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Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 11:12am

Why eyeballing four is easy but five is hard

Our brains use one mechanism to size up four or fewer items, and a different one f... — which is why doing the latter is so much harder. The brain contains specialized neurons that fire when we see a specific number of objects: some fire primarily when presented with one dot on a screen, for example. Brain scans of 17 people revealed that the neurons specializing in numbers of four or less responded very specifically and selectively to their preferred number. Neurons that specialize in five through nine responded strongly not only to their preferred number, but also to numbers immediately adjacent to it.

https://www.nature.com/articles/s41562-023-01709-3.epdf?sharing_tok...

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 10:30am

Prior research has shown that exchange of material such as aerosols into the atmosphere can lead to a land-atmospheric feedback system, resulting in cooling of temperatures in a region, and subsequent changes in rainfall amounts. Likewise, irrigation efforts have been found to instigate land-atmosphere feedback as water from such systems evaporates into the atmosphere. Such systems have been found to have an impact on local hydrological cycles, and in some cases, can impact monsoon rains. These findings convinced the team on this new effort to take a closer look at the possible impact of interlinking rivers.

To estimate possible impacts, the team used causal delineation techniques along with general climate models that have been modified to focus specifically on India and its weather, and also a reanalysis of datasets built from land-atmosphere feedback systems that already exist in India.

The researchers found that land-atmosphere feedbacks from interlinked rivers could generate causal pathways between river basins in India—as one example, they found incidences of decreased rainfall in September (during monsoon season) by up to 12% in parts of the country that are already experiencing water shortages. They also found evidence of some areas experiencing more dryness during El Niño years. They conclude that more study is required before approving new river linking efforts.

Tejasvi Chauhan et al, River interlinking alters land-atmosphere feedback and changes the Indian summer monsoon, Nature Communications (2023). DOI: 10.1038/s41467-023-41668-x

Part 2

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 10:29am

Models suggest interlinking rivers in India to meet water demand may adversely impact monsoon rainfall amounts

A team of civil engineers and meteorologists at the Indian Institute of Technology, working with colleagues from the Indian Institute of Tropical Meteorology and the University of Hyderabad, has found, via modeling, that a plan to interlink rivers in India to capture rain runoff could inadvertently have a negative impact on the amount and location of monsoon rainfall.

In their study, published in the journal Nature Communications, the group used a variety of modeling techniques to test the possibility of unintended changes to weather patterns in India as interlinking projects are undertaken.

Officials in India have a clear problem on their hands—their country has a population of 1.4 billion people, the highest of any country in the world. And it is still growing. Such growth is presenting a host of problems, including how to feed so many people, sustain economic growth and manage water. This last problem has become dire—for India to feed its people, it must grow more food and that will require more water. But water availability is decreasing. To meet the demand, scientists and government officials have proposed and instigated a plan that entails digging canals between rivers to interlink them, with the idea of capturing more rainfall. Instead of allowing most of its rainfall to run off into rivers and then to the sea, the country plans to divert some of that water into other rivers that can be shunted into drier areas, where it can be used for irrigation. But doing so, the researchers on this new effort insist, could have unintended and perhaps disastrous side effects.

Part 1

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 9:55am

Vacuum cleaner-effect in fungi can hold nanoplastics at bay

Researchers have investigated the effect of tiny polystyrene particles on bacteria and fungi. While these nanoplastics reduced both bacterial and fungal growth, the fungus actually managed to "clean up" their surroundings, thereby easing the effect of the plastics. 

Nanoplastics have been proven to induce toxicity in diverse organisms, yet very little is known how this new pollutant is affecting the soil ecosystem. To study these nanoparticles of polystyrene, the researchers used microfluidic chips, a growth system that allowed them to observe interactions of single cells with the plastics under the microscope.

At the highest nanoplastics concentration, the fungi caught most of the tiny plastics present in their vicinity, in a process that  the researchers labeled the 'vacuum cleaner effect.' Overall, they found that nanoplastics can cause a direct negative effect on the soil microbes. This highlights the need for further studies that can explain how the microbial stress response might affect soil functions.

The nanoplastic particles clung to the surface of the fungal branches in such a way that the surroundings were almost nanoplastic-free. The fungus cleaned up its surroundings under high concentrations, and could then grow better again. Although the results of the study were confirmed for many conditions, the researchers point out that it might be species dependent.

This serves as a reminder to reduce our plastic waste and the pollution of soils. Finding fungi that can specifically collect nanoplastics from the soil solution may help other organisms to sustain the pollution better, and perhaps attract bacteria that can break down plastics. The fungal 'vacuum cleaner' is not an easy fix for the problem, but can give a little hope for the future.

Paola M. Mafla-Endara et al, Exposure to polystyrene nanoplastics reduces bacterial and fungal biomass in microfabricated soil models, Science of The Total Environment (2023). DOI: 10.1016/j.scitotenv.2023.166503

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 9:16am

Many midbody remnants are reabsorbed by one of the daughter cells that shed them, but those that touch down on a distant surface, like a lunar lander, may instead be absorbed by a third cell. If that cell swallows the midbody, it may mistakenly begin using the enclosed RNA as if it were its own blueprints.

Previous research showed that cancer cells are more likely than stem cells to have ingested a midbody and its potentially fate-altering cargo. Stem cells, which give rise to new cells and are valuable for their pluripotency, spit a lot of midbodies back out, perhaps to maintain their pluripotency.

Future research may be able to harness the power of midbody RNA to deliver drugs to cancer cells or to keep them from dividing.

The researchers identified a gene, called Arc, that is key to loading the midbody and midbody remnant with RNA. Taken up long ago from an ancient virus, Arc also plays a role in the way brain cells make memories.

Sungjin Park et al, The mammalian midbody and midbody remnant are assembly sites for RNA and localized translation, Developmental Cell (2023). DOI: 10.1016/j.devcel.2023.07.009

Part 2

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 9:14am

Remnant of cell division could be responsible for spreading cancer

Once thought to be the trash can of the cell, a little bubble of cellular stuff called the midbody remnant is actually packing working genetic material with the power to change the fate of other cells—including turning them into cancer.

When one cell divides into two, a process called mitosis, the result is not just the two daughter cells.

One cell divides into three things: two cells and one midbody remnant, a new signaling organelle. The midbody is full of genetic information, RNA, that doesn't have much to do with cell division at all, but likely functions in cell communication.

Researchers  analyzed the contents of midbodies—which form between the daughter cells during division—and tracked the interactions of the midbody remnants set free after cell division. Their results point to the midbody as a vehicle for the spread of cancer throughout the body.

What the researchers found inside midbodies was RNA—which is a kind of working copy of DNA used to produce the proteins that make things happen in cells—and the cellular machinery necessary to turn that RNA into proteins. The RNA in midbodies tends to be blueprints not for the cell division process but for proteins involved in activities that steer a cell's purpose, including pluripotency (the ability to develop into any of the body's many different types of cells) and oncogenesis (the formation of cancerous tumours).

A midbody remnant is very small. It's a micron in size, a millionth of a meter. But it's got everything it needs to sustain that working information from the dividing cell. And it can drift away from the site of mitosis, get into your bloodstream and land on another cell far away.

Part 1

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 8:55am

For a very long time, evolutionary biologists have tried to figure out what was behind this paradox of stasis idea," the scientists said. "What this study shows is that the answer may not be particularly complicated—we just had to conduct a study in the wild for a long enough time to figure it out."

Stroud, James T. et al, Fluctuating selection maintains distinct species phenotypes in an ecological community in the wild, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2222071120. doi.org/10.1073/pnas.2222071120

Part 3

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Firefighting Fungi
Underneath every mushroom is a sprawling, branching network of rootlike structures called a mycelium. Now researchers have successfully grown these networks into Pop Tart–size sheets that could act as a fire retardant in building materials. Mycelium contains a lot of carbon. When exposed to fire, the sheet briefly burns, releasing water and carbon dioxide into the air, before petering out and leaving behind a black layer of carbon.

Why this is so cool: Unlike asbestos, which is still sometimes added to building materials as a fire retardant, mycelium does not shed noxious compounds when exposed to fire. Mycelium could replace the fire-retardant foam that insulates many commercial buildings, which can produce carbon monoxide and other toxic products when it combusts. Mycelium is also a biological material, and any waste it leaves behind is compostable.

What the experts say: “If the product reaches the end of its life, you can just chuck that mycelium in your garden,” says Everson Kandare an engineer at RMIT University in Melbourne, Australia. “Just toss it in the green beans.”

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 8:54am

Scientists set up a field study with four different species of Anolis lizards (anoles) on a small island at the Fairchild Tropical Botanic Gardens in Coral Gables, Florida. They measured natural selection in all four lizard species over five consecutive time periods by catching and monitoring the survival of every lizard on the island.

The researchers searched day and night for lizards. Using long fishing poles with tiny lassos at their tips, they gently captured them by their strong necks, placed them in coolers, and documented the exact branch or stump where they found each lizard.

Back in the lab, they measured the lizards' heads, legs, feet, weight, and even the stickiness of their toes. After assigning an identifying number to each lizard and marking them with a tiny tag under the skin, the team released the lizards to the same branches where they'd found them. They went out in the following days and weeks to catch the rest of them.

Every six months for three years, the researchers started the process over again. Catching the same lizards, taking measurements, releasing them, and making notes of which lizards survived and which didn't.

By incorporating data for each time period, they captured the history of every lizard in the community. They then related survival data to the variation in body traits, which allowed him to analyze which body traits were important predictors of survival. Taken together, the analysis painted a picture of how natural selection operated on the community as a whole.

To his surprise, scientists found that the stabilizing form of natural selection—that which maintains a species' same, average features—was extremely rare. In fact, natural selection varied massively through time. Some years, lizards with longer legs would survive better, and other years, lizards with shorter legs fared better. For other times, there was no clear pattern at all.

The most fascinating result is that natural selection was extremely variable through time,"  the scientists said. "We often saw that selection would completely flip in direction from one year to the next. When combined into a long-term pattern, however, all this variation effectively canceled itself out: Species remained remarkably similar across the entire time period."

There had never been such insight into how selection works on a community level, and certainly not at this level of detail.

"Evolution can and does happen—it's this ongoing process, but it doesn't necessarily mean things are constantly changing in the long run," the scientists said. "Now we know that even if animals appear to be staying the same, evolution is still happening."

Understanding evolution doesn't only help us understand the plants and animals around us and how they're distributed across the world," they said. "It also shows us how life sustains itself in a world dominated by humans."

Part 2

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 8:48am

Study challenges the rules of evolutionary biology

Charles Darwin said that evolution was constantly happening, causing animals to adapt for survival. But many of his contemporaries disagreed. If evolution is always causing things to change, they asked, then how is it that two fossils from the same species, found in the same location, can look identical despite being 50 million years apart in age?

Everything changed in the past 40 years, when an explosion of evolutionary studies proved that evolution can and does occur rapidly—even from one generation to the next. Evolutionary biologists were thrilled, but the findings reinforced the same paradox: If evolution can happen so fast, then why do most species on Earth continue to appear the same for many millions of years?

This is known as the paradox of stasis and researchers set out to investigate it. 

  They conducted a long-term study in a community of lizards, measuring how evolution unfolds in the wild across multiple species. In doing so, he may have found the answer to one of evolution's greatest challenges.

The research was published as the cover story in the Proceedings of the National Academy of Sciences.

Scientists call this a paradox because it doesn't seem to make any sense. The most common explanation is that natural selection  is working to stabilize a species' appearance, with the assumption that an average form will help them survive the best. The problem is, when people do field studies, they almost never find that this kind of 'stabilizing' selection actually exists

Part 1

Comment by Dr. Krishna Kumari Challa on October 10, 2023 at 8:30am

The team tested interactions across a broad panel of 20 human and mouse cancer cell lines, ranging from Jurkat leukemia to metastatic human fibrosarcoma cells, triple-negative breast cancer and glioblastoma brain-tumor-initiating cell lines. Consistent potent cytotoxic activity was observed across the entire panel of cancer cell lines that were evaluated with portimine A. The fully synthetic portimine B was found to be substantially less effective.

Portimine A was identified as a potent inducer of apoptosis in various cancer cell lines, including MC38 cells, a colorectal carcinoma testing model. The apoptosis caused by portimine A had minimal effects on non-cancerous cells and low toxicity in mice.
Specifically, portimine A was found to target the 60S ribosomal export protein NMD3, blocking polysome formation and inhibiting protein translation and was observed to be an effective agent for suppressing tumor growth in vivo.

The exposure time to portimine A was limited by its half-life of around 30 minutes. The short duration still resulted in a significant reduction in tumor growth, indicating a very potent activity and potential therapeutic uses in the future.

Junchen Tang et al, Synthesis of portimines reveals the basis of their anti-cancer activity, Nature (2023). DOI: 10.1038/s41586-023-06535-1

The chemical synthesis and anti-cancer properties of portimines, Nature (2023). DOI: 10.1038/d41586-023-02788-y

Part 2

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