Biology at low temperature: Polge-Smith-Parkes glycerol cryoprotection; ice nucleation and vitrification; DMSO/glycerol/trehalose cryoprotectants; fish, insect and plant antifreeze proteins; LEA proteins; tardigrade cryptobiosis; wood-frog…
Cryobiology
Polge-Smith-Parkes glycerol cryopreservation
Polge-Smith-Parkes 1949 Nature 164:666; accidental discovery of glycerol cryoprotection of fowl spermatozoa; founded modern mammalian…
Ice nucleation in cells
Heterogeneous nucleation in supercooled aqueous media (~-12 C in cells) vs homogeneous (~-38 C in pure water); cryoprotectants depress and…
Vitrification (glass transition)
High cryoprotectant concentrations (>40%) plus rapid cooling form a non-crystalline amorphous glass below glass-transition temperature;…
DMSO cryoprotectant
Lovelock-Bishop 1959 Nature; dimethyl-sulfoxide identified as permeating cryoprotectant; now standard for stem cell, oocyte, and tissue…
Glycerol cryoprotectant
Slowly permeating cryoprotectant; classical for sperm and red-cell cryopreservation; depresses freezing point, raises bound water, reduces…
Trehalose anhydrobiosis
Crowe et al; nematodes, brine-shrimp cysts, tardigrades accumulate trehalose under desiccation; vitrifies cytoplasm and replaces water…
Antifreeze glycoprotein (fish)
DeVries 1969 Science; Antarctic notothenioid AFGPs depress freezing point non-colligatively by binding ice surfaces; thermal hysteresis ~1…
Insect antifreeze protein
Tenebrio molitor and Dendroides AFPs; thermal hysteresis up to ~5 C; threonine-rich ice-binding face; substantially more potent than fish…
Plant cold acclimation (CBF/DREB)
Thomashow CBF/DREB transcription factors; rapidly induced by low temperature; activate COR-gene battery; confer freezing tolerance in…
LEA proteins (late-embryogenesis-abundant)
Hand et al; intrinsically disordered LEA proteins accumulate in desiccating seeds and anhydrobiotic animals; act as molecular shield,…
Tardigrade cryptobiosis
Tardigrades withstand vacuum, ionising radiation, freezing to <-200 C and >150 C in anhydrobiotic state; CAHS/SAHS proteins and trehalose…
Wood-frog glucose cryoprotection
Storey-Storey; Rana sylvatica freezes ~65% body water in winter; liver glycogen rapidly mobilised to glucose, reaching ~250 mM and acting…
Mazur two-factor injury hypothesis
Mazur 1984; cryoinjury arises from slow-cooling solute concentration / dehydration AND fast-cooling intracellular ice formation; optimum…
Optimal cooling rate
Cell-type-specific U-shaped survival vs cooling-rate curve; sperm and red cells fast, embryos and oocytes slow; balance between dehydration…
Organ vitrification (Fahy-Wowk)
Fahy-Wowk; vitrification of whole organs (kidney, liver) using high-concentration cryoprotectant cocktails M22 plus rapid cooling; partial…
Cryo-EM vitrification (Dubochet)
Dubochet 1981; plunge-freeze biological samples into liquid ethane to vitrify water without crystallisation; structural-biology revolution;…
Ice-recrystallisation inhibition (IRI)
Antifreeze proteins suppress ice-crystal coalescence during warming/storage; primary mechanism in cryopreserved tissues; quantified by…
Cryonics
Low-temperature preservation of legally dead bodies in hopes of future revival; not a currently demonstrable medical procedure; small…