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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Why Some People Are Naturally Immune To HIV

Why Some People Are Naturally Immune To HIV:

With any virus, even devastating ones like Ebola and HIV, there are people who are exposed, often repeatedly, but somehow they never become infected or develop symptoms of disease. Though doctors have long wondered why, especially in the case of HIV, only today has a team of researchers found an explanation. Scientists at the University of Minnesota studying HIV-1 discovered some people have a specific variation of a gene, APOBEC3H, which produces an antiretroviral protein that inhibits the replication of HIV.

“We have seven APOBEC3 genes within the variants of human population,” Dr. Reuben S. Harris, a professor in the department of Biochemistry, Molecular Biology and Biophysics, explained to Medical Daily. Of these seven genes, “only APOBEC3H varies within the human population,” Harris added. APOBEC3H itself has seven variations, and if you broadly group these into those that make stable and those that make unstable proteins, Harris told Medical Daily, “What we found is those that are stable confer resistance to some forms of HIV.”

This important finding may pave the way to new treatments and drugs.

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Potential therapeutic target for Huntington’s disease

Potential therapeutic target for Huntington’s disease:

There is new hope in the fight against Huntington’s disease. Scientists at the Gladstone Institutes discovered that changing a specific part of the huntingtin protein prevented the loss of critical brain cells and protected against behavioral symptoms in a mouse model of the disease.

Huntington’s disease causes jerky, uncoordinated movements and a loss of control of motor function. It also results in deficits in learning and memory, as well as personality changes, such as dementia, depression, and aggression. Huntington’s is ultimately fatal, and there are no treatments to stop or slow its progression.

The disease is linked to a mutation in the Huntingtin gene, which causes a protein of the same name to fold up incorrectly like misshapen origami. Neurons cannot get rid of the misfolded protein, so it builds up in the brain, wreaking havoc in the cells.

In the new study, published in the Journal of Clinical Investigation, scientists in the laboratory of Steve Finkbeiner, MD, PhD, showed that modifying the huntingtin protein through a process called phosphorylation can actually make the protein less toxic and allows cells to eliminate it more easily. In fact, phosphorylating a specific spot on the protein called S421 protected a mouse model of Huntington’s from developing symptoms of the disease.

“I was shocked at the profound effect phosphorylation had on the Huntington’s model mice,” said first author Ian Kratter, MD, PhD, a former graduate student at Gladstone and the University of California, San Francisco (UCSF). “They showed few signs of the motor dysfunction, depression, or anxiety that are characteristic of the disease. In most of our tests, they were virtually indistinguishable from healthy mice.”

The mice were also protected against neuron death, particularly in the striatum, the movement and reward center of the brain that is first affected in Huntington’s disease. The scientists think that phosphorylation enables neurons to remove more of the harmful protein so it does not accumulate and damage the cell.

“Phosphorylation helps control how proteins fold and the systems in cells that clear proteins,” explained Finkbeiner, who is a senior investigator at Gladstone. “This is exciting, because a lot of the work we’ve done points to these protein removal pathways as being important not only for Huntington’s disease, but also for other neurodegenerative disorders. Understanding how phosphorylation links to these pathways could help treat several different brain diseases.”

The researchers are now exploring ways to mimic the effects of phosphorylation with a drug.

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Aphrodisiac virus makes plants super-attractive to bumblebees

Aphrodisiac virus makes plants super-attractive to bumblebees:

Going viral is a good thing. Viral infections can help some plants attract more pollinators and produce more seeds, essentially boosting – rather than hurting – their evolutionary fitness, a new study has found.

Plants are known to emit volatile chemicals that deter herbivores or attract pollinators or seed dispersers. Some viruses can change those volatiles to attract insects, such as aphids, that damage plants but help transmit the virus between them.

Now, a team of researchers lead by John Carr from the University of Cambridge has shown in greenhouse experiments that a cucumber mosaic virus can change the types and amounts of chemicals emitted by an infected tomato plant, so that it attracts more bumblebees to pollinate it. As a result, the plants in their experiments produced more seeds.

Without pollination, the virus affected the plants negatively, decreasing their seed production, compared with non-infected plants. But when bumblebees were present, it had the opposite effect.

When the researchers then modelled what would happen under natural conditions, they found that such viruses could indeed enhance plant attractiveness to pollinators enough to make up for loss of fitness due to infection.

This means that the benefits of the virus could outweigh the drawbacks, allowing genes for susceptibility to persist in plant populations.

“To my knowledge, this is the first evidence that virus infection can make plants more attractive to pollinators,” says Carr.

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One drug is ‘new hope’ for three killer infections

One drug is ‘new hope’ for three killer infections:

One drug can treat three deadly and neglected infections – Chagas disease, leishmaniasis and sleeping sickness – animal studies show.

It has been described as a “new hope” for tackling the parasitic infections which affect millions of people in the poorest parts of the world.

The discovery, reported in the journal Nature, was made by testing three million compounds.

The new drug is now entering safety tests before human trials.

The three diseases are all caused by similar parasites, leading scientists to believe one therapy might be useful against the trio.

  • Sleeping sickness is caused by the Trypanosoma brucei parasite, which is spread by the bite of the tsetse fly. The disease is officially known as Human African trypanosomiasis, but takes its more common name from the coma that results when the parasite penetrates the brain. It is found in sub-Saharan Africa.
  • Chagas disease – or America trypanosomiasis – is caused by the Trypansosoma cruzi parasite. It can cause the heart and digestive system to become enlarged, which can be deadly. The “kissing” or “assassin” bug spreads the parasite. Chagas mostly affects people in Latin America, but has now spread to other continents.
  • Leishmaniasis is caused by infection with Leishmania parasites and is spread by the bite of sandflies. It causes a wide range of symptoms depending on which part of the body is infected, ranging from anaemia and fever to the total destruction of the lining of the nose, mouth and throat. It is found in the Americas, Africa and Asia.

Combined, the three parasites infect 20 million people and kill 50,000 each year, the research team said.

While there are some drugs to treat the infections, they are expensive and toxic and often need to be given via an intravenous drip, making them impractical in poor regions.

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Celiacs rejoice! Bug-eating plant enzymes could hold key to gluten digestion

Celiacs rejoice! Bug-eating plant enzymes could hold key to gluten digestion:

Calgary scientists have made a breakthrough that could help celiac patients digest gluten with the help of an enzyme from bug-eating pitcher plants.

Pitcher plants are like “disposable stomachs” that are filled with an enzyme-rich liquid that helps them digest insect prey, explained lead researcher David Schriemer.

The professor at the University of Calgary says preliminary research shows the enzymes in these so-called monkey cups are “enormously potent” in breaking down gluten, and could work in a human stomach.

Schriemer said in a few years’ time, people with celiac disease could take a pill containing these enzymes, which would allow them to fully break down gluten.

“The idea here is that you would take it like Beano,” he said.

“We’ve taken it all the way through to animal trials at this point, and it seems to work.”

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Scientists have just uncovered a major difference between DNA and RNA

Scientists have just uncovered a major difference between DNA and RNA:

A new study has shown for the first time that RNA – the older molecular cousin of DNA – splits apart when it tries to incorporate change, while DNA can contort itself and change its shape to compensate for any chemical damage.

The research could finally explain why the blueprint of life is made from DNA and not RNA – and it could also prompt a rewrite of the textbooks.

“For something as fundamental as the double helix, it is amazing that we are discovering these basic properties so late in the game,” said lead researcher Hashim Al-Hashimi from the Duke University School of Medicine. “We need to continue to zoom in to obtain a deeper understanding regarding these basic molecules of life.”

Back in 1953, Watson and Crick first published their model of the DNA double helix, and predicted how the base pairs – A & T and G & C – fit together.

You’re probably pretty familiar with that formation by now – two strands of DNA are linked up by the bonding of the base pairs, forming ladder rungs that hold together the twisted ladder of DNA.

But researchers struggled to find evidence that the base pairs were bonding in the way that Watson and Crick had predicted – something they called Watson-Crick base pairs. Then in 1959, biochemist Karst Hoogsteen managed to take a picture of an A–T base pair, showing a slightly more skewed geometry, with one base rotated 180 degrees relative to the other.

Since then, researchers have observed both Watson-Crick and Hoogsteen base pairs in images of DNA.

But five years ago, Al-Hashimi and the Duke team found something that had never seen before: DNA base pairs constantly morphing back and forth between Watson-Crick and the Hoogsteen bonding configurations. This adds a whole other dimension and level of flexibility to DNA’s structure.

It turns out that DNA appears to be using Hoogsteen bonding when there’s a protein bond to a DNA site – or if there’s chemical damage to any of its bases – and once the damage is fixed or the protein is released, the DNA goes back to Watson-Crick bonds.

That discovery was a big deal in itself, but now the team has shown for the first time that RNA doesn’t have this ability, which could explain something that scientists have puzzled over for years: why DNA forms the blueprint for life, not RNA.

So, while DNA will absorb chemical damage and adapt to work around it, RNA becomes too stiff and falls apart, making DNA the better structure to pass genetic information down between the generations.

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Scientists have found a new way to stop skin damage and ageing from the Sun

Scientists have found a new way to stop skin damage and ageing from the Sun:

Traditional sunscreen works by reflecting harmful ultraviolet A (UVA) radiation away from your skin, but a new compound does something even better – it guards your skin cells from the effects of the sun from the inside out.

Offering protection inside the cell where the greatest damage from UVA occurs, this compound is said to offer “unprecedented protection” against skin cancer, and the effects of photoageing, such as sags, wrinkles, and sunspots.

Dubbed the mitoiron claw, the compound clings to the insides of cells, and prevents the kind of iron leakage that’s triggered by UVA exposure. If severe enough, this iron leakage can ultimately leads to cell destruction.

To understand why loose iron is such a problem, you need to understand how UVA affects cells. Radiation from the Sun unlocks free radicals – highly active oxygen molecules – in the skin, which then cause damage to DNA, cell membranes, and proteins.

At the same time, it also releases iron from the cell’s mitochondria, which depletes the cell’s energy supply and causes the cells to produce more free radicals. In other words, UVA causes cells to be killed off, and this can eventually lead to skin cancer.

It also causes skin to sag, wrinkle, and age, as you might have noticed if you spent a lot of time basking in the sunshine as a kid.

To combat this, researchers from the University of Bath and King’s College London in the UK developed the mitoiron claw, which is a type of chelator – a compound that binds to an iron atom. This allows it to target iron that’s loose in the mitochondria of the cell and prevent the release of extra free radicals.

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Tolerance of smoke may have given us an edge over Neanderthals

Tolerance of smoke may have given us an edge over Neanderthals:

Where there’s fire there’s often smoke – which might have been bad news for Neanderthals and other ancient hominins. Modern humans carry a genetic mutation that reduces our sensitivity to cancer-causing chemicals found in wood smoke. But Neanderthals and Denisovans apparently lacked the mutation.

Harnessing fire was one of the key events in hominin prehistory. Fire offered light, warmth, better protection from predators and the possibility of easier-to-digest cooked food. But smoke is something to be wary of. “Even today, smoke inhalation increases susceptibility to lung infections,” says Gary Perdew at Pennsylvania State University.

It might have been a significant problem during the Stone Age, given that hominins often lighted fires in caves or other enclosed areas. “If you were in a cave trying to cook, the amount of smoke you’d breathe in would be ridiculous,” says Perdew.

Our species, Homo sapiens, might have been particularly well suited to those conditions, though. Perdew and his colleagues looked at the genomes of three Neanderthals and a Denisovan, and compared them with genomes from living people and one member of our species who lived 45,000 years ago.

The researchers found that this ancient member of our species already carried a mutation not seen in either Neanderthals or Denisovans. It occurs in the AHR gene, which produces a receptor that helps regulate our response to carcinogenic polycyclic aromatic hydrocarbons often found in wood smoke.

The team inserted human and Neanderthal versions of the AHR gene into animal cells in the lab and examined how the cells responded when exposed to these carcinogens. The Neanderthal version proved to be far more likely to cause the production of enzymes that induce a toxic effect.

“We were surprised that the differences between the two were so large,” says Perdew. For some compounds there was a 1000-fold difference in the toxic response.

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Iron catalysts can modify amino acids, peptides to create new drug candidates

Iron catalysts can modify amino acids, peptides to create new drug candidates:

For medicinal chemists, making tweaks to peptide structures is key to developing new drug candidates. Now, researchers have demonstrated that two iron-containing small-molecule catalysts can help turn certain types of amino acids – the building blocks of peptides and proteins – into an array of potential new forms, even when part of a larger peptide, while preserving a crucial aspect of their chemistry: chirality, or “handedness.”

Led by Illinois chemistry professor M. Christina White, researchers from the University of Illinois at Urbana-Champaign in collaboration with researchers at Pfizer Global Research and Development detailed the new reactivity of the catalysts in the journal Nature.

“This allows us to take one amino acid structure and convert it into many different structures that represent different functionalities, which could ultimately lead to different biological and physical properties of the peptide,” White said. “It also expands the pool of unnatural chiral amino acids that are available to researchers to make new structures.”

A main advantage to the catalysts, which oxidize bonds between carbon and hydrogen, is that they preserve the amino acid’s sense of chirality. Chiral molecules can have more than one spatial arrangement of their atoms, or stereochemistry, sometimes known as “right-hand” and “left-hand” versions. Although they share the same chemical formula, molecules of opposite handedness can behave very differently in the body. For example, L-DOPA is a drug used to treat Parkinson’s disease, whereas its mirror version, D-DOPA, is biologically inactive.

“That’s why having things with defined stereochemistry can be very important for drug discovery,” White said. “It can be that a molecule of one handedness has fantastic physiological properties, but the same molecule with the opposite handedness could have very detrimental properties.”

Using the two iron catalysts, the researchers were able to take four chiral amino acids – proline, leucine, valine and norvaline – and diversify them into 21 different amino acid structures while preserving their handedness. The new structures can be used to create modified versions of existing peptides or to build entirely new structures.

Such oxidative amino acid modification is performed routinely in nature to make a variety of different peptides with different properties. Twenty common amino acids exist in nature, but are altered by carbon-hydrogen oxidation reactions to change their shape or add functional groups such as alcohols or carboxylic acids. These reactions are typically catalyzed by iron-containing enzymes. However, the enzymes are very difficult to work with in a laboratory setting, White said.

“These enzymes are also very specific. They are usually tailored to one amino acid or one peptide structure,” White said. “Two big advantages to the small-molecule catalysts we’ve developed are that they are very general – they can work on many different amino acid and peptide structures – and they are very easy to use. They can create great diversity initiated by one simple carbon-hydrogen oxidation reaction.”

Another major advantage the catalysts have is that, while they are general in what substrate they can oxidize, they are very specific about which carbon-hydrogen bonds they cut – so much so that they target a certain spot on amino acids like proline, leucine or valine even when they are part of a much larger peptide chain. For example, the researchers used the catalysts to transform a single proline-containing peptide chain into eight different peptides containing unnatural amino acids.

This is powerful because right now, if you want to make those eight different peptides, you would have to do eight different syntheses,” White said. “And before you could do that, you’d have to synthesize the individual unnatural amino acid components. With our method, you can build one peptide out of bulk chemicals and use one carbon-hydrogen oxidation reaction, coupled with a reaction to add a functional group, to produce eight new peptides all with retained handedness.”

One of the small-molecule iron catalysts, iron PDP, is available commercially from Sigma-Aldrich and Strem, and the researchers are in talks to make the second catalyst available as well.

White’s group is working on catalysts that can modify a wider range of amino acids, particularly those with electron-rich aromatic functionality, which compete with the carbon-hydrogen bonds for oxidation using the current catalyst.

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