Comment

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 6:19am

Smallest species shifting the fastest: Bird body size predicts rate of change in a warming world

Birds across the Americas are getting smaller and longer-winged as the world warms, and the smallest-bodied species are changing the fastest.

That's the main finding of a new study of online publication  in the journal Proceedings of the National Academy of Sciences.

The study combines data from two previously published papers that measured body-size and wing-length changes in a total of more than 86,000 bird specimens over four decades in North and South America. One study examined migrating birds killed after colliding with buildings in Chicago; the other looked at nonmigrating birds netted in the Amazon.

Though the two datasets are nonoverlapping in both species composition and geography, and the data were collected independently using different methods, the birds in both studies displayed similarly widespread declines in body size with concurrent increases in wing length.

Now, a new analysis of the combined data has revealed an even more striking pattern: In both studies, smaller bird species declined proportionately faster in body size and increased proportionately faster in wing length.

Both the Chicago and Amazonian studies attributed the reductions in species body size to increasing temperatures over the past 40 years, suggesting that body size may be an important determinant of species responses to climat4e change.

Even so, exactly why smaller-bodied species are changing faster remains an open question, according to the researchers.

 Zimova, Marketa et al, Body size predicts the rate of contemporary morphological change in birds, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2206971120

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 6:14am

Study finds that experts support DNA sequencing in newborns

New born babies  undergoing routine newborn screening, a laboratory test to identify the risk of up to 60 treatable conditions is beneficial. Because hundreds of genetic disorders, including a growing number of devastating childhood diseases, now have targeted treatments, including gene and cell therapies, that can offer permanent cures. Despite these advances, the addition of genomic sequencing to newborn screening programs has remained controversial.

Findings from a new study led by researchers  suggest that rare disease experts are now in favour of more expansive newborn testing. In a study published recently in JAMA Network Open, 88% of rare disease experts agreed that DNA sequencing to screen for treatable childhood disorders should be made available to all newborns.

The study further identified 432 gene-disease pairs that are not currently screened for, but that were recommended for newborn screening by more than 50% of the experts. Among the genes that most experts recommended for newborn screening were those associated with a lethal liver and brain disorder, the severe bleeding disorders known as hemophilia A and B, and an increased risk for retinoblastoma, a rare and fatal eye tumour in young children.

Early identification of infants who are at risk for genetic disorders can be lifesaving and screening has the potential to improve health care disparities for affected children.

In many cases in which DNA sequencing identifies a child at risk, a blood test or imaging study can then determine whether the disease condition is already underway, enabling early treatment. In other cases, the child will be entirely healthy despite the positive DNA screen and can be followed for the appearance of symptoms and signs in the future. The researchers note that future studies will be needed to determine whether newborn sequencing is cost-effective and positively contributes to short- and long-term outcomes.

Perspectives of Rare Disease Experts on Newborn Genome Sequencing, JAMA Network Open (2023). DOI: 10.1001/jamanetworkopen.2023.12231

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 6:06am

The study finds markers for pathology pre-symptom progression of Parkinson's disease and REM sleep behavior disorder, highlighting the potential role of gut microbiota in the pathogenesis of α-synucleinopathy. The observations open the door for future research to go beyond the correlations and seek the early causative path of both diseases in hopes of discovering what could be a pre-clinical diagnostic intervention to prevent Parkinson's from developing in the first place.

Bei Huang et al, Gut microbiome dysbiosis across early Parkinson's disease, REM sleep behavior disorder and their first-degree relatives, Nature Communications (2023). DOI: 10.1038/s41467-023-38248-4

Part 2

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 6:06am

Early signals of Parkinson's found in gut microbiota of REM sleep behaviour disorder patients

Scientists have found that the gut microbiome holds Parkinson's disease markers and may indicate a method of early diagnosis.

In the study, "Gut microbiome dysbiosis across early Parkinson's disease, REM sleep behavior disorder and their first-degree relatives" published in Nature Communications, the research team looked for correlations in the gut microbiota between comorbid pathologies to see if they could find a causal link.

REM sleep behavior disorder (RBD) causes people to physically act out their dreams while sleeping. RBD affects around 40% of patients with Parkinson's disease (PD), which is also a condition of unintended movements. Patients with RBD are even more likely to acquire PD at some point. The partial overlap in conditions raises interesting questions, and researchers looked to the gut for answers.

In recent years growing knowledge around the gut-brain connection and the relationship between neurological pathologies and microbiota populations has inspired researchers to focus more attention on the role the gut plays in overall human health. While causal relationships are not always clear, correlations between pathologies and microbiota profiles can be strikingly similar across patients with shared diagnoses.

Parkinson's is characterized by the abnormal aggregation of a presynaptic neuronal protein in the central nervous system (spine and brain), alpha-synuclein (α-syn). While this had been considered causal to the pathology, the authors cite studies offering increasing evidence that α-syn pathology has already occurred in the enteric nervous system (neurons embedded into the walls of the gastrointestinal system).

Following the related symptom progression backward, RBD is considered the most specific precursor signal of Parkinson's. Patients with RBD report having an increased prevalence of constipation and increased phosphorylated α-syn immunostaining in their enteric nervous system. Parkinson's patients with RBD features also exhibit these increased constipation and enteric α-syn histopathology effects compared to those without RBD, suggesting a distinct subtype of Parkinson's disease that reflects a gut-brain link of α-synucleinopathy.

The researchers performed a cross-sectional microbiome study across prediagnoses and early stages of the diseases along with controls and RBD relative to disentangle the associations of gut microbiota with the progression of α-synucleinopathy.

The study found gut microbiota compositions significantly altered in early PD and RBD compared with controls and the relative cohort. In RBD patients, the overall microbiota composition shifted closer to those with early Parkinson's.

Random forest modeling identified 12 microbial markers, including depletion of butyrate-producing bacteria and an overabundance of Collinsella, Desulfovibrio, and Oscillospiraceae UCG-005. The profile produced a signal distinct enough to distinguish RBD from controls reliably with machine learning assistance. These findings suggest that Parkinson's-like microbiota profile changes occur at the early stages of RBD-related Parkinson's when RBD first develops.

Another interesting find was the depletion of butyrate-producing bacteria and enrichment of pro-inflammatory Collinsella in RBD relatives, a group that had not yet shared any of the other tell-tale signatures in the microbiota, hinting at a pre-precursor signal that needs further investigation.

Part 1

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 5:58am

The findings gathered by this team of researchers offer some interesting new insight about what past experiences humans tend to replay in their brain before deciding whether to approach or avoid a certain situation.

Jessica McFadyen et al, Differential replay of reward and punishment paths predicts approach and avoidance, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01287-7

Part 2

Comment by Dr. Krishna Kumari Challa on May 9, 2023 at 5:58am

Replaying outcomes in the brain could predict whether we approach or avoid situations

Past neuroscience studies suggest that when deciding their next actions, mice and other rodents tend to replay past outcomes of similar situations in their brain, which is reflected in a rapid activation of certain brain regions in a sequence. Recently, some studies recorded similar replay-associated brain activity in the human brain using imaging techniques.

Researchers  have carried out a study exploring the possibility that this rapid "replay" of past positive and negative outcomes could predict the choices that humans make in a situation where they could either lose or gain money. Their findings, published in Nature Neuroscience, unveil a possible link between replay in the brain and the planned behaviour of humans, suggesting that while choosing to approach or avoid a situation, humans mentally represent the worst case scenario that could result from their choice.

Researchers wanted to examine how different paths are replayed in the human brain in situations where the outcome is not easy to deduce. Specifically, they examined scenarios in which humans might be conflicted about whether to approach or avoid a given path, a dilemma known as the approach-avoidance conflict.

Choosing whether to stay (avoid) or go (approach) is hard when we're uncertain, and it's possible that replay in the brain could explain how we eventually make up our mind. To test this hypothesis, researchers used a brain imaging technique called magnetoencephalography, which entails the use of a machine that sits on the scalp to pick up the tiny electric currents that pass through human neurons.

Magnetoencephalography allows researchers to precisely measure bursts of activity in different areas of the brain and when they occur. They specifically used it to measure the very fast bursts of brain activity that happen in the brain during replay, which are only about 40 milliseconds apart.

After they collected their brain recordings, the researchers used machine learning to analyze them and determine which of the images they were previously presented with were replayed in the brain while participants made a new decision. In other words, the models they used detected the re-activation of sequences of brain activity that were first recorded while the participants were initially presented with a given image.

By analyzing these results in combination with the decisions that participants took (i.e., whether they approached or avoided a given situation), researchers were then able to determine what sequences were being replayed before participants decided to approach or avoid a given path.

Their biggest finding was that humans play out paths of the worst-case scenario. If participants eventually decided to avoid altogether, they tended to replay (or rather 'simulate') paths leading to the desired but forgone reward. On the other hand, if participants eventually decided to approach and take the risk, they tended to replay paths leading to the feared negative outcome. This sort of counterfactual thinking could be a way for the brain to make sure we don't forget alternative outcomes.

Part 1

Comment by Dr. Krishna Kumari Challa on May 8, 2023 at 11:47am

For their most recent study, the team compared the genomes of 241 mammal species using machine learning to cope with a large amount of data.

They identified 312 HARs and examined where they are located within the 3D 'neighborhoods' of folded DNA. Almost 30 percent of HARs were in the regions of DNA where structural variations had caused the genome to fold differently in humans compared to other primates.

The team also discovered neighborhoods containing HARs were rich with the genes that differentiate humans from our closest relatives, chimpanzees.

In an experiment that compared DNA within growing human and chimpanzee stem cells, one-third of identified HARs were transcribed specifically during the development of the human neocortex.

Many HARs play a role in embryo development, especially in forming neural pathways associated with intelligence, reading, social skills, memory, attention and focus – traits we know are distinctly different in humans than other animals.

In HARs, these enhancer genes, unchanged for millions of years, may have had to adapt to their different target genes and regulatory domains.

Something big happens like this massive change in genome folding, and our cells have to quickly fix it to avoid an evolutionary disadvantage."

We don't yet understand exactly how these changes have impacted specific aspects of our brain development, and how they became an integral part of our species' DNA. 

https://www.science.org/doi/10.1126/science.abm1696

Part 2

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Comment by Dr. Krishna Kumari Challa on May 8, 2023 at 11:45am

A Chance Event 1 Million Years Ago Changed Human Brains Forever

Like treasured recipes passed down from generation to generation, there are just some regions of DNA that evolution doesn't dare tweak. Mammals far and wide share a variety of such encoded sequences, for example, which have remained untouched for millions of years.

Humans are a strange exception to this club. For some reason, recipes long preserved by our ancient ancestors were suddenly 'spiced up' within a short evolutionary period of time.

Because we're the only species in which these regions have been rewritten so rapidly, they are called 'human accelerated regions' (or HARs). What's more, scientists think at least some HARs could be behind many of the qualities that set humans apart from their close relatives, like chimpanzees and bonobos.

In a new study, researchers found the 3D folding of human DNA in the nucleus is a key factor in this pivotal moment for our species.

A big difference between human and chimpanzee DNA is structural: large chunks of the DNA's building blocks have been inserted, deleted, or rearranged in the human genome. So human DNA folds differently in the nucleus compared with the DNA of other primates.

In a study published earlier this year, researchers created a model suggesting the rapid variations appearing in HARs in early humans often opposed each other, turning the activity of an enhancer up and down in a kind of genetic fine-tuning – a model supported by their new research.

Part 1

Comment by Dr. Krishna Kumari Challa on May 8, 2023 at 11:17am

Strange planets

Comment by Dr. Krishna Kumari Challa on May 8, 2023 at 11:09am

Happy worms have healthy eggs

 Worms might not be depressed, per se. But that doesn’t mean they can’t benefit from antidepressants.

In a new study researchers exposed roundworms (a well-established model organism in biological research) to selective serotonin reuptake inhibitors (SSRIs), a class of drugs used for treating depression and anxiety. Surprisingly, this treatment improved the quality of aging females’ egg cells.

Not only did exposure to SSRIs decrease embryonic death by more than twofold, it also decreased chromosomal abnormalities in surviving offspring by more than twofold. Under the microscope, egg cells also looked younger and healthier, appearing round and plump rather than tiny and misshapen, which is common with aging.

Astounded by the results, the researchers replicated the experiment in fruit flies — another common model organism — and the SSRIs demonstrated the same effect.

Although much more work is needed, the researchers say these findings provide new opportunities to explore pharmacological interventions that might combat infertility issues in humans by improving egg quality and by delaying the onset of reproductive aging.

Erin Z. Aprison, Svetlana Dzitoyeva, Ilya Ruvinsky. Serotonergic signaling plays a deeply conserved role in improving oocyte quality. Developmental Biology, 2023; DOI: 10.1016/j.ydbio.2023.04.008

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