scholarly journals Computational Assessment of Modified Antifreeze Glycoproteins on Ice Nucleation

Biophysica ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 168-178
Author(s):  
Monika Bleszynski ◽  
Matt Reil
Keyword(s):  
Separation Distance ◽  
Ice Nucleation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Antifreeze Glycoproteins ◽  
Crystallization Inhibition ◽  
Nucleation Activity ◽  
Dynamics Simulations ◽  
Ice Nucleation Activity ◽  
Ice Crystallization

Antifreeze glycoproteins (AFGPs) found in various fish are used by the organisms to prevent freezing. While these compounds have been studied for their ability to bind to, and prevent the complete crystallization of water, the exact mechanisms by which AFGPs prevent freezing are still undetermined. Therefore, building upon our previous work, this study uses molecular dynamics simulations to assess the effects of hydroxyl group separation distance on AFGP ice nucleation activity. Water droplet crystallization simulations showed that modified AFGP structures containing hydroxyl distances smaller than ~3.0 Å lost their ability to prevent ice crystallization. Furthermore, modified AFGP containing hydroxyl distances of 7.327 Å and 6.160 Å was correlated with a promotion in ice nucleation, as demonstrated by the changes in the energy of the system. This supports the notion that the distance, and therefore, geometry characteristics between the hydroxyl groups located on the saccharide structures play a key role in the ice crystallization inhibition properties of AFGP compounds.

scholarly journals Hydroxyl Group Separation Distances in Anti-Freeze Compounds and Their Effects on Ice Nucleation

2020 ◽  
Vol 21 (22) ◽  
pp. 8488
Author(s):  
Monika Bleszynski ◽  
Matt Reil ◽  
Maciej Kumosa
Keyword(s):  
Molecular Dynamics ◽  
Polyvinyl Alcohol ◽  
Synthetic Polymers ◽  
Separation Distance ◽  
Ice Nucleation ◽  
Hydroxyl Group ◽  
Group Separation ◽  
Antifreeze Glycoproteins ◽  
Key Factor ◽  
Dynamics Simulations

Since the discovery of biological antifreeze glycoproteins (AFGPs), which can inhibit ice nucleation, there has been considerable interest in understanding their mechanisms and mimicking them in synthetic polymers. In this study, we used molecular dynamics simulations of modified polyvinyl alcohol (PVA) compounds to show that the hydroxyl (OH) group distance is a key factor in whether certain compounds promote or inhibit ice nucleation. A hydroxyl distance smaller than ~2.8 Å but greater than ~7.1 Å in modified PVA (MPVA) compounds was associated with the promotion of ice nucleation, while a hydroxyl group separation distance of approximately ~5.0 Å was correlated with a delay in ice nucleation, owing to changes in the energy of the system. Thus, these results may help explain some of the mechanisms of current known anti-freeze compounds and may have implications for designing new anti-freeze compounds in the future.

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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