Background: The major risk factor for the development of COPD is cigarette smoking. Smoking causes activation of resident cells and the recruitment of inflammatory cells into the lungs, which leads to release of pro-inflammatory cytokines, chemotactic factors, oxygen radicals and proteases. In the present study evidence is found for a new cellular mechanism that refers to a link between smoking and inflammation in lungs.
In grazing systems dung is an important source of nutrients which can increase soil fertility and contribute to nutrient cycling through increased pasture production. Changes in soil chemical and biological properties and pasture production were measured below and around dung pads created in the field. Almost 65% of the total dung P remained after 45 days and about two-thirds of the pad fresh weight had disappeared in that time, indicating that physical degradation is the mechanism of incorporation of dung P. All the pads bar one were completely degraded by 112 days. At this time, soil pH and EC increased under dung pads as did Olsen extractable inorganic phosphorus (Pi) and total phosphorus (Pt), with these changes observed at 0-5 and 5-10 cm depths. Bicarbonate extractable soil organic phosphorus (Po) was not affected by dung and the observed differences in soil Po:Pi ratios were largely influenced by the substantial addition of inorganic P from dung. Dung increased the P buffering capacity of the 0-5 cm soil samples collected at the end of the experiment, potentially contributing to the increased extractable soil P measured under the pads. Dung also changed soil properties in 0-10 cm samples with increases in soil pH, EC, Colwell P and Colwell K recorded even long after the dung had completely disappeared. Microbial biomass carbon increased under dung pads in the 0-10 cm soil samples in the first 45 days after pads were applied. Total herbage production and ryegrass biomass increased significantly under and around the pads by 112 days after dung was applied. The botanical composition changed significantly with increased ryegrass contents observed, but only under the dung pads. This experiment demonstrated that increases in pasture around dung pads in the field are not solely due to animal rejection.
This study was conducted to investigate the role of 1-aminocyclopropane-1-carboxylate (ACC) deaminase in Pseudomonas fluorescens strain REN 1 and its ability to reduce ethylene levels produced during stress, endophytically colonize and promote the elongation of the roots of rice seedlings under gnotobiotic conditions. We isolated 80 bacteria from inside roots of rice plants grown in the farmers' fields in Guilan, Iran. All of the isolates were characterized for plant growth promoting (PGP) traits. In addition, the colonization assay of these isolates on rice seedlings was carried out to screen for competent endophytes. The best bacterial isolate, based on ACC deaminase production, was identified and used for further study. 16S rDNA sequence analysis revealed that the endophyte was closely related to Pseudomonas fluorescens. The results of this study showed ACC deaminase containing P. fluorescens REN1 increased in vitro root elongation and endophytically colonized the root of rice seedlings significantly, as compared to control under constant flooded conditions. The trait of low amount of indole-3-acetic acid (IAA) production (<15 μg mL −1 ) and the high production of ACC deaminase by bacteria may be main factors in colonizing rice seedling roots compared to other PGP traits (siderophore production and phosphate solubilization) in this study. Endophytic IAA and ACC deaminase-producing bacteria may be preferential selections by rice seedlings. Therefore, it may be suggested that the utilization of ACC as a nutrient gives the isolates advantages in more endophytic colonization and increase of root length of rice seedlings.
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