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Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:56am

World’s largest organism found in Australia

Single hybrid seagrass plant now stretches across 180 kilometers

Two closely related species hybridize and create a superorganism whose growth and expansion seems unstoppable. That’s what’s happened in Western Australia’s Shark Bay, researchers say, where a seagrass meadow (see above) stemming from a single hybrid plant has extended its reach across more than 180 kilometers—an area the size of Washington, D.C. Two years ago, scientists discovered some of the seagrass there was a clone of a Poseidon’s ribbon weed (Posidonia australis) that had 40 chromosomes instead of the typical 20. They think half those chromosomes may come from the ribbon weed and half from an unknown species. That second half appears to have provided a big survival advantage, as this hybrid has taken over all but one of the 10 seagrass meadows surveyed, the scientists report today in the Proceedings of the Royal Society B. The clone is about 1.5 orders of magnitude larger than the largest fungi and the longest sea animal. The team suspects the clone arose 4500 years ago and has been spreading ever since. That would make it among the oldest organisms on Earth, although not quite as old as the oldest tree. Shark Bay is at the northern edge of where this seagrass can survive, and global warming is making it harder for the plants to hang on there. Low rainfall and high evaporation rates have also caused the water to become much saltier. The clone’s extra genes may be providing a way for it to adapt to these stresses, the authors note.

https://www.science.org/content/article/world-s-largest-organism-fo...

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:52am

How wingless salamanders fly

From frogs remaining airborne using their webbed feet to lizards and snakes gliding by expanding their ribcages, biologists might have thought they had seen every unusual aerial strategy — but now they report flying salamanders.

https://www.nature.com/articles/d41586-022-01375-x

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:45am

How moonlight fine-tunes animal reproduction

Animals possess circadian clocks, or 24-hour oscillators, to regulate daily behaviour. These typically take their cues from the periodic change of sunlight and darkness. However, many animals are also exposed to moonlight, which reoccurs with ~25h periodicity.

Researchers have now discovered that moonlight adjusts the daily clock of marine bristle worms, which helps them to fine-tune their reproductive cycle to certain hours during the night. The study, published in the Proceedings of the National Academy of Sciences, provides an explanation for the phenomenon that daily clocks from flies to humans can exhibit plastic run-times.

In order to produce the next generation, the marine bristle worm Platynereis dumerilii releases its eggs and sperm freely into the open seawater. The correct timing of their reproductive cycles is therefore essential for the survival of the species. It was already known that bristle worms schedule their reproduction to few days of the month. Now, the researchers uncovered that they also synchronize to very specific hours during each night.

Moonlight determines when, precisely, during the night the worms start their reproductive behavior, which is always during the darkest portion of the night.

Rather than acting as the direct stimulus for swarming, moonlight changes the circadian clock period length. In nature, the time of moonlight changes every day by about 50 minutes. The plasticity of the clock allows the worms to factor in these changes. 

 Humans show such circadian plasticity, too. For instance, patients with bipolar disorder exhibit enigmatic circalunidian (i.e. 24.8h) periods correlated with their mood switches. The scientists hope that their work will help to understand the origin and consequences of biological timer plasticity, as well as its interplay with natural timing cues.

Martin Zurl et al, Two light sensors decode moonlight versus sunlight to adjust a plastic circadian/circalunidian clock to moon phase, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2115725119

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:37am

Alzheimer's disease causes cells to overheat and 'fry like eggs'

Researchers have shown that aggregation of amyloid-beta, one of two key proteins implicated in Alzheimer's disease, causes cells to overheat and "fry like eggs."

The researchers  used sensors small and sensitive enough to detect temperature changes inside individual cells , and found that as amyloid-beta  misfolds and clumps together, it causes cells to overheat.

In an experiment using human cell lines, the researchers found the heat released by amyloid-beta aggregation could potentially cause other, healthy amyloid-beta to aggregate, causing more and more aggregates to form.

The researchers used tiny temperature sensors called fluorescent polymeric thermometers (FTPs) to study the link between aggregation and temperature. They added amyloid-beta to human cell lines to kickstart the aggregation process and used a chemical called FCCP as a control, since it is known to induce an increase in temperature.

They found that as amyloid-beta started to form thread-like aggregates called fibrils, the average temperature of the cells started to rise. The increase in cellular temperature was significant compared to cells that did not have any amyloid-beta added.

As the fibrils start elongating, they release energy in the form of heat. Amyloid-beta aggregation requires quite a lot of energy to get going, but once the aggregation process starts, it speeds up and releases more heat, allowing more aggregates to form.

Once the aggregates have formed, they can exit the cell and be taken up by neighboring cells, infecting healthy amyloid-beta in those cells.

In the same series of experiments, the researchers also showed that amyloid-beta aggregation can be stopped, and the cell temperature lowered, with the addition of a drug compound. The experiments also suggest that the compound has potential as a therapeutic for Alzheimer's disease, although extensive tests and clinical trials would first be required.

Using a drug that inhibits amyloid-beta aggregation, the researchers were able to pinpoint the fibrils as the cause of thermogenesis. It had previously been unknown whether protein aggregation or potential damage to mitochondria—the "batteries" that power cells—was responsible for this phenomenon.

The researchers say their assay could be used as a diagnostic tool for Alzheimer's disease, or to screen potential drug candidates.

Chyi Wei Chung et al, Intracellular Aβ42 Aggregation Leads to Cellular Thermogenesis, Journal of the American Chemical Society (2022). DOI: 10.1021/jacs.2c03599

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:28am

Science academies publish statements on primary concerns for international action ahead of the G7 summit

The science academies of the G7 states are calling for urgent international action to protect the ocean and polar regions and to accelerate decarbonization. In the healthcare sector, scientists demand increased global pandemic preparedness and the implementation of a One Health approach, which considers the health of humans, animals, plants and the wider environment as closely linked and interdependent. Their recommendations are set out in four statements which were submitted to the German federal government today at the Science7 Dialogue Forum 2022 in Berlin/Germany.

https://www.leopoldina.org/en/events/event/event/2962/

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 8:04am

A world first: Human liver was treated in a machine and then successfully transplanted

The Liver4Life research has developed a perfusion machine that makes it possible to implant a human organ into a patient after a storage period of three days outside a body. The machine mimics the human body as accurately as possible, in order to provide ideal conditions for human livers. A pump serves as a replacement heart, an oxygenator replaces the lungs and a dialysis unit performs the functions of the kidneys. In addition, numerous hormone and nutrient infusions perform the functions of the intestine and pancreas.

Like the diaphragm in the human body, the machine also moves the liver to the rhythm of human breathing. In January 2020, the multidisciplinary Zurich research team—involving the collaboration of University Hospital Zurich (USZ), ETH Zurich and the University of Zurich (UZH)—demonstrated for the first time that perfusion technology makes it possible to store a liver outside the body for several days.

The team prepared the liver in the machine with various drugs. In this way, it was possible to transform the liver into a good human organ, even though it was originally not approved for transplantation due to its poor quality. The multi-day perfusion—the mechanical circulation of the organ—enables antibiotic or hormonal therapies or the optimization of liver metabolism, for example. In addition, lengthy laboratory or tissue tests can be carried out without time pressure. Under normal circumstances, this is not possible because organs can only be stored for 12 hours if they are stored conventionally on ice and in commercially available perfusion machines.

As part of an approved individual treatment attempt, the doctors gave a cancer patient on the Swiss transplant waiting list the choice of using the treated human liver. Following his consent, the organ was transplanted in May 2021. The patient was able to leave hospital a few days after the transplantation and is now doing well.

Pierre-Alain Clavien, Transplantation of a human liver following 3 days of ex situ normothermic preservation, Nature Biotechnology (2022). DOI: 10.1038/s41587-022-01354-7. www.nature.com/articles/s41587-022-01354-7

Comment by Dr. Krishna Kumari Challa on June 1, 2022 at 7:18am

Driver mutations vs passenger mutations

Comment by Dr. Krishna Kumari Challa on May 30, 2022 at 8:25am

Threat to 6G: Eavesdroppers can hack 6G frequency with DIY metasurface

Comment by Dr. Krishna Kumari Challa on May 29, 2022 at 12:38pm

Why the memory of fear is seared into our brains

Experiencing a frightening event is likely something you’ll never forget. But why does it stay with you when other kinds of occurrences become increasingly difficult to recall with the passage of time?

A team of neuroscientists have been studying the formation of fear memories in the emotional hub of the brain – the amygdala — and think they have a mechanism.

In a nutshell, the researchers found that the stress neurotransmitter norepinephrine, also known as noradrenaline, facilitates fear processing in the brain by stimulating a certain population of inhibitory neurons in the amygdala to generate a repetitive bursting pattern of electrical discharges. This bursting pattern of electrical activity changes the frequency of brain wave oscillation in the amygdala from a resting state to an aroused state that promotes the formation of fear memories.

If you are held up at gunpoint, your brain secretes a bunch of the stress neurotransmitter norepinephrine, akin to an adrenaline rush.

This changes the electrical discharge pattern in specific circuits in your emotional brain, centered in the amygdala, which in turn transitions the brain to a state of heightened arousal that facilitates memory formation, fear memory, since it’s scary. This is the same process, we think, that goes awry in PTSD and makes it so you cannot forget traumatic experiences.

https://www.nature.com/articles/s41467-022-28928-y

https://news.tulane.edu/pr/study-examines-why-memory-fear-seared-ou...

Comment by Dr. Krishna Kumari Challa on May 28, 2022 at 11:06am

How the brain links memories

Our brains rarely record single memories. Instead, they store memories in groups so that the recollection of one significant memory triggers the recall of others that are connected chronologically. As we age, however, our brains gradually lose this ability to link related memories.

Now researchers have discovered a key molecular mechanism behind this memory linking. They’ve also identified a way to restore this brain function genetically in aging mice — and an FDA-approved drug that achieves the same thing.

Published in the journal Nature, the findings suggest a new method for strengthening human memory in middle age and a possible early intervention for dementia.

Brain cells are studded with receptors. To enter a cell, a molecule must latch onto a specific receptor, which operates like a doorknob to provide access inside. The UCLA team focused on a gene that encodes a receptor for CCR5 molecules — the same receptor that HIV hitches a ride on to infect brain cells and cause memory loss in AIDS patients.

As people age, the amount of CCR5 expressed in the brain rises, and increased CCR5 gene expression reduces memory recall.

In the current study, researchers discovered a key mechanism underlying mice’s ability to link memories of their experiences in two different cages. A tiny microscope opened a window into the animals’ brains, enabling the scientists to observe neurons firing and creating new memories.

They found that boosting CCR5 gene expression in the brains of mice interfered with memory linking. The animals forgot the connection between the two cages. But when the scientists deleted the CCR5 gene in the animals, the mice were able to link memories that normal mice could not.

When the researchers gave maraviroc, a drug used for HIV patients, to older mice, the drug duplicated the effect of genetically deleting CCR5 from their DNA. The older animals were able to link memories again.

The finding suggests that beyond reversing the cognitive deficits caused by HIV infection, maraviroc can also be used to help restore middle-aged memory loss.

Yang Shen, Miou Zhou, Denise Cai, Daniel Almeida Filho, Giselle Fernandes, Ying Cai, André F. de Sousa, Min Tian, Nury Kim, Jinsu Lee, Deanna Necula, Chengbin Zhou, Shuoyi Li, Shelbi Salinas, Andy Liu, Xiaoman Kang, Masakazu Kamata, Ayal Lavi, Shan Huang, Tawnie Silva, Won Do Heo, Alcino J. Silva. CCR5 closes the temporal window for memory linking. Nature, 2022; DOI: 10.1038/s41586-022-04783-1

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