Tissue engineering: How to build a heart : Nature News & Comment

Tissue engineering: How to build a heart : Nature News & Comment

A new exposé of Mother Teresa shows that she—and the Vatican—were even worse than we thought

A new exposé of Mother Teresa shows that she—and the Vatican—were even worse than we thought « Why Evolution Is True

Analytical Chemistry Techniques

Analytical Chemistry Techniques

Biochemists have used a combination of biochemistry & mass spec to “trap” new candidate substrates of the protease ClpXP to reveal how protein degradation is critical to cell cycle progression and bacterial development.
The bacterium Caulobacter crescentus (top image) was used for this work. It generates radically different cell types upon division. The ClpXP protease (bottom image) recognizes and destroys many protein substrates that allow Caulobacter to differentiate into these different cell types.

Read more on this work: http://bit.ly/10Cmd8u
Journal article: Identification of ClpP substrates in Caulobacter crescentus reveals a role for regulated proteolysis in bacterial development. Molecular Microbiology, 2013 DOI: 10.1111/mmi.12241
Image credit: Peter Chien, UMass Amherst

Stinging insects

Evolution

Stinging insects are equipped with a wide variety of ways to make us hurt, but which hurts the most? How painful is a yellowjacket's sting compared to a tarantula hawk's? A bee to a harvester ant?

Fortunately for us, we don't have to get the answers to these questions firsthand - an intrepid entomologist named Justin Schmidt has compiled a Pain Index to give us an idea. The Index rates the painfulness of the stings of Hymenopteran insects (an order that includes ants, wasps and bees) on a scale of 0 to 4. A rating of 0 describes a sting that cannot pierce the skin while a rating of 4 is awarded to the most painful. The quality of each sting is also described, usually with an analogy.

Though he has never intended to get stung, Schmidt has been stung by over 150 species in his career over six continents (Antarctica has no stinging insects). These painful experiences inspired him to categorize the stings and so the Pain Index was born. Though it is obviously subjective, being built on one man's experiences, we're perfectly happy to defer to his expertise!

Here's some descriptions from the list:

Sweat bee: 1.0. Light, ephemeral, almost fruity. A tiny spark has singed a single hair on your arm.

Bullhorn acacia ant: 1.8. A rare, piercing, elevated sort of pain. Someone has fired a staple into your cheek.

Yellowjacket: 2.0. Hot and smoky, almost irreverent. Imagine W. C. Fields extinguishing a cigar on your tongue.

Red Harvester ant: 3.0. Bold and unrelenting. Somebody is using a drill to excavate your ingrown toenail.

Tarantula Hawk (left): 4.0. Blinding, fierce, shockingly electric. A running hair drier has been dropped into your bubble bath.

Bullet ant: 4.0+. Pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a 3-inch rusty nail grinding into your heel.

Photo credit: Brian Van de Wetering.

For some more descriptions and explanations of how stings work:
http://io9.com/5912008/the-ten-most-painful-insect-stings-as-measured-by-science

http://io9.com/5836024/after-150-different-insect-stings-an-entomologist-becomes-a-connoisseur-of-pain

http://discovermagazine.com/2003/jun/featstung#.UdPaI_mZO8A

The sabre-toothed Thylacosmilus atrox

Evolution added a photo from July 5, 2013 to their timeline.

The sabre-toothed Thylacosmilus atrox might have had teeth the size of knives, but new research reveals its bite was "embarrassing".

To investigate Thylacosmilus's bite, researchers created biomechanical models of its skull and compared it to models of Smilodon and a leopard. The results showed that the jaw muscles of Thylacosmilus simply couldn't deliver a powerful bite - the team described its bite as "less powerful than a domestic cat" and its jaw muscles as "embarrassing". Previous research had demonstrated that Smilodon had a weak bite, but the bite of Thylacosmilus was even weaker.

However, the Thylacosmilus skull outperformed the others when it came to resisting forces from neck-driven bites. Thylacosmilus would have held down its prey with its thick forelimbs while its neck muscles drove the huge canines into the helpless animal (most likely into its prey's neck). Robust forearms were especially important to a sabre-tooth's attack - if the bite was not placed carefully or its prey twisted, the fragile canines could break.

These attack methods are almost identical to what previous studies concluded about how Smilodon attacked. Both predators have robust forearms, powerful neck muscles and large-but-fragile canines. However, Thylacosmilus was more specialised for the lifestyle - it had stronger neck muscles, weaker bite force and its teeth have roots almost in its braincase.

It's easy to assume Smilodon and Thylacosmilus were closely related, but the two are actually a stunning example of convergent evolution. While Smilodon was a true cat, Thylacosmilus was a marsupial and had a pouch. Scientists believe they were separated by around 125 million years of evolution, when the placental and marsupial lines diverged. Thylacosmilus also lived earlier, going extinct 3.5 million years ago, while Smilodon roamed North America until 10,000 years ago.

To read the paper: http://bit.ly/16BMHb8

Image credit: DiBgd.

http://news.nationalgeographic.com/news/2013/07/130702-sabertooth-cat-bite-prehistoric-science-animals/

http://www.livescience.com/37877-saber-toothed-predator-weak-bite.html

http://www.bbc.co.uk/news/science-environment-23126270

David Lehman on why Thomas Gray’s “Ode on a Distant Prospect of Eton College” is an overlooked poetic masterpiece. - Slate Magazine

David Lehman on why Thomas Gray’s “Ode on a Distant Prospect of Eton College” is an overlooked poetic masterpiece. - Slate Magazine

Lisa Randall’s Guide to the Galaxy | Science & Nature | Smithsonian Magazine

Lisa Randall’s Guide to the Galaxy | Science & Nature | Smithsonian Magazine