Astronomers Studied An Extremely Low-metallicity Dwarf Compact Star-forming Galaxy: J2229+2725 (Astronomy)

Using the Large Binocular Telescope (LBT)/Multi-Object Dual Spectrograph (MODS), Izotov and colleagues in their recent paper, have obtained optical spectroscopy of one of the most metal-poor dwarf star-forming galaxies (SFG) in the local Universe, J2229+2725. Their study recently appeared on Journal Monthly Notices of the Royal Astronomical Society.

This galaxy with a redshift z = 0.0762 was selected from the Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS). This local SFG possesses extraordinary properties (in particular a very low metallicity and an extremely high O32 ratio), which makes it stand apart from other galaxies. They derived these properties of galaxy from the LBT observations which are most extreme among SFGs in several ways. LBT observations have been supplemented by medium-resolution spectroscopy with the Dual Imaging Spectrograph (DIS) mounted on the 3.5 meter telescope of the Apache Point Observatory (APO).

They also found that its (galaxy) oxygen abundance 12 + logO/H = 7.085±0.031 is among the lowest ever observed for a SFG. With its very low metallicity, an absolute magnitude Mg = −16.39 mag, a low stellar mass M⋆ = 9.1×106 M and a very low mass-to-light ratio M⋆/Lg ∼ 0.0166 (in solar units), J2229+2725 deviates strongly from the luminosity-metallicity relation defined by the bulk of the SFGs in the SDSS.

In addition they found that, J2229+2725 has a very high specific star-formation rate sSFR ∼ 75 Gyr¯1, indicating very active ongoing star formation. Moreover, they also found three other features of J2229+2725 which are most striking, being the most extreme among lowest-metallicity SFGs: (1) a ratio O32 = I([O iii]λ5007)/I([O ii]λ3727) ∼ 53, (2) an equivalent width of the Hβ emission line EW(Hβ) of 577 Å, and (3) an electron number density of ∼ 1000 cm¯3. These properties imply that the starburst in J2229+2725 is very young.

Figure 1. The a) (log R23) – (12 + logO/H), b) log(R23 – a0O32) – (12 + logO/H), and c) log(R23 – a1O32) – (12 + logO/H) relations, where a0 = 0.080 and a1 = 0.080 – 0.00078O32. In all these relations 12 + logO/H is derived by the direct method, R23 = ([O iii]λ4959+λ5007 + [O ii]λ3727)/Hβ and O32 = [O iii]λ5007/[O ii]λ3727. The galaxy J2229+2725 is shown by a red filled star, while J1631+4426 is represented by a blue filled square. Other lowest-metallicity SFGs, the galaxy Little Cub, the galaxy J1234+3901 and the H ii region DDO 68#7 are shown by filled circles. SFGs with the highest O32 ratios in the range ∼ 20 – 40 are shown by asterisks. Samples of SFGs used for the He abundance determination are shown by open circles. Grey dots represent SFGs at z > 0.02 from the SDSS, with the [O iii]λ4363 emission line measured with an accuracy better than 20 per cent. The solid lines in b) and c) are linear fits to the data with log(R23 – a0O32) ≤ 7 and log(R23 – a1O32) ≤ 7, respectively, and excluding J1631+4426. © Izotov et al.

Using the extremely high O32 in J2229+2725, they have also improved the strong-line calibration for the determination of oxygen abundances in the most metal-deficient galaxies, in the range 12 + logO/H < 7.3.

According to authors, the proposed strong-line method can be used to search for SFGs at the extreme end of oxygen abundances 12 + logO/H < 7.0, where other methods, including the direct Te method, cannot be applied because of the weakness of emission lines. This method can also be applied to verify oxygen abundances derived by the direct Te method.

In particular, using our new calibration of the strong-line method, we find that the oxygen abundance for the galaxy J1631+4426 is 0.28 dex higher than the value 12 + logO/H = 6.90±0.03 derived by Kojima et al. using the direct Te method, but it is consistent with their value derived using the strong-line method.

— told Izotov, first author of the study

Featured image: 12 arcsec × 12 arcsec region with the color composite SDSS image of J2229+2725. The 2 arcsec SDSS spectroscopic aperture and 1.2 arcsec wide LBT/MODS slit are indicated by a white circle and yellow parallel lines, respectively. © Izotov et al.


Reference: Y I Izotov, T X Thuan, N G Guseva, J2229+2725: an extremely low-metallicity dwarf compact star-forming galaxy with an exceptionally high [O III]λ5007/[O II]λ3727 flux ratio of 53, Monthly Notices of the Royal Astronomical Society, 2021;, stab1099, https://doi.org/10.1093/mnras/stab1099


Note for editors of other websites: Copyright of this article (editing) totally belongs to our author S. Aman. One is allowed to reuse it only by giving proper credit either to him or to us

‘Information Theory’ Recruited to Help Scientists Find Cancer Genes (Medicine)

Field of mathematics devoted to how information is measured, stored and transmitted uncovers possible key gene that spurs common childhood leukemia

Using a widely known field of mathematics designed mainly to study how digital and other forms of information are measured, stored and shared, scientists at Johns Hopkins Medicine and Johns Hopkins Kimmel Cancer Center say they have uncovered a likely key genetic culprit in the development of acute lymphoblastic leukemia (ALL).

ALL is the most common form of childhood leukemia, striking an estimated 3,000 children and teens each year in the United States alone.

Specifically, the Johns Hopkins team used “information theory,” applying an analysis that relies on strings of zeros and ones — the binary system of symbols common to computer languages and codes — to identify variables or outcomes of a particular process. In the case of human cancer biology, the scientists focused on a chemical process in cells called DNA methylation, in which certain chemical groups attach to areas of genes that guide genes’ on/off switches.

“This study demonstrates how a mathematical language of cancer can help us understand how cells are supposed to behave and how alterations in that behavior affect our health,” says Andrew Feinberg, M.D., M.P.H., Bloomberg Distinguished Professor at the Johns Hopkins University School of Medicine, Whiting School of Engineering and Bloomberg School of Public Health. A founder of the field of cancer epigenetics, Feinberg discovered altered DNA methylation in cancer in the 1980s.

Feinberg and his team say that using information theory to find cancer driver genes may be applicable to a wide variety of cancers and other diseases.

Methylation is now recognized as one way DNA can be altered without changing a cell’s genetic code. When methylation goes awry in such epigenetic phenomena, certain genes are abnormally turned on or off, triggering uncontrolled cell growth, or cancer.

“Most people are familiar with genetic changes to DNA, namely mutations that change the DNA sequence. Those mutations are like the words that make up a sentence, and methylation is like punctuation in a sentence, providing pauses and stops as we read,” says Feinberg. In a search for a new and more efficient way to read and understand the epigenetic code altered by DNA methylation, he worked with John Goutsias, Ph.D., professor in the Department of Electrical and Computer Engineering at The Johns Hopkins University and Michael Koldobskiy, M.D., Ph.D., pediatric oncologist and assistant professor of oncology at the Johns Hopkins Kimmel Cancer Center.

“We wanted to use this information to identify genes that drive the development of cancer even though their genetic code isn’t mutated,” says Koldobskiy.

Results of the study’s findings, led by Feinberg, Koldobskiy and Goutsias, were published April 15 in Nature Biomedical Engineering.

Koldobskiy explains that methylation at a particular gene location is binary — methylation or no methylation — and a system of zeros and ones can represent these differences just as they are used to represent computer codes and instructions.

For the study, the Johns Hopkins team analyzed DNA extracted from bone marrow samples of 31 children newly diagnosed with ALL at The Johns Hopkins Hospital and Texas Children’s Hospital. They sequenced the DNA to determine which genes, across the entire genome, were methylated and which were not.

Newly diagnosed leukemia patients have billions of leukemia cells in their body, says Koldobskiy.

By assigning zeros and ones to pieces of genetic code that were methylated or unmethylated and using concepts of information theory and computer programs to recognize patterns of methylation, the scientists were able to find regions of the genome that were consistently methylated in patients with leukemia and those without cancer.

They also saw genome regions in the leukemia cells that were more randomly methylated, compared with the normal genome, a signal to scientists that those spots may be specifically linked to leukemia cells compared with normal ones.

One gene, called UHRF1, stood out among other gene regions in leukemia cells that had differences in DNA methylation compared with the normal genome.

“It was a big surprise to find this gene, as its link to prostate and other cancer has been suggested but never identified as a driver of leukemia,” says Feinberg.

In normal cells, the protein products of the UHRF1 gene create a biochemical bridge between DNA methylation and DNA packaging, but scientists have not deciphered precisely how alteration of the gene contributes to cancer.

Experiments by the Johns Hopkins team show that laboratory-grown leukemia cells lacking activity of the UHRF1 gene cannot self-renew and perpetuate additional leukemia cells.

“Leukemia cells aim to survive, and the best way to ensure survival is to vary the epigenetics in many genome regions so that no matter what tries to kill the cancer, at least some will survive,” says Koldobskiy.

ALL is the most common pediatric cancer, and Koldobskiy says that decades of research on various treatments and the sequence of those treatments have helped clinicians cure most of these leukemias, but relapsed disease remains a leading cause of death from cancer in children.

“This new approach can lead to more rational ways of targeting the alterations that drive this and likely many other forms of cancer,” says Koldobskiy.

The Johns Hopkins team plans to use information theory to analyze methylation patterns in other cancers. They also plan to determine whether epigenetic alterations in URFH1 are linked to treatment resistance and disease progression in patients with childhood leukemia.

The new research was funded by the National Institutes of Health’s National Cancer Institute (R01CA65438), the National Institute of Diabetes and Digestive and Kidney Diseases (DP1 DK119129), the National Human Genome Research Institute (R01 HG006282), National Science Foundation (1656201), St. Baldrick’s Foundation Fellowship, Unravel Pediatric Cancer and the Damon Runyon Cancer Research Foundation.

In addition to Feinberg, Koldobskiy and Goutsias, contributors to the research include Garrett Jenkinson, Jordi Abante, Varenka Rodriguez DiBlasi, Weiqiang Zhou, Elisabet Pujadas, Adrian Idrizi, Rakel Tryggvadottir, Colin Callahan, Challice Bonifant, Patrick Brown and Hongkai Ji from Johns Hopkins, and Karen R. Rabin from Baylor College of Medicine.

Featured image: An illustration of the research concept that DNA methylation code can be analyzed using information theory, represented by strings of 0s and 1s. This analysis helps researchers understand the epigenetic landscape of cancer (pictured in blue) and identify genes that regulate this landscape, (noted as strings and posts underneath the blue landscape). Credit: Kate Zvorykina (Ella Maru Studio), Design: Michael Koldobskiy and Andrew Feinberg, Johns Hopkins Medicine


Reference: Koldobskiy, M.A., Jenkinson, G., Abante, J. et al. Converging genetic and epigenetic drivers of paediatric acute lymphoblastic leukaemia identified by an information-theoretic analysis. Nat Biomed Eng 5, 360–376 (2021). https://doi.org/10.1038/s41551-021-00703-2


Provided by Johns Hopkins Medicine

Inhibition of the Meprin β Enzyme Linked to the Development of Alzheimer’s Disease Analyzed (Biology)

Findings of researchers at Mainz University could lead to the creation of new drugs

Researchers at Johannes Gutenberg University Mainz (JGU) and the Institute of Molecular Biology of Barcelona have discovered how the blood plasma protein fetuin-B binds to the enzyme meprin β and used a computer model to visualize their findings. These results could lead to the development of new drugs to treat serious diseases such as Alzheimer’s and cancer. Meprin β releases proteins from cell membranes, thus controlling important physiological functions in the human body. However, a dysregulation of this process can trigger the development of Alzheimer’s and cancer. Meprin β is regulated by fetuin-B binding to the enzyme when required, thereby preventing the release of other proteins. Presenting their findings in the journal Proceedings of the National Academy of Sciences (PNAS), the researchers are now the first to describe this binding in detail.

The team at Mainz University produced both meprin β and fetuin-B in insect cells and then allowed them to react with one other in a test tube. By means of measurement of enzyme kinetics and biophysical analyses, the researchers determined that this reaction resulted in an exceptionally stable, high-molecular-mass complex. Their colleagues in Barcelona subsequently managed to crystallize the complex and determine its three-dimensional structure using X-ray crystallography. This involved X-rays being fired at the protein crystals, which allowed the atomic structure of the crystals to be calculated from the diffraction of the X-rays. A computer model of the structure was then generated. “Thanks to the model, we can now see exactly how meprin β and fetuin-B bind together,” said Professor Walter Stöcker, who conducted the research at JGU together with Dr. Hagen Körschgen and Nele von Wiegen. “This research represents an excellent starting point for gaining a better understanding of diseases such as Alzheimer’s and for developing the drugs to combat them.” Meprin β is already known to be involved in the formation of so-called beta-amyloid plaques, which are a characteristic feature of the condition. Moreover, people with Alzheimer’s disease have relatively little fetuin-B in their blood, which in turn may lead to a lack of regulation of meprin β. “If it is possible to develop a drug that binds to the enzyme and inhibits it in a similar way to fetuin-B, this could be a new way of treating Alzheimer’s,” concluded Stöcker.

Featured image: Model of the molecular complex that results when the blood plasma protein fetuin-B (purple and pink) binds with the enzyme meprin β (other colors) © Walter Stöcker


Publication
U. Eckhard et al., The crystal structure of a 250-kDa heterotetrameric particle explains inhibition of sheddase meprin β by endogenous fetuin-B, PNAS 118: 14, 6 April 2021,
DOI:10.1073/pnas.2023839118


Provided by Johannesburg Guntenberg Universitat

Boosting Fiber Optics Communications With Advanced Quantum- enhanced Receiver (Engineering)

Technology could avert capacity crunch by enhancing bandwidth while reducing energy consumption

Fiber optic technology is the holy grail of high-speed, long-distance telecommunications. Still, with the continuing exponential growth of internet traffic, researchers are warning of a capacity crunch.

In AVS Quantum Science, by AIP Publishing, researchers from the National Institute of Standards and Technology and the University of Maryland show how quantum-enhanced receivers could play a critical role in addressing this challenge.

The scientists developed a method to enhance receivers based on quantum physics properties to dramatically increase network performance while significantly reducing the error bit rate (EBR) and energy consumption.

Fiber optic technology relies on receivers to detect optical signals and convert them into electrical signals. The conventional detection process, largely as a result of random light fluctuations, produces “shot noise,” which decreases detection ability and increases EBR.

To accommodate this problem, signals must continually be amplified as pulsating light becomes weaker along the optic cable, but there is a limit to maintaining adequate amplification when signals become barely perceptible.

Quantum-enhanced receivers that process up to two bits of classical information and can overcome the shot noise have been demonstrated to improve detection accuracy in laboratory environments. In these and other quantum receivers, a separate reference beam with a single-photon detection feedback is used so the reference pulse eventually cancels out the input signal to eliminate the shot noise.

The researchers’ enhanced receiver, however, can decode as many as four bits per pulse, because it does a better job in distinguishing among different input states.

To accomplish more efficient detection, they developed a modulation method and implemented a feedback algorithm that takes advantage of the exact times of single photon detection. Still, no single measurement is perfect, but the new “holistically” designed communication system yields increasingly more accurate results on average.

“We studied the theory of communications and the experimental techniques of quantum receivers to come up with a practical telecommunication protocol that takes maximal advantage of the quantum measurement,” author Sergey Polyakov said. “With our protocol, because we want the input signal to contain as few photons as possible, we maximize the chance that the reference pulse updates to the right state after the very first photon detection, so at the end of the measurement, the EBR is minimized.”

The article “Practical quantum-enhanced receivers for classical communication” is authored by Ivan Burenkov, M.V. Jabir, and Sergey V. Polyakov. The article appears in AVS Quantum Science (DOI: 10.1116/5.0036959) and can be accessed at https://aip.scitation.org/doi/10.1116/5.0036959.

Featured image: Illustration showing how single-photon detection is used for feedback. Once correct parameters for the reference beam are established, the input state is extinguished. © Ivan Burenkov


Provided by American Institute of Physics

Astronauts’ Mental Health Risks Tested in the Antarctic (Astronomy)

No Bounce Back for Declines in Positive Emotion

Astronauts who spend extended time in space face stressors such as isolation, confinement, lack of privacy, altered light-dark cycles, monotony and separation from family. Interestingly, so do people who work at international research stations in Antarctica, where the extreme environment is characterized by numerous stressors that mirror those present during long-duration space exploration.  

To better understand the psychological hurdles faced by astronauts, University of Houston professor of psychology Candice Alfano and her team developed the Mental Health Checklist (MHCL), a self-reporting instrument for detecting mental health changes in isolated, confined, extreme (ICE) environments. The team used the MHCL to study psychological changes at two Antarctic stations. The findings are published in Acta Astronautica

“We observed significant changes in psychological functioning, but patterns of change for specific aspects of mental health differed. The most marked alterations were observed for positive emotions such that we saw continuous declines from the start to the end of the mission, without evidence of a ‘bounce-back effect’ as participants were preparing to return home,” reports Alfano. “Previous research both in space and in polar environments has focused almost exclusively on negative emotional states including anxiety and depressive symptoms. But positive emotions such as satisfaction, enthusiasm and awe are essential features for thriving in high-pressure settings.” 

University of Houston professor of psychology Candice Alfano developed the Mental Health Checklist, a self-reporting instrument for detecting mental health changes in isolated, confined, extreme environments. © University of Houston

Negative emotions also increased across the study, but changes were more 
variable and predicted by physical complaints. Collectively, these results might suggest that while changes in negative emotions are shaped by an interaction of individual, interpersonal and situational factors, declines in positive emotions are a more universal experience in ICE environments. “Interventions and counter measures aimed at enhancing positive emotions may, therefore, be critical in reducing psychological risk in extreme settings,” said Alfano. 

At coastal and inland Antarctic stations, Alfano and her team tracked mental health symptoms across a nine-month period, including the harshest winter months, using the MHCL. A monthly assessment battery also examined changes in physical complaints, biomarkers of stress such as cortisol, and the use of different emotion regulation strategies for increasing or decreasing certain emotions. 

Study results also revealed that participants tended to use fewer effective strategies for regulating (i.e., increasing) their positive emotions as their time at the stations increased.  

“Both the use of savoring  purposely noticing, appreciating, and/or intensifying positive experiences and emotions – and reappraisal – changing the way one thinks about a situation – decreased during later mission months compared to baseline. These changes likely help explain observed declines in positive emotions over time,” said Alfano. 

Featured image: NASA astronaut Karen Nyberg watches Earth from the Cupola Observational Module of the International Space Station. Photo courtesy NASA


Provided by University of Houston

Picture Of The Week: In a Cosmic Wonderland (Astronomy)

This panoramic selfie was taken on 9 April 2016 by ESO Photo Ambassador Petr Horálek. Petr was in the Chilean Atacama Desert as a member of ESO’s Fulldome Expedition team, a select group of photographers who captured an array of stunning, ultra-high-definition visuals for use primarily in the ESO Supernova Planetarium & Visitor Centre.

The landscape looms large around photographer Petr in this image, making him appear small beneath the striking Chilean sky. He can be seen standing just beneath a column of zodiacal light — perfect positioning that makes this image appear even more otherworldly.

The wide, round-topped objects visible here are some of the 12-metre antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA is the largest ground-based astronomical observatory in the world, and is located on the Chajnantor Plateau in Chile at an altitude of 5000 metres. A total of 66 antennas make up the array, and can be connected together in different configurations to act as a single telescope, known as an interferometer. This arrangement enables ALMA to be the most powerful explorer of the Universe in millimetre and submillimetre light, the kind of light that is produced by cool, distant, ancient phenomena throughout the cosmos, allowing us to explore the birth of stars, the formation of exoplanets, and distant galaxies

Links

Credit:

ESO/P. Horálek

About the Object


Provided by ESO

Asymmetric Synthesis of Aziridine with a New Catalyst Can Help Develop Novel Medicines (Chemistry)

Unless you’ve studied chemistry in college, it’s unlikely you’ve come across the name aziridine. An organic compound with the molecular formula, C2H4NH, aziridines are well-known among medicinal chemists, who make use of the compound to prepare pharmaceutical drugs such as Mitomycin C, a chemotherapeutic agent known for its anti-tumor activity. Specifically, aziridines are what chemists call “enantiomers”ーmolecules that are mirror images of each other and cannot be superposed on one another. A peculiarity with enantiomers is that the biological activity of one is different from its mirror image and only one of them is desirable for making drugs. Chemists, therefore, regularly opt for “asymmetric” or “enantioselective” synthesis techniques that yield the desired enantiomer in greater amounts.

One such technique that has recently attracted attention from the viewpoint of pharmaceutical synthesis involves the use of oxazolonesーchemical compounds with the molecular formula C3H3NO2ー to prepare aziridines. “Oxazolones are well-known for their versatility in affording biologically active compounds,” explains Professor Shuichi Nakamura from Nagoya Institute of Technology (NITech), Japan, who studies asymmetric reactions, “However, the enantioselective reactions of 2H-azirines with oxazolones have not been very fruitful, despite being touted as one of the most efficient methods to synthesize aziridines.

In a new study recently published in Organic Letters, Prof. Nakamura along with his colleagues from NITech and Osaka University, Japan, explored this issue and, in a significant breakthrough, managed to obtain aziridine-oxazolone compounds in high yields (99%) as well as high enantioselectivity or purity (98%). In addition, the team used an original catalyst they developed to catalyze the reactions they studied.

The team started off by heating α-azideacrylates at 150°C in an organic solvent tetrahydrofuran (THF) to prepare 2H-azirines and then reacted them with oxazolones in presence of various organocatalysts to produce different aziridine-oxazolone compounds. In particular, the team examined the effect of the catalyst cinchonine and various heteroarenecarbonyl and heteroarenesulfonyl groups in organocatalysts derived from cinchona alkaloids and found that reactions using catalysts with either a 2-pyridinesulfonyl group or an 8-quinolinesulfonyl group gave both a high yield (81-99%) as well high enantiopurity (93-98%). In addition, scientists observed that the reaction between a 2H-azirine containing an ethyl ester group and an oxazolone with a 3, 5-dimethoxyphenyl group in presence of the catalyst with 8-quinolinesulfonyl group also gave high yields (98-99%) as well as enantiopurity (97-98%).

The team then moved on to exploring the reaction between 2H-azirine with ethyl ester group and a wider variety of oxazolones in presence of the catalyst with 8-quinolinesulfonyl group. In all of the reactions they observed high yields (77-99%) and enantiopurities (94-99%) except one for the case of an oxazolone bearing a benzyl group and the catalyst with 2-pyridylsulfonyl group that only produced a moderate yield (61%) and purity (86%). Moreover, they were able to convert the obtained aziridines into various other enantiomers without any loss of purity.

Finally, the team proposed a catalytic mechanism and a transition state for the reaction of 2H-azirines with oxazolones in which the catalyst activates both the oxazolone and the 2H-azirine, which then react to give an “addition product” that, in turn, yields the aziridine with regeneration of the catalyst.

While the detailed mechanism is yet to be clarified, scientists are excited by their findings and look forward to the method’s application in medicine and pharmacology. “It has the potential to provide people with new medicines and create new drugs as well as drug candidates that are currently difficult to synthesize. Moreover, the catalyst used in this study can be used for many other stereo-selective synthetic reactions,” observes an optimistic Prof. Nakamura.

Some fascinating consequences to contemplate for sure!

Featured image: Producing aziridines with high yield and high purity using novel catalyst. Scientists from Japan recently proposed a possible transition state for the reaction between aziridines and oxazolones in presence of a cinchona alkaloid sulfonamide catalyst, producing desirable aziridine-oxazolone compounds with high yields and enantioselectivity or purity. Image courtesy: Shuichi Nakamura from NITech


Reference

  • Title of original paper: Enantioselective Reaction of 2H‑Azirines with Oxazol-5-(4H)‑ones Catalyzed by Cinchona Alkaloid Sulfonamide Catalysts
  • Journal: Organic Letters
  • DOI: 10.1021/acs.orglett.1c00259 

Provided by Nagoya Institute of technology

Certain Gut Microbes Make Mosquitoes More Prone to Carry Malaria Parasite (Biology)

Dietary sugars and gut microbes play a key role in promoting malaria parasite infection in mosquitoes. Researchers in China have uncovered evidence that mosquitoes fed a sugar diet show an increased abundance of the bacterial species Asaia bogorensis, which enhances parasite infection by raising the gut pH level. The study appears April 20 in the journal Cell Reports.

“Our work opens a new path for investigations into the role of mosquito-microbiota metabolic interactions concerning their disease-transmitting potential,” says co-senior study author Jingwen Wang of Fudan University in Shanghai, China. “The results may also provide useful insights for the development of preventive strategies for vector control.”

Mosquitoes rely on nectar-derived sugars, such as glucose, for energy, survival, and reproduction. Similarly, glucose is the primary energy source supporting the proliferation of Plasmodium–malaria parasites that are transmitted to human hosts by female mosquitoes of the genus Anopheles. Some indirect evidence also suggests that carbohydrate metabolism influences the capability of mosquitoes to transmit malaria parasites. Although glucose metabolism is expected to play a role in regulating Plasmodium infection in mosquitoes, the underlying mechanisms have not been clear.

To address this question, Wang teamed up with co-senior study author Huiru Tang of Fudan University. They found that feeding Anopheles stephensi mosquitoes a solution containing glucose for five days increased the number of Plasmodium berghei oocytes in the midgut after infection with the parasite. But mosquitoes treated with an antibiotic cocktail did not show this effect, pointing to a critical role for gut microbes in the sugar-induced enhancement of Plasmodium infection.

The sugar diet specifically increased the abundance of A. bogorensis in the mosquito midgut. Infected mosquitoes that were fed glucose and colonized only with A. bogorensis showed an increased number of P. berghei oocytes. Taken together, the findings suggest that sugar intake promotes Plasmodium infection in mosquitoes by increasing the proliferation of A. bogorensis. Additional experiments provided evidence that this bacterial species mediates the sugar-induced enhancement of infection by raising the midgut pH level, which facilitates the sexual development of P. berghei.

“Our study provides crucial molecular insights into how the complex interplay between glucose metabolism of mosquitos and a component of their gut microbiota, A. bogorensis, influences malaria parasite infection,” Tang says. “Targeting mosquito glucose metabolism might be a promising strategy to prevent malaria parasite transmission.”

The study also provides evidence that the specific sugar composition of plant saps might influence malaria transmission by affecting the proliferation of A. bogorensis. Specifically, Parthenium hysterophorus–a plant species that mosquitoes feed on quite frequently–did not promote A. bogorensis proliferation or P. berghei infection when compared with other mosquito-preferred plants. According to the authors, planting this species might reduce malaria transmission. But further studies are needed to investigate the influence of natural plant saps on the microbiota composition of field mosquitoes and to examine the influence of A. bogorensis from field mosquitoes on malaria parasite infection.

The researchers will continue to investigate the metabolic interactions between mosquitos and their microbiota and the influence of these interactions on pathogen transmission. “Our goal is to find out the key metabolites or chemicals that could inhibit malaria parasite infection in mosquitoes,” Wang says.

The authors acknowledge support from the National Institutes of Health, the National Natural Science Foundation of China, and the Research Fund of the State Key Laboratory of Genetic Engineering and the 111 Project from Fudan University.

Cell Reports, Wang, An, and Gao et al.:” Glucose-mediated proliferation of a gut commensal bacterium promotes Plasmodium infection by increasing mosquito midgut pH” https://www.cell.com/cell-reports/fulltext/S2211-1247(21)00306-5


Provided by Cell Press

Forensics Puzzle Cracked via Fluid Mechanical Principles (Forensic Science)

How can clothing of a close-range shooter remain free of bloodstains?

In 2009, music producer Phil Spector was convicted for the 2003 murder of actress Lana Clarkson, who was shot in the face from a very short distance. He was dressed in white clothes, but no bloodstains were found on his clothing — even though significant backward blood spatter occurred.

How could his clothing remain clean if he was the shooter? This real-life forensic puzzle inspired University of Illinois at Chicago and Iowa State University researchers to explore the fluid physics involved.

In Physics of Fluids, from AIP Publishing, the researchers present theoretical results revealing an interaction of the incoming vortex ring of propellant muzzle gases with backward blood spatter.

A detailed analytical theory of such turbulent self-similar vortex rings was given by this group in earlier work and is linked mathematically to the theory of quantum oscillators.

“In our previous work, we determined the physical mechanism of backward spatter as an inevitable instability triggered by acceleration of a denser fluid, blood, toward a lighter fluid, air,” said Alexander Yarin, a distinguished professor at the University of Illinois at Chicago. “This is the so-called Rayleigh-Taylor instability, which is responsible for water dripping from a ceiling.”

Backward spatter droplets fly from the victim toward the shooter after being splashed by a penetrating bullet. So the researchers zeroed in on how these blood droplets interact with a turbulent vortex ring of muzzle gases moving from the shooter toward the victim.

They predict that backward blood spatter droplets can be entrained — incorporated and swept along within its flow — by the approaching turbulent vortex ring, even being turned around.

“This means that such droplets can even land behind the victim, along with the forward splatter being caused by a penetrated bullet,” said Yarin. “With a certain position of the shooter relative to the victim, it is possible for the shooter’s clothing to remain practically free of bloodstains.”

The physical understanding reached in this work will be helpful in forensic analysis of cases such as that of Clarkson’s murder.

“Presumably, many forensic puzzles of this type can be solved based on sound fluid mechanical principles,” said Yarin.

The article “Blood backspatter interaction with propellant gases” is authored by Gen Li, Nathaniel Sliefert, James B. Michael, and Alexander L. Yarin. It will appear in Physics of Fluids on April 20, 2021 (DOI: 10.1063/5.0045214). After that date, it can be accessed at: https://aip.scitation.org/doi/10.1063/5.0045214.

Featured image: Scenarios for the trajectories of droplets at three different inclination angles, where the cases predicted with accounting for the interactions with the vortex ring are shown in red, and those without are shown in blue. © Gen Li, Nathaniel Sliefert, James B. Michael, and Alexander L. Yarin


Reference: Gen Li, Nathaniel Sliefert, James B. Michael, and Alexander L. Yarin , “Blood backspatter interaction with propellant gases” , Physics of Fluids 33, 043318 (2021) https://doi.org/10.1063/5.0045214


Provided by American Institute of Physics