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Comment by Dr. Krishna Kumari Challa on May 28, 2021 at 10:28am

How plants ward off a dangerous world of pathogens

The world's plants, immobile and rooted in soil which contains potentially lethal micro-organisms, face a constant threat from invading pathogens. In recent years, however, scientists have discovered that plant species employ sophisticated immune strategies that differ from —but also shares similarities with—the ways humans combat infections.

Now scientists describe a key molecular "on-off" switch that enables plants to mobilize immunity in the face of microbial pathogens. The findings not only have direct implications for crop management and possibly protecting plants from the effects of climate change, but also for better understanding the human immune system as well.

Plants  have many innate immune gene families that are similar to ours, and historically plants have been used to establish fundamental principles of host defenses and disease tolerance.

Unlike humans, plants lack an adaptive immune system that "remembers" specific pathogens and then organizes a tailored defense. In the study, researchers explored the sophisticated cell-autonomous defense programs that plants do employ against pathogens. It turns out that what they lack in tailored antibodies, they make up for by greatly expanding their repertoire of innate immune responses, which mount a more generalized defense against all infections.

For instance, one of these strategies involves innate immune proteins that morph into a "gel-like" state in order to trigger immune responses. This process—called liquid-liquid phase separation—enables biological activities to be concentrated in membrane-less compartments inside cells. The researchers discovered that plant immune proteins, known as guanylate-binding protein-like (GBPL) GTPases, create liquid-like compartments within the nucleus that creates a concentration of proteins that drive the activity of host defense genes during infection. This phase-separated compartment also excludes inhibitory proteins to the outside of the nucleus as part of a spatially separated "on-off" switch.

Liquid-liquid phase separation is a new frontier in understanding how cells compartmentalize their biological activities.

All organisms, from single-celled bacteria to plants  to humans, defend their genome from outside threats. "Phase-separation may be a pervasive evolutionary mechanism to organize these defense activities as part of the cell-autonomous immune response."

Shuai Huang et al, A phase-separated nuclear GBPL circuit controls immunity in plants, Nature (2021). DOI: 10.1038/s41586-021-03572-6

https://phys.org/news/2021-05-ward-dangerous-world-pathogens.html?u...

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Comment by Dr. Krishna Kumari Challa on May 28, 2021 at 10:16am

Biologists construct a 'periodic table' for cell nuclei

One hundred fifty years ago, Dmitri Mendeleev created the periodic table, a system for classifying atoms based on the properties of their nuclei. This week, a team of biologists studying the tree of life has unveiled a new classification system for cell nuclei and discovered a method for transmuting one type of cell nucleus into another.

Scientists had been working together to classify how chromosomes, which can be several meters long, fold up to fit inside the nuclei of different species from across the tree of life.

The team realized it was just seeing variants on two overall nuclear designs. In some species, chromosomes are organized like the pages of a printed newspaper, with the outer margins on one side and the folded middle at the other. And then in other species, each chromosome is crumpled into a little ball.

The data implied that over the course of evolution, species can switch back and forth from one type to the other.

 Computer simulations showed that by destroying condensin II ( a protein that plays a role in how cells divide), you could make a human nucleus reorganize to resemble a fly nucleus.

"3D genomics across the tree of life reveals condensin II as a determinant of architecture type" Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abe2218

https://phys.org/news/2021-05-biologists-periodic-table-cell-nuclei...

Comment by Dr. Krishna Kumari Challa on May 28, 2021 at 10:09am

153 years after discovery of the immune system's dendritic cells, scientists uncover a new subset

When pathogens invade or tumor cells emerge, the immune system is alerted by danger signals that summon a key battalion of first responders, the unsung heroes of the immune system—a population of starfish-shaped sentinels called dendritic cells.

Without them, coordination of the immune response would be slower and less-well organized. Yet even in the face of such an indispensable role, it has taken until now to discover how a sub-population of these cells doesn't perish after completing their primary job in the immune system.

Dendritic cells were discovered in 1868, and at that time were misunderstood and wrongly categorized as members of the nervous system. But immunologists now know there are different types of these cells, even though they all look alike and have roughly the same job as sentinels in the immune system –on patrol 24/7, hunting down infiltrating causes of infection and disease. What separates one group from another, scientists in Germany have just found, is their response to certain signaling molecules and how long they survive in tissues and the blood.

First off, the shape is no accident of nature. It allows these cells to perform their primary role, which involves obtaining microscopic samples—antigens—from an infiltrator slated for destruction. Dendritic cells engulf snippets of the invader and literally present those antigens to key warriors of the immune system.

These highly mobile cells travel to sites where disease-killing immune cells reside to present their samples, introducing T cells, for example, to the enemy that awaits. Formally, the activity of presenting the sample to T cells is called antigen presentation. For all the work involved with alerting the body to danger, a major group of dendritic cells is programmed to die after a job well done.

Now, in a groundbreaking series of studies, a large team of researchers from throughout Germany has discovered why a unique population of dendritic cells doesn't die after antigen presentation. The sub-population continues to stimulate parts of the immune system to aid the fight against invasive viruses, bacteria or potentially deadly tumour cells.

Lukas Hatscher et al. Select hyperactivating NLRP3 ligands enhance the TH1- and TH17-inducing potential of human type 2 conventional dendritic cells, Science Signaling (2021) DOI: 10.1126/scisignal.abe1757

https://medicalxpress.com/news/2021-05-years-discovery-immune-dendr...

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Comment by Dr. Krishna Kumari Challa on May 27, 2021 at 8:56am

Memory details fade over time, with only the main gist preserved

What information is retained in a memory over time, and which parts get lost? These questions have led to many scientific theories over the years, and now a team of researchers  have been able to provide some answers.

Their new study, which is published today in Nature Communications, demonstrates that our memories become less vibrant and detailed over time, with only the central gist eventually preserved. Moreover, this 'gistification' of our memories is boosted when we frequently recall our recent experiences.

Nature Communications (2021). DOI: 10.1038/s41467-021-23288-5

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The work could have implications in a number of areas, including the nature of memories in post-traumatic stress disorder, the repeated questioning of eye-witness testimonies and even in best practice for exam studying.

While memories are not exact carbon copies of the past—remembering is understood to be a highly reconstructive process—experts have suggested that the contents of a memory could change each time we bring it back to mind.

However, exactly how our memories differ from the original experiences, and how they are transformed over time, has until now proven difficult to measure in laboratory settings.

https://medicalxpress.com/news/2021-05-memory-main-gist.html?utm_so...

Comment by Dr. Krishna Kumari Challa on May 27, 2021 at 8:49am

Resetting the biological clock by flipping a switch

The biological clock is present in almost all cells of an organism. As more and more evidence emerges that clocks in certain organs could be out of sync, there is a need to investigate and reset these clocks locally. Scientists  introduced a light-controlled on/off switch to a kinase inhibitor, which affects clock function. This gives them control of the biological clock in cultured cells and explanted tissue. They published their results on 26 May in Nature Communications.

Life on Earth has evolved under a 24-hour cycle of light and dark, hot and cold. "As a result, our cells are synchronized to these 24-hour oscillations. Our circadian clock is regulated by a central controller in the suprachiasmatic nucleus, a region in the brain directly above the optic nerve, but all our cells contain a clock of their own. These clocks consist of an oscillation in the production and breakdown of certain proteins.

It is becoming increasingly clear that these clocks can be disrupted in organs or tissues, which may lead to disease. We know very little about how our cells coordinate these oscillations, or how it affects the body.

To study these effects, it would be useful to have a drug that affects the clocks and that can be activated locally. Researchers now  created several compounds, such as antibiotics or anticancer drugs, that could be switched on and off with light.

They  developed a kinase inhibitor, longdaysin, which slows down the circadian clock to a cycle that lasts up to 48 hours. They fitted this longdaysin with a light switch that allowed them to activate or deactivate the compound with violet and green light, respectively.

Reversible modulation of circadian time with chronophotopharmacology, Nature Communications (2021). DOI: 10.1038/s41467-021-23301-x

https://phys.org/news/2021-05-resetting-biological-clock-flipping.h...

Comment by Dr. Krishna Kumari Challa on May 26, 2021 at 10:16am

First hacker-resistant cloud software system

Up to now, there has been no way to guarantee that a software system is secure from bugs, hackers, and vulnerabilities.

Researchers may now have solved this security issue. They have developed SeKVM, the first system that guarantees—through a mathematical proof—the security of virtual machines in the cloud. In a new paper to be presented on May 26, 2021, at the 42nd IEEE Symposium on Security & Privacy, the researchers hope to lay the foundation for future innovations in system software verification, leading to a new generation of cyber-resilient system software.

SeKVM is the first formally verified system for cloud computing. Formal verification is a critical step as it is the process of proving that software is mathematically correct, that the program's code works as it should, and there are no hidden security bugs to worry about.

This is the first time that a real-world multiprocessor software system has been shown to be mathematically correct and secure. This means that users' data are correctly managed by software running in the cloud and are safe from security bugs and hackers.

A Secure and Formally Verified Linux KVM Hypervisor, DOI: 10.1109/SP40001.2021.00049

https://techxplore.com/news/2021-05-team-hacker-resistant-cloud-sof...

Comment by Dr. Krishna Kumari Challa on May 26, 2021 at 10:00am

New insights into how phytochromes help plants sense and react to light, temperature

Plants contain several types of specialized light-sensitive proteins that measure light by changing shape upon light absorption. Chief among these are the phytochromes.

Phytochromes help plants detect light direction, intensity and duration; the time of day; whether it is the beginning, middle or end of a season; and even the color of light, which is important for avoiding shade from other plants. Remarkably, phytochromes also help plants detect temperature.

New research  helps explain how the handful of phytochromes found in every plant respond differently to light intensity and temperature, thus enabling land plants to colonize the planet many millions of years ago and allowing them to acclimate to a wide array of terrestrial environments.

For the first time, these biologists fully characterized the phytochrome family from the common model plant Arabidopsis thaliana on a biochemical level.

The scientists also extended that characterization into the phytochromes of two important food crops: corn and potatoes. Instead of finding that all phytochrome isoforms are identical, they found surprising differences.

A deeper understanding of these proteins will allow scientists to use phytochromes as tools both in agriculture and for research in the field of optogenetics, which has exploited phytochromes to precisely control cellular events simply by shining light.

E. Sethe Burgie el al., "Differing biophysical properties underpin the unique signaling potentials within the plant phytochrome photoreceptor families," PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2105649118

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Plants typically express three or more phytochromes. It was well-known that plants can respond to wide ranges of light intensities but other factors such as expression levels and signaling potential were considered as the likely culprits.

"Now we know that the differing biophysical properties of the isoforms also underpin the unique signaling potentials within the plant phytochrome photoreceptor families," Vierstra said. "These properties are evident in Phy families in plants ranging from Arabidopsis to maize and potatoes, indicating that they likely emerged very early in phytochrome evolution."

https://phys.org/news/2021-05-insights-phytochromes-react-temperatu...

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Comment by Dr. Krishna Kumari Challa on May 25, 2021 at 12:53pm

Metabolic hormon 'leptin' linked to vaccine response

Reduced levels of a metabolic hormone known as leptin is linked to poor vaccine antibody responses in the general population, a University of Queensland study has found. The researchers made the discovery while investigating several cohorts responses to the influenza vaccine or hepatitis B vaccine pre-COVID. UQs Professor Di Yu identified a link between the metabolic and immune systems that could be used to develop new strategies for improving vaccine protection in vulnerable populations. Using multiple advanced techniques in immunology, genetics and biochemistry, our study found leptin directly promoted the development and function of cells which are vital in triggering an antibody response, Professor Yu said. In collaboration with global teams, we identified the reduction of an essential metabolic hormone called leptin was associated with compromised vaccine responses in both young and older individual ..

Comment by Dr. Krishna Kumari Challa on May 25, 2021 at 12:37pm

The sniffer dogs detecting coronavirus

Comment by Dr. Krishna Kumari Challa on May 25, 2021 at 11:13am

ScienceCasts: The Mystery of Coronal Heating

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