Tag Archives: mole

We’re getting a better idea of how moles turn into melanoma, and environment is key

New research is upending what we knew about the link between skin moles and melanoma.

Image via Pxhere.

Moles and melanomas are both types of skin tumors, and they originate from the same cells — the pigment-producing melanocytes. However, moles are harmless, and melanomas are a type of cancer that can easily become deadly if left untreated. The close relationship between them has been investigated in the past, in a bid to understand the emergence of melanomas.

New research at the Huntsman Cancer Institute (HCI) , the University of Utah, and the University of California San Francisco (UCSF) comes to throw a wrench into our current understanding of that link. According to the findings, our current “oncogene-induced senescence” model of the emergence of melanomas isn’t accurate. The research aligns with other recent findings on this topic, and propose a different mechanism for the emergence of skin cancer.

Environmentally-driven

“A number of studies have challenged this model in recent years,” says Judson-Torres. “These studies have provided excellent data to suggest that the oncogene-induced senescence model does not explain mole formation but what they have all lacked is an alternative explanation — which has remained elusive.”

Melanocytes are tasked with producing the pigments in our skin which protect us from harmful solar radiation. Changes (mutations) in one specific gene in the genome of melanocytes, known as BRAF gene mutations, are heavily associated with moles; such mutations are found in over 75% of skin moles. At the same time, BRAF gene mutations are encountered in 50% of melanoma cases.

Our working theory up to now — the oncogene-induced senescence– was that when melanocytes develop the BRAFV600E mutation, it blocks their ability to divide, which turns them into a mole. However, when other mutations develop alongside BRAFV600E, melanocytes can start dividing uncontrollably, thus developing into cancer.

The team investigated mole- and melanoma tissues donated by patients at the UCSF Dermatology clinic in San Francisco or the HCI Dermatology clinic in Salt Lake City. Their analysis revolved around two methods known as transcriptomic profiling and digital holographic cytometry. The first one allows them to determine molecular differences between the cells in moles and those in melanomas. The second one was used to track changes inside individual cells.

“We discovered a new molecular mechanism that explains how moles form, how melanomas form, and why moles sometimes become melanomas,” says Judson-Torres.

The team reports that melanocytes don’t need to have mutations besides BRAFV600E to morph into melanoma. What does play a part, however, are environmental factors, transmitted to the melanocytes through the skin cells around them. Depending on exactly what signals they’re getting from their environment, melanocytes express different genes, making them either stop dividing or divide uncontrollably.

“Origins of melanoma being dependent on environmental signals gives a new outlook in prevention and treatment,” says Judson-Torres. “It also plays a role in trying to combat melanoma by preventing and targeting genetic mutations. We might also be able to combat melanoma by changing the environment.”

The authors hope that their findings will help researchers get a better idea of the biomarkers that can predict the emergence of melanoma at earlier stages than possible today. Furthermore, the results here today can also pave the way to more effective topical medicine that can prevent melanoma, or delay its progress.

The paper “BRAFV600E induces reversible mitotic arrest in human melanocytes via microrna-mediated suppression of AURKB” has been published in the journal eLife.

Kilogram prototype replica.

The kilogram, ampere, mole, and Kelvin are changing to stay the same

The kilogram, ampere, Kelvin, and mole — fundamental units of measure in the International System of Units (SI) — are getting revamped.

Kilogram prototype replica.

A replica of the prototype of the kilogram at the Cité des Sciences et de l’Industrie, Paris, France.
Image credits Japs 88 / Wikimedia.

Representatives from 60 countries have voted in favor of redefining the SI last Friday at the General Conference on Weights and Measures in Versailles, France. The change aims to tie these units of measure to fundamental constants of the natural world, which improves reliability and ease of comparison.

Measures sans borders

“The SI redefinition is a landmark moment in scientific progress,” said Martin Milton, the Director of the International Bureau of Weights and Measures (BIPM). “Using the fundamental constants we observe in nature as a foundation for important concepts, such as mass and time, means that we have a stable foundation from which to advance our scientific understanding, develop new technologies and address some of society’s greatest challenges.”

The changes will remove the need for physical objects to define the units of measurement. They’re scheduled to come into effect on May 20th, 2019.

For more than a century, the kilogram has been tied to the mass of a particular physical object, a cylinder of platinum alloy called the International Prototype of the Kilogram (IPK) — which has been in the care of the BIPM in France. The organization is prepared to retire the object in favor of a mathematical definition based on the Planck constant, a fundamental constant in quantum physics.

The decision does make a lot of practical sense. Up to now, the only way to determine exactly how much mass an object has was to compare it to the IPK or identical copies; but such a process is difficult (you need to get your hands on an IPK copy) and potentially inaccurate (copies are imperfect and they can suffer physical or chemical alterations to its mass). The Planck constant, meanwhile, is readily available and exactly the same anywhere, anytime you need to use it.

New definitions have been penned for four of the seven base SI units: the kilogram, ampere, Kelvin and mole (and, by extension, and all units derived from them, such as the volt, ohm, and joule).

  • The kilogram — will be defined by the Planck constant (h).
  • The ampere — will be defined by the elementary electrical charge (e).
  • The Kelvin — will be defined by the Boltzmann constant (k).
  • The mole — will be defined by the Avogadro constant (NA).

“Today marks the culmination of decades of work by measurement scientists around the world, the significance of which is immense,” said Barry Inglis, Director of the International Committee for Weights and Measures.

“We will now no longer be bound by the limitations of objects in our measurement of the world, but have universality accessible units that can pave the way to even greater accuracy, and even accelerate scientific advancement.”

The actual ‘size’ of these units won’t change; a kilogram will still weigh one kilogram, for example. But the way we define them will be based in physical reality, not an object stowed away in a room somewhere. With the change, these four units will join the second, the meter, and the candela (base unit for luminosity) as physically-defined units of measurement — which will make them more stable and easier to use in precision applications.

Just like the 1967 redefinition of the second underpinned the GPS and internet, the committee explains, the new definitions will have wide-reaching impacts in science, technology, trade, health, and the environment, among many other sectors.

Naked mole-rats live extremely long lives and do not age, study finds

Biology’s ‘ugly duckling’ cannot cease to amaze us. Researchers have analyzed a large trove of data on historical naked mole-rat lifespan and discovered something truly amazing. Not only do the naked mole-rats live 5 times longer than a similar-sized mammal, but they also do not show any signs of aging whatsoever.

Credits: Flickr/Tim Evanson

Naked mole-rats’ superpowers

Mole-rats are astonishing creatures. What they lack in aesthetics they make up in superpowers: they’re immune to cancer, don’t feel pain, can switch from being cold-blooded to warm-blooded, can run backward as fast as forward, and can live in extremely low oxygen conditions, their brains being capable of surviving without oxygen for up to five hours. Also, their front teeth grow out in front of their mouths.

Their behavior is even weirder. The African mole-rat, scientifically known as Heterocephalus galber, exhibits eusociality. This means that mole-rats social life is more like an ant’s than that of a typical mammal. Only the queen and one to three chosen males are fertile and are in charge of reproduction. The other members of the colony (usually consisting of almost 300 mole-rats) are in charge of food gathering, burrow security, digging tunnels, tunnel maintenance, some of them even being nannies.

If the queen dies, any other unfertile female can be crowned. The regular working mole-rat is unfertile but can turn on the reproduction function if needed. Some biologists suggest that this could be one of the reasons mole-rats live such long lives, they believe that the tiny creatures are just waiting patiently to have offsprings.

Forever young

Lead researcher Rochelle Buffenstein has studied naked mole-rats for over 30 years and has collected a huge amount data on them, including lifespan. The comparative biologist, who works for Google’s anti-aging company Calico, was completely amazed by the results. She gathered data from over 3,000 specimens from her lab and discovered that the Gompertz-Makeham law, a mathematical equation that relates aging to mortality, doesn’t apply to mole-rats.

Basically, the law says that the risk of dying rises exponentially with age; in humans, for example, it doubles roughly every 8 years after the age of 30. This theory successfully applies to most animals, especially to mammals, but apparently not to our rodent super-heroes. A naked mole-rat’s daily risk of dying is a little more than one in 10,000, even after reaching sexual maturity at 6 months, and stays the same throughout their lives, sometimes even going down a little bit more. If this isn’t unfathomable, I truly don’t know what is.

“To me this is the most exciting data I’ve ever gotten,” says Buffenstein. “It goes against everything we know in terms of mammalian biology.”

Different studies have shown that the rodent possesses certain aging-protective qualities like very active DNA repair and high levels of chaperones, which are helper proteins that support other molecules in folding correctly. Buffenstein thinks that the almost-cute animal focusses more on keeping what it already has, rather than accumulate damage.

Adding the small number of predators, high resistance to cancer and friendly behavior to the equation, we might understand why these animals have such a small risk of dying prematurely.The oldest mole-rat in captivity is 35 years old. A mouse its size lives no longer than 4 years.

But anti-aging is something else, completely. For a change, the mole-rats’ blood vessels retain their elasticity, and the queens do not enter menopause and are still able to breed even at the age of thirty.

“Our research demonstrates that naked mole rats do not age in the same manner as other mammals, and in fact show little to no signs of ageing, and their risk of death does not increase even at 25 times past their time to reproductive maturity,” Buffenstein said.

“These findings reinforce our belief that naked mole rats are exceptional animals to study to further our understanding of the biological mechanisms of longevity.”

The paper was published Jan 24, 2018, in the journal eLIFE.

The eastern mole (Scalopus aquaticus) has its nostrils very closely separated, however it's been proven to be the first mammal to posses stereo smell. (c) Kenneth Catania, Wikipedia Commons

Moles smell in stereo to navigate for food

The eastern mole (Scalopus aquaticus) has its nostrils very closely separated, however it's been proven to be the first mammal to posses stereo smell. (c) Kenneth Catania, Wikipedia Commons

The eastern mole (Scalopus aquaticus) has its nostrils very closely separated, however it’s been proven to be the first mammal to posses stereo smell. (c) Kenneth Catania, Wikipedia Commons

Stereo sensing is a highly important skill that most animals possess that creates a directional perspective. Not all senses are stereo, however, in some animals. For instance, humans have stereo vision and hearing, however no stereo smell – the latter being a trait that not too many animals possess. The common mole has been found to display such an ability, after researchers at Vanderbilt University found the mammal relies on stereo smell to locate prey.

Few animals have so far been proven to have stereo smell, like some species of ants and sharks, although some that heavily rely on their sense of smell like pigs, mice or dogs might also possess this skill. The common mole (Scalopus aquaticus), which can be found wrecking havoc through backyard gardens anywhere from eastern United States and Canada to Mexico, is now the first mammal proven to smell in stereo.

“I came at this as a skeptic,” neuroscientist Kenneth Catania of Vanderbilt University was quoted as saying in a press release. “I thought the moles’ nostrils were too close together to effectively detect odor gradients. The fact that moles use stereo odor cues to locate food suggests other mammals that rely heavily on their sense of smell, like dogs and pigs, might also have this ability.”

The human auditory system is able to discriminate whether a sound comes from the right or from the left, if it is located behind, in front of, below or above the hearer. As a matter of fact, humans can distinguish sounds from two different sources, where the angle between the sources is only 3° – that’s very accurate. Similarly, with stereo smell one can detect different odor sources from each sources, with the brain being also wired to detect these differences. A sense of depth and orientation all based on smell is thus possible – for the common mole, at least.

Catania’s inspiration to study the common mole can be tracked back as far as ten years ago when he studied another mole, the star-nosed mole which uses a sort of tentacle-like tissue on its nose to sense food by touch.  He decided to test the common moles’ capability to find prey for comparison purposes.

“I expected the common mole, which is virtually blind and doesn’t have a very good sense of touch, to be a lot worse than the star-nosed mole. So I was quite surprised when they turned out to be very good at locating prey. At the time, I figured that they must be using their sense of smell, but I didn’t pursue the matter.”

[Also read] White smell: the neutral fragrance discovered by scientists

Since the two performed the same at finding food, despite sensing discrepancies between the two species, Catania naturally reasoned that the common mole’s sense of smell must be more sophisticated that previously thought. Catania presumed the mole must have stereo smell in order to guide itself and find mole, considering all its other senses didn’t provide navigation, so he put his idea to the test.

Where’s that smell coming from?

sniffHe made a radial arena with food wells spaced around a 180-degree circle with the entrance for the mole located at the center. Multiple tests were carried out with food (earthworms) placed randomly at different locations, while the arena was sealed at all time in order for Catania to see every time the mole sniffed by measuring the difference in air pressure. When the mole was introduced, Catania observed how the mammal first sniffed a bit back and forth around its location then immediately zeroed in on its target, the food source, on a direct path.

“It was amazing,” he said. ”They found the food in less than five seconds and went to the right food well almost every time. They have a hyper-sensitive sense of smell.”

To see whether indeed stereo smell aided navigation, Catania blocked each of mole’s two nostrils at a time and repeated the test. When the left nostril was blocked, the mole would still be able to locate food, but its path towards it was veered to left. The same, only opposite, happened when the right nostril was blocked.

“This is strikingly similar to a landmark study of hearing in barn owls performed in 1979 byEric Knudsen and Mark Konishi at the California Institute of Technology, who found that blocking one of the owl’s ears caused them to misjudge the location of a sound source,” Catania said.

In the ultimate test that finally proved moles indeed posses stereo smell Catania reversed the mole’s nostrils  after he inserted plastic tubes in both nostrils that were reversed. Thus, the right nostril was sniffing air on the animal’s left and the left nostril was sniffing air on the animal’s right. When their nostrils were crossed in this fashion, the animals searched back and forth and frequently could not find the food at all.

Findings were published in the journal Nature Communications. [source]

ZME readers, is the mole cool or what? Discuss in the comments section below.