Cannabis users no less likely to be motivated or able to enjoy life’s pleasure

Peer-Reviewed Publication

UNIVERSITY OF CAMBRIDGE

Adult and adolescent cannabis users are no more likely than non-users to lack motivation or be unable to enjoy life’s pleasure, new research has shown, suggesting there is no scientific basis for the stereotype often portrayed in the media.

Cannabis users also show no difference in motivation for rewards, pleasure taken from rewards, or the brain’s response when seeking rewards, compared to non-users.

Cannabis is the third most commonly used controlled substance worldwide, after alcohol and nicotine. A 2018 report from the NHS Digital Lifestyles Team stated that almost one in five (19%) of 15-year-olds in England had used cannabis in the previous 12 months, while in 2020 the National Institute on Drug Abuse reported the proportion in the United States to be 28% of 15-16-year-olds.

A common stereotype of cannabis users is the ‘stoner’ – think Jesse Pinkman in Breaking Bad, The Dude in The Big Lebowski, or, more recently, Argyle in Stranger Things. These are individuals who are generally depicted as lazy and apathetic.

At the same time, there has been considerable concern of the potential impact of cannabis use on the developing brain and that using cannabis during adolescence might have a damaging effect at an important time in an individual’s life.

A team led by scientists at UCL, the University of Cambridge and the Institute of Psychiatry, Psychology & Neuroscience at King’s College London carried out a study examining whether cannabis users show higher levels of apathy (loss of motivation) and anhedonia (loss of interest in or pleasure from rewards) when compared to controls and whether they were less willing to exert physical effort to receive a reward. The research was part of the CannTEEN study.

The results are published in the International Journal of Neuropsychopharmacology.

The team recruited 274 adolescent and adult cannabis users who had used cannabis at least weekly over the past three months, with an average of four days per week, and matched them with non-users of the same age and gender.

Participants completed questionnaires to measure anhedonia, asking them to rate statements such as “I would enjoy being with family or close friends”. They also completed questionnaires to measure their levels of apathy, which asked them to rate characteristics such as how interested they were in learning new things or how likely they were to see a job through to the end.

Cannabis users scored slightly lower than non-users on anhedonia – in other words, they appeared better able to enjoy themselves – but there was no significant difference when it came to apathy. The researchers also found no link between frequency of cannabis use and either apathy or anhedonia in the people who used cannabis.

Martine Skumlien, a PhD candidate in the Department of Psychiatry at the University of Cambridge, said: “We were surprised to see that there was really very little difference between cannabis users and non-users when it came to lack of motivation or lack of enjoyment, even among those who used cannabis every day. This is contrary to the stereotypical portrayal we see on TV and in movies.”

In general, adolescents tended to score higher than adults on anhedonia and apathy in both user and non-user groups, but cannabis use did not augment this difference.

Dr Will Lawn, from the Institute of Psychiatry, Psychology and Neuroscience at King’s College London, said: “There’s been a lot of concern that cannabis use in adolescence might lead to worse outcomes than cannabis use during adulthood. But our study, one of the first to directly compare adolescents and adults who use cannabis, suggests that adolescents are no more vulnerable than adults to the harmful effects of cannabis on motivation, the experience of pleasure, or the brain’s response to reward.

“In fact, it seems cannabis may have no link – or at most only weak associations – with these outcomes in general. However, we need studies that look for these associations over a long period of time to confirm these findings.”

Just over half of participants also carried out a number of behavioural tasks. The first of these assessed physical effort. Participants were given the option to perform button-presses in order to win points, which were later exchanged for chocolates or sweets to take home. There were three difficulty levels and three reward levels; more difficult trials required faster button pressing. On each trial the participant could choose to accept or reject the offer; points were only accrued if the trial was accepted and completed.

In a second task, measuring how much pleasure they received from rewards, participants were first told to estimate how much they wanted to receive each of three rewards (30 seconds of one of their favourite songs, one piece of chocolate or a sweet, and a £1 coin) on a scale from ‘do not want at all’ to ‘intensely want’. They then received each reward in turn and were asked to rate how pleasurable they found them on a scale from ‘do not like at all’ to ‘intensely like’.

The researchers found no difference between users and non-users or between age groups on either the physical effort task or the real reward pleasure task, confirming evidence from other studies that found no, or very little, difference.

Skumlien added: “We’re so used to seeing ‘lazy stoners’ on our screens that we don’t stop to ask whether they’re an accurate representation of cannabis users. Our work implies that this is in itself a lazy stereotype, and that people who use cannabis are no more likely to lack motivation or be lazier than people who don’t.

“Unfair assumptions can be stigmatising and could get in the way of messages around harm reduction. We need to be honest and frank about what are and are not the harmful consequences of drug use.”

Earlier this year, the team published a study that used functional magnetic resonance imaging (fMRI) to look at brain activity in the same participants as they took part in a brain imaging task measuring reward processing. The task involved participants viewing orange or blue squares while in the scanner. The orange squares would lead to a monetary reward, after a delay, if the participant made a response.

The researchers used this set up to investigate how the brain responds to rewards, focusing in particular on the ventral striatum, a key region in the brain’s reward system. They found no relationship between activity in this region and cannabis use, suggesting that cannabis users had similar reward systems as non-users.

Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge, said: “Our evidence indicates that cannabis use does not appear to have an effect on motivation for recreational users. The participants in our study included users who took cannabis daily and they were no more likely to lack motivation. However, we cannot rule out the possibility that greater use, as seen in some people with cannabis-use disorder, has an effect.

“Until we have future research studies that follow adolescent users, starting from onset through to young adulthood, and which combine measures of motivation and brain imaging, we cannot determine for certain that regular cannabis use won’t negatively impact motivation and the developing brain.”

This research was funded by the Medical Research Council with additional support from the Aker Foundation, National Institute for Health Research and Wellcome.

Reference

1. Skumlien, M, et al. Anhedonia, apathy, pleasure, and effort-based decision-making in adult and adolescent cannabis users and controls. IJNP; 24 Aug 2022; DOI: 10.1093/ijnp/pyac056
2. Skumlien, M, et al. Neural responses to reward anticipation and feedback in adult and adolescent cannabis users and controls. Neuropsychopharmacology; 6 April 2022; DOI: 10.1038/s41386-022-01316-2

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JOURNAL

The International Journal of Neuropsychopharmacology

DOI

10.1093/ijnp/pyac056 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Anhedonia, apathy, pleasure, and effort-based decision-making in adult and adolescent cannabis users and controls

ARTICLE PUBLICATION DATE

Female genital mutilation/cutting is decreasing but more needs to be done

Peer-Reviewed Publication

PLOS

 

IMAGE: RESEARCHERS ASSESS THE SCOPE OF GLOBAL FEMALE GENITAL MUTILATION view more 

CREDIT: NADINE SHAABANA, UNSPLASH (CC0, HTTPS://CREATIVECOMMONS.ORG/PUBLICDOMAIN/ZERO/1.0/)

An estimated 100 million girls and women of reproductive age across 30 countries have experienced female genital mutilation/cutting (FGM/C), according to a new meta-analysis publishing September 1st in the open access journal PLOS Medicine. The review reports that FGM/C seems to be decreasing in 26 countries for both women and girls, but much work needs to be done in others.

FGM/C is an extreme form of abuse and gender inequality that violates women’s and girls’ human rights. It has lifelong health and economic consequences for women and girls. Stephen J McCall of the American University of Beirut, Lebanon, and colleagues undertook this study to provide a baseline estimate of numbers of women affected and to understand where the data gaps are. The WHO Sustainable Development Goal (SDG) target 5.3 on gender equality refers to FGM/C as a harmful traditional practice and calls for ending it by 2030.

The researchers included 30 studies in their meta-analysis, of which 23 were from the African region, six from the Eastern Mediterranean, and one from South-East Asia. The studies included data from 406,068 women from 30 countries and 296,267 girls from 25 countries. They found that 36.9% of women aged 15-49 and 8.27% of girls aged 0-15 years had experienced FGM/C.

Though the practice is on the decline in most countries, and the SDG target seems attainable, there were several where the decrease was tiny or there was a slight increase. Countries including Egypt, Somalia, Sudan, Indonesia, Guinea, and Mali will not meet the target unless much more work is done to stop FGM/C.

The study accurately estimates the countries included but provides an underestimate of the global picture because of gaps in available published data. These gaps need to be resolved to understand the progress towards SDG 5.3.

McCall adds, “This study found that approximately 100 million women and girls have been subjected to female genital mutilation/cutting globally. However, the number of women and girls impacted is likely to be even higher as many countries do not report on this harmful practice.”

#####

In your coverage, please use this URL to provide access to the freely available paper in PLOS Medicine: http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1004061

Citation: Farouki L, El-Dirani Z, Abdulrahim S, Akl C, Akik C, McCall SJ (2022) The global prevalence of female genital mutilation/cutting: A systematic review and meta-analysis of national, regional, facility, and school-based studies. PLoS Med 19(9): e1004061. https://doi.org/10.1371/journal.pmed.1004061

Author Countries: Lebanon

Funding: The authors received no specific funding for this work.

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JOURNAL

PLoS Medicine

DOI

10.1371/journal.pmed.1004061 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

People

Female managers pay fairer

Peer-Reviewed Publication

KARLSRUHER INSTITUT FÜR TECHNOLOGIE (KIT)

There are two levels of reference for the elementary question of an appropriate remuneration of work: the markets with their structure of supply, demand, and productivity as well as the needs of the employees. Operationally decisive, however, is also what managers are guided by when assessing wages. A study recently published in PLOS ONE by researchers at the Karlsruhe Institute of Technology (KIT) provides new insights into this issue.

"Our study shows that the respective incentive system, work experience, and especially gender have an influence on what wages managers set for their employees," says Nora Szech, professor of political economy at KIT‘s Institute of Economics and author of the study, which was conducted together with David Huber and Leonie Kühl from her team.

With a total of 500 test subjects - divided into "assemblers" and "managers" - the researchers investigated these influencing factors in KIT's KD²Lab: "The assemblers screwed 100 ballpoint pens together and apart - a nerve-racking activity that took more than an hour. The managers determined the appropriate salary for this. They could choose amounts up to 21 euros. Some of the managers were allowed to keep the rest of the 21 euros for themselves; for the other part, the rest of the 21 euros went back into the research pot," says Szech, explaining the experimental scenario.

Here, the gender-related differences proved to be particularly significant: "The managers," says Szech, "kept most of the 21 euros for themselves, if possible; on average, they paid out only 7.59 euros. Without the possibility of self-interest, on the other hand, they set 11.10 euros as pay for the fitters - a difference of 46 percent! Female managers decided much more consistently: "If they could keep the rest of the 21 euros for themselves, they set 8.54 euros as the assembly wage. If the rest of the 21 euros went to research, they considered 9.44 euros to be appropriate," the researcher reports.

"Various studies observe that women make more selfless and moral decisions than men. However, we were shocked at how drastic the discrepancy was here," Szech emphasizes. "Our study shows that diversity in the executive ranks is important if the atmosphere in a company is to be appreciative and wage inequality is to be limited."

Further information

The study, "Setting Adequate Wages for Workers: Managers' work experience, incentive scheme and gender matter," by Nora Szech, Leonie Kühl and David Huber, is published in the online journal PLOS ONE: https://doi.org/10.1371/journal.pone.0271762

Being “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility, and information. For this, about 9,800 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 22,300 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life. KIT is one of the German universities of excellence.

In the portal "Experts of KIT" you will find further contact persons on highlights of research at KIT and current topics.

DOI

10.1371/journal.pone.0271762 

ARTICLE TITLE

Setting adequate wages for workers: Managers’ work experience, incentive scheme and gender matter

Majority of underrepresented early career scientists experience psychological distress; mentoring helps buffer impact

Peer-Reviewed Publication

UNIVERSITY OF PITTSBURGH

 

IMAGE: DR. GRETCHEN WHITE, PHD. view more 

CREDIT: COURTESY OF UNIVERSITY OF PITTSBURGH

PITTSBURGH, Sept. 1, 2022 – Social unrest due to systemic racism is causing early career scientists from underrepresented backgrounds to experience psychological distress, according to new results from a research survey conducted by University of Pittsburgh scientists. Such distress is a red flag as academic institutions nationwide strive to improve diversity. 

But less than a third said social unrest negatively impacted their ability to work, and survey participants were more than twice as likely to say their mentoring relationships were positively, rather than negatively, impacted.  

“Responses to open-ended survey questions made it seem like maybe people had positive feelings about mentoring because they were starting to talk about the racial justice movement and get affirmation of their feelings from their mentors,” said Dr. Gretchen White, assistant professor in Pitt’s School of Medicine and lead author of the study, published in the Journal of Clinical and Translational Science.  

White noted that previous studies have shown the importance of mentorship, when a more experienced person provides guidance and support to someone less experienced, particularly in the workplace.  

“Our findings reinforce the positive impact of mentoring,” she said. “But mentoring isn’t the only answer. I’d be remiss not to emphasize the incredibly detrimental effects of psychological distress. People may have found ways to deal with this stress at work, but we know that early career scientists from underrepresented backgrounds disproportionately leave their careers.” 

The survey was conducted as part of the Building Up a Diverse Biomedical Research Workforce (Building Up) Trial, which is testing approaches – such as mentoring and networking – to improve retention of early career researchers who are underrepresented in the health sciences, including people who identify as Black, Hispanic or female, have disabilities or are from disadvantaged backgrounds. 

A total of 144 early career researchers from 25 academic institutions participated in the survey; 80% were female, 35% were Black and 40% Hispanic.  

Following the survey, the researchers interviewed some participants to better understand the results.  

“Many participants described work environments riddled with overt discrimination and isolation from other persons of color,” said White. “I love science and research, but conducting it in a work environment that is not supportive and sometimes hostile is upsetting and stressful. Being inclusive and having diverse researchers, like myself and others, makes for better science and discovery to benefit society as a whole.” 

#  #  #

About the University of Pittsburgh School of Public Health

Founded in 1948, the University of Pittsburgh School of Public Health is a top-ranked institution of seven academic departments partnering with stakeholders locally and globally to create, implement and disseminate innovative public health research and practice. With hands-on and high-tech instruction, Pitt Public Health trains a diverse community of students to become public health leaders who counter persistent population health problems and inequities. 

www.upmc.com/media

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JOURNAL

Journal of Clinical and Translational Science

DOI

10.1017/cts.2022.445 

ARTICLE TITLE

The Impact of Social Unrest due to Systemic Racism on Underrepresented Post-doctoral Fellows and Early-Career Faculty

Past and present racism linked to excess nonfatal shootings in Baltimore’s most disadvantaged neighborhoods

Study finds doubly disadvantaged neighborhoods experienced a disproportionate share of firearm injuries from 2015 to 2019

Peer-Reviewed Publication

JOHNS HOPKINS UNIVERSITY BLOOMBERG SCHOOL OF PUBLIC HEALTH

A new study led by researchers at the Johns Hopkins Bloomberg School of Public Health links historic redlining, coupled with ongoing segregation by race and income, to 38 percent of the nonfatal shooting rate in Baltimore city’s most disadvantaged neighborhoods between 2015 to 2019.

For their analysis, the researchers looked at two examples of structural racism: redlining and racialized economic segregation. Redlining is a term used to describe discriminatory policies that systematically deny or increase the costs of mortgages, insurance, and loans based on the percentage of the neighborhood’s residents who are Black or other racial or ethnic minorities.

For many decades, lending institutions redlined low-income neighborhoods, which often had large populations of people of color, classifying them as investment risks. The practice resulted in neighborhoods with lower home values and fewer services and resources. Combined racial and economic segregation, also known as racialized economic segregation, measures current factors, including race and income.

The analysis found redlining, coupled with ongoing segregation, is linked to 10 additional nonfatal shootings occurring in Baltimore’s most disadvantaged neighborhoods per year, per 10,000 residents.

The study was published online September 1 in Injury Prevention.

“These communities of color are doubly impacted. They have been redlined in the past and are underserved now,” says the paper’s lead author, Mudia Uzzi, a doctoral candidate in the Bloomberg School’s Department of Health, Behavior and Society. “Health equity and racial justice need to be prioritized when developing gun violence prevention policies and interventions.”

More than 5,000 nonfatal shootings have occurred in Baltimore since 2015, according to law enforcement records. These nonfatal shootings present many health and safety problems, including physical injuries, health care costs, and mental health issues like stress, grief, and trauma.

For their study, the researchers drew from nonfatal shooting data from the Baltimore Police Department and population data from the U.S. Census Bureau’s American Community Survey (ACS). The researchers then calculated the annual nonfatal shooting rate for 2015–2019 in 149 census tracts across Baltimore city, scaled per 10,000 residents. The researchers found that nonfatal shootings across Baltimore’s neighborhoods were unevenly distributed.

To determine levels of historical redlining in each census tract, they examined the 1937 Baltimore Home Owners’ Loan Corporation map, which designated specific areas—many of which were historically Black neighborhoods—as “hazardous” for investment. The researchers then calculated what are known as Index of Concentration at the Extremes (ICE) scores, a measure that factors in geographic and social polarization. These researchers used this measure to quantify the concentration of households in census tracts that are most socioeconomically advantaged—non-Hispanic white households with an income over $100,000—versus most socioeconomically disadvantaged—non-Hispanic Black households with incomes below the federal poverty line of $25,000.

These scores were used to identify contemporary levels of racialized economic segregation in each census tract, utilizing the median household income data from the 2019 Census survey.

The researchers categorized 149 census tracts in Baltimore into four groups of neighborhoods based on their rates of both historical redlining and contemporary racialized economic segregation. Sustained advantaged neighborhoods had low rates of historical redlining and high ICE scores, indicating high, contemporary socioeconomic status and low segregation. Sustained doubly disadvantaged neighborhoods had high rates of historical redlining, high segregation, and low ICE scores.

Out of the 149 tracts, 38 percent were doubly disadvantaged over a sustained period and 20 percent were classified as sustained advantaged. The researchers observed that in sustained disadvantaged neighborhoods, 28 residents out of 10,000 experienced nonfatal shootings each year compared with 4 residents in sustained advantaged neighborhoods. This represents 24 more nonfatal shootings per 10,000 residents per year in sustained disadvantaged neighborhoods versus sustained advantaged neighborhoods.

“There is a pernicious pathway from structural racism to the devastating health consequences of gun violence in Black communities,” says Carl Latkin, PhD, vice chair of the Bloomberg School’s Department of Health, Behavior and Society and the paper’s senior author. “This dynamic is part of a feedback loop of disinvestment, poverty, and violence that should be addressed by enacting meaningful gun control policies and investing in Black urban communities.”

“An intersectional analysis of historical and contemporary structural racism on non-fatal shootings in Baltimore, Maryland” was written by Mudia Uzzi, Kyle Aune, Lea Marineau, Forrest Jones, Lorraine Dean, John Jackson, and Carl Latkin.

# # #

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JOURNAL

Injury Prevention

ARTICLE TITLE

An intersectional analysis of historical and contemporary structural racism on non-fatal shootings in Baltimore, Maryland

Black-owned restaurants impacted disproportionately by COVID-19

Using multiple sources of geospatial big data, researchers confirmed that Black-owned restaurants saw a greater disparity in lost patronage than other restaurants.

Peer-Reviewed Publication

UNIVERSITY OF ARKANSAS

 

IMAGE: GEOSCIENCES PROFESSOR XIAO HUANG view more 

CREDIT: UNIVERSITY RELATIONS

It’s well established that people of color suffered higher mortality rates and worse health outcomes during the COVID-19 pandemic than white people. But the economic consequences of COVID-19 are still being determined.

Xiao Huang, a U of A assistant professor with the Department of Geosciences and the Center for Advanced Spatial Technologies, is attempting to provide some clarity. He was the lead author on a recent study that found Black-owned restaurants were hit harder by the pandemic than restaurants whose ownership was otherwise unknown.

The study utilized geospatial big data, which can include things like Yelp reviews or geo-tagged tweets, to do a longitudinal quantitative analysis of Black-owned businesses through the pandemic year of 2020. The researchers focused on 20 U.S. cities to observe differences among various geographic locations and to ensure spatial representativeness.

Yelp reviews were especially helpful because they might include the “Black-owned” label with associated businesses, or the identifier was mentioned in reviews. Otherwise, there was no systematic way to verify Black-owned businesses. Yelp listings were then cross-referenced with visitation records collected by SafeGraph, a company that collects visitation patterns on points of interest through an estimated 45 million mobile devices.

Overall, the researchers found there were statistically significant differential impacts between Black-owned and “ownership-unreported” restaurants throughout the 20 cities, primarily measured by relative declines in visits. New Orleans and Detroit showed the greatest disparities, while New York City showed the least.

Due to the number of cities involved and the overall time period examined, which saw fluctuations in the number of visitors at various stages of the pandemic, broader explanations are harder to draw. Early in the pandemic, Black-owned businesses actually outpaced ownership-unreported businesses, peaking in June and July, but eventually declines led to larger disparities between them and ownership-unknown businesses.

While Huang and his co-authors concede there were limitations to the data they were able to collect — for instance, visits of less than four minutes were not included in the SafeGraph dataset, which excluded take-out and delivery services — they were still able to make an apples-to-apples comparison between visits to Black-owned and ownership-unreported businesses. As such, they feel the data help make the case for a more comprehensive study to identify why Black-owned businesses suffered disproportionately. They also argue for better place-based responses to support Black-owned businesses that may be struggling disproportionately, such as implementing a rainy-day fund.

“The voices of the minority, the vulnerable and others who have been disproportionately affected by the COVID-19 pandemic need to be heard,” Huang commented. “As a scholar, I will continue collecting evidence that helps reveal the negative impacts of the COVID-19 pandemic on them.”

Bo Zhao, associate professor of geography at the University of Washington and corresponding author on the paper, added, “Big tech plays an increasingly influential role in almost every aspect of our everyday life, especially in today’s economic recovery, and the Black-owned labeling campaign appears to be well-intended.”

“But what have been the consequences?” Zhao asked. “As allyship to minorities has become a core value of our time, how can big tech become a better and more inclusive ally? This research provides a timely case study.”

The article, titled “Black businesses matter: A longitudinal study of black-owned restaurants in the COVID-19 pandemic using geospatial big data,” was published in the Annals of the American Association of Geographers. Huang and Zhao’s co-writers included Xiaoqi Bao, Zhenlong Li and Shaozeng Zhang.

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JOURNAL

Annals of the Association of American Geographers

DOI

10.1080/24694452.2022.2095971 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Black Businesses Matter: A Longitudinal Study of Black-Owned Restaurants in the COVID-19 Pandemic Using Geospatial Big Data

 

PLOS Global Public Health editors call for embedding Indigenous self-determination, with respect to researchers, knowledge, ethics, and processes, into all stages of research, to decolonize global health

Peer-Reviewed Publication

PLOS

 

IMAGE: A MAP OF THE WORLD. view more 

CREDIT: GERD ALTMANN, PIXABAY, CC0 (HTTPS://CREATIVECOMMONS.ORG/PUBLICDOMAIN/ZERO/1.0/)

PLOS Global Public Health editors call for embedding Indigenous self-determination, with respect to researchers, knowledge, ethics, and processes, into all stages of research, to decolonize global health

###

Article URL: https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0000999

Article Title: Reconciliation and Indigenous self-determination in health research: A call to action

Contact: Pamela Roach, pamela.roach@ucalgary.ca, Ph.: +1 403 805 2254

Author Countries: Canada, Australia

Funding: The authors received no specific funding for this work.

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JOURNAL

PLOS Global Public Health

DOI

10.1371/journal.pgph.0000999 

ARTICLE TITLE

Reconciliation and Indigenous self-determination in health research: A call to action

ARTICLE PUBLICATION DATE

1-Sep-2022

FRANKENGENE

Belgian stem cell biologists create new human cell type for research

Their model cells helps to study early embryonic development

Peer-Reviewed Publication

KU LEUVEN

 

IMAGE: FROM LEFT TO RIGHT: BRADLEY BALATON, THI XUAN AI PHAM, AMITESH PANDA, AND VINCENT PASQUE. view more 

CREDIT: KU LEUVEN

Professor Vincent Pasque and his team at KU Leuven have managed to generate a new type of human cell in the lab using stem cells. The new cells closely resemble their natural counterparts in early human embryos. As a result, researchers can now better study what happens just after an embryo implants in the womb. The findings were published in Cell Stem Cell. 

When all goes well, a human embryo implants in the womb about seven days after fertilisation. At that point, the embryo becomes inaccessible for research due to technical and ethical limitations. That is why scientists have already developed stem cell models for various types of embryonic and extraembryonic cells to study human development in a dish.

Vincent Pasque's team at KU Leuven has developed the first model for a specific type of human embryo cells, extraembryonic mesoderm cells. Professor Pasque: "These cells generate the first blood in an embryo, help to attach the embryo to the future placenta, and play a role in forming the primitive umbilical cord. In humans, this type of cell appears at an earlier developmental stage than in mouse embryos, and there might be other important differences between species. That makes our model especially important: research in mice may not give us answers that also apply to humans.” 

The researchers made their model cells from human stem cells that can still develop into all cell types of an embryo. The new cells closely resemble their natural counterparts in human embryos and are therefore a good model for that specific cell type. 

"You don't make a new human cell type every day," Pasque continues. "We are very excited because now we can study processes that normally remain inaccessible during development. In fact, the model has already enabled us to find out where extraembryonic mesoderm cells come from. In the longer term, our model will hopefully also shed more light on medical challenges such as fertility problems, miscarriages, and developmental disorders."

CAPTION

Fluorescent microscopy image of the new cells (extraembryonic mesoderm cells) and placenta progenitor stem cells. The new cells are marked in red, and cells corresponding to placental stem cells are shown in green. The DNA (nucleus) of each cell is shown in blue.

CREDIT

Amitesh Panda (KU Leuven)

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JOURNAL

Cell Stem Cell

DOI

10.1016/j.stem.2022.08.001 

METHOD OF RESEARCH

Experimental study

ARTICLE TITLE

Modeling human extraembryonic mesoderm cells using naive pluripotent stem cells

ARTICLE PUBLICATION DATE

1-Sep-2022

Microbial communities stay healthy by swapping knowledge

High levels of horizontal gene transfer could help researchers engineer useful microbiomes independent of unstable population dynamics

Peer-Reviewed Publication

DUKE UNIVERSITY

 

IMAGE: LINCHONG YOU, PROFESSOR OF BIOMEDICAL ENGINEERING AT DUKE UNIVERSITY view more 

CREDIT: DUKE UNIVERSITY

DURHAM, N.C. – Biomedical engineers at Duke University have demonstrated a microbial community phenomenon that essentially equates to teaching neighbors how to complete necessary tasks by ripping out and sharing parts of the brain.

The process allows microbiomes to keep themselves and their environments healthy and could help scientists create robust, bespoke microbial systems for applications ranging from cleaning toxins from the environment to producing biofuel and other consumer products.

The research appears online September 1 in the journal Nature Chemical Biology.

Large, complex microbial communities live everywhere in the world, from rivers and mountains to humans and houses. But whether comparing microbiomes on snowcapped peaks in Asia or within the stomachs of identical human twins, the composition of species within these communities can vary widely.

No matter how different these microbiomes may appear to be on the surface, if they live in similar environments, they’re likely going to fill the same functions. One way of evaluating what processes they’re carrying out is focusing on the genes that encode the functions rather than the species themselves.

“If you count the number of the copies of genes that encode some function, their numbers can remain stable even if the species composition of the community changes dramatically,” said Lingchong You, professor of biomedical engineering at Duke. “One important route to this level of stability is through horizontal gene transfer.”

Horizontal gene transfer is the process by which bacteria constantly share genetic recipes for new abilities by swapping packages of genetic material called plasmids. At a conceptual level, it’s not entirely dissimilar to creating a copy of a collection of neurons that knows how to make lasagna, ripping it out of your head and giving it to a friend to use.

In the new paper, You and his colleagues show that this gene transfer plays an essential role in keeping microbiomes healthy and ensuring critical tasks are completed. Starting with two different species of bacteria, the researchers controlled the levels of horizontal gene transfer and showed that higher rates led to more stable concentrations of these genes.

The team then constructed a community of up to 72 bacteria swapping up to 13 different genes simultaneously and measured the genes’ stability. As with the simpler model, the genes that were traded more frequently maintained a steadier level within the microbiome as a whole.

“These results have been speculated about before, but never quantified within living communities,” You said. “The other route to this level of redundancy is to have multiple species that can perform the same function. But a high level of horizontal gene transfer is a much more robust method to achieve the same results.”

Put another way, a construction crew could be extremely resilient to electricians quitting if the plumbers on site also knew how to wire a building. But the same crew would be even more resilient if the remaining electricians could simply transfer their expertise to anyone on the job when needed, no matter their profession.

Moving forward, You hopes to study natural microbial communities to prove definitively that this phenomenon is important to a microbiome’s health outside of a laboratory. He also plans to implement this dynamic division of labor through horizontal gene transfer in engineered microbial systems.

“There are cases where complex metabolic pathways are difficult to engineer in a single bacterial species where it’s easier to have different populations carrying out different steps of the process,” You said. “This study suggests we can implement that strategy through gene transfer so that we don’t have to worry about the specific composition of species. We can just let the community find the best balance for itself while still knowing it will continue to get the job done.”

This research is supported by the National Institutes of Health (R01AI125604, R01EB031869) and the National Science Foundation (MCB-347 1937259).

CITATION: “Horizontal Gene Transfer Enables Programmable Gene Stability in Synthetic Microbiota,” Teng Wang, Andrea Weiss, Ammara Aqeel, Feilun Wu, Allison J. Lopatkin, Lawrence A. David, Lingchong You. Nature Chemical Biology, Sept. 1, 2022. DOI: 10.1038/s41589-022-01114-3

Nature Link: https://www.nature.com/articles/s41589-022-01114-3

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JOURNAL

Nature Chemical Biology

DOI

10.1038/s41589-022-01114-3 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Horizontal Gene Transfer Enables Programmable Gene Stability in Synthetic Microbiota

ARTICLE PUBLICATION DATE

1-Sep-2022

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