Lifeboat Foundation

Circa 2008

Cytokinesis partitions the cell by a cleavage furrow in animals but by a new cross wall in plants. How this new wall assembles at the molecular level and connects with the mother cell wall remains unclear. A lethal Arabidopsis embryogenesis mutant designated root-, shoot-, hypocotyl-defective (rsh) provides some clues: RSH encodes extensin AtEXT3, a structural glycoprotein located in the nascent cross wall or “cell plate” and also in mature cell walls. Here we report that electron micrographs of rsh mutant cells lacking RSH extensin correspond to a wall phenotype typified by incomplete cross wall assembly. Biochemical characterization of the purified RSH glycoprotein isolated from wild-type Arabidopsis cell cultures confirmed its identity as AtEXT3: a (hydroxy)proline-rich glyco protein comprising 11 identical amphiphilic peptide repeats with a 28-residue periodicity: SOOOOKKHYVYKSOOOOVKHYSOOOVYH (O = Hyp), each repeat containing a hydrophobic isodityrosine cross-link motif (YVY, underlined). Atomic force microscopy of RSH glycoprotein imaged its propensity for self-assembly into a dendritic scaffold. Extensin peroxidase catalyzed in vitro formation of insoluble RSH gels with concomitant tyrosine cross-linking, hence this likelihood in muro. We conclude that self-assembling amphiphiles of lysine-rich RSH extensin form positively charged scaffolds in the cell plate. These react with negatively charged pectin to create an extensin pectate coacervate that may template further orderly deposition of the new cross wall at cytokinesis.

Conflict of interest statement

Continue reading “Self-assembly of the plant cell wall requires an extensin scaffold” »

The idea is to make space livable for everyday folks rather than only specially-trained astronauts.

Physicists from Lancaster University have established why objects moving through superfluid helium-3 lack a speed limit in a continuation of earlier Lancaster research.

Helium-3 is a rare isotope of helium, in which one neutron is missing. It becomes superfluid at extremely low temperatures, enabling unusual properties such as a lack of friction for moving objects.

It was thought that the speed of objects moving through superfluid helium-3 was fundamentally limited to the critical Landau velocity, and that exceeding this speed limit would destroy the superfluid. Prior experiments in Lancaster have found that it is not a strict rule and objects can move at much greater speeds without destroying the fragile superfluid state.

PETERSON AIR FORCE BASE, Colo. (KRDO) – The North American Aerospace Defense Command says it is conducting air defense operations between September 20 and 23 in response to recent sightings of Russian aircraft.

Officials say they are doing the operations to “demonstrate NORAD’s air capability, readiness and will to defend the United States and Canada from competitors who continue to test our defenses.”

The organization says Russian aircraft were identified Friday evening within 50 nautical miles of Alaska’s Nunavik Island.

China has warned the US after it flew its ‘spy planes’ over the South China Sea several times electronically disguising as a civilian airplane.

“It is the old trick of the US military to use a transponder code to impersonate civil aircraft of other countries,” said Chinese Foreign Minister, Wang Wenbin, during his briefing.

Narendra Modi Second Indian Prime Minister To Win Ig Nobel Prize 2020

RS: The third world war is at our gate, and it will be about water, if we don’t do something about this crisis. These walks are to raise awareness—this year we covered 17 countries, and in nine of them there were displaced people. So many people in the Middle East and African countries are moving to places like Europe, in part because of water scarcity—after forced migration comes, tension, conflict, and terrorism. Where terrorism is active, there is usually a scarcity of water. Look at Syria—a long time ago, it had very good agriculture, but then Turkey built a dam that changed things. It’s a similar story with Libya. If we want a safe future, we need to start conserving water.

What role can regulation play in conservation? Do you think privatizing water is a good way to promote its efficient use?

RS: If we really think about legal changes, we have to first think about river rights, or the rights of nature, and only then about water rights for humans. This type of thinking doesn’t exist today but we need this kind of legal framework that assures that the land of the river is only for the river, that the flow of the river is kept clean, and that the river has greenery on both banks to prevent erosion and silting. Only with all these factors can we ensure that rivers are healthy and only then that we are healthy.

Resting on the tail of the Great Bear in the constellation of Ursa Major, lies NGC 5585, a spiral galaxy that is more than it appears.

The many stars, and dust and gas clouds that make up NGC 5585, shown here in this Hubble image, contribute only a small fraction of the total mass of the galaxy. As in many galaxies, this discrepancy can be explained by the abundant yet seemingly invisible presence of dark matter.

Continue reading “Dark Matter Surplus Captured by Hubble” »

Disc is left with warped and tilted rings.

The young triple star system GW Orionis appears to be surrounded by a ring of gas and dust that has torn away and become misaligned with the rest of the system’s circumstellar disc. That is the conclusion of an international team of astronomers led by Stefan Kraus at the University of Exeter – who combined observations with numerical simulations to identify disc structures that have been confined to theory until now.

Astronomers believe that most stars are born with one or more companions, which interact in complex ways with the disc of planet-forming gas and dust surrounding the stellar system. If this disc is misaligned with the orbital planes of the host stars, previous simulations have predicted that it will warp and tear under their gravitational torque, forming distinct rings in separate planes from the rest of the disc. So far, however, astronomers have yet to identify this tearing in their observations of misaligned discs.

Continue reading “Planet-forming disc is torn apart in triple star system” »

Outdoor diners are enjoying their meals in enclosed space bubbles set up at Upper West Side French restaurant Cafe du Soleil.

Here’s one way to enjoy outdoor dining well into October, as well as on rainy nights.

Another video shows diners enjoying live jazz in their bubbles on a recent rainy night.