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Biomedical subjects

Peng Jiang

Publications and source records attributed to Peng Jiang.

23 records · Page 2Linked to original sources
PubMed2005

Cloning and characterization of beta-carotene ketolase gene promoter in Haematococcus pluvialis.

The unicellular green alga Haematococcus pluvialis accumulates a highly valuable ketocarotenoid, astaxanthin, under various environmental stresses. beta-carotene ketolase (BKT) plays a key role in astaxanthin biosynthesis in H. pluvialis. In this paper, an approximate 700 bp 5'-flanking region of the bkt gene containing a putative promoter was cloned through walking upstream. The results of the sequence analysis showed that this bkt 5'-flanking region might have cis-acting elements such as sterol regulatory element (SRE-1)-like motifs, the C-repeat/dehydration responsive element (DRE) and al-3 proximal element (APE)-like motifs, except for typical TATA and CCAAT boxes. The results of the beta-galactosidase assay and the transient expression of lacZ driven by a series of sequential deletions revealed that a minimal promoter-like region might exist from -630 to -408 bp, and the highest promoter activity was observed to span the positions from -630 to -308 bp. The results of the site-directed mutagenesis of a C-repeat/DRE and two APE-like motifs in a promoter-like region (-630 to -308 bp) suggested that two APE-like motifs might be essential for transcriptional control of the bkt gene.

Bacterial Proteins↗
PubMed2005

Establishment of a micro-particle bombardment transformation system for Dunaliella salina.

In this study, we chronicle the establishment of a novel transformation system for the unicellular marine green alga, Dunaliella salina. We introduced the CaMV35S promoter-GUS construct into D. salina with a PDS1000/He micro-particle bombardment system. Forty eight h after transformation, via histochemical staining, we observed the transient expression of GUS in D. salina cells which had been bombarded under rupture-disc pressures of 450 psi and 900 psi. We observed no GUS activity in either the negative or the blank controls. Our findings indicated that the micro-particle bombardment method constituted a feasible approach to the genetic transformation of D. salina. We also conducted tests of the cells' sensitivity to seven antibiotics and one herbicide, and our results suggested that 20 microg/ml of Basta could inhibit cell growth completely. The bar gene, which encodes for phosphinothricin acetyltransferase and confers herbicide tolerance, was introduced into the cells via the above established method. The results of PCR and PCR-Southern blot analyses indicated that the gene was successfully integrated into the genome of the transformants.

Aminobutyrates↗
PubMed2004

Large-scale fabrication of wafer-size colloidal crystals, macroporous polymers and nanocomposites by spin-coating.

This paper reports a simple spin-coating technique for rapidly fabricating three types of technologically important materials--colloidal crystal, macroporous polymer, and polymeric nanocomposite, each with high crystalline qualities and wafer-scale sizes. Dispersion of monodisperse silica colloids in triacrylate monomers is spin-coated onto a variety of substrates. Shear-induced ordering and subsequent polymerization lead to the formation of three-dimensionally (3D) ordered colloidal crystals trapped inside a polymer matrix. The thickness of as-synthesized colloidal crystal-polymer nanocomposite is highly uniform and can be controlled simply by changing the spin speed and time. Selective removal of the polymer matrix and silica spheres lead to the formation of large-area colloidal crystals and macroporous polymers, respectively. The wafer-scale process is compatible with standard semiconductor microfabrication, as multiple micrometer-sized patterns can be created simultaneously for potential device applications. Normal-incidence transmission spectra in the visible and near-infrared regions show distinct peaks due to Bragg diffraction from 3D ordered structures. The spin-coating process opens a new route to the fundamental studies of shear-induced crystallization, melting and relaxation.

Colloids↗
PubMed2004

Machinable long PVP-stabilized silver nanowires.

PVP-capped silver nanowires with a diameter range from 150 to 200 nm and a length range from 50 to 100 microm have been synthesized in large quantity by using a soft-template liquid-phase method. The so-obtained longer and thicker metallic nanowires exhibit fivefold-twinned structures bound by five [1 0 0] wall-planes and two spearlike ends around five [1 1 1] facets. X-ray photoelectron spectroscopy (XPS) investigations show that a strong interaction exists between the carboxyl oxygen atom (C=O) of PVP and the Ag core interface. The PVP-capped Ag nanowires can either self-assemble into ordered raft structures or form a complicated network, depending on the dispersive solvent employed. In addition, the Ag nanowires can also be specifically bent into various angles, demonstrating their excellent mechanical stability.

Journal Article↗