With-science

Estamos viviendo el siglo de la Biología evolucionista.
Valparaíso, Chile 2014

Valparaíso, Chile 2014

Valparaíso, Chile

Valparaíso, Chile

Valparaiso, Chile

Valparaiso, Chile

neuromorphogenesis:

Beyond Salty and Sweet: A Budding Club of Tastes

Sweet, salty, sour and bitter — every schoolchild knows these are the building blocks of taste. Our delight in every scrumptious bonbon, every sizzling hot dog, derives in part from the tongue’s ability to recognize and signal just four types of taste.

But are there really just four? Over the last decade, research challenging the notion has been piling up. Today, savory, also called umami, is widely recognized as a basic taste, the fifth. And now other candidates, perhaps as many as 10 or 20, are jockeying for entry into this exclusive club.

“What started off as a challenge to the pantheon of basic tastes has now opened up, so that the whole question is whether taste is even limited to a very small number of primaries,” said Richard D. Mattes, a professor of nutrition science at Purdue University.

Taste plays an intrinsic role as a chemical-sensing system for helping us find what is nutritious (stimulatory) and as a defense against what is poison (aversive). When we put food in our mouths, chemicals slip over taste buds planted into the tongue and palate. As they respond, we are thrilled or repulsed by what we’re eating.

But the body’s reaction may not always be a conscious one. In the late 1980s, in a windowless laboratory at Brooklyn College, the psychologist Anthony Sclafani was investigating the attractive power of sweets. His lab rats loved Polycose, a maltodextrin powder, even preferring it to sugar.

That was puzzling for two reasons: Maltodextrin is rarely found in plants that rats might feed on naturally, and when human subjects tried it, the stuff had no obvious taste.

More than a decade later, a team of exercise scientists discovered that maltodextrin improved athletic performance — even when the tasteless additive was swished around in the mouth and spit back out. Our tongues report nothing; our brains, it seems, sense the incoming energy.

“Maybe people have a taste for Polycose,” Dr. Sclafani said. “They just don’t recognize it consciously, which is quite an intriguing possibility.”

Dr. Sclafani and others are finding evidence that taste receptors on the tongue are also present throughout the intestine, perhaps serving as a kind of unconscious guide to our behavior. These receptors influence the release of hormones that help regulate food intake, and may offer new targets for diabetes treatments, Dr. Sclafani said.

Many tastes are consciously recognized, however, and they are distinguished by having dedicated sets of receptor cells. Fifteen years ago, molecular biologists began figuring out which of these cells in the mouth elicit bitter and sweet tastes.

By “knocking out” the genes that encode for sweet receptors, they produced mice that appeared less likely to lap from sweet-tasting bottles. Eventually, the putative receptors for salty and sour also were identified.

In 2002, though, as taste receptors were identified, the evidence largely confirmed the existence of one that scientist had been arguing about for years: savory.

Umami is subtle, but it is generally described as the rich, meaty taste associated with chicken broth, cured meats, fish, cheeses, mushrooms, cooked tomatoes and seaweed. Some experts believe it may have evolved as an imperfect surrogate for detecting protein.

Since then, researchers have proposed new receptor cells on the tongue for detecting calcium, water and carbonation. The growing list of putative tastes now includes soapiness, lysine, electric, alkaline, hydroxide and metallic.

“The taste field has been absolutely revolutionized,” said Michael Tordoff, a biologist at the Monell Chemical Senses Center. “We’ve made more progress in the last 15 years than in the previous 100.”

One candidate for the next basic taste appears to have emerged as the front-runner: fattiness. The idea has been around for a while, and many scientists thought it was not a specific taste, more like a texture or an aroma.

But researchers recently identified two taste receptors for unsaturated fats on the tongue. And fat evokes a physiological response, Dr. Mattes has found that blood levels of fat rise when we put dietary fat in our mouths, even without swallowing or digesting it.

Hours after a meal, the taste of fatty acids alone can elevate triglyceride levels, even when the nose is plugged. But fat, like umami, does not have a clear, perceptible sensation, and it is hard to distinguish a texture from a taste.

Dr. Mattes says that fat may have a texture that we like (rich and gooey) and a taste that we don’t (rancid).

If so, the taste may serve as part of our sensory alert system. When food spoils, he notes, it often contains high levels of fatty acids, and the taste of them may be “a warning signal.”

Although there is still no consensus beyond sweet, salty, sour, bitter and savory, the research makes clear there is more to taste than a handful of discrete sensations on the tongue. Before long, scientists may have to give up altogether on the idea that there are just a few basic tastes.

“If you’re talking three, four, five, six, you can still call it a pretty exclusive club,” Dr. Mattes said. “If you start getting beyond that, is the concept really useful?”

antikythera-astronomy:

Yo dogs. Wanna know something important and scary?

One of the many essential things needed to keep Earth habitable for us is an outer core inside Earth that is both liquid, electrically conductive and rapidly rotating. What this does is it basically turns Earth into a giant magnet. As shown in the third picture, an electromagnetic field extends outward from the Earth. The particles that get charged are shot up (or down) to the North (or South) Pole and when they get there they have nowhere to go resulting in an unbalanced negative charge. Since all charges want to be neutral they emit their charge as photons. This is what the Northern Lights are.

What’s so damn important about this magnetic field? It protects us from the dangerous radiation from space which would turn you into a giant tumor in no time. It also protects our ozone layer from being stripped away by the Sun. without which we would lose all our oxygen and heat. And die.

Now, what’s scary? The conductive, liquid hot stuff in the Earth’s core is slowly cooling and slowing down. If you want an idea of what a body looks like once the hot core cools and stops moving look at pictures of the Moon and Mars. That’s Earth’s destiny. Happy Weekend! :)

P.S. As the spinning slows and the liquid cools, the Aurora Borealis will slowly disappear.

(via alvarson)

biocanvas:

Human cortical neural stem cells
Cortical neurons are located in the cerebral cortex of the brain, a region responsible for memory, thought, language, and consciousness. Neural stem cells are “immature” cells committed to become neurons and helper cells of the brain. Neurons are the liaison between our brain and the world. When we eat a lemon, neurons connected to our taste buds tell the brain that it’s sour. Messages from the brain can also be sent elsewhere, as when neurons command muscles to contract while lifting a heavy object.
Image by Kimmy Lorrain, BrainCells, Inc.

biocanvas:

Human cortical neural stem cells

Cortical neurons are located in the cerebral cortex of the brain, a region responsible for memory, thought, language, and consciousness. Neural stem cells are “immature” cells committed to become neurons and helper cells of the brain. Neurons are the liaison between our brain and the world. When we eat a lemon, neurons connected to our taste buds tell the brain that it’s sour. Messages from the brain can also be sent elsewhere, as when neurons command muscles to contract while lifting a heavy object.

Image by Kimmy Lorrain, BrainCells, Inc.

(Source: promo.gelifesciences.com, via science-junkie)

ohyeahdevelopmentalbiology:

scienceyoucanlove:

CALICO DOG MAY BE A CHIMERA

A photograph of a dog at a veterinary hospital has gone viral this week because of the animal’s unusual but beautiful markings. The Labrador Retriever, Bull, has a coat colored like that of a calico cat. He is a patient at Texas A&M Veterinary Medical Teaching Hospital, according to MSN Now.

Because of Bull’s unique coat, he is suspected of being a chimera, a single animal that genetically is two animals, i.e., an individual that is its own twin. Bull, then, appears to be a chimera that is both black Lab and yellow Lab.

We saw this phenomenon last summer when a "two-faced" calico chimera cat named Venus caught the Internet’s attention. Bull has emerged as Venus’ canine counterpart, albeit without the same dead-even color split down the middle of his face.

Whether Bull is a chimera hasn’t been confirmed medically yet, but we’ll watch the veterinary hospital’s Facebook page to see if they post any further information and, hopefully, more photos of this interesting dog.

source


What is a chimera?

A chimera is typically formed from four parent cells (either two fertilized eggs, or two early embryos that have fused together).When the organism forms, the cells that had already begun to develop in the separate embryos keep their original phenotypes and appearances — resulting in a two-faced cat like Venus. (see second picture)

It can happen to humans too. In 1953 a human chimera was reported in the British Medical Journal. A woman was found to have blood containing two different blood types that apparently resulted from cells from her twin brother living in her body. Other such instances have been reported in the decade since.

source