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Comment by Dr. Krishna Kumari Challa on October 20, 2021 at 9:03am

New understanding on how brain cells talk

Researchers have discovered that reversing the modification of molecular messages at synapses in the human brain, may contribute to reversible mental health conditions such as anxiety, and memory diseases such as dementia.

The findings are a major step in our understanding how brain cells  communicate, and could help to identify new treatments for neurological and psychiatric conditions.

Nerve cells in the human brain talk to one another at sites called synapses, where molecules are released to signal to the next cell. When people learn or remember things, this signaling is strengthened. When communication between synapses goes wrong, circuits become broken. As more circuits are lost, this changes how people can think and perform everyday tasks. This is seen in cognitive disorders, such as forms of dementia and some mental health conditions.

The function of nerve cells and synapses depends on proteins that are made using information encoded in genetic material called RNA. It is thought that RNAs are located exactly where and when they are needed for synaptic signaling because some kind of synaptic 'tag' labels the correct active synapse. Scientists have recently learnt that RNA can have a methyl group/molecule added to one of the RNA bases which 'marks' the RNA message. Such adding of methyl groups can influence proteins binding to DNA or RNA and consequently stop proteins being produced.

This new study shows that RNA marking can be reversed at synapses and hence may act as a 'synaptic tag'. The findings suggest, that if disrupted, this could cause synapses and nerve cells to malfunction by influencing the formation of toxic protein clumps.

The researchers used advanced microscopy to examine changes in marked RNAs in time and location at synapses, and a sequencing technique to characterize 'marked' RNAs in brain tissue from the hippocampus, a region of the brain very important for memory formation.

 are able to gain a new understanding of the genomic mechanisms which regulate how nerve cells communicate at synapses. These genomic mechanisms involve methyl groups being put on RNA messages and importantly taken off when a synapse is active. The implications are very important for normal brain function but also for reversible psychiatric mental conditions such as anxiety and addiction disorders and early-stage neurodegenerative diseases such as dementias.

Braulio Martinez De La Cruz et al, Modifying the m6A brain methylome by ALKBH5-mediated demethylation: a new contender for synaptic tagging, Molecular Psychiatry (2021). DOI: 10.1038/s41380-021-01282-z

https://medicalxpress.com/news/2021-10-scientists-gain-brain-cells....

Comment by Dr. Krishna Kumari Challa on October 19, 2021 at 10:46am

Researchers  came up with a plan for settling the debate once and for all.

 The international team of researchers then placed their bet that paleomagnetic data from limestones created in the Cretaceous (between ~145.5 and 65.5 million years ago) located in Italy would provide a definitive test. The magnetism of the younger rocks in the same area was studied nearly 50 years ago, and indirectly led to the discovery of the asteroid impact that killed the dinosaurs. These Italian sedimentary rocks turn out to be special and very reliable because the magnetic minerals are actually fossils of bacteria that formed chains of the mineral magnetite.

To test their hypothesis about true polar wander, paleomagnetic data with lots of redundancy are required to track the wander of the ancient location of Earth's spin axis. Prior studies, especially some claiming that true polar wander does not occur, have failed to explore enough data points according to the team.

That is one reason why it is so refreshing to see this study with its abundant and beautiful paleomagnetic data.

As the true polar wander hypothesis predicted, the Italian data indicate an ~12˚ tilt of the planet 84 million years ago. The team also found that Earth appears to have corrected itself—after tipping on its side, Earth reversed course and rotated right back, for a total excursion of nearly 25˚ of arc in about five million years. Certainly, this was a cosmic "yo-yo.

Ross N. Mitchell et al, A Late Cretaceous true polar wander oscillation, Nature Communications (2021). DOI: 10.1038/s41467-021-23803-8

https://phys.org/news/2021-10-earth-side-million-years.html?utm_sou...

Part 2

**

Comment by Dr. Krishna Kumari Challa on October 19, 2021 at 10:44am

Did the Earth tip on its side 84 million years ago?

scientists have found more evidence that Earth tips over from time to time. We know that the continents are moving slowly due to plate tectonics, but continental drift only pushes the tectonic plates past each other. It has been debated for the past few decades whether the outer, solid shell of the Earth can wobble about, or even tip over relative to the spin axis. Such a shift of Earth is called "true polar wander," but the evidence for this process has been contentious. New research published in Nature Communications, led by the Earth-Life Science Institute (ELSI) and Institute of Geology and Geophysics in Beijing, provides some of the most convincing evidence to date that such planetary tipping has indeed occurred in Earth's past.

True polar wander bears some dissecting. The Earth is a stratified ball, with a solid metal inner core, a liquid metal outer core, and a solid mantle and overriding crust at the surface which we live on. All of this is spinning like a top, once per day. Because the Earth's outer core is liquid, the solid mantle and crust are able to slide around on top of it. Relatively dense structures, such as subducting oceanic plates and massive volcanoes like Hawaii, prefer to be near the Equator, in the same way that your arms like to be out to your side when you are spinning around in an office chair.

Despite this wandering of the crust, Earth' magnetic field is generated by electrical currents in the convecting liquid Ni-Fe metal of the outer core. On long time scales, the overlying wander of the mantle and crust does not affect the core, because those overlying rock layers are transparent to Earth's magnetic field. In contrast, the convection patterns in this outer core are actually forced to dance around Earth's rotation axis, which means that the overall pattern of Earth's magnetic field is predictable, spreading out in the same fashion as iron filings lining up over a small bar magnet. Hence, these data provide excellent information about the direction of the North and South geographic poles, and the tilt gives the distance from the poles (a vertical field means you are at the pole, horizontal tells us it was on the Equator). Many rocks actually record the direction of the local magnetic field as they form, in much the same way that a magnetic tape records your music. For example, tiny crystals of the mineral magnetite produced by some bacteria actually line up like tiny compass needles, and get trapped in the sediments when the rock solidifies. This "fossil" magnetism can be used to track where the spin axis is wandering relative to the crust.

Imagine looking at Earth from space. True polar wander would look like the Earth tipping on its side, and what's actually happening is that the whole rocky shell of the planet—the solid mantle and crust—is rotating around the liquid outer core. Although scientists can measure true polar wander occurring today very precisely with satellites, geologists still debate whether large rotations of the mantle and crust have occurred in Earth's past.

part 1

Researchers  came up with a plan for settling the debate once and for all.

Comment by Dr. Krishna Kumari Challa on October 19, 2021 at 10:05am

So-called junk DNA plays critical role in mammalian development

Nearly half of our DNA has been written off as junk, the discards of evolution: Sidelined or broken genes, viruses that got stuck in our genome and were dismembered or silenced, none of it relevant to the human organism or human evolution.

But research over the last decade has shown that some of this genetic "dark matter" does have a function, primarily in regulating the expression of host genes—a mere 2% of our total genome—that code for proteins. Biologists continue to find whether these regulatory sequences of DNA play essential or detrimental roles in the body or are merely incidental, an accident that the organism can live without.

A new study explored the function of one component of this junk DNA, transposons, which are selfish DNA sequences able to invade their host genome. The study shows that at least one family of transposons—ancient viruses that have invaded our genome by the millions—plays a critical role in viability in the mouse, and perhaps in all mammals. When the researchers knocked out a specific transposon in mice, half their mouse pups died before birth.

This is the first example of a piece of "junk DNA" being critical to survival in mammals.

In mice, this transposon regulates the proliferation of cells in the early fertilized embryo and the timing of implantation in the mother's uterus. The researchers looked in seven other mammalian species, including humans, and also found virus-derived regulatory elements linked to cell proliferation and timing of embryo implantation, suggesting that ancient viral DNA has been domesticated independently to play a crucial role in early embryonic development in all mammals.

Andrew J. Modzelewski et al, A mouse-specific retrotransposon drives a conserved Cdk2ap1 isoform essential for development, Cell (2021). DOI: 10.1016/j.cell.2021.09.021

https://phys.org/news/2021-10-so-called-junk-dna-critical-role.html...

Comment by Dr. Krishna Kumari Challa on October 18, 2021 at 7:50am

Comment by Dr. Krishna Kumari Challa on October 18, 2021 at 7:43am

It's not tough.

4*4+4*4+4–4*4

=16+16+4–16 ( according to BODMAS)

=20

--

(4x4)+(4x4)+4-(4x4)
16+26+4–16=20

--

(4 x 4) + (4 x 4) + 4 -(4 x 4) =
(16) + (16) + 4 - (16) =
36 - 16 = 20.

--

20 is the answer according to BODMAS

Hint: Use BODMAS Rule.
B - Brackets
O - Of
D - Division
M - Multiplication
A - Addition
S - Subtraction

You need to do the calculations in this order, B to S.

Comment by Dr. Krishna Kumari Challa on October 16, 2021 at 9:34am

RFusion: A Robot that Finds and Retrieves Missing Objects

Comment by Dr. Krishna Kumari Challa on October 16, 2021 at 9:12am

Did you know that  every one of us has a brain "fingerprint" and that this fingerprint changes over time?

Comparing the graphs generated from MRI scans of the same subjects taken a few days apart, researchers were able to correctly match up the two scans of a given subject nearly 95% of the time. In other words, they could accurately identify an individual based on their brain fingerprint. That's really impressive because the identification was made using only functional connectomes, which are essentially sets of correlation scores.

When researchers compared  the brain fingerprints of healthy patients with those suffering from Alzheimer's disease. Based on their initial findings, it seems that the features that make a brain fingerprint unique steadily disappear as the disease progresses. It gets harder to identify people based on their connectomes. It's as if a person with Alzheimer's loses his or her brain identity.

Along this line, potential applications might include early detection of neurological conditions where brain fingerprints get disappear. This technique can be used in patients affected by autism, or stroke, or even in subjects with drug addictions. This is just another little step towards understanding what makes our brains unique: the opportunities that this insight might create are limitless.

Dimitri Van De Ville et al, When makes you unique: temporality of the human brain fingerprint, Science Advances (2021). DOI: 10.1126/sciadv.abj0751. www.science.org/doi/10.1126/sciadv.abj0751

https://medicalxpress.com/news/2021-10-brains-fingerprint.html?utm_...

Comment by Dr. Krishna Kumari Challa on October 15, 2021 at 12:13pm

Researchers engineer microorganisms to tackle PET plastic pollution

From overflowing landfills to floating garbage islands in the oceans to microplastics in remote wilderness areas, billions of tons of discarded plastic have created a global pollution crisis.

Comment by Dr. Krishna Kumari Challa on October 15, 2021 at 12:08pm

After two hours, sunscreen that includes zinc oxide loses effectiveness, becomes toxic: study

Sunscreen that includes zinc oxide, a common ingredient, loses much of its effectiveness and becomes toxic after two hours of exposure to ultraviolet radiation, according to a study by scientists.

The toxicity analysis involved zebrafish, which share a remarkable similarity to humans at the molecular, genetic and cellular levels, meaning many zebrafish studies are immediately relevant to people.

Findings were published recently in Photochemical & Photobiological Sciences.

Sunscreens are important consumer products that help to reduce UV exposures and thus skin cancer, but we do not know if the use of some sunscreen formulations may have unintended toxicity because of interactions between some ingredients and UV light.

And sunscreens containing inorganic compounds like zinc oxide or titanium dioxide, that block UV rays, are being marketed more and more heavily as safe alternatives to the organic small-molecule compounds that absorb the rays.

In the experiments conducted now, zinc oxide degraded the organic mixture and caused a greater than 80% loss in organic filter protection against ultraviolet-A rays, which make up 95% of the UV radiation that reaches the Earth. Also, the zinc-oxide-induced photodegradation products caused significant increases in defects to the zebrafish we used to test toxicity. That suggests zinc oxide particles are leading to degradants whose introduction to aquatic ecosystems is environmentally hazardous.

Aurora L. Ginzburg et al, Zinc oxide-induced changes to sunscreen ingredient efficacy and toxicity under UV irradiation, Photochemical & Photobiological Sciences (2021). DOI: 10.1007/s43630-021-00101-2

https://phys.org/news/2021-10-hours-sunscreen-zinc-oxide-effectiven...

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