Influence of Rapeseed Cake on Iron Plaque Formation and Cd Uptake by Rice (Oryza sativa L.) Seedlings Exposed to Excess Cd.

A soil spiking experiment at two Cd levels (0.72 and 5.20 mg kg-1) was conducted to investigate the effects of rapeseed cake (RSC) at application rates of 0%, 0.75%, 1.5%, and 3.0% (w/w) on iron plaque formation and Cd uptake by rice (Oryza sativa L.) seedlings. The use of RSC did result in a sharp decrease in soil bioavailability of Cd and a significant increase in rice growth, soil pH and organic matter. Application of RSC increased the amount of iron plaque formation and this effectively inhibited the uptake and translocation of Cd into the rice seedlings. RSC was an effective organic additive for increasing rice growth and reducing Cd uptake by rice plant, simultaneously. These results could be used as a reference for the safety use of Cd polluted paddy soil.

Transforming growth factor-ß1-induced epithelial-mesenchymal transition in human esophageal squamous cell carcinoma via the PTEN/PI3K signaling pathway.

Epithelial-mesenchymal transition (EMT) is a crucial step for the invasive and metastatic properties of malignant tumor cells during tumor progression. Numerous signaling pathways are involved in the process of EMT in cancer, such as the EMT-inducing signal transforming growth factor (TGF)-ß and the recently demonstrated PTEN/PI3K signaling pathway. To date, no data have been reported concerning the influence of PTEN/PI3K signaling pathway on EMT in human esophageal squamous cell carcinoma (ESCC) and how TGF-ß1 and PTEN/PI3K act through multiple interconnected signaling pathways to trigger events associated with EMT and tumor progression. Our data showed that the PTEN/PI3K pathway was active in human ESCC tissues in vivo, particularly in ESCC with decreased E-cadherin and increased vimentin protein expression, poor differentiation, deep invasion and lymph node metastasis, which are responsible for EMT and tumor progression. In addition, in the human ESCC cell line (EC-1) in vitro, TGF-ß1 treatment markedly induced EMT, including morphological alterations, a decrease of E-cadherin and an increase of vimentin levels and enhanced mobility and invasiveness. Furthermore, the PTEN/PI3K pathway was also activated in the process of TGF-ß1-induced EMT in EC-1 cells in vitro, whereas inhibition of the PTEN/PI3K pathway by using pcDNA3.1 PTEN partially blocked TGF-ß1-induced EMT and reduced mobility and invasiveness. These studies suggest that TGF-ß1 and the PTEN/PI3K signaling pathway contribute to EMT and the PTEN/PI3K signaling pathway is a key regulator of TGF-ß1­induced EMT in ESCC. Disruption of the PTEN/PI3K pathway involved in TGF-ß1-induced EMT may provide possible routes for therapeutic intervention to ESCC.

Relationship between TWIST expression and epithelial-mesenchymal transition of oesophageal squamous cell carcinoma.

We have investigated mRNA and protein expression of TWIST, Vimentin and E-cadherin in ESCC (oesophageal squamous cell carcinoma) and explored their relationship with tumour's infiltration and metastasis. RT-PCR (reverse transcriptase-PCR) was used to evaluate mRNA expression of TWIST, E-cadherin and Vimentin in 40 cases of ESCC. The protein expression of the genes was examined by immunohistochemical staining in each specimen. Expression of TWIST, E-cadherin and Vimentin mRNA and protein with clinicopathologic parameters were analysed. mRNAs of TWIST, Vimentin and E-cadherin were expressed in 75, 55 and 35% respectively of ESCC, i.e. significantly different from that in normal oesophageal mucosa (15, 0 and 85% respectively; P<0.01). In ESCC with LN (lymph node) metastasis, expression of TWIST and Vimentin mRNA, but not E-cadherin mRNA was significantly higher (100 and 83%) than in ESCC without LN metastasis (64 and 43%, P=0.018) respectively. Levels of mRNA expression of the 3 genes followed similar patterns to their above-mentioned frequencies. Protein expression of TWIST, E-cadherin and Vimentin were observed in 70, 35 and 50% respectively of ESCC, which were significantly different from normal mucosa (15, 80 and 0%; P<0.001). In ESCC with LN metastasis, protein expression of TWIST and Vimentin, but not E-cadherin, were significantly higher (100 and 75%) than in ESCC without LN metastasis (61 and 39%). Protein expression of TWIST was positively correlated with Vimentin (r=0.327, P=0.039), but negatively correlated with E-cadherin (r= -0.633, P=0.000). Thus, both mRNAs and proteins of TWIST and Vimentin were significantly overexpressed in ESCC, especially ESCC with LN metastasis. The mRNA and protein of E-cadherin were down-regulated in ESCC. These results suggest potential roles of TWIST as the promoter of tumour invasion and metastasis associated with down-regulation of E-cadherin.

[Critical collapse pressure of gas vesicles in six strains of cyanobacteria].

Two methods including filtration (vacuity is 0.02 MPa) and centrifugation ( < 500 r/min) were applied to concentrate algal biomass, and capillary compression tube and the concentrated algae suspensions, critical pressure distribution of gas vesicles in six cyanobacteria were also investigated. The results showed that unicellular Microcystis aeruginosa cells couldn't be concentrated effectively by filtration or centrifugation, but colony of Microcystis wesenbergii and Microcystis flosaquae, and filament of Planktothrix mougeotii could be concentrated by centrifugation and filtration respectively. Both filtration and centrifugation had a negligibly impact on gas vesicles content of cells, and the loss of gas vesicles was lower than 7%. The mean critical pressure values of five strains Microcystis were very close, which ranged from 0.64 to 0.67 MPa, and the mean critical pressure of P. mougeotii was 0.715 MPa. All of the six cyanobacteria were isolated from three shallow lakes, and their mean critical pressure values were lower than those cyanobacteria that inhabit in deep lakes or reservoirs. At the same condition of illumination density and temperature, turgor pressures of two unicellular Microcystis were higher than those of colonial Microcystis.

[Effects of EDTA and iron on growth and competition of Microcystis aeruginosa and Scenedesmus quadricauda].

Not only population density of phytoplankton but also its community structure were influenced by iron limitation. The growth and competition of a cyanobacterium Microcystis aeruginosa and a green alga Scenedesmus quadricauda at different iron and EDTA concentrations were investigated using batch cultures. The results showed that the growth of M. aeruginosa was significantly inhibited whereas S. quadricauda wasn't when EDTA at high concentrations (> or = 13.5 micromol/L), and consequently, it favored the dominance of S. quadricauda. Moreover, increasing iron concentration from 3 micromol/L to 18 micromol/L could greatly alleviate the growth inhibition of M. aeruginosa while increasing concentration of other microelements e.g. B, Mn, Zn, Cu, Mo didn't. These results suggest that high EDTA concentration decreases iron availability for M. aeruginosa, but not for S. quadricauda. The reason that the two algae respond to high EDTA concentrations differently is that their adsorption strategies for iron should be different.