scholarly journals A Technique to Measure Ice Nuclei in the Contact Mode

2014 ◽  
Vol 31 (4) ◽  
pp. 913-922 ◽  
Author(s):  
Joseph Niehaus ◽  
Kristopher W. Bunker ◽  
Swarup China ◽  
Alexander Kostinski ◽  
Claudio Mazzoleni ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Contact Mode ◽  
Droplet Collision ◽  
Ice Nuclei ◽  
Air Water Interface ◽  
Temperature Controlled ◽  
The Difference ◽  
A New Technique ◽  
Number Of Particles

Abstract This study presents a new technique to study ice nucleation by aerosols in the contact mode. Contact freezing depends upon the interaction of a supercooled droplet of water and an aerosol particle, with the caveat that the particle must be at the air–water interface. To measure nucleation catalyzed in this mode, the technique employs water droplets that are supercooled via a temperature-controlled copper stage, then pulls aerosol-laden air past them. Particles deposit out of the airstream and come into contact with the surface of the droplet. The probability that a particle–droplet collision initiates a freezing event, necessitating knowledge of the total number of particles that collide with the droplet, is reported. In tests of the technique, ice nucleation by the bacteria Pseudomonas syringae is found to be more efficient in the contact mode than in the immersion mode by two orders of magnitude at −3°C with the difference diminishing by −8°C.

scholarly journals Release of cell-free ice nuclei from Halomonas elongata expressing the ice nucleation gene inaZ of Pseudomonas syringae

2000 ◽  
Vol 89 (5) ◽  
pp. 785-792 ◽  
Author(s):  
G. Tegos ◽  
C. Vargas ◽  
A. Perysinakis ◽  
A.I. Koukkou ◽  
A. Christogianni ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Ice Nuclei ◽  
Halomonas Elongata

THE EFFECT OF HIGH TEMPERATURE STORAGE ON THE CAPACITY OF AN ICE-NUCLEATING-ACTIVE BACTERIUM AND FUNGUS TO REDUCE INSECT COLD-TOLERANCE

1995 ◽  
Vol 127 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Paul Fields ◽  
Stéphan Pouleur ◽  
Claude Richard
Keyword(s):  
Cold Tolerance ◽  
Pseudomonas Syringae ◽  
Cold Hardiness ◽  
Insect Pest ◽  
Cold Treatment ◽  
Stored Grain ◽  
Supercooling Point ◽  
Ice Nuclei ◽  
The Difference ◽  
Cold Hardy

AbstractCold treatment is used to control the rusty grain beetle (Cryptolestes ferrugineus) (Coleoptera: Cucujidae), the predominant insect pest of stored grain in Canada. However, because it is difficult to cool the grain enough to control C. ferrugineus quickly, we have examined ways to reduce the cold-tolerance of adult C. ferrugineus, the most cold-hardy stage. We compared the efficacy of two ice nucleators, Pseudomonas syringae and Fusarium avenaceum, to decrease cold-tolerance of this insect, as well as their thermal stability. Ice nuclei from the bacteria P. syringae raised C. ferrugineus supercooling point from −17 to −6 °C, and increased mortality at −9°C for 24 h from 11 to 100%. Pseudomonas syringae held at 30°C for 16 weeks showed only a slight decline in its ability to reduce C. ferrugineus cold-tolerance. The fungus F. avenaceum raised the supercooling point of C. ferrugineus from −17 to −9°C, but only increased the mortality at −9°C for 24 h from 10 to 33%. Wheat treated with F. avenaceum and held at 30°C for 4 weeks reduced the cold-hardiness of C. ferrugineus, but had no effect after 8 weeks at 30°C. One reason for the difference between the two nucleators is that P. syringae had approximately 1000 times more ice nuclei per gram than did F. avenaceum. These results suggest that P. syringae is stable enough to reduce C. ferrugineus cold-tolerance after several weeks on warm grain. We discuss possible ways to increase the ice-nucleating activity of F. avenaceum.

scholarly journals Urediospores of <i>Puccinia</i> spp. and other rusts are warm-temperature ice nucleators and harbor ice nucleation active bacteria

2012 ◽  
Vol 12 (10) ◽  
pp. 26143-26171 ◽  
Author(s):  
C. E. Morris ◽  
D. C. Sands ◽  
C. Glaux ◽  
J. Samsatly ◽  
S. Asaad ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Plant Diseases ◽  
Spatial And Temporal Variability ◽  
Warm Temperature ◽  
Ice Nuclei ◽  
Ice Nucleators ◽  
The Usa ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. In light of various features of the biology of the rust fungi and of the epidemiology of the plant diseases they cause that illustrate the important role of rainfall in their life history, we have characterized the ice nucleation activity (INA) of the aerially disseminated spores (urediospores) of this group of fungi. Urediospores of this obligate plant parasite were collected from natural infections from 7 species of weeds in France, from coffee in Brazil and from field and greenhouse-grown wheat in France, the USA, Turkey and Syria. Immersion freezing was used to determine freezing onset temperatures and the abundance of ice nuclei in suspensions of washed spores. Microbiological analyses of spores and subsequent tests of the ice nucleation activity of the bacteria associated with spores were deployed to quantify the contribution of bacteria to the ice nucleation activity of the spores. All samples of spores were ice nucleation active having freezing onset temperatures as warm as −4 °C. Spores in most of the samples carried cells of ice nucleation-active strains of the bacterium Pseudomonas syringae (at rates of less than 1 bacterial cell per 100 urediospores), but bacterial INA accounted for only a small fraction of the INA observed in spore suspensions. Changes in the INA of spore suspensions after treatment with lysozyme suggest that the INA of urediospores involves a polysaccharide. Based on data from the literature, we have estimated the concentrations of urediospores in air at cloud height and in rainfall. These quantities are very similar to those reported for other biological ice nucleators in these same substrates. We suggest that air sampling techniques have ignored the spatial and temporal variability of atmospheric concentrations that occur under conditions propitious for precipitation that could increase their local abundance intermittently. Nevertheless, we propose that the relative low abundance of warm-temperature biological ice nucleators in the atmosphere corresponds to optimal conditions for the processes of evolution to positively select for INA.

scholarly journals Measurements of ice nucleation by mineral dusts in the contact mode

2012 ◽  
Vol 12 (8) ◽  
pp. 20291-20309 ◽  
Author(s):  
K. W. Bunker ◽  
S. China ◽  
C. Mazzoleni ◽  
A. Kostinski ◽  
W. Cantrell
Keyword(s):  
High Temperatures ◽  
Laboratory Experiments ◽  
Ice Nucleation ◽  
Submicron Particles ◽  
Cloud Physics ◽  
Contact Mode ◽  
Earth’S Atmosphere ◽  
Ice Nuclei ◽  
Mineral Dusts ◽  
Earth's Atmosphere

Abstract. Formation of ice in Earth's atmosphere at temperatures above approximately −20 °C is one of the outstanding problems in cloud physics. Contact nucleation has been suggested as a possible mechanism for freezing at relatively high temperatures; some laboratory experiments have shown contact freezing activity at temperatures as high as −4 °C. We have investigated Arizona Test Dust and kaolinite as contact nuclei as a function of size and temperature and find that the fraction of submicron particles that are active as contact ice nuclei is less than 10−3 for −18 °C and greater. We also find that the different dusts are quite distinct in their effectiveness as contact nuclei; Arizona Test Dust catalyzed freezing in the contact mode at all mobility diameters we tested at −18 °C whereas kaolinite triggered freezing only for mobility diameters of 1000 and 500 nm at that temperature.

scholarly journals Phenotypic and Genetic Analysis of Epiphytic Pseudomonas syringae Populations from Sweet Cherry in Michigan

Plant Disease ◽  
2008 ◽  
Vol 92 (3) ◽  
pp. 372-378 ◽  
Author(s):  
Lisa J. Renick ◽  
Andrea G. Cogal ◽  
George W. Sundin
Keyword(s):  
Pseudomonas Syringae ◽  
Sweet Cherry ◽  
Ice Nucleation ◽  
Copper Resistance ◽  
Ice Nuclei ◽  
Polymerase Chain ◽  
Clear Differentiation ◽  
Reduced Rate ◽  
Arbitrarily Primed Pcr ◽  
High Level

A severe outbreak of bacterial canker occurred on sweet cherry in Michigan in 2002. Blossom infection and subsequent canker formation was observed following a prolonged freeze event during bloom. Epiphytic blossom isolates of Pseudomonas syringae were recovered from 39 orchards from the three major cherry-growing areas (southwest [SW], west-central [WC], and northwest [NW]) of Michigan in 2003 and 2004. Average P. syringae populations over 2 years were 4.0, 5.1, and 4.8 log10 CFU/g of blossom tissue from the SW, WC, and NW areas, respectively. In 2003, copper-resistant P. syringae comprised 47.4, 21.1, and 3.1% of the total populations from the SW, WC, and NW areas, respectively, and levels of copper resistance were similar in 2004. Identification of 10 randomly chosen isolates from each orchard using polymerase chain reaction (PCR) assays indicated that 75 and 52% of the isolates from 2003 and 2004, respectively were P. syringae pv. syringae and that 1% and 23% of the isolates from 2003 and 2004, respectively, were P. syringae pv. morsprunorum. In addition, we were unable to determine the pathovar status of approximately 25% of the isolates each year, suggesting that a third P. syringae pathovar also was present in Michigan sweet cherry orchards. Pathogenicity on immature cherry fruit was confirmed for all P. syringae isolates. The frequency of ice nucleation was assessed for 44 individual P. syringae pv. syringae isolates, and the mean number of cells per active ice nucleus was 1,883. Extrapolating from this result, we estimated that active ice nuclei are present on most sweet cherry blossoms in Michigan orchards. Genetic fingerprinting of P. syringae pv. syringae using arbitrarily primed PCR indicated a high level of diversity and a clear differentiation of these organisms from the P. syringae isolates of unknown pathovar. A 2-year field trial evaluating the effect of dormant copper applications in spring and reduced-rate copper applications prior to bloom showed that these treatments were inconsistent in reducing P. syringae populations on blossoms.

scholarly journals Urediospores of rust fungi are ice nucleation active at > −10 °C and harbor ice nucleation active bacteria

2013 ◽  
Vol 13 (8) ◽  
pp. 4223-4233 ◽  
Author(s):  
C. E. Morris ◽  
D. C. Sands ◽  
C. Glaux ◽  
J. Samsatly ◽  
S. Asaad ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Rust Fungi ◽  
Plant Diseases ◽  
Ice Nuclei ◽  
Ice Nucleators ◽  
The Usa ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Various features of the biology of the rust fungi and of the epidemiology of the plant diseases they cause illustrate the important role of rainfall in their life history. Based on this insight we have characterized the ice nucleation activity (INA) of the aerially disseminated spores (urediospores) of this group of fungi. Urediospores of this obligate plant parasite were collected from natural infections of 7 species of weeds in France, from coffee in Brazil and from field and greenhouse-grown wheat in France, the USA, Turkey and Syria. Immersion freezing was used to determine freezing onset temperatures and the abundance of ice nuclei in suspensions of washed spores. Microbiological analyses of spores from France, the USA and Brazil, and subsequent tests of the ice nucleation activity of the bacteria associated with spores were deployed to quantify the contribution of bacteria to the ice nucleation activity of the spores. All samples of spores were ice nucleation active, having freezing onset temperatures as high as −4 °C. Spores in most of the samples carried cells of ice nucleation-active strains of the bacterium Pseudomonas syringae (at rates of less than 1 bacterial cell per 100 urediospores), but bacterial INA accounted for only a small fraction of the INA observed in spore suspensions. Changes in the INA of spore suspensions after treatment with lysozyme suggest that the INA of urediospores involves a polysaccharide. Based on data from the literature, we have estimated the concentrations of urediospores in air at cloud height and in rainfall. These quantities are very similar to those reported for other biological ice nucleators in these same substrates. However, at cloud level convective activity leads to widely varying concentrations of particles of surface origin, so that mean concentrations can underestimate their possible effects on clouds. We propose that spatial and temporal concentrations of biological ice nucleators active at temperatures > −10 °C and the specific conditions under which they can influence cloud glaciation need to be further evaluated so as to understand how evolutionary processes could have positively selected for INA.

scholarly journals Survival and ice nucleation activity ofPseudomonas syringaestrains exposed to simulated high-altitude atmospheric conditions

2018 ◽  
Author(s):  
Gabriel Guarany de Araujo ◽  
Fabio Rodrigues ◽  
Fabio Luiz Teixeira Gonçalves ◽  
Douglas Galante
Keyword(s):  
Pseudomonas Syringae ◽  
Water Samples ◽  
Cloud Water ◽  
Ice Nucleation ◽  
Important Process ◽  
High Altitudes ◽  
Ice Nuclei ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

ABSTRACTThe epiphytic bacteriumPseudomonas syringaeproduces the most efficient and well-studied biological ice nuclei (IN) known. Bioaerosols containing these cells have been proposed to influence cloud glaciation, an important process in the initiation of precipitation. The presence of this species has been reported on rain, snow, and cloud water samples, but how these organisms can survive the harsh conditions present on the high atmosphere still remains to be better understood. In this study, the impact caused by this type of environment onP. syringaewas assayed by measuring their viability and IN activity. Two strains, of the pathovarssyringaeandgarcae, were compared toEscherichia coli.While UV-C radiation effectively inactivated these cells, thePseudomonaswere much more tolerant to UV-B. TheP. syringaestrains were also more resistant to “environmental” UV radiation from a solar simulator, composed of UV-A and UV-B. The response of their IN after long exposures to this radiation varied: only one strain suffered a relatively small 10-fold reduction in IN activity at -5 °C. Desiccation at different relative humidity values also affected the IN, but some activity at -5 °C was still maintained for all tests. The pathovargarcaetended to be more resistant to the stress treatments than the pathovarsyringae, particularly to desiccation, though its IN were found to be more sensitive. Compared toE. coli, theP. syringaestrains seemed relatively better adapted to survival under conditions present on the atmosphere at high altitudes.IMPORTANCEThe plant-associated bacteriumPseudomonas syringaeproduces on its outer membrane highly efficient ice nuclei which are able to induce the freezing of supercooled water. This ability has been linked to increased frost damaged on colonized leaves and also to the formation of ice in clouds, an important process leading to precipitation.P. syringaehas been found on rain, snow, and cloud water samples, confirming its presence on the atmosphere. This study aimed to assess the survival of these cells and the maintenance of their ice nucleation activity under stressing conditions present in high altitudes: ultraviolet radiation and desiccation.P. syringaestrains were shown to at least partially tolerate these factors, and their most efficient ice nuclei, while affected, could still be detected after all experiments.

scholarly journals Twin-plate Ice Nucleation Assay (TINA) with infrared detection for high-throughput droplet freezing experiments with biological ice nuclei in laboratory and field samples

2018 ◽  
Vol 11 (11) ◽  
pp. 6327-6337 ◽  
Author(s):  
Anna T. Kunert ◽  
Mark Lamneck ◽  
Frank Helleis ◽  
Ulrich Pöschl ◽  
Mira L. Pöhlker ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
High Throughput ◽  
Atmospheric Aerosols ◽  
Cooling System ◽  
Infrared Detector ◽  
Ice Nucleation ◽  
Cumulative Number ◽  
Ice Nuclei ◽  
Wide Range ◽  
Field Samples

Abstract. For efficient analysis and characterization of biological ice nuclei under immersion freezing conditions, we developed the Twin-plate Ice Nucleation Assay (TINA) for high-throughput droplet freezing experiments, in which the temperature profile and freezing of each droplet is tracked by an infrared detector. In the fully automated setup, a couple of independently cooled aluminum blocks carrying two 96-well plates and two 384-well plates, respectively, are available to study ice nucleation and freezing events simultaneously in hundreds of microliter-range droplets (0.1–40 µL). A cooling system with two refrigerant circulation loops is used for high-precision temperature control (uncertainty <0.2 K), enabling measurements over a wide range of temperatures (∼ 272–233 K) at variable cooling rates (up to 10 K min−1). The TINA instrument was tested and characterized in experiments with bacterial and fungal ice nuclei (IN) from Pseudomonas syringae (Snomax®) and Mortierella alpina, exhibiting freezing curves in good agreement with literature data. Moreover, TINA was applied to investigate the influence of chemical processing on the activity of biological IN, in particular the effects of oxidation and nitration reactions. Upon exposure of Snomax® to O3 and NO2, the cumulative number of IN active at 270–266 K decreased by more than 1 order of magnitude. Furthermore, TINA was used to study aqueous extracts of atmospheric aerosols, simultaneously investigating a multitude of samples that were pre-treated in different ways to distinguish different kinds of IN. For example, heat treatment and filtration indicated that most biological IN were larger than 5 µm. The results confirm that TINA is suitable for high-throughput experiments and efficient analysis of biological IN in laboratory and field samples.

scholarly journals Annual Spread Rate of Tomentosus Root Disease

Plant Disease ◽  
1997 ◽  
Vol 81 (9) ◽  
pp. 1053-1056 ◽  
Author(s):  
R. S. Hunt ◽  
F. G. Peet
Keyword(s):  
British Columbia ◽  
Tree Ring ◽  
Root Disease ◽  
Uninfected Control ◽  
Radial Increment ◽  
Spread Rate ◽  
Annual Increment ◽  
Temporal Differences ◽  
The Difference ◽  
A New Technique

The spread rate of tomentosus root disease, caused by Inonotus tomentosus, was investigated by a new technique employing temporal differences in the initiation of the reduced annual radial increment between pairs of diseased trees. Pairs of infected trees (stumps) located on the periphery of disease centers were selected in each of six widely separated spruce (Picea spp.) stands in British Columbia. Distances between 12 pairs of stumps were measured, and disks were collected from each stump. Similarly, disks from four additional pairs were collected from trees in a younger stand. Uninfected control disks were collected for all sites. Tree-ring measurements were determined for all disk samples and the year in which the reduction of the annual increment attributable to I. tomentosus began was determined for infected trees. The difference between initiation years for pairs of infected trees divided into the distance between them produced an average annual spread rate of 20 cm/yr. This rate will be used in developing a model for the disease.

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