Wednesday, July 24, 2024

Evolutionary history and biological adaptation of Han Chinese people on the Mongolian Plateau

TSINGHUA UNIVERSITY PRESS

Comprehensive characterization of the effect of the complex demographic processes and natural selection pressures on the patterns of human genetic diversity is essential for understanding the human history of ethnolinguistically different populations and the evolutionary trajectory of the molecular genetic basis of adaptive traits and complex diseases. "Large-scale population-specific ancient and modern genomic resources provide a direct spatiotemporal research window for elucidating the origin, migration, admixture, biological adaptation, and the geographical origins and diffusion trajectories of the genetic architecture of human diseases," says Chao Liu, an Academician at the Chinese Academy of Engineering and co-corresponding author from the Anti-Drug Technology Center of Guangdong Province.

Recent population genetic studies on the specific ancestry of ancient and modern genomes in Western Eurasian populations have revealed the differential genetic contributions of late Upper Paleolithic European hunter-gatherers, Neolithic Anatolian agriculturalists, and Bronze Age Eurasian steppe pastoralists to the genetic basis of the complex traits such as waist-to-hip ratio and height in modern Europeans. Path-specific local ancestry analyses of ancient and modern genomes in Europe have shown that the spread of Western steppe populations 5,000 years ago shaped the genetic susceptibility to multiple sclerosis in modern European populations, with higher prevalence in the north and lower in the south. However, there is a relative scarcity of research based on ancient and modern genomic databases to dissect the geographical origins and evolutionary trajectories of diseases or biological adaptive traits in East Eurasians.

“To address this gap in eastern Eurasian populations and provide deeper insights into the evolutionary history of ancestrally different eastern Eurasian and the evolutionary origin of the population-specific genetic basis of complex biological traits, we explored ancestral composition and characterized the evolutionary trajectory of the adaptive traits in Han Chinese populations using an integrated modern and ancient genomic database,” says Guanglin He, corresponding author from Sichuan University.

Population history

The Han is the largest ethnic group globally, distributed across China in diverse ecological environments and dietary patterns. The Mongolian Plateau in northern East Asia is home to both Sinitic-speaking Han and Altaic-speaking populations. Historical records document various regimes in the region, including the Xiongnu (209 BCE–98 CE), Xianbei (386–534 CE), Türkic (552–742 CE), Uyghur (744–840 CE), and Khitan (916–1125 CE). Archaeological and genetic evidence suggests an extensive cultural and genetic interaction between the Han and these minority ethnic groups.

Mengge Wang, the co-first author from Sichuan University, states, “Population-specific genomic resource is important for reconstruction of population history and improves human health equality in the precision medicine is. Additionally, the population interaction on the Mongolian Plateau is very interesting, and we have done early research on the genetic origin and population history of Mongolian people. In this project, we mainly carried out population genetics focused on the population history and biological adaptation for the Han Chinese population on the Mongolian plateau, and found many interesting stories related to the evolution of key adaptative mutations.” Scientists comprehensively characterized the demographic history and biological adaptation of Han Chinese individuals on the Mongolian Plateau using the allele frequency spectrum and haplotype-resolved fragments.

The study revealed a pronounced genetic homogeneity among Han populations across various regions of the Mongolian Plateau. Compared to their counterparts from the Central Plains, the Han inhabitants of the Mongolian Plateau exhibit greater genetic drift with Altaic-speaking populations. Advanced admixture modeling confirmed that the gene pool of the Han population on the Mongolian Plateau has been influenced by gene flow from populations related to Altaic-speaking groups.

Biological adaptation

The study identified natural selection signals linked to the cold environment of the Mongolian Plateau, shifts in subsistence strategy, and immunity changes under pathogen exposures through various computational modeling and detection methods. "We performed multiple complementary statistical analyses, including allele frequency-based population branch statistics (PBS), pairwise fixation index (FST) estimates, haplotype-based cross-population extended haplotype homozygosity (XP-EHH), and the integrated haplotype score (iHS), to detect natural selection signals in the Han population of the Mongolian Plateau. The most significant were candidate genes related to metabolism, FADS, and MTHFR," says Xiangping Li from Kunming Medical University, the study's first author.

The FADS gene family encodes fatty acid desaturase enzymes, which regulate the synthesis of polyunsaturated fatty acids. The MTHFR gene encodes methylenetetrahydrofolate reductase, essential in the folate cycle. Researchers used genomic resources with high spatiotemporal resolution from both ancient and modern samples to reconstruct the evolutionary trajectories of the most salient natural selection signals, [rs174550 (FADS1) and rs1801133 (MTHFR)], over tens of thousands of years.

The findings suggest that the frequency of the advantageous allele rs174550-T increased steadily after its emergence, stabilizing around 0.54. Similarly, the allele rs1801133-A, which appeared in millet agricultural populations around ten thousand years ago, reached high frequencies in regions near 40 degrees north latitude due to dietary shifts associated with agriculture. In Chinese populations, the frequency of rs1801133-A declines continuously from north to south.

The development of cereal agriculture in the Near East's Fertile Crescent and millet farming in the Yellow River basin of East Asia accelerated the adaptation and stabilization of genetic diversity patterns linked to metabolic genes. Phenotypic association analysis of adaptive signals revealed polygenic adaptation and pleiotropy patterns in complex traits within the Han population of the Mongolian Plateau.

The advent of wheat and barley agriculture in the Near East and millet farming in the Yellow River basin spurred rapid adaptation and stabilization of genetic diversity in metabolic genes. Phenotypic association analyses of bio-adaptive signals revealed polygenic adaptation and pleiotropic patterns in complex traits within the Han population of the Mongolian Plateau.

“Our study enhances the understanding of how complex population genetic backgrounds and demographic events influence the genetic determinants of the disease and phenotypes, potentially advancing personalized precision medicine,” says Liping Hu of Kunming Medical University.

M.W. is supported by the National Natural Science Foundation of China (82202078). G.H. is supported by the Major Project of the National Social Science Foundation of China (23&ZD203), the Open Project of the Key Laboratory of Forensic Genetics of the Ministry of Public Security (2022FGKFKT05), the Center for Archaeological Science of Sichuan University (23SASA01), the 1.3.5 Project for Disciplines of Excellence, West China Hospital, Sichuan University (ZYJC20002), and the Sichuan Science and Technology Program. L.H. is supported by the Open Project of Shanghai Key Laboratory of Forensic Medicine (KF202309).

See the article:

Li X, Wang M, Su H, et al. Evolutionary history and biological adaptation of Han Chinese people on the Mongolian Plateau. hLife 2024;2:296–313.

https://doi.org/10.1016/j.hlife.2024.04.005

JOURNAL

hLife

DOI

10.1016/j.hlife.2024.04.005

ARTICLE TITLE

Evolutionary history and biological adaptation of Han Chinese people on the Mongolian Plateau

Egg freezing: Britain’s largest ever study reports live birth outcomes comparable to those of routine IVF

Findings from a London clinic-based study add to a pattern of consistent, predictable and reliable success.

Peer-Reviewed Publication

REPRODUCTIVE BIOMEDICINE ONLINE

18 July 2024:

Britain’s largest ever study of egg freezing which followed up the outcome of almost 30,000 eggs frozen at the London Women’s Clinic shows that success rates are comparable to those achieved by routine IVF and subject to the same variables of female age and embryo quality.(1) When seen alongside other similar large-scale egg-freezing studies from other countries, the results of this study add to a pattern of success which is consistent, predictable and reliable.

The study, published today in the peer-reviewed journal Reproductive Biomedicine Online, analysed the outcomes of treatment for 299 patients who had frozen their eggs between 2008 and 2022 and returned to thaw them for fertilisation and pregnancy. The results of this 15-year study found an overall live birth rate per embryo transfer of 26% which varied according to the age at which the eggs were frozen, with a lower rate in over-35s but only 5% in over-40s.

The cumulative live birth rate after the transfer of all embryos created from the thawed eggs was 34%, rising to 45% in those who had frozen their eggs before the age of 36.

‘These are results comparable with those nationally recorded in routine IVF,’ said Professor Nick Macklon, senior author of the study and Medical Director of the London Women’s Clinic. ‘The results are also comparable with those reported from other similar studies in the USA, suggesting that the doubts still commonly expressed about the reliability of egg freezing are misplaced. Taken together, the results appear consistent, predictable and reassuring.’(2)

What has this and other studies told us so far:

The number of women seeking egg-freezing treatment for personal reasons is increasing; in this single-centre study annual patient numbers rose from 150 women in 2015 to more than 800 in 2022.
However, the number of women returning to thaw their frozen eggs remains quite low and steady; only 299 of 2171 patients freezing their eggs returned and completed 332 thaw treatment cycles. Thus, the return rate was 14%, a rate similar to that found in other studies.
Overall, around one quarter of those who fertilised their thawed eggs and transferred them as ‘fresh’ embryos had a baby; the overall cumulative live birth rate, calculated from further frozen embryo transfers was 36% (and 57% in patients who had stored their eggs when aged under 35).
When all eggs were thawed, fertilised and embryos frozen (‘freeze-all’), live birth rate reached 30% for each frozen/thawed embryo transfer.
The success rate in freeze-all cycles was considerably improved for those who chose to have their embryos screened for chromosome abnormalities (PGT-A). Indeed, across all ages the use of PGT-A was associated with a live birth rate double that found with freeze-all treatments with an untested embryo (40% vs 21%). Indeed, all live births in women aged 40 or over were from an embryo which had been screened as chromosomally normal.
The mean age at which the ‘thaw’ patients froze their eggs was 37.6 years; the age at which they returned to thaw and use their eggs was 40 years with an overall average storage period of 24 months.

‘These are encouraging results for those considering freezing their eggs for future use,’ said Professor Macklon. ‘Current consensus based on these and other results would be that 10 to 15% of patients who originally froze their eggs in their later thirties will return to thaw and use them when they are, on average, between 40 and 42 years old.’

The results also challenge the sceptical perception of egg freezing, which may arise from dated studies. The UK regulator, the Human Fertilisation and Embryology Authority (HFEA), for example, recently warned that ‘when looking at success rates for frozen eggs, numbers tend to be quite low’. However, the results from this large study reflect outcomes which are robustly recorded and analysed, and comparable with those of fresh single embryo transfers in IVF when age and egg quality and quantity are taken into account.

‘It thus seems reasonable to conclude,’ said Professor Macklon, ‘that based on these results and those of other studies egg freezing and thawing can provide a very real opportunity for women to achieve pregnancy and live birth at a time of their choosing. With consistency in results, patient expectations can be managed similarly to all IVF treatments. An assessment of age and embryo quality can help estimate the potential outcomes of treatment.’

Notes

Shah T, Garratt J, Mclaughlin A, et al. Clinical outcomes of vitrified-warmed autologous oocyte cycles with 15-year follow-up at a single UK centre: consistent and predictable results. Reprod Biomed Online 2024; https://doi.org/10.1016/j.rbmo.2024.104376
For comparative purposes, the results of this study were analysed alongside two others:
- Blakemore JK, Grifo JA, DeVore SM, et al. Planned oocyte cryopreservation - 10-15-year follow-up: return rates and cycle outcomes. Fertil Steril 2021; 115: 1511–1520. https://doi.org/10.1016/j.fertnstert.2021.01.011
- Kawwass JF, Crawford S, Hipp HS. Frozen eggs: national autologous oocyte thaw outcomes. Fertil Steril 2021; 116: 1077–1084. https://doi.org/10.1016/J.FERTNSTERT.2021.05.080
National statistics from the UK, as reported by the HFEA, describe egg and embryo storage cycles as ‘the fastest growing fertility treatments in the UK’, adding that egg freezing treatments increased from 373 cycles in 2011 to 4215 cycles in 2021. The technique has been facilitated by improvements in freezing technology and the uptake of fast-freezing vitrification. Ice crystal formation in earlier slow-freezing methods was found to cause damage to cells; survival rates from vitrified/thawed have been found above 90% in recent studies. Studies suggest there are two principal reasons for egg freezing: to preserve fertility ahead of toxic treatment such as chemotherapy; and electively to postpone the opportunity for pregnancy to a later date

* RBM Online, founded by Professor Sir Robert Edwards in 2000, is a monthly peer-reviewed journal covering the full range of human reproductive health and disease, including basic and translational science, embryology, ART, infertility, male reproduction, periconception and pregnancy, reproductive health and the social implications of fertility care.

* For more information on this press release and the published paper, please contact:
Duncan Nicholas, RBM Online Development Editor
dev.editor@rbmonline.com
https://linktr.ee/rbmo

JOURNAL

Reproductive BioMedicine Online

DOI

10.1016/j.rbmo.2024.104376

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Human embryos

ARTICLE TITLE

Clinical outcomes of vitrified-warmed autologous oocyte cycles with 15-year follow-up at a single UK centre: consistent and predictable results

ARTICLE PUBLICATION DATE

18-Jul-2024

Montana State researcher studies nano-scale materials that mimic enzymes to convert CO2 into chemical building blocks

The work could reduce carbon dioxide in the atmosphere

MONTANA STATE UNIVERSITY

BOZEMAN — Montana State University researcher James Crawford recently published a collaborative paper with the National Renewable Energy Laboratory that marks a step forward in their quest for what he calls a “holy grail” of chemistry: converting the greenhouse gas carbon dioxide into chemical building blocks which could be used to create myriad other materials.

That paper, “High Selectivity Reactive Carbon Dioxide Capture over Zeolite Dual-Functional Materials,” was published in the June 7 issue of the scientific journal ACS Catalysis. An atom-scale illustration of the carbon dioxide conversion process is featured on the front cover of the journal.

“We have successfully captured carbon dioxide then converted it into methane and carbon monoxide using functionalized microporous materials,” said Crawford, an assistant professor of chemical and biological engineering in MSU’s Norm Asbjornson College of Engineering. “Methane is a drop-in energy resource compatible with existing natural gas infrastructure. Carbon monoxide has a bad reputation but turns out to be an essential reactant in generating synthetic fuels and chemicals.”

The element carbon is found in all living things. It’s the second most abundant element in the human body and the fourth most in the universe. It’s found in biofuels, chemicals, textiles and building materials. It’s also a titular element in carbon dioxide, commonly known as CO2, which makes up less than 1% of Earth’s atmosphere. In addition to being exhaled byhumans, the colorless, odorless, heat-trapping gas is one byproduct of burning fossil fuels like oil, natural gas, gasoline and coal.

Existing methods for removing carbon dioxide from the atmosphere mostly result in storing the gas, rather than converting it into new products.

“What we’re trying to do is introduce another way to capture CO2 by locking it up with chemical bonds,” said Crawford, who is also affiliated with MSU’s Energy Research Institute and the Center for Biofilm Engineering. “If you can convert atmospheric gases like carbon dioxide and water into carbon monoxide and hydrogen, you can then combine them to make pretty much any hydrocarbon.”

Hydrocarbons are organic compounds composed entirely of hydrogen and carbon, which makes them useful as the building block for many chemical compounds and materials.

“Biological catalysts, or enzymes, have been upcycling atmospheric gases for billions of years,” he said. “My group is interested in learning about enzymes and copying their function in robust, solid-state catalysts. This would enable their use in harsh industrial processes.”

His team is interested in materials that can selectively wick CO2 from the air and enable the reactions that change the chemical identity of the molecule. “These catalysts must have CO2 attachment sites, as well as reactive structures that permit chemical reconstruction to take place,” Crawford said.

This requires materials with customizable, nano-scale structures, with dimensions measured in billionths of a meter. He is interested in two materials specifically: zeolites, which are ceramic-like materials, and metal-organic frameworks, which have metal nodes connected with organic linkers. Both materials have micropores and chemical “tunability” to create CO2 capture and conversion sites.

“We generate zeolites and metal-organic frameworks in the lab using a process that combines solvents, heat and pressure to drive the formation of our catalysts,” Crawford said.

Building on these emerging technologies, Crawford, who earned a bachelor’s degree in chemical and biological engineering at MSU before getting his doctorate from the Colorado School of Mines, said he hopes his research will one day lead to designing more efficient nano-catalysts with “biomimetic” properties, meaning they mimic biological processes.

“Biology has figured a lot of this out,” Crawford said. “We are making biomimetic materials that will, one day, be able to steer the CO2 conversion process to generate the chemicals we need the most.”

JOURNAL

ACS Catalysis

DOI

10.1021/acscatal.4c01340

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

High Selectivity Reactive Carbon Dioxide Capture over Zeolite Dual-Functional Materials

Can doomscrolling trigger an existential crisis?

FLINDERS UNIVERSITY

Can doomscrolling trigger an existential crisis?

In a world first study on the impact of doomscrolling from an existential perspective, Flinders University researchers warn that habitual checking of disturbing stories on social media is linked with changes to how we view humankind and the meaning of life.

Doomscrolling is where people spend a lot of time scrolling through traumatic news on social media such as shootings, terrorism and conspiracies, often to the point where it becomes addictive.

The new study reveals that doomscrolling makes people more likely to feel suspicious and distrustful of other people and form the impression that life lacks meaning.

“Doomscrolling can have some dire consequences on our mental health and wellbeing leaving us feeling stress, anxiety, despair and questioning the meaning of life,” says lead author, Mr Reza Shabahang from the College of Education, Psychology and Social Work.

“Viewing negative news on social media has become a source of vicarious trauma, where someone has a negative psychological impact even though they did not experience the trauma themselves.

“By being exposed to images and information about traumatic events, people have been found to experience symptoms similar to post-traumatic stress disorder (PTSD) such as anxiety and despair.”

Researchers surveyed 800 university students from two distinctly diverse cultures, an Eastern collective culture (Iran) and a Western individualistic culture (the United States), to explore how excessive negative news consumption on social media can impact their thoughts and feelings relating to their existence.

Participants were asked to respond on how often they doomscrolled through social media, how anxious they felt about their existence, whether they believed that the world is a fair place, and how they felt about humanity.

“We wanted to see if there were any connections between doomscrolling and subsequent thoughts and feelings about humankind and the importance of life,” says Mr Shabahang.

Doomscrolling was associated with existential anxiety - worries about their existence, life and death - in both Iranian and American samples and emerged as a significant predictor of misanthropy - dislike of people - in the Iranian sample.

“When we're constantly exposed to negative news and information online, it can threaten our beliefs when it comes to our own mortality and the control we have over our own lives.

“Moreover, doomscrolling can negatively affect how we view the people and world around us,” he says.

Mr Shabahang says that the study is a timely reminder to be mindful of our online habits and to take regular breaks from social media and exposure to negative news.

“We suggest that people pay attention to how much time they are spending on social media and to be aware of the impact it is having on their emotions, thoughts and feelings, especially when it comes to negative news and events,” he says.

“It’s a good idea to keep track of how much time you spend doomscrolling and start making changes to reduce that time if it’s problematic.

“By becoming more aware of our online habits, such as doomscrolling, and taking small steps to address them, it could help with improving our overall mental wellbeing,” he adds.

The paper, Doomscrolling evokes existential anxiety and fosters pessimism about human nature? Evidence from Iran and the United States by Reza Shabahang, Hyeyeon Hwang, Emma F. Thomas, Mara S. Aruguete, Lynn E. McCutcheon, Gábor Orosz, Abbas Ali Hossein Khanzadeh, Benyamin Mokhtari Chirani, Ágnes Zsila was published in Computers in Human Behavior Reports Journal. DOI: 10.1016/j.chbr.2024.100438

JOURNAL

Computers in Human Behavior Reports

DOI

10.1016/j.chbr.2024.100438

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Doomscrolling evokes existential anxiety and fosters pessimism about human nature? Evidence from Iran and the United States

Rural belts around cities can reduce urban temperatures by up to 0.5°C

UNIVERSITY OF SURREY

The key to cooling ‘urban heat islands’ may lie in the countryside, according to a new study from scientists at the University of Surrey and Southeast University (China).

Using 20 years of data, researchers showed how nearby rural areas could bring a city’s temperature down. The biggest cooling effects happen where the rural ring around a city extends for at least half the city’s diameter.

Professor Shi-Jie Cao, the lead author and visiting professor at the University of Surrey’s Global Centre for Clean Air Research (GCARE), said:

“We often focus on how green spaces, wetlands or waterways can cool down cities. Yet, urban land is precious, and these measures can be hard to find space for. We have now shown how land use outside a city can make a big difference to temperatures downtown.
“Our findings allow us to make quite specific recommendations. We found that urban over-heating was mitigated more by joining up patches of rural land, planting more woodland scattered around a city, and by having fewer, bigger lakes rather than lots of little bodies of water.

As warm air rises in a city, it creates a layer of low pressure close to the ground. This sucks cooler air in from surrounding rural areas. This process is greatly shaped by the size of a city, and the land cover of neighbouring rural areas.

To find out exactly how, scientists compared the areas around 30 Chinese cities between 2000-2020. Satellite data told them how warm the ground was, and how the land was used.

Professor Prashant Kumar, one of the authors of the study, founding director of GCARE and co-director of Surrey’s Institute of Sustainability, said:

“We already suspected that belts of rural land around a city could help cool down the urban centre. Now, thanks to our detailed analysis, we can say which forms of land use lead to the biggest effects.
“We hope planners and governments can use our findings to help urban communities become more resilient against rising global temperatures. Our findings show that if we want to cool our cities down, we need a joined-up approach between urban and rural planning.”

The study is published in the journal Nature Cities.

JOURNAL

Nature Cities

DOI

10.1038/s44284-024-00091-z

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Mitigating urban heat island through neighboring rural land cover

Study shows new efficiency standards for heavy trucks could boost energy use

Peer-Reviewed Publication

UNIVERSITY OF COLORADO AT BOULDER

Deliveries are getting faster than ever in the U.S., but the faster movement of goods is undercutting the country’s climate progress.

In a new study published July 18 in the journal Nature Energy, a CU Boulder researcher and his collaborator estimate that federal regulations aimed at enhancing heavy-duty trucks’ energy efficiency could be as much as 20% less effective than policymakers initially anticipated.

That’s because the regulations make trucking cheaper. As a result, more shippers will likely switch from using less energy-intensive rail transportation to using more energy-intensive trucks to ship goods.

“We were surprised to see how big of an impact the change in shipping decisions has on our energy use,” said Jonathan Hughes, the paper’s corresponding author and professor in the Department of Economics at CU Boulder. “Increasing vehicles’ energy efficiency is very costly for truck makers, so it’s important to know how much benefit we can get realistically from these costly regulations.”

The rebound effect

In economics, increased consumption due to improved efficiency and reduced costs is known as the rebound effect.

For example, if using an air conditioner consumes much more electricity than using a fan, many people will stick to the fan. But when air conditioners become more efficient, and cooling becomes cheaper, more people will switch to air conditioners. This behavior change would increase overall energy consumption.

Hughes and his collaborators wanted to study the extent of the rebound effect in the freight sector.

“When we think about the challenges in energy and climate change issues, freight transportation is a big, important sector that hasn't received enough attention,” Hughes said.

The freight sector, which includes transportation of goods by truck, train, ship and airplane, represents approximately 10% of total U.S. energy consumption. Freight movement contributes to 27% of the country’s greenhouse gas (GHG) emissions from the transportation sector, which is the largest source of emissions in the U.S.

The majority of emissions from the freight sector come from trucking, which saw a 76% increase in GHG emissions since 1990.

In a bid to reduce emissions and avoid the worse consequences of climate change, the U.S. Environmental Protection Agency (EPA) has rolled out a series of regulations to improve heavy-duty vehicles’ energy efficiency since 2011. These rules require newly manufactured trucks to achieve better mileage using less fuel and emit less GHG.

In March, the EPA announced the strictest-ever fuel economy standards, aiming to prevent 1 billion metric tons of GHG emissions by 2055.

But while these regulations make trucks more energy-efficient, they also make trucking cheaper by reducing fuel costs. As a result, many shippers may opt to transport their goods by truck instead of rail, because trucks can reach destinations faster, allowing for quicker product sales. The authors note that trucks consume significantly more fuel than rail to transport the same amount of goods over the same distance.

Unintended consequence

Hughes and his collaborator, James Bushnell of University of California at Davis, used newly released data on goods movement from the U.S. Census Bureau to estimate the rebound effect in the freight sector. Using a computer simulation, they calculated the amount of energy saved if the EPA regulations increased new trucks’ fuel efficiency by 5%, which is roughly what the standard is today.

Under this scenario, the team found that the regulations had the potential to save 674 million gallons of gas per year. But when they factored in the increased share of goods forecasted to be shipped by truck due to the rebound effect, the regulations would only save 497 million gallons of fuel—still a significant amount, but 26% less than previously estimated.

Some industries, such as the chemical, animal feed, alcohol and petroleum industries are particularly sensitive to reductions in fuel costs and would likely experience the largest rebound effect, Hughes said.

Accounting for all modes of freight transportation, the team estimated that the rebound effect in the freight sector would reduce the total fuel savings from federal regulations by 20%.

“We show that if we make transportation much more efficient, either through increasing energy efficiency or automation that reduces labor costs, we will likely wind up consuming more energy than we thought we would,” said Hughes.

While the paper focused on the freight sector, Hughes added a similar rebound effect could also exists in the retail sector, which includes businesses like Amazon.

“These regulations that help reduce transportation costs certainly benefit consumers, because we can now purchase things at lower prices. But we show that these rules can be somewhat counterproductive in terms of achieving our climate change and energy goals,” Hughes said.

Hughes said making fuel pricier and transportation more expensive through programs like taxing carbon emissions would be a more effective way to reduce energy use in transportation. But those types of policies tend to be very difficult to get political support for, he added.

“This study shows we should get a more complete picture of the impacts these regulations might have, so we don’t end up adopting policies that lead to unintended negative effects,” he said.

JOURNAL

Nature Energy

DOI

10.1038/s41560-024-01568-w

Minerals play newly discovered role in Earth’s phosphorus cycle

New research finds that iron oxide in soils can recycle phosphorus from organic matter

Peer-Reviewed Publication

NORTHWESTERN UNIVERSITY

Phosphorus illustration — IMAGE:
ILLUSTRATION OF PHOSPHORUS CLEAVAGE FROM DIFFERENT BIOMOLECULES ON THE SURFACE OF NATURAL IRON OXIDE PARTICLES.
view more
CREDIT: ARISTILDE RESEARCH GROUP/NORTHWESTERN UNIVERSITY

Northwestern University-led researchers have discovered a new way that nature cycles phosphorus, a finding that uncovers a missing piece of Earth’s puzzling phosphorus cycle.

The research will be published on Thursday (July 18) in the journal Nature Communications.

A critical nutrient for plant growth, phosphorus is a non-negotiable component of fertilizers. Without it, farmers cannot ensure plant health and boost crop yields. Understanding Earth’s phosphorus cycle, therefore, is important for protecting the global food supply.

Although organic forms of phosphorus are abundant in soils, plants and microbes need inorganic phosphorus to spur their own growth. In the organic form, phosphorus is connected to carbon atoms directly or indirectly, using oxygen as a bridge. So, plants and microbes secrete enzymes to break the carbon bond in organic phosphorus to generate bioavailable inorganic phosphorus.

While current understanding of the phosphorus cycle assumes that only enzymes from plants and microbes drive this transformation, the new Northwestern study shows there is another way. Iron oxide, a naturally occurring mineral in soils and sediments, can perform the reaction that transforms organic phosphorus to generate the inorganic form. Surprisingly, the researchers also found that iron oxide minerals recycle phosphorus at a similar rate as reported for enzymes in soils.

“Currently, the main source of phosphorus for fertilizers is from mining,” said Northwestern’s Ludmilla Aristilde, who led the work. “It’s a finite resource that we eventually will run out of. According to some estimates, we might run out in as soon as 50 years or in a couple hundred years. We are looking into ways to leverage nature-based solutions for phosphorus recycling because we cannot have food security without it. But, before we can do that, we need to understand the underlying mechanisms of natural phosphorus recycling. We found that minerals play an important, and previously unknown, role in the process.”

An expert in the dynamics of organics in environmental processes, Aristilde is an associate professor of environmental engineering at Northwestern’s McCormick School of Engineering. She also is a member of the Center for Synthetic Biology, International Institute for Nanotechnology and Paula M. Trienens Institute for Sustainability and Energy. Jade Basinski, a Ph.D. student in Aristilde’s laboratory, is the paper’s first author. Analeise Klein and Wiriya Thongsomboon, former postdoctoral researchers in the laboratory, are contributing authors.

Looking beyond biology

When dead vegetation or microbes decay in the soil, they leave behind a number of nutrients, including DNA and RNA, which are important classes of organic phosphorus. Microbes and living plants use enzymes to cleave phosphorus from nucleotides — structural components in DNA and RNA — in decaying organic matter to make it available as a recycled nutrient. Until now, most researchers assumed using enzymes was nature’s only mechanism for recycling organic phosphorus.

Aristilde and her collaborators, however, decided to explore whether another mechanism might be at play.

“Findings from field studies on the environmental dynamics of phosphorus suggested to consider mechanisms beyond biology for the transformation of organic phosphorus in sediments,” Aristilde said. “My group began looking at minerals, specifically iron oxides, because they are known to be able to serve as catalysts.”

The case of the missing phosphorus

In laboratory experiments, Aristilde and her team studied the fate of phosphorus in soils and sediments containing iron oxide minerals. After running multiple experiments and analyses, researchers found transformation products from the reaction in the solution. But part of the inorganic phosphorus was curiously missing.

Because iron oxide is known to trap phosphorus, the team wanted to examine the minerals more closely. To do so, they used a specialized X-ray technique at the Stanford Synchrotron Radiation Lightsource to solve the mystery.

“Lo and behold, we found that the phosphorus was clinging to the surface of the iron oxide,” Aristilde said. “Basically, the minerals can recycle phosphorus from DNA and RNA molecules. But not all organic phosphorus is released in the solution because it is stuck to the surface. The X-ray technique allowed us to find that a big fraction of the newly generated inorganic phosphorus was associated with iron oxides.”

Otherworldly insights

Aristilde’s team then measured how — and how much — inorganic phosphorus was produced from nucleotides. The researchers discovered that minerals recycle phosphates at a rate comparable to biology.

“We did not expect the rates to be so comparable to those reported for soil enzymes,” Aristilde said. “It changes the way we think about how phosphorus is recycled.”

Not only will the new information expand the way we think about how phosphorus cycles on our planet, it also can provide insights about our neighboring planets.

“Mars is red because it’s full of iron oxides,” Aristilde said. “If there is inorganic phosphorus found to be trapped in them, it is reasonable to ask: ‘Could this phosphorus have an organic origin from life?’”

The study, “Unraveling iron oxides as abiotic catalysts of organic phosphorus recycling in soil and sediment matrices,” was supported by the U.S. Department of Energy (award number DE-SC0021172).

JOURNAL

Nature Communications

DOI

10.1038/s41467-024-47931-z

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Unraveling iron oxides as abiotic catalysts of organic phosphorus recycling in soil and sediment matrices

ARTICLE PUBLICATION DATE

18-Jul-2024