Molecular cloning of squalene synthase gene form Paris polyphylla and its expression in Escherichia coli / 中国中药杂志

<p><b>OBJECTIVE</b>To clone the cDNA sequence of squalene synthase gene from Paris polyphylla, and characterize the biological features of the obtained SQS.</p><p><b>METHOD</b>Using homology cloning and RACE technique, a full-length cDNA sequence of PpSQS gene was isolated from P. polyphylla. The obtained sequence was analyzed by bioinformatics softwares. A plasmid [named pET-30b (+)-PpSQS] was constructed for prokaryotic expression the recombinant PpSQS.</p><p><b>RESULT</b>The full-length cDNA of PpSQS gene is 1 498 bp, which contains a 1 212 bp ORF. Sequence analysis indicated that PpSQS encoded 403 amino acids residues with a calculated molecular weight (MW) of 46.36 kDa and an isoelectric point (pI) of 6.83. SDS-PAGE results showed that the recombinant PpSQS was expressed in Escherichia coli BL21 (DE3) by inducing with 1 mmol x L(-1) IPTG.</p><p><b>CONCLUSION</b>The full-length cDNA sequence of PpSQS gene was obtained from P. polyphylla, and its molecular features were consisted with classic SQS in plant. The recombinant PpSQS was successfully expressed in E. coli.</p>

Studies on chromosome numbers of Salvia miltiorrhiza, S. flava and S. evansiana / 中国中药杂志

<p><b>OBJECTIVE</b>To study the numbers of chromosome in Chinese herb Salvia miltiorrhiza from 7 provinces in China, and S. flava as well as S. evansiana from Yunnan province in China.</p><p><b>METHOD</b>The young root was treated with the mixture of ice and water for 24 h, fixed with Carony's fixative for 6-12 h. After differentiating for 10-12 min with 1 mol x L(-1) hydrochloric acid at 60 'C and staining with carbol fuchsin,the section was observed under microscope.</p><p><b>RESULT</b>Chromosome numbers of S. miltiorrhiza and S.flava were 2n = 2x = 16. The numbers of S. evansiana were 2n = 4x = 32. The basic numbers of the chromosomes were x = 8. And tetraploids were observed in S. miltiorrhiza from Sichuan provices and Shandong provices.</p><p><b>CONCLUSION</b>The basic number of the chromosomes are x = 8. The chromosome numbers of S. miltiorrhiza, S.flava and S. evansiana are 16,16 and 32 respectively. As the chromosomes are the small or micro-small ones, it is difficult to use them for karyotype.</p>