ikki
criticality distinguishes the ensemble of biological regulatory networks
bryan c. daniels et al. 2018
http://dx.doi.org/10.1103/PhysRevLett.121.138102
an extensively glycosylated archaeal pilus survives extreme conditions
fengbin wang et al. 2019
http://dx.doi.org/10.1038/s41564-019-0458-x
In certain acidic hot springs, even volcanic hot springs, live ancient single-celled organisms that can exist in conditions far too extreme for most forms of life. They have tiny appendages called pili that are so tough that they resisted UVA scientists' numerous efforts to break them apart to learn their secrets. "We were unable to take these things apart in boiling detergent. They just remained absolutely intact," said researcher Edward H. Egelman, PhD, of UVA's Department of Biochemistry and Molecular Genetics. "So we then tried much harsher treatments, including boiling them in lye, which is sodium hydroxide. Nope."
The researchers tried several other approaches before throwing up their hands and turning to cryo-electron microscopy, which allows them to image submicroscopic things almost down to individual atoms. What they found was shocking. "There's just a huge amount of sugar covering the entire surface of these filaments in a way that has never been seen before," Egelman said. "These bugs have devised a way to just use massive amounts of sugar to cover these filaments and make them resistant to the incredible extremes of the environment in which they live."
You might liken the sugar coating to a hard sugar shell on a candy apple. The outer sugar shell is much harder than what it surrounds. In this case, though, the sugars were arranged in such a stable fashion that even acid can't dissolve them.
"These pili, which are protein filaments, normally would be very sensitive to heat, acid and enzymes, but coating it in sugars make it almost indestructible," Egelman explained. "There's a lot of evidence showing that adding small numbers of sugars can increase the stability of drugs and other protein structures, but no one, as far as we know, has ever seen this massive amount ... to the point where something is almost indestructible."
People can take a lesson from nature's design to manufacture products that are similarly sturdy, Egelman said. Take a protein such as wool, say, and coat it in a special arrangement of sugars and you could make amazingly durable clothing, carpet or even building materials. "Proteins are pretty sturdy and resilient, but with this type of covering of sugar, they would be much more stable, even more resilient," Egelman said. "They could have lots of uses."
abstract Pili on the surface of Sulfolobus islandicus are used for many functions, and serve as receptors for certain archaeal viruses. The cells grow optimally at pH 3 and ~80 °C, exposing these extracellular appendages to a very harsh environment. The pili, when removed from cells, resist digestion by trypsin or pepsin, and survive boiling in sodium dodecyl sulfate or 5 M guanidine hydrochloride. We used electron cryo-microscopy to determine the structure of these filaments at 4.1 Å resolution. An atomic model was built by combining the electron density map with bioinformatics without previous knowledge of the pilin sequence—an approach that should prove useful for assemblies where all of the components are not known. The atomic structure of the pilus was unusual, with almost one-third of the residues being either threonine or serine, and with many hydrophobic surface residues. While the map showed extra density consistent with glycosylation for only three residues, mass measurements suggested extensive glycosylation. We propose that this extensive glycosylation renders these filaments soluble and provides the remarkable structural stability. We also show that the overall fold of the archaeal pilin is remarkably similar to that of archaeal flagellin, establishing common evolutionary origins.
learning native wisdom: what traditional cultures teach us about subsistence, sustainability, and spirituality
gary holthaus 2013
affluence without abundance: the disappearing world of the bushmen
james suzman 2017
the unthinkable: who survives when disaster strikes and why
amanda ripley 2008
the popular mechanics essential survival guide: the only book you need in any emergency
popular mechanics 2018
falter: has the human game begun to play itself out?
bill mckibben 2019
surviving survival: the art and science of resilience
laurence gonzales 2012
the art of resilience
ross edgley 2020
Link: 02014-41446361066658fe7281320494725947.html
Link: 01014-1123fcf36254a76e86e478500e9d8043.html