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Comment by Dr. Krishna Kumari Challa on October 2, 2020 at 6:14am

Key control mechanism allows cells to form tissues and anatomical structures in the developing embryo

Under a microscope, the first few hours of every multicellular organism's life seem incongruously chaotic. After fertilization, a once tranquil single-celled egg divides again and again, quickly becoming a visually tumultuous mosh pit of cells jockeying for position inside the rapidly growing embryo. amid this apparent pandemonium, cells begin to self-organize. Soon, spatial patterns emerge, serving as the foundation for the construction of tissues, organs and elaborate anatomical structures from brains to toes and everything in between. For decades, scientists have intensively studied this process, called morphogenesis, but it remains in many ways enigmatic.

Now researchers have discovered a key control mechanism that cells use to self-organize in early embryonic development. 

Studying spinal cord formation in zebrafish embryos, a team revealed that different cell types express unique combinations of adhesion molecules in order to self-sort during morphogenesis. These "adhesion codes" determine which cells prefer to stay connected, and how strongly they do so, even as widespread cellular rearrangements occur in the developing embryo.

The researchers found that adhesion codes are regulated by morphogens, master signaling molecules long known to govern cell fate and pattern formation in development. The results suggest that the interplay of morphogens and adhesion properties allows cells to organize with the precision and consistency required to construct an organism.

Three genes—N-cadherin, cadherin 11 and protocadherin 19—emerged as essential for normal patterning. The expression of different combinations and different levels of these genes was responsible for differences in adhesion preference, representing what the team dubbed an adhesion code. This code was unique to each of the cell types and determined which other cells each cell type stays connected to during morphogenesis.

The analyses revealed that both cell type and adhesion-molecule gene expression were highly correlated, both in level and spatial position. This held true across the entire nascent spinal cord, where patterns of gene expression for cell type and adhesion molecule changed together in response to differences in Shh activity.

What they found is that this morphogen not only controls cell fate, it controls cell adhesion

Insights into how cells self-organize in early development could also aid efforts to engineer tissues and organs for clinical uses such as transplantation.

"An adhesion code ensures robust pattern formation during tissue morphogenesis" Science (2020). science.sciencemag.org/lookup/ … 1126/science.aba6637

https://phys.org/news/2020-10-key-mechanism-cells-tissues-anatomica...

Comment by Dr. Krishna Kumari Challa on October 2, 2020 at 5:51am

Einstein's description of gravity just got much harder to beat

Einstein's theory of general relativity—the idea that gravity is matter warping spacetime—has withstood over 100 years of scrutiny and testing, including the newest test from the Event Horizon Telescope collaboration which  is a brand-new way to test general relativity using supermassive black holes.

According to the findings, Einstein's theory just got 500 times harder to beat.

Despite its successes, Einstein's robust theory remains mathematically irreconcilable with quantum mechanics, the scientific understanding of the subatomic world. Testing general relativity is important because the ultimate theory of the universe must encompass both gravity and quantum mechanics.

To perform the test, the team used the first image ever taken of the supermassive black hole at the center of nearby galaxy M87 obtained with the EHT last year. The first results had shown that the size of the black-hole shadow was consistent with the size predicted by general relativity.

The team did a very broad analysis of many modifications to the theory of general relativity to identify the unique characteristic of a theory of gravity that determines the size of a black hole shadow.

In this way, scientists can now pinpoint whether some alternative to general relativity is in agreement with the Event Horizon Telescope observations, without worrying about any other details. The team focused on the range of alternatives that had passed all the previous tests in the solar system.

Using the gauge they developed, they showed that the measured size of the black hole shadow in M87 tightens the wiggle room for modifications to Einstein's theory of general relativity by almost a factor of 500, compared to previous tests in the solar system. Many ways to modify general relativity fail at this new and tighter black hole shadow test.

Black hole images provide a completely new angle for testing Einstein's theory of general relativity

Dimitrios Psaltis et al. Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole, Physical Review Letters (2020). dx.doi.org/10.1103/PhysRevLett.125.141104

https://phys.org/news/2020-10-einstein-description-gravity-harder.h...

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 10:07am

Smart Underwear Prevents Back Stress with just a Double Tap

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Inside mitochondria and their fascinating genome

EPFL scientists have observed – for the first time in living cells – the way mitochondria distribute their transcriptome throughout the cell, and it involves RNA granules that turn out to be highly fluid.

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 9:37am

Science and scientists highly regarded across globe: survey

As citizens across the world await a vaccine to end the coronavirus pandemic, a survey by Pew Research Center published Tuesday has good news: scientists and their research are widely viewed positively across much of the globe.

Majorities said the media does a good job covering science, but also said the public often doesn't know enough to understand news on scientific research.

Around two-thirds or more said the news media do a very or somewhat good job covering science topics, while far fewer said the media do a bad job covering science -- medians of 68 percent against 28 percent across the 20 countries.

But across the countries surveyed, 74 percent considered limited public understanding of science to be a problem for media coverage of science research.

https://www.pewresearch.org/science/2020/09/29/science-and-scientis...

https://researchnews.cc/news/2788/Science-and-scientists-highly-reg...

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 9:16am

Gene expression altered by direction of forces acting on cell

Tissues and cells in the human body are subjected to a constant push and pull – strained by other cells, blood pressure and fluid flow, to name a few. The type and direction of the force on a cell alters gene expression by stretching different regions of DNA, researchers found in a new study.

The findings could provide insights into physiology and diseases such as fibrosis, cardiovascular disease and malignant cancer, the researchers said.

Force is everywhere in the human body, and both external and internal forces can influence your body far more than you may have thought. These strains profoundly influence cellular behaviours and physiological functions, which are initiated at the level of gene expression.

They found that the force from the magnetic bead caused a rapid increase in expression for certain genes, but the amount of the increase depended on the direction the bead moved. When the bead rolled along the long axis of the cell, the increase was the lowest, but when the force was applied perpendicularly – across the short axis of the cell – gene activity increased the most. When the bead was moved at a 45-degree angle or rotated in the same plane as the cell to induce shear stress, the response was intermediate.
These observations show that gene upregulation and activation are very sensitive to the mode of the applied force, when the magnitude of the force remains unchanged.

In further experiments, the researchers found that the reason for the difference lies in the method that the forces are relayed to the cell’s nucleus, where DNA is housed. Cells have a network of support structures called the cytoskeleton, and the main force-bearing elements are long fibers of the protein actin. When they bend due to a force, they relay that force to the nucleus and stretch the chromosomes.

These actin fibers run lengthwise along the cell. So when the force strains them widthwise, they deform more, stretching the chromosomes more and causing greater gene activity, the researchers found.

https://news.illinois.edu/view/6367/385931150

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 8:55am

Pregnancy Loss: A possible link between olfaction and miscarriage

Unexplained repeated pregnancy loss is associated with an altered perception of male odors and differences in brain regions that process smells.

Exposing female rodents to the smell of adult males can lead to synchronized menstrual cycling  and accelerated sexual maturation, as well as to embryos failing to implant in the uterus . Olfactory cues might also play a role in human reproduction: for instance, the menstrual cycle phase may influence preferences for male odors . This presents the possibility that altered neural processing of socially relevant odors, such as the scent of a partner, may be linked to pregnancy loss and other reproductive disorders. Now researchers report that women who have experienced unexplained repeated pregnancy loss process the odors of males differently.

https://elifesciences.org/articles/62534?utm_source=content_alert&a...

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 8:39am

India pushes bold ‘one nation, one subscription’ journal-access plan

Researchers will also recommend an open-access policy that promotes research being shared in online repositories.The Indian government is pushing a bold proposal that would make scholarly literature accessible for free to everyone in the country. The government wants to negotiate with the world’s biggest scientific publishers to set up nationwide subscriptions, rather than many agreements with individual institutions that only scholars can use, say researchers consulting for the government.

The proposal is expected to be part of the government’s latest science, technology and innovation policy.

If successful, India would become the largest country to strike deals that give access to paywalled articles to all citizens — more than 1.3 billion people — say researchers.

https://www.nature.com/articles/d41586-020-02708-4

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 7:10am

Dinosaur feather study debunked: Overwhelming evidence supports Jurassic fossil does belong to Archaeopteryx

A new study provides substantial evidence that the first fossil feather ever to be discovered does belong to the iconic Archaeopteryx, a bird-like dinosaur named in Germany on this day in 1861. This debunks a recent theory that the fossil feather originated from a different species.

The new research finds that the Jurassic fossil matches a type of wing feather called a primary covert. Primary coverts overlay the primary feathers and help propel birds through the air. Researchers analyzed nine attributes of the feather, particularly the long quill, along with data from modern birds. They also examined the 13 known skeletal fossils of Archaeopteryx, three of which contain well-preserved primary coverts. The researchers discovered that the top surface of an Archaeopteryx wing has primary coverts that are identical to the isolated feather in size and shape. The isolated feather was also from the same fossil site as four skeletons of Archaeopteryx, confirming their findings.

Through scientific detective work that combined new techniques with old fossils and literature, scientists were able to finally solve these centuries-old mysteries.

Using a specialized type of electron microscope, the researchers determined that the feather came from the left wing. They also detected melanosomes, which are microscopic pigment structures. After refining their color reconstruction, they found that the feather  was entirely matte black, not black and white as another study has claimed.

Evidence corroborates identity of isolated fossil feather as a wing covert of Archaeopteryx, Scientific Reports (2020). doi.org/10.1038/s41598-020-65336-y

https://phys.org/news/2020-09-dinosaur-feather-debunked-overwhelmin...

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 6:12am

Mutations that affect aging: More common than we thought?

The number of mutations that can contribute to aging may be significantly higher than previously believed, according to new research on fruit flies. 

Many functions of our bodies deteriorate slowly but surely as we age, and eventually an organism dies. This thought may not be very encouraging, but most of us have probably accepted that this is the fate of all living creatures—death is part of life. However, those who study evolutionary biology find it far from clear why this is the case. The evolution of aging is, in a manner of speaking, a paradox. Evolution causes continuous adaptation in organisms, but even so it has not resulted in them ceasing to age.

Nearly 70 years ago, evolutionary biologists proposed two theories concerning two different types of mutation that contribute to aging. Both of these mutations have a detrimental effect as the organism becomes older—which leads to aging—while they are either advantageous or neutral early in life. Researchers have, however, not been able to determine which of the two types of mutation contributes most to aging, despite experimental studies.

A new theory was proposed a few years ago suggesting that aging is caused by mutations with a detrimental effect early in life, and whose negative effects increase with age. Those who support this hypothesis believe that many of the mutations that arise have negative effects right from the start, compared with the normal variant of a gene.

The study now published describes experiments to test the theory of mutations that have a detrimental effect throughout life and contribute to aging. The authors used one of the most well-studied animals in the world, namely the fruit fly, or Drosophila melanogaster. They tested 20 different mutations that they had placed into the genetic material of the flies. For each individual mutation, they studied a group of flies with the mutation and a control group without it. Each mutation had a specific, visible effect, which made it easy to follow, such as a somewhat different appearance of the wings or a different shape of the eyes.

As an organism ages, the probability that an individual dies increases, and its ability to reproduce falls. The researchers determined the fertility of the fruit flies and used it as a measure of aging. They counted the number of eggs laid by each female early in life, after two weeks, and finally after a further two weeks (which is a ripe old age for a fruit fly!). The researchers wanted to see whether the difference between flies with the mutations and the control group changed as they aged. The results support the theory they were testing. Most of the mutations had a negative effect on the fertility of the fruit flies early in life, and most of them also caused reproductive aging to occur more rapidly.

The results suggest that mutations that are detrimental early in life can also contribute to aging. Thus it may be that mutations that bring on aging are significantly more common than we previously thought.

 "Deleterious mutations show increasing negative effects with age in Drosophila melanogaster", Martin I. Brengdahl, Christopher M. Kimber, Phoebe Elias, Josephine Thompson and Urban Friberg, (2020), BMC Biology, published online 30 September, DOI: 10.1186/s12915-020-00858-5

https://phys.org/news/2020-09-mutations-affect-aging-common-thought...

Comment by Dr. Krishna Kumari Challa on October 1, 2020 at 6:00am

Achieving invisibility: Cross-wavelength invisibility integrated with invisibility tactics

Using biomimicry - the natural ecological relationship between transparent oceanic animals and their predators that employ a cross-wavelength detection strategy - proposed a new concept of cross-wavelength invisibility that integrated a variety of invisibility tactics. They presented a Boolean metamaterial design strategy to balance divergent material requirements across cross-scale wavelengths. As proof of concept, they simultaneously demonstrated longwave cloaking and shortwave transparency using a nanoimprinting technique. The work extended stealth techniques from individual strategies of invisibility targeting a single-wavelength spectrum to integrated invisibility targeting cross-wavelength applications. These experiments will pave the way to develop cross-wavelength integrated metadevices.

The new strategy complements existing mainstream strategies of chameleon-like adaptive camouflage and the wave-bypassing invisibility cloak.  In this work, scientists break the existing ecological relationship by attempting to hide the transparent prey from the cross-spectral vision of their predators. As a result, this philosophy of invisibility will be of significance for practical stealth technologies.

Xu S. et al. Cross-wavelength invisibility integrated with various invisibility tactics, Science Advances, 10.1126/sciadv.abb3755

Ni X. et al. An ultrathin invisibility skin cloak for visible light, Science, 10.1126/science.aac9411

Landy N. et al. A full-parameter unidirectional metamaterial cloak for microwaves. Nature Materials, doi.org/10.1038/nmat3476

https://phys.org/news/2020-09-invisibility-cross-wavelength-tactics...

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