Epiphytic populations of Pseudomonas syringae and Erwinia herbicola are important sources of ice nuclei that incite frost damage in agricultural crop plants. We have cloned and characterized DNA segments carrying the genes (ice) responsible for the ice-nucleating ability of these bacteria. The ice region spanned 3.5 to 4.0 kilobases and was continuous over this region in P. syringae Cit7R1. The...

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 ubiq...

The majority of overwintering insects avoid lethal freezing by lowering the temperature at which ice spontaneously nucleates within their body fluids. We examined the effect of ice-nucleating-active bacteria on the cold-hardiness of the lady beetle, Hippodamia convergens, a freeze-intolerant species that overwinters by supercooling to ca. -16 degrees C. Topical application of the ice-nucleating...

Since most insects are unable to survive internal ice formation a key factor in their overwintering survival is the regulation of the temperature at which they spontaneously freeze. To enhance their supercooling capacity overwintering insects eliminate endogenous ice nucleators, accumulate low-molecular-weight polyols and sugars, and synthesize hemolymph antifreeze proteins. A number of freeze-...

Large biases in climate model simulations of cloud radiative properties over the Southern Ocean cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated Southern Ocean clouds reflect far more...

During the autumn, the third-instar larvae of the gall fly Eurosta solidaginis acquire freeze tolerance and their crystallization temperatures increase into the -8 to -10 °C range. Despite conflicting reports, efficient endogenous ice nucleators have not been identified in this freeze-tolerant insect. We found large crystalloid spheres within the Malpighian tubules of overwintering larvae. ...

Several ice-nucleating bacterial strains, including Erwinia herbicola, Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for their ability to shed ice nuclei into the growth medium. Only E. herbicola isolates shed cell-free ice nuclei active at -2 to -10 degrees C. These cell-free nuclei exhibited a freezing spectrum similar to that of ice nuclei found on whole cells, bo...

In this chapter we formulate an ice active surface site based stochastic model of heterogeneous freezing with the unique feature of invoking a continuum assumption on the ice nucleating activity (contact angle) of an aerosol particle’s surface, that requires no assumptions about the size or number of active sites. The result is a particle specific property g that defines a distribution of local...

Some ice-nucleating bacterial strains, including Pantoea ananatis (Erwinia uredovora), Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for the ability to shed ice nuclei into the growth medium. A novel ice-nucleating bacterium, Pseudomonas antarctica IN-74, was isolated from Ross Island, Antarctica. Cell-free ice nuclei from P. antarctica IN-74 were different from the ...

plates, and we made a general statement that an electric field mechanism helps align the water molecules into ice-like clusters. Thus, our analysis does not involve the difference in energy between "ice" and "water" but is rather a comparison of the interaction energy of the polar substrate crystal with an ice nucleus (partially) proton-ordered along the hexagonal axis as against a nonpolar sub...