The operon for cytokinin biosynthesis of Erwinia herbicola pv. gypsophilae contains two promoters and is plant induced

2001 ◽  
Vol 47 (12) ◽  
pp. 1126-1131 ◽  
Author(s):  
Ming Guo ◽  
Shulamit Manulis ◽  
Isaac Barash ◽  
Amnon Lichter
Keyword(s):  
Transcriptional Activity ◽  
Ice Nucleation ◽  
Luria Bertani ◽  
Northern Hybridization ◽  
Cytokinin Biosynthesis ◽  
Erwinia Herbicola ◽  
Indigenous Plasmid ◽  
Luria Bertani Broth ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

The operon for cytokinin biosynthesis in the gall-forming bacterium Erwinia herbicola pv. gypsophilae (Ehg) has been previously shown to reside on an indigenous plasmid (pPATHEhg) that is mandatory for pathogenicity. This operon consists of two genes: the first open reading frame (pre-etz) is of unknown function, whereas the second one (etz) encodes for isopentenyl transferase. Northern hybridization performed with the wild-type strain Ehg824-1 grown in Luria-Bertani broth demonstrated two transcripts of which an etz-specific transcript (1.0 kb) was predominant. Fusion of upstream DNA fragments of both pre-etz and etz to the ice nucleation reporter gene inaZ in pVSP61 showed high ice nucleation activity in both cultures, confirming the presence of two independent promoters. An increase of 1–1.5 orders in transcriptional activity of these promoters was observed following inoculation of gypsophila cuttings. Mutants of Ehg824-1 were generated by insertion of inaZ into pre-etz and etz using the transposon reporter Tn3-Spice. An increase of about two orders in transcriptional activity was recorded with both mutants following inoculation of gypsophila or bean cuttings. A similar induction was also observed when the bacteria were applied to the leaf surface of these plants. Unlike other virulence genes present on the pPATHEhg, neither pre-etz nor etz was regulated by the adjacent hrp gene cluster.Key words: pre-etz and etz operon, cytokinin, plant induction, ice nucleation activity.

scholarly journals Seasonal ice nucleation activity of water samples from alpine rivers and lakes in Obergurgl, Austria

2021 ◽  
pp. 149442
Author(s):  
Philipp Baloh ◽  
Regina Hanlon ◽  
Christopher Anderson ◽  
Eoin Dolan ◽  
Gernot Pacholik ◽  
...  
Keyword(s):  
Water Samples ◽  
Ice Nucleation ◽  
Rivers And Lakes ◽  
Nucleation Activity ◽  
Alpine Rivers ◽  
Ice Nucleation Activity

Ice nucleation activity of iron oxides via immersion freezing and an examination of the high ice nucleation activity of FeO

2021 ◽  
Vol 23 (5) ◽  
pp. 3565-3573
Author(s):  
Esther Chong ◽  
Katherine E. Marak ◽  
Yang Li ◽  
Miriam Arak Freedman
Keyword(s):  
Iron Oxides ◽  
Functional Groups ◽  
Ice Nucleation ◽  
Mechanical Processing ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

FeO has enhanced ice nucleation activity due to functional groups that are exposed upon mechanical processing.

scholarly journals Effects of atmospheric conditions on ice nucleation activity of <i>Pseudomonas</i>

2012 ◽  
Vol 12 (22) ◽  
pp. 10667-10677 ◽  
Author(s):  
E. Attard ◽  
H. Yang ◽  
A.-M. Delort ◽  
P. Amato ◽  
U. Pöschl ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Acidic Ph ◽  
Bacterial Cells ◽  
Atmospheric Conditions ◽  
Ice Nucleation Protein ◽  
Ice Melt ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

scholarly journals Ice nucleation activity identified in some phytopathogenic Fusarium species

2005 ◽  
Vol 77 (2) ◽  
pp. 83-92 ◽  
Author(s):  
C. Richard ◽  
J.-G. Martin ◽  
S. Pouleur
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Species ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Free Living ◽  
Factors Affecting ◽  
Pure Cultures ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Positive Controls

In order to know which species of Fusarium are ice nucleating and to determine the factors affecting their pathogenicity, ice nucleation activity (INA) was examined in Fusarium oxysporum, F. sporotrichioides, and F. tricinctum. Positive controls (lna+) used were F. acuminatum and F. avenaceum. The test for fungal INA was done with a simple and rapid tube nucleation assay. Twelve out of the 42 F. oxysporum isolates, and 8 out of 14 F. tricinctum isolates were lna+. No INA was detected in F sporotrichioides. In this test the threshold freezing temperature tended to increase with culture age, reaching a peak of -1°C in a few samples, which is as high as the warmest INA reported for bacteria, and higher than the INA detected in pure cultures of free-living fungi, lichen fungi, lichen algae and cyanobacteria. This is the first report of INA for F oxysporum.

scholarly journals High-Flow-Rate Impinger for the Study of Concentration, Viability, Metabolic Activity, and Ice-Nucleation Activity of Airborne Bacteria

2017 ◽  
Vol 51 (19) ◽  
pp. 11224-11234 ◽  
Author(s):  
Tina Šantl-Temkiv ◽  
Pierre Amato ◽  
Ulrich Gosewinkel ◽  
Runar Thyrhaug ◽  
Anaïs Charton ◽  
...  
Keyword(s):  
Flow Rate ◽  
Metabolic Activity ◽  
Ice Nucleation ◽  
High Flow ◽  
High Flow Rate ◽  
Airborne Bacteria ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Ice nucleation activity of bacteria isolated from snow compared with organic and inorganic substrates

2008 ◽  
Vol 5 (6) ◽  
pp. 373 ◽  
Author(s):  
Roya Mortazavi ◽  
Christopher T. Hayes ◽  
Parisa A. Ariya
Keyword(s):  
Bacterial Species ◽  
Ice Nucleation ◽  
Detailed Knowledge ◽  
Bacterial Populations ◽  
Inorganic Aerosols ◽  
Ice Nucleators ◽  
Species Population ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Snow Samples

Environmental context. Biological ice nucleators have been found to freeze water at very warm temperatures. The potential of bio-aerosols to greatly influence cloud chemistry and microphysics is becoming increasingly apparent, yet detailed knowledge of their actual role in atmospheric processes is lacking. The formation of ice in the atmosphere has significant local, regional and global influence, ranging from precipitation to cloud nucleation and thus climate. Ice nucleation tests on bacteria isolated from snow and laboratory-grown bacteria, in comparison with those of known organic and inorganic aerosols, shed light on this issue. Abstract. Ice nucleation experiments on bacteria isolated from snow as well as grown in the laboratory, in comparison with those of known organic and inorganic aerosols, examined the importance of bio-aerosols on cloud processes. Snow samples were collected from urban and suburban sites in the greater Montreal region in Canada (45°28′N, 73°45′W). Among many snow bacterial isolates, eight types of bacterial species, none belonging to known effective ice nucleators such as Pseudomonas or Erwinia genera, were identified to show an intermediate range of ice nucleation activity (–12.9 ± 1.3°C to –17.5 ± 2.8°C). Comparable results were also obtained for molten snow samples and inorganic suspensions (kaolin and montmorillonite) of buffered water solutions. The presence of organic molecules (oxalic, malonic and succinic acids) had minimal effect (<2°C) on ice nucleation. Considering experimental limitations, and drawing from observation in snow samples of a variety of bacterial populations with variable ice-nucleation ability, a shift in airborne-species population may significantly alter glaciation processes in clouds.

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