Ice nucleation and antinucleation in nature

Plants and ectothermic animals use a variety of substances and mechanisms t o survive exposure to subfreezing temperatures. Proteinaceous ice nucleator s trigger freezing at high subzero temperatures, either to provide cold pro tection from released heat of fusion or to establish a protective extracell ular freezing in freeze-tolerant species. Freeze-avoiding species increase their supercooling potential by removing ice nucleators and accumulating po lyols. Terrestrial invertebrates and polar marine fish stabilize their supe rcooled state by means of noncolligatively acting antifreeze proteins. Some organisms also depress their body fluid melting point to ambient temperatu re by evaporation and/or solute accumulation. (C) 2000 Academic Press.