Comment

Comment by Dr. Krishna Kumari Challa on November 1, 2024 at 8:59am

Part 2

Comment by Dr. Krishna Kumari Challa on November 1, 2024 at 8:55am

Bats have acoustic cognitive maps

Echolocating bats have been found to possess an acoustic cognitive map of their home range, enabling them to navigate over kilometer-scale distances using echolocation alone.

This finding, published in Science, was demonstrated by researchers.

Would you be able to instantly recognize your location and find your way home from any random point within a three-kilometer radius, in complete darkness, with only a flashlight to guide you?

Echolocating bats face a similar challenge, with a local and directed beam of sound—their echolocation—to guide their way. Bats have long been known for their use of echolocation to avoid obstacles and orient themselves.

The researchers have now shown that bats can identify their location even after being displaced and use echolocation to perform map-based navigation over long distances.

Remarkably in experiments, even with echolocation alone, 95% of the displaced bats  returned to their roosts within minutes, demonstrating that bats can conduct kilometer-scale navigation using only this highly directional, and relatively local, mode of sensing. However, it was also shown that, when available, bats improve their navigation using vision.

The model created revealed that bats tend to fly near environmental features with higher "echoic entropy"—areas that provide richer acoustic information.

Bats can use this acoustic information to distinguish between environmental features such as a tree and a road, and thus use them as acoustic landmarks.

After being displaced, these  bats first identify their new location and then fly home, using environmental features with distinctive acoustic cues as landmarks. This behaviour suggests they possess an acoustic mental map of their home range.

Aya Goldshtein, Acoustic cognitive map-based navigation in echolocating bats, Science (2024). DOI: 10.1126/science.adn6269. www.science.org/doi/10.1126/science.adn6269

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 11:55am

Once again, tuberculosis becomes world's top infectious disease killer

In the highest tally ever recorded for tuberculosis cases, the World Health Organization report that over 8 million people worldwide were diagnosed with the lung disease last year.

Of that number, 1.25 million people died of TB, the new report found, meaning that it is once again the leading cause of deaths from infectious disease after COVID-19 displaced it briefly during the pandemic.

The fact that TB still kills and sickens so many people is an outrage, when we have the tools to prevent it, detect it and treat it," WHO Director-General Dr. Tedros Adhanom Ghebreyesus said in an agency news release. "WHO urges all countries to make good on the concrete commitments they have made to expand the use of those tools, and to end TB."

Some countries are hit harder by the disease than others. It continues to mostly affect people in Southeast Asia, Africa and the Western Pacific. India, Indonesia, China, the Philippines and Pakistan account for more than half of the world's cases, the WHO noted.

According to the report, 55% of people who developed TB were men, while 33% were women and 12% were children and young adolescents. Many new TB cases were driven by five major risk factors: undernutrition, HIV infection, alcohol use disorders, smoking [especially among men] and diabetes.

Tackling these issues, along with other social determinants such as poverty, requires a coordinated approach, the WHO added.

https://www.who.int/news/item/29-10-2024-tuberculosis-resurges-as-t...

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 11:47am

Electric fans fail to lower core body temperature of seniors during heat waves, study finds

A team of physiologists at the University of Ottawa's Human and Environmental Physiology Research Unit reports that use of an electric fan during periods of high temperatures by older people does not lower core body temperatures. In their study, published in JAMA, the group conducted experiments with elderly volunteers using fans in high-temperature conditions.

As several heat waves have struck parts of North America, high numbers of older people have died of heat stroke. This was notable due to the location of many of the deaths—the Pacific Northwest, where extremely high temperatures are rare. Because of the rarity of such high temperatures, many people in the region do not have air conditioners. Prior research has shown that older people are at higher risk of dying of heat stroke due to their lessened ability to reduce their body temperature. One notable problem is less efficient sweating.

During heat waves, officials in the affected regions suggested that older people without access to air conditioning use electric fans to stay cool. In this new effort, the research team tested the approach to see if the advice was valid.

The researchers recruited 18 people ranging in age from 65 to 72, who sat in a climate-controlled temperature chamber with an electric fan. The temperature and the fan settings were both controlled by the research team. All the volunteers were monitored during the experiments to ensure they did not become overheated.

The researchers kept the temperature inside the chamber at a steady 36°C, with a humidity level of 45%. The fans had three spin settings: off, slow and fast. All three settings were tested with the volunteers.

The researchers found that neither the slow nor the fast setting had any measurable impact on core body temperature—it was the same as if the fan was off. They also found that the slow setting did little to make the volunteers feel cooler, but the fast setting did, which, they suggest, was dangerous. Because they felt somewhat cool, the volunteers did not realize that their core body temperatures might be rising to dangerous levels.

 Fergus K. O'Connor et al, Effect of Electric Fans on Body Core Temperature in Older Adults Exposed to Extreme Indoor Heat, JAMA (2024). DOI: 10.1001/jama.2024.19457

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 11:17am

Some wildfire suppressants contain heavy metals and could contaminate the environment

In fire-prone areas, water isn't the only thing used to quell blazes. Wildland firefighters also apply chemical or synthetic suppressants. Researchers reporting in Environmental Science & Technology Letters explored whether these suppressants could be a source of elevated metal levels sometimes found in waterways after wildfires are extinguished.

Several products they investigated contained high levels of at least one metal, including chromium and cadmium, and could contribute to post-fire increases in the environment.

Wildfires are associated with the release of toxic heavy metals to the environment, but until now, it was assumed that these metals came from natural sources like soil. We now know that fire retardants may contribute to these metal releases.

Wildfire suppressant products, which are intended to inhibit fire activity before and after water evaporates, include fire retardants, water enhancers and foams. As wildfires have become more frequent and severe, larger volumes of water along with chemical and synthetic suppressants—sprayed from the ground and dropped from planes—have been required to extinguish them. Although manufacturers identify most of the active ingredients in suppressants, some components are proprietary. In addition, previous researchers have observed increased concentrations of potentially toxic metals in soil and streams after wildfires.

These results show that fire suppression activities could contribute to elevated metal levels in the environment but that more work is needed to determine potential risks to human and environmental health.

Marella H. Schammel et al, Metals in Wildfire Suppressants, Environmental Science & Technology Letters (2024). DOI: 10.1021/acs.estlett.4c00727

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:34am

Researchers show nanoplastics can reduce the effectiveness of antibiotics

In a recent study, an international research team has investigated how nanoplastic particles deposited in the body affect the effectiveness of antibiotics.

The study showed that the plastic particles not only impair the effect of the drugs, but could also promote the development of antibiotic-resistant bacteria. These results were recently published in the journal Scientific Reports.

The focus was on the broad-spectrum antibiotic tetracycline, which is used to treat many bacterial infections, such as those of the respiratory tract, skin or intestines.

When it came to plastics, the choice fell on polyethylene (PE), polypropylene (PP) and polystyrene (PS), which are ubiquitous components of packaging materials, as well as nylon 6,6 (N66), which is contained in many textiles such as clothing, carpets, sofa covers and curtains. Nanoplastics are smaller than 0.001millimeters and are considered particularly harmful to humans and the environment due to their small size.

Using complex computer models, the team was able to prove that the nanoplastic particles can bind tetracycline and thus impair the effectiveness of the antibiotic. The binding was particularly strong with nylon.

The micro- and nanoplastic load is around five times higher there than outdoors. Nylon is one of the reasons for this: it is released from textiles and enters the body via respiration, for example.

As the study results show, the binding of tetracycline to nanoplastic particles can reduce the biological activity of the antibiotic. At the same time, binding to nanoplastics could lead to the antibiotic being transported to unintended sites in the body, causing it to lose its targeted effect and possibly cause other undesirable effects.

This increase in concentration could lead to the development of antibiotic-resistant bacteria. Plastics such as nylon 6,6, but also polystyrene, which bind more strongly to tetracycline, could therefore increase the risk of resistance.

The study shows that exposure to nanoplastics is not only a direct health risk, but can also indirectly influence the treatment of diseases. If nanoplastics reduce the effectiveness of antibiotics, the dosage poses a massive problem.

Leonard Dick et al, The adsorption of drugs on nanoplastics has severe biological impact, Scientific Reports (2024). DOI: 10.1038/s41598-024-75785-4

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:26am

Comb jellies can reverse age

A new article published in Proceedings of the National Academy of Sciences reveals the unprecedented ability for reverse development in a ctenophore, also called comb jelly. The findings suggest that life cycle plasticity in animals might be more common than previously thought.

Animal life cycles typically follow a familiar pattern of decline in countless variations: they are born, grow, reproduce and die, giving way to the next generation. Only a few species are able to deviate from this general principle, the best-known example being the "immortal jellyfish" Turritopsis dohrnii, which can revert from an adult medusa back to a polyp. This elusive group of animals with flexible life cycles now includes the ctenophore Mnemiopsis leidyi.

The work challenges our understanding of early animal development and body plans, opening new avenues for the study of life cycle plasticity and rejuvenation. The fact that we have found a new species that uses this peculiar 'time-travel machine' raises fascinating questions about how spread this capacity is across the animal tree of life.

Joan J. Soto-Angel et al, Reverse development in the ctenophore Mnemiopsis leidyi, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2411499121

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:18am

It's unclear whether animals intentionally consume ethanol for ethanol's sake, and more research is needed to understand its impact on animal physiology and evolution. However, the researchers say that ethanol consumption could carry several benefits for wild animals.
First and foremost, it's a source of calories, and the odorous compounds produced during fermentation could guide animals to food sources, though the researchers say it's unlikely that animals can detect ethanol itself.

Ethanol could also have medicinal benefits: fruit flies intentionally lay their eggs in substances containing ethanol, which protects their eggs from parasites, and fruit fly larvae increase their ethanol intake when they become parasitized by wasps.

On the cognitive side, ideas have been put forward that ethanol can trigger the endorphin and dopamine system, which leads to feelings of relaxation that could have benefits in terms of sociality.

 The evolutionary ecology of ethanol, Trends in Ecology & Evolution (2024). DOI: 10.1016/j.tree.2024.09.005

Part 2

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:17am

Animal alcohol consumption more common than thought

Anecdotes abound of wildlife behaving "drunk" after eating fermented fruits, but despite this, nonhuman consumption of ethanol has been assumed to be rare and accidental. Ecologists challenge this assumption in a review published October 30 in Trends in Ecology & Evolution. They argue that since ethanol is naturally present in nearly every ecosystem, it is likely consumed on a regular basis by most fruit- and nectar-eating animals.

It is much more abundant in the natural world than we previously thought, and most animals that eat sugary fruits are going to be exposed to some level of ethanol.

Ethanol first became abundant around 100 million years ago, when flowering plants began producing sugary nectar and fruits that yeast could ferment. Now, it's present naturally in nearly every ecosystem, though concentrations are higher, and production occurs year-round in lower-latitude and humid tropical environments compared to temperate regions.

Most of the time, naturally fermented fruits only reach 1–2% alcohol by volume (ABV), but concentrations as high as 10.2% ABV have been found in over-ripe palm fruit in Panama.

Animals already harbored genes that could degrade ethanol before yeasts began producing it, but there is evidence that evolution fine-tuned this ability for mammals and birds that consume fruit and nectar. In particular, primates and tree-shrews have adapted to efficiently metabolize ethanol.

From an ecological perspective, it is not advantageous to be inebriated as you're climbing around in the trees or surrounded by predators at night—that's a recipe for not having your genes passed on.

It's the opposite of humans who want to get intoxicated but don't really want the calories—from the non-human perspective, the animals want the calories but not the inebriation.

Part 1

Comment by Dr. Krishna Kumari Challa on October 31, 2024 at 10:12am

The constraint imposed on the tissue geometry by the channel walls affects the patterns of mechanical stress experienced by the Hydra tissue, from both the hydrostatic pressure gradient across the tube and the frequent muscle contractions that take place.

The group found there was a strong preference of the body axes and the actomyosin fiber to come into alignment with the "easy-axis" of the channel, with one head and one foot along the channel axis. But different body plans developed if the initial tissue was perpendicular to the channel axis.

They wrote, "samples that are initially oriented with their primary fiber alignment perpendicular to the channel direction often regenerate into multiaxial morphologies."

But if the animals that were confined in length, perpendicular to the channel axis, they consisted mostly of animals with, amazingly, two heads, and often more than one foot. These multiple morphological features are not arranged along a single axis, but rather at junctions between axes with particular topological defects in the fiber organization.

Yonit Maroudas-Sacks et al, Confinement Modulates Axial Patterning in Regenerating Hydra, PRX Life (2024). DOI: 10.1103/PRXLife.2.043007

Part 3

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