https://padlet.com/glorh823/tbl23i51o91w en-us 2019-03-12 12:01:09 UTC 2024-10-15 21:23:13 UTC hello@padlet.com glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341126419 Cryobiology deals with life at low temperature. The word cryobiology is relatively new, so it was first used in the early 1950s to describe the newly developing field of low temperature biology.  ]]> 2019-03-14 00:27:28 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341126419 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341129187 Yes. In generally, any biological science directly or indirectly connected with geology. This is because a lot of sedimentary rocks were originated under varying extents of influence of living organisms. In this case, we are interested in shuch a field of science where it is considered how organisms surveve at temperatures below normal. Below you can see the hierarchy of the sciences, which clearly shows the dependence of any science on the overlying.]]> 2019-03-14 00:42:07 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341129187 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341147205 There are such branches of cryobiology as:]]> 2019-03-14 02:02:10 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341147205 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341148543 There are, for example, trees whose twigs can survive direct immersion in liquid nitrogen after suitable pre-conditioning. They achieve this by manufacturing proteins and sugars that allow the cytoplasm to turn into a glass at temperatures about 30 to 40 degrees below zero; once the plant cells vitrify, they are immune to most low-temperature dangers.  Certain lichens are even more dazzling, vitrifying upon cooling and warming, without previous crystallization.
Another and even more prominent example is the freezable frog, a vertebrate that, along with certain turtles, snakes, and salamanders, has found a way of exposing all of its internal organs to severe freezing at relatively high temperatures (about -6(C) for weeks at a time with spontaneous recovery upon thawing.  It turns out that major elements in the success of these creatures are the elaboration of natural cryoprotective agents (especially glucose and glycerol, plus a plethora of less-significant agents) and the ability to control the location of ice, typically depositing most of it external to rather than inside the major organs.  Certain plants achieve the same control of ice by elaborating a physical barrier between sensitive areas (the apical meristems) and the location of ice formation, such that water can leave the meristems and deposit on ice in the ice-tolerant area, but ice cannot grow through the barrier to invade and thereby to kill the meristem.  The meristem can survive the dehydration, and so it survives the winter.
Perhaps the real champions of natural low-temperature survival (with the possible exception of bacteria and the like) are the insects, some of which can survive freezing to at least the temperature of dry ice (about -79 degrees C).]]> 2019-03-14 02:09:03 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341148543 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341149057 Freeze drying, also known as lyophilisation, is a low temperature dehytration process which involves freezing the product, lowering pressure, then removing the ice by sublimation.]]> 2019-03-14 02:12:07 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341149057 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341149182 Supercooling is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.  Whole-body supercooling allows many insects and fish to survive the winter. Supercooling is possible because the probability of spontaneous freezing is small in very small volumes (droplets of water), and because the droplets are prevented from touching each other by being dispersed in a non-aqueous phase as an emulsion (such a technique is used in British company, Pafra, Ltd.). Main condition of supercooling is lacking a seed crystal or nucleus around which a crystal structure can form.]]> 2019-03-14 02:12:38 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341149182 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341149286 Cryosurgery is considered a branch of cryobiology even though the object of cryosurgery is to kill cells rather than to preserve them. Cryosurgery works by exposing cells in the patient to very rapid cooling to deep subzero temperatures.  Rapid cooling, for basic physical reasons, causes water inside cells to freeze, whereas the slow cooling found in nature and usually used for cryopreservation causes intracellular water to leave cells and freeze extracellularly.  Intracellular freezing tends to be lethal, and its lethality is enhanced by slow warming, which allows intracellular ice to rearrange itself into a simpler structure, in the process literally grinding up the cellular interior.  Cryosurgery essentially involves localized rapid cooling to lethal temperatures followed by relatively slow warming and is used to eliminate unwanted cells such as tumor cells.]]> 2019-03-14 02:13:13 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341149286 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341149382 Frostbite is a form of slow freezing that can be as lethal as cryosurgery. Here the ice remains extracellular, but because there is no cryoprotective agent available, the extent of freezing exceeds tolerable limits.  The injury is mostly mechanical in nature but does not necessarily imply the death of cells in the frozen extremity.]]> 2019-03-14 02:13:52 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341149382 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341149516 Cryopreservation is a process where organs, tissues, cells, extracellural matrix or any other biological constructs susceptible to damage caused by unregulated chemical kinetics are preserved by cooling to very low temperatures (typically −80 °C using solid carbon dioxide or −196 °C using liquid nitrogen). At low enough temperatures, any enzymatic or chemical activity which might cause damage to the biological material is effectively stopped. Cryopreservation methods seek to reach low temperatures without causing additional damage caused by the formation of ice crystals during freezing. Traditional cryopreservation has relied on coating the material to be frozen with a class of molecules termed cryoprotectants. New methods are constantly being investigated due to the inherent toxicity of many cryoprotectants.]]> 2019-03-14 02:14:22 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341149516 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341156005 2019-03-14 02:57:54 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341156005 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341157072 The blue arrow points to the process of freezy-drying.]]> 2019-03-14 03:04:22 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341157072 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341165727 2019-03-14 04:05:38 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341165727 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341169289 2019-03-14 04:31:46 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341169289 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341169676 Cryobiosis is a form of cryptobiosis that takes place in reaction to decreased temperature. Cryobiosis initiates when the water surrounding the organism's cells has been frozen, stopping molecule mobility allows the organism to endure the freezing temperatures until more hospitable conditions return. Organisms capable of enduring these conditions typically feature molecules that facilitate freezing of water in preferential locations while also prohibiting the growth of large ice crystals that could otherwise damage cells. One such organism is the lobster.]]> 2019-03-14 04:34:38 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341169676 glorh823 https://padlet.com/glorh823/tbl23i51o91w/wish/341170202 2019-03-14 04:38:17 UTC https://padlet.com/glorh823/tbl23i51o91w/wish/341170202