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Comment by Dr. Krishna Kumari Challa on Saturday

Smells that deceive the brain: Research reveals how certain aromas are interpreted as taste

Flavored drinks without sugar can be perceived as sweet—and now researchers know why. A new study from Karolinska Institutet in Sweden, published in the journal Nature Communications, reveals that the brain interprets certain aromas as taste. The paper is titled "Tastes and retronasal odours evoke a shared flavour-specific neura...

When we eat or drink, we don't just experience taste, but rather a "flavor." This taste experience arises from a combination of taste and smell, where aromas from food reach the nose via the oral cavity, known as retronasal odor.

Researchers  have now shown that the brain integrates these signals earlier than previously thought—already in the insula, a brain region known as the taste cortex—before the signals reach the frontal cortex, which controls our emotions and behavior.

The taste cortex reacts to taste-associated aromas as if they were real tastes.

The finding provides a possible explanation for why we sometimes experience taste from smell alone, for example in flavored waters. This underscores how strongly odors and tastes work together to make food pleasurable, potentially inducing craving and encouraging overeating of certain foods.

The study results showed that aromas that are perceived as sweet or savory not only activate the same parts of the brain's taste cortex as the actual tastes but that they evoke similar patterns of activation. This overlap was particularly evident in the parts of the taste cortex that are linked to the integration of sensory impressions.

This shows that the brain does not process taste and smell separately, but rather creates a joint representation of the flavor experience in the taste cortex.

This mechanism may be relevant for how our taste preferences and eating habits are formed and influenced.

Putu Agus Khorisantono, et al. Tastes and retronasal odours evoke a shared flavour-specific neural code in the human insula, Nature Communications (2025). DOI: 10.1038/s41467-025-63803-6

Comment by Dr. Krishna Kumari Challa on Friday

Breathlessness increases long-term mortality risk, finds a study in Malawi

Research led by Liverpool School of Tropical Medicine and the Malawi-Liverpool-Wellcome Program shows that over half of hospital patients with breathlessness had died within a year of admission (51%), as opposed to just 26% of those without the symptom.

Most of these patients had more than one condition that caused breathlessness, including pneumonia, anemia, heart failure and TB.

The findings demonstrate the importance of integrated, patient-centered care, researchers say, to tackle the burden of high mortality for people with breathlessness, particularly in low-income countries. The work appears in Thorax.

Most of these patients live with more than one condition at the same time, which the researchers found to be a factor linked to higher mortality, such as those with TB or pneumonia. This suggests that treating diseases in isolation is not enough, and health care models that have traditionally focused on single presenting conditions may overlook important concurrent diseases.

Acute breathlessness as a cause of hospitalisation in Malawi: a prospective, patient-centred study to evaluate causes and outcomes, Thorax (2025). DOI: 10.1136/thorax-2025-223623

Comment by Dr. Krishna Kumari Challa on Friday

Medications leave lasting mark on gut microbiome, even years after use

Medications taken years ago can continue to shape the human gut microbiome, according to a large-scale study.

Analyzing stool samples and prescription records from over 2,500 Estonian Biobank participants in the Estonian Microbiome cohort, researchers found that the majority of drugs studied were linked to microbiome changes, with a substantial number of them also showing long-term effects detectable years after patients stopped taking them.

The impact was not limited to antibiotics: antidepressants, beta-blockers, proton pump inhibitors, and benzodiazepines all left microbial "fingerprints."

Most microbiome studies only consider current medications, but our results show that past drug use can be just as important as it is a surprisingly strong factor in explaining individual microbiome differences. 

This highlights that it is critical to account for drug usage history when studying links between the microbiome and disease. The research is published in the journal mSystems.

Interestingly, benzodiazepines—commonly prescribed for anxiety—had microbiome effects comparable to broad-spectrum antibiotics. The results also show that drugs from the same class that might be used for the same condition, e.g. diazepam and alprazolam, may differ in how much they disrupt the microbiome.

Follow-up samples from a subset of participants confirmed that starting or stopping certain drugs caused predictable microbial shifts, suggesting causal effects. Despite the small sample size of the second time-point analysis, the authors were able to verify long-term effects of proton pump inhibitors, selective serotonin reuptake inhibitors and antibiotics, such as penicillins in combination and macrolides.

Oliver Aasmets et al, A hidden confounder for microbiome studies: medications used years before sample collection, mSystems (2025). DOI: 10.1128/msystems.00541-25

Comment by Dr. Krishna Kumari Challa on Friday

DNA cassette tapes could solve global data storage problems

Our increasingly digitized world has a data storage problem. Hard drives and other storage media are reaching their limits, and we are creating data faster than we can store it. Fortunately, we don't have to look too far for a solution, because nature already has a powerful storage medium with DNA (deoxyribonucleic acid). It is this genetic material that researchers are using to create DNA storage cassettes.

DNA is the ultimate data storage solution because it is compact, dense and durable. It can hold an enormous amount of information in a microscopic space and preserve that data for thousands of years without needing electricity. Theoretically, the DNA in a single human cell has a capacity of approximately 3.2 gigabytes, which equates to roughly 6,000 books, 1,000 pieces of music or two movies.

Scientists have known about DNA's potential as a storage solution for a long time, but the challenge up until now has been to create a viable system that we can use. In a new study published in the journal Science Advances, researchers describe how they made a DNA cassette similar to cassette tapes that were staples in personal and car stereos in the 1980s.

The team first created the physical tape from a polyester-nylon blend. Then they printed barcode patterns on it to make millions of tiny, separate sections, similar to folders on a computer. This lets the system find the exact spot where the data is stored. Accessing information has been one of the problems of previous DNA storage techniques.
To store a file, digital data is first translated into a DNA sequence. The four bases, or building blocks of DNA (A, G, C, and T) act as a code, similar to the zeroes and ones that computers use. The researchers also coated the tape with a protective crystalline layer to protect the DNA bonds from breaking down.
Finally, they proved the system works by converting a digital image into DNA, then successfully and quickly retrieving it from the tape.

DNA cassette tape provides a strategy for fast, compact, large-scale DNA-based cold (infrequently accessed) or warm (needed on demand) data storage,  wrote the scientists in their paper.

Jiankai Li et al, A compact cassette tape for DNA-based data storage, Science Advances (2025). DOI: 10.1126/sciadv.ady3406

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:44pm

A review of 11 studies comparing donor-egg IVF to own-egg IVF found that donor-egg pregnancies had significantly higher rates of hypertensive disorders in the mother, as well as preterm birth and babies that were small for their gestational age.

A separate review focusing on preeclampsia in singleton IVF pregnancies found the condition occurred in 11.2% of donor-egg pregnancies, compared to 3.9% of own-egg pregnancies.

For women who can only become pregnant using a donor egg, these risks may be worth accepting. But it's important that women are made aware of the potential complications, especially if carrying twins, which further increases risks.

Women deserve full, unbiased information about the risks. That includes knowing that carrying someone else's egg may increase the likelihood of pregnancy complications. They can then make informed decisions about whether the potential benefits outweigh the risks.

Phoebe Barry et al, The outcomes of surrogate pregnancy using a donor egg compared to the surrogate's egg: a systematic review, Preprints (2025). DOI: 10.22541/au.174919886.60741282/v1

Part2

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:41pm

Donor-egg births may carry more risks

More women than ever are carrying babies conceived with someone else's egg—but few are told that this might carry greater health risks.

Pregnancies involving an embryo that doesn't share the pregnant woman's DNA are becoming more common. For many, it's a path to parenthood that would otherwise be closed.
But emerging evidence suggests that these pregnancies may come with higher rates of complications, including preeclampsia, gestational diabetes and preterm birth, and that women are often not given the full picture before treatment.

As the fertility industry expands and diversifies, it's time to ask whether patients are being adequately informed about the risks of carrying another woman's egg—and whether more caution is needed in how these options are presented.

There are three situations in which a woman may carry another woman's egg in her uterus.

The most common is when a woman cannot produce her own eggs but has a functioning uterus. In this case, donor eggs and in-vitro fertilization (IVF) offer the only route to pregnancy.

The other two situations involve fertile women carrying a donated egg on behalf of someone else. This happens in cases of gestational surrogacy, where a surrogate carries a baby genetically unrelated to her, or in reciprocal IVF, also known as ROPA or co-IVF. In the latter, one woman in a same-sex couple (or a trans man) donates her egg to her partner, so that both have a biological connection to the child.

In IVF, fertilization occurs outside the body and the resulting embryo is transferred into the uterus. But what happens when the egg in the uterus has no genetic similarity to the woman carrying it? Could this cause complications for her or the baby?

To answer that question, we need to compare outcomes in these situations to pregnancies where the egg shares approximately 50% of the mother's DNA, either through natural conception or own-egg IVF. Early evidence suggests that having someone else's egg in the uterus is associated with a higher risk of obstetric complications, including preeclampsia, gestational diabetes and preterm birth.

There are three key comparisons to make. First, donor-egg IVF v own-egg IVF. For infertile women using donor eggs, the most relevant comparison is IVF with their own eggs.
Second, gestational v traditional surrogacy. In gestational surrogacy, the surrogate carries a donor egg, while in traditional surrogacy, she uses her own. Outcomes can also be compared with the surrogate's previous natural pregnancies.

Third, reciprocal IVF v own-egg IVF. In same-sex couples, reciprocal IVF can be compared to own-egg IVF to assess risks.
Part1

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:26pm

The researchers propose that dysregulated estradiol levels induced by a high prevalence of C. innocuum could be the mechanism that links the gut microbiome to preterm birth.
The researchers note that because their study was based on two China-based cohorts with a relatively low prevalence of preterm birth, the findings may not be generalizable to other populations and should be authenticated by more work with them.

In the future, they hope to further elucidate the molecular mechanisms by which C. innocuum modulates preterm birth risk and potentially identify optimal intervention strategies to mitigate the bacteria's impact on pregnancy. They also seek to characterize the interaction between C. innocuum and host estrogen metabolism more generally, beyond pregnancy.

Maternal gut microbiome during early pregnancy predicts preterm birth, Cell Host & Microbe (2025). DOI: 10.1016/j.chom.2025.08.004. www.cell.com/cell-host-microbe … 1931-3128(25)00330-0

Part 2

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:19pm

Maternal gut microbiome composition may be linked to preterm births

Researchers have found that the presence of certain bacteria in the maternal gut microbiome during early pregnancy is linked to a higher risk of preterm birth. Published in the journal Cell Host & Microbe on September 10, the study reports that one particular species, Clostridium innocuum (C. innocuum), contains a gene that can degrade estradiol—an important pregnancy hormone.

This study suggests that for pregnant women or women preparing to become pregnant, it may be important to monitor their gut microbiome to prevent potential adverse pregnancy outcomes.

The researchers used samples and data from two large pregnancy cohorts—the Tongji-Huaxi-Shuangliu Birth cohort from southwest China and the Westlake Precision Birth cohort from southeast China.
For the first cohort, the team collected stool samples from 4,286 participants in early pregnancy, at an average of 10.4 gestational weeks. For the second cohort, they collected stool samples from 1,027 participants in mid-pregnancy, or around 26 gestational weeks. They also collected blood samples from all participants, which were used to measure human genetic variations and hormone metabolism.

After working with the first cohort, the researchers were able to establish a comprehensive database containing rRNA-based microbial genera data, metagenome-based species data, and phenotype data such as preterm delivery status.

They used several statistical models to screen the annotated gut microbial genera and species and their relationship to preterm birth status or gestational duration .Through that work, they identified 11 genera and 1 species that had a statistically significant link.

The results, which were validated with the second cohort, showed that bacterial species C. innocuum—a small, rod-shaped bacteria—had the strongest connection to preterm birth. Further study of C. innocuum revealed that this species makes an enzyme that degrades estradiol—a form of estrogen that plays a pivotal role during pregnancy.

Estradiol regulates critical pathways that sustain pregnancy and initiate the process of childbirth.

Part1

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:14pm

Climate change is driving fish stocks from countries' waters to the high seas, study finds

Fish and other marine organisms, though deeply affected by human activities, don't respect human borders. The ranges of many commercially important species in fact straddle the borders of countries' exclusive economic zones (EEZs) and international waters, known as the high seas. This arrangement, which makes fisheries management difficult, is set to get even more complicated as climate change continues to heat up the ocean, a new study says.

The study, published July 30 in the journal Science Advances, found that more than half of the world's straddling stocks will shift across the maritime borders between EEZs and the high seas by 2050. Most of these shifts will be into the high seas, where fisheries management is much more challenging and stocks are more likely to be overexploited.

Juliano Palacios-Abrantes et al, Climate change drives shifts in straddling fish stocks in the world's ocean, Science Advances (2025). DOI: 10.1126/sciadv.adq5976

Kamal Azmi et al, Putting Regional Fisheries Management Organisations' Climate Change House in Order, Fish and Fisheries (2025). DOI: 10.1111/faf.70015

Comment by Dr. Krishna Kumari Challa on September 11, 2025 at 1:00pm

'Potential biosignatures' found in ancient Mars lake

A new study suggests a habitable past and signs of ancient microbial processes on Mars. Led by NASA and featuring key analysis from Imperial College London, the work has uncovered a range of minerals and organic matter in Martian rocks that point to an ancient history of habitable conditions and potential biological processes on the Red Planet.

This is a very exciting discovery of a potential biosignature but it does not mean we have discovered life on Mars. We now need to analyze this rock sample on Earth to truly confirm if biological processes were involved or not.

While driving through the valley, called Neretva Vallis, Perseverance came across a thick succession of fine-grained mudstones and muddy conglomerates. Here, it conducted a detailed analysis of these rocks, using instruments such as the Planetary Instrument for X-ray Lithochemistry (PIXL) and Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC).

By mapping the types and distributions of different sedimentary rocks, researchers were able to reconstruct the environment in which these mudstones were deposited.

Their analysis revealed a range of sedimentary structures and textures indicative of lake margin and lake bed environments, including a composition rich in minerals like silica and clays—the opposite to a river scenario, where fast-moving water would carry these tiny particles away.

This pointed to a surprising conclusion: they had found lake deposits in the bottom of a river valley.

The finding may suggest a period in the history of Jezero Crater where the valley itself was flooded, giving rise to this potentially habitable lake.

With the lake habitat scenario pinned down, the Perseverance science team turned their attention to the mudstones themselves. It was inside these rocks that they discovered a group of tiny nodules and reaction fronts, with chemical analysis revealing that these millimeter-scale structures are highly enriched in iron-phosphate and iron-sulfide minerals (likely vivianite and greigite).

These appear to have formed through redox reactions involving organic carbon, a process that could have been driven by either abiotic or—interestingly—biological chemistry. Importantly, this sets the stage for everything that happened next: the formation of this specific type of oxidized, iron- and phosphorus-rich sediment was the essential prerequisite for creating the ingredients for subsequent reactions.

Since these ingredients mirror by-products of microbial metabolism seen on Earth, it can be considered a compelling potential biosignature, raising the possibility that there was once microbial life on Mars.

Ultimately, the only way for the true origin of these structures to be determined is by returning the samples to Earth, a possibility that rests on when future missions will manage to successfully collect the samples from Mars' surface.

Joel Hurowitz, Redox-driven mineral and organic associations in Jezero Crater, Mars, Nature (2025). DOI: 10.1038/s41586-025-09413-0. www.nature.com/articles/s41586-025-09413-0

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