Comment

Comment by Dr. Krishna Kumari Challa on September 2, 2023 at 12:03pm

Human ancestors nearly went extinct
Roughly 900,000 years ago, climate changes sweeping the globe might have pushed our distant ancestors to the brink of extinction. The unknown human-like species was reduced to just 1,280 breeding individuals, creating a genetic bottleneck that is still detectable in the DNA of modern-day humans. The population didn’t expand for more than 100,000 years, after which it bloomed again and the progenitors of our species and of our extinct relatives, the Denisovans and the Neanderthals, emerged.

The work, published in Science, suggests a drastic reduction in the population of our ancestors well before our species, Homo sapiens, emerged. The population of breeding individuals was reduced to just 1,280 and didn’t expand again for another 117,000 years.

About 98.7% of human ancestors were lost then.

The fossil record in Africa and Eurasia between 950,000 and 650,000 years ago is patchy and that “the discovery of this bottleneck may explain the chronological gap.

The researchers’ method allowed them to reconstruct ancient population dynamics on the basis of genetic data from present-day humans. By constructing a complex family tree of genes, the team was able to examine the finer branches of the tree with greater precision, identifying significant evolutionary events.

The technique put the spotlight on the period 800,000 to one million years ago — for which there is much unknown — in a way that hasn’t been done before.

Around 813,000 years ago, the population of pre-humans began to swell again. How our ancestors managed to survive, and what allowed them to flourish once more, remains unclear, though.

https://www.science.org/doi/10.1126/science.abq7487?utm_source=Natu...

Comment by Dr. Krishna Kumari Challa on September 2, 2023 at 11:54am

Groundwater depletion rates in India could triple in coming decades as climate warms, study warns

A new  study finds that farmers in India have adapted to warming temperatures by intensifying the withdrawal of groundwater used for irrigation. If the trend continues, the rate of groundwater loss could triple by 2080, further threatening India's food and water security.

Reduced water availability in India due to ground water depletion and climate change could threaten the livelihoods of more than one-third of the country's 1.4 billion residents and has global implications. India recently overtook China to become the world's most populous nation and is the second-largest global producer of common cereal grains including rice and wheat.

This is of concern, given that India is the world's largest consumer of groundwater and is a critical resource for the regional and global food supply.

Without policies and interventions to conserve groundwater, we find that warming temperatures will likely amplify India's already existing groundwater depletion problem, further challenging India's food and water security in the face of climate change.

 Nishan Bhattarai, Warming temperatures exacerbate groundwater depletion rates in India, Science Advances (2023). DOI: 10.1126/sciadv.adi1401. www.science.org/doi/10.1126/sciadv.adi1401

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 11:42am

Scientists Warn 1 Billion People on Track to Die From Climate Change

The fossil fuels that humanity burns today will be a death sentence for many lives tomorrow.

A recent review of 180 articles on the human death rate of climate change has settled on a deeply distressing number. Over the next century or so, conservative estimates suggest a billion people could die from climate catastrophes, possibly more.

As with most predictions for the future, this one is based on several assumptions.

One is a rough rule of thumb called the '1000-ton rule'. Under this framework, every thousand tons of carbon that humanity burns is said to indirectly condemn a future person to death.

If the world reaches temperatures 2°C above the average global preindustrial temperature, which is what we are on track for in the coming decades, then that's a lot of lives lost. For every 0.1 °C degree of warming from now on, the world could suffer roughly 100 million deaths.

If you take the scientific consensus of the 1,000-ton rule seriously, and run the numbers, anthropogenic global warming equates to a billion premature dead bodies over the next century.

Obviously, we have to act. And we have to act fast.

https://www.mdpi.com/1996-1073/16/16/6074

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 10:42am

COVID infection risk rises the longer you are exposed — even for vaccinated people

Rigorous evidence shows that significant contact with a person with SARS-CoV-2 is more likely to lead to transmission than a short encounter.

Prolonged exposure in close proximity to someone with COVID-19 puts people at high risk of catching the disease, even if they’ve had both the disease and vaccinations against it, a study shows.

The study, published this month in Nature Communications, reveals that the greater a person’s exposure to SARS-CoV-2, the more vulnerable they are to infection, regardless of their vaccination status. This relationship has long been suspected, but the study is one of the first to document it.

The findings point to the importance of masking, improved ventilation and other measures that reduce exposure to the virus.

Lind, M. L. et al. Nature Commun. 14, 5055 (2023)

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 9:40am

Boys who smoke in their early teens found to risk passing on harmful epigenetic traits to future children

A new study suggests boys who smoke in their early teens risk damaging the genes of their future children, increasing their chances of developing asthma, obesity and low lung function.

Research published in Clinical Epigenetics is the first human study to reveal the biological mechanism behind the impact of fathers' early teenage smoking on their children. Researchers  investigated the epigenetic profiles of 875 people, aged 7 to 50, and the smoking behaviours of their fathers.

They found epigenetic changes at 19 sites mapped to 14 genes in the children of fathers who smoked before the age of 15. These changes in the way DNA is packaged in cells (methylation) regulate gene expression (switching them on and off) and are associated with asthma, obesity and wheezing.

These studies have shown that the health of future generations depends on the actions and decisions made by young people today—long before they are parents—in particular for boys in early puberty and mothers/grandmothers both pre-pregnancy and during pregnancy.

Changes in epigenetic markers were much more pronounced in children whose fathers started smoking during puberty than those whose fathers had started smoking at any time before conception. Early puberty may represent a critical window of physiological changes in boys. This is when the stem cells are being established which will make sperm for the rest of their lives.

 Negusse Kitaba et al, Fathers' preconception smoking and offspring DNA methylation., Clinical Epigenetics (2023). DOI: 10.1186/s13148-023-01540-7

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 9:34am

Functionally, tumor-APCs engulfed and processed proteins and dead cells, secreted inflammatory cytokines, and cross-presented antigens to naïve CD8⁺ T cells. Human primary tumor cells could also be reprogrammed to increase their capability to present antigen and to activate patient-specific tumor-infiltrating lymphocytes.

What the team actually developed was a new way to lift the cloak of invisibility from cancer cells, which are infamously adept masters of disguise. When the researchers injected lab-treated tumor-APCs directly into established melanoma tumors in mice, they observed decreased tumor growth, improved responsiveness to immune checkpoint inhibition therapy, and increased survival rates among the animals.

 Olga Zimmermannova et al, Restoring tumor immunogenicity with dendritic cell reprogramming, Science Immunology (2023). DOI: 10.1126/sciimmunol.add4817

Part 2

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 9:33am

Scientists devise new way to eliminate cancer cells' evasion of immune system

Tumour cells are notoriously skilled masters of immune disguise and, in many ways, real-life versions of what it's like hiding under the fictional invisibility cloak.

But new research suggests that cancer cells can be forced to lose their invisibility and reveal their presence, factors that can help boost anti-cancer therapeutic activity and guarantee the death of tumor cells.

The new research, conducted by an international collaboration of scientists,  involved an elegant series of experiments in both human and animal cell lines. The research, still in the laboratory phase, is aimed at forcing cancer cells to reveal their antigens, the biomarkers on their surfaces. Once the antigens are revealed, aggressive immune forces can locate and destroy the cancer.

Cancer cells downregulate their antigen presentation molecules to maintain their invisibility—avoiding detection by immune cells. Prior research has focused on how to help immune cells better recognize tumor cells. The new investigation demonstrates that there might be another way to aid the immune system in overcoming cancer cell evasion: targeting the cancer cells themselves.

Decreased antigen presentation contributes to the ability of cancer cells to evade the immune system. So researchers  reprogrammed cancer cells in the lab, a change that transformed the cells into tumour-derived antigen-presenting cells—APCs. Once transformed, the cells were visible to the immune system. They used the minimal gene regulatory network of type 1 conventional dendritic cells to reprogram cancer cells into professional antigen-presenting cells, tumor-APCs.

The study lays the foundation for the development of immunotherapies that would allow reprogramming of cancer cells to antigen-presenting cells in situ.

The team of scientists borrowed a page from Mother Nature to arrive their unique way to peel away the invisibility cloak of tumor cells. In the blood exists a trio of cell types known as antigen presenting cells, or APCs. But this trio is not just any old group of three, they are known in the official biological nomenclature as professional APCs, and they include macrophages, B cells and dendritic cells. Their job as a professional APC (each has other important duties) is to present potentially dangerous antigens to T cells.

The multinational group of scientists demonstrated that cancer cells can be reprogrammed and made to cooperate in the business of making tumour antigens visible to killer T cells. Using transcription factors associated with antigen-presenting conventional type 1 dendritic cells, the team created tumor antigen-presenting cells in both mouse and human cancer cell lines. Once reprogrammed by way of transcription factors, these transformed cells were able to induce effective killer T cell activity. Reprogramming restored the expression of antigen presentation complexes and costimulatory molecules on the surfaces of tumour cells, allowing the presentation of endogenous tumour antigens on MHC-I [major histocompatibility complex-1] and facilitating targeted killing by CD8+ T cells.

Part 1

Comment by Dr. Krishna Kumari Challa on September 1, 2023 at 8:36am

What mummies reveal: The scents ancient Egyptians used

In an innovative endeavor to create a sensory bridge to the ancient past, a team of researchers has recreated one of the scents used in the mummification of an important Egyptian woman more than 3,500 years ago.

The research team found that the balms contained a blend of beeswax, plant oil, fats, bitumen, Pinaceae resins (most likely larch resin), a balsamic substance, and dammar or Pistacia tree resin.

Coined "the scent of the eternity," the ancient aroma will be presented at the Moesgaard Museum in Denmark in an upcoming exhibition, offering visitors a unique sensory experience to encounter firsthand an ambient smell from antiquity—and catch a whiff of the ancient Egyptian process of mummification.

The team's research centered on the mummification substances used to embalm the noble lady Senetnay in the 18th dynasty, circa 1450 BCE. The researchers utilized advanced analytical techniques—including gas chromatography-mass spectrometry, high-temperature gas chromatography-mass spectrometry, and liquid chromatography-tandem mass spectrometry—to reconstruct the substances that helped to preserve and scent Senetnay for eternity. Their research has been published in Scientific Reports.

Researchers analyzed balm residues found in two canopic jars from the mummification equipment of Senetnay that were excavated over a century ago by Howard Carter from Tomb KV42 in the Valley of the Kings.

These complex and diverse ingredients, unique to this early time period, offer a novel understanding of the sophisticated mummification practices and Egypt's far-reaching trade-routes.

The ingredients in the balm make it clear that the ancient Egyptians were sourcing materials from beyond their realm from an early date.

Among those imported ingredients were larch tree resin, which likely came from the northern Mediterranean, and possibly dammars, which come exclusively from trees in Southeast Asian tropical forests. If the presence of dammar resin is confirmed, as in balms recently identified from Saqqara dating to the 1st millennium BCE, it would suggest that the ancient Egyptians had access to this Southeast Asian resin via long-distant trade almost a millennium earlier than previously known.

 Barbara Huber, Biomolecular characterization of 3500-year-old ancient Egyptian mummification balms from the Valley of the Kings, Scientific Reports (2023). DOI: 10.1038/s41598-023-39393-y. www.nature.com/articles/s41598-023-39393-y

Comment by Dr. Krishna Kumari Challa on August 31, 2023 at 9:37am

Newly-engineered versions of bacterial enzyme reveal how antibiotics could be more potent

Modern medicine depends on antibiotics to treat infections by disabling targets inside bacterial cells. Once inside these cells, antibiotics bind to certain sites on specific enzyme targets to stop bacterial growth. Randomly occurring changes (mutations) in the genes for these targets occur naturally, in some cases making the target harder for the antibiotic to attach to, and that bacterial version resistant to treatment.

For this reason, the more antibiotics have been used over time, the greater the chances that bacterial populations will evolve to have mutants resistant to existing antibiotics, and the more urgent the call for new approaches to keep the treatments from becoming obsolete.

Researchers have for decades studied resistant mutants in hopes that related mechanisms would guide the design of new treatments to overcome resistance. The effort has been limited, however, because naturally occurring resistant mutants represent a small fraction of the mutations that could possibly occur (the complete mutational space), with most drug binding-site mutations to date having been overlooked.

To address this challenge, a new study by researchers to generate the full inventory of mutations in the bacterial species Escherichia coli where the antibiotic rifampicin attaches to and disables an essential bacterial enzyme known as RNA polymerase (RNAP).

The study authors created 760 unique RNAP mutants by replacing each of the 38 amino acid building blocks that make up the rifampicin binding site on E. coli with each of the 20 amino acid options present in nature. Growth of this mutant pool was then tested under different conditions, including treatment with rifampicin.

Published online August 30 in the journal Nature, the study found two mutants, L521Y and T525D, that are hyper-sensitive to rifampicin. Not only does the antibiotic prevent these mutants from growing, it nearly obliterates the mutant bacterial populations. This is a remarkable finding, say the authors, because rifampicin normally does not kill E. coli, or many other bacterial pathogens, but only stops their growth.

This work provides a map of antibiotic-bacterial RNAP interactions that will be of value to chemists working to build on the study effects by changing, not bacterial binding site residues, but instead the structure of rifampicin and other antibiotics so that they bind tighter for increased potency.

These techniques could be applied to map the binding sites of other drug types, and especially to those vulnerable to resistance.

Evgeny Nudler, High-resolution landscape of an antibiotic binding site, Nature (2023). DOI: 10.1038/s41586-023-06495-6. www.nature.com/articles/s41586-023-06495-6

Comment by Dr. Krishna Kumari Challa on August 31, 2023 at 8:52am

Sea sponge tissue found to hold bits of DNA from fish living around them

A team of environmental and marine biologists  has found that studying sea sponge tissue can reveal the nature of the fish community living around them. 

Sea sponges live on the ocean floor—once they pick a spot to call home, they anchor themselves to a base and remain fixed in that place for the rest of their existence. They survive by filtering nutrients and oxygen from ocean water as it moves through their porous tissue. They also emit waste.

In this new effort, the researchers  found that the water passing through sea sponge pores also carries DNA from fish that live in the area and that it becomes trapped in the sea sponges' tissues. This DNA provides a record of local biodiversity.

By classifying the fish that shed the DNA via sequencing, researchers were able to create a map of a given underwater ecosystem. They were able to discriminate assemblages by region of the ocean (from Svalbard to Western Greenland, for example) and the depth of the habitat and even the level of protection.

The researchers note that there is generally a high cost associated with conducting ocean biodiversity studies—collecting and studying sea sponges could offer a much cheaper option.

Trapped DNA fragments in marine sponge specimens unveil north Atlantic deep-sea fish diversity, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.0771. royalsocietypublishing.org/doi … .1098/rspb.2023.0771

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