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Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 11:03am

Humans have trichromatic vision with three photoreceptors, where every color perceived can be made from a combination of red, green and blue. Butterflies, however, have compound eyes, with six (or more) photoreceptor classes with distinct spectral sensitivities. In particular, the Papilio xuthus, a yellow, Asian swallowtail butterfly, has not only blue, green and red, but also violet, ultraviolet and broadband receptors. Further, butterflies have fluorescent pigments that allow them to convert UV light into visible light which can then be easily sensed by their photoreceptors. This allows them to perceive a broader range of colors and details in their environment.

Beyond the increased number of photoreceptors, butterflies also exhibit a unique tiered structure in their photoreceptors. To replicate the UV sensing mechanism of the Papilio xuthus butterfly, the UIUC team has emulated the process by combining a thin layer of PNCs with a tiered array of silicon photodiodes.

PNCs are a class of semiconductor nanocrystals that display unique properties similar to that of quantum dots—changing the size and composition of the particle changes the absorption and emission properties of the material. In the last few years, PNCs have emerged as an interesting material for different sensing applications, such as solar cells and LEDs. PNCs are extremely good at detecting UV (and even lower) wavelengths that traditional silicon detectors are not. In the new imaging sensor, the PNC layer is able to absorb UV photons and re-emit light in the visible (green) spectrum which is then detected by the tiered silicon photodiodes. Processing of these signals allows for mapping and identification of UV signatures.

Part 2

Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 11:03am

Seeing the unseen: How butterflies can help scientists detect cancer

There are many creatures on our planet with more advanced senses than humans. Turtles can sense Earth's magnetic field. Mantis shrimp can detect polarized light. Elephants can hear much lower frequencies than humans can. Butterflies can perceive a broader range of colors, including ultraviolet (UV) light.

Inspired by the enhanced visual system of the Papilio xuthus butterfly, a team of researchers have developed an imaging sensor capable of "seeing" into the UV range inaccessible to human eyes. The design of the sensor uses stacked photodiodes and perovskite nanocrystals (PNCs) capable of imaging different wavelengths in the UV range. Using the spectral signatures of biomedical markers, such as amino acids, this new imaging technology is even capable of differentiating between cancer cells and normal cells with 99% confidence.

Researchers have taken inspiration from the visual system of butterflies, who are able to perceive multiple regions in the UV spectrum, and designed a camera that replicates that functionality. They did this by using novel perovskite nanocrystals, combined with silicon imaging technology, and this new camera technology can detect multiple UV regions.

UV light is electromagnetic radiation with wavelengths shorter than that of  visible light(but longer than X-rays). We are most familiar with UV radiation from the sun and the dangers it poses to human health. UV light is categorized into three different regions—UVA, UVB and UVC— based on different wavelength ranges. Because humans cannot see UV light, it is challenging to capture UV information, especially discerning the small differences between each region.

Butterflies, however, can see these small variations in the UV spectrum, like humans can see shades of blue and green.UV light is incredibly difficult to capture, it just gets absorbed by everything, and butterflies have managed to do it extremely well.

Part 1

Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 9:34am

Researchers find evidence of mpox circulating in humans since 2016

A large international team of medical researchers and epidemiologists has found evidence that monkeypox (mpox) has been circulating in humans since 2016. In their study, reported in the journal Science, the group used Bayesian evolutionary analysis of the mpox virus to show that its genomic history includes years of change due to human infections.

Mpox was first identified in the 1950s after an illness struck a group of research monkeys in Denmark. Twenty years later, the first case was detected in a human in Africa. Over the following decades, several cases of the disease were seen in humans and all were attributed to the virus jumping from other mammals.

Then, in 2017, an outbreak occurred in Nigeria and by 2022, it had spread across the globe, demonstrating that the virus had evolved to jump from human to human. In this new effort, the research team took a closer look at the genome of the virus behind mpox to learn more about its evolutionary history, particularly how it relates to human infections. The researchers sequenced the genome of the mpox virus to learn more about its evolutionary history. They found that the clade IIb was the one that had spread around the world. They also noted that it looked different from other strains that had been seen before in Africa.

They found a mutation that had led to the production of an enzyme called APOBEC3, which was found to cause further mutations that alter genome base pairs. It was also found to have come about due to infections in humans. That allowed the team to trace the evolutionary history of the virus as it infected humans—they found such mutations going back to approximately 2016, which strongly suggests that the virus has been transmittable between humans since that year. The research team concludes that there is a strong likelihood of multiple cases of small mpox outbreaks that have not been recognized, allowing the virus to spread under the radar. They further suggest stronger surveillance methods be established because the virus is still mutating rapidly and could become deadlier.

Áine O'Toole et al, APOBEC3 deaminase editing in mpox virus as evidence for sustained human transmission since at least 2016, Science (2023). DOI: 10.1126/science.adg8116

Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 9:29am

If the sensors succeed in more extensive trials, the scientists said, the possible applications for spaceflight are many—from helping astronauts land safely on the surface of a planet, to supporting them as they move outside a vehicle in space.

Vibrotactile Feedback as a Countermeasure for Spatial Disorientation, Frontiers in Physiology (2023). DOI: 10.3389/fphys.2023.1249962
Part 3
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Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 9:28am

The researchers used sensory deprivation and a multi-axis rotation device to test their vibrotactors in simulated spaceflight, so the senses participants would normally rely on were useless. Could the vibrotactors correct the misleading cues the participants would receive from their vestibular systems, and could participants be trained to trust them?

In total, 30 participants were recruited, of whom 10 received training to balance in the rotation device, 10 received the vibrotactors, and the remaining 10 received both. All participants were shown a video of the rotation device and told how it worked: moving like an inverted pendulum until it reached a crash boundary, unless it was stabilized by a person sitting in the device controlling it with a joystick.

Additional training, for the participants who received it, included tasks that taught participants to disengage from their vestibular sense and rely on the vibrotactors instead of their natural gravitational cues. These tasks involved searching for hidden non-upright balance points, which meant participants had to ignore their desire to align to upright and focus on the vibrotactors.

All participants were given a blindfold, earplugs, and white noise to listen to. Those with vibrotactors had four strapped to each arm, which would buzz when they moved away from the balance point. Each participant took part in 40 trials, aiming to keep the rotation device as close to the balance point as possible.

For half the trials, the rotation device operated on a vertical roll plane. This was considered an Earth analog because participants could use their natural gravitational cues for orientation. During the second half, which acted as a spaceflight analog, the rotation device operated on a horizontal roll plane where those gravitational cues could no longer help.

After each block of trials, participants were asked to rate how disoriented they felt and how much they trusted the vibrotactors. The scientists measured their success by looking at how often they crashed and how well they controlled their balance.
All the groups were initially disoriented in the spaceflight analog. The scientists expected this, because participants could not rely on the natural gravitational cues that they usually use. Nearly all participants reported that they trusted the vibrotactors, but they also reported confusion from conflicts between their internal cues and the vibrotactors.

The participants wearing vibrotactors still performed better than those who only received training. The training-only group crashed more frequently, moved around the balance point more, and accidentally destabilized themselves more often. Receiving the training did help, though. As the trials continued, the group who received both training and vibrotactors performed best.

However, even with training, the participants didn't perform as well as they did in the Earth analog. They may have needed more time to integrate cues from the vibrotactors, or the buzzing from the vibrotactors may not have given a strong enough danger signal.

"A pilot's cognitive trust in this external device will most likely not be enough" . "Instead, the trust has to be at a deeper—almost sub-cognitive—level. To achieve this, specialized training will be required."
Part 2

Comment by Dr. Krishna Kumari Challa on November 4, 2023 at 9:27am

Wearable devices may prevent astronauts getting 'lost' in space

Taking space  flight is dangerous. In leaving the Earth's surface, we lose many of the cues we need to orient ourselves, and that spatial disorientation can be deadly. Astronauts normally need intensive training to protect against it. But scientists have now found that wearable devices which vibrate to give orientation cues may boost the efficacy of this training significantly, making spaceflight slightly safer.

Long-duration spaceflight will cause many physiological and psychological stressors, which will make astronauts very susceptible to spatial disorientation. When disoriented, an astronaut will no longer be able to rely on their own internal sensors, which they have depended on for their whole lives.
Part 1

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:35am

Neurons in the brain stop working very quickly if you deprive them of oxygen or glucose. If you add oxygen again, they’ll simply resume their work and do so just as quickly.

To better understand what happens inside the brain during syncope, the researchers used electrodes to record the activity of thousands of neurons from various brain regions in mice as the animals fainted. Activity decreased in all areas of the brain, except one specific region of the hypothalamus known as the periventricular zone (PVZ).

The authors then blocked the activity of the periventricular zone, and the mice experienced longer fainting episodes. Stimulating the region caused the animals to wake up and start moving again. The team suggests that a coordinated neural network that includes NPY2R VSNs and the PVZ regulates fainting and recovery.

Lovelace, J. W. et al. Nature https://doi.org/10.1038/s41586-023-06680-7 (2023).

https://www.nature.com/articles/s41586-023-06680-7.epdf?sharing_tok...

Part 3

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Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:33am

What causes fainting? Scientists finally have an answer

Mouse experiments reveal the brain–heart connections that cause us to lose consciousness rapidly — and wake up moments later.

Whether as a result of heat, hunger, standing for too long or merely the sight of blood or needles, 40% of people faint at least once in their lives.

But exactly what causes these brief losses of consciousness — which researchers call syncope — has been a mystery..

Now, researchers have discovered a neural pathway that controls the process, involving a group of sensory neurons that connect the heart to the brainstem. A study published in Nature on 1 November reports that activating these neurons made mice stop moving and fall over almost immediately, then display symptoms observed during human syncope, such as rapid pupil dilation and rolling eyes.

The authors suggest that this pathway holds the key to understanding fainting, beyond the long-standing observation that it results from reduced blood flow in the brain. There is blood-flow reduction, but, at the same time, there are dedicated circuits in the brain which manipulate this.

Using single-cell RNA sequencing analysis of the nodose ganglion, part of the vagus nerve (which connects the brain to several organs, including the heart), the team identified sensory neurons that express a type of receptor involved in the contraction of small muscles in blood vessels.

These neurons, called NPY2R VSNs, are distinct from other branches of the vagus nerve that connect to the lungs or the gut. Instead, they form branches in the lower, muscular parts of the heart, called the ventricles, and connect to a distinct area of the brainstem called the area postrema.

By combining high-resolution ultrasound imaging with optogenetics — a way of controlling neuronal activity using light — the researchers stimulated the NPY2R VSNs in mice while monitoring the animals’ heart rate, blood pressure, respiration and eye movements. This allowed the team to manipulate specific neurons and visualize the heart in real time.

When the NPY2R VSNs were activated, mice that had been moving around freely fainted in a few seconds. As well as showing rapid pupil dilation and eyes rolling back in their sockets, the mice demonstrated other symptoms of syncope in humans, including reduced heart rate, blood pressure, breathing rate and blood flow to the brain.

Humans usually recover rapidly from syncope. 

Part 2

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 9:29am

.

Mysteries of fainting revealed Experiments in mice have identified a specific group of sensory neurons that is responsible for syncope, the brief loss of consciousness during fainting. The cells — called NPY2R vagal sensory neurons — are found in the vagus nerve, which connects the brain to the heart and other organs. Scientists activated these cells in mice that were roaming about, which then fainted within a few seconds. Their pupils dilated, their eyes rolled back and their heart rate, blood pressure and breathing rate all dipped. The team also found that a region of the brain’s hypothalamus is responsible for recovery from fainting.
Part 1

Comment by Dr. Krishna Kumari Challa on November 3, 2023 at 8:56am

Wildfire plumes deposit ash on seawater, fueling growth of phytoplankton

A team of marine biologists has found that large wildfires can deposit large amounts of ash on seawater, fueling the growth of phytoplankton. In their study, reported in the journal Proceedings of the Royal Society B: Biological Sciences, the group tested the impact of ash from a major wildfire on seawater samples in their lab.

Prior research has shown that large forest fires and wildfires produce a large amount of ash that remains in the air for a period of time before falling. Prior research has also found that when ash falls onto land, the result is usually positive—the ash serves as a form of fertilizer. Unfortunately, the same cannot be said for rivers and lakes—the sudden infusion of large amounts of toxic metals can kill fish and other aquatic creatures such as mollusks. For larger bodies of water, it can lead to algal blooms that remove oxygen from the water, resulting in dead zones. For this new study, the research team tracked wildfire plumes over the ocean. They collected samples of ash generated by the Thomas Fire in 2017 and brought them back to their lab for testing. The team mixed samples with fresh seawater in a jar. After a few days, they found that the ash/water solution contained high levels of dissolved nutrients, such as nitrogen and silicic acid. They found it also contained high levels of metals. The researchers then added more seawater to their ash/water solution that also contained microorganisms native to the ocean. They found that after several days, the number of microorganisms was twice as high as it was in a control sample of seawater. They also noted that they did not find any evidence that the ash had a toxic impact on the sea microorganisms. They suggest their work implies that wildfire plumes that settle on the ocean surface can lead to growth of phytoplankton communities.

T. M. Ladd et al, Food for all? Wildfire ash fuels growth of diverse eukaryotic plankton, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.1817

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