Tumor spectrum, tumor latency and tumor incidence of the Pten-deficient mice

Background

Pten functionally acts as a tumor suppressor gene. Lately, tissue-specific ablation of Pten gene in mice has elucidated the role of Pten in different tumor progression models. However, a temporally controlled Pten loss in all adult tissues to examine susceptibility of various tissues to Pten-deficient tumorigenesis has not been addressed yet. Our goal was to explore the genesis of Pten-deficient malignancies in multiple tissue lineages of the adult mouse.

Methods and Findings

We utilized an inducible Cre/loxP system to delete Pten exon 5 in the systemic organs of ROSA26 (R26)-CreER^T;Pten^fx/fx mice. On reaching 45 weeks 4OHT-induced Pten loss, we found that the R26-CreER^T;Pten^fx/fx mice developed a variety of malignancies. Overall tumor mean latency was 17 weeks in the Pten-deficient mice. Interestingly, mutant females developed malignancies more quickly at 10∼11 weeks compared with a tumor latency of 21 weeks for mutant males. Lymphoma incidence (76.9% in females; 40.0% in males) was higher than the other malignancies found in the mutant mice. Mutant males developed prostate (20.0%), intestinal cancer (35.0%) and squamous cell carcinoma (10.0%), whereas the mutant females developed squamous cell carcinoma (15.4%) and endometrial cancer (46.1%) in addition to lymphomas. Furthermore, we tested the pharmacological inhibition of the PTEN downstream effectors using {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 on Pten-deficient prostate hyperplasia. Our data revealed that, indeed, the prostate hyperplasia resulting from the induced Pten loss was significantly suppressed by {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 (p = 0.007).

Conclusions

Through monitoring a variety of Pten-deficient tumor formation, our results revealed that the lymphoid lineages and the epithelium of the prostate, endometrium, intestine and epidermis are highly susceptible to tumorigenesis after the Pten gene is excised. Therefore, this R26-CreER^T; Pten^fx/fx mouse model may provide an entry point for understanding the role of Pten in the tumorigenesis of different organs and extend the search for potential therapeutic approaches to prevent Pten-deficient malignancies.     

伤胁迫对蚕豆叶片中茉莉酸分布的影响

在植物应对伤害等环境刺激的反应中,已知茉莉酸(JA)作为一种重要的信号分子在植物体内长距离运输,但目前对JA的细胞和亚细胞定位知之甚少。本研究用免疫荧光显微镜技术和免疫胶体金电镜技术证明茉莉酸分布在蚕豆叶片叶肉细胞的叶绿体、表皮细胞的细胞壁、保卫细胞的细胞壁、细胞质、叶绿体和细胞核上。其中保卫细胞的叶绿体和细胞核是JA分布的主要场所。叶片的局部灼伤可提高JA在质外体和气孔保卫细胞中的水平。由此推测,伤胁迫下JA分配的改变可能与植物体防御反应密切相关,并参与了对气孔运动的调控。     

Determination of triazines in infant nutrient cereal-based foods by pressurized microwave-assisted extraction coupled with high-performance liquid chromatography-mass spectrometry

A method for determining triazine herbicides in infant nutrient cereal-based foods by pressurized microwave-assisted extraction (PMAE), coupled with high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI/MS), is described. The key parameters of PMAE, including extraction solvent, extraction time and temperature, were optimized. The isolation of the target compounds from the matrix was found to be efficient when 2 g of nutrient cereal samples was extracted with 20 mL of methanol for 10 min at 105 degrees C. Final determination was accomplished by HPLC-ESI/MS. The recoveries from 66.2 to 88.6% were obtained for three compounds at fortification levels (5-500 microg kg(-1)) with relative standard deviations (R.S.D.) 相似文献   

The Effect of Glycerol on Molecular Mobility in Amorphous Sucrose Detected by Phosphorescence of Erythrosin B

Luminescence from the triplet probe erythrosin B provides spectroscopic characteristics such as emission energy and lifetime that are sensitive to molecular mobility of the local solvent environment. This study investigated how variation in glycerol content influences the properties of an amorphous sucrose matrix by monitoring phosphorescence of erythrosin B over the temperature range from 5 to 100°C. Emission energy, lifetime, and red-edge excitation data revealed that glycerol affected the mobility of amorphous sucrose matrix primarily through plasticization when the mole ratio of glycerol/sucrose was above 0.27, resulting in a decrease in emission energy (ν _p), lifetime (τ) and energy difference (Δν _P) with excitation at the absorption peak and red edge and an increase in the nonradiative, collisional quenching rate k _TS0. At mole ratios ≤0.27 and at temperatures below the matrix T _g, glycerol exhibited an “antiplasticization” effect, as indicated by higher values of emission energy, lifetime, and energy difference and lower values of the matrix collisional quenching rate. Changes in the distribution of emission energy (emission bandwidth) and lifetime, and variation in the emission lifetime vs wavelength showed that glycerol reduced the spectral heterogeneity. These data illustrate the complex effect of a hydrogen bonding solute on the mobility of an amorphous, hydrogen bonded sugar matrix.     

A hybrid boronate affinity probe for the selective detection of cis-diol containing compounds in tea beverages

UiO-66-NH₂ nanocomposite was post-modified with 4-mercaptophenylboronic acid (MPBA) by the method of in situ hybridization reaction. The hybrid boronate affinity material UiO-NH₂@P (TEPIC-co-MPBA) was characterized by scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. The material was applied as fluorescent probe for the detection of cis-diol containing compounds based on the boronate affinity mechanism, and exhibited high specific selectively. The proposed method exhibited good linearity for the detection of catechol in the range of 0.50 to 8.00 μg ml⁻¹. The detection limit was 0.13 μg ml⁻¹. The tactic was successfully applied to analyze the total polyphenols in tea beverages for catechol, and relative recovery was in 98.86–106.00%. Therefore, this work provided a promising strategy for the recognition of cis-diol containing compounds.     

Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies. However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China. We conducted a spatial phylogenetic analysis of the Chinese angiosperm flora at the generic level to identify centers of neo- and paleo-endemism. Our results indicate that: (i) the majority of grid cells in China with significantly high phylogenetic endemism (PE) were located in the mountainous regions; (ii) four of the nine centers of endemism recognized, located in northern and western China, were recognized for the first time; (iii) arid and semiarid regions in Northwest China were commonly linked to significant PE, consistent with other spatial phylogenetic studies worldwide; and (iv) six high-priority conservation gaps were detected by overlaying the boundaries of China's nature reserves on all significant PE cells. Overall, we conclude that the mountains of southern and northern China contain both paleo-endemics (ancient relictual lineages) and neo-endemics (recently diverged lineages). The areas we highlight as conservation priorities are important for broad-scale planning, especially in the context of evolutionary history preservation.     

Apoptosis in HepaRG and HL-7702 cells inducted by polyphyllin II through caspases activation and cell-cycle arrest

Rhizoma Paridis, a traditional Chinese medicine, has shown promise in cancer prevention and therapy. Polyphyllin II is one of the most significant saponins in Rhizoma Paridis and it has toxic effects on kinds of cancer cells. However, our results in this study proved that the polyphyllin II has hepatotoxicity in vitro through caspases activation and cell-cycle arrest. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide results indicated polyphyllin II inhibited proliferation, induced apoptosis in HepaRG cells and HL-7702 cells and showed a concentration and time-dependent. Then, we selected the innovative cell model-HepaRG cells to explore the mechanism of hepatotoxicity. Our data showed the reactive oxygen species (ROS) increased and the mitochondrial membrane potential decreased in HepaRG cells after administration of polyphyllin II. Besides, with the increase of concentration, the release of lactate dehydrogenase increased and the S phase of the cell cycle was arrested. Nevertheless, when pretreatment with antioxidant N-acetylcysteine, apoptotic cells decreased significantly, inhibited the production of ROS and improved the decrease of membrane potential in HepaRG cells. Moreover, polyphyllin II treatment increased levels of Fas, Bax, cytochrome c, activated caspase-3, -8, -9, cleaved poly(ADP-ribose) polymerase and decreased Bcl-2 expression levels. Finally, we identified two signal pathways of apoptosis induced by polyphyllin II including the death receptor pathway and the mitochondria pathway. This study confirmed the hepatotoxicity of the polyphyllin II in vitro, which has never been discovered and gave a wake-up call for the clinical application of Rhizoma Paridis.     

假单胞菌Pseudomonas fluorescens Pf0-1中转录调控因子SpfB负调控DNA磷硫酰化修饰

[目的]DNA磷硫酰化修饰是DNA骨架上非桥接的氧原子以序列选择性和R-构型被硫取代的一种新型DNA修饰。目前,磷硫酰化修饰在多种细菌、古生菌以及人类致病菌中多有发现,但其分子调控机制尚不清楚。为了全面解析磷硫酰化修饰的调控机制,本文选择荧光假单胞菌Pf0-1为研究对象,开展了其DNA磷硫酰化修饰的调控机制研究。[方法]首先,构建了spfB基因缺失和回补菌株,使用碘能特异性断裂磷硫酰化修饰DNA的方法,研究了该基因缺失对修饰表型的影响。利用cDNA在相邻同方向的基因间隔区进行PCR,确定了磷硫酰化修饰基因簇spfBCDE内的共转录单元。通过荧光定量RT-PCR,分析了spfB基因缺失突变株中磷硫酰化修饰基因的转录量。利用异源表达并纯化得到的重组蛋白SpfB进行了体外功能研究。通过EMSA实验,验证了SpfB蛋白具有与spfB启动子序列结合活性。通过DNase I footprinting实验,精确定位了SpfB蛋白与DNA结合序列。[结果]spfB基因的缺失加剧了磷硫酰化修饰DNA断裂所致电泳条带弥散的表型,spfB基因的回补能够恢复该表型,证明spfB基因负调控磷硫酰化修饰。鉴定了spf基因簇中只含有1个共转录单元,且该共转录单元在△spfB突变株中转录水平明显上升。通过EMSA和DNase I footprint实验,检测了SpfB蛋白与磷硫酰化修饰基因spfBCDE的启动子区域5''-TGTTTGT-3''相结合。[结论]SpfB作为转录调控因子负调控磷硫酰化修饰基因spfBCDE的表达,为解析磷硫酰化修饰的调控机制和全面理解基因组上的部分修饰特征奠定了基础。