Cells in the human body do not function in isolation. Living cells rely on communication with their environment—neighboring cells and the surrounding matrix—to activate a wide range of cellular functions, including reproduction of new cells, differentiation of stem cells into distinct cell types, cell adhesion, and migration of white blood cells to fight bodily infections. This cellular communication occurs on the molecular level and it is reciprocal: a cell receives cues from and also transmits function-activating cues to its neighbors.
The mechanics of this type of cellular interaction have been studied extensively: receptors extending through the cell membrane are activated when they form a bond to specific molecules. Now for the first time, University of Illinois biophysicists at the Center for the Physics of Living Cells and the Institute for Genomic Biology have measured the molecular force required to mechanically transmit function-regulating signals within a cell.
The new laboratory method, named the tension gauge tether (TGT) approach, developed by Taekjip Ha with postdoctoral researcher Xuefeng Wang, and reported in the May 24, 2013, issue of the journal Science, has made it possible to detect and measure the mechanics of the single-molecule interaction by which human cell receptors are activated. The researchers used integrin, a cell membrane receptor protein that is activated when it bonds to a ligand molecule.
In the TGT approach, Ha and Wang repurposed DNA strands, using them as tethers for ligand molecules, to test the tension required to activate cell adhesion through integrin. The integrin bonds to the tethered ligand, and adhesion is activated only if the DNA tether does not rupture (See video animation).
Taking advantage of the geometric characteristics of DNA’s double helix form, the researchers were able to tune the strands to rupture at discrete tension levels: by varying the attachment points along the DNA strands, the force required for rupture was either low (unzipping the helix), high (shearing the strands), or intermediary (combination of unzipping and shearing).
“If you went fishing and a fish broke your 30-lb fishing line but not the 40-lb one, you would know that its strength was in the range of 30–40 pounds,” explained Wang. “Here we applied the same strategy to measure the molecular tension applied by cells (the fish). Mammalian cells apply a force to activate cell membrane proteins called integrins which mediate cell adhesion. We immobilized ligand molecules (the bait) on a surface through molecular tethers (the fishing line) with defined tension tolerances, tunable from 10 pico Newton (pN) to 60 pN). After integrin-ligand binding, cells apply a force on the bonds, and we compare this force to the molecular tether strength by observing cell adhesion status.”
Since single-molecule interactions are difficult to monitor, the researchers observed the receptor-regulated cellular function, to gauge whether the integrin was activated. Ha and Wang discovered that integrin experiences a well-defined “quantum of force,” about 40 pico-Newton (pN), to activate cell’s adhesion to a surface.
“We observed that mammalian cells adhere on the culture surface with 43 pN tension tolerance of ligands, but not on 33 pN surface. Therefore we deduced that single molecular tension is around 40 pN on integrin cell-membrane receptors during cell adhesion,” Wang added.
“This is a very exciting result,” commented Ha, an Edward William and Jane Marr Gutgsell Endowed Professor at Illinois. “With the ability to define the single molecular forces required to make living cells behave as desired, we may be one step closer to a remedy for certain hard-to-cure diseases. We know that the behavior of cancer cells and stem cells can be controlled by how stiff or soft their environments are. Understanding and manipulating molecular conversation through defined forces has huge implications for the development of future medical interventions. We expect the TGT approach will have broad applications in laboratory studies of cell differentiation, cancer metastasis, as well as immunology and infectious disease.”
Planet Travel Posters Sets Mars & Venus by Ron Guyatt
Space tourism is still a long ways off, but it’s not hard to imagine that someday, tourists will visit the natural geological landmarks of other worlds much like they tour the Grand Canyon, Mount Everest or Ayers Rock. Each of these great tourist destinations needs a classic retro travel poster to entice visitors. Until the day people settle off world and make their own destinations many of these may be the places that people will want to travel too. I hope that these posters can inspire people to think beyond our world to the limitless possibilities of the Universe.
Posters Available at My Store
I want to go to there. And there. And there.
— June 23, 2013
Be sure to look out for the Moon these next few months as it approaches Perigee, because the full moons during these times will appear exceptionally large. The Moon will be at its Perigee, or closest approach, in July 23 and it will reach full moon only a few minutes after it passes this point in its orbit.
These ‘super moons’ not only appear larger because they are physically closer but, combined with a full moon, the mind can play tricks on you to think they are much larger. This phenomena is called the Moon Illusion. Try to catch these full moons as they rise/set because the illusion works when there is an object in the foreground, like a tree, building or mountains.
Fun fact: Cheetahs only attack prey that runs
jesus that is good to know.
Yup, that’s the point you just stay still and let it do whatever the fuck it wants that doesn’t involved you getting eaten.
REALLY FUN FACT for big cats cheetahs are fucking docile as shit
my grandfather ran a cheetah sanctuary in south africa and he’d just lie with them and sleep among them and they’d rub against him and chirp at him they’re big fucking babies
Another Fun Fact: Cheetahs are incredibly nervous animals. One of the (many) reason’s they’re going extinct is that cheetahs are so sensitive and nervous, some of them are literally too nervous to breed. Others will breed, but stress themselves out so much, they’ll lose their cubs.
So zoos with breeding programs had to figure out how to make cheetahs comfortable enough to first of all, get laid and secondly - not spazz themselves into miscarrying.
So what’d they do?
They gave the cheetah’s their very own Service Dogs!
The dogs make them feel safe, protected and secure!
AJHHHHFDDGHH SO PRECIOUS
this post just got so much better
THIS IS OFFICIALLY MY FAVOURITE POST
can i be a service human for a nervous cheetah
A tip from your favorite nurse
(that’d be me)
Always have eggs in your fridge
You just never know when someone will split their head open
Or cut their finger while cooking
And so on
See that membrane there?
While the blood is gushing - hold pressure and crack open an egg
Peel that there membrane off and put it on the wound (continue holding pressure)
The membrane will harden and keep the wound closed until you can get to the ER for stitches
If you even need them that is
Nature: 1, Band aids: 0
holy shit that’s really rad
Grass is the common name for the Gramineae family of plants. With more than 9,000 known species, this family is one of the largest on Earth.
Grass is extremely important to most people’s lives, whether they know it or not. For one thing, grass is a major food source all over the world. Rice, corn and oats come from grass plants, for example, and most livestock animals feed primarily on grasses. In some parts of the world, people use grass plants in construction (bamboo is a grass, for example), and wherever it grows, grass plays a vital role in curbing erosion. Grass is also used to make sugar, liquor, bread and plastics, among many other things.
Grasses have a very simple structure, and a very simple way of life. Keep reading to learn lots more, including how to get the stuff to actually grow in your lawn….
The chemical formulas of various substances used to mimic plant-based aromas and flavors.
Tastes like science.
This Week in Science - May 13 - 19, 2013:
- Magnetar at black hole here.
- Cloned human stem cells here.
- Cell calculators here.
- Music matched to color here.
- Scientists agreeing on climate change here.
- Remote-piloted plane here.
- Earth’s core here.
- Bright lunar explosion here.
- American asteroid sampling here.
- Hofstadter butterfly effect here.
- Electric shocks aid math skills here.
- Printable solar panels here.
Most of your body is younger than you are. The cells on the topmost layer of your skin are around two weeks old, and soon to die. Your oldest red blood cells are around four months old. Your liver’s cells will live for around 10 to 17 months old before being replaced. All across your organs, cells are being produced and destroyed. They have an expiry date.
Source: National Geographic
Photo reblogged from with 70,038 notes
Something to think about:
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