolished in the disruptant mutant but was restored through self-complementation of neo6. S. fradiae HN4 was generated through complementation with kanB in Streptomyces fradiae ∆neo6::tsr. Based on metabolite analysis by ESI/MS and LC/MS, neomycin production was restored in Streptomyces fradiae HN4. Thus, like neo6, kanB also functions as a 2-deoxy-scyllo-inosose aminotransferase that has dual functions in the formation of 2-deoxy-scyllo-inosose (DOS). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Envelope glycoprotein determinants of increased fusogenicity in a pathogenic simian-human immunodeficiency virus (SHIV-KB9) passaged in vivo

Changes in the envelope glycoprotein ectodomains of a nonpathogenic simian-human immunodeficiency virus (SHIV-89.6) that was serially passaged in vivo have been shown to be responsible for the increased pathogenicity of the resulting virus, SHIV-KB9 (G. B. Karlsson, et al., J. Exp. Med. 188:1159-1171, 1998). The 12 amino acid changes in the envelope glycoprotein ectodomains resulted in increased chemokine receptor-binding and syncytium-forming abilities. Here we identify the envelope glycoprotein determinants of these properties. A single amino acid change in the gp120 third variable (V3) loop was both necessary and sufficient for the observed increase in the binding of the SHIV-KB9 gp120 glycoprotein to the CCR5 chemokine receptor. The increased syncytium-forming ability of SHIV-KB9 involved, in addition to the V3 loop change, changes in the second conserved (C2) region of gp120 (residue 225) and in the gp41 ectodomain (residues 564 and 567). The C2 and gp41 ectodomain changes influenced syncytium formation in a cooperative manner. Changes in the V1/V2 gp120 variable loops exerted a negative effect on syncytium formation and chemokine receptor binding, supporting a previously described role of these changes in immune evasion. The definition of the passage-associated changes that determine the efficiency of chemokine receptor binding and membrane fusogenicity will allow evaluation of the contribution of these properties to in vivo CD4-positive lymphocyte depletion.     

Effects of zinc supplementation on the plasma glucose level and insulin activity in genetically obese (ob/ob) mice

The effects of zinc supplementation (20 mM ZnCl₂ from the drinking water for eight weeks) on plasma glucose and insulin levels, as well as its in vitro effect on lipogenesis and lipolysis in adipocytes were studied in genetically obese (ob/ob) mice and their lean controls (+/?). Zinc supplementation reduced the fasting plasma glucose levels in both obese and lean mice by 21 and 25%, respectively (p < 0.05). Fasting plasma insulin levels were significantly decreased by 42% in obese mice after zinc treatment. In obese mice, zinc supplementation also attenuated the glycemic response by 34% after the glucose load. The insulin-like effect of zinc on lipogenesis in adipocytes was significantly increased by 80% in lean mice. However, the increment of 74% on lipogenesis in obese mice was observed only when the zinc plus insulin treatment was given. This study reveals that zinc supplementation alleviated the hyperglycemia of ob/ob mice, which may be related to its effect on the enhancement of insulin activity.