Identification of avermectin-high-producing strains by high-throughput screening methods

Avermectins produced by Streptomyces avermitilis are potent against a broad spectrum of nematode and arthropod parasites with low-level side effects on the host organisms. This study was designed to investigate a high-throughput screening strategy for the efficient identification of avermectin high-yield strains. The production protocol was miniaturized in 96 deep-well microplates. UV absorbance at 245 nm was used to monitor avermectin production. A good correlation between fermentation results in both 96 deep-well microplates and conventional Erlenmeyer flasks was observed. With this protocol, the production of avermectins was determined in less than 10 min for a full plate without compromising accuracy. The high-yield strain selected through this protocol was also tested in 360 m³ batch fermentation with 1.6-fold improved outcome. Thus, the development of this protocol is expected to accelerate the selection of superior avermectin-producing strains.     

陕西宁陕野化放飞朱鹮秋季觅食地选择与食物丰富度

于2008年秋季应用样方法对陕西宁陕县寨沟野化放飞朱鹮(Nipponia nippon)的觅食地和食物丰富度进行了调查。结果表明,朱鹮秋季的主要觅食地是冬水田,影响朱鹮觅食地选择的主要因素是人为干扰、觅食地开阔度和土壤松软程度;宁陕野化放飞区朱鹮觅食地中共发现记录动物36种,冬水田翻耕对朱鹮的食物丰富度和生物量无显著影响。总体上,在秋季游荡期朱鹮的食物并不丰富。     

Comparative proteomics approach to screening of potential diagnostic and therapeutic targets for oral squamous cell carcinoma

This work demonstrates that a comprehensive strategy of proteomics identification combined with further validation and detailed functional analysis should be adopted in the field of cancer biomarker discovery. A comparative proteomics approach was utilized to identify differentially expressed proteins in 10 oral squamous carcinoma samples paired with their corresponding normal tissues. A total of 52 significantly and consistently altered proteins were identified with eight of these being reported for the first time in oral squamous carcinoma. Of the eight newly implicated proteins, RACK1 was chosen for detailed analysis. RACK1 was demonstrated to be up-regulated in cancer at both the mRNA and protein levels. Immunohistochemical examination showed that the enhanced expression of RACK1 was correlated with the severity of the epithelial dysplasia as well as clinical stage, lymph node involvement, and recurrence, which are known indicators of a relatively poor prognosis in oral squamous carcinoma patients. RNA interference specifically targeted to silence RACK1 could initiate apoptosis of oral squamous carcinoma cells. Taken together, the results indicate that RACK1 is up-regulated in oral squamous carcinoma, not only being closely related to cell proliferation and apoptosis but also linked to clinical invasiveness and metastasis in carcinogenesis. The observations suggest that RACK1 may be a potential biomarker for early diagnosis, prognosis, and monitoring in the therapy of oral squamous carcinoma. Further this comprehensive strategy could be used for identifying other differentially expressed proteins that have potential to be candidate biomarkers of oral squamous carcinoma.     

PTEN deletion leads to deregulation of antioxidants and increased oxidative damage in mouse embryonic fibroblasts

Despite the significance of oxidative damage in carcinogenesis, the molecular mechanisms that lead to increased susceptibility to oxidative stress are not well understood. We now report a link between loss of protection against oxidative damage and loss of function of PTEN, a highly mutated tumor suppressor gene in a variety of human tumors. Using two-dimensional gel electrophoresis, combined with Western and Northern blot analyses, we found that PTEN deficiency in mouse embryonic fibroblasts (MEFs) displays deregulated expression of several antioxidant enzymes, including peroxiredoxins 1, 2, 5, and 6 and Cu, Zn superoxide dismutase. In these Pten-deleted MEFs, the basal levels of reactive oxygen species (ROS) were increased, and both the basal level and the ROS-induced oxidative damage of DNA were increased, as evidenced by increased levels of hydrogen peroxide (H2O2), superoxide anion, 8-hydroxy-2'-deoxyguanosine, and DNA double-strand breaks. We further show that Pten deletion is correlated with resistance to H2O2-induced expression of several antioxidants. These findings suggest an essential role for PTEN in maintaining the normal redox state of mouse embryonic fibroblasts against oxidative damage. They also provide a molecular link between PTEN, whose inactivation is known to be involved in a variety of human tumors, and antioxidants, whose perturbation leads to oxidative damage of cells.     

Synthesis and in vitro cytotoxicity of novel hydrophilic chiral 2-alkoxy-1,4-butanediamine platinum (II) complexes

Twenty-six new hydrophilic chiral 2-alkoxy-1,4-butanediamine platinum (II) complexes having a seven-membered ring structure between a bidentate carrier ligand and a platinum atom have been synthesized and most of them were evaluated for their in vitro cytotoxicity toward A549 human non-small cell lung carcinoma and HCT-116 human colon cancer cell lines. The cytotoxicities of platinum complexes are related to the nature of the carrier ligand and leaving group. Complex 5'b, viz. cis-dichloro[(2R)-ethoxy-1,4-butanediamine] platinum (II), exhibits the greatest potency among those 21 tested platinum complexes in both cell lines.     

The membrane-associated progesterone-binding protein 25-Dx is expressed in brain regions involved in water homeostasis and is up-regulated after traumatic brain injury

After traumatic brain injury, progesterone has important neuroprotective effects in the nervous system. There is better functional outcome and less oedema formation in pseudopregnant rat females (high levels of endogenous progesterone) than in males. In addition to intracellular progesterone receptors, membrane binding sites of the hormone such as 25-Dx may also be involved in neuroprotection. In the present study we investigated the distribution of the membrane-associated progesterone-binding protein 25-Dx in rat brain. Immunohistochemical analysis showed that 25-Dx is particularly abundant in the hypothalamic area, circumventricular organs, and ependymal cells of the lateral walls of the third and lateral ventricles. A strong signal was also detected in the meninges. Double immunofluorescence immunolabelling and confocal microscopy showed that 25-Dx is co-expressed with vasopressin in neurones of the paraventricular, supraoptic and retrochiasmatic nuclei. Levels of 25-Dx expression were higher in pseudopregnant females than in males. After traumatic brain injury, 25-Dx expression was up-regulated in neurones and induced in astrocytes, which play an important role in regulating water and ion homeostasis. The expression of 25-Dx in structures involved in CSF production (choroid plexus) and in osmoregulation (circumventricular organs, hypothalamus and meninges), and its up-regulation after brain damage, point to a novel and potentially important role of this progesterone-binding protein in the maintenance of water homeostasis after traumatic brain injury.     

Differential expression of the Quox-1 gene in normal human cells,early human embryo,and tumor cells

Quox-1 is the only gene in the hox family whose expression occurs throughout the developing central nervous system. The differential expression of the Quox-1 gene was studied in normal human tissues and tumor tissues. Marked expression of Quox-1 was detected in early human embryos, LCE cells, and HeLa cells, with weak to zero expression being detected in various normal human tissues. Immunocytochemistry analysis further confirmed that the Quox-1 protein was absent in normal human leukocytes. However, high levels of Quox-1 product were found in leukocytes of acute lymphocyte leukemia patients and in patients with a subtype of acute nonlymphocyte leukemia. In addition, Southern blot analysis showed that the genomic DNA of LCE, HeLa, and normal human leukocyte cells had a DNA rearrangement of the Quox-1 gene, suggesting that the rearrangement of genomic DNA might be the cause of differential expression in normal human tissues and tumor tissues. The data implied that the overexpression of Quox-1 was associated with tumors, and that there may be links between the processes of embryogenesis and carcinogenesis.     

内皮祖细胞在心脑血管疾病治疗中的应用

骨髓、外周血和脐血来源的内皮祖细胞取材和动员方便,能在体外扩增并能定向分化成功能性内皮细胞,在修复心肌梗死患者的心脏,治疗临床肢体缺血、冠状动脉疾病、脑中风,改善糖尿病患者的血管形成能力,定向抑制肿瘤血管生成,以及作为基因治疗导向载体和靶细胞等方面,具有广阔的应用前景。