Using green fluorescent protein as a reporter to monitor elimination of selectable marker genes from transgenic plants / 生物工程学报

In genetic modification of plants, once the transformants are obtained, selection markers are no longer required in mature plants. At present, the Cre/lox site-specific recombination system is most widely used to eliminate the selectable marker genes from the transgenic plants. In this study, attempt was made to favour the selection of marker-free plants in the re-transformation method. Green fluorescent protein (GFP) can be directly visualized in living cells, tissues or organisms under UV illumination. This advantage of GFP is exploited in the development of a practical approach in which GFP is used as a visual marker to monitor the removal of the selectable marker gene from transgenic plants. For that purpose, the pGNG binary vector was constructed, in which the GFP gene (gfp) was linked to the expression cassette Nos P-nptII-NosT and the two units were cloned between two directly-orientated lox sites. The CaMV 35S promoter was placed before the first lox site and used to drive GFP expression. The beta-glucuronidase gene (gus) of Escherichia coli was cloned behind the second lox site without a promoter, thus would not be expressed in this position. Tobacco plants were first transformed with pGNG and selected on kanamycin (Kan)-containing media. Regenerated transgenic shoots were readily singled out by GFP fluorescence. The GFP-expressing plants were then re-transformed with pCambia1300-Cre containing hygromycin phosphotransferase gene (hpt) as a selectable marker gene. The Cre-mediated recombination resulted in the elimination of lox-flanked genes, herein gfp and nptII, from the plant genome and brought the GUS gene next to the 35S promoter. Our data demonstrated that transgenic plants free of nptII were easily selected by monitoring the loss of green fluorescence, and at the same time, GUS (here as a target protein) was expressed in the nptII-free plants. Finally, hpt and cre were removed from the progenies of the nptII-free plants by gene segregation.

The effect of changing body posture on thrombin activity and concentration / 中国应用生理学杂志

<p><b>AIM</b>To provide proof for Evidence-based Medicine as well quality control, our laboratory detected the thrombin activity on various body position.</p><p><b>METHODS</b>By autogenous contrast and cross matched survey, 105 volunteers divided into 3 season patches of winter, spring and summer, blood samples were drawn from the same part in both standing and lying position. Both samples and the quality control were detected to investigate the effect of the body position to thrombin activity's changing. The data were analyzed by SPSS 10.0.</p><p><b>RESULTS</b>Taking the lying's data as baseline, the average changing on all those the "5" index was 7.07% and the highest changing reached 9.33%. This kind changing had great significant differences (P < 0.01). According to the t value, sequences ranged: FIB > TT > PT > INR > APTT. FIB, TT and APTT's values slowly raised, adversely PT and INR slowly went down. While sitting for 15 min after lying, these indices returned to 95.2% of the original value in sitting position in addition. Season, age and device had no relationship with body position.</p><p><b>CONCLUSION</b>Changing body position can result in obvious physiological variation of thrombin activity.</p>