Comment

Comment by Dr. Krishna Kumari Challa on January 19, 2023 at 11:51am

New study shows 'self-cleaning' of marine atmosphere

Scientists have shed new light on the "self-cleaning" capacity of the atmosphere.

This process of self-cleaning is essential to remove gaseous pollutants and regulate green house gasses such as methane from the atmosphere.

Researchers were already aware that the atmosphere had this "self-cleaning" ability, but in a new study, experts have now shown a new process that increases the ability of the marine atmosphere to self-cleanse.

Using a combination of aircraft and ground-based observations, scientists were able to confirm the widespread presence of nitrous oxide (HONO) in the remote Atlantic troposphere formed by so-called "renoxification", whereby photolysis of aerosol nitrate returns nitrogen oxides (NOx) and HONO to the marine atmosphere. Historically, aerosol nitrate had been considered a permanent sink for NOx. This new process could increase the ability of the atmosphere to self-cleanse on a global scale. Scientists say the findings, published in Science Advances, could be highly significant for atmospheric chemistry and largely reconcile widespread uncertainty on the importance of renoxification.

Importantly, the observations showed that the efficiency of renoxification increased with relative humidity and decreased with the concentration of nitrate." "This observation reconciled the very large discrepancies in the rates of renoxification found across multiple laboratory and field studies." "It was also consistent with renoxification occurring on the surface of aerosols, rather than within their bulk, a new and exciting finding with implications for how this fundamental process is controlled and parameterized in models." Recycling of nitrogen oxides on nitrate aerosol could have important, increasing, and as yet unexplored implications for the trends and distributions of atmospheric oxidants such as tropospheric ozone, an important greenhouse gas.

Simone Andersen et al, Extensive field evidence for the release of HONO from the photolysis of nitrate aerosols, Science Advances (2023). DOI: 10.1126/sciadv.add6266. www.science.org/doi/10.1126/sciadv.add6266

Comment by Dr. Krishna Kumari Challa on January 19, 2023 at 11:48am

The fundamental principles of DNA methylation thus appear highly conserved, enabling a deep look at the evolutionary history of vertebrates. However, this does not mean that DNA methylation remained unchanged over millions of years. The genetic code of epigenetics looks clearer and more prescriptive in vertebrates than in invertebrates, even though the underlying patterns are similar. And with the emergence of reptiles, birds, and mammals, the genetic determinants of DNA methylation become even more pronounced. It seems that complex animals including humans particularly depend on epigenetic protection of the genome through DNA methylation.

Large animals with a long lifespan should in theory have a higher risk of cancer, because their bodies consist of many more cells, and these cells have more time to develop into cancer cells. Yet elephants are no more likely to develop cancer than mice or trout. Scientists refer to this as Peto's paradox. The most plausible explanation is that large animals with a long lifespan have evolved special mechanisms that substantially reduce their cancer risk.

Results from the current study indicate that DNA methylation constitutes such a cancer-protective mechanism. Higher theoretical risk of cancer was generally associated with higher DNA methylation levels. This correlation was particularly evident in birds. Most birds have a low risk of cancer, even big birds with long lifespans such as eagles and penguins. The higher DNA methylation levels in large and long-lived birds may thus help protect them against cancer.

Overall, this study provides the most comprehensive analysis of epigenetics in its evolutionary context to date. It also establishes new methods for studying DNA methylation in diverse animal species. For many species, no high-quality genomes are yet available, which is why the team developed and optimized a method the analyze DNA methylation independently of any reference genomes.

This new method allows us to explore the interplay of genetics and epigenetics in all those animal species that were hardly accessible for epigenetic analyses. Hopefully, such evolutionary and comparative analyses will lead to a better understanding of epigenetics in humans, in diseases such as cancer, and in healthy aging.

Johanna Klughammer et al, Comparative analysis of genome-scale, base-resolution DNA methylation profiles across 580 animal species, Nature Communications (2023). DOI: 10.1038/s41467-022-34828-y

Part 2

**

Comment by Dr. Krishna Kumari Challa on January 19, 2023 at 11:45am

A molecular zoo of epigenetics

Our genes are encoded in the DNA sequence of the genome, which is highly similar across the diverse cell types of our body. Yet, each cell can only access those genes that are in an epigenetically permissive state. The epigenome thus provides a form of molecular access control to the genes—epigenetic "software" that protects our genetic "hardware" from activation in the wrong cells.

This layer of regulatory control has been essential for the development of complex organisms comprising of many hundred different cell types. Moreover, epigenetic regulation helps reduce our risk of cancer by protecting critical areas of the genome from accidental activation.

DNA methylation is the best known and arguably the most important epigenetic mechanism. Methyl groups (CH₃) mark those parts of the DNA that are to be tightly packaged and protected from faulty activation. DNA methylation has many roles throughout our lives—ranging from the fertilized egg to the adult organism, in diseases such as cancer and in the biological aging of our bodies.

DNA methylation provides the cells with epigenetic memory, ensuring that a liver cell always remains a liver cell and a heart cell always remains a heart cell—even though all cells in our body are equipped with the same genes.

DNA methylation is well-studied only in mammals, most notably in mice and humans. In a decade-long effort to fill critical gaps in our understanding of epigenetics, scientists from Bock's research group at CeMM have now mapped and analyzed DNA methylation profiles across 580 different animal species.

The data of the study data show that DNA methylation in animals followed very similar principles 500 million years ago as it does today.

Researchers looked at the relationship between DNA methylation and the underlying genetic DNA sequence in mammals, birds, reptiles, amphibians, fish and invertebrates. The patterns are very similar. For example, they were able to predict the distribution of DNA methylation in elephants genome using a model they  had created for the octopus. These epigenetic patterns therefore very likely existed in the last common ancestor of these animals, a very long time ago.

Part 1

Comment by Dr. Krishna Kumari Challa on January 19, 2023 at 10:37am

 How iron dysregulation might contribute to neurodegenerative diseases

Past neuroscience research consistently found a link between deviations from the "normal" iron metabolism, also known as iron dysregulation, and different neurodegenerative diseases, including Parkinson's disease (PD) and Multiple Sclerosis (MS). Specifically, brain regions associated with these diseases have been found to be often populated by microglia (i.e., resident immune cells) packed with Iron.

While the association between iron dysregulation and neurodegenerative diseases is well documented, the ways in which iron accumulation affects the physiology of microglia and neurodegeneration are yet to be fully grasped. Researchers  have recently carried out a study aimed at filling this gap in the literature, by better understanding how microglia respond to iron.

For years it has been known that iron accumulates in affected brain regions in PD, MS and other neurodegenerative diseases.

The key objective of the recent work  was to better understand how iron accumulation in microglia affects these cells' functioning and health. Their work builds on their previous studies, and on the 2012 discovery of an iron-dependent form of cell death, known as ferroptosis.

Ferroptosis is a form of cell death that is mediated by iron-dependent lipid peroxidation, a process that damages lipids by oxidizing them. In their paper, the researchers' hypothesized that iron-laden microglia are susceptible to ferroptosis and that this might play a role in neurodegenerative diseases.

To conduct their experiments, the researchers grew microglia in a tri-culture system. Using a series of genetic and experimental techniques, they then showed that these microglia are highly responsive to iron and also susceptible to ferroptosis.

In addition, the team showed that an overload of iron causes a shift in the microglial transcriptional state, which overlaps with a transcriptomic signature observed in microglia in brain tissue from deceased patients with PD. When they removed microglia from their tri-culture system, the researchers observed that iron-induced neurotoxicity in the system significantly slowed down. This suggests that microglia responses to iron overload play a crucial role in neurodegeneration.

Sean K. Ryan et al, Microglia ferroptosis is regulated by SEC24B and contributes to neurodegeneration, Nature Neuroscience (2022). DOI: 10.1038/s41593-022-01221-3

Jonathan D. Proto et al, Disrupted microglial iron homeostasis in progressive multiple sclerosis, bioRxiv (2021). DOI: 10.1101/2021.05.09.443127

Comment by Deepak Menon on January 19, 2023 at 5:53am

Dear Doctor Krishna - the years pass - I encountered your kkartlab in 2016 - thought I'd let you know that my son also completed his P Hd from Stanford in 2017 and set up his own Robotics Company soon after. https://www dexterity.ai
You never post your poetry here ... please do so - 'twill be nice
Cheers
Deepak Menon (Author on Amazon)

Comment by Deepak Menon on January 18, 2023 at 9:51pm

Aww - wonderful insights Dr Krishna.

Comment by Dr. Krishna Kumari Challa on January 18, 2023 at 11:35am

Unusual compound found in Rembrandt's The Night Watch

An international team of scientists from the Rijksmuseum, the CNRS, the ESRF the European Synchrotron, the University of Amsterdam and the University of Antwerp, have discovered a rare lead compound (named lead formate) in Rembrandt's masterpiece The Night Watch. This discovery, which is a first in the history of the scientific study of paintings, provides new insight into 17th-century painting technique and the conservation history of the painting. The study is published in Angewandte Chemie International Edition.

Comment by Dr. Krishna Kumari Challa on January 18, 2023 at 11:13am

Eating one wild fish same as month of drinking tainted water: study

Eating one freshwater fish caught in a river or lake in the United States is the equivalent of drinking a month's worth of water contaminated with toxic "forever chemicals", new research said recently.

The invisible chemicals called PFAS were first developed in the 1940s to resist water and heat, and are now used in items such as non-stick pans, textiles, fire suppression foams and food packaging.

But the indestructibility of PFAS, per- and polyfluoroalkyl substances, means the pollutants have built up over time in the air, soil, lakes, rivers, food, drinking water and even our bodies.

There have been growing calls for stricter regulation for PFAS, which have been linked to a range of serious health issues including liver damage, high cholesterol, reduced immune responses and several kinds of cancer.

To find out PFAS contamination in locally caught fish, a team of researchers analyzed more than 500 samples from rivers and lakes across the United States between 2013 and 2015.

The median level of PFAS in the fish was 9,500 nanogrammes per kilogram, according to a new study published in the journal Environmental Research.

Eating just one freshwater fish equalled drinking water with PFOS at 48 parts per trillion for a month, the researchers calculated.

Nadia Barbo et al, Locally caught freshwater fish across the United States are likely a significant source of exposure to PFOS and other perfluorinated compounds, Environmental Research (2022). DOI: 10.1016/j.envres.2022.115165

Comment by Dr. Krishna Kumari Challa on January 18, 2023 at 10:55am

Study finds that UV-emitting nail polish dryers damage DNA and cause mutations in cells

The ultraviolet nail polish drying devices used to cure gel manicures may pose more of a public health concern than previously thought. Researchers at the University of California San Diego have studied these ultraviolet (UV) light emitting devices, and found that their use leads to cell death and cancer-causing mutations in human cells.

The devices are a common fixture in nail salons, and generally use a particular spectrum of UV light (340-395nm) to cure the chemicals used in gel manicures. While tanning beds use a different spectrum of UV light (280-400nm) that studies have conclusively proven to be carcinogenic, the spectrum used in the nail dryers has not been well studied.

If you look at the way these devices are presented, they are marketed as safe, with nothing to be concerned about. But to the best of our knowledge, no one has actually studied these devices and how they affect human cells at the molecular and cellular levels until now.

Using three different cell lines—adult human skin keratinocytes, human foreskin fibroblasts, and mouse embryonic fibroblasts—the researchers found that the use of these UV emitting devices for just one 20-minute session led to between 20 and 30 percent cell death, while three consecutive 20-minute exposures caused between 65 and 70 percent of the exposed cells to die.

Exposure to the UV light also caused mitochondrial and DNA damage in the remaining cells and resulted in mutations with patterns that can be observed in skin cancer in humans.

Researchers observed multiple things:

DNA gets damaged,  some of the DNA damage does not get repaired over time, and it does lead to mutations after every exposure with a UV-nail polish dryer, exposure may cause mitochondrial dysfunction, which may also result in additional mutations.

The researchers caution that while the results show the harmful effects of the repeated use of these devices on human cells, a long-term epideomological study would be required before stating conclusively that using these machines leads to an increased risk of skin cancers. However, the results of the study were clear: The chronic use of these nail polish drying machines is damaging to human cells.

Maria Zhivagui et al, DNA damage and somatic mutations in mammalian cells after irradiation with a nail polish dryer, Nature Communications (2023). DOI: 10.1038/s41467-023-35876-8

Comment by Deepak Menon on January 17, 2023 at 9:41pm

Very interesting posts! As regards the use of human excreta for fertilizer - we have a soak pit system, and the municipality sends a tank to empty it by suction - I've never thought about what they do with it....?

• ‹ Previous
• 1
• …
• 386
• 387
• 388
• 389
• 390
• …
• 1036
• Next ›
• Page