Comment

Comment by Dr. Krishna Kumari Challa on November 25, 2022 at 10:05am

Scientists reveal first close-up look at bats' immune response to live infection

In a world first, scientists  have sequenced the response to viral infection in colony-bred cave nectar bats (Eonycteris spelaea) at single-cell resolution. Published in the journal Immunity, the findings contribute to insights into bat immunity that could be harnessed to protect human health.

Bats harbor many types of viruses. Even when they are infected with viruses deadly to humans, they show no notable signs or symptoms of disease. By understanding how bats' immune responses protect them from infections, we may find clues that will help humans to better combat viral infections.

And knowing how to better fight viral infections can aid in the development of treatments that will help us to be more bat-like—by falling sick less and aging better.

In this study, the scientists investigated bat immune responses to Malacca virus, a double-stranded RNA virus that uses bats as its natural reservoir. This virus also causes mild respiratory disease in humans.

The team used single-cell transcriptome sequencing to study lung immune responses to infections at the cellular level, identifying the different types of immune cells in bats—some of which are different from those in other mammals, including humans—and uncovering what they do in response to such viral infections.

They found that a type of white blood cell, called neutrophils, showed a very high expression of a gene called IDO1, which is known to play a role in mediating immune suppression in humans. The scientists think that IDO1 expression in cave nectar bats could play an important role in limiting inflammation following infection.

Researchers also found marked anti-viral gene signatures in white blood cells known as monocytes and alveolar macrophages, which—in a sense—consume viral particles and then teach T cells how to recognize the virus. This observation is interesting as it shows that bats clearly activate an immune response following infection despite showing few outward symptoms or pathology. The team also identified an unusual diversity and abundance of T cells and natural killer cells—named for their ability to kill tumor cells and cells infected with a virus—in the cave nectar bat, which are broadly activated to respond to the infection.

Akshamal M. Gamage et al, Single-cell transcriptome analysis of the in vivo response to viral infection in the cave nectar bat Eonycteris spelaea, Immunity (2022). DOI: 10.1016/j.immuni.2022.10.008

Comment by Dr. Krishna Kumari Challa on November 25, 2022 at 9:29am

New CRISPR-based tool inserts large DNA sequences at desired sites in cells

Building on the CRISPR gene-editing system, researchers have designed a new tool that can snip out faulty genes and replace them with new ones, in a safer and more efficient way.

Using this system, the researchers showed that they could deliver genes as long as 36,000 DNA base pairs to several types of human cells, as well as to liver cells in mice. The new technique, known as PASTE, could hold promise for treating diseases that are caused by defective genes with a large number of mutations, such as cystic fibrosis.

The new tool combines the precise targeting of CRISPR-Cas9, a set of molecules originally derived from bacterial defense systems, with enzymes called integrases, which viruses use to insert their own genetic material into a bacterial genome.

Just like CRISPR, these integrases come from the ongoing battle between bacteria and the viruses that infect them. 

--

The CRISPR-Cas9 gene editing system consists of a DNA-cutting enzyme called Cas9 and a short RNA strand that guides the enzyme to a specific area of the genome, directing Cas9 where to make its cut. When Cas9 and the guide RNA targeting a disease gene are delivered into cells, a specific cut is made in the genome, and the cells' DNA repair processes glue the cut back together, often deleting a small portion of the genome.

If a DNA template is also delivered, the cells can incorporate a corrected copy into their genomes during the repair process. However, this process requires cells to make double-stranded breaks in their DNA, which can cause chromosomal deletions or rearrangements that are harmful to cells. Another limitation is that it only works in cells that are dividing, as nondividing cells don't have active DNA repair processes.

This new work deals with a tool that could cut out a defective gene and replace it with a new one without inducing any double-stranded DNA breaks. To achieve this goal, they turned to a family of enzymes called integrases, which viruses called bacteriophages use to insert themselves into bacterial genomes.

For this study, the researchers focused on serine integrases, which can insert huge chunks of DNA, as large as 50,000 base pairs. These enzymes target specific genome sequences known as attachment sites, which function as "landing pads." When they find the correct landing pad in the host genome, they bind to it and integrate their DNA payload. Combining these enzymes with a CRISPR-Cas9 system that inserts the correct landing site would enable easy reprogramming of the powerful insertion system.

The new tool, PASTE (Programmable Addition via Site-specific Targeting Elements), includes a Cas9 enzyme that cuts at a specific genomic site, guided by a strand of RNA that binds to that site. This allows them to target any site in the genome for insertion of the landing site, which contains 46 DNA base pairs. This insertion can be done without introducing any double-stranded breaks by adding one DNA strand first via a fused reverse transcriptase, then its complementary strand.

Once the landing site is incorporated, the integrase can come along and insert its much larger DNA payload into the genome at that site.

Omar Abudayyeh, Drag-and-drop genome insertion of large sequences without double-strand DNA cleavage using CRISPR-directed integrases, Nature Biotechnology (2022). DOI: 10.1038/s41587-022-01527-4. www.nature.com/articles/s41587-022-01527-4

Comment by Dr. Krishna Kumari Challa on November 25, 2022 at 9:21am

Researchers suggest that wormholes may look almost identical to black holes

A group of researchers  has found evidence that suggests the reason that a wormhole has never been observed is that they appear almost identical to black holes.

They describe studying theoretical linear polarization from an accretion disk that would be situated around a class of static traversable wormholes and compared the findings to images of black holes.

For many years, scientists and science fiction writers have considered the theoretical possibility of a wormhole. Such an object, theory suggests, would take the form of a tunnel of sorts that connects two different parts of the universe. Moving through the tunnel would allow for travel to distant destinations in ways not available to spaceships incapable of moving faster than the speed of light—by taking a shortcut.

Unfortunately, no one has ever observed a worm hole or even any physical evidence that they actually exist. Still, because the theory for their existence is so strong, astrophysicists assume they do exist. The problem is that we either lack the technology to see them, or we have not been looking for them in the right way.

In this new effort, the researchers suggest that the latter is the problem. They have found evidence, via theory, that suggests that they might be sitting out there in the night sky in plain sight, and that the reason we are not seeing them is because we are mistaking them for black holes.

The work involved studying wormhole theories and then applying findings to the creation of simulations, with an emphasis on the polarity of the light that would be emitted by such an object—and by also taking account of the characteristics of an assumed disk surrounding its mouth. They then created both direct and indirect images to depict what a wormhole would look like and compared them to black holes; they found them to look remarkably similar.

The researchers noted that it should be possible to tell wormholes and black holes apart by noting subtle differences between them, such as polarization patterns and intensities and also their radii.

Valentin Deliyski et al, Polarized image of equatorial emission in horizonless spacetimes: Traversable wormholes, Physical Review D (2022). DOI: 10.1103/PhysRevD.106.104024

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 11:15am

This, in turn, could have a long-term impact on coasts and islands, which are already suffering greatly under the weight of sea-level rise and erosion from increasingly frequent and powerful storm surges.

Marlena Joppien et al, Nanoplastic incorporation into an organismal skeleton, Scientific Reports (2022). DOI: 10.1038/s41598-022-18547-4

Marlena Joppien et al, Microplastics alter feeding strategies of a coral reef organism, Limnology and Oceanography Letters (2022). DOI: 10.1002/lol2.10237

Part2

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 11:15am

Plastic in foraminifera and possible consequences for the environment

Single-celled organisms with calcareous shells, called foraminifera, contribute significantly to the formation of sand deposited on beaches, islands and coastal areas. Researchers  have now found for the first time that foraminifera can take up tiny plastic particles and incorporate them into their calcareous shells. The results were published in Scientific Reports and Limnology and Oceanography Letters.

Gleaming white tropical beaches are coveted destinations for many recreation-seekers. But how do we perceive such beaches if we have to fear that they consist to a not inconsiderable extent of micro- and nanoplastics—invisible to our eyes?

Tropical beaches are mainly formed by calcifying marine animals such as corals, mussels and snails. The fact that corals incorporate microplastics into their calcareous skeleton has already been proven in studies. In some regions of the world, however, such as Indonesia, the Philippines and Australia, many beaches consist largely of the calcareous shells of foraminifera. These are single-celled organisms, a few millimeters in size and with a protective calcareous shell, that can be found in warm, shallow coastal areas worldwide.

Foraminifera feed on, among other things, microalgae or organic material particles they find on the seafloor. Micro- and nanoplastic particles have similar sizes and could easily be mistaken for potential food.

In a series of experiments, the team exposed several hundred foraminifera to seawater tanks for several weeks. They fed them partly with tiny micro- or nanoplastic particles, partly with natural food particles or a mixture of both. They observed that while the foraminifera preferred the natural food, when both were available at the same time, they frequently ate plastic pieces.

Using a fluorescence microscope, the researchers were able to observe a large number of yellow glowing nanoplastic particles in the foraminifera. Although some of the unicellular organisms rejected the plastic after the feeding experiments, about half of the foraminifera retained the plastic load inside the cell.

After eight weeks, a scanning electron microscope with 80,000x magnification revealed that many of the single-celled organisms had already encrusted the plastic particles with a layer of calcium carbonate and were apparently in the process of incorporating them into their shell.

So if the plastic particles are small enough, the foraminifera will take them in as food. For the environment, this could have advantages and disadvantages. For example, the trillions of foraminifera on the seafloor could be a sink for nanoplastics, a system that removes plastic from the ocean.

One problem the researcher sees, however, is potential impacts on the health of the foraminifera. On beaches and in shallow marine areas, the shells of foraminifera are often deposited at high densities of more than 1 kg per m2. However, if the protozoa interchange plastic particles with their natural food and incorporate them into their calcareous shells, their fitness, shell formation and stability could be disrupted—with consequences for their population as a whole.
Part 1

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 10:33am

This is why the cell will identify ERV sequences and recruit dedicated repressive machinery to their sites and keep them silent. Additionally, the chromosome is getting compacted at these sites.

But what happens if you turn off these protective mechanisms? Chaos!

Vahid Asimi et al, Hijacking of transcriptional condensates by endogenous retroviruses, Nature Genetics (2022). DOI: 10.1038/s41588-022-01132-w

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 10:32am

Zombie viruses on a hijacking trip: Retroviral gene fragments affect embryonic cells

Ancient, dormant sequences in the genome impact embryonic development in unexpected ways. The mammalian genome contains retroviral sequences that are in an undead but mostly "harmless" state. An international research team recently discovered how some of these retroviral gene fragments affect embryonic cells if they are unleashed. Unexpectedly, not the viral proteins, but rather copies of the genetic material itself generate an imbalance in the cell.

Over thousands of years of evolution, countless viruses have embedded themselves in our genome. A staggering ten percent of mammalian genomes consist of ancient retroviral sequences. These no longer seem to pose any danger, because most of them have mutated beyond recognition. Additionally, these genes have been epigenetically silenced by the cell. But as the silencing of the viral remains fails, they will rise from their graves, causing chaos in the cell.

Researchers found that the messenger copies of some of the viral genes, the RNA, have an important impact on embryonic cells. The viral sequences seem to remember their original mission of hijacking the molecular machinery that ensures the flow of information from DNA to RNA to protein. Interestingly, the messenger RNA itself seems to be responsible.

Scientists  described that the RNA of the resurrected viruses exerts attractive forces on the enzymes that read the information from the DNA. The tasks of the embryonic cell—such as reading important embryonic genes—are neglected and a fatal imbalance develops. This unleashed state occurs, for example, in some types of cancer and neurological diseases.

Viruses are cleverly constructed snippets of genetic information. Some of them incorporate themselves into the genome of their hosts and persist there. Thousands of copies of Endogenous Retroviruses (ERVs) have spread throughout mammalian genomes, often in droves of hundreds of repetitive copies.

As retroviruses jump from one section of DNA to the next during their life cycle, they can alter genes and even recombine them. This makes them an important tool for evolution to create new genes. For an individual organism however, uncontrolled gene modification does not bode well, especially during embryonic development. 

Part 1

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 9:43am

Of these two species, the first is avoided by cattle and is used in traditional medicine as a pain reliever, sedative, and immune booster. The second is toxic for humans and cattle if eaten in great quantities. They also have nutritional value: fatty acids abound in corn poppy seeds, while the seeds of purple viper's bugloss are rich in edible oils.

The authors isolated water- and fat-soluble compounds from both species and determined their chemical identity with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (HPLC-MS). They focused on lipids, volatile essential oils, and alkaloids, produced by many plants as defense against herbivores. For example, they found that corn poppies are rich in bioactive alkaloids like rhoeadine, rhoeagenine, epiberberine, and canadine.

The authors then tested the activity of the isolated molecular fractions against three common parasites of birds: the protozoon Trichomonas gallinae, the nematode (parasitic worm) Meloidogyne javanica, and the fungus Aspergillus niger.

The results show that extracts from both plants are highly effective at inhibiting or killing protozoa and nematodes in vitro, while purple viper's bugloss is also moderately active against fungi.

The authors conclude that great bustards are prime candidates for birds that seek out specific plants to self-medicate. But more research is needed, they caution.The ultimate proof of self-medication requires experimental protocols developed in the biomedical, veterinary, and pharmacological sciences.

Luis M. Bautista-Sopelana et al, Bioactivity of plants eaten by wild birds against laboratory models of parasites and pathogens, Frontiers in Ecology and Evolution (2022). DOI: 10.3389/fevo.2022.1027201

Part 2

**

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 9:42am

World's heaviest flying bird may be self-medicating on plants used in traditional medicine

Do you think only humans can use plant based medicines based on experience? Then think again. Even animals can do this. Humans aren't the only species that self-medicates.

If you see a great bustard (Otis tarda) in the wild, you're unlikely to forget it. Massive, colorful, and impossible to mistake, they are the heaviest birds living today capable of flight, with the greatest size difference between the sexes. They are also "lek breeders," where males gather at chosen sites to put on an audiovisual show for the visiting females, who choose a mate based on his appearance and the quality of his showbirdship.

But now, a study in Frontiers in Ecology and Evolution suggests that great bustards have another claim to our interest: they actively seek out two plants with compounds that can kill pathogens. They may thus be a rare example of a bird that uses plants against disease—that is, self-medication.

Self-medication in animals is suspected to occur, with a lesser or greater degree of confidence, in animals as diverse as primates, bears, deer, elk, macaws, honeybees, and fruit flies. But it's tricky to prove beyond doubt in wild animals.

We can't compare between control and experimental treatments. And double-blind trials or dose-effect studies, obligatory steps in human or veterinary medicine, are obviously impossible in wild animals.

Great bustards breed on grasslands from western Europe and northwest Africa to central and eastern Asia. Approximately 70% of the world's population live in the Iberian peninsula. Females typically remain faithful to the home range where they hatched for life—10 to 15 years—while after dispersal, males revisit the same lake site year after year. By staying (and importantly, pooping) in the same area for prolonged periods, they risk re-infecting themselves. And males need exceptional stamina during the mating season, which is expected to cause their immune defenses to nose-dive.

In theory, both sexes of great bustards might benefit from seeking out medicinal plants in the mating season when sexually transmitted diseases are common—while males that use plants with compounds active against diseases might appear more healthy, vigorous, and attractive to females.

The  research team have studied great bustards since since the early 1980s, mainly in the regions of Madrid and Castille-Leon, Spain. They collected a total of 623 droppings from female and male great bustards, including 178 during the mating season in April. Under a microscope, they counted the abundance of recognizable remains (tissue from stems, leaves, and flowers) of 90 plant species that grow locally and are known to on the bustards' menu.

The results showed that two species are eaten by great bustards more often than expected from their abundance: corn poppies, Papaver rhoeas and purple viper's bugloss, Echium plantagineum.

"Great bustards select corn poppies and purple viper's bugloss mainly in the mating season , in April, when their energy expenditure is greatest. And males, who during these months spend much of their time and energy budgets on sexual display, prefer them more than females.

Part 1

Comment by Dr. Krishna Kumari Challa on November 24, 2022 at 7:36am

Major discovery about mammalian brains

In a new breakthrough to understand more about the mammalian brain, University of Copenhagen researchers have made an incredible discovery. Namely, a vital enzyme that enables brain signals is switching on and off at random, even taking hours-long "breaks from work". These findings may have a major impact on our understanding of the brain and the development of pharmaceuticals.

Millions of neurons are constantly messaging each other to shape thoughts and memories and let us move our bodies at will. When two neurons meet to exchange a message, neurotransmitters are transported from one neuron to another with the aid of a unique enzyme.

This process is crucial for neuronal communication and the survival of all complex organisms. Until now, researchers worldwide thought that these enzymes were active at all times to convey essential signals continuously. But this is far from the case.

Using an innovative method, researchers  have closely studied the enzyme and discovered that its activity is switching on and off at random intervals, which contradicts our previous understanding.

This is the first time anyone has studied these mammalian brain enzymes one molecule at a time, and we are awed by the result. Contrary to popular belief, and unlike many other proteins, these enzymes could stop working for minutes to hours. Still, the brains of humans and other mammals are miraculously able to function.

Dimitrios Stamou, Regulation of the mammalian-brain V-ATPase through ultraslow mode-switching, Nature (2022). DOI: 10.1038/s41586-022-05472-9

• ‹ Previous
• 1
• …
• 211
• 212
• 213
• 214
• 215
• …
• 844
• Next ›
• Page