HOP/OB1/NECC1 promoter DNA is frequently hypermethylated and involved in tumorigenic ability in esophageal squamous cell carcinoma

Promoter DNA hypermethylation with gene silencing is a common feature of human cancer, and cancer-prone methylation is believed to be a landmark of tumor suppressor genes (TSG). Identification of novel methylated genes would not only aid in the development of tumor markers but also elucidate the biological behavior of human cancers. We identified several epigenetically silenced candidate TSGs by pharmacologic unmasking of esophageal squamous cell carcinoma (ESCC) cell lines by demethylating agents (5-aza-2'-deoxycitidine and trichostatin A) combined with ESCC expression profiles using expression microarray. HOP/OB1/NECC1 was identified as an epigenetically silenced candidate TSG and further examined for (a) expression status, (b) methylation status, and (c) functional involvement in cancer cell lines. (a) The HOP gene encodes two putative promoters (promoters A and B) associated with two open reading frames (HOPalpha and HOPbeta, respectively), and HOPalpha and HOPbeta were both down-regulated in ESCC independently. (b) Promoter B harbors dense CpG islands, in which we found dense methylation in a cancer-prone manner (55% in tumor tissues by TaqMan methylation-specific PCR), whereas promoter A does not harbor CpG islands. HOPbeta silencing was associated with DNA methylation of promoter B in nine ESCC cell lines tested, and reactivated by optimal conditions of demethylating agents, whereas HOPalpha silencing was not reactivated by such treatments. Forced expression of HOP suppressed tumorigenesis in soft agar in four different squamous cell carcinoma cell lines. More convincingly, RNA interference knockdown of HOP in TE2 cells showed drastic restoration of the oncogenic phenotype. In conclusion, HOP is a putative TSG that harbors tumor inhibitory activity, and we for the first time showed that the final shutdown process of HOP expression is linked to promoter DNA hypermethylation under the double control of the discrete promoter regions in cancer.     

Development of an expressed sequence tag (EST) resource for wheat (Triticum aestivum L.): EST generation, unigene analysis, probe selection and bioinformatics for a 16,000-locus bin-delineated map

This report describes the rationale, approaches, organization, and resource development leading to a large-scale deletion bin map of the hexaploid (2n = 6x = 42) wheat genome (Triticum aestivum L.). Accompanying reports in this issue detail results from chromosome bin-mapping of expressed sequence tags (ESTs) representing genes onto the seven homoeologous chromosome groups and a global analysis of the entire mapped wheat EST data set. Among the resources developed were the first extensive public wheat EST collection (113,220 ESTs). Described are protocols for sequencing, sequence processing, EST nomenclature, and the assembly of ESTs into contigs. These contigs plus singletons (unassembled ESTs) were used for selection of distinct sequence motif unigenes. Selected ESTs were rearrayed, validated by 5′ and 3′ sequencing, and amplified for probing a series of wheat aneuploid and deletion stocks. Images and data for all Southern hybridizations were deposited in databases and were used by the coordinators for each of the seven homoeologous chromosome groups to validate the mapping results. Results from this project have established the foundation for future developments in wheat genomics.     

尖孢镰孢一新硝酸盐营养突变类型与营养体亲和性

从73个尖孢镰孢(Fusarium oxysporum)不同专化型菌株上获得684个硝酸盐营养突变株(nit mutant)。作相关氮源利用试验及亚硝酸反应后,鉴定出一新硝酸盐营养突变类型:亚硝酸盐还原酶结构基因类型,命名为nit8,占总突变株的6.7%。同时被鉴别的还有nit1、nit3和Nit M三种突变类型,它们分别占突变株总数的81.0%,3.8%和8.5%。此外,首次引入一种亚硝酸反应在这类研究中的应用,还提出了互补指数概念与公式来表示nit突变株营养体之间亲和的能力。     

Photochemistry of dyes and fluorochromes used in biology and medicine: some physicochemical background and current applications

An overview of the basic principles of photochemistry is presented to facilitate discussion of fluorescence, quenching and quantum yields. These topics in turn provide the foundation for an account of fluorescence spectroscopy and its application to microscopy. A brief overview of light microscopy and the application of fluorescence microscopy is given. The influences of molecular features, such as aromatic character and substitution patterns, on color and fluorescence are described. The concept of color fading is considered with particular reference to its effect on microscopic preparations. A survey of representative fluorescent probes is provided, and their sensitivity, application, and limitations are described. The phototoxicity of fluorescent molecules is discussed using biomembranes and DNA as examples of targets of toxicity. Photodynamic therapy, a relatively new clinical application of phototoxicity, is described. Both anticancer and antimicrobial applications are noted, and an assessment is given of the current ideas on the ideal physicochemical properties of the sensitizing agents for such applications.     

常用食品防腐剂抗菌作用的研究

采用杯碟法和琼脂平板点种法分别测定２０种常用食品防腐剂对３０株菌的抑菌圈直径和最低抑菌浓度,借此判断药剂抗菌力的大小。实验结果表明,在所测２０种防腐剂中,对细菌抑制力最强者是乙酸,对霉菌和酵母菌抑制力最强者是富马酸二甲酯。     

A Src inhibitor regulates the cell cycle of human pluripotent stem cells and improves directed differentiation

Driving human pluripotent stem cells (hPSCs) into specific lineages is an inefficient and challenging process. We show that a potent Src inhibitor, PP1, regulates expression of genes involved in the G1 to S phase transition of the cell cycle, activates proteins in the retinoblastoma family, and subsequently increases the differentiation propensities of hPSCs into all three germ layers. We further demonstrate that genetic suppression of Src regulates the activity of the retinoblastoma protein and enhances the differentiation potential of hPSCs across all germ layers. These positive effects extend beyond the initial germ layer specification and enable efficient differentiation at subsequent stages of differentiation.     

Metabolism of copper and zinc in the liver and bone of the perinatal guinea-pig

Hepatic copper concentration in the guinea-pig increased markedly during the second-half of gestation, attaining a maximum shortly after birth; thereafter, concentration declined rapidly during the neonatal period. Changes in perinatal hepatic copper concentrations paralleled the binding of copper to a cytosolic metallothionein-like component, and the loss of hepatic copper in the neonates coincided with increases in serum copper concentrations. Zinc concentrations of the perinatal liver were low and showed no dramatic developmental changes. The humerus showed striking increases in zinc concentration with gestational age, attaining peak concentration before term and a marked depletion of tissue zinc during the neonatal period.     

The farnesoid X receptor -1G>T polymorphism influences the lipid response to rosuvastatin

The bile acid-activated nuclear receptor farnesoid X receptor (FXR) plays an important role in lipid and glucose metabolism, and in addition, it regulates multiple drug transporters involved in statin disposition. We examined whether a functional single nucleotide polymorphism (SNP) in FXR (-1G>T) influenced the lipid-lowering effect of rosuvastatin. In 385 Chinese patients with hyperlipidemia who had been treated with rosuvastatin 10 mg daily for at least 4 weeks, the association between the FXR -1G>T SNP and lipid response to rosuvastatin was analyzed. The FXR -1G>T SNP was not associated with baseline lipids but was significantly associated with the LDL cholesterol (LDL-C) and total cholesterol response to rosuvastatin. Carriers of the T-variant allele (GT+TT = 68+3) had 4.4% (95% CI: 1.2, 7.5%, P = 0.006) and 2.6% (95% CI: 0.3, 5.0%; P < 0.05) greater reductions in LDL-C and total cholesterol, respectively, compared with those with homozygous wild-type alleles. The association between the FXR polymorphism and the LDL-C response to rosuvastatin remained significant after adjusting for other covariants. This association of the variant allele of the FXR -1G>T polymorphism with a greater LDL-C response to rosuvastatin may suggest that this polymorphism influences the expression of the hepatic efflux transporters involved in biliary excretion of rosuvastatin.