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SINGULAR EVENT. "So, why did prokaryotes not evolve into eukaryotes more than once? The reason is that it is impossible to generate this amount of energy in a single cell unless that cell has a powerhouse of energy production with a large membrane surface — that is, a mitochondrion." https://lnkd.in/dz-st9e View in LinkedIn

FRAGMENT FROM NATURE continues from last weekend with a consideration of the biology of spider webs, how they arose, and how and why they function as they do. It is a lovely story of inventiveness at many scales: the molecular design of the material with sliding hydrogen bonds giving it toughness; the various positioning of the webs giving rise to substrate freedom; and the web geometry that exploits efficiency of an expensive material with high functionality for a powerful prey. View in LinkedIn

HYDROGEN POWERED train in Germany. https://lnkd.in/dXv_6qC View in LinkedIn

FALSE PREMISE 4. "Fourth, and perhaps most importantly, it is difficult and may be impossible to eliminate eukaryocentric bias from the measures by which eukaryotes as a whole are judged to have achieved greater success than prokaryotes as a whole." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

FALSE PREMISE 3. "Third, identifying which of several complex cellular features confer on eukaryotes a putative richer evolutionary potential remains an area of speculation: various keys to success have been proposed and rejected over the five-decade history of research in this area." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

FALSE PREMISE 2. "Second, eukaryogenesis confronts evolutionary theory in ways not different from other evolutionary transitions in individuality; parallel systems can be found at several hierarchical levels." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

FALSE PREMISE 1. "First, the criteria by which we judge eukaryogenesis to have required a genuinely unlikely series of events 2 billion years in the making are being eroded by discoveries that fill in the gaps of the prokaryote:eukaryote “discontinuity.”." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

MASSIVE EXTENSIBILITY. "While untested, the high extensibility of viscid silk (up to 1000%) may add an additional safety factor preventing breakage, as a struggling insect is unlikely to extend the silk this far." https://lnkd.in/dqTjK77 View in LinkedIn

FUNCTION OF STICKINESS. "Stickiness of viscid silk is ultimately constrained by the tensile strength of its axial fibres. Stickiness increases linearly with tensile strength, but is always less than the force required to break the axial fibres. This safety factor allows threads to repeatedly detach and reattach to prey, rather than breaking, as prey struggle to escape the web." https://lnkd.in/dqTjK77 View in LinkedIn

DUPONT once had an advert in CE&N showing a suspension bridge made of spider silk and a text claiming that a single cable of silk could hold back a jet. The US army dreamed of making lightweight bulletproof alternatives to Kevlar. At an earlier point in my own life I was engaged in an effort to clone the spider silk gene. Recently, recombinant and functional spider silk has been reported, along with heterologous host systems, but scale-up remains a considerable challenge. https://lnkd.in/dmvrhKR View in LinkedIn