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The relevance of nanoscale biological fragments for ice nucleation in clouds.

O'Sullivan D, Murray BJ, Ross JF, Whale TF, Price HC, Atkinson JD, Umo NS, Webb ME - Sci Rep (2015)

Bottom Line: However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds.In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample.Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles.

View Article: PubMed Central - PubMed

Affiliation: Institute for Climate and Atmospheric Science, School of Earth &Environment, University of Leeds, UK.

ABSTRACT
Most studies of the role of biological entities as atmospheric ice-nucleating particles have focused on relatively rare supermicron particles such as bacterial cells, fungal spores and pollen grains. However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds. Here we show that the ice-nucleating activity of a fungus from the ubiquitous genus Fusarium is related to the presence of nanometre-scale particles which are far more numerous, and therefore potentially far more important for cloud glaciation than whole intact spores or hyphae. In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample. Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles.

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Size exclusion chromatography combined with an ice nucleation assay to study the size of INPs in the fungus Fusarium avenaceum.(Left) Experimental schematic of the fractionation procedure. Initially, 96 × 300 μL fractions are collected from the Superose 6 10/300 GL column. A droplet freezing experiment is then performed using a 1 μL droplet from each of the fractions. (Right) UV absorbance (black trace) and freezing temperature of eluted fractions (blue trace) after passing through a Superose 6 column. The appearance of elevated nucleation temperatures can be seen concurrent to elevated absorbance in the eluate at flow through volumes of 6–11 mls (~1000–5000+ kDa).
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f3: Size exclusion chromatography combined with an ice nucleation assay to study the size of INPs in the fungus Fusarium avenaceum.(Left) Experimental schematic of the fractionation procedure. Initially, 96 × 300 μL fractions are collected from the Superose 6 10/300 GL column. A droplet freezing experiment is then performed using a 1 μL droplet from each of the fractions. (Right) UV absorbance (black trace) and freezing temperature of eluted fractions (blue trace) after passing through a Superose 6 column. The appearance of elevated nucleation temperatures can be seen concurrent to elevated absorbance in the eluate at flow through volumes of 6–11 mls (~1000–5000+ kDa).

Mentions: To further examine the size of the ice-nucleating particles generated by F. avenaceum, the 1000 kDa filtrate was separated into 96 size-resolved fractions using size-exclusion chromatography (Figure 3, left). This technique separates suspended particles on the basis of size, with smaller particles being eluted at later times (or larger elution volumes). When the ice nucleating activity of the fractions was examined, those with higher nucleation temperatures were found to correspond to fractions exhibiting a peak in the 280 nm UV absorbance (Figure 3, right), consistent with the INPs being proteinaceous. While all fractions were found to freeze at temperatures above −11°C, the highest freezing temperatures observed can be seen to appear concurrent with a fully resolved broad feature on the chromatogram at short retention times (eluate volume 6–11 mls). Of note, while a species of this size (~1000–5000+ kDa; dsmooth sphere = 13–23+ nm) is larger than the nominal molecular weight cut-off of the filter applied prior to size exclusion chromatography, this is consistent with a finite distribution of pore sizes as is found in ultrafiltration membranes25.


The relevance of nanoscale biological fragments for ice nucleation in clouds.

O'Sullivan D, Murray BJ, Ross JF, Whale TF, Price HC, Atkinson JD, Umo NS, Webb ME - Sci Rep (2015)

Size exclusion chromatography combined with an ice nucleation assay to study the size of INPs in the fungus Fusarium avenaceum.(Left) Experimental schematic of the fractionation procedure. Initially, 96 × 300 μL fractions are collected from the Superose 6 10/300 GL column. A droplet freezing experiment is then performed using a 1 μL droplet from each of the fractions. (Right) UV absorbance (black trace) and freezing temperature of eluted fractions (blue trace) after passing through a Superose 6 column. The appearance of elevated nucleation temperatures can be seen concurrent to elevated absorbance in the eluate at flow through volumes of 6–11 mls (~1000–5000+ kDa).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308702&req=5

f3: Size exclusion chromatography combined with an ice nucleation assay to study the size of INPs in the fungus Fusarium avenaceum.(Left) Experimental schematic of the fractionation procedure. Initially, 96 × 300 μL fractions are collected from the Superose 6 10/300 GL column. A droplet freezing experiment is then performed using a 1 μL droplet from each of the fractions. (Right) UV absorbance (black trace) and freezing temperature of eluted fractions (blue trace) after passing through a Superose 6 column. The appearance of elevated nucleation temperatures can be seen concurrent to elevated absorbance in the eluate at flow through volumes of 6–11 mls (~1000–5000+ kDa).
Mentions: To further examine the size of the ice-nucleating particles generated by F. avenaceum, the 1000 kDa filtrate was separated into 96 size-resolved fractions using size-exclusion chromatography (Figure 3, left). This technique separates suspended particles on the basis of size, with smaller particles being eluted at later times (or larger elution volumes). When the ice nucleating activity of the fractions was examined, those with higher nucleation temperatures were found to correspond to fractions exhibiting a peak in the 280 nm UV absorbance (Figure 3, right), consistent with the INPs being proteinaceous. While all fractions were found to freeze at temperatures above −11°C, the highest freezing temperatures observed can be seen to appear concurrent with a fully resolved broad feature on the chromatogram at short retention times (eluate volume 6–11 mls). Of note, while a species of this size (~1000–5000+ kDa; dsmooth sphere = 13–23+ nm) is larger than the nominal molecular weight cut-off of the filter applied prior to size exclusion chromatography, this is consistent with a finite distribution of pore sizes as is found in ultrafiltration membranes25.

Bottom Line: However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds.In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample.Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles.

View Article: PubMed Central - PubMed

Affiliation: Institute for Climate and Atmospheric Science, School of Earth &Environment, University of Leeds, UK.

ABSTRACT
Most studies of the role of biological entities as atmospheric ice-nucleating particles have focused on relatively rare supermicron particles such as bacterial cells, fungal spores and pollen grains. However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds. Here we show that the ice-nucleating activity of a fungus from the ubiquitous genus Fusarium is related to the presence of nanometre-scale particles which are far more numerous, and therefore potentially far more important for cloud glaciation than whole intact spores or hyphae. In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample. Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles.

Show MeSH