Tag Archives: Mechanisms

Research reveals that a multitude of plants, fungi, protists, bacteria, and viruses possess toxin delivery mechanisms.

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These toxin delivery systems are completely similar and often rival the complexity of the venom delivery systems found in animals such as venom snakes, scorpions, and spiders.

Four representative plant species introducing the poison delivery system: (a) Many ant plants share ants that provide homes and food. (b) Horstria, a parasitic plant that attacks other plants. (c) Stingy trichomes of stinging plants. (d) Raffide penetrates the oral membrane of an animal browsing a plant. Image credit: Hayes et al. , doi: 10.3390/toxin 17030099.

Toxologists and other biologists have studied toxic organisms and their secretions for centuries.

Their interest is largely due to the frequently and severe consequences of human exposure.

Humans also take advantage of the potential of toxins to explore the treatment of human illnesses and illnesses.

In doing so, scientists have leveraged countless natural experiments involving interactions between toxins and target cells and tissues.

The classification of biological toxins, in particular the distinction between venom and venom, is characterized by a colorful and sometimes controversial history.

Nevertheless, with the views of consensus and the introduction of the third phase, toxic biological secretions can be divided into three groups based on their mode of delivery to other organisms.

These include poisons that are transmitted passively without a delivery mechanism (intake, inhalation, or absorption of the entire surface). Toxicity was fed to the body surface without any associated wounds (e.g., spitting, spraying, or smearing). Poison (e.g., sting, biting) carried to internal tissues through the formation of wounds.

The organisms that possess these toxins are called toxic, toxins, and/or toxic, respectively.

These distinctions provide a meaningful framework for studying the evolution of these toxins, including biochemical structures. Related structures for synthesis, storage and application. And their functional role.

Discourses on poison and poisonous animals focus exclusively on animals.

The use of venom has evolved independently in at least 104 strains within at least eight animal phylums, which emphasizes the pronounced adaptability of the trait.

But do poison distribution systems exist in other entities?

“Our findings show that we rely on poisons to solve problems such as predation, defense, and competition.

“The venomous animals have long been trying to understand the fatal secretions and the properties associated with their use, but have long fascinated biologists who have also contributed to many life-saving treatments.”

“To date, our understanding of venoms, poison delivery systems, and poisonous organisms is entirely based on animals. This represents only a small fraction of organisms that can search for meaningful tools and treatments.”

According to the study, plants inject toxins into animals through spines, thorns and stinging hairs, some of which exist with stinging ants by providing living space and food in exchange for protection.

Even bacteria and viruses have evolved mechanisms such as secretory and contractile injection systems to introduce toxins to the target through host cells and wounds.

“I have a long history of studying venom in rattlesnakes, and I began exploring the broader definition of venom over a decade ago, teaching special courses on the biology of venom,” Professor Hayes said.

“My team and I were working on a paper to define what Venom really is, so we came across non-animal examples and decided to dig deeper to identify many of the possible overlooked examples.”

This research paves the way for new discoveries, and the authors hope that experts and scientists will encourage collaboration across disciplines and explore further how Venom has evolved across diverse organisms.

“We only hurt the surface in understanding evolutionary pathways of venom dissemination, including gene duplication, co-configuration of existing genes, and natural selection,” concluded Professor Hayes.

study Published in the journal toxin.

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William K. Hayes et al. 2025. After all, it’s a small world. It is a prominent yet overlooked diversity of poisonous organisms with candidates for plants, fungi, protists, bacteria and viruses. toxin 17(3):99; doi:10.3390/toxin 17030099

Source: www.sci.news

Recent studies uncover the mechanisms by which Deinococcus bacteria can survive high levels of radiation

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called radiation-resistant bacteria Deinococcus radiodurans It can withstand radiation doses thousands of times higher than what would kill a human. The secret behind this resistance is the existence of a collection of simple metabolites that combine with manganese to form a powerful antioxidant. Now, Northwestern University professor Brian Hoffman and his colleagues have discovered how this antioxidant works.

Deinococcus radiodurans. Image credit: USU/Michael Daly.

First discovered in 1956, Deinococcus radiodurans It is one of the most radiation-resistant organisms known.

It was isolated in an experiment aimed at determining whether high doses of gamma rays could be used to sterilize canned food.

In a new study, Professor Hoffman and co-authors characterized a synthetic designer antioxidant called MDP. Deinococcus radiodurans'Resilience.

They show that the components of MDP, manganese ions, phosphates, and small peptides, form a ternary complex that is a much more powerful protector from radiation damage than when manganese is combined with other individual components alone. I discovered that.

This discovery could ultimately lead to new synthetic antioxidants specifically tailored to human needs.

Applications include protecting astronauts from intense space radiation during deep space missions, preparing for radiation emergencies, and producing radiation-inactivated vaccines.

“This ternary complex is MDP's excellent shield against the effects of radiation,” said Professor Hoffman.

“It has long been known that manganese ions and phosphates together make a powerful antioxidant, but now we discover and understand the 'magical' potency brought about by the addition of a third ingredient. That's a breakthrough.”

“This study provided the key to understanding why this combination is such a powerful and promising radioprotector.”

In a previous study, researchers found that: Deinococcus radiodurans It can withstand 25,000 Grays (or units of X-rays and gamma rays).

But in a 2022 study, Professor Hoffmann and his team found that this bacterium, when dried and frozen, can withstand 140,000 Gy of radiation, 28,000 times the dose that would kill humans. did.

Therefore, if there are dormant frozen microbes buried on Mars, they may have survived the onslaught of galactic cosmic radiation and solar protons to this day.

In an effort to understand radioresistance in microorganisms, researchers investigated a designer decapeptide called DP1.

When combined with phosphate and manganese, DP1 forms the free radical scavenger MDP, which protects cells and proteins from radiation damage.

Professor Michael Daly, from Uniformed Services University, said: “This new understanding of MDP could lead to the development of even more powerful manganese-based antioxidants with applications in areas such as medicine, industry, defense and space exploration. Yes,” he said.

of result will appear in Proceedings of the National Academy of Sciences.

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Hao Yang others. 2024. A ternary complex of Mn2+, synthetic decapeptide DP1 (DEHGTAVMLK), and orthophosphate is an excellent antioxidant. PNAS 121 (51): e2417389121;doi: 10.1073/pnas.2417389121

Source: www.sci.news

Scientists explore the mechanisms of DNA methylation in plants

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DNA methylation is one of several epigenetic mechanisms important for controlling gene expression in eukaryotes.

Arabidopsis. Image credit: Carl Davies, CSIRO/CC BY 3.0.

DNA methylation is a normal biological process in living cells in which small chemical groups called methyl groups are added to DNA.

This activity controls which genes are turned on or off, which affects a variety of characteristics, including how the organism responds to its environment.

Part of this job involves silencing, or turning off, certain pieces of DNA moving around in an organism’s genome.

These so-called jumping genes, or transposons, can cause damage if left unregulated.

This entire process is controlled by enzymes, but mammals and plants have developed different enzymes to add methyl groups.

“Mammals only have two major enzymes that add methyl groups in one DNA context, whereas plants actually have multiple enzymes that do it in three DNA contexts.” said researcher Professor Xuehua Zhong. Washington University in St. Louis.

“This is the focus of our research. The question is: why do plants need extra methyltransferases?”

“A particular gene or combination of genes contributes to a particular characteristic or trait.”

“If we know exactly how they are regulated, we can find ways to innovate techniques for crop improvement.”

Professor Zhong and his colleagues focused on two enzymes specifically found in plants: CMT3 and CMT2.

Both enzymes are responsible for adding methyl groups to DNA, but CMT3 specializes in one part of DNA called CHG sequences, and CMT2 specializes in another part called CHH sequences.

Despite their functional differences, both enzymes are part of the same chromomethylase (CMT) family and have evolved through duplication events that provide plants with additional copies of genetic information.

We use a common model plant called Thale cress (Arabidopsis), the study authors investigated how these duplicated enzymes evolved different functions over time.

They found that somewhere along the evolutionary timeline, CMT2 lost the ability to methylate CHG sequences. This is because it lacks an important amino acid called arginine.

“Arginine is special because it has an electric charge,” says Jia Gwee, a graduate student at Washington University in St. Louis.

“Because it is positively charged inside cells, it can form hydrogen bonds and other chemical interactions with negatively charged DNA, for example.”

“However, CMT2 contains a different amino acid, valine. Valine is uncharged and therefore cannot recognize CHG contexts like CMT3. We think that is the reason for the difference between the two enzymes. Masu.”

To confirm this evolutionary change, the researchers used a mutation to move arginine back into CMT2.

As expected, CMT2 was able to methylate both CHG and CHH. This suggests that CMT2 is originally a duplicate of CMT3, a backup system to offload as DNA becomes more complex.

“But instead of just copying the original functionality, we developed something new,” Professor Zhong said.

This study also provided insight into the unique structure of CMT2.

This enzyme has a long, flexible N-terminus that controls the stability of its protein.

“This is one of the ways plants have evolved to increase genome stability and combat environmental stress,” Professor Zhong said.

“This feature may explain why CMT2 has evolved in plants growing in very diverse conditions around the world.”

of result Published in today’s diary scientific progress.

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Gwee Others. 2024. scientific progressin press. doi: 10.1126/sciadv.adr2222

Source: www.sci.news

Fresh research illuminates the mechanisms behind the end-Triassic mass extinction

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The end-Triassic extinction is, along with the end-Permian and end-Cretaceous events, the most severe mass extinctions of the past 270 million years. The exact mechanism of the end-Triassic extinction has long been debated, most notably because the carbon dioxide that had accumulated over thousands of years and appeared on the surface from volcanic eruptions was a persistent This caused temperatures to rise to impossible levels and seawater to become more acidic. but, new paper in Proceedings of the National Academy of Sciences I say the opposite. The main cause is not warmth, but cold.

Outcrop areas of Pangea's CAMP rocks are located at the time of CAMP (201 million year ago). and the Central High Atlas (CHA) Basin of Morocco. Image credit: Kent others., doi: 10.1073/pnas.2415486121.

The end-Triassic mass extinction occurred 201,564,000 years ago, resulting in the extinction of approximately 76% of all marine and terrestrial species.

This mass extinction coincided with a massive volcanic eruption that split the supercontinent Pangea.

millions of kilometers3 Over 600,000 years, lava erupted and separated what is now the Americas, Europe, and North Africa.

This event marked the end of the Triassic period and the beginning of the Jurassic period. The Jurassic period was the period when dinosaurs appeared to replace the Triassic period creatures and dominated the Earth.

A new study provides evidence that the first lava pulses that ended the Triassic period were extraordinary events that each lasted less than a century, rather than hundreds of thousands of years.

During this condensed time frame, sunlight-reflecting sulfate particles spewed into the atmosphere, cooling the Earth and freezing many of its inhabitants.

A gradual rise in temperature in an already hot environment (carbon dioxide in the atmosphere during the Late Triassic was already three times higher than today's levels) may have finished the job later, but it caused the most damage. It was a volcanic winter.

“Carbon dioxide and sulfate not only act in opposite ways, but in opposite time frames,” said Dr. Dennis Kent, a researcher at the Lamont-Doherty Earth Observatory.

“While it takes a long time for carbon dioxide to build up and heat up objects, the effects of sulfates are almost instantaneous. It takes us into the realm of human grasp. These The events happened in a lifetime.”

The Triassic-Jurassic extinction has long been thought to be related to so-called atmospheric eruptions. mid-atlantic magma zone (camp).

In their study, Dr. Kent and colleagues correlated data from CAMP deposits in the mountains of Morocco, along the Bay of Fundy in Nova Scotia, and in New Jersey's Newark Basin.

A key piece of evidence is the arrangement of magnetic particles in rocks that record the past drift of Earth's magnetic poles during eruptions.

Through a complex series of processes, this pole is offset from the planet's fixed axis of rotation, or true north, and its position changes by a tenth of a degree each year.

Because of this phenomenon, magnetic particles in lava that are placed within decades of each other all point in the same direction, but those placed, say, thousands of years later, point in different directions by 20 or 30 degrees.

What the researchers discovered were five consecutive early CAMP lava pulses spread over about 40,000 years. Each magnetic grain is aligned in a single direction, indicating that the lava pulse appeared less than 100 years before magnetic drift appeared.

These large eruptions released so much sulfate so quickly that it blocked most of the sun and lowered temperatures.

Unlike carbon dioxide, which lingers for centuries, volcanic sulfate aerosols tend to rain out of the atmosphere within a few years, so the resulting cold snaps don't last very long.

However, due to the speed and scale of the eruptions, these volcanoes' winters were devastating.

Scientists compared the CAMP series to sulfates produced in the 1783 eruption of Iceland's Laki volcano, which caused widespread crop failure. Only the first CAMP pulse was several hundred times larger.

Triassic fossils lie in the sediments just below the CAMP layer. This includes large terrestrial and semi-aquatic relatives of crocodiles, strange tree lizards, giant flat-headed amphibians, and many tropical plants. After that, it disappears with the eruption of CAMP.

Small feathered dinosaurs existed for tens of millions of years before this, surviving along with turtles, true lizards, and mammals, and eventually thriving to become much larger. This is probably because they are small and able to survive in burrows.

“The magnitude of the environmental impact is related to the concentration of events,” said Dr. Paul Olsen, also of the Lamont-Doherty Earth Observatory.

“A small event spread over tens of thousands of years has a much smaller impact than the same amount of volcanic activity concentrated over less than a century.”

“The most important implication is that CAMP's lava represents an unusually concentrated event.”

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Dennis V. Kent others. 2024. Correlation of sub-centennial-scale pulses of early mid-Atlantic magmatic field lavas and the end-Triassic extinction. PNAS 121 (46): e2415486121;doi: 10.1073/pnas.2415486121

Source: www.sci.news

The Mechanisms of Anticipating the Beat Drop in Your Brain

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We are able to enjoy music because of our ability to recognize musical boundaries.

NDAB Creativity/Shutterstock

We may finally understand how the brain processes beat drops: People use two distinct brain networks to predict and identify the transitions between musical segments.

Musical boundaries – the moments when one part of a composition ends and another begins – are important to enjoying music, especially in the Western musical tradition. Without them, he says, your favorite hits can sound like a monotonous, random stream of notes, “like reading a text without punctuation.” Ibarra Burnat Perez At the University of Jyväskylä, Finland.

To understand how the brain processes musical boundaries, she and her colleagues analyzed brain activity while listening to 36 adults listen to instrumental pieces from three different genres: Adios Nonino Astor Piazzolla, an American progressive metal band Stream of consciousness Dream Theater and Russian Ballet Classics of Spring Festival Works by Igor Stravinsky. All of the listeners had attended school in Finland, and half of them considered themselves semi-professional or professional musicians.

The researchers found that just before musical boundaries, a brain network they call the early auditory network activates in anticipation of the end of a musical phrase. This network primarily involves auditory regions located in the posterior, or back, outer region of the brain called the cortex.

Another network becomes active during and after musical transitions. This network, called the border-transition network, is characterized by increased activity in auditory areas toward the middle and anterior, or front, parts of the cortex. Perez says that this change in brain activity between the two regions is similar to how the brain understands the difference between sentences in a language.

During and after the musical boundary, several brain regions, including the right ventrolateral prefrontal cortex, which is involved in complex cognitive tasks and decision-making, deactivate, suggesting that the brain redirects attention and resources to integrating new musical information as a new segment begins, Perez says.

Musicians and non-musicians also used these two brain networks differently. For example, musicians relied on brain regions important for higher-order auditory processing and integration, which may reflect a more specialized approach to understanding musical boundaries, Perez says. Non-musicians, on the other hand, showed greater connectivity across broader brain regions, indicating a more general approach.

In addition to shedding light on how the brain processes music, Perez says, these findings could also help develop music therapy for people who have difficulty comprehending language. For example, incorporating elements of musical boundaries into speech transitions (such as matching syllables to a melody) might make sentences easier to understand, she says.

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Source: www.newscientist.com

Mechanisms controlling interactions between sensory and memory nervous systems identified by scientists

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The classical understanding of brain organization is that the brain's perceptual areas represent the world 'as it is', and the brain's visual cortex represents the external world 'retinolocally', based on how light hits the retina. That's what it means. In contrast, the brain's memory areas are thought to represent information in an abstract form, stripped of details about physical properties. Now, a team of neuroscientists from Dartmouth College and the University of Edinburgh have identified the neural coding mechanisms that allow information to move back and forth between the brain's sensory and memory regions.

Traditional views of brain organization suggest that regions at the top of the cortical hierarchy process internally directed information using abstract, amodal neural codes. Nevertheless, recent reports have described the presence of retinotopic coding at cortical vertices, including the default mode network.What is the functional role of retinal local coding at the apex of the cortical hierarchy? Steel other. We report that retinotopic coding structures interactions between internally oriented (memory) and externally oriented (perception) brain regions. Image credit: Gerd Altmann.

“We now know that brain regions associated with memory encode the world, like a 'photo negative' of the universe,” said Dr. Adam Steele, a researcher at Dartmouth College.

“And that 'negativity' is part of the mechanism that moves information in and out of memory, and between perceptual and memory systems.”

In a series of experiments, participants were tested on perception and memory while their brain activity was recorded using a functional magnetic resonance imaging (fMRI) scanner.

Dr. Steele and his colleagues identified a contralateral push-pull-like coding mechanism that governs the interaction between perceptual and memory areas in the brain.

The results showed that when light hits the retina, the brain's visual cortex responds by increasing activity that represents the pattern of light.

Memory areas of the brain also respond to visual stimuli, but unlike visual areas, processing the same visual pattern reduces neural activity.

“There are three unusual findings in this study,” the researchers said.

“The first is the discovery that visual coding principles are stored in the memory system.”

“The second thing is that this visual code is upside down in our memory system.”

“When you see something in your visual field, neurons in your visual cortex become active and neurons in your memory system quiet down.”

“Third, this relationship is reversed during memory recall.”

“If you close your eyes and recall that visual stimulus in the same space, the relationship is reversed. Your memory system kicks in and suppresses the neurons in your sensory area.”

Dr Ed Shilson, a neuroscientist at the University of Edinburgh, said: “Our findings demonstrate how shared visual information is used by the memory system to bring recalled memories into and out of focus. “This provides a clear example of how this can be done.”

of study Published in today's magazine natural neuroscience.

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A. Steel other. Retinotopic codes structure interactions between perceptual and memory systems. nut neurosi, published online on January 2, 2024. doi: 10.1038/s41593-023-01512-3

Source: www.sci.news

New Study Unveils the Reasons and Mechanisms behind Some Cats’ Fetch-playing Behavior

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A recent study delved into the play preferences of cats and discovered that cats enjoy having control over when, where, and how they play. This finding sheds light on how to encourage cats to play fetch.

According to research published in Scientific Reports, scientists found that cats initiated and concluded the fetch game more frequently than their owners. And, when the cats were the ones to start the game, they played for a longer duration compared to when their owners initiated the game.

Interestingly, cats actually continued playing for longer periods even after their owners had stopped the game. This suggests that while cats seem to be in control of the fetch game, they are willing to continue playing as long as they are allowed to.

This study, announced in Scientific Reports, surveyed 924 cat owners with cats who play fetch, involving 1,154 current or former cats.

The study revealed that fetching cats typically have favorite items to retrieve and play with, often opting for various household objects over toys, especially those that are mouse-sized, such as hair ties or bottle tops.

Moreover, these cats tend to have a preferred family member and location for playing and fetching. The researchers from the University of Sussex, including Gemma Forman, noted that cats show a preference for bedrooms and stairs, with different heights adding to their interest in playing.

But why do some cats play fetch?

Researchers speculate that fetching behavior mirrors hunting behavior, but with an added element of social interaction with their owner, creating a unique interspecific dynamic that is not commonly observed in cats.

Among purebred cats, Siamese cats are more likely to engage in fetch, while mixed-breed cats exhibit higher involvement in the fetch game.

For pet owners who are not professional pet trainers, the study offered some encouragement – 94% of pet owners reported that their cats started playing fetch without needing to be taught. Additionally, most cats begin fetching at a young age, with 61% of the cats in the study starting before they were one year old.

Gemma Forman, one of the study authors, emphasized the importance of being open and accepting of their cat’s needs and behaviors, as their cat might have already indicated its desire to play, even if communicating this need can be challenging.

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Source: www.sciencefocus.com