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Comment by Dr. Krishna Kumari Challa on July 16, 2021 at 9:30am

Part 2: 

The researchers experimented with several variables to see how they impacted Physarum's growth decisions, and noticed something unusual: when they stacked the same three discs on top of each other, the organism seemed to lose its ability to distinguish between the three discs and the single disc. It grew toward both sides of the dish at roughly equal rates, despite the fact that the three stacked discs still had greater mass. Clearly, Physarum was using another factor beyond mass to decide where to grow.

To figure out the missing piece of the puzzle, the scientists used computer modeling to create a simulation of their experiment to explore how changing the mass of the discs would impact the amount of stress (force) and strain (deformation) applied to the semi-flexible gel and the attached growing Physarum. As they expected, larger masses increased the amount of strain, but the simulation revealed that the strain patterns the masses produced changed, depending on the arrangement of the discs.

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But how was it detecting these strain patterns? The scientists suspected it had to do with Physarum's ability to rhythmically contract and tug on its substrate, because the pulsing and sensing of the resultant changes in substrate deformation allows the organism to gain information about its surroundings. 

Advanced Materials (2021). DOI: 10.1002/adma.202008161

https://phys.org/news/2021-07-brain-brainless-slime-molds-reveal.ht...

Comment by Dr. Krishna Kumari Challa on July 16, 2021 at 9:29am

Thinking without a brain: Studies in brainless slime molds reveal that they use physical cues to decide where to grow

Scientists  have discovered that a brainless slime mold called Physarum polycephalum uses its body to sense mechanical cues in its surrounding environment, and performs computations similar to what we call "thinking" to decide in which direction to grow based on that information. Unlike previous studies with Physarum, these results were obtained without giving the organism any food or chemical signals to influence its behavior. The study is published in Advanced Materials.

Physarum is interesting because it doesn't have a brain but it can still perform a lot of the behaviours that we associate with thinking, like solving mazes, learning new things, and predicting events. Figuring out how proto-intelligent life manages to do this type of computation gives us more insight into the underpinnings of animal cognition and behavior, including our own.

The team's research demonstrated that this brainless creature was not simply growing toward the heaviest thing it could sense—it was making a calculated decision about where to grow based on the relative patterns of strain it detected in its environment.

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Slime molds are amoeba-like organisms that can grow to be up to several feet long, and help break down decomposing matter in the environment like rotting logs, mulch, and dead leaves. A single Physarum creature consists of a membrane containing many cellular nuclei floating within a shared cytoplasm, creating a structure called a syncytium. Physarum moves by shuttling its watery cytoplasm back and forth throughout the entire length of its body in regular waves, a unique process known as shuttle streaming. With most animals, we can't see what's changing inside the brain as the animal makes decisions. Physarum offers a really exciting scientific opportunity because we can observe its decisions about where to move in real-time by watching how its shuttle streaming behavior changes.

While previous studies have shown that Physarum moves in response to chemicals and light, Murugan and her team wanted to know if it could make decisions about where to move based on physical cues in its environment alone.

The researchers placed Physarum specimens in the center of petri dishes coated with a semi-flexible agar gel and placed either one or three small glass discs next to each other atop the gel on opposite sides of each dish. They then allowed the organisms to grow freely in the dark over the course of 24 hours, and tracked their growth patterns. For the first 12 to 14 hours, the Physarum grew outwards evenly in all directions; after that, however, the specimens extended a long branch that grew directly over the surface of the gel toward the three-disc region 70% of the time. Remarkably, the Physarum chose to grow toward the greater mass without first physically exploring the area to confirm that it did indeed contain the larger object.

Comment by Dr. Krishna Kumari Challa on July 16, 2021 at 9:23am

Human cells harness power of detergents to wipe out bacteria

Cells, like many of us, fend off germs with cleaning products. Researchers have discovered that a molecule made throughout much of the body wipes out invading bacteria like a detergent attacking an oily stain.

This killer cleaner, a protein known as APOL3, thwarts infections by dissolving bacterial membranes. Researchers tested the protein on the food-poisoning bacteria Salmonella and other similar microbes.

The work offers new insight into how human cells defend themselves against infection, a process termed cell-autonomous immunity. While scientists knew that cells could attack bacterial membranes, this study uncovers what appears to be the first example of a protective intracellular protein with detergent-like action.

"A human apolipoprotein L with detergent-like activity kills intracellular pathogens" Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abf8113

https://phys.org/news/2021-07-human-cells-harness-power-detergents....

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Comment by Dr. Krishna Kumari Challa on July 15, 2021 at 10:56am

Glass octopus moving in the deep sea

Marine biologists spotted the elusive glass octopus (Vitreledonella richardi) during a 34-day expedition off the remote Phoenix Islands

Comment by Dr. Krishna Kumari Challa on July 15, 2021 at 10:15am

The Story of Primary Plastid Endosymbiosis: How Algae and Plants became Photosynthetic

Comment by Dr. Krishna Kumari Challa on July 15, 2021 at 10:03am

New spray could someday help heal damage after a heart attack

Heart attack, or myocardial infarction, is one of the leading causes of death worldwide. Although modern surgical techniques, diagnostics and medications have greatly improved early survival from these events, many patients struggle with the long-term effects of permanently damaged tissue, and the 5-year mortality rate remains high. Now, researchers reporting in ACS Nano have developed a minimally invasive exosome spray that helped repair rat hearts after myocardial infarction.

Comment by Dr. Krishna Kumari Challa on July 15, 2021 at 9:43am

Quantum physics helps destroy cancer cells

Cancer cell death is triggered within three days when X-rays are focused on tumor tissue containing iodine-carrying nanoparticles. The iodine releases electrons that break the tumor's DNA, leading to cell death.

Exposing a metal to light leads to the release of electrons, a phenomenon called the photoelectric effect. An explanation of this phenomenon by Albert Einstein in 1905 heralded the birth of quantum physics. This research now research provides evidence that suggests it is possible to reproduce this effect inside cancer cells.

A longstanding problem with cancer radiation therapy is that it is not effective at the center of tumors, where oxygen levels are low due to the lack of deep-penetrating blood vessels. X-ray irradiation needs oxygen to generate DNA-damaging reactive oxygen when the rays hit molecules inside the cell.

Researchers have been trying to overcome this issue by finding more direct ways to damage cancer DNA. In earlier work, they showed that gadolinium-loaded nanoparticles could kill cancer cells when irradiated with 50.25 kiloelectron volts of synchrotron-generated X-rays.

In the current study, they designed porous, iodine-carrying organosilica nanoparticles. Iodine is cheaper than gadolinium and releases electrons at lower energy levels.

The researchers dispersed their nanoparticles through tumor spheroids, 3D tissue containing multiple cancer cells. Irradiating the spheroids for 30 minutes with 33.2 keV of X-rays led to their complete destruction within three days. By systematically changing energy levels, they were able to demonstrate that the optimum effect of tumor destruction occurs with 33.2 keV X-ray. Further analyses showed that the nanoparticles were taken up by the tumor cells, localizing just outside their nuclei. Shining just the right amount of X-ray energy onto the tissue prompted iodine to release electrons, which then caused double-strand breaks in the nuclear DNA, triggering cell death. 

Yuya Higashi et al, Iodine containing porous organosilica nanoparticles trigger tumor spheroids destruction upon monochromatic X-ray irradiation: DNA breaks and K-edge energy X-ray, Scientific Reports (2021). DOI: 10.1038/s41598-021-93429-9

https://phys.org/news/2021-07-quantum-physics-cancer-cells.html?utm...

Comment by Dr. Krishna Kumari Challa on July 14, 2021 at 9:42am

When the human brain goes diving

7,108 views • 23 Jun 2021 • Visualisation showing the physiological responses of a freediver making a breath-hold dive to 107m - including heart rate, arterial blood oxygen saturation and cerebral blood oxygen saturation. Physiological responses were measured using non-invasive, wearable near-infrared spectroscopy. Here's a link to the published work - McKnight et al 2021, When the human brain goes diving: using near-infrared spectroscopy to measure cerebral and systemic cardiovascular responses to deep, breath-hold diving in elite freedivers: https://doi.org/10.1098/rstb.2020.0349

Comment by Dr. Krishna Kumari Challa on July 14, 2021 at 9:23am

Gene editing 'blocks virus transmission' in human cells

Scientists have used CRISPR gene-editing technology to successfully block the transmission of the SARS-CoV-2 virus in infected human cells, according to research released recently that could pave the way for COVID-19 treatments.

Writing in the journal Nature Communications, researchers in Australia said the tool was effective against viral transmissions in lab tests, adding that they hoped to begin animal trials soon.

CRISPR, which allows scientists to alter DNA sequences and modify gene function, has already shown promise in eliminating the genetic coding that drives the development of children's cancer.

The team in Tuesday's study used an enzyme, CRISPR-Cas13b, that binds to relevant RNA sequences on the novel coronavirus and degrades the genome it needs to replicate inside human cells.

 The team had designed the CRISPR tool to recognize SARS-CoV-2, the virus responsibly for COVID-19.

Once the virus is recognized, the CRISPR enzyme is activated and chops up the virus.

Mohamed Fareh et al, Reprogrammed CRISPR-Cas13b suppresses SARS-CoV-2 replication and circumvents its mutational escape through mismatch tolerance, Nature Communications (2021). DOI: 10.1038/s41467-021-24577-9

https://phys.org/news/2021-07-gene-blocks-virus-transmission-human....

Comment by Dr. Krishna Kumari Challa on July 14, 2021 at 9:17am

Tree rings show record of newly identified extreme solar activity event

The sun constantly emits a stream of energetic particles, some of which reach Earth. The density and energy of this stream form the basis of space weather, which can interfere with the operation of satellites and other spacecraft. A key unresolved question in the field is the frequency with which the sun emits bursts of energetic particles strong enough to disable or destroy space-based electronics.

One promising avenue for determining the rate of such events is the dendrochronological record. This approach relies on the process by which a solar energetic particle (SEP) strikes the atmosphere, causing a chain reaction that results in the production of an atom of carbon-14. This atom subsequently can be incorporated into the structure of a tree; thus, the concentration of carbon-14 atoms in a tree ring can indicate the impact rate of SEPs in a given year.

To date, three events of extreme SEP production are well described in literature, occurring approximately in the years 660 BCE, 774–775 CE, and 992–993 CE. Each event was roughly an order of magnitude stronger than any measured in the space exploration era. Miyake et al. describe such an event, which occurred between 5411 BCE and 5410 BCE. Because of this burst, atmospheric carbon-14 increased 0.6 percent year over year in the Northern Hemisphere and was sustained for several years before dropping to typical levels.

Using statistical methods, the researchers identified a pattern of small carbon-14 fluctuations consistent with the sun's 11-year solar cycle; the event recorded in the tree ring occurred during a time of solar maximum. Notably, other evidence suggests that the sun was also undergoing a decades-long period of increasing activity.

If an extreme SEP burst is indeed the cause of the additional carbon-14, then these observations could aid in forecasting future events. However, tree ring  measurements cannot rule out other extraterrestrial causes, such as a nearby supernova explosion. Confirmation will require isotopic measurements of beryllium and chlorine taken from ice cores, according to the authors.

F. Miyake et al, A Single‐Year Cosmic Ray Event at 5410 BCE Registered in 14 C of Tree Rings, Geophysical Research Letters (2021). DOI: 10.1029/2021GL093419

https://phys.org/news/2021-07-tree-newly-extreme-solar-event.html?u...

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