Novel Approach to Precisely Control Gas-liquid Taylor Flow Pattern for Continuous Flow Chemistry

Microreactor exhibits great potential for intensified synthesis of advanced materials and chemicals in continuous flow mode, for its various advantages such as excellent heat and mass transfer efficiency, high controllability, easy scale-up, etc. Among numerous flow patterns, gas-liquid Taylor Flow has been proven as an ideal flow regime to enhance chemical reactions. However, the method to precisely control the Taylor flow pattern is still lacking. 

Motivated by such a challenge, a research team led by Prof. TANG Zhiyong and Associate Prof. ZHANG Jie at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) reported a novel approach of adding pulsation field to precisely regulate the gas-liquid Taylor Flow. Results were published in Chemical Engineering Journal

In this research, the research team used a simple valve arrangement to introduce the pulsation filed, thus producing periodic acceleration and deceleration motion of liquid slugs.

Space-time distribution of gas fraction in bubble formation process (Image by SARI)

By combing visual flow experiments with computational fluid dynamics (CFD) simulation, the temporal-spatial migration of the Taylor flow pattern under pulsating gas intake conditions was investigated. A high-speed camera was used to track the trajectory of gas-liquid interface by the Lagrangian method, while the numerical simulation is used to acquire the flow field distribution at different moments using the Euler method.

Meanwhile, the involved forces during bubble formation and the characteristics of bubble length and velocity under pulsation were analyzed in detail.

(a) Forces versus pulse frequency f at the T-junction, (b) Bubble velocities at downstream (Image by SARI) 

Through studying the temporal-spatial migration of the pattern, the researchers found that the pulsation can increase the power of inertial force on the Taylor flow pattern. Moreover, the pattern can be destroyed when the pulsation energy exceeds a certain value. 

This work provides a new route to regulate precisely the gas-liquid Taylor flow, and will contribute to future applications of this technique to intensify various gas-liquid reactions in continuous flow. 

This work was supported by the Youth Innovation Promotion Association of CAS, the STS Program of CAS and the Frontier Scientific Research Project funded by Shell.  

Featured image: Regulation of Gas-Liquid Taylor Flow by Pulsating Gas Intake in Micro-channel (Image by SARI)


Reference: Yaheng Zhang, Jie Zhang, Zhiyong Tang, Qing Wu, Regulation of gas-liquid Taylor flow by pulsating gas intake in micro-channel, Chemical Engineering Journal, Volume 417, 2021, 129055, ISSN 1385-8947, https://doi.org/10.1016/j.cej.2021.129055. (https://www.sciencedirect.com/science/article/pii/S138589472100646X)


Provided by Chinese Academy of Sciences

Children Less Infectious Than Adults With SARS-COV-2 (Medicine)

Children may not be as infectious in spreading SARS-CoV-2 to others as previously thought, according to new University of Manitoba-led research in CMAJ (Canadian Medical Association Journal).

“Our findings have important public health and clinical implications,” writes principal investigator Dr. Jared Bullard, associate professor, pediatrics/child health and medical microbiology/infectious diseases, Max Rady College of Medicine, University of Manitoba and associate medical director, Cadham Provincial Laboratory in Winnipeg, Manitoba. “If younger children are less capable of transmitting infectious virus, daycare, in-person school and cautious extracurricular activities may be safe to continue, with appropriate precautions in place, and with lower risk to child care staff, educators and support staff than initially anticipated.”

Fourteen researchers from multiple disciplines at the University of Manitoba, Cadham Provincial Laboratory, Manitoba Health and Seniors Care and the Public Health Agency of Canada’s National Microbiology Laboratory analyzed samples from 175 children and 130 adults in Manitoba infected with SARS-CoV-2 to see if there was a difference in infectiousness. Using cell cultures of nasopharyngeal swabs, they investigated viral loads in both groups to determine if children were more infectious.

“As an increasing number of jurisdictions consider whether in-school learning, daycares and extracurricular activities should continue or resume, a better understanding of the relative contributions of children and adolescents to SARS-CoV-2 transmission, when compared with adults, is essential,” the authors write. “This is particularly important given the increased likelihood of asymptomatic infection in this group.”


Reference: Jared Bullard, Duane Funk, Kerry Dust, Lauren Garnett, Kaylie Tran, Alex Bello, James E. Strong, Santina J. Lee, Jillian Waruk, Adam Hedley, David Alexander, Paul Van Caeseele, Carla Loeppky and Guillaume Poliquin, “Infectivity of severe acute respiratory syndrome coronavirus 2 in children compared with adults”, CMAJ April 09, 2021 cmaj.210263; https://www.cmaj.ca/content/early/2021/04/09/cmaj.210263 DOI: https://doi.org/10.1503/cmaj.210263


Provided by CMAJ

New Biosealant Can Stabilize Cartilage, Promote Healing After Injury (Biology)

A new biosealant therapy may help to stabilize injuries that cause cartilage to break down, paving the way for a future fix or – even better – begin working right away with new cells to enhance healing, according to a new animal-based study by researchers at the Perelman School of Medicine at the University of Pennsylvania. Their research was published in Advanced Healthcare Materials.

“Our research shows that using our hyaluronic acid hydrogel system at least temporarily stops cartilage degeneration that commonly occurs after injury and causes pain in joints,” said the study’s senior author, Robert Mauck, PhD, a professor of Orthopaedic Surgery and the director of Penn Medicine’s McKay Orthopaedic Research Laboratory. “In addition to pausing cartilage breakdown, we think that applying this therapy can present a surface that is ‘sticky’ for cells, such as stem cells that are routinely injected into joints to counteract injury. This reinforcing hydrogel could actually synergize with those cells to create a long-term solution.”

Articular cartilage is the tissue that covers the ends of bones at joints. It keeps bones from painfully grinding together, and its density and resilience allow it to undergo a lot of forces amid human movement. Unfortunately, these routine yet complex stresses cause cartilage to wear down easily – particularly amid some form of injury – and is hard to replace or regrow. This means that it is especially important to keep the remaining cartilage strong and stable.

To that end, Mauck, study lead author Jay Patel, PhD, a former post-doctoral fellow in the McKay Lab and now assistant professor at Emory University, and their team developed a therapy to use a modified version of hyaluronic acid – a substance naturally produced by the body’s connective tissue – that could be introduced to the injured cartilage site. They recognized that this therapy needed to follow a twofold key to preserving cartilage: reinforcement and sealing.

“We often relate this combined approach to treating a damaged deck in your backyard,” Patel said. “To fortify the existing wood structure, you need something like a wood hardener, then you can apply a wood sealer to prevent future wear. In the same way, we applied a substance that seeps into the pores of the tissue and provides reinforcement, then ‘sealed’ it by guiding the behavior of injected stem cells towards forming a layer that caps the whole structure.”

In a large animal model, the researchers introduced the biogel to damaged cartilage, showing that it intertwined with the cartilage’s matrix structure to stabilize the cartilage. They also demonstrated that it was retained for at least one week in the joint environment. When living cartilage was tested in the lab, the researchers found that applying the hyaluronic acid biogel restored regular activity to chondrocytes, the cells within cartilage tissue. This meant that the microenvironment around the cells was now being reinforced.

Once reinforced, the researchers shifted to sealing the cartilage, so that further tissue loss at the injury site didn’t erode the cartilage’s structure. To that end, the team combined the hyaluronic acid hydrogel system with an injection of mesenchymal stem/stromal cells, to promote the formation of a thin “living” barrier on the cartilage surface to protect it from further wear. When the researchers compared models that received the treatment to ones that did not, the treatment models displayed a thicker layer of protective tissue that could protect the cartilage’s structure and preserve function.

“We’ve shown that this is an innovative technology and methodology for potentially addressing the complexities of treating damaged cartilage tissue that traditionally have made it so difficult,” said Patel. “Next, we hope to translate this technology to more large animal studies and to the clinic in the near future.”

These findings led to a translational grant from Penn Health Tech, the interdisciplinary center that combines teams from Penn Medicine and Penn Engineering to create new medical technology. Further, the technology is at the heart of a new company (Forsagen LLC) spun out of Penn with support from the Penn Center for Innovation (PCI) Ventures Program, which will attempt to spearhead the system’s entry into the clinic. It is co-founded by both Mauck and Patel, along with study co-author Jason Burdick, a professor of Bioengineering at Penn, and Ana Peredo, a PhD student in Bioengineering.

Funding for this project was provided by Penn Health Tech, the Department of Veterans’ Affairs, the National Science Foundation, and the National Institutes of Health (R01 AR056624, R01 AR077362, CMMI-1548571, IK1 RX003208, IK6 RX003416).

Other co-authors on this study include Claudia Loebel, Kamiel S. Saleh, Brian C. Wise, Edward D. Bonnevie, Liane M. Miller, and James L. Carey.

Editor’s note: Mauck, Patel, and Burdick are equity holders, along with Penn, are equity holders in Forsagen LLC. They also stand to receive financial considerations from future commercialization of the technology.


Reference: Patel, J. M., Loebel, C., Saleh, K. S., Wise, B. C., Bonnevie, E. D., Miller, L. M., Carey, J. L., Burdick, J. A., Mauck, R. L., Stabilization of Damaged Articular Cartilage with Hydrogel‐Mediated Reinforcement and Sealing. Adv. Healthcare Mater. 2021, 2100315. https://doi.org/10.1002/adhm.202100315


Provided by University of Pennsylvania School of Medicine

Researchers Discover Special Binary System (Planetary Science)

Recently, Dr. LI Linjia and Prof. QIAN Shengbang from Yunnan Observatories of the Chinese Academy of Sciences discovered a RR Lyrae star with rapidly decreasing period, AX UMa, and found that AX UMa showed some characteristics different from the normal RR Lyrae stars, indicating that it is a rare binary evolution pulsator. The study was published in The Astronomical Journal.The researchers made multi-band photometric observation on AX UMa by using the 60 cm telescope and Sino-Thai 70 cm telescope located in Yunnan Observatories.By analyzing the light curve data collected from several sky survey observation projects, they obtained the O-C diagram of AX UMa, and calculated that the period change rate is -7.75 days per million years. This value is one or two orders of magnitude higher than the absolute value of the rate of normal RR Lyrae stars.

So far, AX UMa is the field RR Lyrae star which has the fastest decrease in pulsation period, which means that it is rapidly moving to the left in the Hertzsprung-Russell diagram (H-R) diagram.

The researchers found that the color index of AX UMa at minimum light, B-V = 0.295 mag, is smaller than that of normal ab type RR Lyrae (RRab) stars, which indicates that the effective temperature is higher, reaching 7300 K. They believed that AX UMa has a hot subdwarf star, and the system should be a binary evolution pulsator.

Besides, the researchers found that the radial velocities of AX UMa provided by Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) survey varied greatly. The differences in radial velocity indirectly indicated the existence of the companion star.

The rapid decrease of period of AX UMa indicates that it is in the process of rapid evolution towards the left of H-R diagram. This makes it a living sample to study the formation and evolution of horizontal branch stars.


Reference: L.-J. Li, S.-B. Qian et al., “AX UMa, an ab-type RR Lyrae Star with a Rapidly Decreasing Pulsation Period, and Its Binarity”, Astronomical Journal, 161(4), 2021. https://iopscience.iop.org/article/10.3847/1538-3881/abe4df


Provided by Chinese Academy of Sciences

LAMOST Releases Its DR8 Data (Astronomy)

The LAMOST DR8 dataset, including the spectra obtained from the pilot survey through the eighth-year regular survey, was officially released to domestic astronomers and international partners on March 31, according to the National Astronomical Observatories of the Chinese Academy of Sciences.

Scientific users can log on the website at http://www.lamost.org/dr8/ to query and download the DR8 data.

The DR8 dataset includes the spectra obtained from both the low- and medium-resolution survey. A total of 17.23 million spectra were released, which consist of 11.21 million low-resolution spectra from the observation of 5,207 plates, and 1.47 million non-time-domain and 4.55 million time-domain medium-resolution spectra from 1,089 plates. High-quality spectra, with the signal to noise ratio (S/N) over 10, reached the number of 13.28 million.

Fig 1: Left: Footprint of the LAMOST pilot survey and the eight-year regular low-resolution survey. Right: Footprint of the LAMOST medium-resolution commissioning and the first two-year regular medium-resolution survey. (Image by LAMOST team)

Moreover, the stellar spectral parameters of 7.75 million stars were released in DR8, which also include the abundances of 12 elements for part of the stars, such as carbon, magnesium, and calcium. It has been currently the largest stellar spectral parameter catalogue in the world.

It is estimated that by 2022, the number of spectra released by LAMOST will exceed 20 million. Such a huge spectroscopic dataset is the result of the design concept of LAMOST, which is the large-scale spectroscopic sky survey. 

Before LAMOST was built, the number of objects observed by humans had already reached tens of billions, but only one in ten thousand of them had undergone spectroscopic observation. At that time, only a few hundred spectra could be obtained in a single exposure of the largest spectroscopic survey telescope. 

To realize the large-scale spectroscopic sky survey, the designers of LAMOST increased the number of fibers to 4,000, which increased the maximum number of fibers equipped on a telescope by an order of magnitude. In 2008, LAMOST carried out its first light observation, opening a new era of large-scale spectroscopic sky survey.

Moreover, the fast robotic fiber arrangement technology, which was first applied to so large-scale multi-fiber equipment successfully by LAMOST, also plays an important role in the high spectral acquisition rate. To reconfigure for a new sky map only takes 10 minutes, improving the observation efficiency.

“Having operated for 10 years, the huge amount of released data and the increasing study results have manifested the success of LAMOST, for both of its design concept and its technology,” said Prof. ZHAO Yongheng, the Executive Deputy Director of the Center for Operation and Development of LAMOST. 

The spectral data and related products of LAMOST provide valuable insights for studying the structure, origin and evolution of the Milky Way. With the continuous efforts of the LAMOST team and the mining and use of LAMOST data by astronomers all over the world, LAMOST will continue to show more excitement. 

Featured image: LAMOST and the Milky Way. (Image by CHEN Yingwei)


Provided by Chinese Academy of Sciences

An On-off Switch for Gene Editing (Biology)

New, reversible CRISPR method can control gene expression while leaving underlying DNA sequence unchanged

Over the past decade, the CRISPR-Cas9 gene editing system has revolutionized genetic engineering, allowing scientists to make targeted changes to organisms’ DNA. While the system could potentially be useful in treating a variety of diseases, CRISPR-Cas9 editing involves cutting DNA strands, leading to permanent changes to the cell’s genetic material.

Now, in a paper published online in Cell on April 9, researchers describe a new gene editing technology called CRISPRoff that allows researchers to control gene expression with high specificity while leaving the sequence of the DNA unchanged. Designed by Whitehead Institute Member Jonathan Weissman, University of California San Francisco assistant professor Luke Gilbert, Weissman lab postdoc James Nuñez and collaborators, the method is stable enough to be inherited through hundreds of cell divisions, and is also fully reversible.

“The big story here is we now have a simple tool that can silence the vast majority of genes,” says Weissman, who is also a professor of biology at MIT and an investigator with the Howard Hughes Medical Institute. “We can do this for multiple genes at the same time without any DNA damage, with great deal of homogeneity, and in a way that can be reversed. It’s a great tool for controlling gene expression.”

The project was partially funded by a 2017 grant from the Defense Advanced Research Projects Agency to create a reversible gene editor. “Fast forward four years [from the initial grant], and CRISPRoff finally works as envisioned in a science fiction way,” says co-senior author Gilbert. “It’s exciting to see it work so well in practice.”

Genetic engineering 2.0

The classic CRISPR-Cas9 system uses a DNA-cutting protein called Cas9 found in bacterial immune systems. The system can be targeted to specific genes in human cells using a single guide RNA, where the Cas9 proteins create tiny breaks in the DNA strand. Then the cell’s existing repair machinery patches up the holes.

Because these methods alter the underlying DNA sequence, they are permanent. Plus, their reliance on “in-house” cellular repair mechanisms means it is hard to limit the outcome to a single desired change. “As beautiful as CRISPR-Cas9 is, it hands off the repair to natural cellular processes, which are complex and multifaceted,” Weissman says. “It’s very hard to control the outcomes.”

That’s where the researchers saw an opportunity for a different kind of gene editor — one that didn’t alter the DNA sequences themselves, but changed the way they were read in the cell.

This sort of modification is what scientists call “epigenetic” — genes may be silenced or activated based on chemical changes to the DNA strand. Problems with a cell’s epigenetics are responsible for many human diseases such as Fragile X syndrome and various cancers, and can be passed down through generations.

Epigenetic gene silencing often works through methylation — the addition of chemical tags to to certain places in the DNA strand — which causes the DNA to become inaccessible to RNA polymerase, the enzyme which reads the genetic information in the DNA sequence into messenger RNA transcripts, which can ultimately be the blueprints for proteins.

Weissman and collaborators had previously created two other epigenetic editors called CRISPRi and CRISPRa — but both of these came with a caveat. In order for them to work in cells, the cells had to be continually expressing artificial proteins to maintain the changes.

“With this new CRISPRoff technology, you can [express a protein briefly] to write a program that’s remembered and carried out indefinitely by the cell,” says Gilbert. “It changes the game so now you’re basically writing a change that is passed down through cell divisions — in some ways we can learn to create a version 2.0 of CRISPR-Cas9 that is safer and just as effective, and can do all these other things as well.”

Building the switch

To build an epigenetic editor that could mimic natural DNA methylation, the researchers created a tiny protein machine that, guided by small RNAs, can tack methyl groups onto specific spots on the strand. These methylated genes are then “silenced,” or turned off, hence the name CRISPRoff.

Because the method does not alter the sequence of the DNA strand, the researchers can reverse the silencing effect using enzymes that remove methyl groups, a method they called CRISPRon.

As they tested CRISPRoff in different conditions, the researchers discovered a few interesting features of the new system. For one thing, they could target the method to the vast majority of genes in the human genome — and it worked not just for the genes themselves, but also for other regions of DNA that control gene expression but do not code for proteins. “That was a huge shock even for us, because we thought it was only going to be applicable for a subset of genes,” says first author Nuñez.

Also, surprisingly to the researchers, CRISPRoff was even able to silence genes that did not have large methylated regions called CpG islands, which had previously been thought necessary to any DNA methylation mechanism.

“What was thought before this work was that the 30 percent of genes that do not have a CpG island were not controlled by DNA methylation,” Gilbert says. “But our work clearly shows that you don’t require a CpG island to turn genes off by methylation. That, to me, was a major surprise.”

CRISPRoff in research and therapy

To investigate the potential of CRISPRoff for practical applications, the scientists tested the method in induced pluripotent stem cells. These are cells that can turn into countless cell types in the body depending on the cocktail of molecules they are exposed to, and thus are powerful models for studying the development and function of particular cell types.

The researchers chose a gene to silence in the stem cells, and then induced them to turn into nerve cells called neurons. When they looked for the same gene in the neurons, they discovered that it had remained silenced in 90 percent of the cells, revealing that cells retain a memory of epigenetic modifications made by the CRISPRoff system even as they change cell type.

They also selected one gene to use as an example of how CRISPRoff might be applied to therapeutics: the gene that codes for Tau protein, which is implicated in Alzheimer’s disease. After testing the method in neurons, they were able to show that using CRISPRoff could be used to turn Tau expression down, although not entirely off. “What we showed is that this is a viable strategy for silencing Tau and preventing that protein from being expressed,” Weissman says. “The question is, then, how do you deliver this to an adult? And would it really be enough to impact Alzheimer’s? Those are big open questions, especially the latter.”

Even if CRISPRoff does not lead to Alzheimer’s therapies, there are many other conditions it could potentially be applied to. And while delivery to specific tissues remains a challenge for gene editing technologies such as CRISPRoff, “we showed that you can deliver it transiently as a DNA or as an RNA, the same technology that’s the basis of the Moderna and BioNTech coronavirus vaccine,” Weissman says.

Weissman, Gilbert, and collaborators are enthusiastic about the potential of CRISPRoff for research as well. “Since we now can sort of silence any part of the genome that we want, it’s a great tool for exploring the function of the genome,” Weissman says.

Plus, having a reliable system to alter a cell’s epigenetics could help researchers learn the mechanisms by which epigenetic modifications are passed down through cell divisions. “I think our tool really allows us to begin to study the mechanism of heritability, especially epigenetic heritability, which is a huge question in the biomedical sciences,” Nuñez says.

Featured image: A new CRISPR method allows researchers to silence most genes in the human genome without altering the underlying DNA sequence — and then reverse the changes. © Jennifer Cook-Chrysos/Whitehead Institute


Reference: James K. Nuñez, Jin Chen et al., “Genome-wide programmable transcriptional memory by CRISPR-based epigenome editing”, Cell, 2021. DOI: https://doi.org/10.1016/j.cell.2021.03.025


Provided by Whitehead Institute of Biomedical Research

New Machine Learning Method Accurately Predicts Battery State of Health (Engineering)

Electrical batteries are increasingly crucial in a variety of applications, from integration of intermittent energy sources with demand, to unlocking carbon-free power for the transportation sector through electric vehicles (EVs), trains and ships, to a host of advanced electronics and robotic applications.

A key challenge however is that batteries degrade quickly with operating conditions. It is currently difficult to estimate battery health without interrupting the operation of the battery or without going through a lengthy procedure of charge-discharge that requires specialised equipment.

In work recently published by Nature Machine Intelligence, researchers from the Smart Systems Group at Heriot-Watt University in Edinburgh, UK working together with researchers from the CALCE group at the University of Maryland in the US developed a new method to estimate battery health irrespective of operating conditions and battery design or chemistry, by feeding artificial intelligence (AI) algorithms with the raw battery voltage and current operational data.

Darius Roman, the PhD student that designed the AI framework said: “To date, the progress of data-driven models for battery degradation relies on the development of algorithms that carry out inference faster. Whilst researchers often spend a considerable amount of time on model or algorithm development, very few people take the time to understand the engineering context in which the algorithms are applied. By contrast, our work is built from the ground up. We first understand battery degradation through collaborations with the CALCE group at the University of Maryland, where in-house degradation testing of batteries was carried out. We then concentrate on the data, where we engineer features that capture battery degradation, we select the most important features and only then we deploy the AI techniques to estimate battery health.”

In addition, the researchers found that current data-driven models for battery health estimation do not consider model confidence. However, this is often critical for decision making to understand how the AI model came to a certain conclusion and whether the model can be trusted. In their work, the proposed AI model is capable of quantifying uncertainty in its predictions to better support operating decisions.

The developed framework scales up with new chemistries, including the new upcoming solid-state batteries, battery designs and operating conditions and has the potential to unlock new strategies of how batteries can and should be used.

Valentin Robu, from the Smart Systems Group said: “Batteries are increasingly critical to a variety of applications, from robotics to renewable energy integration. A key challenge in these domains is having an accurate, high-confidence estimates of battery state of health. Consider for example, a robotic asset operating in a remote environment such as deep subsea monitoring, where assuring the health of the battery deployed on the robot is mission-critical. Similarly, for energy applications, having an accurate estimate of the remaining useful lifetime of the battery is often critical to a project’s economic viability.”

Funding note:

This research was supported by the EPSRC Centre for Doctoral Training in Embedded Intelligence, the UK Robotics and Artificial Intelligence Hub for Offshore Energy Asset Integrity Management (ORCA Hub) and Responsive Flexibility (ReFlex), one of UK’s largest smart energy demonstration projects, based on the Orkney Islands in the UK.


Reference: Roman, D., Saxena, S., Robu, V. et al. Machine learning pipeline for battery state-of-health estimation. Nat Mach Intell (2021). https://www.nature.com/articles/s42256-021-00312-3 https://doi.org/10.1038/s42256-021-00312-3


Provided by Heriot-Watt University

Interleukin-33 Involved in Immunity to Sars-CoV-2 (Biology)

Freiburg researchers dissect Covid-19 immunity of recovered patients

Early in the Corona pandemic, a team of immunologists from the Max Planck Institute of Immunobiology and Epigenetics in Freiburg and physicians from the University of Freiburg Medical Center joined forces to learn more about immunity in people recovering from Corona infections. The study revealed a yet unknown involvement of Interleukin 33, an important alarm-signal, when immune cells get exposed to Sars-CoV-2 for a second time.

Since the beginning of the coronavirus pandemic, scientists and physicians worldwide undertook enormous efforts to understand the disease caused by the virus. In their latest collaborative study, researchers from the Max Planck Institute of Immunobiology and Epigenetics in Freiburg and physicians from the University of Freiburg Medical Center unveil a novel feature of COVID-19 immunity, which could have implications for future therapies. The study points to the involvement of Interleukin 33, an important danger signal, when immune cells encounter Sars-CoV-2 for a second time. 

“We started the study at a very early stage of the pandemic in 2020 when not much was known about the immune response post-infection”, says Erika Pearce, group leader at the Max Planck Institute of Immunobiology and Epigenetics. “Our aim was to examine the development of immunity in people recovering from Covid-19.” 

Antibodies stick around

An infection with Sars-CoV-2 triggers a complex immune response necessary for the development of immunity to the virus. In simple terms, two linked branches of our immune system need to remember the virus to prevent reinfection, namely antibody-producing B cells and memory T cells. Understanding how this happens in Sars-CoV-2 infection is key for controlling the Covid-19 pandemic and critical for the success of the vaccination efforts.  

For the study, the team examined blood samples of 155 individuals who mostly had mild disease. They measured the amount of antibodies against the SARS-CoV-2 spike protein and found that patients maintain high levels of antibodies more than two months after infection, indicating that they will likely be protected from re-infection. “We thought this was very encouraging, but we also wanted to understand better how the immune system would react to a second encounter with the virus,” says Petya Apostolova, physician and researcher in the lab of Erika Pearce. 

When the virus hits the second time

Effective immunity to a virus is reached when sufficient antibodies and memory T cells are present in the blood of a person who has recovered from the disease or has been vaccinated. To test how this happens after Covid-19, the team exposed blood cells from participants who had antibodies against Sars-CoV-2 to a portion of the virus. They observed that memory T cells had developed and quickly responded to viral proteins. “We measured a broad panel of molecules that our immune cells use to communicate with each other. It was most fascinating to us that of all these measurements, the amount of Interleukin 33 was the closest match to the amount of antibodies people had, and to the activation of their memory T cells,” explains Apostolova. Interleukin 33 (IL-33) is released by cells that sense danger in their environment and has been previously linked to chronic lung disease. IL-33 can have beneficial effects by activating T cells and inducing antibody production, but it can also promote inflammation of the lung. For the first time, this study has linked IL-33 production to immunity to Sars-CoV-2.  

“We believe that Interleukin 33, which is normally produced as an alarm-signal, could be an important link between protection and disease severity,” says Cornelius Waller from the University of Freiburg Medical Center. Indeed, by analyzing public data of lung cells taken from patients during Sars-CoV-2 infection, the researchers were able to show that Interleukin 33 was produced in their lungs. However, identifying the implications of these findings also in the context of lung tissue damage after severe Covid-19 infections will require more investigation.

The group of researchers hopes this collaboration will continue. As Waller pointed out, “we were able to discover this much so quickly through this fantastic synergy between clinicians experienced in the care for Covid-19 patients and experts in the immunology field.” The researchers hope that this study might pave the way to better understanding immunity to Sars-CoV-2 and other viral infections.

Featured image: White blood cells play an important role in the defense against pathogens. © MPI f. Developmental Biology/ Jürgen Berger


Reference: Stanczak, M.A., Sanin, D.E., Apostolova, P. et al. IL-33 expression in response to SARS-CoV-2 correlates with seropositivity in COVID-19 convalescent individuals. Nat Commun 12, 2133 (2021). https://www.nature.com/articles/s41467-021-22449-w https://doi.org/10.1038/s41467-021-22449-w


Provided by Max Planck Gesellschaft

Amounts Of Organic Molecules in Planetary Systems Differ From Early On (Planetary Science)

An international group of scientists led by the RIKEN Cluster for Pioneering Research have studied the chemical composition of 50 protoplanetary-disk forming regions in the Perseus Molecular Cloud, and found that despite being in the same cloud, the amounts of complex organic molecules they contain are quite different. Interestingly, the chemically rich young disks have similar compositions of organic molecules. These findings raise an important question: do solar-like systems share a common chemistry at birth?

It was once believed that complex organic molecules were rare in the universe, and that this rarity might be a reason we have not found evidence of life outside the earth. However, in the last two decades it has become clear that these molecules are common. According to Yao-Lun Yang, who led the research as a member of the Star and Planet Formation Laboratory in the RIKEN Cluster for Pioneering Research, and is now at the University of Virginia as a VICO Origins postdoctoral fellow, “Today, scientists have begun to systematically survey protoplanetary disks–disks where planets eventually form around a star–in the hope of determining how these molecules form, how common they are, and what impact they have on planetary systems.”

Though scientists have looked at individual systems, there is little comparative data to understand these young stars as a group. The RIKEN-led group decided to use observations from the ALMA observatory in Chile, which thanks to its high resolution allows scientists to study chemical compounds in protoplanetary disks. The observations required more than three years to complete.

The group surveyed the emission from organic molecules at specific frequencies in very young disks. They looked at methanol and acetonitrile, as well as two larger molecules, methyl formate and dimethyl ether. They found that different regions had large variation in the abundance of methanol and acetonitrile, though intriguingly, the relative abundance between the two species was remarkably similar. According to Yang, “This implies that there is a common production mechanism of these two molecules, and this give us important hints on how they form in space.” In addition, the abundances of methyl formate and dimethyl ether tended to be higher relative to methanol in denser regions, hinting that there is something about the denser conditions that allows them to be abundant. Their findings were published by the American Astronomical Society last week in The Astrophysical Journal.

According to Nami Sakai, leader of the Star and Planet Formation Laboratory, “This raises important questions regarding how special the chemical environment of the infant Solar system is. We will be able to answer this question in the future by examining the chemical evolution of the gas surrounding young protostars. We hope that such knowledge will be a base for understanding the origin of life on the Earth.

Featured image: An artist’s concept of a planetary system © wiki


Reference: Nami Sakai, Yao-Lun Yang et al., “The Perseus ALMA Chemistry Survey (PEACHES). I. The Complex Organic Molecules in Perseus Embedded Protostars”, Astrophysical Journal, Volume 910, Number 1, 2021. https://iopscience.iop.org/article/10.3847/1538-4357/abdfd6


Provided by Riken