Comment

Comment by Dr. Krishna Kumari Challa on July 6, 2023 at 12:04pm

Although M. mycoides JCVI-syn3B could grow and divide in laboratory conditions, researchers wanted to know how a minimal cell would respond to the forces of evolution over time, particularly given the limited raw materials upon which natural selection could operate as well as the uncharacterized input of new mutations.

"Everysingle gene in its genome is essential" with reference to M. mycoides JCVI-syn3B. "One could hypothesize that there is no wiggle room for mutations, which could constrain its potential to evolve."

The researchers established that M. mycoides JCVI-syn3B, in fact, has an exceptionally high mutation rate. They then grew it in the lab where it was allowed to evolve freely for 300 days, equivalent to 2,000 bacterial generations or about 40,000 years of human evolution.

The next step was to set up experiments to determine how the minimal cells that had evolved for 300 days performed in comparison to the original, non-minimal M. mycoides as well as to a strain of minimal cells that hadn't evolved for 300 days. In the comparison tests, the researchers put equal amounts of the strains being assessed together in a test tube. The strain better suited to its environment became the more common strain.

They found that the non-minimal version of the bacterium easily outcompeted the unevolved minimal version. The minimal bacterium that had evolved for 300 days, however, did much better, effectively recovering all of the fitness that it had lost due to genome  streamlining. The researchers identified the genes that changed the most during evolution. Some of these genes were involved in constructing the surface of the cell, while the functions of several others remain unknown.

Understanding how organisms with simplified genomes overcome evolutionary challenges has important implications for long-standing problems in biology—including the treatment of clinical pathogens, the persistence of host-associated endosymbionts, the refinement of engineered microorganisms, and the origin of life itself.

this demonstrates the power of natural selection to rapidly optimize fitness in the simplest autonomous organism, with implications for the evolution of cellular complexity. In other words, it shows that life finds a way.

Jay Lennon, Evolution of a minimal cell, Nature (2023). DOI: 10.1038/s41586-023-06288-x. www.nature.com/articles/s41586-023-06288-x

Part 2

**

Comment by Dr. Krishna Kumari Challa on July 6, 2023 at 12:01pm

Artificial cells demonstrate that 'life finds a way'

Evolutionary biologists  have been studying a synthetically constructed minimal cell that has been stripped of all but its essential genes. They found that the streamlined cell can evolve just as fast as a normal cell—demonstrating the capacity for organisms to adapt, even with an unnatural genome that would seemingly provide little flexibility.

This shows that if there's one thing the history of evolution has taught us is that life will not be contained. Life breaks free. It expands to new territories, and it crashes through barriers painfully, maybe even dangerously, but . . . life finds a way.

It appears there's something about life that's really robust. We can simplify it down to just the bare essentials, but that doesn't stop evolution from going to work.

For their study,  the researchers used the synthetic organism, Mycoplasma mycoides JCVI-syn3B—a minimized version of the bacterium M. mycoides commonly found in the guts of goats and similar animals. Over millennia, the parasitic bacterium has naturally lost many of its genes as it evolved to depend on its host for nutrition.

Researchers at the J. Craig Venter Institute in California took this one step further. In 2016, they eliminated 45% of the 901 genes from the natural M. mycoides genome—reducing it to the smallest set of genes required for autonomous cellular life. At 493 genes, the minimal genome of M. mycoides JCVI-syn3B is the smallest of any known free-living organism. In comparison, many animal and plant genomes contain more than 20,000 genes.

In principle, the simplest organism would have no functional redundancies and possess only the minimum number of genes essential for life. Any mutation in such an organism could lethally disrupt one or more cellular functions, placing constraints on evolution. Organisms with streamlined genomes have fewer targets upon which positive selection can act, thus limiting opportunities for adaptation.

Part 1

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

More work will be needed to determine whether the impact of climate change on Homo physiology is a result specifically of temperature changes or an indirect effect from other elements of a changing environment.

https://karger.com/bbe/article/98/2/93/835670/Climate-Change-Influe...

Part 2

**

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

**

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

**

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

• ‹ Previous
• 1
• …
• 363
• 364
• 365
• 366
• 367
• …
• 1082
• Next ›
• Page