• Applied Biological Chemistry
• /
• v.39 no.5
• /
• pp.403-408
• /
• 1996

Total bacterial community DNA, which was extracted from microcosm soil and field soil after 2,4-D amendments, was analyzed on Southern blots, using the tfdA gene probe derived from plasmid pJP4 and the Spa probe from Sphingomonas paucimobilis. Southern blot analyses with total bacterial DNA extracted from soils Inoculated with Pseudomonas cepacia/pJP4 revealed that DNA probe method could detect the 2,4-D degrading bacteria down to $10^5\;cells/g$ dry soil. In the microcosm experiment, there was a good correlation between 2,4-D degradation and banding patterns in hybridization analyses performed after each 2,4-D treatment using the two probes. When bacterial DNA extracted from microcosm soil was hybridized with the Spa probe, a change in the position of hybrid bands was observed over time in a Southern blot, suggesting that population change or possibly genetic rearrangement in 2,4-D degrading microbial populations occurred in this soil. With the Spa probe, one hybrid DNA band was persistently observed throughout the five 2,4-D additions. When bacterial DNA isolated from the field soil was probed with the tfdA and Spa, strong hybridization signal was observed in the 100 ppm-treated subplot, weak signal In the 10 ppm-treated subplot, and no significant signal in the 1 ppm-treated and control subplots. The data show that DNA probe analyses were capable of detecting and discriminating the indigenous 2,4-D degrading microbial populations in soil amended with 2,4-D under laboratory and field conditions.

• Journal of Bio-Environment Control
• /
• v.16 no.1
• /
• pp.54-61
• /
• 2007

To determine whether antioxidant enzyme systems are related to chilling tolerance, changes of antioxidant enzyme activities during the chilling stress were determined in the leaves of a chilling-tolerant cultivar (Cucurbita ficifolia, cv. Heukjong) and a chilling-sensitive cultivar (Cucurbita moschata, cv. Jaerae 13). Leaves of chilling-tolerant plant have two major isoforms, Fe-SOD and Mn-SOD, at the Rm values of 0.20 and 0.52, respectively. In leaves of chilling-sensitive plant, two major isozymes of SOD was observed, one isoform is Mn-SOD at the Rm value of 0.20, and the other isoform is Cu/zn-SOD at the nm value of 0.58. When plants were treated with chilling stress, Cu/zn-SOD at the Rm value of 0.58 was newly expressed at 10 days after chilling stress in the chilling-tolerant plants, and density of this band increased at five days after chilling stress in the chilling-sensitive plants. One APX isozyme band was observed in unstressed plants of both cultivars. Under the chilling stress one APX isozyme band was newly expressed at 10 days after chilling stress in the chilling-tolerant cultivar. Significant genotype differences were observed fnr POD isozyme banding patterns such as few main isozyme bands in chilling-tolerant plants, and one band in chilling-sensitive plants. Densities of three POD isozyme bands at the Rm of 0.36, 0.40 and 0.54 increased at 10 days after chilling stress in the chilling-tolerant plants, while two bands at the nm of 0.36 and 0.54 increased at 10 days and 20 days after chilling stress in the chilling-sensitive plants, respectively. Activities of SOD, APX and POD significantly increased during five days after chilling stress in both cultivars. In the chilling-tolerant cultivar, activities of these enzymes were higher in chilling-stressed plant than in unstressed plants. However, activities of these enzymes in the chilling-sensitive cultivar decreased rapidly after five days of chilling stress, and were lower in chilling stressed plants than in unstressed plants.