Rattlesnakes silently shook their tails before evolving rattles

Rattlesnakes silently shook their tails before evolving rattles:

Shake, rattle and strike. It is possibly one of the most terrifying sounds in the animal kingdom, but how the rattlesnake evolved its chilling warning signal is a mystery. Now a study suggests the rattle evolved long after the tail-shaking behaviour.

The evolution of the rattle has baffled scientists because, unlike other complex physical traits like eyes or feathers, it has no obvious precursor or intermediate stage.

“There is no half-rattle,” says David Pfennig at the University of North Carolina at Chapel Hill.

One theory is that ancestral snakes shook their tails to warn off predators, and the noise-making rattle – which is made of a series of hollow, modified keratin scales – evolved later as a more effective signal that took advantage of the pre-existing behaviour. This may be why many rattle-less snakes also shake their tails.

To test the idea, Pfennig and his colleague prodded 56 species of venomous and non-venomous snakes with a fake rat on a stick and recorded their defensive tail shakes.

They found that the more closely related a snake was to the rattlesnake, the more similar its tail shake was in speed and duration.

“This suggests the defensive tail vibration came first, perhaps as a physiological response to stress, and that became a reliable cue to predators that the snake was about to strike,” says Pfennig. “When the rattle evolved, it became an even more effective signal.”

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Building blocks of memories seen in brains for the first time

Building blocks of memories seen in brains for the first time:

At last, we’ve seen what might be the primary building blocks of memories lighting up in the brains of mice.

We have cells in our brains – and so do rodents – that keep track of our location and the distances we’ve travelled. These neurons are also known to fire in sequence when a rat is resting, as if the animal is mentally retracing its path – a process that probably helps memories form, says Rosa Cossart at the Institut de Neurobiologie de la Méditerranée in Marseille, France.

But without a way of mapping the activity of a large number of these individual neurons, the pattern that these replaying neurons form in the brain has been unclear. Researchers have suspected for decades that the cells might fire together in small groups, but nobody could really look at them, says Cossart.

To get a look, Cossart and her team added a fluorescent protein to the neurons of four mice. This protein fluoresces the most when calcium ions flood into a cell – a sign that a neuron is actively firing. The team used this fluorescence to map neuron activity much more widely than previous techniques, using implanted electrodes, have been able to do.

Observing the activity of more than 1000 neurons per mouse, the team watched what happened when mice walked on a treadmill or stood still.

As expected, when the mice were running, the neurons that trace how far the animal has travelled fired in a sequential pattern, keeping track.

These same cells also lit up while the mice were resting, but in a strange pattern. As they reflected on their memories, the neurons fired in the same sequence as they had when the animals were running, but much faster. And rather than firing in turn individually, they fired together in sequential blocks that corresponded to particular fragments of a mouse’s run.

“We’ve been able to image the individual building-blocks of memory,” Cossart says, each one reflecting a chunk of the original episode that the mouse experienced.

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Ultrasound has been used to ‘jumpstart’ a coma patient’s brain for the first time

Ultrasound has been used to ‘jumpstart’ a coma patient’s brain for the first time:

sciencealert:

Researchers in the US have pioneered the use of ultrasound to successfully ‘restart’ brain activity in a coma patient for the first time.

It’s too early to say if the technique will be safe and effective every time, but it could give doctors a non-invasive option for treating those who would otherwise be stuck in a vegetative state.

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2nd Tool-Using Crow Species Found

2nd Tool-Using Crow Species Found:

The critically endangered Hawaiian crow can use sticks to deftly fish for food that is out of reach, according to a new study. The discovery means there are now two known tool-using species of crows.

“The Hawaiian crows are incredibly good at using tools,” said lead study author Christian Rutz, a biologist at the University of St Andrews in the United Kingdom. “What we see is similar to the really skilled tool handling in New Caledonian crows.”

Until now, New Caledonian crows had been the only corvid (a group that includes crows, ravens and rooks) species known to use tools. These birds have become famous for their expert ability to fashion hooks from sticks to snag larvae and insects from crevices in logs or branches. [Creative Creatures: 10 Animals That Use Tools]

Rutz had studied the New Caledonian crow for more than a decade. In one paper, published in the journal Nature in 2012, he and his colleagues showed how the birds have physical characteristics that enable their tool control: straight bills and very large eyes with a large field of binocular vision.

Rutz told Live Science he wanted to look for other birds that shared these features, thinking those traits could be preadaptations for tool use. That led him to the Hawaiian crow, also called the ‘alalā (pronounced AH-la-la).

The one problem was that the birds had been declared extinct in the wild by 2004. (Just 131 are alive today.) So Rutz got in touch with San Diego Zoo Global, a nonprofit organization that operates the San Diego Zoo and was breeding the ‘alalā in captivity in Hawaii. People at the captive breeding facility told him they had sometimes seen the birds use sticks but didn’t think much of it.

“I immediately booked my flight to Hawaii,” Rutz said.

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The Forgotten Woman Who Made Microbiology PossibleLab work can…

The Forgotten Woman Who Made Microbiology Possible

Lab work can be a lot like cooking. You have to follow directions to measure, mix, and heat different chemicals to the right temperature to get the desired result. For some experiments, the desired result is actually something that can be eaten by a range of different organisms. In microbiology labs, feeding bacteria is a major preoccupation, and preparing the proper growth medium in a lab’s “kitchen” is often the first step of any experiment. Petri dishes are filled with a sort of savory Jell-O, a nutrient-filled semi-solid matrix that creates a cozy home for bacteria to grow. Without the solid-yet-moist surface of the gel where the bacteria can cling to and reproduce, there’s little hope of separating a bacterial cell from its environment in order to study it.

In the earliest days of microbiology, scientists were stumped about how to isolate bacteria. That is, until the family cook—a woman named Angelina—changed everything by bringing her culinary insight into the lab. Before Angelina, the work of classifying different bacteria seemed hopelessly complex. Unable to differentiate them, Linnaeus classified all bacteria in the order Chaos in 1763. (Today, Chaos is a genus of giant amoebae.) In the 1800s, scientists studying the spots of fungus growing on moldy bread and meat began to realize that each spot was an individual species of microorganism, which could be transferred to a fresh piece of food and grown in isolation. Inspired by these early food-based studies, Robert Kochused thin slices of potatoes as naturally occurring “Petri dishes” when he began his studies of bacterial pathogens.

New techniques to isolate, grow, and study the behavior of individual species of microorganisms were developed in Koch’s lab in the last decades of the 19th century. In a 1939 article, Arthur Hitchens and Morris Leikind described the history of these crucial microbiological techniques and the development of the solid medium still used in labs today. They begin by writing that Robert Koch’s “genius lay in his ability to bring order out of chaos. Starting as it were with a box of miscellaneous beads, varying in size and shape, each bead a scientific fact, he found a thread on which the beads could be strung to form a perfect necklace.” But they continue to highlight not only the genius “bead stringers” but also the numerous and talented “bead collectors” who help to build the tools and collect the data that the bead stringers use. For Koch’s legendary discoveries of the bacteria that cause diseases like tuberculosis and cholera to be possible, he needed new techniques to effectively isolate bacteria beyond carefully sliced potatoes. He needed the tools that were developed by his less-celebrated laboratory assistants, like Julius Richard Petri’s dishes and Walther Hesse’s solid growth medium.

But behind the talented laboratory technicians that supported Robert Koch’s genius was an even more unsung heroine of microbiology. It was Walther Hesse’s wife (who was often an assistant and scientific illustrator for the lab) Angelina Fanny Hesse who made the isolation of bacteria possible. In the early 1880’s, Walther was struggling to find the right sort of gel for Petri’s dishes. He was experimenting with using gelatin to congeal the nutrient broth that the bacteria ate, but bacteria also liked to eat the proteins that congealed the gelatin, chewing through the gel and ruining the experiments. Gelatin also had another major drawback: it would soften and begin to melt at the incubation temperatures required for growing the bacteria.

Angelina, who cooked both the family’s meals and the beef stock that the bacteria ate in her kitchen, suggested that Walther use agar-agar, which is more heat-stable than gelatin and used to make soups, desserts, and jellies, particularly in Asia. (She had learned about it from Dutch friends who had lived in Indonesia, which was a colony of the Netherlands at the time.) Agar is a sugar polymer derived from algae that most bacteria can’t digest. Once it’s boiled and cooled, it forms a tough matrix that stays solid at much higher temperatures than gelatin.

With agar, many of the technical problems hindering Hesse’s—and therefore Koch’s—experimental progress were solved. Koch briefly mentioned the development (though he fails to mention either Walther or Angelina) in his 1882 paper announcing the identification of the bacteria that causes tuberculosis: “The tubercule bacilli can also be cultivated on other media…they grow, for example, on a gelatinous mass which was prepared with agar-agar, which remains solid at blood temperature, and which has received a supplement of meat broth and peptone.”

Angelina Hesse’s creative insight was thus written out of history with the ever-present passive voice of the scientific literature. Even today, the Wikipedia article about Robert Koch masks Angelina’s contribution to microbiological history, simply stating that Koch “began to utilize agar to grow and isolate pure cultures.” In the late 19th century, the use of agar to isolate bacteria was initially referred to as “Koch’s plate technique,” but since the early 1900s only Petri’s name remains in common use. In their article, Hitchens and Leikind suggested (seventy five years ago) that “plain agar” be referred to as “Frau Hesse’s medium” to acknowledge her forgotten “service to science and to humanity.” Perhaps it’s finally time that we remember Frau Hesse and celebrate all the ignored “bead collectors” working in the laboratories and kitchens that make science possible.

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Scientists just figured out why poison ivy makes us itch so much

Scientists just figured out why poison ivy makes us itch so much:

An international team of researchers has finally decoded the science behind a plant responsible for no small degree of human misery: poison ivy.

For the first time, we now know why poison ivy leaves – the bane of campers, hikers, and overly curious kids alike – make us itch, and the answer lies in a key molecule called CD1a, which scientists have long known about but didn’t fully understand until now.

“For over 35 years we have known CD1a is abundant in the skin,” says researcher Jerome Le Nours from Monash University in Australia. “Its role in inflammatory skin disorders has been difficult to investigate and until now has been really unclear.”

One of the reasons for that lack of clarity has been that many experiments on skin disorders involve animal testing – specifically lab mice. And mice don’t produce CD1a, effectively creating a kind of ‘blind spot’ in the studies up to this point.

To get around this and examine whether CD1a might play a part in how human skin reacts when we brush up against poison ivy (Toxicodendron radicans) and similar rash-inducing plants, the researchers genetically engineered mice that did produce the molecule.

In doing so, the team found that CD1a – a protein that plays an important role in our immune systems – triggers a skin-based allergic reaction when we come into contact with urushiol, the allergen that functions as the active ingredient in plants like poison ivy, poison oak, and poison sumac.

When urushiol interacts with skin cells called Langerhans cells, the CD1a proteins (which are expressed by Langerhans cells) activate the immune system’s T cells. In turn, the T cells produce two proteins – interleukin 17 and interleukin 22 – which cause inflammation and itchiness.

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invertophiles: Pseudoscorpions…like scorpions, only not! When…

invertophiles:

Pseudoscorpions…like scorpions, only not!

When you discover pseudoscorpions I expect you to be charmed; if not, then I surely won’t forgive you.

Pseudoscorpions, as their name suggests, are very distantly related to scorpions – at least they are in the same class (Arachnida), along with spiders, harvestmen, mites and a few other slightly unusual odds and ends. In contrast to scorpions they obviously lack a tail and sting and are quite tiny, mostly millimetres long and cryptic (you need to be looking closely).

Here in Australia (where these pictures were all taken) there are around 150 described species in about 21 different families. Experts estimate there might be 700 species, meaning most remain undescribed. They are commonly found in leaf litter or under bark, but can also be found in ants nests and caves.

Remarkably, these creatures have been around since the middle Devonian (380 million years ago) and are considered one of the first organisms to leave the oceans for dry land.

Good on ya pseudoscorpions!

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When…

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