Production of β-carotene by metabolically engineered Saccharomyces cerevisiae / 生物工程学报

β-carotene has a wide range of application in food, pharmaceutical and cosmetic industries. For microbial production of β-carotene in Saccharomyces cerevisiae, the supply of geranylgeranyl diphosphate (GGPP) was firstly increased in S. cerevisiae BY4742 to obtain strain BY4742-T2 through over-expressing truncated 3-hydroxy-3-methylglutaryl-CoA reductase (tHMGR), which is the major rate-limiting enzyme in the mevalonate (MVA) pathway, and GGPP synthase (GGPS), which is a key enzyme in the diterpenoid synthetic pathway. The β-carotene synthetic genes of Pantoea agglomerans and Xanthophyllomyces dendrorhous were further integrated into strain BY4742-T2 for comparing β-carotene production. Over-expression of tHMGR and GGPS genes led to 26.0-fold increase of β-carotene production. In addition, genes from X. dendrorhous was more efficient than those from P. agglomerans for β-carotene production in S. cerevisiae. Strain BW02 was obtained which produced 1.56 mg/g (dry cell weight) β-carotene, which could be used further for constructing cell factories for β-carotene production.

Discuss on model organism and model for geoherbs' study / 中国中药杂志

The scientific essence of geoherbs bases on the attribute of matter. The phenotype of geoherbs from biological point view includes medicinal character, tissue structure, content and composition of the effective components and the therapeutic effect. The forming of geoherb is resulted from the interaction of genotype and environment. It can be expressed by the formula: phenotype = genotype + environmental modification. In order to prove this hypothesis, the authors discussed the model organism and model for geoherbs' study based on Salvia miltiorrhiza.

Cloning and characterization of geranylgeranyl diphosphate synthase gene of Salvia miltiorrhia / 中国中药杂志

<p><b>OBJECTIVE</b>To obtain geranylgeranyl diphosphate synthase gene of Salvia miltiorrhiza, and conduct bioinformatic and transcript expression analysis of the cloned SmGGPS1 gene.</p><p><b>METHOD</b>The degenerate primers were designed based on the conservative regions of GGPS protein sequences from public databases. The target gene was obtained from root of S. miltiorrhiza by use of homologous cDNA amplification and RACE technologies. The sequence alignment was performed using BLAST. The open reading frame was identified by use of the ORF Finder. The protein domains were defined by use of Prosite software and the signal peptide sequence was predicted by Target P1.1. MEGA4.0 was used to conduct multiple amino acid sequence alignment and construct the phylogenetic tree. Roots and leaves at the seedlings stage and roots, stems, leaves, buds and flowers in the flowering stage were sampled for transcript analysis. Semi-quantitative RT-PCR was used to detect the gene expression level. The complete gene of GGPS was obtained from S. miltiorrhiza genomic DNA by PCR using the cDNA-derived specific primer. The gene structure of GGPS was analyzed by comparison of the genomic DNA and its cDNA.</p><p><b>RESULT</b>The obtained 1 298 bp SmGGPS1 cDNA sequence contains an 1095 bp ORF, encoding 364 amino acids. It is predicted that it has a plastid targeting signal peptide of approximately 52 amino acid at the N-terminal end. It is to believe that this is the polyprenyl synthetase signature, and nucleic acid sequence comparison revealed that SmGGPS1 ORF has more than 60% identity to the reported GGPS. RT-PCR semi-quantitative analysis showed that the gene expresses in the all tested tissues, and with much higher level of expression in the leaves in the flowering stage. SmGGPS1 has a 397 bp intron.</p><p><b>CONCLUSION</b>For the first time the cloning of geranylgeranyl diphosphate synthase gene from S. miltiorrhiza was reported, and it provides a good basis for further functional study of SmGGPS1.</p>

Genetic diversity analysis of germplasm resources of Psammosilene tunicoides / 中草药

Objective To analyze the genetic diversity of Psammosilene tunicoides,an endangered and endemic medicinal plant,in southwest China.Methods The genetic diversity of seven representational populations of P.tunicoides including 137 individuals had been investigated by amplified fragment length polymorphisms(AFLP)maker technique.Results The genetic diversity had been revealed as follow:the Nei's genetic diversity index(He),Shannon's information index(I),percentage of polymorphic loci(PPB)were 0.243 4?0.179 1,0.373 5?0.248 5,and 82.30%,respectively at the species level;and 0.091 8?0.161 0,0.140 2?0.236 2,and 30.48%,respectively at population level.The genetic differentiation index(Gst)was 0.624 6 and genetic differentiation coefficient by Shannon's diversity(Ist)was 0.624 6.The result of dendrogram of seven populations indicated that Lijiang and Gejiu of Yunnan populations shared the maximum genetic identity,though they distributed in a relatively great geographical distance;Kunming population of Yunnan had the greater genetic distance from other populations.Nine characteristic fingerprint bands that can distinguish the different populations had been acquired.Conclusion The genetic diversity of P.tunicoides is relatively higher at the species levels,while lower within population levels,and a significant degree of genetic differentiation occurrs among the populations.There is little relativity between the relationship of populations and geographical distance.The combination of characteristic fingerprint bands between intraspecies and populations provide important basis data for germplasm resources diagnostics and plant breeding by AFLP maker technique.