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Comment by Dr. Krishna Kumari Challa on October 7, 2020 at 6:20am

Deciphered: evolution of the Y chromosome in great apes 

New analysis of the DNA sequence of the male-specific Y chromosomes from all living species of the great ape family helps to clarify our understanding of how this enigmatic chromosome evolved. A clearer picture of the evolution of the Y chromosome is important for studying male fertility in humans as well as our understanding of reproduction patterns and the ability to track male lineages in the great apes, which can help with conservation efforts for these endangered species.

A team of biologists and computer scientists sequenced and assembled the Y chromosome from orangutan and bonobo and compared those sequences to the existing human, chimpanzee, and gorilla Y sequences. From the comparison, the team were able to clarify patterns of evolution that seem to fit with behavioural differences between the species and reconstruct a model of what the Y chromosome might have looked like in the ancestor of all great apes.

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The Y chromosome is important for male fertility and contains the genes critical for sperm production, but it is often neglected in genomic studies because it is so difficult to sequence and assemble . The Y chromosome contains a lot of repetitive sequences, which are challenging for DNA sequencing, assembling sequences, and aligning sequences for comparison. There aren't out-of-the-box software packages to deal with the Y chromosome, so we had to overcome these hurdles and optimize our experimental and computational protocols, which allowed us to address interesting biological questions.

The Y chromosome is unusual. It contains relatively few genes, many of which are involved in male sex determination and sperm production; large sections of repetitive DNA, short sequences repeated over and over again; and large DNA palindromes, inverted repeats that can be many thousands of letters long and read the same forwards and backwards.

Previous work by the team comparing human, chimpanzee, and gorilla sequences had revealed some unexpected patterns. Humans are more closely related to chimpanzees, but for some characteristics, the human Y was more similar to the gorilla Y.

Monika Cechova et al, Dynamic evolution of great ape Y chromosomes, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2001749117

https://phys.org/news/2020-10-evolution-chromosome-great-apes-decip...

Comment by Dr. Krishna Kumari Challa on October 7, 2020 at 6:13am

3 scientists win Nobel physics prize for black hole research

Three scientists won the Nobel Prize in physics Tuesday for advancing our understanding of Krishna (means ‘black’ in Sanskrit :)) holes.

Roger Penrose, Reinhard Genzel and Andrea Ghez explained to the world these dead ends of the cosmos that devour light and even time. Staples of both science fact and fiction, black holes are still not completely understood but are deeply connected, somehow, to the creation of galaxies, where the stars and life exist.

Penrose, of the University of Oxford, received half of the prize for discovering that Albert Einstein's general theory of relativity predicts the formation of black holes.

Announcement of the 2020 Nobel Prize in Physics

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 11:01am

Post-viral fatigue syndrome- the condition affecting some COVID-19 survivors

https://theconversation.com/what-is-post-viral-fatigue-syndrome-the...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 10:34am

**T Cells and Neurons Talk to Each Other

Conversations between the immune and central nervous systems are proving to be essential for the healthy social behavior, learning, and memory.

https://www.the-scientist.com/features/t-cells-and-neurons-talk-to-...

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How Trump Could Have Exposed Biden and Others to COVID at the Debate

An expert on airborne virus transmission explains the risks of talking loudly without wearing a mask in an indoor environment

https://www.scientificamerican.com/article/how-trump-could-have-exp...

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https://theconversation.com/we-estimate-there-are-up-to-14-million-...

Microplastics on the seafloor : research suggests there’s a staggering 8-14 million tonnes of it

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 10:01am

Why do mirrors flip horizontally (but not vertically)?

Here's The Physics

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 9:18am

Dozens of mammals could be susceptible to SARS-CoV-2

Numerous animals may be vulnerable to SARS-CoV-2, the virus that causes COVID-19, according to a large study modelling how the virus might infect different animals' cells, led by UCL researchers.

The study, published in Scientific Reports, reports evidence that 26 animals regularly in contact with people may be susceptible to infection.

The researchers investigated how the spike protein from SARS-CoV-2 could interact with the ACE2 protein it attaches to when it infects people.

The focus of the investigation was whether mutations in the ACE2 protein in 215 different animals, that make it different from the human version, would reduce the stability of the binding complex between the virus protein and host protein. Binding to the protein enables the virus to gain entry into host cells; while it is possible the virus might be able to infect animals via another pathway, it is unlikely based on current evidence that the virus could infect an animal if it cannot form a stable binding complex with ACE2.

The researchers found that for some animals, such as sheep and great apes (chimpanzee, gorilla, orangutan, and bonobo, many of which are endangered in the wild), the proteins would be able to bind together just as strongly as they do when the virus infects people. Some of the animals, such as sheep, have not yet been studied with infection tests, so this does not confirm that the animal can indeed be infected.

Scientific Reports (2020). DOI: 10.1038/s41598-020-71936-5

https://phys.org/news/2020-10-dozens-mammals-susceptible-sars-cov-....

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:55am

World's first direct observation of the magneto-Thomson effect

Applying a temperature gradient and a charge current to an electrical conductor leads to the release and absorbtion of heat. This is called the Thomson effect. In a first, researchers have directly observed the magneto-Thomson effect, which is the magnetic-field-induced modulation of the Thomson effect. This success may contribute to the development of new functions and technologies for thermal energy management and to advances in fundamental physics and materials .

science on magneto-thermoelectric conversion.

Kelly Morrison et al. Thermal Imaging of the Thomson Effect, Physics (2020). DOI: 10.1103/Physics.13.137

https://phys.org/news/2020-10-world-magneto-thomson-effect.html?utm...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:34am

**Scientists find evidence of exotic state of matter in candidate material for quantum computers

Using a novel technique, scientists have found evidence for a quantum spin liquid, a state of matter that is promising as a building block for the quantum computers of tomorrow.

Researchers discovered the exciting behavior while studying the so-called electron spins in the compound ruthenium trichloride. The findings show that electron spins interact across the material, effectively lowering the overall energy. This type of behaviour—consistent with a quantum spin liquid—was detected in ruthenium trichloride at high temperatures and in high magnetic fields.

K. A. Modic et al, Scale-invariant magnetic anisotropy in RuCl3 at high magnetic fields, Nature Physics (2020). DOI: 10.1038/s41567-020-1028-0

https://phys.org/news/2020-10-scientists-evidence-exotic-state-cand...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:24am

Normally an insulator, diamond becomes a metallic conductor when subjected to large strain in a new theoretical model

Long known as the hardest of all natural materials, diamonds are also exceptional thermal conductors and electrical insulators. Now, researchers have discovered a way to tweak tiny needles of diamond in a controlled way to transform their electronic properties, dialing them from insulating, through semiconducting, all the way to highly conductive, or metallic. This can be induced dynamically and reversed at will, with no degradation of the diamond material.

The research may open up a wide array of potential applications, including new kinds of broadband solar cells, highly efficient LEDs and power electronics, and new optical devices or quantum sensors.

The methods demonstrated in this work could be applied to a broad range of other semiconductor materials of technological interest in mechanical, microelectronics, biomedical, energy and photonics applications, through strain engineering.

Zhe Shi el al., "Metallization of diamond," PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2013565117

https://phys.org/news/2020-10-scientists-electrifying-diamond.html?...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:14am

Neuroscientists discover a molecular mechanism that allows memories to form

When the brain forms a memory of a new experience, neurons called engram cells encode the details of the memory and are later reactivated whenever we recall it. A new  study reveals that this process is controlled by large-scale remodeling of cells' chromatin.

This remodeling, which allows specific genes involved in storing memories to become more active, takes place in multiple stages spread out over several days. Changes to the density and arrangement of chromatin, a highly compressed structure consisting of DNA and proteins called histones, can control how active specific genes are within a given cell.

This paper is the first to really reveal this very mysterious process of how different waves of genes become activated, and what is the epigenetic mechanism underlying these different waves of gene expression.

Engram cells are found in the hippocampus as well as other parts of the brain. Many recent studies have shown that these cells form networks that are associated with particular memories, and these networks are activated when that memory is recalled. However, the molecular mechanisms underlying the encoding and retrieval of these memories are not well-understood.

Neuroscientists know that in the very first stage of memory formation, genes known as immediate early genes are turned on in engram cells, but these genes soon return to normal activity levels.

The formation and preservation of memory is a very delicate and coordinated event that spreads over hours and days, and might be even months—we don't know for sure," Marco says. "During this process, there are a few waves of gene expression and protein synthesis that make the connections between the neurons stronger and faster."

Tsai and Marco hypothesized that these waves could be controlled by epigenomic modifications, which are chemical alterations of chromatin that control whether a particular gene is accessible or not. Previous studies from Tsai's lab have shown that when enzymes that make chromatin inaccessible are too active, they can interfere with the ability to form new memories. Many of the genes turned on during memory recall are involved in promoting protein synthesis at the synapses, helping neurons strengthen their connections with other neurons. The researchers also found that the neurons' dendrites—branched extensions that receive input from other neurons—developed more spines, offering further evidence that their connections were further strengthened.

The study is the first to show that memory formation is driven by epigenomically priming enhancers to stimulate gene expression when a memory is recalled.

 Mapping the epigenomic and transcriptomic interplay during memory formation and recall in the hippocampal engram ensemble, Nature Neuroscience (2020). DOI: 10.1038/s41593-020-00717-0 , www.nature.com/articles/s41593-020-00717-0

https://medicalxpress.com/news/2020-10-neuroscientists-molecular-me...

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