Construction of an alternative glycerol-utilization pathway for improved ß-carotene production in Escherichia coli.

Glycerol, which is an inevitable by-product of biodiesel production, is an ideal carbon source for the production of carotenoids due to its low price, good availability and chemically reduced status, which results in a low requirement for additional reducing equivalents. In this study, an alternative carbon-utilization pathway was constructed in Escherichia coli to enable more efficient ß-carotene production from glycerol. An aldehyde reductase gene (alrd) and an aldehyde dehydrogenase gene (aldH) from Ralstonia eutropha H16 were integrated into the E. coli chromosome to form a novel glycerol-utilization pathway. The ß-carotene specific production value was increased by 50% after the introduction of alrd and aldH. It was found that the glycerol kinase gene (garK), alrd and aldH were the bottleneck of the alternative glycerol metabolic pathway, and modulation of garK gene with an mRS library further increased the ß-carotene specific production value by 13%. Finally, co-modulation of genes in the introduced aldH-alrd operon led to 86% more of ß-carotene specific production value than that of the strain without the alternative glycerol-utilization pathway and the glycerol-utilization rate was also increased. In this work, ß-carotene production of E. coli was significantly improved by constructing and optimizing an alternative glycerol-utilization pathway. This strategy can potentially be used to improve the production of other isoprenoids using glycerol as a cheap and abundant substrate, and therefore has industrial relevance.

[Construction and targeting study of eukaryotic expression vector modulated by a macrophage-specific promoter].

AIM: To construct a macrophage-specific eukaryotic expression vector and to investigate its expressing specificity. METHODS: Macrophage-specific promoter was synthesized using PCR, and substituted the CMV promoter of eukaryotic expression vector pEGFP-N1 to construct a recombinant vector (pSP-GFP), which were cotransfected with pERFP-N1 vector into different cell lines. The green fluorescent protein (GFP) and red fluorescent protein (RFP) was observed by fluorescence microscopy, and the target specificity of macrophage-specific promoter was judged by comparison of expressed level of GFP and RFP in various cell lines. RESULTS: The macrophage-specific eukaryotic expression vector was successfully constructed, which showed strong activity and specificity only in macrophage cells. CONCLUSION: The constructed pSP-GFP vector was macrophage-specific, which are potential to targeted gene therapy of intracellular bacterial infection.

2-(4-Dimethyl-amino-2-hydroxy-benzoyl)benzoic acid methanol solvate.

In the title compound, C(16)H(15)NO(4)·CH(4)O, the dihedral angle between the benzene rings is 75.21 (5)°. The structure is stabilized by an intra-molecular O-H⋯O inter-action [O⋯O = 2.589 (2) Å]. The solvent mol-ecule links symmetry-related mol-ecules of the complex via hydrogen bonds with O⋯O separations of 2.631 (2) and 2.815 (2) Å. C-H⋯O hydrogen bonds are also present.

A global assembly of cotton ESTs.

Approximately 185,000 Gossypium EST sequences comprising >94,800,000 nucleotides were amassed from 30 cDNA libraries constructed from a variety of tissues and organs under a range of conditions, including drought stress and pathogen challenges. These libraries were derived from allopolyploid cotton (Gossypium hirsutum; A(T) and D(T) genomes) as well as its two diploid progenitors, Gossypium arboreum (A genome) and Gossypium raimondii (D genome). ESTs were assembled using the Program for Assembling and Viewing ESTs (PAVE), resulting in 22,030 contigs and 29,077 singletons (51,107 unigenes). Further comparisons among the singletons and contigs led to recognition of 33,665 exemplar sequences that represent a nonredundant set of putative Gossypium genes containing partial or full-length coding regions and usually one or two UTRs. The assembly, along with their UniProt BLASTX hits, GO annotation, and Pfam analysis results, are freely accessible as a public resource for cotton genomics. Because ESTs from diploid and allotetraploid Gossypium were combined in a single assembly, we were in many cases able to bioinformatically distinguish duplicated genes in allotetraploid cotton and assign them to either the A or D genome. The assembly and associated information provide a framework for future investigation of cotton functional and evolutionary genomics.