Monday, November 27, 2023

 

Why does puberty trigger us to stop growing?


Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS CHICAGO




All animals start out as a single-celled organism and then start growing. At some point, of course, they need to stop getting bigger, but the process by which this happens is poorly understood. 

New research from Alexander Shingleton at the University of Illinois Chicago and colleagues identifies a potential trigger that makes fruit flies stop growing, which has implications for understanding human development. The research is published in the Proceedings of the National Academy of Sciences

In humans, the body’s signal to stop growing happens around puberty, though it takes several more years before growth actually ceases. It is important to better understand this process in part because of recent changes in how children experience puberty. 

“We know that the onset of puberty is getting younger and younger. But in order to understand why something is changing, you need to understand how it works,” said Shingleton, a professor of biological sciences.  

So the researchers looked at fruit flies, which undergo the equivalent of puberty when they metamorphosize from larvae into adults. The theory among many biologists has been that a larva stops growing when it reaches a certain body size, which triggers it to start the process of becoming an adult. Other insects do this, such as the kissing bug, which uses a “stretch receptor” in its abdomen to monitor its size, Shingleton explained.  

But Shingleton and his coauthors weren’t convinced that fruit flies were using such a mechanism. They hypothesized that it had something to do with a steroid hormone involved in fruit fly growth called ecdysone, which is similar to estrogen and testosterone in humans.  

The researchers used a mathematical model to explore their idea. The model showed that body size is not the trigger that causes a fruit fly to stop growing. Instead, a “stop growing” switch is triggered by the gland that makes ecdysone. In the larval stage, that gland receives lots of nutritional information that helps it decide how to regulate ecdysone production. But once ecdysone reaches a certain level, the gland no longer needs that nutritional information to make decisions and starts regulating itself. 

The researchers believe this switch from needing nutritional information is what triggers the fruit fly to stop growing. “It’s not that the fly is measuring itself in a direct way,” Shingleton said.  

He’d like to see similar studies done on mammals, which could shed more light on the growth-stopping process in humans. But Shingleton suspects that the fruit fly experience is related to ours, given that both involve similar steroid hormones and both fruit flies and humans convey nutritional information via insulin. 

The other researchers on the project are UIC undergraduate student Amirali Monshizadeh, John Tyson at Virginia Tech and Stanislav Shvartsman at Princeton.

Written by Emily Stone 

 

Not only is virtual care safe, patients and providers use it effectively, new research finds


Peer-Reviewed Publication

MCMASTER UNIVERSITY




New research from McMaster University has found that not only is virtual care a safe way to hold medical appointments, but that patients and physicians were able to use it appropriately and effectively with minimal guidance.

The study, published in Healthcare Quarterly on Nov. 27, was led by Shawn Mondoux, an emergency physician and associate professor in the Department of Medicine at McMaster. Mondoux and his team wanted to find out just how safe virtual care is when compared to an in-person assessment.

To do this, researchers keyed in specifically on virtual care in Ontario and utilized data from ICES. This included data from the Ontario Health Insurance Plan (OHIP) database. Virtual care has seen a meteoric rise in use since the beginning of the pandemic and can include video and phone appointments.

Then, to ensure an appropriate comparison, they grouped patients based on several conditions, like age, gender, similar historical illnesses, and their history of diagnosis. This resulted in more than 18 million visits being included in the analysis, split evenly between virtual and in-person care. Researchers then looked at patient outcomes at seven and 30 days following their appointment.

“So the result was that when you look at the two populations together, those who were seen in virtual care had less bad outcomes, had less hospitalization, and less visits to intensive care units, and really had less health care visits, with the exception of one place, which was they tended to see their own family doctors virtually more often than patients seen in-person,” Mondoux says.

It’s important to note that the researchers couldn’t account for the acuity of the patients between the groups in this study.

“So, if you're super sick, you as a patient may in fact choose to say, ‘I'm really sick. This isn't a virtual call thing. I'm going into the emergency department, or I'm going to go see my doctor, or I'm going to go see my specialist.’ And very reasonably, your family physician may also say the same thing. That acuity or that level of sickness isn't something we could totally match for.”

Mondoux says that virtual care is not only safe, but that patients and physicians are making good choices about the use of it.

“The in-person care system is probably taking care of much sicker patients, which is exactly what it should be doing. We released a technology that was brand new. And somehow, everybody just knew how to use it really well.”

Mondoux hopes the research can spur a conversation amongst policymakers about the use of virtual care, by turning the topic away from it being about whether it’s effective, and instead focus on who it is best suited for.

“This can save patients travel to a hospital, parking, and commute time. And there's a lot of patients out there who don't have access to their own vehicle or family members to do all this stuff. So, this is  a helpful modality,” he says.

This study received funding from the Juravinski Research Institute and the Graham Farquharson Knowledge Translation Fellowship.

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To arrange an interview with lead author Shawn Mondoux, you can email him directly at mondous@mcmaster.ca.

 

Honeybee cluster—not insulation but stressful heat sink


Peer-Reviewed Publication

UNIVERSITY OF LEEDS

Tree nest and hive together 

IMAGE: 

TREE NEST AND HIVE TOGETHER

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CREDIT: D. MITCHELL




With images - the visual assets can be downloaded by clicking on this WeTransfer link:https://we.tl/t-mbRtSW5BzO

*See further information at end of release for captions and required pic credits 

A Leeds researcher is keen to help beekeepers shape their practices following his study which appears to disprove the widespread belief that honeybees naturally insulate their colonies against the cold. His findings suggest that the creatures are potentially being subjected to thermally-induced stress.

University of Leeds PhD student Derek Mitchell is calling for further debate on the ethical treatment of insects, saying his research appears to contradict the widely-accepted theory that the bees’ reaction to cold temperatures is to form layers of insulation – an idea that has led to them being housed in hives that are extremely poorly insulated compared to their natural habitat.

The study, which is published in the Journal of the Royal Society Interface, looks at honeybee “clusters” - where the insects huddle together, forming dense disks between the combs, to try to keep some of them above 18°C when the outside temperature drops. For almost 120 years, the outer layer of honeybees in the winter cluster – known as the mantle - has been said to insulate the cluster core – the honeybees at the centre.

Adopting the same techniques used for measuring heat loss from buildings, Mr Mitchell - from the School of Mechanical Engineering - analysed this theory. However, his findings indicate that far from acting as insulation, the mantle instead acts like a heat sink – dissipating the heat away from the centre. The paper states: “The cluster mantle does not meet any the four insulation criteria identified and meets all three heat sink criteria.” 

Mr Mitchell said: “My findings are controversial because it has become a tenet of beekeeping - that the mantle insulates the honeybees.” 

He explains that once the outside temperature falls, the heat needed to sustain 18°C+ inside goes up. If the bees cannot produce that much heat, the temperature near the hive wall drops and the honeybees near it become chilled and they move closer to bees that can still efficiently produce heat. They get closer together and their combined thermal conductivity increases, which further increases the heat loss.

He said: “This new research indicates that, rather than being benign, clustering is a survival behaviour in response to an existential threat - resulting in increased stress due to cold and exertion. Some honeybees may even eat their own young to survive.”

He added: “In anthropomorphic terms, clustering is not a “wrapping of a thick blanket” to keep warm - but more like a desperate struggle to crowd closer to the “fire” or otherwise die.”

He said: “I want to share my research, to raise awareness of the welfare issues and to help educate beekeepers about the complex interaction of the colony enclosure and thermofluids - heat, radiation, water vapour, air - with honeybee behaviour and physiology.”

Harvey M. Thompson, Professor of Computational Fluid Dynamics at the University of Leeds, who supervised the new research, said: “It’s great to see how mechanical engineering can be applied to such a variety of fields and how these findings can potentially be used to help beekeepers in the future.”

Mr Mitchell’s research came about when his wife took up beekeeping and he noticed that people still used hives designed in the 1930s and 1940s.

He said: “The hives beekeepers used were at odds with what I knew about heat transfer and what beekeepers had told me about honeybees. I thought I could build better hives, so started out trying to find the requirements of the honeybees and found out that nobody knew in terms that made engineering sense.”

After studying mechanical engineering as a student apprentice, he returned to the subject as a PhD student. Using engineering techniques more commonly used to solve industrial problems, his previous research suggested that most manufactured hives have seven times more heat loss than natural nests.

Mr Mitchell, who also has a Physics BSc, Microelectronics MSc and worked in spacecraft ground control software, said he believed misconceptions around clustering had, in part, arisen because the creatures’ overwintering behaviour was dominated by observations in thin (19mm) wooden hives, with very different thermal properties to their natural habitat of thick walled (150mm) tree hollows.

He said those long-held beliefs have encouraged enforced clustering, by beekeepers’ dominant use of what he labels “inadequately insulated hives” and, in North America, refrigeration. This is often seen as a benign or even a necessary process, with beekeeping and academic research considering these conditions of extreme heat loss as natural and normal. 

He is calling for changes in practice to be urgently considered, researched and promoted, as well as further debate on the ethical treatment of honeybees and insects. 

Research paper: Honeybee cluster—not insulation but stressful heat sink is being published in the Journal of the Royal Society Interface at 00.01 GMT on November 22, 2023. When the embargo lifts, the paper will be available on the journal website: https://doi.org/10.1098/rsif.2023.0488

ENDS

 

Collaboration between women helps close the gender gap in ice core science


Analyzing the evolution of women's participation in ice core research


Peer-Reviewed Publication

UNIVERSITY OF ALBERTA




A Perspective article published today in Nature Geoscience tackles the longstanding issue of gender representation in science, focusing on the field of ice core science. Prior work has shown that despite progress toward gender parity over the past fifty years1, women continue to be significantly underrepresented within the discipline of Earth sciences2 and receive disproportionately fewer opportunities for recognition, such as invited talks, awards, and nominations3. This lack of opportunity can have long-term negative impacts on women’s careers. To help address these persistent gender gaps, the study evaluates patterns related to women’s publication in ice core science over the past fifty years. The study was co-led by Bess Koffman of Colby College, USA, and Matthew Osman of Cambridge University, UK, and coauthored by Alison Criscitiello and Sofia Guest, both of the University of Alberta, Canada.

To assess relationships among gender, publication rate, and impact of coauthor networks, the study evaluates a comprehensive, global dataset of abstracts representing published work in ice core science spanning 1969 to 2021 in this historically male-dominated discipline. The Perspective article shows that the inferred gender gap in ice core science has declined from roughly 10:90% women:men in the 1970’s to ~30:70% in the past decade. Contrasting with prior work across the sciences, the authors find that women’s and men’s coauthor networks have remained similarly sized and been similarly cited through time. This finding may reflect the high degree of international cooperation and the large collaborative teams that are typical of the field of ice core science.

Importantly, the gender makeup of coauthors differs substantially for man vs. woman-led studies. Strikingly, within the past decade, woman-led studies have contained on average 20% more women coauthors than man-led studies, a difference found to be even greater in earlier decades. Moreover, since the early 2000s, the analysis shows that women have out-performed by about 8% their estimated proportion within the ice core community in terms of publishing first-authored papers. The new analysis by Koffman, Osman, Criscitiello and Guest suggests that senior women in particular catalyze women’s participation in publishing, and that collaboration between women can help close gender gaps in science.

References cited:

1 Bernard, R. E. & Cooperdock, E. H. G. No progress on diversity in 40 years. Nature Geoscience 11, 292-295, doi:10.1038/s41561-018-0116-6 (2018).

2 Holmes, M. A., O'Connell, S., Frey, C. & Ongley, L. Gender imbalance in US geoscience academia. Nature Geoscience 1, 79-82 (2008).

3 Ford, H. L., Brick, C., Blaufuss, K. & Dekens, P. S. Gender inequity in speaking opportunities at the American Geophysical Union Fall Meeting. Nature Communications 9, doi:10.1038/s41467-018-03809-5 (2018).

4 Pico, T., Bierman, P., Doyle, K. & Richardson, S. First Authorship Gender Gap in the Geosciences. Earth and Space Science 7, doi:10.1029/2020EA001203 (2020).

 

Stanford Medicine study reveals why we value things more when they cost us more


Neural basis for “sunk cost” pride


Peer-Reviewed Publication

STANFORD MEDICINE




Ahab hunting down Moby Dick. Wile E. Coyote chasing the Road Runner. Learning Latin. Walking over hot coals. Standing in a long line for boba tea or entrance to a small, overpriced clothing retail store. Forking up for luxury nonsense.

What do these activities have in common? They’re all examples of the overvaluation of what economists call “sunk costs”: the price you’ve already irretrievably paid in time, money, effort, suffering or any combination of them for an item, an experience or a sense of self-esteem.  

It’s a phenomenon we all recognize. It affects our behavior in ways that can be irrational. But we do it.

Here’s my story: My glacial-blue ’64 stick-shift Volvo station wagon had red, white and blue Colorado U.S. Bicentennial plates and a phalanx of three small bowling trophies for hood ornaments (I called it “the Bowlvo”). It was falling apart like a piece of overcooked chicken. (One day, I was shooting down Highway 25 in Colorado when the hood flew up in my face. Another time, as I was frantically downshifting into second gear while driving home at my usual unsafe speed on a winding mountain road, the shift lever came off in my hand.) I would have gone to the ends of the earth, or at least the end of my rope, to keep it in running condition. Or failing that, just to keep it.

For mysterious reasons, we are hardwired to value something more if we’ve put a lot of sweat equity — what we had to do to get (or in my case keep) that reward — into it. Neuroscientists are trying to figure out why we do that.

Shared stupidity

“We make fallacious decisions based on what we’ve invested in something, even if the probability of actually gaining an objective advantage from it is zero,” said assistant professor of psychiatry and behavioral science Neir Eshel, MD, PhD. “And it’s not just us. This has been shown in animals across the animal kingdom.”

OK — all higher animals are hardwired to make dumb decisions. But why?

Blame dopamine: the “do it again, do it some more” brain chemical that’s been much talked about in connection with pleasure, learning and habit formation.

There’s a difference between wanting something and liking it, said Eshel, who focuses on how the brain motivates behavior. “You can want something very, very much even though you don’t even like it very much. Or vice versa.”

A few years ago, Eshel, his then-postdoctoral adviser Rob Malenka, MD, PhD, the Nancy Friend Pritzker Professor in Psychiatry and the Behavioral Sciences, and some Stanford Medicine colleagues began conducting experiments to learn more about wanting versus liking and what, if any, role dopamine secretion in the brain plays in each of these states.

“We looked at how much an animal likes something — how much it will consume if that something is cost-free — and how much it wants something — how much that animal’s consumption is affected by the cost of getting it,” Eshel said.

The results of that experimentation are in a paper to be published Nov. 27 in Neuron.

The dopamine connection

In the course of their study, they came up with a possible neural mechanism for the longstanding psychological observation that we value rewards more if we worked harder for them: Dopamine release in the striatum, it turns out, is greatly influenced by the effort put forth to gain a reward.

“Now we may have found the neural basis for sunk cost,” Eshel said. “Dopamine could explain it.”

In their study of mice, the researchers defined “cost” as either the number of times the mice had to poke their noses into a hole in a box (anywhere between just once and nearly 50 times) or risk incurring mild to moderate foot shocks to get access to a “reward”: either sugar water or instant direct stimulation of dopamine release in two centers in a structure in the middle of the brain called the striatum. These centers are well known for their role in motivation and movement (motion), their abundance of dopamine receptors, and their innervation by dopamine-secreting tracts originating in regions deeper in the brain. And for their involvement in learning, habit formation and addiction.

The researchers first determined the test animals’ “cost-free consumption”: how much a mouse will consume until satiation in a cost-free situation (all it had to do was stick its nose in the hole, and bingo!). That told the investigators how much the mouse “liked” something.

Then, in steps, they raised the cost of acquisition by increasing the number of nose-pokes, or the intensity of electric shocks to a mouse’s feet, required to get the reward.

The researchers likewise methodically varied the amounts of reward (whether sucrose or direct stimulation of dopamine release in the striatum) animals got for a given amount of persistence or discomfort.

Dopamine release in mice’s striatum was assessed as soon as each reward was earned.

Not too surprisingly, striatal dopamine release was influenced by the size of the prize. But, the scientific team learned, raising the reward’s cost also triggered greater dopamine release in the striatum: There was a biochemical basis for the concept of sunk cost.

Sunk cost and survival

How does this make any evolutionary sense? To an economist, valuing something because of sunk costs is aberrant decision making.

One idea, Eshel suggested: “In an environment with limited resources (as most are), when we typically get rewarded only after really hard work, we may need high dopamine secretion to get us to do it again.”

“Because dopamine reinforces previous behaviors, it may reflect sunk costs,” he said. “The dopamine release we saw may enable you to pay those steep costs in the future.”

Maybe Eshel could have tested me instead. I know a thing or two about sunk costs.

I still miss the Bowlvo.              

The research was funded by the National Institutes of Health (grants K08MH123791 and P50DA04201), the Brain & Behavior Research Foundation, the Burroughs Wellcome Fund, the Simons Foundation, and the Stanford Wu Tsai Neurosciences Institute.

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About Stanford Medicine

Stanford Medicine is an integrated academic health system comprising the Stanford School of Medicine and adult and pediatric health care delivery systems. Together, they harness the full potential of biomedicine through collaborative research, education and clinical care for patients. For more information, please visit med.stanford.edu.

 

Deoxygenation levels similar to today’s played a major role in marine extinctions during major past climate change event


Peer-Reviewed Publication

TRINITY COLLEGE DUBLIN

Carnduff cores 

IMAGE: 

SAMPLING OF THE CARNDUFF CORES (HERE STUDIED), WHICH WERE DRILLED IN THE LARNE BASIN, NORTHERN IRELAND.

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CREDIT: PROF. MICHA RUHL, TRINITY COLLEGE DUBLIN





Scientists have made a surprising discovery that sheds new light on the role that oceanic deoxygenation (anoxia) played in one of the most devastating extinction events in Earth’s history. Their finding has implications for current day ecosystems – and serves as a warning that marine environments are likely more fragile than apparent.

New research, published today in leading international journal Nature Geosciences, suggests that oceanic anoxia played an important role in ecosystem disruption and extinctions in marine environments during the Triassic–Jurassic mass extinction, a major extinction event that occurred around 200 million years ago. 

Surprisingly however, the study shows that the global extent of euxinia (an extreme form of de-oxygenated conditions) was similar to the present day.

Earth’s history has been marked by a handful of major mass extinctions, during which global ecosystems collapsed and species went extinct. All past extinction events appear to have coincided with global climatic and environmental perturbance that commonly led to ocean deoxygenation. Because of this, oceanic anoxia has been proposed as a likely cause of marine extinctions at those times, with the assumption that the more widespread occurrence of deoxygenation would have led to a larger extinction event.

Using chemical data from ancient mudstone deposits obtained from drill-cores in Northern Ireland and Germany, an international research team led by scientists from Royal Holloway (UK), and including scientists from Trinity College Dublin’s School of Natural Sciences (Ireland) as well as from Utrecht University (Netherlands), was able to link two key aspects associated with the Triassic–Jurassic mass extinction.

The team discovered that pulses in deoxygenation in shallow marine environments along the margins of the European continent at that time directly coincided with increased extinction levels in those places.

On further investigation – and more importantly – the team also found that the global extent of extreme deoxygenation was rather limited, and similar to the present day. 

Micha Ruhl, Assistant Professor in Trinity’s School of Natural Sciences, and research-team member, said: 

“Scientists have long suspected that ocean deoxygenation plays an important role in the disturbance of marine ecosystems, which can lead to the extinction of species in marine environments. The study of past time intervals of extreme environmental change indeed shows this to be the case, which teaches us important lessons about potential tipping points in local, as well as global ecosystems in response to climatic forcing.

“Crucially however, the current findings show that even when the global extent of deoxygenation is similar to the present day, the local development of anoxic conditions and subsequent locally increased extinction rates can cascade in widespread or global ecosystem collapse and extinctions, even in areas where deoxygenation did not occur. 

“It shows that global marine ecosystems become vulnerable, even when only local environments along the edges of the continents are disturbed. Understanding such processes is of paramount importance for assessing present day ecosystem stability, and associated food supply, especially in a world where marine deoxygenation is projected to significantly increase in response to global warming and increased nutrient run-off from continents.”

The study of past global change events, such as at the transition between the Triassic and Jurassic periods, allows scientists to disentangle the consequences of global climatic and environmental change and constrain fundamental Earth system processes that control tipping points in Earth’s ecosystems.

 

A core sample of ~201 million year old sediments obtained from the Carnduff-2 core, drilled in the Larne Basin (Northern Ireland), showing the shell of an animal that lived on the seabed shortly after the Triassic–Jurassic global mass extinction.

CREDIT

Prof. Micha Ruhl, Trinity College Dublin

Professor Micha Ruhl in the lab.

JOURNAL

 

Wind and solar projects can profit from bitcoin mining


Peer-Reviewed Publication

CORNELL UNIVERSITY




ITHACA, N.Y. – Bitcoin mining is often perceived as environmentally damaging because it uses huge amounts of electricity to power its intensive computing needs, but a new study demonstrates how wind and solar projects can profit from bitcoin mining during the precommercial development phase — when a wind or solar farm is generating electricity, but has not yet been integrated into the grid.

The findings suggest some developers could recoup millions of dollars to potentially invest in future renewable energy projects.

The study, “From Mining to Mitigation: How Bitcoin Can Support Renewable Energy Development and Climate Action,” was published in the journal ACS Sustainable Chemistry & Engineering and is authored by Cornell University doctoral student Apoorv Lal and Fengqi You, professor in energy systems engineering at Cornell. Jesse Zhu, professor from the Western University of Canada, also contributed to the research.

Texas emerged from the analysis as the state with the most potential, with 32 planned renewable projects that could generate combined profits of $47 million using bitcoin mining during precommercial operations. Projects in California produced the second highest profits in the study, while Colorado, Illinois, Iowa, Nevada and Virginia had fewer installations but still show profitability.

“Profitability of a mining system hinges on periods of steady energy availability since renewable energy sources can vary significantly,” said You. “Therefore, it is important to site the mining farm strategically to maximize productivity.”

As an example, You pointed to California, Colorado, Nevada and Virginia as states where solar installations were the only type of renewable energy project that proved profitable in generating bitcoin during the precommercial phase.

The researchers suggest several policy recommendations that could help improve the economic feasibility of renewable energy projects and reduce carbon emissions. One is to provide economic rewards for environmentally responsible cryptocurrency mining, such as carbon credits for avoided emissions.

“These rewards can act as an incentive for miners to adopt clean energy sources, which can lead to combined positive effects on climate change mitigation, improved renewable power capacity, and additional profits during precommercial operation of wind or solar farms,” Lal said. “We also recommend policies that encourage cryptocurrency-mining operations to return some of their profits back into infrastructure development. This would help create a self-sustaining cycle for renewable energy expansion.”

While the study’s authors acknowledge other aspects of cryptocurrency mining still have environmental costs, for example, metal depletion and hardware that becomes obsolete within a few years, they said the results indicate that there are ways to mitigate some of the environmental costs of cryptocurrency mining and foster investments in renewable energy.

The research was partially funded by the National Science Foundation.

For additional information, see this Cornell Chronicle story.

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