3,3'-OH curcumin causes apoptosis in HepG2 cells through ROS-mediated pathway.

In this paper, we synthesized a series of curcumin analogs and evaluated their cytotoxicity against HepG2 cells. The results exhibited that the hydroxyl group at 3,3'-position play an essential role in enhancing their anti-proliferation activity. More importantly, 3,3'-hydroxy curcumin (1b) caused apoptosis in HepG2 cells with the ROS generation, which may be mainly composed of hydroxyl radicals (HO) and H2O2. The more cytotoxic activity and ROS-generating ability of 1b may be due to the more stable in (RPMI)-1640 medium and more massive uptake than curcumin. Then the generation of ROS can disrupt the intracellular redox balance, induce lipid peroxidation, cause the collapse of the mitochondrial membrane potential and ultimately lead to apoptosis. The results not only suggest that 3,3'-hydroxy curcumin (1b) may cause HepG2 cells apoptosis through ROS-mediated pathway, but also offer an important information for design of curcumin analog.

Fluorescein-labeled "arch-like" DNA probes for electrochemical detection of DNA on gold nanoparticle-modified gold electrodes.

In the present study, a gold nanoparticle-modified gold electrode (nanogold electrode) was used to develop a novel fluorescein electrochemical DNA biosensor based on a target-induced conformational change. The nanogold electrode was obtained by electrodepositing gold nanoparticles onto a bare gold electrode. This modification not only immobilized probe oligonucleotides, but also adsorbed fluorescein onto the surface of the gold nanoparticles to form an "arch-like" structure. This article compares the electrochemical signal changes caused by the hybridization of "arch-like" DNA on nanogold electrode and linear DNA on bare gold electrode. The results showed that the adsorption effect of nanogold can enhance the sensitivity of the sensor. The linear range of target ssDNA is from 2.0 × 10(-9)M to 2.0 × 10(-8)M with a correlation coefficient of 0.9956 and detection limit (3σ) of 7.10 × 10(-10)M. Additionally, the specificity and hybridization response of this simple sensor were investigated.

Overexpression of CaHSP26 in transgenic tobacco alleviates photoinhibition of PSII and PSI during chilling stress under low irradiance.

A sweet pepper cDNA clone, CaHSP26 encoding the chloroplast (CP)-localized small heat shock protein (sHSP), was isolated and characterized with regard to its sequence, response to various temperatures and function in transgenic tobacco plants. The deduced amino acid sequence contained three highly conserved regions, showing high identities with other plant sHSPs. Expression of the CaHSP26 gene showed that the mRNA accumulation of CaHSP26 was induced by heat stress. Higher transcript levels were observed when sweet pepper leaves were treated at 42 degrees C for 3h. However, the expression of the CaHSP26 gene was not induced by chilling stress (4 degrees C) in the absence of heat shock (HS). But the transcripts were still detected at 48h at 4 degrees C after HS while not at 25 degrees C. The photochemical efficiency of PSII (Fv/Fm) and the oxidizable P700 in transgenic tobacco overexpressing CaHSP26 were higher than that in wild type tobacco during chilling stress under low irradiance. These results suggest that CP sHSP protein plays an important role in protection of PSII and PSI during chilling stress under low irradiance.

Analysis of amylose accumulation during seed development in maize.

Starch, which includes amylose and amylopectin, is the most important component in maize (Zea mays L.) seeds. The accumulation of amylose in maize seeds was examined in this study. The percentage of amylose content gradually increased in seeds from day 10 to day 25 after pollination, which is consistent with the changes of GBSS activity. The transcripts of GBSSI were detected in both the endosperm and embryo of wild-type maize. However, its transcripts, GBSS activity, and amylose were not detected in either the endosperm or embryo of waxy maize. These results indicate that the accumulation of amylose is controlled by GBSSI expression in the seeds of maize.

[cDNA cloning and expression of a cytosolic small heat shock protein gene (CaHSP18) from Capsicum annuum].

Full length 779 bp cytosolic clsss I sHSP cDNA was cloned from heat-shocked sweet pepper leaves using a PCR approach with degenerate primers designed from conserved motifs found in a number of plant cytosolic clsss I sHSP genes, named CaHSP18. Its accession number is AY284925. CaHSP18 was high identified with Nicotiana tabacum (Fig.1). A multi-gene family was found in sweet pepper genomic DNA by Southern-blot analysis (Fig.3). Northern blot revealed that the expression of CaHSP18 in sweet pepper was induced by heat treatment and was significantly different between different tissues (Fig.4). The transcription of CaHSP18 in leaves and stems were higher than those in roots. The expression of CaHSP18 could be detected after chilling treatment at 4 degrees C for 2 d. Recombinant CaHSP18 was overexpressed in Escherichia coli to study its possible function under heat and chilling stress. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of cell lysates suggested that CaHSP18 was expressed in Escherichia coli (Fig.6). The growth of wild type and transformed cells was similar at 37 degrees C (Fig. 5). Upon transfer from 37 degrees C to 50 degrees C, a temperature known to cause cell autolysis, those cells that accumulated CaHSP18 showed improved viability compared with the control lines (Fig.7). To test the hypothesis that sHSPs may be involved in protection against chilling stress, the viability of recombinant cells at 4 degrees C was studied. The sweet pepper CaHSP18 significantly enhanced cell survivability (Fig.8). These results indicate that plant cytosolic clsss I sHSP have protective functions not only against heat stress but also against chilling stress.