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Comment by Dr. Krishna Kumari Challa on December 3, 2020 at 8:58am

Flightless birds more common globally before human-driven extinctions

There would be at least four times as many flightless bird species on Earth today if it were not for human influences, finds a study by researchers. The study, published in Science Advances, finds that flightlessness evolved much more frequently among birds than would be expected if you only looked at current species. 

Researchers say their findings show how human-driven extinctions have biased our understanding of evolution. 

Human impacts have substantially altered most ecosystems worldwide, and caused the extinction of hundreds of animal species. This can distort evolutionary patterns, especially if the characteristics being studied, such as flightlessness in birds, make species more vulnerable to extinction. We get a biased picture of how evolution really happens.

For the study, the researchers compiled an exhaustive list of all bird species known to have gone extinct since the rise of humans. They identified 581 bird species that went extinct from the Late Pleistocene (126,000 years ago) to the present, almost all of which were likely due to human influences.

The fossils or other records show that 166 of these extinct species lacked the ability to fly. Only 60 flightless bird species survive today.

Birds that cannot fly were much more diverse than previous studies had assumed, the study shows. The findings also confirm that flightless species were also much more likely to go extinct than species that could fly.

"Anthropogenic extinctions conceal widespread evolution of flightlessness in birds" Science Advances (2020). advances.sciencemag.org/lookup … .1126/sciadv.abb6095

https://phys.org/news/2020-12-flightless-birds-common-globally-huma...

Comment by Dr. Krishna Kumari Challa on December 3, 2020 at 8:53am

Continents prone to destruction in their infancy, study finds

Geologists have shed new light on the early history of the Earth through their discovery that continents were weak and prone to destruction in their infancy.

The Earth is our home and over its 4,500,000,000 (4.5 billion) year history has evolved to form the environment we live in and the resources on which we depend.

However, the early history of Earth, covering its first 1.5 billion years remains almost unknown and, consequently, poorly understood.

This was the time of formation of the first continents, the emergence of land, the development of the early atmosphere, and the appearance of primordial life—all of which are the result of the dynamics of our planet's interiors.

Reproducing the conditions of the early Earth in computer-generated numerical models, scientists showed that the release of internal primordial heat, three to four times that of the present-day, caused large melting in the shallow mantle, which was then extruded as magma (molten rock) onto the Earth's surface.

According to the researchers, the shallow mantle left behind by this process was dehydrated and rigid and formed the keels of the first continents.

These results explain that continents remained weak and prone to destruction in their infancy, ~4.5 to ~4.0 billion years ago, and then progressively differentiated and became rigid over the next billion years to form the core of our modern continents. The emergence of these rigid early continents resulted in their weathering and erosion, changing the composition of the atmosphere and providing nutrients to the ocean seeding the development of life.

Thermochemical lithosphere differentiation and the origin of cratonic mantle, Nature (2020). DOI: 10.1038/s41586-020-2976-3 , www.nature.com/articles/s41586-020-2976-3

https://phys.org/news/2020-12-continents-prone-destruction-infancy....

Comment by Dr. Krishna Kumari Challa on December 2, 2020 at 6:40am

Breaking the rules of chemistry unlocks new reaction

Scientists have broken the rules of enzyme engineering to unlock a new method for creating chemical reactions that could unlock a wide range of new applications—from creating new drugs to food production. They show a new method to produce chemical molecules more efficiently through a new one step reaction in the enzyme.

They have demonstrated how a very simple mutation in one of the key residues of a useful enzyme has dramatically expanded its synthetic scope, enabling the use of the mutant variant in the preparation of challenging chemical molecules, as well as natural metabolites that are vital in many biological processes in the body."

Any textbook on enzymes will report on how the catalytic amino acids in any given enzyme family are highly conserved, they are in fact a signature of the type of chemistry an enzyme can do. Variations do occur and in some cases, if the replacing amino acid is similar, both can be found in significant proportion in Nature, but others can be much less common and are found only in a limited number of species.

"In this study theyhave explored an untouched area of enzyme engineering and modified the a key catalytic residue in the active site of an enzyme. Previously it was thought that doing this would cause a loss of activity of the enzyme but we have found this is not the case when this biocatalyst is used in a synthetic direction and in fact challenging but very useful molecules can now be made under mild conditions which could be easily scaled up and replicated commercially for use in a wide range of products.

Martina L. Contente et al, A strategic Ser/Cys exchange in the catalytic triad unlocks an acyltransferase-mediated synthesis of thioesters and tertiary amides, Nature Catalysis (2020). DOI: 10.1038/s41929-020-00539-0

https://phys.org/news/2020-12-chemistry-reaction.html?utm_source=nw...

Comment by Dr. Krishna Kumari Challa on December 2, 2020 at 6:32am

Discovery shines light on how cancer cells could protect themselves

Researchers have found cancer cells can repair their DNA by using 'cables' in their nucleus. The findings open new possibilities for designing future cancer treatments. They  have made an unexpected discovery about cancer cells and how they harness 'cables' in a cell's nucleus to aid DNA repair and replication.

This discovery  revealed an unexpected function for the protein actin. Actin is well known as the protein that interacts with another protein called myosin to make muscles contract. Actin also forms cables inside cells that connect up and function like girders in a building, contributing to the structure and shape of cells.

While scientists have known for decades that actin plays this critical role in the main body of the cell, its role in the cell's control center, the nucleus, has been controversial.

For cancers to grow, cancer cells need to make many new copies of themselves. Every time this happens, the DNA in the cancer cells' nuclei must be replicated.

DNA replication in a cancer cell is like an old car traveling at its top speed—it frequently breaks down and has to get restarted. Cancer chemotherapy exploits this weakness in cancer cells by making the process break down even more frequently in an attempt to destroy them.

Researchers found that when cancer cells encounter problems replicating their DNA, actin cables form inside the nucleus. This allows the nucleus to change shape and increases the ability of the cancer cell to repair its DNA and restart the replication process.

Using advanced super resolution microscopy, the researchers showed that damaged DNA slides along the actin network to move to areas in the nucleus where repair occurs most efficiently. Scientists were previously unaware that cancer cells protected themselves in this way. Critically, this research found that actin performed these unexpected functions in response to treatment with chemotherapy and helped cancer cells resist the treatment.

Noa Lamm et al. Nuclear F-actin counteracts nuclear deformation and promotes fork repair during replication stress, Nature Cell Biology (2020). DOI: 10.1038/s41556-020-00605-6

https://medicalxpress.com/news/2020-12-discovery-cancer-cells.html?...

Comment by Dr. Krishna Kumari Challa on December 2, 2020 at 6:26am

AI predicts which drug combinations kill cancer cells

When healthcare professionals treat patients suffering from advanced cancers, they usually need to use a combination of therapies. In addition to cancer surgery, the patients are often treated with radiation therapy, medication or both.

Medication can be combined with drugs selected for specific cancer cells. Combinatorial drug therapies often improve the effectiveness of the treatment and can reduce the harmful side-effects if the dosage of individual drugs can be reduced. However, experimental screening of drug combinations is very slow and expensive, and therefore, often fails to discover the full benefits of combination therapy. With the help of a new machine-learning method, it is possible to identify the best combinations that selectively kill cancer cells with specific genetic or functional makeup.

developed a machine learning model that accurately predicts how combinations of cancer drugs kill various types of cancer cells. The new AI model was trained with a large set of data obtained from previous studies that investigated the association between drugs and cancer cells. "The model learned by the machine is actually a polynomial function familiar from school mathematics, but a very complex one. The model gives very accurate results. 

Heli Julkunen et al. Leveraging multi-way interactions for systematic prediction of pre-clinical drug combination effects, Nature Communications (2020). DOI: 10.1038/s41467-020-19950-z

https://medicalxpress.com/news/2020-12-ai-drug-combinations-cancer-...

Comment by Dr. Krishna Kumari Challa on December 2, 2020 at 6:17am

New device offers faster way to detect antibiotic-resistant bacteria

Bacterial infections have become one of the biggest health problems worldwide, and a recent study shows that COVID-19 patients have a much greater chance of acquiring secondary bacterial infections, which significantly increases the mortality rate.

Combatting the infections is no easy task, though. When antibiotics are carelessly and excessively prescribed, that leads to the rapid emergence and spread of antibiotic-resistant genes in bacteria—creating an even larger problem. 

One factor slowing down the fight against antibiotic-resistant bacteria is the amount of time needed to test for it. The conventional method uses extracted bacteria from a patient and compares lab cultures grown with and without antibiotics, but results can take one to two days, increasing the mortality rate, the length of hospital stay and overall cost of care.

To effectively treat the infections, we need to select the right antibiotics with the exact dose for the appropriate duration. There's a need to develop an antibiotic-susceptibility testing method and offer effective guidelines to treat these infections.

A new technique 's developed now that relies on the same principles as the batteries: Bacterial electron transfer, a chemical process that certain microorganisms use for growth, overall cell maintenance and information exchange with surrounding microorganisms. Researchers leverage this biochemical event for a new technique to assess the antibiotic effectiveness against bacteria without monitoring the whole bacterial growth.

A medical team would extract a sample from a patient, inoculate the bacteria with various antibiotics over a few hours and then measure the electron transfer rate. A lower rate would mean that the antibiotics are working.

"The hypothesis is that the antiviral exposure could cause sufficient inhibition to the bacterial electron transfer, so the readout by the device would be sensitive enough to show small variations in the electrical output caused by changes in antibiotic effectiveness. The device could provide results about antibiotic resistance in just five hours, which would serve as an important point-of-care diagnostic tool, especially in areas with limited resources.

Yang Gao et al, A simple, inexpensive, and rapid method to assess antibiotic effectiveness against exoelectrogenic bacteria, Biosensors and Bioelectronics (2020). DOI: 10.1016/j.bios.2020.112518

https://phys.org/news/2020-12-device-faster-antibiotic-resistant-ba...

Comment by Dr. Krishna Kumari Challa on December 1, 2020 at 1:13pm

How Bats Can Transmit Viruses | Virus Hunters

Comment by Dr. Krishna Kumari Challa on December 1, 2020 at 12:20pm

Scientists develop 'more accurate, fast Covid test' method to detect single virus particles

For identifying single virus particles, scientists have developed a new method based on changes in electrical current when they pass through ultrasmall pores, an advance which they claim may lead to new rapid coronavirus tests.

The study, which has been published in the journal ACS Sensors, demonstrated a new system for identifying single virus particles using an algorithm trained to detect changes in the current passing across silicon nanopores.

According to the scientists, including those from Osaka University in Japan, the work may lead to fast and accurate screening tests for diseases like COVID-19 and influenza.

In the new method, the scientists said a layer of the compound silicon nitride just 50 nanometres (nm) thick has tiny nanopores added.

The layer is suspended on a silicon wafer, they said, adding that when a voltage difference is applied to the solution on either side of the wafer, ions travel through the nanopores in a process called electrophoresis.

According to the study, the motion of the ions can be monitored by the current they generate, and when a viral particle enters a nanopore, it blocks some of the ions from passing through, leading to a transient dip in current.

Each dip reflects the physical properties of the particle, such as volume, surface charge, and shape, the scientists said, adding that this measure can be used to identify the kind of virus.

Using artificial intelligence (AI), the research team built a classification algorithm trained with signals from known viruses to determine the identity of new samples.

The scientists said the computer can discriminate the differences in electrical current waveforms that cannot be identified by human eyes, which enables highly accurate virus classification. By combining single-particle nanopore sensing with AI, scientists were able to achieve highly accurate identification of multiple viral species. The researchers believe coronaviruses are especially well suited for this technique since their spiky outer proteins may even allow different strains to be classified separately.

https://www.livemint.com/science/news/coronavirus-scientists-develo...

Comment by Dr. Krishna Kumari Challa on December 1, 2020 at 8:51am

Fingerprints' moisture-regulating mechanism strengthens human touch: study

Human fingerprints have a self-regulating moisture mechanism that not only helps us to avoid dropping things, but could help scientists to develop better prosthetic limbs, robotic equipment and virtual reality environments, a new study reveals.

Primates—including humans, monkeys and apes—have evolved epidermal ridges on their hands and feet with a higher density of sweat glands than elsewhere on their bodies. This allows precise regulation of skin moisture to give greater levels of grip when manipulating objects.

Fingerprints help to increase friction when in contact with smooth surfaces, boost grip on rough surfaces and enhance tactile sensitivity. Their moisture-regulating mechanism ensures the best possible hydration of the skin's keratin layer to maximize friction.

Primates have evolved epidermal ridges on their hands and feet. During contact with solid objects, fingerprint ridges are important for grip and precision manipulation. They regulate moisture levels from external sources or the sweat pores so that friction is maximized and we avoid 'catastrophic' slip and keep hold of objects. Understanding the influence of finger pad friction will help us to develop more realistic tactile sensors—for example, applications in robotics and prosthetics and haptic feedback systems for touch screens and virtual reality environments.

Ultrasonic lubrication is commonly used in touch screen displays that provide sensory 'haptic' feedback, but its effectiveness is reduced when a user has dry compared with moist finger pads. Moreover, being able to distinguish between fine-textured surfaces, such as textiles, by touch relies on the induced lateral vibrations but the absence of sliding friction inhibits our ability to identify what we are actually touching.

Fingerprints are unique to primates and koalas—appearing to have the dual function of enhancing evaporation of excess moisture whist providing a reservoir of moisture at their bases that enables grip to be maximized.

The researchers have discovered that, when finger pads are in contact with impermeable surfaces, the sweat from pores in the ridges makes the skin softer and thus dramatically increases friction. However, the resulting increase in the compliance of the ridges causes the sweat pores eventually to become blocked and hence prevents excessive moisture that would reduce our ability to grip objects.

Using hi-tech laser-based imaging technology, the scientists found that moisture regulation could be explained by the combination of this sweat pore blocking and the accelerated evaporation of excessive moisture from external wetting as a result of the specific cross-sectional shape of the epidermal furrows when in contact with an object.

These two functions result in maintaining the optimum amount of moisture in the fingerprint ridges that maximizes friction whether the finger pad is initially wet or dry.

Seoung-Mok Yum el al., "Fingerprint ridges allow primates to regulate grip," PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2001055117

https://phys.org/news/2020-11-fingerprints-moisture-regulating-mech...

Comment by Dr. Krishna Kumari Challa on November 30, 2020 at 11:05am

If the Earth is spinning all the time, why don’t things move around?

Curious Kids: If the Earth is spinning all the time, why don't things move around?

The Earth spins around its axis every day – but gravity keeps us firmly in place.

https://theconversation.com/curious-kids-if-the-earth-is-spinning-a...

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