影响大肠杆菌中外源基因表达的因素

大肠杆菌已经被广泛地应用于表达各种外源基因,但是,不同的外源基因在表达效率上却有很大的差异,文章综述了影响大肠杆菌中外源基因表达的因素,这将有助于认识大肠杆菌中外源基因表达的规律,以便采取有效的方法提高外源基因在大肠杆菌中的表达效率．     

红原鸡与家鸡的亲缘关系研究

对中国红原鸡滇地亚种和海南亚种与我国茶花鸡,泰和鸡和寿光鸡等地方鸡种以及芦花鸡,洛岛红等外国鸡种进行了血型（３个位点,１３个等位基因）,蛋白质（酶）多态（５个位点,１１个等位基因）和ＤＮＡ指纹分析,结果表明,红原鸡与茶花鸡（原始型品种）的亲缘关系较近;与泰和鸡,寿光鸡,芦花鸡,洛岛红（进化型品种）的亲缘关系较远,呈红原鸡－茶花鸡－泰和鸡,寿光鸡或芦花鸡,洛岛红这样一个进化阶梯,以上结果与国外资料（     

Genetics and Resistance Mechanism of the Cucumber (Cucumis sativus L.) Against Powdery Mildew

Journal of Plant Growth Regulation - Powdery mildew (PM) is one of the most severe foliar diseases in cucumbers (Cucumis sativus L.), but the inheritance of PM resistance remains unclear. The...     

SIRT1 deacetylase protects against neurodegeneration in models for Alzheimer's disease and amyotrophic lateral sclerosis

A progressive loss of neurons with age underlies a variety of debilitating neurological disorders, including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), yet few effective treatments are currently available. The SIR2 gene promotes longevity in a variety of organisms and may underlie the health benefits of caloric restriction, a diet that delays aging and neurodegeneration in mammals. Here, we report that a human homologue of SIR2, SIRT1, is upregulated in mouse models for AD, ALS and in primary neurons challenged with neurotoxic insults. In cell-based models for AD/tauopathies and ALS, SIRT1 and resveratrol, a SIRT1-activating molecule, both promote neuronal survival. In the inducible p25 transgenic mouse, a model of AD and tauopathies, resveratrol reduced neurodegeneration in the hippocampus, prevented learning impairment, and decreased the acetylation of the known SIRT1 substrates PGC-1alpha and p53. Furthermore, injection of SIRT1 lentivirus in the hippocampus of p25 transgenic mice conferred significant protection against neurodegeneration. Thus, SIRT1 constitutes a unique molecular link between aging and human neurodegenerative disorders and provides a promising avenue for therapeutic intervention.     

Synthesis and bioevaluation of N-(arylalkyl)-homospermidine conjugates

N1-(Arylalkyl)homospermidines (1c-1f) and terminally piperazine-substituted homospermidine conjugates (2a-2e) were synthesized and evaluated for cytotoxicity in mouse leukemia L1210, alpha-difluoromethylornithine (DFMO)-treated L1210, melanoma B16, spermidine (SPD)-treated B16, and HeLa cell lines. Results demonstrated that homospermidine was a more effective vector than piperazine-substituted homospermidine in ferrying diverse arenes into cells via the polyamine transporter. The leading compound, 9-anthracenemethyl-homospermidine (1a), was shown to induce apoptosis in B16 cells and IL-3 dependent FL5.12A pro-B cells. The novel conjugate 4-biphenylmethyl-homospermidine (1e) could also induce apoptosis. However, it exhibited different effect on the cell cycle of B16 cells compared to 1a.     

Characterization of hypothetical proteins Cpn0146, 0147, 0284 &; 0285 that are predicted to be in the <Emphasis Type="Italic">Chlamydia pneumoniae</Emphasis> inclusion membrane

Background  

Although more than 100 Chlamydia pneumoniae hypothetical proteins have been predicted to be inclusion membrane proteins, only a few have been experimentally demonstrated to be in the inclusion membrane. Using antibodies raised with fusion proteins, we characterized four such hypothetical proteins encoded by two gene clusters (Cpn0146-147 and Cpn0284-285) in the C. pneumoniae genome.     

Co-expression of IL-18 binding protein and IL-4 regulates Th1/Th2 cytokine response in murine collagen-induced arthritis

We constructed a recombinant adenoviral vector containing a murine interleukin （IL）-18 binding protein （mlL-18BP） and murine IL-4 （mIL-4） fusion gene （AdmIL-18BP/mIL.4） and used a gene therapy approach to investigate the role of IL-18BP and IL-4 in modulating the T-helperl and T-helper2 （Th1/Th2） balance in mice with collagen-induced arthritis （CIA）. Mice with CIA were intra-articularly injected with 107 pfu/6 μl ofeitherAdmIL.18BP/mIL-4, or a controladenovirus, or with the control vehicle （phosphate-buffered saline）. After intra-articular gene therapy with AdmIL-18BP/mIL-4, the serum levels of tumor necrosis factor-α （TNF-α）, T-interferon （IFN-γ）, IL-4, IL-10, and IL-18 in mice with CIA were assessed by ELISA. IFN-T-expressing and IL-4-expressing CD4^＋ T cells from mice splenocytes were monitored by flow cytometry. Mice with CIA at weeks 1, 2, and 4 after intraarticular injection of AdmIL-18BP/mIL-4 showed significantly increased serum concentrations of IL-4 and IL-10 （P〈0.01 at all time points） but greatly decreased serum concentrations ofIFN-γ, TNF-α and IL-β （P〈0.01 at all time points ） compared to both the con trol adenovirus and phospha tebuffered saline control groups. The percentage of LFN-γ- producing CD4^＋ T cells was significantly decreased in response to local AdmIL-18BP/mIL-4 treatment. The percentage of IL-4-producing CD4^＋ T cells increased significantly at 1 week after local injection of AdmIL-18BP/ mIL-4 then returned to normal by week 4. These data indicated the significant modifying effects on the Th1/Th2 imbalance in murine CIA produced by local overexpression of IL-18BP and IL-4. Combination treatment with IL-18BP and IL-4 is a promising potential therapy for rheumatoid arthritis.     

Mutant <Emphasis Type="Italic">TP53</Emphasis> G245C and R273H promote cellular malignancy in esophageal squamous cell carcinoma

Background

TP53 gene mutations occur in more than 50% of human cancers and the vast majority of these mutations in human cancers are missense mutations, which broadly occur in DNA binding domain (DBD) (Amino acids 102–292) and mainly reside in six “hotspot” residues. TP53 G245C and R273H point mutations are two of the most frequent mutations in tumors and have been verified in several different cancers. In the previous study of the whole genome sequencing (WGS), we found some mutations of TP53 DBD in esophageal squamous cell carcinoma (ESCC) clinical samples. We focused on two high-frequent mutations TP53 p.G245C and TP53 p.R273H and investigated their oncogenic roles in ESCC cell lines, p53-defective cell lines H1299 and HCT116 p53?/?.

Results

MTS and colony formation assays showed that mutant TP53 G245C and R273H increased cell vitality and proliferation. Flow cytometry results revealed inhibition of ultraviolet radiation (UV)- and ionizing radiation (IR)- induced apoptosis and disruption of TP53-mediated cell cycle arrest after UV, IR and Nocodazole treatment. Transwell assays indicated that mutant TP53 G245C and R273H enhanced cell migration and invasion abilities. Moreover, western blot revealed that they were able to suppress the expression of TP53 downstream genes in the process of apoptosis and cell cycle arrest induced by UV, which suggests that these two mutations can influence apoptosis and growth arrest might be due, at least in part, to down-regulate the expression of P21, GADD45α and PARP.

Conclusions

These results indicate that mutant TP53 G245C and R273H can lead to more aggressive phenotypes and enhance cancer cell malignancy, which further uncover TP53 function in carcinogenesis and might be useful in clinical diagnosis and therapy of TP53 mutant cancers.