scholarly journals A novel view on the mechanism of biological activity of antifreeze proteins

2021 ◽  
Author(s):  
Bogdan S Melnik ◽  
Ksenia A Glukhova ◽  
Evgeniya A Sokolova ◽  
Irina V Balalaeva ◽  
Alexei V Finkelstein
Keyword(s):  
Antifreeze Proteins ◽  
Freezing Temperature ◽  
Bulk Water ◽  
Ice Crystals ◽  
Ice Formation ◽  
Common Belief ◽  
Ice Melting ◽  
Cell Surfaces ◽  
Ice Nuclei ◽  
Ice Binding

The adaptation of organisms to sub-zero temperatures is an intriguing problem in biology and biotechnology. The ice-binding antifreeze proteins are known to be responsible for the adaptation, but the mechanism of their action is still far from being clear. Here we show that: (i) in contrast to common belief, ice-binding proteins do not reduce the water freezing temperature and even raise the ice melting point; (ii) at sub-zero temperatures (to −30°C), ice can be formed only on ice-binding surfaces, but, for kinetic reasons, not in bulk water; (iii) living cells have some large surfaces, which can bind the antifreeze proteins. These facts allow suggesting that the task of antifreeze proteins is not to bind to the ice crystals already formed in the cell and stop their growth or rearrangement, but to bind to those cell surfaces where the ice nuclei can form, and thus to prevent ice formation completely.

scholarly journals Janus effect of antifreeze proteins on ice nucleation

2016 ◽  
Vol 113 (51) ◽  
pp. 14739-14744 ◽  
Author(s):  
Kai Liu ◽  
Chunlei Wang ◽  
Ji Ma ◽  
Guosheng Shi ◽  
Xi Yao ◽  
...  
Keyword(s):  
Liquid Water ◽  
Molecular Level ◽  
Simulation Analysis ◽  
Antifreeze Proteins ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Dynamics Simulation ◽  
Ice Binding ◽  
Solid Substrates ◽  
Unique Capability

The mechanism of ice nucleation at the molecular level remains largely unknown. Nature endows antifreeze proteins (AFPs) with the unique capability of controlling ice formation. However, the effect of AFPs on ice nucleation has been under debate. Here we report the observation of both depression and promotion effects of AFPs on ice nucleation via selectively binding the ice-binding face (IBF) and the non–ice-binding face (NIBF) of AFPs to solid substrates. Freezing temperature and delay time assays show that ice nucleation is depressed with the NIBF exposed to liquid water, whereas ice nucleation is facilitated with the IBF exposed to liquid water. The generality of this Janus effect is verified by investigating three representative AFPs. Molecular dynamics simulation analysis shows that the Janus effect can be established by the distinct structures of the hydration layer around IBF and NIBF. Our work greatly enhances the understanding of the mechanism of AFPs at the molecular level and brings insights to the fundamentals of heterogeneous ice nucleation.

scholarly journals Ice formation and development in aged, wintertime cumulus over the UK: observations and modelling

2012 ◽  
Vol 12 (11) ◽  
pp. 4963-4985 ◽  
Author(s):  
I. Crawford ◽  
K. N. Bower ◽  
T. W. Choularton ◽  
C. Dearden ◽  
J. Crosier ◽  
...  
Keyword(s):  
Particle Production ◽  
Ice Crystals ◽  
Dust Particles ◽  
Ice Formation ◽  
Crystal Formation ◽  
Surface Acting ◽  
Model Simulations ◽  
Ice Nuclei ◽  
Ice Particles ◽  
High Concentrations

Abstract. In situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of a line of small cumulus clouds, using Radar and Lidar, as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than −8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed, near cloud top, temperatures (−7.5 °C). The role of mineral dust particles, consistent with concentrations observed near the surface, acting as high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L−1) could be produced by secondary ice particle production providing the observed small amount of primary ice (about 0.01 L−1) was present to initiate it. This emphasises the need to understand primary ice formation in slightly supercooled clouds. It is shown using simple calculations that the Hallett-Mossop process (HM) is the likely source of the secondary ice. Model simulations of the case study were performed with the Aerosol Cloud and Precipitation Interactions Model (ACPIM). These parcel model investigations confirmed the HM process to be a very important mechanism for producing the observed high ice concentrations. A key step in generating the high concentrations was the process of collision and coalescence of rain drops, which once formed fell rapidly through the cloud, collecting ice particles which caused them to freeze and form instant large riming particles. The broadening of the droplet size-distribution by collision-coalescence was, therefore, a vital step in this process as this was required to generate the large number of ice crystals observed in the time available. Simulations were also performed with the WRF (Weather, Research and Forecasting) model. The results showed that while HM does act to increase the mass and number concentration of ice particles in these model simulations it was not found to be critical for the formation of precipitation. However, the WRF simulations produced a cloud top that was too cold and this, combined with the assumption of continual replenishing of ice nuclei removed by ice crystal formation, resulted in too many ice crystals forming by primary nucleation compared to the observations and parcel modelling.

The Mystery of Ice Crystal Multiplication in a Laboratory Experiment

2013 ◽  
Vol 71 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Gianni Santachiara ◽  
Franco Belosi ◽  
Franco Prodi
Keyword(s):  
Laboratory Experiment ◽  
Supercooled Liquid ◽  
Ice Crystals ◽  
Formation Processes ◽  
Ice Crystal ◽  
Droplet Vaporization ◽  
Ice Nuclei ◽  
Cold Room ◽  
The Mean ◽  
Ice Multiplication

Abstract This paper addresses the problem of the large discrepancies between ice crystal concentrations in clouds and the number of ice nuclei in nearby clear air reported in published papers. Such discrepancies cannot always be explained, even by taking into account both primary and secondary ice formation processes. A laboratory experiment was performed in a cylindrical column placed in a cold room at atmospheric pressure and temperature in the −12° to −14°C range. Supercooled droplets were nucleated in the column, in the absence of aerosol ice nuclei, by injecting ice crystals generated outside in a small syringe. A rapid increase in the ice crystal concentration was observed in the absence of any known ice multiplication. The ratio between the mean number of ice crystals in the column, after complete droplet vaporization, and the number of ice crystals introduced in the column was about 10:1. The presence of small ice crystals (introduced at the top of the column) in the unstable system (supercooled droplets) appears to trigger the transformation in the whole supercooled liquid cloud. A possible explanation could be that the rapidly evaporating droplets cool sufficiently to determine a homogeneous nucleation.

scholarly journals Condensed-phase biogenic–anthropogenic interactions with implications for cold cloud formation

2017 ◽  
Vol 200 ◽  
pp. 165-194 ◽  
Author(s):  
Joseph C. Charnawskas ◽  
Peter A. Alpert ◽  
Andrew T. Lambe ◽  
Thomas Berkemeier ◽  
Rachel E. O’Brien ◽  
...  
Keyword(s):  
Freezing Temperature ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Fossil Fuel Combustion ◽  
Soot Particles ◽  
Ice Nuclei ◽  
Deliquescence Relative Humidity ◽  
Homogeneous Freezing

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (Tg) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveTgand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

scholarly journals Measurements of Ice Nucleating Particles and Ice Residuals

2017 ◽  
Vol 58 ◽  
pp. 8.1-8.13 ◽  
Author(s):  
Daniel J. Cziczo ◽  
Luis Ladino ◽  
Yvonne Boose ◽  
Zamin A. Kanji ◽  
Piotr Kupiszewski ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Condensed Phase ◽  
Atmospheric Aerosols ◽  
Aerosol Particles ◽  
Ice Crystals ◽  
Ice Formation ◽  
Similar Amount ◽  
Residual Material ◽  
History Of ◽  
Phase Water

Abstract It has been known that aerosol particles act as nuclei for ice formation for over a century and a half (see Dufour). Initial attempts to understand the nature of these ice nucleating particles were optical and electron microscope inspection of inclusions at the center of a crystal (see Isono; Kumai). Only within the last few decades has instrumentation to extract ice crystals from clouds and analyze the residual material after sublimation of condensed-phase water been available (see Cziczo and Froyd). Techniques to ascertain the ice nucleating potential of atmospheric aerosols have only been in place for a similar amount of time (see DeMott et al.). In this chapter the history of measurements of ice nucleating particles, both in the field and complementary studies in the laboratory, are reviewed. Remaining uncertainties and artifacts associated with measurements are described and suggestions for future areas of improvement are made.

scholarly journals Ice nucleation efficiency of AgI: review and new insights

2016 ◽  
Author(s):  
Claudia Marcolli ◽  
Baban Nagare ◽  
André Welti ◽  
Ulrike Lohmann
Keyword(s):  
Water Saturation ◽  
Experimental Studies ◽  
Freezing Temperature ◽  
Nucleating Agent ◽  
Companion Paper ◽  
Chem Phys ◽  
Ice Nucleation ◽  
Lattice Match ◽  
Ice Nuclei ◽  
Immersion Freezing

Abstract. AgI is one of the best investigated ice nuclei. It has relevance for the atmosphere since it is used for glaciogenic cloud seeding. Theoretical and experimental studies over the last sixty years provide a complex picture of silver iodide as ice nucleating agent with conflicting and inconsistent results. This review compares experimental ice nucleation studies in order to analyse the factors that influence the ice nucleation ability of AgI. We have performed experiments to compare contact and immersion freezing by AgI. This is one of three papers that describe and analyse contact and immersion freezing experiments with AgI. In Nagare et al. (Nagare, B., Marcolli, C., Stetzer, O., and Lohmann, U.: Comparison of measured and calculated collision efficiencies at low temperatures, Atmos. Chem. Phys., 15, 13759–13776, doi:10.5194/acp-15-13759-2015, 2015) collision efficiencies based on contact freezing experiments with AgI are determined and compared with theoretical formulations. In a companion paper, contact freezing experiments are compared with immersion freezing experiments conducted with AgI, kaolinite, and ATD as ice nuclei. The following picture emerges from this analysis: The ice nucleation ability of AgI seems to be enhanced when the AgI particle is on the surface of a droplet, which is indeed the position that a particle takes when it can freely move in a droplet. Ice nucleation by particles with surfaces exposed to air, depends on water adsorption. AgI surfaces seem to be most efficient as ice nuclei when they are exposed to relative humidity at or even above water saturation. For AgI particles that are totally immersed in water, the freezing temperature increases with increasing AgI surface area. Higher threshold freezing temperature seem to correlate with improved lattice matches as can be seen for AgI-AgCl solid solutions and 3AgI•NH4I•6H2O, which have slightly better lattice matches with ice than AgI and also higher threshold freezing temperatures. However, the effect of a good lattice match is annihilated when the surfaces have charges. Also, the ice nucleation ability seems to decrease during dissolution of AgI particles. This introduces an additional history and time dependence of ice nucleation in cloud chambers with short residence times.

Fish Antifreeze Proteins: Recent Gene Evolution

1986 ◽  
Vol 43 (5) ◽  
pp. 1028-1034 ◽  
Author(s):  
Gary K. Scott ◽  
Garth L. Fletcher ◽  
Peter L. Davies
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Genomic Organization ◽  
Gene Evolution ◽  
Antifreeze Proteins ◽  
Gene Organization ◽  
Ice Formation ◽  
Polar Regions ◽  
Subzero Temperatures ◽  
Combining Evidence

A variety of antifreeze proteins is produced by marine teleosts inhabiting polar regions to ensure protection from internal ice formation at subzero temperatures. Combining evidence from paleoclimatology, teleostian evolution, and studies of antifreeze gene organization, the case is made for Cenozoic cooling as the force driving antifreeze evolution in marine teleosts. The distribution of antifreeze types amongst teleost suborders, families, genera, and species correlates with Cenozoic glaciation in the Southern Hemisphere preceding that in the Northern Hemisphere by approximately 25 million yr. The genomic organization of antifreeze genes suggests recent and extensive amplification, an event compatible with their proposed stress-induced origin. Also, a realignment of the nototheniids with the Gadiformes based on antifreeze protein data is suggested.

scholarly journals Modelling of cirrus clouds – Part 2: Competition of different nucleation mechanisms

2009 ◽  
Vol 9 (7) ◽  
pp. 2319-2334 ◽  
Author(s):  
P. Spichtinger ◽  
K. M. Gierens
Keyword(s):  
Temperature Fluctuations ◽  
Cirrus Clouds ◽  
Ice Formation ◽  
Microphysics Scheme ◽  
Ice Nuclei ◽  
Nucleation Mechanisms ◽  
Sensitivity Studies ◽  
Random Motions ◽  
Cloud Evolution ◽  
Cloud Ice

Abstract. We study the competition of two different freezing mechanisms (homogeneous and heterogeneous freezing) in the same environment for cold cirrus clouds. To this goal we use the recently developed and validated ice microphysics scheme (Spichtinger and Gierens, 2009a) which distinguishes between ice classes according to their formation process. We investigate cases with purely homogeneous ice formation and compare them with cases where background ice nuclei in varying concentration heterogeneously form ice prior to homogeneous nucleation. We perform additionally a couple of sensitivity studies regarding threshold humidity for heterogeneous freezing, uplift speed, and ambient temperature, and we study the influence of random motions induced by temperature fluctuations in the clouds. We find three types of cloud evolution, homogeneously dominated, heterogeneously dominated, and a mixed type where neither nucleation process dominates. The latter case is prone to long–lasting in–cloud ice supersaturation of the order 30% and more.

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