锌离子存在下EGCG对前列腺癌细胞生长的影响

本文研究了锌离子存在下EGCG对前列腺癌细胞PC-3生长的影响．研究发现Zn^2＋可以增强EGCG抗癌活性,Zn^2＋存在下。EGCG处理后前列腺癌细胞PC-3克隆形成率显著下降。以RT—PCR、免疫组化方法研究Zn^2＋、EGCG对67kD层粘连蛋白受体（67kD Laminin Receptor,67LR）表达调控,结果表明Znn可通过上调67LR的表达,为EGCG提供更多作用的靶位点,增强EGCG对前列腺癌细胞PC-3的毒性作用。MMP-9是肿瘤侵袭转移过程中关键的基质金属蛋白酶。MMP-9活性与癌细胞的转移潜能密切相关。本文研究发现Zn^2＋、EGCG处理可通过抑制MMP-9活性,降低前列腺癌细胞PC-3的迁移率．其中80umol／LEGCG＋80umol／L Zn^2＋处理24h后显著抑制了PC-3细胞的迁移率。     

Involvement of insulin in early development of mouse one-cell stage embryos

Recent studies have suggested that growth factors and hormones play important roles in cell prolif-eration and differentiation during early embryonic development. In the present study, we examined the expression and localization of insulin in the mouse oocytes and one-cell stage embryos by quantitative ELISA, RT-PCR, Western blot and immunofluorescence. In the mouse oocytes and one-cell stage em-bryos, expression of insulin was uniformly distributed in the cytoplasm. We also examined the expres-sion, activity and localization of mTOR (mammalian target of rapamycin) and p70S6K. The expression of mTOR and p70S6K was not significantly different at the cell cycle of mouse one-cell stage embryos. mTOR and S6K were distributed evenly in the cytoplasm at G1, G2 and M phase phase, but at S phase, the distribution of mTOR and S6K was around the pronucleus. At different phases, the activity of mTOR fluctuated. We also used the PI3K specific inhibitor-Wortmannin to investigate the cleavage rate of eggs. The result showed that the rate obviously decreased. When the mTOR specific inhibitor Rapa-mycin was used, the first mitotic division of the mouse one-cell stage embryo was delayed. These re-sults suggested that insulin was expressed both in mouse oocytes and one-cell stage embryos, and may play functional roles in regulation of mouse early embryogenesis by activating the signal pathway of PI3K/PKB/mTOR/S6K.     

Effect of mammogenic hormones on the expression of FGF7, FGF10 and their receptor in mouse mammary gland

To investigate the regulation of estrogen, progesterone and prolactin stimulating the development of mammary gland, the Kunming mice were used as experimental animals in this study. Through the experiment in vitro, the effect of mammogenic hormones were systematically investigated on expression of FGF7 and FGF10 and their receptor in different periods. The results are as follows: in mammary glands of mice, 17 beta-estradiol increased the expression of FGF7; progesterone did not affect the expression of FGF7; prolactin up-regulated the expression of FGF7 significantly in pregnancy and lactation. 17 beta-estradiol increased the expression of FGF10; progesterone and prolactin reduced the expression of FGF10 significantly in virgin; prolactin significantly increased the expression of FGF10 in pregnancy. When 17 beta-estradiol in the body was in relatively high proportion, it would lower the expression of KGFR; while 17 beta-estradiol in the body was in relatively low proportion, it would increase the expression of KGFR. Low concentration of progesterone increased the expression of KGFR and high progesterone did not affect the expression of KGFR. Prolactin increased the expression of KGFR significantly in pregnancy and lactation.     

Ecological thresholds of Suaeda salsa to the environmental gradients of water table depth and soil salinity

The responses of Suaeda salsa to the environmental gradients of water table depth and soil salinity in the Yellow River Delta, China were analyzed from the aspect of ecological thresholds which were developed from the Gaussian model. Based on the correlation analysis of population biomass, density, height, coverage and abundance of Suaeda salsa, population biomass was selected as the population index for further analysis. The results indicated that the optimum water table depth for the growth of Suaeda salsa was about −0.42 m, the ecological thresholds were from −0.92 m to 0.08 m, and the optimum ecological thresholds were from −0.67 m to −0.17 m. To the soil salinity gradient, the optimum was about 12.71 g/kg, the ecological thresholds were from 5.17 g/kg to 20.25 g/kg, and the optimum ecological thresholds were from 8.94 g/kg to 16.48 g/kg. However, the effect of water-salinity interaction seemed to be important to the growth of Suaeda salsa, which was discussed through analyzing the water table depth-soil salinity relationship and their interactions. By using Ward cluster analysis and Gamma distances, 69 sampling sites were classified into 7 kinds of Suaeda salsa communities. It was found that there was a remarkable response of the community structure of Suaeda salsa to the water table depth and soil salinity gradients, which can be a switchover from xeromorphic and saline-alkali plants to limnophytes, and vice versa.     

Changes in landscape pattern of alpine wetlands on the Zoige Plateau in the past four decades

Based on RS, GIS and Apack software, the indices of landscape pattern such as landscape area index, landscape diversity index and landscape fragmentation index were chosen in order to describe changes in the spatial pattern of alpine wetland landscape on the Zoige Plateau during 1966–2000. Results showed that alpine wetland landscape was characteristic of marsh wetlands, which had the biggest patch number and the largest area. The alpine wetland landscape had higher spatial heterogeneity. The largest area appeared in Zoige County with the highest wetland ratio; comparatively, Aba County and Luqu County had much lower wetland ratio. The total area of alpine wetland landscape decreased rapidly during 1966–1986, but it began to increase after 1986. The wetland landscape area shrank by 59857.83 hm² during 1966–2000. The alpine wetland landscape showed the characteristics of concentrated distribution in the past four decades, with higher convergence and dominance indices. The centroid of wetland landscape moved 12.54 km in the northwest direction firstly, 11.33 km in the southeast direction, and then 1.1 km in the north direction.     

Cell Surface Sialylation and Fucosylation Are Regulated by L1 via Phospholipase Cγ and Cooperate to Modulate Neurite Outgrowth,Cell Survival and Migration

Background

Cell surface glycosylation patterns are markers of cell type and status. However, the mechanisms regulating surface glycosylation patterns remain unknown.

Methodology/Principal Findings

Using a panel of carbohydrate surface markers, we have shown that cell surface sialylation and fucosylation were downregulated in L1^−/y neurons versus L1^+/y neurons. Consistently, mRNA levels of sialyltransferase ST6Gal1, and fucosyltransferase FUT9 were significantly reduced in L1^−/y neurons. Moreover, treatment of L1^+/y neurons with L1 antibodies, triggering signal transduction downstream of L1, led to an increase in cell surface sialylation and fucosylation compared to rat IgG-treated cells. ShRNAs for both ST6Gal1 and FUT9 blocked L1 antibody-mediated enhancement of neurite outgrowth, cell survival and migration. A phospholipase Cγ (PLCγ) inhibitor and shRNA, as well as an Erk inhibitor, reduced ST6Gal1 and FUT9 mRNA levels and inhibited effects of L1 on neurite outgrowth and cell survival.

Conclusions

Neuronal surface sialylation and fucosylation are regulated via PLCγ by L1, modulating neurite outgrowth, cell survival and migration.     

An analysis of human microRNA and disease associations

It has been reported that increasingly microRNAs are associated with diseases. However, the patterns among the microRNA-disease associations remain largely unclear. In this study, in order to dissect the patterns of microRNA-disease associations, we performed a comprehensive analysis to the human microRNA-disease association data, which is manually collected from publications. We built a human microRNA associated disease network. Interestingly, microRNAs tend to show similar or different dysfunctional evidences for the similar or different disease clusters, respectively. A negative correlation between the tissue-specificity of a microRNA and the number of diseases it associated was uncovered. Furthermore, we observed an association between microRNA conservation and disease. Finally, we uncovered that microRNAs associated with the same disease tend to emerge as predefined microRNA groups. These findings can not only provide help in understanding the associations between microRNAs and human diseases but also suggest a new way to identify novel disease-associated microRNAs.     

Two independent positive feedbacks and bistability in the Bcl-2 apoptotic switch

Background

The complex interplay between B-cell lymphoma 2 (Bcl-2) family proteins constitutes a crucial checkpoint in apoptosis. Its detailed molecular mechanism remains controversial. Our former modeling studies have selected the ‘Direct Activation Model’ as a better explanation for experimental observations. In this paper, we continue to extend this model by adding interactions according to updating experimental findings.

Methodology/Principal Findings

Through mathematical simulation we found bistability, a kind of switch, can arise from a positive (double negative) feedback in the Bcl-2 interaction network established by anti-apoptotic group of Bcl-2 family proteins. Moreover, Bax/Bak auto-activation as an independent positive feedback can enforce the bistability, and make it more robust to parameter variations. By ensemble stochastic modeling, we also elucidated how intrinsic noise can change ultrasensitive switches into gradual responses. Our modeling result agrees well with recent experimental data where bimodal Bax activation distributions in cell population were found.

Conclusions/Significance

Along with the growing experimental evidences, our studies successfully elucidate the switch mechanism embedded in the Bcl-2 interaction network and provide insights into pharmacological manipulation of Bcl-2 apoptotic switch as further cancer therapies.     

Increased frequency of CpG island methylator phenotype and CDH1 methylation in a gastric cancer high-risk region of china

This study aimed to profile the methylation statuses of CDH1/E-cadherin and five CpG island methylator phenotype (CIMP)-associated genes (p16, hMLH1, MINT1, MINT2, and MINT31) in gastric specimens of 47 Dalian long-term residents with and 31 without gastric cancers (GCs). CIMP patterns were classified as CIMP-H with over three methylated genes, CIMP-L with one to two methylated genes, and CIMP-N without methylation. Of 47 GC cases, 24 (51.1%) were CIMP-H, 18 (38.3%) were CIMP-L, and 5 (10.6%) were CIMP-N, whereas 5 of 21 (23.8%) premalignant lesions were CIMP-H and 15 (71.4%) were CIMP-L. CIMP-L was found in 75% (12/16) of GC-adjacent mucosa and in 38.7% (12/31) of mucosa from GC-free patients. CDH1 methylation occurred in 48.9% (23/47) of cancer, in 23.8% (5/21) of premalignant, and in 25% (4/16) of noncancerous tissues and was correlated with patients' age (P = .01), lymph node metastasis, and CIMP severity (P = .000-.028). Our results demonstrated that the frequencies of CIMP-H in Dalian GCs, CIMP-L, and p16 methylation in GC-adjacent tissues and in GC-free mucosa were much higher than those reported previously, indicating the elevated methylation pressure in this GC high-risk region. The close correlation between CDH1 methylation and CIMP severity suggests the necessity of their combination in GC prevention and earlier diagnosis.     

Nitric oxide production from nitrite occurs primarily in tissues not in the blood: critical role of xanthine oxidase and aldehyde oxidase

Recent studies have shown that nitrite is an important storage form and source of NO in biological systems. Controversy remains, however, regarding whether NO formation from nitrite occurs primarily in tissues or in blood. Questions also remain regarding the mechanism, magnitude, and contributions of several alternative pathways of nitrite-dependent NO generation in biological systems. To characterize the mechanism and magnitude of NO generation from nitrite, electron paramagnetic resonance spectroscopy, chemiluminescence NO analyzer, and immunoassays of cGMP formation were performed. The addition of nitrite triggered a large amount of NO generation in tissues such as heart and liver, but only trace NO production in blood. Carbon monoxide increased NO release from blood, suggesting that hemoglobin acts to scavenge NO not to generate it. Administration of the xanthine oxidase (XO) inhibitor oxypurinol or aldehyde oxidase (AO) inhibitor raloxifene significantly decreased NO generation from nitrite in heart or liver. NO formation rates increased dramatically with decreasing pH or with decreased oxygen tension. Isolated enzyme studies further confirm that XO and AO, but not hemoglobin, are critical nitrite reductases. Overall, NO generation from nitrite mainly occurs in tissues not in the blood, with XO and AO playing critical roles in nitrite reduction, and this process is regulated by pH, oxygen tension, nitrite, and reducing substrate concentrations.