Birch leaves and branches as a source of ice-nucleating macromolecules

Abstract

Abstract. Birch pollen are known to release ice-nucleating macromolecules (INM), but little is known about the production and release of INM from other parts of the tree. We examined the ice nucleation activity of samples from 10 different birch trees (Betula spp.). Samples were taken from nine birch trees in Tyrol, Austria, and from one tree in a small urban park in Vienna, Austria. Filtered aqueous extracts of 30 samples of leaves, primary wood (new branch wood, green in colour, photosynthetically active), and secondary wood (older branch wood, brown in colour, with no photosynthetic activity) were analysed in terms of ice nucleation activity using VODCA (Vienna Optical Droplet Crystallization Analyser), a cryo microscope for emulsion samples. All samples contained ice-nucleating particles in the submicron size range. Concentrations of ice nuclei ranged from 6.7×104 to 6.1×109 mg−1 sample. Mean freezing temperatures varied between −15.6 and −31.3 ∘C; the range of temperatures where washes of birch pollen and dilutions thereof typically freeze. The freezing behaviour of three concentrations of birch pollen washing water (initial wash, 1 : 100, and 1 : 10 000) were significantly associated with more than a quarter of our samples, including some of the samples with highest and lowest activity. This indicates a relationship between the INM of wood, leaves, and pollen. Extracts derived from secondary wood showed the highest concentrations of INM and the highest freezing temperatures. Extracts from the leaves exhibited the highest variation in INM and freezing temperatures. Infrared spectra of the extracts and tested birch samples show qualitative similarity, suggesting the chemical components may be broadly similar.

Development of the DRoplet Ice Nuclei Counter Zurich (DRINCZ): validation and application to field-collected snow samples

“…Back trajectories indicate that the air mass source region and the amount of upstream precipitation differed between the two sectors of the cyclone. This result is consistent with previous studies that suggest that air mass origin (e.g., Ault et al, 2011;Creamean et al, 2013;Field et al, 2006;Lacher et al, 2017Lacher et al, , 2018 and upstream precipitation (Stopelli et al, 2015) influence the INP concentration. Furthermore, the dependence on the long-range air mass history to the observed variability in n mw suggests that local sources are not responsible for the observed INPs.…”

Macromolecular fungal ice nuclei in <i>Fusarium</i>: effects of physical and chemical processing

“…Fusarium concentricum is a plant pathogen, which is frequently found in Central America and isolated from bananas (Aoki et al, 2001;Leslie and Summerell, 2006), and F. langsethiae is a broadly distributed cereal pathogen (Torp and Nirenberg, 2004). Some strains of these newly identified IN-active species are known to produce mycotoxins, which can threaten the health of humans and animals (Fotso et al, 2012;Kokkonen et al, 2012;Wing et al, 1993a, b).…”

Protein aggregates nucleate ice: the example of apoferritin

“…Alternatively, cloud droplets may freeze while they come in contact with an INP (contact freezing) or while an INP activates to a cloud droplet (condensation freezing) (Murray et al, 2012;Vali et al, 2015;Kanji et al, 2017). After the formation of the first ice crystals, cloud glaciation may proceed through additional primary ice nucleation occurring on INPs that become active at lower temperatures, ice crystal multiplication (Hallett and Mossop, 1974;Yano and Phillips, 2011;Crawford et al, 2012;Lauber et al, 2018;Field et al, 2017), and the Wegener-Bergeron-Findeisen process (Wegener, 1911;Bergeron, 1928;Findeisen, 1938;Korolev, 2007;Korolev and Field, 2008).…”