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Comment by Dr. Krishna Kumari Challa on December 2, 2022 at 11:19am

Gut microbes influence binge-eating of sweet treats in mice

You just meant to have a single Oreo as a snack, but then you find yourself going back for another, and another, and before you know it, you have finished off the entire package even though you were not all that hungry to begin with.

But before you start feeling too guilty for your gluttony, consider this: It might not be entirely your fault. Now, new research in mice shows that specific gut bacteria may suppress binge eating behavior.

Oreos and other desserts are examples of so-called "palatable foods"—food consumed for hedonistic pleasure, not simply out of hunger or nutritional need. Humans are not alone in enjoying this kind of hedonism: Mice like to eat dessert, too. Even when they have just eaten, they will still consume sugary snacks if available.

The new  study shows that the absence of certain gut bacteria causes mice to binge eat palatable foods: Mice with microbiotas disrupted by oral antibiotics consumed 50 percent more sugar pellets over two hours than mice with gut bacteria. When their microbiotas were restored through fecal transplants, the mice returned to normal feeding behavior. Further, not all bacteria in the gut are able to suppress hedonic feeding, but rather specific species appear to alter the behavior. Bingeing only applies to palatable foods; mice with or without gut microbiota both still eat the same amount of their regular diet. The findings show that the gut microbiota has important influences on behavior and that these effects can be modulated when the microbiota is manipulated.

https://www.cell.com/current-biology/fulltext/S0960-9822(22)01750-X

Comment by Dr. Krishna Kumari Challa on December 2, 2022 at 11:11am

To track disease-carrying mosquitoes, researchers tag them with DNA barcodes

West Nile, Zika, dengue and malaria are all diseases spread by bites from infected mosquitoes. To track the threat of such diseases over large populations, scientists need to know where the mosquitoes are, where they've been, and where they might go.

But  tracking mosquitoes is no easy task. The capture, tagging and release of single mosquitoes—as is commonly done with bats and other disease carriers—would be ridiculous, if not impossible. A common mosquito-tracking technique involves dousing the insects in fluorescent powder and letting them fly away, but the practice is error-prone and unreliable.

So scientists are now introducing a better way to perform mosquito-tracking for disease applications. Their new method, which involves getting larval mosquitoes to eat harmless particles made entirely of DNA and proteins, has the potential to revolutionize how people study mosquito-borne diseases.

The edible mosquito marker particles are porous protein crystals that self-assemble from a protein originally found in Camplyobacter jejuni bacteria. Since inventing these very small, non-toxic protein crystals that feature highly precise arrays of pores, researchers have been exploring diverse applications for them, like capturing virus particles to facilitate wastewater testing. They discovered they could insert fluorescent dyes or synthetic DNA into their crystals very easily, and the DNA wouldn't budge even after multiple washes and exposure to solvents.

They also performed a series of experiments that demonstrate the utility of these barcodes as tags capable of labeling millions of individual mosquitoes. So far, results are promising.

Here's how they do it: mosquito larvae ingest tasty biomass that's pre-loaded with the DNA crystals in solution. As the mosquitoes grow into adults, the DNA crystals remain intact in their guts, creating a code that can be later read through laboratory techniques like quantitative polymerase chain reaction.

The method the researchers are demonstrating is unique in one important way: Unlike conventional mosquito-tagging in which adult mosquitoes are extracted from traps and analyzed for disease, the DNA barcodes are ingested by the mosquitoes in their larval states, persisting with them as they become adults. In this way, researchers can not only track where the mosquitoes ended up, but where they started, and how they moved. Such insights could prove critical for disease-surveillance applications in the future.

Julius D Stuart, Daniel A Hartman, Lyndsey I Gray, Alec A Jones, Natalie R Wickenkamp, Christine Hirt, Aya Safira, April R Regas, Therese M Kondash, Margaret L Yates, Sergei Driga, Christopher D Snow, Rebekah C Kading. Mosquito tagging using DNA-barcoded nanoporous protein microcrystals. PNAS Nexus, 2022; 1 (4) DOI: 10.1093/pnasnexus/pgac190

Comment by Dr. Krishna Kumari Challa on December 2, 2022 at 8:52am

Mom's dietary fat rewires male and female brains differently

More than half of all women in the United States are overweight or obese when they become pregnant. While being or becoming overweight during pregnancy can have potential health risks for moms, there are also hints that it may tip the scales for their kids to develop psychiatric disorders like autism or depression, which often affects one gender more than the other.

What hasn’t been understood however is how the accumulation of fat tissue in mom might signal through the placenta in a sex-specific way and rearrange the developing offspring’s brain.

To fill this gap researchers studied pregnant mice on a high-fat diet. In findings appearing November 28 in the journal Nature Metabolism, they found that mom’s high-fat diet triggers immune cells in the developing brains of male but not female mouse pups to overconsume the mood-influencing brain chemical serotonin, leading to depressed-like behaviour.

The researchers said a similar thing may be happening in humans, too.

They are now starting to work out how and why female offspring are impacted differently when mom amasses high levels of fat during pregnancy. Fat doesn’t lead to depression in female mice, but it does make them less social, perhaps due to an overconsumption of the pro-social hormone oxytocin, instead of serotonin.

For now, this research highlights that not all placentas are created equally. This work may one day help guide clinicians and parents in better understanding and possible treatment or prevention of the origins of some mood disorders by considering early environmental factors, like fat accumulation during gestation.

“Maternal Diet Disrupts the Placenta-Brain Axis in a Sex-Specific Manner,” Alexis M. Ceasrine, Benjamin A. Devlin, Jessica L. Bolton, Lauren A. Green, Young Chan Jo, Carolyn Huynh, Bailey Patrick, Kamryn Washington, Cristina L. Sanchez, Faith Joo, A. Brayan Campos-Salazar, Elana R. Lockshin, Cynthia Kuhn, Susan K. Murphy, Leigh Ann Simmons, Staci D. Bilbo. Nature Metabolism, Nov. 28, 2022. DOI: 10.1038/s42255-022-00693-8

Comment by Dr. Krishna Kumari Challa on December 2, 2022 at 8:34am

A targeted approach to reducing the health impacts of crop residue burning in India

To clear the way for planting wheat in November, a farmer in Punjab, India, sets aflame the leftover straw, or stubble, of a harvested rice paddy crop in October. The burning residue fills the air with carbon monoxide, ozone, and fine particulate matter (PM_2.5) that will make it harder to breathe for days afterward and for miles around. It's a scene that's replicated on about 2 million farms in the Punjab and Haryana states of northwest India every autumn (and every spring after the wheat harvest), raising health risks—particularly of respiratory and cardiovascular diseases—and premature death rates downwind in India and throughout South Asia.

To date, government regulations, largely imposed at the state and national level, have been ineffective in curtailing crop residue burning in India. The practice continues apace, driven by the limited economic value of rice and wheat residues, and the ongoing need for cheap, ultrafast disposal of residues between harvesting and planting of the rotating crops. Such attempted bans are also deeply unpopular. A national ban on burning was repealed last year due to pressure from farmers, who see such legislation as further increasing the already-significant economic hardships faced by small-scale landowners.

In search of more effective solutions, a team of researchers at MIT and Harvard University estimated which burning events, in what locations and at what times, produced the greatest increases in population exposure, premature deaths, and economic losses in India during the years 2003–09. Then they quantified how small-scale and targeted actions could reduce air pollution and health risks for the entire population. Their findings appear in the journal Nature Communications.

Based on computer models of the seven-year study period, the researchers attributed between 44,000 and 98,000 PM_2.5-exposure-related premature deaths annually to crop residue burning, with 67–90% occurring as a result of burning that took place in the Punjab, Haryana, and Uttar Pradesh states. They also found that six districts within Punjab—each with relatively high cultivation of residue-intensive crops and downwind population density—contributed 40% of India's annual air-quality impacts from the practice.

The research team next identified several opportunities to reduce crop residue burning and its attendant health effects. First, if farmers in Punjab were to burn crop residues two hours earlier in the day, they could avert up to 14% of air-quality impacts and about 10,000 deaths each year. They could achieve further reductions by adopting rice varieties such as basmati that require less residue burning. Finally, such targeted actions could achieve most of their benefits if adopted in just a few regions, given the large contribution from the aforementioned six districts in Punjab.

Ruoyu Lan et al, Air quality impacts of crop residue burning in India and mitigation alternatives, Nature Communications (2022). DOI: 10.1038/s41467-022-34093-z

Comment by Dr. Krishna Kumari Challa on November 30, 2022 at 10:40am

Time slows down on crowded train!

Testing time perception in an unusually lifelike setting—a virtual reality ride on a New York City subway train—an interdisciplinary Cornell research team found that crowding makes time seem to pass more slowly.

As a result, rush-hour commutes on public transit may feel significantly longer than other rides that objectively take the same amount of time.

The research adds to evidence that social context and subjective feelings distort our sense of the passage of time, and may have practical implications for people's willingness to use public transit, particularly after the pandemic.

It's a new way of thinking about social crowding, showing that it changes how we perceive time. Crowding creates stressful feelings, and that makes a trip feel longer.

: Saeedeh Sadeghi et al, Affective experience in a virtual crowd regulates perceived travel time, Virtual Reality (2022). DOI: 10.1007/s10055-022-00713-8 Saeedeh

Saeedeh Sadeghi et al, Crowding and Perceived Travel Time in Public Transit: Virtual Reality Compared With Stated Choice Surveys, Transportation Research Record: Journal of the Transportation Research Board (2022). DOI: 10.1177/03611981221130346

Comment by Dr. Krishna Kumari Challa on November 30, 2022 at 10:00am

The effects of climate change on body size evolution

The Northern Treeshrew, a small, bushy-tailed mammal native to South and Southeast Asia, defies two of the most widely tested ecological "rules" of body size variation within species, according to a new study.

The unexpected finding, researchers say, may be attributable to climate change—the body size rules reversed in Northern Treeshrews as average temperatures climbed—and likely exists in other species.

The first-of-its-kind study, published Nov. 29 in the journal Scientific Reports, found that the Northern Treeshrew (Tupaia belangeri) breaks both Bergmann's rule and the island rule. The former describes a common pattern wherein individuals of a warm-blooded species inhabiting colder climates—generally located at higher latitudes—have larger average body sizes than those in warmer climates, which are usually at lower latitudes. The latter predicts that small mammal species evolve larger body sizes on islands than their mainland counterparts, whereas island-bound large mammals evolve smaller body sizes.

Although both rules have been repeatedly tested from a strictly geographic standpoint, how they interact—and possibly even change over shorter timescales amidst rapid climate change—has never been rigorously examined.

In the first published study to do so, researchers analyzed 839 museum specimens of adult Northern Treeshrews collected over 130 years from across their entire geographic range, including mainland and island populations, along with historical climate data.

They found that, contrary to Bergmann's rule, body size of the Northern Treeshrew increased in warmer climates closer to the equator. More importantly—and quite unexpectedly—they discovered that both rules have reversed over a remarkably brief period between the late 19th and 20th centuries, with the reversal accelerating as average temperatures rose.

This study highlights that body size is linked to complex, dynamic and potentially interdependent ecological factors. This is the first time a rule reversal like this has been found in any species. The study also found that the two rules are intertwined. 

Maya M. Juman et al, Recent and rapid ecogeographical rule reversals in Northern Treeshrews, Scientific Reports (2022). DOI: 10.1038/s41598-022-23774-w

Comment by Dr. Krishna Kumari Challa on November 30, 2022 at 8:56am

A secret of developing life: In some instances the fetus helps repair a ruptured amniotic sac

Premature rupture of the amniotic sac can have devastating consequences, but scientists are studying instances when the damaged sac repairs itself—a phenomenon that requires cooperation of the developing fetus.

A new investigation of the amnion, the innermost layer of epithelial cells in the amniotic sac reveals a cascade of cellular events that result in sac repair. The new research helps lay the groundwork for a keener understanding of both healthy pregnancies and when things go awry.

Aware that premature rupture of the amniotic membranes can lead to premature birth, researchers are asking what causes the sac to reseal. Producing a definitive answer to that question may ultimately lead to interventions that prevent premature birth for those whose membranes don't reseal. The biggest potential benefit down the road is guarding against the sometimes lethal outcomes when babies are born too small, too soon.

The premature rupture of the amniotic sac, a condition referred to as a preterm prelabour rupture of membranes (pPROM) is a leading cause of preterm birth. In some cases, these ruptured membranes heal spontaneously. Researchers investigated repair mechanisms of the amnion, a layer of epithelial cells in the amniotic sac closest to the fetus.

Amniotic membranes normally remain intact until the onset of active labor or within 24 hours before labor starts. pPROM may not be easy to detect. For some women, fluid leaks slowly and may be mistaken for urine. Obstetricians say it's important to note that amniotic fluid usually has no color and doesn't smell like urine. They also underscore that premature membrane rupture can occur for a variety of reasons.

In some women the amnion can rupture early for reasons ranging from infections of the uterus, cervix, or vagina to too much stretching of the amniotic sac. The latter may occur as a direct result of too much fluid in the sac, or more than one baby putting pressure on the membranes. Other causes of membrane rupture include conditions such as malnutrition, or intrauterine bleeding. Smoking is another factor that can cause rupture.

In this new study the research  team found that fetal macrophages are recruited to rupture sites in both the human and mouse amnion and assist in the repair of torn membranes.

Macrophages migrated to and resided at rupture sites in both human and mouse amnion. A process called epithelial-mesenchymal transition,  in which epithelial cells acquire a mesenchymal phenotype and which is implicated in tissue repair, was observed at rupture sites.

In short, epithelial cells took on the role of mesenchymal cells and helped begin the process of resealing. None of the cascade of biological events would have occurred without macrophages first migrating to and taking up residence at the rupture site. This shows that ruptures are reversible with repairs

The membrane repair is highly reliant on signaling molecules: in this case, transformation growth factor-β/Smad—TGF-β/Smad—signaling. TGF-β/Smad was prominent in both mouse and human samples. 

This  study's findings could potentially inform research into treatments for preterm membrane ruptures to prevent preterm birth.

Yosuke Kawamura et al, Fetal macrophages assist in the repair of ruptured amnion through the induction of epithelial-mesenchymal transition, Science Signaling (2022). DOI: 10.1126/scisignal.abi5453

Comment by Dr. Krishna Kumari Challa on November 30, 2022 at 8:45am

Blood Thinner Ineffective for COVID-19 Patients: Study

A clinical trial finds that the anticoagulant apixaban, which has been prescribed to help COVID-19 patients recover, is ineffective and in rare instances dangerous.

N

ew data from a clinical trial suggest that apixaban, an anticoagulant that’s widely been prescribed to promote recovery in patients with severe cases of COVID-19, doesn’t offer any discernable benefit for people with the disease.

The UK-wide trial, which is run by Addenbrooke’s Hospital and the University of Cambridge, involved more than 1,000 hospitalized COVID-19 patients and compared the outcomes of those who had been randomly assigned to receive apixaban to those who had not, according to Financial Times. It found that 29.1 percent of those who received the blood thinner either ended up back in the hospital or died within a year, compared to 30.8 percent of people who weren’t given the drug. That finding doesn’t support apixaban as an effective treatment for COVID-19, and the researchers conclude that doctors ought to stop prescribing it to their coronavirus patients. Meanwhile, BBC News reports that a “small number” of the 402 patients who took apixaban had to discontinue treatment due to severe bleeding.

The trial will continue with other drugs thought to help against COVID-19, according to BBC News, including a statin called atorvastatin that may help lessen the inflammatory response launched by COVID-19 patients’ immune systems and so prevent tissue damage.

https://clinicaltrials.gov/ct2/show/NCT04801940

https://www.the-scientist.com/news-opinion/blood-thinner-ineffectiv...

Comment by Dr. Krishna Kumari Challa on November 29, 2022 at 8:57am

The largest source of abiotic methane gas on Earth

Methane (CH₄), the chief constituent of natural gas, is one of the most widely used "clean" fuels. Although methane is usually considered to originate from organic matter, recently, more and more evidence shows that methane can be produced by abiotic processes.

Researchers demonstrated that large amounts of methane gas can form during prograde metamorphism in a cold subduction zone, evidenced by the massive CH₄-rich fluid inclusions in eclogites from Western Tianshan, China.

Based on their calculation, the potential CH₄ flux from worldwide modern subduction zones is estimated to be as much as ~10.8 Mt/y. Consequently, the subducted cold oceanic crust may produce the largest amount of abiotic methane, along with other abiotic methane sources such as that from mid-ocean ridges or that from by high-pressure serpentinization.

Massive CH₄-rich fluid inclusions have been found in garnet and omphcite, which are the main constituent minerals of eclogite in the West Tianshan subduction zone (eclogite is the most important high grade metamorphic rock during cold subduction). Isotopic analyses and petrological studies both demonstrated that this methane was of abiotic origin and formed by water-rocks reactions during the prograde high-pressure to ultrahigh-pressure metamorphism.

 Lijuan Zhang et al, Massive abiotic methane production in eclogite during cold subduction, National Science Review (2022). DOI: 10.1093/nsr/nwac207

Comment by Dr. Krishna Kumari Challa on November 29, 2022 at 8:51am

New kind of tropical cyclone identified in the Indian Ocean

Oceanography experts have described a new kind of cyclone in the Indian Ocean near Sumatra after observing satellite surface winds in the region.

The experts' search for the trigger mechanisms of the Indian Ocean Dipole has led to the discovery of the new type of atmospheric tropical cyclone forming in the South-East Tropical Indian Ocean (SETIO) that they call SETIO Cyclone.

The Indian Ocean Dipole (IOD) is a coupled atmosphere-ocean interaction in the tropical Indian Ocean that strongly affects the climate and rainfall variability of surrounding countries including Australia.

Researchers  found that SETIO cyclones are short-lived weather-like events that develop frequently during austral winter/spring and operate to maintain a warm surface ocean in the region.

Dramatic changes happen in some years when SETIO cyclones fail to develop, and ambient winds trigger the appearance of cold seawater in a vast area strongly disturbing both winds and rainfall patterns over the Indian Ocean.

In the natural sciences, it is of uttermost importance to identify so-called trigger processes, such as SETIO cyclones, that link the cause to an effect.

This is a rare new discovery that sheds new light into the functioning of the IOD.

Ankit Kavi et al, Synoptic-scale atmospheric cyclones in the South-East Tropical Indian Ocean (SETIO) and their relation to IOD variability, Journal of Southern Hemisphere Earth Systems Science (2022). DOI: 10.1071/ES22020

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