Non-target-site resistance to ALS-inhibiting herbicides in a Sagittaria trifolia L. population.

Sagittaria trifolia L. is one of the most competitive weeds in rice fields in northeastern China. The continuous use of acetolactate synthase (ALS)-inhibitors has led to the evolution of herbicide resistant S. trifolia. A subpopulation BC1, which was derived from the L1 population, was analyzed using DNA sequencing and ALS enzyme activity assays and levels of resistance to five ALS-inhibiting herbicides was determined. DNA sequencing and ALS enzyme assays revealed no amino acid substitutions and no significant differences in enzyme sensitivity between susceptible and resistant populations. Whole-plant dose-response experiments showed that the BC1 population exhibited different levels of resistance (resistance ratios ranging from 2.14 to 51.53) to five ALS herbicides, and the addition of malathion (P450 inhibitor) to bensulfuron-methyl, penoxsulam and bispyribac-sodium strongly reduced the dry weight accumulation of the BC1 population compared with the effects of the three herbicides alone. The results of the present study demonstrated that the BC1 population has evolved non-target-site resistance to ALS-inhibiting herbicides.

Target-site resistance to bensulfuron-methyl in Sagittaria trifolia L. populations.

Sagittaria trifolia L. is one of the most serious weeds in paddy fields in northeast of China and cannot be controlled effectively by bensulfuron-methyl in recent years. In this study, two suspected resistant S. trifolia populations (R1 and R2) were collected in Liaoning province of China. Whole-plant dose-response studies showed that R1 and R2 were highly resistant to bensulfuron-methyl, with the GR50 R/S ratios of 76.99 and 49.94 respectively. In vitro acetolactate synthase (ALS) assays revealed that resistance was due to reduced sensitivity of the ALS to bensulfuron-methyl inhibition, with I50 R/S ratios of 81.86 and 67.48 for R1 and R2, respectively. Total ALS activity was similar for the S and R2 populations, whereas the R1 population displayed significantly higher ALS activity than did the S population. The mutations Pro-197-Leu and Pro-197-Ser were identified in the ALS gene of the R1 and R2 populations, respectively. This is the first report examining bensulfuron-resistant S. trifolia in Liaoning province, China. The Pro197 mutation is likely responsible for resistance to bensulfuron-methyl in S. trifolia populations.

[Studies on the properties and co-immobilization of manganese peroxidase].

White-rot fungus manganese peroxidase (MnP) oxidizes a wide range of substrates, rendering it an interesting enzyme for potential applications. The stability of MnP can be improved by immobilization. With sodium alginate, gelatin, or chitosan as a carrier, and glutaraldehyde as the crosslinking agent, MnP was co-immobilized using the embed-crosslinked method and the adsorb-crosslinked method. The immobilization conditions and the partial properties of the three immobilized enzymes were investigated. When compared with the free enzyme, the optimum pH values and the temperatures of the three immobilized MnPs carried by alginate, gelatin, and chitosan were respectively shifted from 7.0 to 5.0, 5.0, 3.0 and from 35 degrees C to 75 degrees C , 55 degrees , 75 degrees C . The thermostabilities of the three immobilized MnPs were considerably better than that of the native enzyme. The chitosan-decreased by less than 5% even after repeated use for 6 - 9 times. The ability of decolorizing azo dyes in static and shaky situation by gelatin-immobilized MnP approached to the free enzyme, and there was no loss of enzyme activity during 2 repeated batch reactions.

[Screening differentially expressed genes in the process of vascular smooth muscle cell calcification in vitro].

AIM: The process of vascular calcification involves various genetic alterations which may play a very important role in the vascular calcification. Vascular smooth muscle cells undoubtedly composed the main part of vascular cells, and are involved in vascular calcification. So bovine artery smooth muscle cell (BASMC) was used to investigate the gene changes during BASMC's calcification. METHODS: Bovine artery smooth muscle cells cultured in vitro was induced calcified by beta-Glycerophosphate (beta-GP). Using DD-PCR technique to screening differentially expressed genes and those differentially expressed bands were reexamined by reverse Northern blot. All the ESTs were sequenced and BLAST with GenBank. RESULTS: Total 65 cDNAs were isolated as differentially expressed genes and 40 of them were successfully reamplified. Using reverse-Northern blot, seven of these 40 cDNAs were reproducibly expressed differentially between the two cells. Three of them are new bands and have not been reported before. CONCLUSION: This is the first time using DD-PCR to screen differentially expressed genes of BASMC calcification. Seven related ESTs were identified relating to BASMC calcification.