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Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 12:52pm

New Paper Links Climate Change to Shrinking Brain Size in Humans

A new study suggests a link between past climate changes and a drop in the size of the human brain – an adaptive response that emerges in an analysis of climate records and human remains over a 50,000-year period.

The study looked at how the brain size of 298 Homo specimens changed over the last 50,000 years in relation to natural records of global temperature, humidity, and rainfall. When the climate got warmer, the average brain size grew significantly smaller than when it was cooler.

researchers obtained data on skull sizes from ten separate published sources, for a total of 373 measurements from 298 human bones spanning 50,000 years. He included body size estimations that were adjusted for geographical region and gender to estimate brain sizes.

The fossils were put into groups based on how long ago they lived, and scientists conducted this research using four different fossil age spans of 100 years, 5,000 years, 10,000 years, and 15,000 years to help account for dating errors.

Then they compared brain size to four climate records, including temperature data from European Project for Ice Coring in Antarctica (EPICA) Dome C. The ice core at EPICA Dome C gives accurate measurements of the surface temperature going back more than 800,000 years.

The analysis showed a general pattern of changing brain size in Homo, which is correlated with climate change as temperatures rise and fall. Humans had a considerable decline in average brain size, amounting to just over 10.7 percent, throughout the Holocene warming period.

"Brain size changes appear to take place thousands of years after changes to climate, and this is particularly pronounced after the last glacial maximum, approximately 17,000 years.

While [acclimatization] unfolds within a single generation and natural selection can happen in as short as a few successive generations, species level adaptation often takes many successive generations."

This evolutionary pattern happened over a relatively brief period of time, ranging from 5,000 to 17,000 years, and the trends suggest that ongoing global warming could have detrimental effects on human cognition.

"Even a slight reduction in brain size across extant humans could materially impact our physiology in a manner that is not fully understood.

The analysis showed that humidity and rainfall levels also had an effect on brain growth. While temperature is a more significant factor, it did find a weak correlation between dry spells and slightly larger brain volumes.

 ecosystem factors like predation, indirect climate effects like vegetation and net primary production, or non-climate factors like culture and technology could all be contributing to changes in brain size.

"The results suggest that climate change is predictive of Homo brain size, and certain evolutionary changes to the brain may be a response to environmental stress.

Part 1

Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 12:47pm

The researchers also want to look into whether this new type of cell is present in the embryos of other primates besides humans. Based on the limited number of studies currently available, it seems likely that it is – a recent study suggests the same sort of activity could be happening in monkey embryos.

Jumping genes stay with us for our whole lives, and our bodies have to be continually on alert to make sure they're tightly managed. What this new research suggests is that in the earliest stages of life, they're more influential than we realized.

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pb...

Part 2

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Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 12:46pm

Scientists Discover a Self-Destructing Cell That Shields a Growing Embryo

Scientists have found a new human embryonic cell type, one that seems designed to protect the growing embryo by acting as a quality control measure and making sure that damaged cells are removed.

There's still a lot we don't know about the earliest stages of embryo formation, and this latest discovery promises to help future research into ensuring that pregnancies are given the best chance of success.

While we're all made up of trillions of cells as adults, life begins as a single cell that then divides again and again. As this division continues, cells start to specialize in their function – but in a genetic activity analysis of 5-day old embryos, researchers found certain cells that didn't match the standard profiles.

What makes these cells interesting is that they contain active 'jumping genes' (or transposons), rogue bits of DNA that can copy themselves, move around, and insert themselves back into the genome, potentially causing damage along the way. However, it seems that when this damage occurs, the newly discovered cells then self-destruct.

"If a cell is damaged by the jumping genes – or any other sort of error such as having too few or too many chromosomes – then the embryo is better off removing these cells and not allowing them to become part of the developing baby.

In other words, these new cells are deliberately configured to lose out in a survival of the fittest battle, sacrificing themselves to give the healthier cells priority and the embryo a better chance of growing.

These new cells have been called REject cells, because they're ultimately rejected and because they feature RetroElements, a specific type of jumping gene. Around a quarter of the cells are REject cells five days after fertilization, the study reveals.

The cells that are left behind are able to suppress their active jumping genes and don't have the same self-destruction routines built into them, the researchers found. Finding out exactly why this is and what's going on can be tackled in future studies.

"We are used to the idea of natural selection favoring one organism over another. What we are seeing within embryos also looks like survival of the fittest but this time between almost identical cells."

The researchers suggests that one difference between a successful and unsuccessful pregnancy might be how these REject cells behave, or how sensitive the embryo is to their messaging.

Part 1

Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 12:00pm

Money key for turning preprints into papers

Only 40% of preprints by researchers in lower-income countries will even..., compared with 61% authored by researchers in high-income nations. An analysis of almost 140,000 papers posted on the preprint servers bioRxiv and medRxiv between their inception (in 2013 and 2019, respectively) and 2021 also found that when a researcher in a richer country was added to the author list, the preprint-to-paper conversion rate increased. A lack of financial resources in poorer regions is likely to be one of the key factors preventing the transition from preprint to paper.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0...

Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 11:42am

The study looked at observational and climate model data between 1960 and 2014, and then at projections for 2045 to 2099.

Researchers first looked at the impact of the jet stream—the air currents that drive weather patterns in many of the world's most important crop producing regions.

They found that a "strong meandering" of the jet stream, flowing in big wave shapes, has particularly significant impacts on key agricultural regions in North America, Eastern Europe and East Asia, with a reduction in harvests of up to seven percent.

The researchers also found that this had been linked to simultaneous crop failures in the past.

One example was in 2010, when the fluctuations of the jet stream were linked to both extreme heat in parts of Russia and devastating floods in Pakistan, which both hurt crops.

The study also looked at how well computer models assess these risks and found that while they are good at showing the atmospheric movement of the jet stream, they underestimate the magnitude of the extremes this produces on the ground.

 Kai Kornhuber, Risks of synchronized low yields are underestimated in climate and crop model projections, Nature Communications (2023). DOI: 10.1038/s41467-023-38906-7. www.nature.com/articles/s41467-023-38906-7

Part 2

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Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 11:41am

We may be underestimating the climate risk to crops: researchers

The risks of harvest failures in multiple global breadbaskets have been underestimated, according to a study  that researchers said should be a "wake up call" about the threat climate change poses to our food systems.

Food production is both a key source of planet-warming emissions and highly exposed to the effects of climate change, with climate and crop models used to figure out just what the impacts could be as the world warms.

In the new research published in Nature Communications, researchers looked at the likelihood that several major food producing regions could simultaneously suffer low yields. These events can lead to price spikes, food insecurity and even civil unrest, according to them.

 By "increasing the concentration of greenhouse gases, we are entering this uncharted water where we are struggling to really have an accurate idea of what type of extremes we're going to face," according to them.  These types of concurring events are really largely underestimated.

Part 1

Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 11:13am

Researchers induce cancer cells to 'commit suicide' with a self-produced bacterial toxin

For the first time in the world researchers  have encoded a toxin produced by bacteria into mRNA (messenger RNA) molecules and delivered these particles directly to cancer cells, causing the cells to produce the toxin—which eventually killed them with a success rate of 50%.

Many bacteria secrete toxins. The most famous of these is probably the botulinum toxin injected in Botox treatments. Another classic treatment technique is chemotherapy, involving the delivery of small molecules through the bloodstream to effectively kill cancer cells. However, chemotherapy has a major downside: it is not selective, and also kills healthy cells. The  idea of this work was to deliver safe mRNA molecules encoded for a bacterial toxin directly to the cancer cells—inducing these cells to actually produce the toxic protein that would later kill them. It's like placing a Trojan horse inside the cancer cell.

First, the research team encoded the genetic info of the toxic protein produced by bacteria of the pseudomonas family into mRNA molecules (resembling the procedure in which genetic info of COVID-19's spike protein was encoded into mRNA molecules to create the vaccine).

The mRNA molecules were then packaged in lipid nanoparticles coated with antibodies—to make sure that the instructions for producing the toxin would reach their target, the cancer cells. The particles were injected into the tumors of animal models with melanoma skin cancer. After a single injection, 44–60% of the cancer cells vanished.

When the cancer cell reads the 'recipe' at the other end it starts to produce the toxin as if it were the bacteria itself and this self-produced toxin eventually kills it. Thus, with a simple injection to the tumor bed, scientists can cause cancer cells to 'commit suicide,' without damaging healthy cells. Moreover, cancer cells cannot develop resistance to this technology as often happens with chemotherapy—because we can always use a different natural toxin.

 Yasmin Granot-Matok et al, Lipid nanoparticles-loaded with toxin mRNA represents a new strategy for the treatment of solid tumors, Theranostics (2023). DOI: 10.7150/thno.82228

Comment by Dr. Krishna Kumari Challa on July 5, 2023 at 11:04am

One night of total sleep deprivation shown to have antidepressant effect for some people

A study  has investigated a seemingly contradictory phenomenon of sleep deprivation leading to mood improvement in patients with depressive disorders.

In a paper, "Enhanced amygdala–cingulate connectivity associates with better mood in both healthy and depressive individuals after sleep deprivation," published in PNAS, the research team mapped brain region activity through resting-state-functional magnetic resonance imaging to see why some people receive a healthy boost from an otherwise negative public health epidemic.

The study finds that one night of total sleep deprivation enhanced amygdala connectivity to the anterior cingulate cortex, which correlated with better mood in some healthy and depressed individuals.

Ya Chai et al, Enhanced amygdala–cingulate connectivity associates with better mood in both healthy and depressive individuals after sleep deprivation, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2214505120

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Comment by Dr. Krishna Kumari Challa on July 4, 2023 at 10:34am

COVID-19 booster vaccine doses strengthen immunity in blood cancer patients, shows study

Research  into the effectiveness of COVID-19 vaccines in people with lymphoma has shown that repeated vaccination increases their ability to prevent infection from the virus, particularly after four doses.

The finding, from the two-year PROSECO study, is important because blood cancer patients have compromised immune systems—either as a result of cancer, or from cancer treatments. This leaves them more vulnerable to COVID-19 than other people and raises questions over how well they respond to vaccination. Latest findings from the study are published in the journal The Lancet.

 Ratna Wijaya et al, Predicting COVID-19 infection risk in people who are immunocompromised by antibody testing, The Lancet (2023). DOI: 10.1016/S0140-6736(23)01180-7

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Urine tests identify brain tumors by capturing cancer DNA using nan...

A group led by researchers at Nagoya University in Japan has developed a technology to capture and release cell-free DNA (cfDNA) on nanowire surfaces from urine. By extracting this DNA, they were able to successfully detect IDH1 mutation, a characteristic genetic mutation of gliomas, a type of brain tumor. Their findings increase the effectiveness of cancer detection tests using urine. They published their results in the journal Biosensors and Bioelectronics.

Comment by Dr. Krishna Kumari Challa on July 4, 2023 at 9:03am

Quasar 'clocks' show the universe was five times slower soon after the Big Bang

Scientists have for the first time observed the early universe running in extreme slow motion, unlocking one of the mysteries of Einstein's expanding universe. The research is published in Nature Astronomy.

Einstein's general theory of relativity means that we should observe the distant—and hence ancient—universe running much slower than the present day. However, peering back that far in time has proven elusive. Scientists have now cracked that mystery by using quasars as "clocks."

Looking back to a time when the universe was just over a billion years old, we see time appearing to flow five times slower, according to these scientists. 

If you were there, in this infant universe, one second would seem like one second—but from our position, more than 12 billion years into the future, that early time appears to drag.

Researchers used observed data from nearly 200 quasars—hyperactive supermassive black holes at the centers of early galaxies—to analyze this time dilation.

Thanks to Einstein, we know that time and space are intertwined and, since the dawn of time in the singularity of the Big Bang, the universe has been expanding. This expansion of space means that our observations of the early universe should appear to be much slower than time flows today. In this new study, scientists have established that back to about a billion years after the Big Bang.

Previously, astronomers have confirmed this slow-motion universe back to about half the age of the universe using supernovae—massive exploding stars—as "standard clocks." But while supernovae are exceedingly bright, they are difficult to observe at the immense distances needed to peer into the early universe.

By observing quasars, this time horizon has been rolled back to just a tenth the age of the universe, confirming that the universe appears to speed up as it ages.

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Where supernovae act like a single flash of light, making them easier to study, quasars are more complex, like an ongoing firework display.

What we have done is unravel this firework display, showing that quasars, too, can be used as standard markers of time for the early universe.

 Detection of the cosmological time dilation of high-redshift quasars, Nature Astronomy (2023). DOI: 10.1038/s41550-023-02029-2 , www.nature.com/articles/s41550-023-02029-2

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