We investigated the percipitation of airborne fungi particles with gravity plates at xidan area of Beijing. Our results show that, 1, The yearly average of the precipitation of airborne fungi particles is 11.0/dish. 5 min; 2,The highest precipitation occurs at 7:00 and 19:00 and the lowest precipitation at 4:00 and 13:00 in one day time; 3, The precipitation is high in the summer and low at the fall; 4, The significant difference of the precipitation between day and night is not observed in this study.

To explore the effects of different organic solvents including trimethylglycine on the PCR amplification of G+C rich DNA templates,two high G+C containing DNA templates (cyclin dependent kinase inhibitor gene ARF and IGFR II) were amplified using standard PCR and modified PCR with the addition of glycerin, dimethylsulfoxide (DMSO), formamide and trimethylglycine respectively. There were no specific amplified products, when standard PCR and modified PCR with the addition of glycerin, DMSO and formamide were used to amplify the G+C rich ARF and IGFR II genes. But the two genes could be specifically amplified with the addition of optimal concentration of trimethylglycine in the PCR mixture. These results indicate that trimethylglycine can abolish or reduce the formation of second structures in G+C rich DNA regions and promote the amplification of high G+C containing DNA templates.

AIM: To study the effect of p19ARF on the biological behavior of human leukemia cells. METHODS: p19ARF was cloned in eukaryotic expression vector pcDNA3.1 and transferred into INK4a/ARF locus-deficient leukemia cells HEL and K562. The changes in biological characteristics of the two p19ARF-transfected cells were observed. RESULTS: The growth of the p19ARF-transfected HEL cells was significantly inhibited compared with the vector-transfected cells; Cell cycle analysis showed that the expression of foreign p19ARF gene resulted in G1 phase cell cycle arrest and apoptosis cell death in some of HEL cells. However, p19ARF had no marked effects on the growth of K562 cells with p53 gene mutation and did not induce apoptosis in K562 cells. CONCLUSION: p19ARF suppressed the growth of leukemia cells by p53 -dependent pathway.