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Medscape
a day ago
- General
- Medscape
How Today's Human Brain Became so Uniquely Human
What unique processes conspire to create a healthy, functional human brain? How can we be so genetically similar to, say, chimpanzees, and yet be light-years more sophisticated cognitively and behaviorally? It may just come down to six cells. Evolutionary biologists who study the human brain and explore questions about why we're so different from other primates are especially interested in the contrasts between humans and chimpanzees. 'We share more than 99% of our DNA with chimpanzees, yet the human and chimpanzee brains are unique. That difference has always been very fascinating to me,' said Soojin Yi, PhD, professor in the Department of Ecology, Evolution, and Marine Biology at the University of California, Santa Barbara. Yi and colleagues recently published findings in the Proceedings of the National Academy of Sciences ( PNAS ) that help deepen scientists' understanding about what's behind our brain differences. They've found that 'there is more differential gene expression in human brains,' said Yi, referring to the activation of different genes within a single brain cell type that defines that cell's purpose. What's more, she said, 'Different brain cells follow different evolutionary paths depending on their unique roles in the brain.' New Findings While previous studies have suggested that human brain evolution is linked to accelerated changes in gene expression, Yi said many questions still remain. To explore how genes in different types of human brain cells have evolved compared with those of chimpanzees, the researchers used single-cell human and nonhuman primate (chimpanzee and rhesus macaques) transcriptomic data — messenger RNA transcripts present in a specific cell type — to analyze the unique molecular profiles (the gene activity) of six brain cell types. Yi said many single-cell research approaches had focused primarily on neurons, with relatively small numbers of nonneuronal cells, so their team aimed for a more diverse approach. 'To balance the brain cellular heterogeneity and statistical rigor,' she said that in addition to looking at excitatory and inhibitory neurons, they also looked at four glial cell types — astrocytes, microglia, oligodendrocytes, and oligodendrocyte precursor cells. Each of these cell types plays an important role in brain function and health. For example, excitatory neurons transmit signals between brain regions, inhibitory neurons help control brain activity, oligodendrocytes contribute to the formation of the myelin sheath around nerve fibers, and microglia are the brain's immune cells, always on the prowl for pathogens. Star-shaped astrocytes play a variety of roles, including maintaining the blood-brain barrier and supporting neurons. What They Learned 'Compared to chimpanzee brains, the human brain showed significant signs of accelerated regulatory evolution across all of the six major cell types in the brain,' said Yi, explaining that certain genes in human brain cells have evolved to produce more of certain proteins at a faster rate than in other primates. 'It's much more extensive than previously believed,' she said. Of the 25,000 genes involved in their analysis, Yi and colleagues were able to identify differences in the expression of about 5%-10% of the genes. When they considered cell subtypes, differences in expression leapt to 12%-15%. While the researchers expected to see more regulation than what was seen in previous studies, as well as some kind of cell-type specificity, Yi said, 'We didn't expect as much cell-type specificity as we saw.' 'What was really interesting to me was that when you compared cell types, genes that are differentially expressed in microglia are very different than genes that are differentially expressed in neurons,' said Yi. The findings support the belief held among many other researchers that there is 'a tremendous amount of diversity' among even the same types of brain cells in one part of the brain compared with another, Yi said. 'You may have the same cell type [such as a neuron], but it looks a little bit different in terms of transcript profiles depending on where it is located in the brain. I think that we cannot look at the brain from just a molecular perspective. We've got to really appreciate that the brain is an amalgam of many different cell types doing their own things while also working together to do these very complex functions that our brains are capable of,' said Yi. The authors pointed out study limitations, including the fact that data from nonhuman primates came from individuals living in captive facilities, which could affect their transcriptional profiles. Another Perspective In André Sousa's lab at the University of Wisconsin-Madison, the assistant professor of neuroscience and his colleagues study human brain development and evolution. 'We try to understand the mutations that have accumulated in human DNA after our split from our closest lineage — chimpanzees, bonobos, and gorillas — that can alter gene expression,' he said. Sousa, who was not involved in the PNAS study, said the new research adds another piece to the puzzle. 'I don't think it's an 'aha moment' in the sense that several studies before this had shown this abundance of genes that are more expressed in the human brain. But most of those studies were done at the bulk tissue level. The brain is very heterogeneous, and in bulk tissue studies, you can be diluting lots of signals,' he said. Because the new study analyzed single cells, he said, 'they found way more differentially expressed genes than previous studies. And we need to be a little bit careful because it could be a bias from the methodology because when you are analyzing single cells, you increase your statistical power.' Sousa said the results of the study left him pondering the fact that 'in general, more genes are more expressed both in chimpanzees and humans than genes that are lower expressed.' And that's interesting. 'I've been thinking about it quite a lot. Why do we see more genes going up than down in all of these species? We still don't know very much about what it means. It's hard to understand what's happening because it's very complex. It can have a lot of justifications, both molecularly, what's happening in the DNA, but also evolutionarily, what are the constraints that allow a gene to be more or less expressed?' he said. Sousa said he also found it interesting that the researchers subdivided certain cell types into subgroups. 'Even within subtypes, they saw accelerated evolution in terms of more upregulated genes in humans and chimpanzees than downregulated ones, and what the interesting thing they see is that the genes that are differentially expressed in each cell tend to be different. So they speculate that that probably reflects functional specialization of these cells in these species. It's a potential explanation. But it's impossible to know for sure from this data set and will require more research,' said Sousa. The authors hope to continue studying differential gene expression at the cellular level in both human and primate brains, especially the brain cell subtypes. But Yi said as scientists continue to piece together clues to what makes today's human brain so uniquely human, all animal brain evolution is fascinating. 'There are other species with awesome brains that are doing all these special things, too,' she said.
Time of India
4 days ago
- Health
- Time of India
Amdavadi scientist at Yale aims to combat AMR bacteria using viruses
Ahmedabad: Taking a cue from ancient wisdom – an enemy's enemy is a friend — an associate research scientist from Yale University, with his roots in the city, is working on improving the virus-bacteria interaction to use viruses known as bacteriophages to kill bacteria. Tired of too many ads? go ad free now Dr Jyot Antani is part of the team that aims to further the science of targeting specific bacteria that have developed antimicrobial resistance (AMR) due to which the infection they cause cannot be treated with conventional antibiotics. The study, 'Microscopic Phage Adsorption Assay: High-throughput Quantification of Virus Particle Attachment to Host Bacterial Cells,' by Antani, Timothy Ward, Thierry Emonet, and Paul Turner from Yale University, was published recently in the Proceedings of the National Academy of Sciences (PNAS) journal. "Like humans, bacteria can also be infected by viruses. They bind to the receptors on a bacterial host cell and replicate in a process identified as lytic replication, where the host's resources are used to create more phages. This causes the cell to rupture and die," explains Antani. Globally, these mechanisms are being reviewed as a potential way to address AMR bacterial infections through phage therapy. However, one roadblock is understanding this unique interaction at the microscopic level. The traditional method involves mixing bacteria and viruses in a flask and testing the mixture sample at regular intervals to measure the attachment of the phage (virus) on bacteria. It is time-consuming, labour-intensive and provides only an estimation, said researchers. Antani's team from the Yale Quantitative Biology Institute worked on the problem to develop the Microscopic Phage Adsorption (MPA) assay. Tired of too many ads? go ad free now The published work indicates that the method quantifies the interaction between bacteria and phage at individual levels. "Using fluorescent dye, the phages appear as bright spots against the background of bacteria. Using this technique, researchers can record videos of the phages and bacteria in real time, documenting the dynamic movements and individual attachments of phages to bacteria," read the research summary on the Yale University website, Yale Scientific. Antani said that the breakthrough will help researchers understand the impact of different phage types on bacteria and develop strategies to combat bacteria. "If the sample shows a stable fluorescent dot (phage), it means that it got strongly attached to host bacteria. Phages bind to specific molecules (proteins or sugars) that stick out from the bacterial surface, like a ship docking into its assigned spot in the harbour," he said. "We tried many different species of each, including some notorious bacteria known for becoming resistant to antibiotics. Our approach successfully worked for most phages and bacteria that we tested." Antani's journey from Ahmedabad to New Haven has been inspiring. He studied in Gujarati medium until Class 12 before gaining admission to IIT Bombay where he pursued chemical engineering. He received a scholarship for his PhD at Texas A&M University, where he studied the movement of bacteria. "The Covid and post-Covid phases motivated me to explore the interaction between bacteria and viruses, and I got the postdoctoral opportunity at Yale University," he adds. "There are several interesting projects going on in India in this field, too."
CNET
7 days ago
- Business
- CNET
Use AI at Work? Your Coworkers May Be Judging You
Bosses everywhere are saying generative AI is the future. The signals emanating from the C-suites of corporations big and small are clear: If artificial intelligence doesn't take your job, it will at least change it significantly. The catch: If you use AI at work, your coworkers and maybe even your managers may think you're lazy. That is if you can get hired in the first place. This is the finding of a new study by researchers at Duke University published this month in the journal PNAS. Across four studies, the researchers examined whether people who used AI at work worried others would see them as lazy or incompetent and whether those fears were valid. "We found there was this universal social evaluation penalty where people described as using AI are evaluated as being less competent, less diligent, lazier than people who are described as receiving help from all sorts of other searches," Jessica Reif, a Ph.D. candidate at the Duke University Fuqua School of Business and lead author of the study, told me. The study highlights the difference between the hype over AI at work and the reality on the ground. Although business leaders and AI companies can't stop themselves from envisioning a utopian AI future in which autonomous agents do most of the work and humans focus on truly creative tasks, workers are skeptical. That skepticism — only 23% of American adults said they expect AI will improve how people do their jobs in a recent survey by Pew — affects how people view coworkers who use these tools. People worry they are judged for using AI The Duke University team first looked at whether employees would hesitate to admit they use an AI tool relative to a non-AI tool. The first of four studies found the 500 online participants were more likely to believe they would be judged by a manager or colleague as being lazy, replaceable or less competent if they said they use a generative AI tool versus a non-AI tool. The second test confirmed it. The 1,215 participants read a paragraph about an employee and rated how lazy, competent, diligent, ambitious, independent, self-assured or dominant they perceived the person to be. The people being rated were described as either receiving help from generative AI (like a lawyer using a tool to summarize information) or non-AI sources (like a paralegal) or were in a control group with no statement about help. People who received AI help were seen as more lazy, less competent, less diligent, less independent and less self-assured than either the control group or those receiving non-AI help. The case of a lawyer getting help from AI versus a paralegal is just one example. The researchers used 384 different scenarios, with different jobs and types of help. "What we found is that this was pretty consistent across all the occupations we queried," Reif said. In their third study, the researchers had 1,718 participants serve as "managers" to hire someone for a task. Some of the "candidates" were reported as using AI regularly, and some were people who never use AI. The managers were also asked about their own AI use. Managers who use AI regularly were more likely to see candidates who use AI as a good fit, while those who don't usually preferred candidates who don't. The third study was unclear about whether AI would actually be helpful for the task, so in the final study, participants were asked to imagine they were hiring a gig worker for a task. They were then asked to evaluate workers who either used AI tools or non-AI tools and rate how they would perceive them for manual tasks or digital tasks. The results found that while people who used AI were seen as more lazy, that perception is reduced if the evaluator uses AI or if AI is clearly useful for the task. But just because there isn't a penalty doesn't mean there's an advantage, perception-wise, for AI users in that last study, according to Richard Larrick, one of the authors and a professor of management at Duke University. "The people themselves who are heavy AI users don't actually kind of give any particular benefit or reward, in terms of their perceptions, to the AI user," Larrick said. "So it isn't like there's some boost in perceptions when high AI users think about another AI user. It's just that you wipe out for them the laziness perception." Your CEO may think AI is the future Ever since large language models like ChatGPT burst onto the scene in 2022, management consultants and corporate executives have been touting generative AI as the next big thing in the workplace. Workplace apps from companies like Google and Microsoft seem more packed each day with new AI functions and prompts. As the technology has matured a bit and more useful applications have arisen, that perception has only gotten stronger for many companies. Shopify and Duolingo, for instance, both recently announced they would prioritize AI-driven work and try to see if an AI can do a job before hiring a new employee or contractor. A commandment from a CEO to be AI-first is one thing. Actually changing the culture in your workplace and among the people you work around is entirely different. "I think there are cases where, when the rubber meets the road implementing tools like generative AI, there are challenges," Reif said. "What we're showing is just one such challenge of many." She speculated as more employers, especially tech-savvy ones, prioritize AI use and skills, the social costs will drop eventually. "I think it's going to take a while for this penalty to really go away," she said. Larrick said that even if general perceptions around AI users change, the social penalty may only disappear for certain tasks. For some work, using generative AI will be more acceptable. For others, it won't. How to avoid judgment from coworkers One way not to be judged at work is not to use AI on the job. And that may be what people are doing already, just based on the simple fact that people will judge you, as the researchers found in their first study. "As long as my choice of adopting AI is based on my theory of what others will think, even as what other people think changes, if my theory doesn't change fast enough, I still might be reluctant to use it and to reveal it," Larrick said. Another way to deal with the perception of laziness is to point out whether AI is saving you time and whether the time you save is being used well, Reif said. Perceived laziness isn't the only problem with using generative AI at work. There are concerns about whether the work you ask it to do is accurate or competent. So be sure you're checking your work and show that you are, in fact, using skills that can't be easily replaced, said Jack Soll, one of the authors and a professor of management at Duke University. "The more that employees can make their peers and their bosses understand that it takes skill and knowledge in order to use it appropriately, I think others can then appreciate their AI use," he said.
Yahoo
29-05-2025
- Health
- Yahoo
Blood-Brain Barrier 'Guardian' Shows Promise Against Alzheimer's
A new drug targeting inflammation in the brain has been shown to bolster the blood-brain barrier in mice, pioneering a potential shift in the fight against neurodegenerative diseases like Alzheimer's. "Finding [the drug] blocks brain inflammation and protects the blood-brain barrier was an exciting new discovery," says pathologist Sanford Markowitz from Case Western Reserve University (CWRU). What's more, the researchers note that amyloid levels – the abnormally clumping proteins traditionally thought to play a role in the progress of Alzheimer's – remained the same. This suggests the new treatment, focusing on an immune protein called 15-PGDH, targets a completely different physiological pathway than many existing medications. "This is important because the most recently approved Alzheimer's drugs focus only on removing amyloid and, unfortunately, don't work very well and have risky side effects," explains Markowitz. "Inhibiting 15-PGDH thus offers a completely new approach for Alzheimer's disease treatment." The blood-brain barrier is a layer of tissue that any substance entering the brain via the blood must pass through. When intact, the barrier filters out potential dangers such as toxins, bacteria, and viruses. Traumatic brain injury can damage this barrier, increasing risks to brain cells. Such blood-brain barrier deterioration has also been identified as a possible early indicator of dementias like Alzheimer's. By investigating the molecules active within the blood-brain barrier cells, CWRU physiologist Yeojung Koh and colleagues were able to identify that the immune enzyme 15-PGDH was elevated in both mice and humans with neurodegeneration arising from age, injury, or disease. In response, the researchers developed SW033291; a compound that can block the enzyme's activity. The medication was found to successfully protect the blood-brain barrier in mice and prevent cognitive impairment even after traumatic brain injury. "In these mouse models treated with the drug, the blood-brain barrier remained completely undamaged," says neuroscientist Andrew Pieper, also from CWRU. "The brains didn't undergo neurodegeneration and, most importantly, cognition and memory capacity were completely preserved." With almost 10 million new global cases of dementia yearly, an increasing number of people face cognitive decline, either personally or in loved ones. And despite decades of research, treatment outcomes remain unclear. Exploring new tactics like this is essential to improving lives, but there's still a long way to go. "Our findings establish 15-PGDH as a guardian of blood-brain barrier integrity… and a compelling target for protection from neurodegenerative disease," Koh and team write in their paper. This research was published in PNAS. Anti-Aging Cocktail Extends Mouse Lifespan by About 30 Percent Sudden Death Among Professional Bodybuilders Raises Health Concerns Microbe From Man's Wound Able to Feed on Hospital Plastic
News18
27-05-2025
- Health
- News18
Why Are Men Taller Than Women? Science Has The Answer
Last Updated: A recent study examining genetic information from almost one million individuals has helped explain why men tend to be taller than women. On average, men tend to be about five inches taller than women. Although hormones have traditionally been the main reason for this, recent studies highlight the influence of genetics, especially sex chromosomes, as a key factor behind this persistent height difference. A thorough study featured in the Proceedings of the National Academy of Sciences (PNAS) examined genetic information from close to one million adults. Researchers utilised data from three major sources: the UK Biobank and two U.S.-based biobanks—MyCode and All of Us. Out of the 928,605 participants, 1,225 were found to have an unusual number of sex chromosomes, offering a unique perspective on the biological factors that impact height. What the SHOX Gene Does The study focuses on the SHOX gene, which is essential for determining height. This gene is found in a region called PAR1—pseudoautosomal region 1—that exists on both the X and Y chromosomes, allowing it to act similarly regardless of which sex chromosome it's on. In females (XX), one X chromosome is mostly inactive, but genes in the PAR1 region, like SHOX, still work a little, though not fully. In males (XY), both the X and Y chromosomes use the SHOX gene completely, leading to higher activity of the gene. By studying people with different numbers of sex chromosomes, like extra X or Y chromosomes, the researchers discovered that having an extra Y chromosome had a bigger impact on height than an extra X chromosome. This finding was consistent across various ancestry groups, showing a clear genetic effect on how tall someone is. To understand how these chromosome differences affect height, the researchers used a statistical method called multivariate linear regression. This helped them consider factors like hormones, inactive chromosomes, and disorders such as Klinefelter and Turner syndromes. Their results showed that genetics from the Y chromosome accounts for a large part—up to 22.6 per cent—of the average height difference between men and women. Matthew Oetjens, the lead researcher from Geisinger College of Health Sciences, highlighted the important role of the SHOX gene. He explained that because SHOX is located near the end of the sex chromosomes, it avoids being fully silenced in females, but only to some extent. In males, both the X and Y chromosomes work together to increase the genes' activity, which influences greater height. New Insights Although the SHOX gene explains about a quarter of the average height difference between men and women, scientists think other factors like sex hormones and unknown genes also contribute. Eric Schadt, a professor at Mount Sinai School of Medicine, said that using large biobank data helped solve a long-standing mystery. He added that while the gene's impact is small, it's an important step toward better understanding how humans grow. Previous studies have found that over the last hundred years, men's height has increased faster than women's, making the difference between them even bigger. Social research also shows that women usually prefer taller men as partners. However, scientists warn that being taller might come with a higher risk of some cancers because taller people have more cell growth. These findings improve our knowledge of why men and women differ in height and offer a starting point to study genetic reasons for other differences between the sexes. Researchers aim to keep exploring genes like SHOX and how they work with hormones and other body systems to better understand the complicated processes behind human growth and health. First Published: May 27, 2025, 15:28 IST
