title: Do ice nucleating lipoproteins protect frozen insects against toxic chemical agents?
abstract: As the body fluid of freeze-tolerant organisms freezes, solutes become concentrated in the gradually smaller unfrozen fluid fraction, and dissolved trace metals may reach toxic levels. A dialysis technique was used to investigate the metal binding capacity of the low density fraction of the hemolymph from the freeze tolerant beetle Phyto depressus. The low density fraction, assumed to contain the ice nucleating lipoproteins, showed approximately 100 times greater capacity to bind metals (Cd (2+), Cu (2+) and Zn (2+)) than the proteins albumin, hemoglobin and similar to metallothionein. The high metal binding capacity in the low density fraction raises the question if the ice nucleating lipoproteins might assist in detoxification of potentially toxic concentrations of metals that may occur when a large fraction of the bodyfluids of freeze tolerant insects freeze. This hypotheis is consistent with the fact that the lipoprotein ice nucleators are present in far greater amounts than required for ice nucleation, and also with the fact that the lipoprotein ice nucleators have a remarkably high content of amino acids with negatively charged residues that may act as metal binding sites.
authors.affiliation: Faculty of Biology and Pharmacy, Friedrich Schiller University of Jena, DE-07743 Jena, Germany. jtrautsch@ice.mpg.de
authors.forename: Janett
authors.initials: J
authors.lastname: Trautsch
authors.forename: Bjørn Olav
authors.initials: BO
authors.lastname: Rosseland
authors.forename: Sindre Andre
authors.initials: SA
authors.lastname: Pedersen
authors.forename: Erlend
authors.initials: E
authors.lastname: Kristiansen
authors.forename: Karl Erik
authors.initials: KE
authors.lastname: Zachariassen
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000378:metabolism*; D005615:Freezing; D008658:Inactivation, Metabolic; D019476:Insect Proteins / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D008074:Lipoproteins; D008670:Metals