Search Results - (Author, Cooperation:D. Crowley)

2018-04-25

American Physical Society (APS)

0031-9007

1079-7114

Physics

Condensed Matter: Structure, etc.

2018-03-23

American Chemical Society (ACS)

0002-7863

1520-5126

Chemistry and Pharmacology

2011-04-08

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Adenocarcinoma/genetics/physiopathology ; Animals ; Cell Differentiation ; Cell Line, Tumor ; Disease Models, Animal ; Down-Regulation ; *Gene Expression Regulation, Neoplastic ; HMGA2 Protein/genetics ; Humans ; Lung Neoplasms/genetics/physiopathology ; Mice ; Nuclear Proteins/*genetics/*metabolism ; Transcription Factors/*genetics/*metabolism

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

To eliminate the confounding effects of microorganisms and to examine the direct utilization of microbial siderophores as iron sources by higher plants, a hydroponic cultural system and methodology was developed to grow plants with axenic roots. This report presents a description of this system, and also its use to determine the efficacy of the microbial siderophore ferrioxamine B (FOB), compared to the synthetic iron chelate FeEDTA, and the phytosiderophores (PS) of barley as an iron source for alleviating iron stress in the model dicot cucumber. It was observed that FOB gave superior plant biomass and was preferentially utilized to restore chlorophyll synthesis in long-term experiments when chelates were supplied at 5mmol m−3 concentrations and nutrient solution was buffered against pH change at 7.4 with solid phase CaCO3. In addition, autoradiograms indicated that 59Fe from FOB was rapidly translocated to shoots through vascular tissues and was specifically distributed to regions of rapid growth and to iron-stressed, but still expanding young leaves. The siderophore itself could be detected within 2h in xylem exudates, regardless of whether or not plants were exposed to metabolic inhibitors. It was concluded that the FOB and iron were taken up by the axenic roots of cucumber in a highly efficient manner, most likely as the iron-siderophore complex, and at rates that could be significant to dicot nutrition. The results also suggested that cucumber may transport FOB through the transpiration stream to upper parts of plants, where the iron would be reductively released from the siderophore for shoot nutrition.

Electronic Resource

0036-9241

History

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Abstract Partial bioremediation of polychlorinated biphenyl (PCB)-contaminated soil was achieved by repeated applications of PCB-degrading bacteria and a surfactant applied 34 times over an 18-week period. Two bacterial species, Arthrobacter sp. strain B1B and Ralstonia eutrophus H850, were induced for PCB degradation by carvone and salicylic acid, respectively, and were complementary for the removal of different PCB congeners. A variety of application strategies was examined utilizing a surfactant, sorbitan trioleate, which served both as a carbon substrate for the inoculum and as a detergent for the mobilization of PCBs. In soil containing 100 μg Aroclor 1242 g−1 soil, bioaugmentation resulted in 55–59% PCB removal after 34 applications. However, most PCB removal occurred within the first 9 weeks. In contrast, repeated addition of surfactant and carvone to non-inoculated soil resulted in 30–36% PCB removal by the indigenous soil bacteria. The results suggest that bioaugmentation with surfactant-grown, carvone-induced, PCB-degrading bacteria may provide an effective treatment for partial decontamination of PCB-contaminated soils.

Electronic Resource

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Abstract Carvone, the principal component of spearmint oil, induces biodegradation of polychlorinated biphenyls (PCB) by Arthrobacter sp. strain B1B. This study investigated the effectiveness of the repeated application of carvone-induced bacteria for bioremediation of Aroclor-1242-contaminated soil. Control treatments compared a single inoculation of carvone-induced cells, repeated applications of noninduced cells, and repeated applications of cell-free carvone/fructose medium. The results showed that repeated application of carvone-induced bacteria was the most effective treatment for mineralizing PCB, resulting in 27 ± 6% degradation of Aroclor 1242 after 9 weeks; whereas a single application of cells resulted in no significant degradation. Addition of cell-free, carvone/fructose medium resulted in 10% degradation of PCB, which suggests that this treatment stimulated biodegradation of PCB by the indigenous microflora. The di- and trichlorobiphenyls were the most readily degraded congeners. More highly chlorinated congeners, which had been previously shown to be degraded in liquid culture, were not substantially degraded in soil, indicating that low bioavailability may have limited their degradation. With the development of new technology, which permits automated in situ fermentation and delivery of degrader microorganisms, the repeated application of carvone-induced bacteria may facilitate bioremediation of PCB-contaminated soils.

Electronic Resource

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Abstract Bioaugmentation has previously been unreliable for the in situ clean-up of contaminated soils because of problems with poor survival and the rapid decline in activity of the bacterial inoculum. In an attempt to solve these problems, a 500-l batch fermenter was investigated for its ability to deliver inoculum repeatedly to contaminated soils via irrigation lines. In a field experiment, mesocosms were filled with 350 kg soil containing 100 mg kg−1 atrazine, and inoculated one, four or eight times with an atrazine-degrading bacterial consortium that was produced in the fermenter. After 12 weeks, no significant degradation of atrazine had occurred in soil that was inoculated only once; whereas, mesocosms inoculated four and eight times mineralized 38% and 72% of the atrazine respectively. Similar results were obtained in a laboratory experiment using soil contaminated with 100 mg kg−1 [14C]atrazine. After 35 days, soil that was inoculated once with 108 cfu ml−1 of the consortium or with the atrazine-degrading bacterium, Pseudomonas sp. strain ADP, mineralized 17% and 35% of the atrazine respectively. In comparison, microcosms inoculated every 3 days with the consortium or with Pseudomonas sp. (ADP) mineralized 64% or 90% of the atrazine over this same period. Results of these experiments suggest that repeated inoculation from an automated fermenter may provide a strategy for bioaugmentation of contaminated soil with xenobiotic-degrading bacteria.

Electronic Resource

1573-5036

chelate ; ecology ; membrane transport ; plant iron nutrition ; plant-microbial interactions ; rhizosphere

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Most bacteria, fungi, and some plants respond to Fe stress by the induction of high-affinity Fe transport systems that utilize biosyrthetic chelates called siderophores. To competitively acquire Fe, some microbes have transport systems that enable them to use other siderophore types in addition to their own. Bacteria such as Escherichia coli achieve this ability by using a combination of separate siderophore receptors and transporters, whereas other microbial species, such as Streptomyces pilosus, use a low specificity, high-affinity transport system that recognizes more than one siderophore type. By either strategy, such versatility may provide an advantage under Fe-limiting conditions; allowing use of siderophores produced at another organism's expense, or Fe acquisition from siderophores that could otherwise sequester Fe in an unavailable form. Plants that use microbial siderophores may also be more Fe efficient by virtue of their ability to use a variety of Fe sources under different soil conditions. Results of our research examining Fe transport by oat indicate parity in plant and microbial requirements for Fe and suggest that siderophores produced by root-colonizing microbes may provide Fe to plants that can use the predominant siderophore types. In conjunction with transport mechanisms, ecological and soil chemical factors can influence the efficacy of siderophores and phytosiderophores. A model presented here attempts to incorporate these factors to predict conditions that may govern competition for Fe in the plant rhizosphere. Possibly such competition has been a factor in the evolution of broad transport capabilities for different siderophores by microorganisms and plants.

Electronic Resource

0098-1273

Physics ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

We report flow birefringence observations of polyethylene oxide solutions in a four roll mill where the flow field in the central region of the mill approximates well to that of pure shearing flow. When flow birefringence is observed it is seen to be highly localized within a region close to the “outgoing” asymptotic plane of flow. The phenomenon can be explained in terms of the flow birefringence corresponding to high extension of some polymer chains where the localization is caused by the chains requiring sufficient time in the flow field to become extended. This explanation has important consequences in all “persistently extensional flows” and can explain the origin of previously published results of localized flow birefringence observed for polyethylene solutions in axial compression and axial extensional flows.

8 Ill.

Electronic Resource