Culture

The authors, Kirill Vasin and Mikhail Eremin, contribute to the theory of electronic and structural properties of FeCr2O4 ferrimagnet. Due to the specific quantum state and the symmetry of FeO4 fragment, it has unusual electric and magnetic properties. Below TOO~150K, it lowers the symmetry with the macroscopic deformations due to the cooperative Jahn-Teller effect. The coupling between macroscopic deformation of the crystal FeCr2O4 and its inner ions shifts was revealed. The team enhanced the microscopic crystal field theory for 3D electrons with Kleiner's correction - the effect of penetrating charges density. It allows to have better prediction of electron-deformation coupling parameters, which is important for magnetostriction applications and critical temperature TOO. A FeO4 fragment has no inversion symmetry, therefore, the magnetization couples to the electric field (magnetoelectric coupling) via a crystal field from the nearest oxygen ions. Experimentally it was discovered by Chinese and German physicists, however, the nature of this effect had been mysterious.

The researchers developed a microscopic theory of magnetoelectric effect involved Fe2+ and Cr3+ spins. They found two effective mechanisms: the single-ion which demands at least a short-range order of Fe spins (spin-liquid or spin-glass, for instance), and the two-ions mechanism, where the canting between Fe and Cr spins is required. Both reproduce the existing experimental data on the electric polarization measurements by the order of the magnitude and the optical absorption spectrum.

Multiferroics are fascinating multifunctional materials which have a wide range of applications in electronics and spintronics, such as actuators, new types of non-volatile energy efficient memory, electric valves driven by magnetic field. etc. Putting this simply, we can magnetize the medium using electric field and vice versa. Magnetoelectric coupling depends on many competing interactions, and the theory is still unclear. The paper provides a method of calculations of the magnetoelectric and electron-deformation coupling parameters for 3D ions. The latter is also used to calculate magnetostriction, which is important for building sensors (like sonars) and actuators.

One of the important consequences is that the magnetic anisotropy can maintain not only the magnetic "memory", but also the electric "memory" of the material. The spin structure must have no inversion symmetry to maintain the electric polarization in the ground state. Also, the interplay of electric and magnetic domains may have a significant impact on electric polarization. To solve these issues, it is necessary to study the magnetic subsystem more accurate as well, which is unclear due to the lack of the experimental data and the complexity of the compound.

In a world first, scientists from the University of Sussex have recorded blood oxygen levels in the hippocampus and provided experimental proof for why the area, commonly referred to as 'the brain's memory centre', is vulnerable to damage and degeneration, a precursor to Alzheimer's disease.

To understand why this region is so sensitive, the University of Sussex researchers, headed up by Dr Catherine Hall from the School of Psychology and Sussex Neuroscience, studied brain activity and blood flow in the hippocampus of mice. The researchers then used simulations to predict that the amount of oxygen supplied to hippocampal neurons furthest from blood vessels is only just enough for the cells to keep working normally.

Dr Catherine Hall, Senior Lecturer in Psychology at the University of Sussex says:

"These findings are an important step in the search for preventative measures and treatments for Alzheimer's, because they suggest that increasing blood flow in the hippocampus might be really effective at preventing damage from happening.

"If it's right that increasing blood flow in the hippocampus is important in protecting the brain from diseases like Alzheimer's, then it will throw further weight behind the importance of regular exercise and a low-cholesterol diet to long-term brain health.

"We think that the hippocampus exists at a watershed. It's just about OK normally, but when anything else happens to decrease brain blood flow, oxygen levels in the hippocampus reduce to levels that stop neurons working. We think that's probably why Alzheimer's disease first causes memory problems - because the early decrease in blood flow stops the hippocampus from working properly.

"The same factors that put you at risk of having a heart attack make you more likely to develop dementia. That's because our brains need enough blood flow to provide energy - in the form of oxygen and glucose - so brain cells can work properly, and because blood flow can clear away waste products such as the beta amyloid proteins that build up in Alzheimer's disease.

"Now we want to discover whether the lower blood flow and oxygen levels in the hippocampus are what causes beta amyloid to start to build up in Alzheimer's disease. Understanding what causes early damage will be really important to help us learn how to treat or prevent disease."

Dr Kira Shaw, a psychology researcher at the University of Sussex who undertook the main experiments, reported:

"We found that blood flow and oxygen levels in the hippocampus were lower than those in the visual cortex. Also, when neurons are active, there is a large increase in blood flow and oxygen levels in the visual cortex. This provides energy to hungry neurons. But in the hippocampus, these responses were much smaller."

The scientists also found that blood vessels in the hippocampus contained fewer mRNA transcripts (codes for making proteins) for proteins that shape blood vessel dilation. Additionally, the cells that dilate small blood vessels, called pericytes, were a different shape in the hippocampus than in the visual cortex.

Dr Shaw concluded: "We think blood vessels in the hippocampus are less able to dilate than in the visual cortex".

The basis for this new take on the classification was laid in 1985, when John Long attributed a fossil tooth plate to a new species, Edaphodon eyrensis. The species was named after Lake Eyre, near which the tooth was found in 1978.

Asscoiate Professor Evgeny Popov had his doubts about the attribution. However, he had to study the fossil personally to advance his theory. The opportunity presented itself during a trip to Australia in 2010. The tooth plate was stored in a museum in Adelaide, South Australia.

"I didn't plan to go there, but I was able to negotiate a temporary transfer of the fossil to Victoria, where I was working with another collection of chimaeroid fossils. The tooth plate was photographed, drawn, measured and studied under a microscope," says Popov.

To further solidify his takeaways, Popov also visited Brisbane, Queensland, where he studied more chimaeroid specimens. As a result, the plate was attributed to Ptyktoptychion Lees, and the species received a new name - Ptyktoptychion eyrensis.

Interestingly, the place of discovery, which is now in the Australian moderate climate, was in polar latitudes during the Aptian age of the Cretaceous (125 to 113 Ma). The changes of polar day and night and frosty weather were not a hindrance for this fish in the shallow waters of prehistoric Australian seas.

Metal-organic framework compounds (MOFs) consist of inorganic and organic groups and are characterised by a large number of pores into which other molecules can be incorporated. MOFs are therefore interesting for many applications, for example for the storage of gases, but also for substance separation, sensor technology or catalysis. Some of these MOF structures react to different guest molecules by changing their structures. They are thus considered switchable.

One of these is "DUT-8", a material that has now been studied at the MX beamlines of BESSY II. "MOF crystals can be analysed very well at the MX beamlines," says HZB expert Dr. Manfred Weiss, who heads the MX team. "MOF crystals have many things in common with protein crystals. For example, both are interspersed with large pores, which are filled with liquid in the protein crystals, while those in MOFs provide space for guest molecules," Weiss explains.

"The diffraction patterns that DUT-8 showed on the HZB-MX beamlines were extremely complex. We were now able to attribute this to various transitions between ordered and less ordered phases," explains Stefan Kaskel. The enclosed guest molecule directs the network into one of over a thousand possible disorder configurations. The results contribute to a better understanding of switching processes and gas exchange reactions in such MOF structures, so that future functional MOF materials can be developed in a targeted manner.

A research group led by Takashi Saito, of the Ehime University Graduate School of Medicine, developed a 2-photon excitation light-sheet fluorescence microscope which (1) lowers phototoxicity, (2) extends the field of view, and (3) heightens spatial resolution. This microscope, when used for the observation of medaka fish, made it possible to observe the whole body of the embryo (an extended field of view) at a cellular level resolution (high spatial resolution) without affecting the growth of the fish (low phototoxicity) over a three-day span of embryonic development. This result was published in the scientific journal Nature Communications (Springer Nature).

1. Background

The fluorescence microscope is widely used in the field of life science to observe molecules inside a cell in a non-invasive way. Light-sheet fluorescence microscopy makes it possible to record three-dimensional images with high acquisition speed and high spatial resolution. However, in conventional light-sheet microscopes, it is difficult to limit photodamage to living tissues, and also difficult to simultaneously achieve wide FOV and high (cell level) spatial resolution.

2. Development of a two-photon excitation wide-field, light-sheet microscope

The Ehime University research group of Takashi Saitou, Sota Takanezawa, and Takeshi Imamura utilized the two-photon excitation phenomenon as a key to solving this problem. The two-photon excitation microscope with infrared lasers enables gentle (low phototoxic) imaging of living organisms. However, because the light must be focused on a narrow range to induce two-photon excitation, the excitation range (in light-sheet microscope, the field of view) is narrow. In order to solve this, we developed simple illumination optics unit with a Bessel beam that expands the laser propagation range in the direction of the optic axis (Fig. 1A). This unit can stretch the beam length to 600-1000 μm while maintaining a 2-3 μm axial resolution when using a 10x magnification NA0.3 objective lens. Using this optical unit, we constructed a two-photon excitation light-sheet microscopy (Fig. 1B), which makes it possible to perform whole-body imaging of medaka larvae with cellular resolution (Fig. 1C).

3. Application to live imaging

The medaka is widely used as a model organism for vertebrate. It is suitable for fluorescent imaging since it is small and transparent. To evaluate the applicability of our microscope for use on living organisms, we performed a phototoxicity assessment. This revealed reduced photodamage compared with the conventional Gaussian beam light-sheet sheet microscope. It is therefore suggested to be suitable for long-term live imaging. We then applied long-term time-lapse imaging of the transgenic medaka in which lymphatic endothelium is labelled with green fluorescent protein, and succeeded in live imaging over three days at intervals of 5 minutes (Fig. 2).

4. Significance of the research

In this study, we developed a new high performance light-sheet fluorescence microscope. Using this technology, we can observe almost all the embryonic growth processes of medaka fish with high cellular resolution over the whole body of the fish. This technology is expected to contribute to the molecular level understanding of embryonic development, the elucidation of pathogenesis for lifestyle-related diseases, and to further the technology of drug development.

CHAPEL HILL, NC - A new study published in Nature Communications demonstrates that a consortium of bacteria designed to complement missing or underrepresented functions in the imbalanced microbiome of inflammatory bowel disease (IBD) patients, prevented and treated chronic immune-mediated colitis in humanized mouse models. The study's senior author, Balfour Sartor, MD, Midget Distinguished Professor of Medicine, Microbiology and Immunology, Co-Director of the UNC Multidisciplinary IBD Center, said the results are encouraging for future use treating Crohn's disease and ulcerative colitis patients.

"The idea with this treatment is to restore the normal function of the protective bacteria in the gut, targeting the source of IBD, instead of treating its symptoms with traditional immunosuppressants that can cause side effects like infections or tumors," Sartor said.

The live bacteria consortia, called GUT-103 and GUT-108, were developed by biotech firm Gusto Global. GUT-103 is comprised of 17 strains of bacteria that work together to protect and feed each other. GUT-108 is a refined version of GUT-103, using 11 human isolates related to the 17 strains. These combinations permit the bacteria to stay in the colon for an extended amount of time, as opposed to other probiotics that are not capable of living in the gut and pass through the system quickly.

GUT-103 and GUT-108 were given orally three times a week to "germ-free" mice (no bacteria present) that had been specially developed and treated with specific human bacteria, creating a humanized mouse model. The therapeutic bacteria consortia worked by addressing upstream targets, rather than targeting a single cytokine to block downstream inflammation responses, and reversed established inflammation.

"It also decreased pathobionts - bacteria that can cause harm - while expanding resident protective bacteria, and produced metabolites promoting mucosal healing and immunoregulatory responses," Sartor said. "Simply put - the treatment increased the good guys and decreased the bad guys."

Because of the robust results seen in this study, and the need for more alternative therapies for Crohn's disease, Sartor would like to see GUT-103 and GUT-108 studied in Phase 1 and 2 clinical trials in the future. He plans to continue his work with Gusto Global to further explore uses of the bacterial consortia.

WHAT:

An environment in which family members support one another and express their feelings can reduce the effects of social deprivation on cognitive ability and development among adopted children, suggests a small study by researchers at the National Institutes of Health. In contrast, rule-driven households where family members are in conflict may increase an adopted child's chances for cognitive, behavioral and emotional difficulties.

The study was conducted by Margaret F. Keil, Ph.D., and colleagues in the Section on Endocrinology and Genetics at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). It appears in Pediatric Research.

Researchers enrolled children who had spent at least eight months in Eastern European orphanages before their adoption by American families. The children ranged from 14 to 40 months of age and were evaluated with physical, psychological and developmental tests twice during the following two years. Families also responded to questionnaires on the children's development and on various aspects of their home lives. The study included 10 adopted children and 19 similar children born to American families.

Overall, the adopted children had significant deficits in growth, cognitive ability and development in comparison to the American-born children. However, differences were smaller among children from families scoring higher in cohesion, where family members provided help and support for each other, and expressiveness--families whose members are encouraged to express their feelings. Children had greater deficits if their families scored higher in conflict--open expression of anger and aggression--and in control--a family life run according to set rules and procedures.

The authors concluded that family cohesion and expressiveness could moderate the effects of pre-adoption adversity, while family conflict and adherence to rules could increase the risk for behavioral problems. The authors added that larger studies are needed to verify their findings.

Hormonal contraceptives, e.g. the pill, the patch, and the vaginal ring, contain synthetic hormones that prevent pregnancy by either stopping ovulation, changing the cervical mucus to stop sperm from passing through the cervix and finding an egg, or changing the womb's lining to prevent a fertilized egg from being implanted in it.

Despite their widespread use, hormonal contraceptives are known to increase the risk of breast cancer, which is the most common cause of cancer-related death among women worldwide, and also topped the list of most commonly diagnosed cancers in 2020.

The main component of hormonal contraceptives are progestins, which, mimic the female sex hormone progesterone. Progesterone is involved in a number of biological processes, including the menstrual cycle, pregnancy, and various aspects of fetal development, like brain programming.

Now, a team of scientists led by Professor Cathrin Brisken at EPFL's School of Life Sciences, have taken a thorough and close look at the different biological effects that different progestins in hormonal contraceptives have on the breast tissue - the mammary epithelium. The work is published in EMBO Molecular Medicine.

"Although we know how different contraceptive formulations affect the cardiovascular system, we know little about their effects on the breast," says Brisken. "So we developed new approaches to compare the most commonly used progestins in different hormonal contraceptives and were surprised to find that some of them stimulate cell proliferation in the breast - while others do not."

The researchers tested the effects of prolonged exposure to different progestins on human breast epithelial cells or HBECs, which line the inner layer of the breast. To do this, they developed "humanized" mouse mammary glands by grafting breast epithelial cells from donated human breast tissue from reduction mammoplasty samples into the animals' milk ducts and monitoring their growth in vivo.

"We found that HBECs engraft and proliferate in mouse milk ducts, maintaining hormone receptor expression and hormone responsiveness, which are crucial factors for establishing a relevant preclinical model and thereby to foster translational research," says Brisken.

The team realized that what distinguished the stimulatory and the innocuous progestins were their "androgenic properties" - a technical term for substances that trigger the development of male characteristics, such as body hair, muscle mass etc. This isn't as strange as it sounds: progesterone, mostly known as a female hormone, is used for the production of the famous male hormone testosterone in both women and men.

Some progestins have androgenic properties, acting like testosterone; some actually block them. The key is a protein known as the androgen receptor, which, when activated by an androgenic progestin, travels into the cell's nucleus where it regulates the expression of certain genes.

Working with the epithelial cells in a mouse model, the researchers found that androgenic progestins act through the androgen receptor to induce the expression of the protein Rankl, which plays an important role in cell proliferation in the mammary epithelium. This effect was not seen with anti-androgenic progestins.

The study showed that androgenic - but not anti-androgenic - progestins promote cell proliferation. "Exposing human breast epithelia to androgenic progestins for prolonged periods of time caused hyperproliferation and changes in the cells that are associated with early, pre-malignant lesions - at least in xenografted human breast epithelia," says De Martino.

"Hormonal contraception exposes women to different progestins with or without estrogen," says Brisken. "The androgenic properties of progestins determine their biological activity in the breast epithelium, and reveal an unexpected role for androgen receptor activity in the proliferation of breast epithelial cells."

The crucial insight of the study is that progestins with anti-androgenic activity may be a safer option with regards to breast cancer risk than testosterone-related compounds, e.g. the widely used contraceptive levonorgestrel ("Plan B"). "It might be possible to prevent breast cancer associated with contraception by making more informed choices taking the molecular composition of a contraceptive into account," concludes Brisken.

East Hanover, NJ. May 28, 2021. An international team of multiple sclerosis (MS) experts has identified four under-researched areas that are critical to advancing symptom management for progressive MS, recommending interdisciplinary collaboration among scientists, clinicians, industry leaders, and those with progressive MS. Their call to action was published in Multiple Sclerosis Journal on March 15, 2021, in the article "Prioritizing progressive MS rehabilitation research: A call from the International Progressive MS Alliance" (doi: 10.1177/1352458521999970). The Alliance was represented by authors from Canada, the United States, the UK, Australia, Denmark, Belgium, Germany, and Switzerland.

Recent advances in MS research have resulted in a variety of disease-modifying therapies that can significantly improve quality of life for people with certain phenotypes of the disease. For example, those with relapsing-remitting MS have access to more than 20 therapies. However, these phenotypes represent only some in the MS community.

A major barrier to the development of rehabilitation therapies for progressive MS is the fact that the vast majority of studies conducted to explore rehabilitative therapies involve people with relapsing-remitting MS, not progressive MS. In addition, trials are often designed based on strategies used for pharmaceutical trials, which are not necessarily conducive to clinical rehabilitation trials. Unfortunately, this lack of clinical data to inform therapies for progressive MS leaves this population with few options to manage potentially debilitating symptoms that can lead to challenges such as loss of a job, personal and family stress, and financial strain.

In this article, experts from research, medicine, and industry highlight four major symptoms affecting people with progressive MS that should be the focus of new research: fatigue, mobility and upper extremity impairment, pain, and cognitive impairment. They contend that rehabilitative therapies show great promise for managing these symptoms and for improving physical and cognitive function as well as quality of life, and that directing research efforts toward rehabilitation is critical to developing effective therapies.

"There is a strong need to study the effect of early preventive interventions and to evaluate management of existing symptoms," says co-author John DeLuca, PhD, Senior Vice President for Research and Training at Kessler Foundation. "Effective symptom management and rehabilitation remain far behind in progressive MS. We have little empirical rehabilitation data, and our understanding of mechanisms underlying symptoms and treatment responses is incomplete." Dr. DeLuca emphasizes, "We have ample evidence from research in other clinical areas that rehabilitation can improve quality of life and find support from diverse payers and stakeholders. Our aim is to bring attention to the pressing need to develop rehabilitation treatment interventions for the progressive MS community."

The drug diABZI -- which activates the body's innate immune response -- was highly effective in preventing severe COVID-19 in mice that were infected with SARS-CoV-2, according to scientists in the Perelman School of Medicine at the University of Pennsylvania. The findings, published this month in Science Immunology, suggest that diABZI could also treat other respiratory coronaviruses.

"Few drugs have been identified as game-changers in blocking SARS-CoV-2 infection. This paper is the first to show that activating an early immune response therapeutically with a single dose is a promising strategy for controlling the virus, including the South African variant B.1.351, which has led to worldwide concern," said senior author Sara Cherry, PhD, a professor of Pathology and Laboratory Medicine and scientific director of the High-Throughput Screening (HTS) Core at Penn Medicine. "The development of effective antivirals is urgently needed for controlling SARS-CoV-2 infection and disease, especially as dangerous variants of the virus continue to emerge."

The SARS-CoV-2 virus initially targets epithelial cells in the respiratory tract. As the first line of defense against infection, the respiratory tract's innate immune system recognizes viral pathogens by detecting their molecular patterns. Cherry and her research team first sought to better understand this effect by observing human lung cell lines under the microscope that had been infected with SARS-CoV-2. They found that the virus is able to hide, delaying the immune system's early recognition and response. The researchers predicted that they may be able to identify drugs -- or small molecules with drug-like properties -- that could set off this immune response in the respiratory cells earlier and prevent severe SARS-CoV-2 infection.

To identify antiviral agonists that would block SARS-CoV-2 infection, the researchers performed high throughput screening of 75 drugs that target sensing pathways in lung cells. They examined their effects on viral infection under microscopy and identified nine candidates --including two cyclic dinucleotides (CDNs) -- that significantly suppressed infection by activating STING (the simulation of interferon genes).

Since CDNs have low potency and make poor drugs, according to Cherry, she and her team decided to also test a newly-developed small molecule STING agonist called diABZI, which is not approved by the Food and Drug Administration but is currently being tested in clinical trials to treat some cancers. The researchers found that diABZI potently inhibits SARS-CoV-2 infection of diverse strains, including variant of concern B.1.351, by stimulating interferon signaling.

Finally, the researchers tested the effectiveness of diABZI in transgenic mice that had been infected with SARS-CoV-2. Because the drug needed to reach the lungs, diABZI was administered through a nasal delivery. diABZI-treated mice showed much less weight loss than the control mice, had significantly-reduced viral loads in their lungs and nostrils, and increased cytokine production -- all supporting the finding that diABZI stimulates interferon for protective immunity.

Cherry said that the study's findings offer promise that diABZI could be an effective treatment for SARS-CoV-2 that could prevent severe COVID-19 symptoms and the spread of infection. Additionally, since diABZI has been shown to inhibit human parainfluenza virus and rhinovirus replication in cultured cells, the STING agonist may be more broadly effective against other respiratory viruses.

"We are now testing this STING agonist against many other viruses," Cherry said. "It's really important to remember that SARS-CoV-2 is not going to be the last coronavirus that we will see and will need protection against."

East Hanover, NJ. May 28, 2021. A team of multiple sclerosis (MS) experts at Kessler Foundation led the first pilot randomized controlled trial of robotic-exoskeleton assisted exercise rehabilitation (REAER) effects on mobility, cognition, and brain connectivity in people with substantial MS-related disability. Their results showed that REAER is likely an effective intervention, and is a promising therapy for improving the lives of those with MS.

The article, "A pilot randomized controlled trial of robotic exoskeleton-assisted exercise rehabilitation in multiple sclerosis," (doi: 10.1016/j.msard.2021.102936) was published on April 4, 2021, by Multiple Sclerosis and Related Disorders. It is available open access at https://www.msard-journal.com/article/S2211-0348(21)00203-0/fulltext.

The authors, are Ghaith J. Androwis, PhD, Brian M. Sandroff, PhD, Peter Niewrzol, MA, Glenn R. Wylie, DPhil, Guang Yue, PhD, and John DeLuca, PhD, of Kessler Foundation, and Farris Fakhoury, DPT, of Kessler Institute for Rehabilitation.

It is common for people with MS to experience impairments in both mobility and cognition, and few therapies exist to manage the range of debilitating symptoms. This lack of treatment options is a major problem for people with MS, especially those with substantial MS-related neurological disability.

Previous research shows that exercise rehabilitation, such as walking, is an effective approach to symptom management, with some research suggesting that even a single exercise rehabilitation intervention can improve both mobility and cognition.

Yet there is a lack of efficacy of exercise rehabilitation on mobility and cognitive outcomes in people with MS who have substantial disability. Adaptive exercise rehabilitation approaches such as body-weight supported treadmill training and robot-assisted gait training have not demonstrated convincing results. Moreover, adaptive interventions lack key interactions between patients and therapists that may improve efficacy.

In this pilot study of 10 participants with significant MS-related neurological disability, researchers explored the use of robotic exoskeletons to manage symptoms. Rehabilitation exercise using robotic exoskeletons is a relatively new approach that enables participants to walk over-ground in a progressive regimen that involves close engagement with a therapist. The Foundation has dedicated a Ekso NR to MS studies to facilitate further research in this area.

As compared to conventional gait training, REAER allows participants to walk at volumes needed to realize functional adaptations--via vigorous neurophysiological demands--that lead to improved cognition and mobility. Effects on brain activity patterns were studied using the functional MRI capabilities of the Rocco Ortenzio Neuroimaging Center at Kessler Foundation.

Investigators compared participants' improvement after four weeks of REAER vs four weeks of conventional gait training, looking at functional mobility, walking endurance, cognitive processing speed, and brain connectivity.

The results were positive: Relative to conventional gait training, four weeks of REAER was associated with large improvements in functional mobility (ηp2=.38), cognitive processing speed (ηp2=.53), and brain connectivity outcomes, most significantly between the thalamus and ventromedial prefrontal cortex (ηp2=.72). "Four weeks is relatively short for an exercise training study," noted Dr. Sandroff, senior research scientist at Kessler Foundation and director of the Exercise Neurorehabilitation Research Laboratory. "Seeing improvements within this timeframe shows the potential for exercise to change how we treat MS. Exercise is really powerful behavior that involves many brain regions and networks that can improve over time and result in improved function."

"This is particularly exciting because therapy using robotic exoskeletons shows such promise for improving the lives of people with co-occurring mobility and cognitive disability, a cohort that likely has the greatest potential to benefit from this new technology," said Dr. Androwis, lead author and research scientist in the Center for Mobility and Rehabilitation Engineering Research at Kessler Foundation. "We're eager to design a larger trial to further study these effects. Based on our initial results, we're optimistic that this approach may be superior to the current standard of care."

Since the onset of the CRISPR genetic editing revolution, scientists have been working to leverage the technology in the development of gene drives that target pathogen-spreading mosquitoes such as Anopheles and Aedes species, which spread malaria, dengue and other life-threatening diseases.

Much less genetic engineering has been devoted to Culex genus mosquitoes, which spread devastating afflictions stemming from West Nile virus--the leading cause of mosquito-borne disease in the continental United States--as well as other viruses such as the Japanese encephalitis virus (JEV) and the pathogen causing avian malaria, a threat to Hawaiian birds.

University of California San Diego scientists have now developed several genetic editing tools that help pave the way to an eventual gene drive designed to stop Culex mosquitoes from spreading disease. Gene drives are designed to spread modified genes, in this case those that disable the ability to transmit pathogens, throughout the targeted wild population.

As detailed in the journal Nature Communications, Xuechun Feng, Valentino Gantz and their colleagues at Harvard Medical School and National Emerging Infectious Diseases Laboratories developed a Cas9/guide-RNA expression "toolkit" designed for Culex mosquitoes. Since such little attention in genetic engineering has been devoted to Culex mosquitoes, the researchers were required to develop their toolkit from scratch, starting with a careful examination of the Culex genome.

"My coauthors and I believe that our work will be impactful for scientists working on the biology of the Culex disease vector since new genetic tools are deeply needed in this field," said Gantz, an assistant research scientist in the Division of Biological Sciences at UC San Diego. "We also believe the scientific community beyond the gene drive field will welcome these findings since they could be of broad interest."

While Culex mosquitoes are less problematic in the United States, they are much more of a health risk in Africa and Asia, where they transmit the worm causing filariasis, a disease that can lead to a chronic debilitating condition known as elephantiasis.

The researchers also demonstrated that their tools could work in other insects.

"These modified gRNAs can increase gene drive performance in the fruit fly and could potentially offer better alternatives for future gene drive and gene-editing products in other species," said Gantz.

Gantz and his colleagues have now tested their new tools to ensure proper genetic expression of the CRISPR components and are now poised to apply them to a gene drive in Culex mosquitoes. Such a gene drive construct could be used to halt pathogen transmission by Culex mosquitoes, or alternatively employed to suppress the mosquito population to prevent biting.

East Hanover, NJ. May 28, 2021. A team of researchers has shown that physical intervention plans that included exoskeleton-assisted walking helped people with spinal cord injury evacuate more efficiently and improved the consistency of their stool. This finding was reported in Journal of Clinical Medicine on March 2, 2021, in the article "The Effect of Exoskeletal-Assisted Walking on Spinal Cord Injury Bowel Function: Results from a Randomized Trial and Comparison to Other Physical Interventions" (doi: 10.3390/jcm10050964).

The authors are Peter H. Gorman, MD, of the University of Maryland School of Medicine, Gail F. Forrest, PhD, of Kessler Foundation's Tim and Caroline Reynolds Center for Spinal Stimulation, Dr. William Scott, of VA Maryland Healthcare System, Pierre K. Asselin, MS, Stephen Kornfeld, MD, Eunkyoung Hong, PhD, and Ann M. Spungen, EdD, of the James J. Peters VA Medical Center.

Bowel dysfunction, a common experience after spinal cord injury, can lead to chronic constipation and incontinence, causing discomfort and frustration. In one survey, more than a third of men with spinal cord injury reported that bowel and bladder dysfunction had the most significant effect on their lives post-injury. Unfortunately, these issues are not easily managed.

Rehabilitation professionals have traditionally managed bowel dysfunction using approaches that target the gastrointestinal system or require manual intervention, but some newer research suggests that physical activity and upright posture may enhance bowel motility. However, few studies have explored the possibility that exoskeletal-assisted walking--in which a person with spinal cord injury wears a robotic suit, enabling them to stand and walk--may be an effective addition to existing intervention plans.

In this study, the research team investigated whether exoskeletal-assisted walking improved bowel function in people with chronic spinal cord injury. They performed a three-center, randomized, controlled, crossover clinical trial in which 50 participants completed 36 sessions of exoskeletal-assisted walking. The researchers evaluated bowel function as a secondary outcome in 49 participants. Bowel function was measured via a 10-question bowel function survey, the Bristol Stool Form Scale, and the Spinal Cord Injury Quality of Life Bowel Management Difficulties instrument.

Results showed that the exoskeletal-assisted walking program provided some improvement in bowel function when compared to a control group. "We saw a notable reduction in bowel evacuation time, with 24 percent of participants reporting an improved experience," said Dr. Forrest, co-author and associate director of the Center for Mobility and Rehabilitation Engineering Research at Kessler Foundation. "We also noted that participants' stools trended toward better consistency, supporting our hypothesis that this intervention may improve several measures of bowel function."

"Our results support the idea that walking, and not just standing, may have a beneficial effect on bowel function," said Dr. Gorman, co-author and chief of the Division of Rehabilitation Medicine at the University of Maryland Rehabilitation and Orthopaedic Institute. "Our goal is to improve the quality of life of those with chronic spinal cord injury, and these encouraging results will help inform future studies on the emerging field of mobility intervention."

Boulder, Colo., USA: The Geological Society of America regularly publishes
articles online ahead of print. For April, GSA Bulletin topics
include multiple articles about the dynamics of China and Tibet; new
insights into the Chicxulub impact structure; and the dynamic topography of
the Cordilleran foreland basin. You can find these articles at

https://bulletin.geoscienceworld.org/content/early/recent

.

Tectonic and eustatic control of Mesaverde Group
(Campanian–Maastrichtian) architecture, Wyoming-Utah-Colorado region,
USA

Keith P. Minor; Ronald J. Steel; Cornel Olariu

Abstract:
We describe and analyze the depositional history and stratigraphic
architecture of the Campanian and Maastrichtian succession of the southern
greater Green River basin of Wyoming, USA, and surrounding areas to better
understand the interplay between tectonic and eustatic drivers that built
the stratigraphy. By integrating new measured sections with published
outcrop, well-log, and paleogeographic data, two new stratigraphic
correlation diagrams, 35 new paleogeographic reconstructions, and six new
tectonic diagrams were created for this part of the Western Interior
Seaway. From this work, two time-scales of organization are evident: (1)
100−300 k.y.-scale, mainly eustatically driven regressive-transgressive
shoreline oscillations that generated repeated sequences of
alluvial-coastal plain-shoreline deposits, passing basinward to subaqueous
deltas, then capped by transgressive estuarine/barrier lagoon deposits, and
(2) 3.0−4.0 m.y.-scale, tectonically driven groups of 10 to 15 of these
eustatically driven units stacked in an offset arrangement to form larger
clastic units, which are herein referred to as clastic wedges. Four
regional clastic wedges are recognized, based on the architectures of these
clastic packages. These are the: (1) Adaville, (2) Rock Springs, (3) Iles,
and (4) Williams Fork clastic wedges. Pre-Mesaverde deposition in the
Wyoming-Utah-Colorado (USA) region during the Middle Cretaceous was
characterized by thickening of the clastic wedge close to the thrust-front,
driven primarily by retroarc foreland basin (flexural) tectonics. However,
a basinward shift in deposition during the Santonian into the early
Campanian (Adaville clastic wedge) signaled a change in the dominant
stratigraphic drivers in the region. Shoreline advance accelerated in the
early to middle Campanian (Rock Springs clastic wedge), as the end of
activity in the thrust belt, growing importance of flat-slab subduction,
and steady eastward migration of the zone of dynamic subsidence led to loss
of the foredeep and forebulge, with the attendant formation of a
low-accommodation shelf environment. This “flat-shelf” environment promoted
large shoreline advances and retreats during sea-level rise and fall.
During the middle to late Campanian (Iles clastic wedge), deep erosion on
the crest of the Moxa Arch, thinning on the crests of the Rock Springs and
Rawlins uplifts, and subsequent Laramide-driven basin formation occurred as
the Laramide blocks began to partition the region. The next clastic package
(Williams Fork clastic wedge) pushed the shoreline over 400 km away from
the thrust belt during the late Campanian. This was followed by a very
large and persistent marine transgression across the region, with the
formation of a Laramide-driven deepwater turbidite basin with toe-of-slope
fans into the early Maastrichtian. The Mesaverde Group in the
Wyoming-Utah-Colorado region is thus characterized by: (1) a succession of
four tectonically driven classic wedges, each comprised of a dozen or so
eustatically driven packages that preserve large basinward and landward
shoreline shifts, (2) broad regional sand and silt dispersal on a
low-accommodation marine shelf setting, (3) a progressive, tectonically
driven, basinward shift of deposition with offset, basinward stacking of
successive clastic wedges, and (4) the gradual formation of various uplifts
and sub-basins, the timing and sizes of which were controlled by the
movement of deep-seated Laramide blocks. The Mesaverde Group in the
Wyoming-Utah-Colorado region provides an outstanding opportunity to study
the dynamic interaction among the tectonic control elements of a subducting
plate (crustal loading-flexure, dynamic subsidence/uplift, and regional
flat-slab basin partitioning), as well as the dynamic interaction of
tectonic and eustatic controls.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B36032.1/598755/Tectonic-and-eustatic-control-of-Mesaverde-Group

A new K-Ar illite dating application to constrain the timing of
subduction in West Sarawak, Borneo

Qi Zhao; Yi Yan; Satoshi Tonai; Naotaka Tomioka; Peter D. Clift ...

Abstract:
The timing of subduction is a fundamental tectonic problem for tectonic
models, yet there are few direct geological proxies for constraining it.
However, the matrix of a tectonic mélange formed in a subduction-accretion
setting archives the physical/chemical attributes at the time of
deformation during the subduction-accretion process. Thus, the deformation
age of the matrix offers the possibility to directly constrain the period
of the subduction-accretion process. Here we date the Lubok Antu tectonic
mélange and the overlying Lupar Formation in West Sarawak, Borneo by K-Ar
analysis of illite. The ages of authigenic illite cluster around 60 Ma and
36 Ma. The maximum temperatures calculated by vitrinite reflectance values
suggest that our dating results were not affected by external heating.
Thus, the ages of authigenic illite represent the deformation age of the
mélange matrix and the timing of the Rajang Unconformity, indicating that
the subduction in Sarawak could have continued until ca. 60 Ma and the
thermal and/or fluid flow events triggered by a major uplift of the Rajang
Group occurred at ca. 36 Ma. Furthermore, this study highlights the
potential of using the tectonic mélange to extract the timeframe of
subduction zone episodic evolution directly.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35895.1/598747/A-new-K-Ar-illite-dating-application-to-constrain

Constraining the effects of dynamic topography on the development of
Late Cretaceous Cordilleran foreland basin, western United States

Zhiyang Li; Jennifer Aschoff

Abstract:
Dynamic topography refers to the vertical deflection (i.e., uplift and
subsidence) of the Earth’s surface generated in response to mantle flow.
Although dynamic subsidence has been increasingly invoked to explain the
subsidence and migration of depocenters in the Late Cretaceous North
American Cordilleran foreland basin (CFB), it remains a challenging task to
discriminate the effects of dynamic mantle processes from other subsidence
mechanisms, and the spatial and temporal scales of dynamic topography is
not well known. To unravel the relationship between sedimentary systems,
accommodation, and subsidence mechanisms of the CFB through time and space,
a high-resolution chronostratigraphic framework was developed for the Upper
Cretaceous strata based on a dense data set integrating >600 well logs
from multiple basins/regions in Wyoming, Utah, Colorado, and New Mexico,
USA. The newly developed stratigraphic framework divides the Upper
Cretaceous strata into four chronostratigraphic packages separated by
chronostratigraphic surfaces that can be correlated regionally and
constrained by ammonite biozones. Regional isopach patterns and shoreline
trends constructed for successive time intervals suggest that dynamic
subsidence influenced accommodation creation in the CFB starting from ca.
85 Ma, and this wave of subsidence increasingly affected the CFB by ca. 80
Ma as subsidence migrated from the southwest to northeast. During 100−75
Ma, the depocenter migrated from central Utah (dominantly flexural
subsidence) to north-central Colorado (dominantly dynamic subsidence).
Subsidence within the CFB during 75−66 Ma was controlled by the combined
effects of flexural subsidence induced by local Laramide uplifts and
dynamic subsidence. Results from this study provide new constraints on the
spatio-temporal footprint and migration of large-scale (>400 km × 400
km) dynamic topography at an average rate ranging from ∼120 to 60 km/m.y.
in the CFB through the Late Cretaceous. The wavelength and location of
dynamic topography (subsidence and uplift) generated in response to the
subduction of the conjugate Shatsky Rise highly varied through both space
and time, probably depending on the evolution of the oceanic plateau (e.g.,
changes in its location, subduction angle and depth, and buoyancy).
Careful, high-resolution reconstruction of regional stratigraphic
frameworks using three-dimensional data sets is critical to constrain the
influence of dynamic topography. The highly transitory effects of dynamic
topography need to be incorporated into future foreland basin models to
better reconstruct and predict the formation of foreland basins that may
have formed under the combined influence of upper crustal flexural loading
and dynamic subcrustal loading associated with large-scale mantle flows.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35838.1/598220/Constraining-the-effects-of-dynamic-topography-on

Mid-Cretaceous thick carbonate accumulation in Northern Lhasa (Tibet):
eustatic vs. tectonic control?

Yiwei Xu; Xiumian Hu; Eduardo Garzanti; Marcelle BouDagher-Fadel; Gaoyuan
Sun ...

Abstract:
Widespread accumulation of thick carbonates is not typical of orogenic
settings. During the mid-Cretaceous, near the Bangong suture in the
northern Lhasa terrane, the shallow-marine carbonates of the Langshan
Formation, reaching a thickness up to ∼1 km, accumulated in an
epicontinental seaway over a modern area of 132 × 103 km 2, about half of the Arabian/Persian Gulf. The origin of
basin-wide carbonate deposits located close to a newly formed orogenic belt
is not well understood, partly because of the scarcity of paleogeographic
studies on the evolution of the northern Lhasa. Based on a detailed
sedimentological and stratigraphic investigation, three stages in the
mid-Cretaceous paleogeographic evolution of northern Lhasa were defined:
(1) remnant clastic sea with deposition of Duoni/Duba formations (Early to
early Late Aptian, ca. 125−116 Ma); (2) expanding carbonate seaway of
Langshan Formation (latest Aptian−earliest Cenomanian, ca. 116−99 Ma); and
(3) closure of the carbonate seaway represented by the Daxiong/Jingzhushan
formations (Early Cenomanian to Turonian, ca. 99−92 Ma). Combined with data
on tectonic subsidence and eustatic curves, we emphasized the largely
eustatic control on the paleogeographic evolution of the northern Lhasa
during the latest Aptian−earliest Cenomanian when the Langshan carbonates
accumulated, modulated by long-term slow tectonic subsidence and high
carbonate productivity.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35930.1/598221/Mid-Cretaceous-thick-carbonate-accumulation-in

Early and middle Miocene ice sheet dynamics in the Ross Sea: Results
from integrated core-log-seismic interpretation

Lara F. Pérez; Laura De Santis; Robert M. McKay; Robert D. Larter; Jeanine
Ash ...

Abstract:
Oscillations in ice sheet extent during early and middle Miocene are
intermittently preserved in the sedimentary record from the Antarctic
continental shelf, with widespread erosion occurring during major ice sheet
advances, and open marine deposition during times of ice sheet retreat.
Data from seismic reflection surveys and drill sites from Deep Sea Drilling
Project Leg 28 and International Ocean Discovery Program Expedition 374,
located across the present-day middle continental shelf of the central Ross
Sea (Antarctica), indicate the presence of expanded early to middle Miocene
sedimentary sections. These include the Miocene climate optimum (MCO ca.
17−14.6 Ma) and the middle Miocene climate transition (MMCT ca. 14.6−13.9
Ma). Here, we correlate drill core records, wireline logs and reflection
seismic data to elucidate the depositional architecture of the continental
shelf and reconstruct the evolution and variability of dynamic ice sheets
in the Ross Sea during the Miocene. Drill-site data are used to constrain
seismic isopach maps that document the evolution of different ice sheets
and ice caps which influenced sedimentary processes in the Ross Sea through
the early to middle Miocene. In the early Miocene, periods of localized
advance of the ice margin are revealed by the formation of thick sediment
wedges prograding into the basins. At this time, morainal bank complexes
are distinguished along the basin margins suggesting sediment supply
derived from marine-terminating glaciers. During the MCO,
biosiliceous-bearing sediments are regionally mapped within the depocenters
of the major sedimentary basin across the Ross Sea, indicative of
widespread open marine deposition with reduced glacimarine influence. At
the MMCT, a distinct erosive surface is interpreted as representing
large-scale marine-based ice sheet advance over most of the Ross Sea
paleo-continental shelf. The regional mapping of the seismic stratigraphic
architecture and its correlation to drilling data indicate a regional
transition through the Miocene from growth of ice caps and inland ice
sheets with marine-terminating margins, to widespread marine-based ice
sheets extending across the outer continental shelf in the Ross Sea.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35814.1/598222/Early-and-middle-Miocene-ice-sheet-dynamics-in-the

Late Quaternary aggradation and incision in the headwaters of the
Yangtze River, eastern Tibetan Plateau, China

Yang Yu; Xianyan Wang; Shuangwen Yi; Xiaodong Miao; Jef Vandenberghe ...

Abstract:
River aggradation or incision at different spatial-temporal scales are
governed by tectonics, climate change, and surface processes which all
adjust the ratio of sediment load to transport capacity of a channel. But
how the river responds to differential tectonic and extreme climate events
in a catchment is still poorly understood. Here, we address this issue by
reconstructing the distribution, ages, and sedimentary process of fluvial
terraces in a tectonically active area and monsoonal environment in the
headwaters of the Yangtze River in the eastern Tibetan Plateau, China.
Field observations, topographic analyses, and optically stimulated
luminescence dating reveal a remarkable fluvial aggradation, followed by
terrace formations at elevations of 55−62 m (T7), 42−46 m (T6), 38 m (T5),
22−36 m (T4), 18 m (T3), 12−16 m (T2), and 2−6 m (T1) above the present
floodplain. Gravelly fluvial accumulation more than 62 m thick has been
dated prior to 24−19 ka. It is regarded as a response to cold climate
during the last glacial maximum. Subsequently, the strong monsoon
precipitation contributed to cycles of rapid incision and lateral erosion,
expressed as cut-in-fill terraces. The correlation of terraces suggests
that specific tectonic activity controls the spatial scale and geomorphic
characteristics of the terraces, while climate fluctuations determine the
valley filling, river incision and terrace formation. Debris and colluvial
sediments are frequently interbedded in fluvial sediment sequences,
illustrating the episodic, short-timescale blocking of the channel ca. 20
ka. This indicates the potential impact of extreme events on geomorphic
evolution in rugged terrain.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35983.1/596999/Late-Quaternary-aggradation-and-incision-in-the

Late Neoproterozoic to early Paleozoic paleogeographic position of the
Yangtze block and the change of tectonic setting in its northwestern
margin: Evidence from detrital zircon U-Pb ages and Hf isotopes of
sedimentary rocks

Bingshuang Zhao; Xiaoping Long; Jin Luo; Yunpeng Dong; Caiyun Lan ...

Abstract:
The crustal evolution of the Yangtze block and its tectonic affinity to
other continents of Rodinia and subsequent Gondwana have not been well
constrained. Here, we present new U-Pb ages and Hf isotopes of detrital
zircons from the late Neoproterozoic to early Paleozoic sedimentary rocks
in the northwestern margin of the Yangtze block to provide critical
constraints on their provenance and tectonic settings. The detrital zircons
of two late Neoproterozoic samples have a small range of ages (0.87−0.67
Ga) with a dominant age peak at 0.73 Ga, which were likely derived from the
Hannan-Micangshan arc in the northwestern margin of the Yangtze block. In
addition, the cumulative distribution curves from the difference between
the depositional age and the crystalline age (CA−DA) together with the
mostly positive εHf(t) values of these zircon crystals
(−6.8 to +10.7, ∼90% zircon grains with εHf[t]
> 0) suggest these samples were deposited in a convergent setting during
the late Neoproterozoic. In contrast, the Cambrian−Silurian sediments share
a similar detrital zircon age spectrum that is dominated by Grenvillian
ages (1.11−0.72 Ga), with minor late Paleoproterozoic (ca. 2.31−1.71 Ga),
Mesoarchean to Neoarchean (3.16−2.69 Ga), and latest Archean to early
Paleoproterozoic (2.57−2.38 Ga) populations, suggesting a significant
change in the sedimentary provenance and tectonic setting from a convergent
setting after the breakup of Rodinia to an extensional setting during the
assembly of Gondwana. However, the presence of abundant Grenvillian and
Neoarchean ages, along with their moderately to highly rounded shapes,
indicates a possible sedimentary provenance from exotic continental
terrane(s). Considering the potential source areas around the Yangtze block
when it was a part of Rodinia or Gondwana, we suggest that the source of
these early Paleozoic sediments had typical Gondwana affinities, such as
the Himalaya, north India, and Tarim, which is also supported by their
stratigraphic similarity, newly published paleomagnetic data, and
tectono-thermal events in the northern fragments of Gondwana. This implies
that after prolonged subduction in the Neoproterozoic, the northwestern
margin of the Yangtze block began to be incorporated into the assembly of
Gondwana and then accept sediments from the northern margin of Gondwanaland
in a passive continental margin setting.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35980.1/597000/Late-Neoproterozoic-to-early-Paleozoic

Constraining the duration of the Tarim flood basalts (northwestern
China): CA-TIMS zircon U-Pb dating of tuffs

Yu-Ting Zhong; Zhen-Yu Luo; Roland Mundil; Xun Wei; Hai-Quan Liu ...

Abstract:
The Early Permian Tarim large igneous province (LIP) in northwestern China
comprises voluminous basaltic lava flows, as well as ultramafic and silicic
intrusions. The age and duration of the Tarim LIP remains unclear, and thus
the rate of magma production and models of potential environmental effects
are uncertain. Here we present high-precision chemical abrasion−isotope
dilution−thermal ionization mass spectrometry zircon U-Pb ages for three
newly discovered tuff layers interlayered with lava flows in the
Kupukuziman and Kaipaizileike formations in the Keping area (Xinjiang,
northwest China). The volcanism of the Kupukuziman Formation is constrained
to a short duration from 289.77 ± 0.95 to 289.41 ± 0.52 Ma. An age for the
overlying Kaipaizileike Formation is 284.27 ± 0.39 Ma, bracketing the
duration of the entire eruptive phase of the Tarim flood basalts at ∼5.5
m.y. The low eruption rate and relatively long duration of magmatism is
consistent with a plume incubation model for the Tarim LIP.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B36053.1/597001/Constraining-the-duration-of-the-Tarim-flood

Late Pleistocene−Holocene flood history, flood-sediment provenance and
human imprints from the upper Indus River catchment, Ladakh Himalaya

Choudhurimayum Pankaj Sharma; Poonam Chahal; Anil Kumar; Saurabh Singhal;
YP Sundriyal ...

Abstract:
The Indus River, originating from Manasarovar Lake in Tibet, runs along the
Indus Tsangpo suture zone in Ladakh which separates the Tethyan Himalaya in
the south from the Karakoram zone to the north. Due to the barriers created
by the Pir-Panjal ranges and the High Himalaya, Ladakh is located in a rain
shadow zone of the Indian summer monsoon (ISM) making it a high-altitude
desert. Occasional catastrophic hydrological events are known to endanger
lives and properties of people residing there. Evidence of such events in
the recent geologic past that are larger in magnitude than modern
occurrences is preserved along the channels. Detailed investigation of
these archives is imperative to expand our knowledge of extreme floods that
rarely occur on the human timescale. Understanding the frequency,
distribution, and forcing mechanisms of past extreme floods of this region
is crucial to examine whether the causal agents are regional, global, or
both on long timescales. We studied the Holocene extreme flood history of
the Upper Indus catchment in Ladakh using slackwater deposits (SWDs)
preserved along the Indus and Zanskar Rivers. SWDs here are composed of
stacks of sand-silt couplets deposited rapidly during large flooding events
in areas where a sharp reduction of flow velocity is caused by local
geomorphic conditions. Each couplet represents a flood, the age of which is
constrained using optically stimulated luminescence for sand and
accelerator mass spectrometry and liquid scintillation counter 14C for charcoal specks from hearths. The study suggests
occurrence of large floods during phases of strengthened ISM when the
monsoon penetrated into arid Ladakh. Comparison with flood records of
rivers draining other regions of the Himalaya and those influenced by the
East Asian summer monsoon (EASM) indicates asynchronicity with the Western
Himalaya that confirms the existing anti-phase relationship of the ISM-EASM
that occurred in the Holocene. Detrital zircon provenance analysis
indicates that sediment transportation along the Zanskar River is more
efficient than the main Indus channel during extreme floods. Post−Last
Glacial Maximum human migration, during warm and wet climatic conditions,
into the arid upper Indus catchment is revealed from hearths found within
the SWDs.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35976.1/597002/Late-Pleistocene-Holocene-flood-history-flood

New insights into the formation and emplacement of impact melt rocks
within the Chicxulub impact structure, following the 2016 IODP-ICDP
Expedition 364

Sietze J. de Graaff; Pim Kaskes; Thomas Déhais; Steven Goderis; Vinciane
Debaille ...

Abstract:
This study presents petrographic and geochemical characterization of 46
pre-impact rocks and 32 impactites containing and/or representing impact
melt rock from the peak ring of the Chicxulub impact structure (Yucatán,
Mexico). The aims were both to investigate the components that potentially
contributed to the impact melt (i.e., the pre-impact lithologies) and to
better elucidate impact melt rock emplacement at Chicxulub. The impactites
presented here are subdivided into two sample groups: the lower impact melt
rock−bearing unit, which intrudes the peak ring at different intervals, and
the upper impact melt rock unit, which overlies the peak ring. The
geochemical characterization of five identified pre-impact lithologies
(i.e., granitoid, dolerite, dacite, felsite, and limestone) was able to
constrain the bulk geochemical composition of both impactite units. These
pre-impact lithologies thus likely represent the main constituent
lithologies that were involved in the formation of impact melt rock. In
general, the composition of both impactite units can be explained by mixing
of the primarily felsic and mafic lithologies, but with varying degrees of
carbonate dilution. It is assumed that the two units were initially part of
the same impact-produced melt, but discrete processes separated them during
crater formation. The lower impact melt rock−bearing unit is interpreted to
represent impact melt rock injected into the crystalline basement during
the compression/excavation stage of cratering. These impact melt rock
layers acted as delamination surfaces within the crystalline basement,
accommodating its displacement during peak ring formation. This movement
strongly comminuted the impact melt rock layers present in the peak ring
structure. The composition of the upper impact melt rock unit was
contingent on the entrainment of carbonate components and is interpreted to
have stayed at the surface during crater development. Its formation was not
finalized until the modification stage, when carbonate material would have
reentered the crater.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35795.1/597003/New-insights-into-the-formation-and-emplacement-of

Isotopic spatial-temporal evolution of magmatic rocks in the Gangdese
belt: Implications for the origin of Miocene post-collisional giant
porphyry deposits in southern Tibet

Chen-Hao Luo; Rui Wang; Roberto F. Weinberg; Zengqian Hou

Abstract:
Crustal growth is commonly associated with porphyry deposit formation
whether in continental arcs or collisional orogens. The Miocene high-K
calc-alkaline granitoids in the Gangdese belt in southern Tibet, associated
with porphyry copper deposits, are derived from the juvenile lower crust
with input from lithospheric mantle trachytic magmas, and are characterized
by adakitic affinity with high-Sr/Y and La/Yb ratios as well as high Mg#
and more evolved isotopic ratios. Researchers have argued, lower crust with
metal fertilization was mainly formed by previous subduction-related
modification. The issue is that the arc is composed of three stages of
magmatism including Jurassic, Cretaceous, and Paleocene−Eocene, with peaks
of activity at 200 Ma, 90 Ma, and ca. 50 Ma, respectively. All three stages
of arc growth are essentially similar in terms of their whole-rock
geochemistry and Sr-Nd-Hf isotopic compositions, making it difficult to
distinguish Miocene magma sources. This study is based on ∼430 bulk-rock
Sr-Nd isotope data and ∼270 zircon Lu-Hf isotope data and >800
whole-rock geochemistry analyses in a 900-km-long section of the Gangdese
belt. We found large scale variations along the length of the arc where the
Nd-Hf isotopic ratios of the Jurassic, Cretaceous, and Paleocene−Eocene arc
rocks change differently from east to west. A significant feature is that
the spatial distribution of Nd-Hf isotopic values of the Paleocene−Eocene
arc magmas and the Miocene granitoids, including metallogenic ones, are
“bell-shaped” from east to west, with a peak of εNd(t) and εHf (t) at ∼91°E. In contrast, the Jurassic and Cretaceous arc
magmas have different isotopic distribution patterns as a function of
longitude. The isotopic spatial similarity of the Paleocene−Eocene and
Miocene suites suggests that the lower crust source of the metallogenic
Miocene magmas is composed dominantly of the Paleocene−Eocene arc rocks.
This is further supported by abundant inherited zircons dominated by
Paleocene−Eocene ages in the Miocene rocks. Another important discovery
from the large data set is that the Miocene magmatic rocks have higher Mg # and more evolved Sr-Nd-Hf isotopic compositions than all
preceding magmatic arcs. These characteristics indicate that the
involvement of another different source was required to form the Miocene
magmatic rocks. Hybridization of the isotopically unevolved primary magmas
with isotopically evolved, lithospheric mantle-derived trachytic magmas is
consistent with the geochemical, xenolith, and seismic evidence and is
essential for the Miocene crustal growth and porphyry deposit formation. We
recognize that the crustal growth in the collisional orogen is a two-step
process, the first is the subduction stage dominated by typical magmatic
arc processes leading to lower crust fertilization, the second is the
collisional stage dominated by partial melting of a subduction-modified
lower crust and mixing with a lithospheric mantle-derived melt at the
source depth.

View article:

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B36018.1/596769/Isotopic-spatial-temporal-evolution-of-magmatic

Oxygen isotope (δ18O) trends measured from Ordovician
conodont apatite using secondary ion mass spectrometry (SIMS):
Implications for paleo-thermometry studies

Cole T. Edwards; Clive M. Jones; Page C. Quinton; David A. Fike

Abstract:
The oxygen isotopic compositions (δ18O) of minimally altered phosphate
minerals and fossils, such as conodont elements, are used as a proxy for
past ocean temperature. Phosphate is thermally stable under low to moderate
burial conditions and is ideal for reconstructing seawater temperatures
because the P-O bonds are highly resistant to isotopic exchange during
diagenesis. Traditional bulk methods used to measure conodont δ18O include
multiple conodont elements, which can reflect different environments and
potentially yield an aggregate δ18O value derived from a mixture of
different water masses. In situ spot analyses of individual elements using
micro-analytical techniques, such as secondary ion mass spectrometry
(SIMS), can address these issues. Here we present 108 new δ18O values using
SIMS from conodont apatite collected from four Lower to Upper Ordovician
stratigraphic successions from North America (Nevada, Oklahoma, and the
Cincinnati Arch region of Kentucky and Indiana, USA). The available
elements measured had a range of thermal alteration regimes that are
categorized based on their conodont alteration index (CAI) as either low
(CAI = 1−2) or high (CAI = 3−4). Though individual spot analyses of the
same element yield δ18O values that vary by several per mil (‰), most form
a normal distribution around a mean value. Isotopic variability of
individual spots can be minimized by avoiding surficial heterogeneities
like cracks, pits, or near the edge of the element and the precision can be
improved with multiple (≥4) spot analyses of the same element. Mean δ18O
values from multiple conodonts from the same bed range between 0.0 and 4.3‰
(median 1.0‰), regardless of low or high CAI values. Oxygen isotopic values
measured using SIMS in this study reproduce values similar to published
trends, namely, δ18O values increase during the Early−Middle Ordovician and
plateau by the mid Darriwilian (late Middle Ordovician). Twenty-two of the
measured conodonts were from ten sampled beds that had been previously
measured using bulk analysis. SIMS-based δ18O values from these samples are
more positive by an average of 1.7‰ compared to bulk values, consistent
with observations by others who attribute the shift to carbonate- and
hydroxyl-related SIMS matrix effects. This offset has implications for
paleo-temperature model estimates, which indicate that a 4 °C temperature
change corresponds to a 1‰ shift in δ18O (‰). Although this uncertainty
precludes precise paleo-temperature reconstructions by SIMS, it is valuable
for identifying spatial and stratigraphic trends in temperature that might
not have been previously possible with bulk approaches.

View article

:
https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35891.1/596655/Oxygen-isotope-18O-trends-measured-from-Ordovician

Viruses are perfect molecular machines. Their only goal is to insert their genetic material into healthy cells and thus multiply. With deadly precision, they thereby can cause diseases that cost millions of lives and keep the world on edge. One example for such a virus, although currently less discussed, is HIV that causes the ongoing global AIDS-epidemic. Despite the progress made in recent years, 690 000 people died in 2019 alone as a result of the virus infection. "If you want to know the enemy, you have to know all its friends," says Martin Obr, postdoc at the Schur group at IST Austria. Together with his colleagues, he therefore studies a virus belonging to the same family as HIV - the Rous sarcoma virus, a virus causing cancer in poultry. With its help, he now gained new insights into the important role a small molecule plays in the assembly of these type of viruses.

Protecting the virus blueprint

In their study, published in the journal Nature Communications, the team together with collaborators at Cornell University and the University of Missouri focused on the late phase of retrovirus replication. "It is a long way from an infected cell to the mature virus particle that can infect another cell," explains first author Martin Obr. A new particle buds from the cell in an immature, non-infectious state. It then forms a protective shell, a so-called capsid, around its genetic information and becomes infectious. This protective shell consists of a protein, which is organized in hexamers and a few pentamers. The team discovered that a small molecule called IP6 plays a major role in stabilizing the protein shell within the Rous sarcoma virus.

"If the protective shell is not stable, the genetic information of the virus could be released prematurely and will be destroyed, but if it's too stable the genome can't exit at all and, therefore, becomes useless," says Assistant Professor Florian Schur. In a previous study, he and his colleagues were able to show IP6 is important in the assembly of HIV. Now, the team proved it to be as important in other retroviruses showing just how essential the small molecule is in the virus life cycle. "When building a car, you have all these big metal parts, like the hood, the roof and the doors - the screws are connecting everything. In our case, the big parts are the capsid proteins and the IP6 molecules are the screws," says Obr.

Unexpected flexibility

Further developing cryo-electron tomography, a technique that allows scientists to look at extremely small samples in their natural state, the team was able to see how variable the shapes formed by capsid proteins are. "Now we ask ourselves: Why does the virus change the shape of its capsid? What is it adapting to?" says postdoc Martin Obr. Different capsid shapes within the same type of virus could point to differences in the infectivity of virus particles. "Whatever happens, happens for a reason but there is no clear answer yet," says Florian Schur. Further developing the technology to get to the bottom of these highly optimized pathogens remains a challenging and fascinating task for the scientists.