Earth

Researchers in Japan have identified the potential genes responsible for coral bleaching caused by temperature elevation.

Researchers carried out a transcriptomic analysis with the symbiotic sea anemone Exaiptasia diaphana (Fig.1), an emerging model cnidarian, under multiple culture conditions. The temperature rise and the shift to a non-symbiotic state (a state in which two organisms are not interdependent on one another) caused the expression levels of 292 genes to alter dramatically and irreversibly (Fig.2). The research group argues that the 292 "Heat Induced Bleaching Associated" (HIBA) genes include factors of coral bleaching as a result of temperature elevation.

Coral reefs are a major reservoir of biodiversity in the sea. Their ecosystem relies on a stable symbiotic relationship between the host cnidarian animals, including corals and sea anemones, and the symbiont dinoflagellate. Ongoing environmental changes due to global warming can permanently damage the symbiosis: a phenomenon known as 'coral bleaching.' However, mechanisms for maintaining stable symbiosis are poorly understood.

In the study, the HIBA genes were subjected to a functional classification analysis and divided into four major functional groups: transporters, oxidation-reduction, lysosomes, and carbohydrate metabolism (Fig. 3). According to Shinchiro Maruyama, an assistant professor at Tohoku University "Lysosome is a versatile organelle that degrades various substances in a cell." He adds that "inhabitance of the symbiont dinoflagellate in an organelle called 'symbiosome,' something that resembles lysosomes, suggests a relationship between lysosomes and bleaching; a situation where number of symbionts has decreased in the host cnidarian animal." In addition, symbiont carbohydrates have long been believed to contribute to symbiosis. Based on these factors, the team hypothesizes that degradation of carbohydrates in lysosomes is the central function of the HIBA genes, and generates the need for further investigation.

Researchers have discovered a biochemical oxygen sensing system conserved across biological kingdoms, which allows both plant and animal cells to sense and respond appropriately to changes in oxygen levels - an ability central to the survival of most forms of life. The newly identified enzymatic oxygen sensor is functionally and biochemically identical in plants and animals. Because oxygen sensing is impaired in many human diseases, like cancer, the findings could pave the way to new therapeutic interventions for addressing cellular hypoxia (oxygen deficiency). In order for cells and tissues to adapt to hypoxic conditions, they must first be able to detect oxygen deficiencies. Previous research has shown that a transcription factor called hypoxia inducible factor (HIF) works as an oxygen sensor in humans. Other molecular hypoxia signaling systems have been identified across all four eukaryotic kingdoms; in plants, for example, plant cysteine oxidase enzymes control responses to hypoxia. Norma Masson and colleagues investigated this type of cysteine oxidation in animals and identified the enzyme cysteamine (2-aminoethanethiol) dioxygenase (ADO), which functions as an oxygen sensor in both animals and plants. Masson et al. suggest that ADO likely operates on a shorter timescale than HIF, producing more rapid responses to hypoxic conditions. Neither ADO nor HIF, however, is mutually exclusive - the results predict that both the ADO and HIF systems will interact to produce responses to hypoxia.

A strain of the common cold virus has been found to potentially target, infect and destroy cancer cells in patients with bladder cancer, a new study in the medical journal Clinical Cancer Research reports. No trace of the cancer was found in one patient following treatment with the virus.

Researchers from the University of Surrey and Royal Surrey County Hospital investigated the safety and tolerability of exposure to the oncolytic ('cancer-killing') virus coxsackievirus (CVA21), a naturally occurring strain of the common cold, in fifteen patients with non-muscle invasive bladder cancer (NMIBC). NMIBC is found in the tissue of the inner surface of the bladder and is the tenth most common cancer in the UK with approximately 10,000 people each year diagnosed with the illness.

Current treatments for this cancer are problematic. Transurethral resection, an invasive procedure that removes all visible lesions, has a high tumour recurrence rate ranging from 50 per cent to 70 per cent as well as a high tumour progression rate between 10 per cent and 20 per cent over a period of two to five years. Another common course of treatment, immunotherapy with Bacille Calmette-Guerin, a live bacterium used to treat bladder cancer, has been found to have serious side effects in one third of NMIBC patients while one third do not respond to the treatment at all.

During this pioneering study fifteen NMIBC patients, one week prior to pre scheduled surgery to remove their tumours, received CVA21 via a catheter in the bladder. Examination of tissue samples post-surgery discovered that the virus was highly selective, targeting only cancerous cells in the organ and leaving all other cells intact. The virus was found to have infected cancerous cells and replicated itself causing the cells to rupture and die. Urine samples taken from patients on alternate days detected 'shedding' from the virus indicating that once virally infected cancer cells had died, the newly replicated virus continued to attack more cancerous cells in the organ.

Typically tumours in the bladder do not have immune cells, preventing a patient's own immune system from eliminating the cancer as it grows. Evidence suggests treatment with CVA21 inflames the tumour causing immune cells to rush into the cancer environment, targeting and killing the cancer cells. These tumours devoid of immune cells are known as 'cold' areas immunologically; however, treatment with the virus causes inflammation and immune cell stimulation to create 'immunological 'heat'. 'Hot' tumours in this way are more likely to be rejected by the immune system.

Following treatment with the virus cell death was identified in the majority of the patients' tumours. In one patient no trace of the cancer was found during surgery.

Hardev Pandha, Principal Investigator of the study and Professor of Medical Oncology at the University of Surrey, said: "Non-muscle invasive bladder cancer is a highly prevalent illness that requires an intrusive and often lengthy treatment plan. Current treatment is ineffective and toxic in a proportion of patients and there is an urgent need for new therapies.

"Coxsackievirus could help revolutionise treatment for this type of cancer. Reduction of tumour burden and increased cancer cell death was observed in all patients and removed all trace of the disease in one patient following just one week of treatment, showing its potential effectiveness. Notably, no significant side effects were observed in any patient."

Dr Nicola Annels, Research Fellow at the University of Surrey, said: "Traditionally viruses have been associated with illness however in the right situation they can improve our overall health and wellbeing by destroying cancerous cells. Oncolytic viruses such as the coxsackievirus could transform the way we treat cancer and could signal a move away from more established treatments such as chemotherapy."

ST. PETERSBURG, Fla. ( July 4, 2019).--Scientists led by the USF College of Marine Science used NASA satellite observations to discover the largest bloom of macroalgae in the world called the Great Atlantic Sargassum Belt (GASB), as reported in Science.

They confirmed that the belt of brown macroalgae called Sargassum forms its shape in response to ocean currents, based on numerical simulations. It can grow so large that it blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico. This happened last year when more than 20 million tons of it - heavier than 200 fully loaded aircraft carriers - floated in surface waters and some of which wreaked havoc on shorelines lining the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida.

The team also used environmental and field data to suggest that the belt forms seasonally in response to two key nutrient inputs: one human-derived, and one natural. In the spring and summer, Amazon River discharge adds nutrients to the ocean, and such discharged nutrients may have increased in recent years due to increased deforestation and fertilizer use. In the winter, upwelling off the West African coast delivers nutrients from deep waters to the ocean surface where the Sargassum grows.

"The evidence for nutrient enrichment is preliminary and based on limited field data and other environmental data, and we need more research to confirm this hypothesis," said Dr. Chuanmin Hu of the USF College of Marine Science, who led the study and has studied Sargassum using satellites since 2006. "On the other hand, based on the last 20 years of data, I can say that the belt is very likely to be a new normal," said Hu.

Hu spearheaded the work with first author Dr. Mengqiu Wang, a postdoctoral scholar in his Optical Oceanography Lab at USF. The team included others from USF, Florida Atlantic University, and Georgia Institute of Technology. The data they analyzed from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) between 2000-2018 indicates a possible regime shift in Sargassum blooms since 2011.

"The scale of these blooms is truly enormous, making global satellite imagery a good tool for detecting and tracking their dynamics through time," said Woody Turner, manager of the Ecological Forecasting Program at NASA Headquarters in Washington.

In patchy doses in the open ocean, Sargassum contributes to ocean health by providing habitat for turtles, crabs, fish, and birds and producing oxygen via photosynthesis like other plants. "In the open ocean, Sargassum provides great ecological values, serving as a habitat and refuge for various marine animals. I often saw fish and dolphins around these floating mats," Wang said.

But too much of this seaweed makes it hard for certain marine species to move and breathe, especially when the mats crowd the coast. When it dies and sinks to the ocean bottom at large quantities it can smother corals and seagrasses. On the beach, rotten Sargassum releases hydrogen sulfide gas and smells like rotten eggs, potentially presenting health challenges for people on beaches who have asthma, for example.

2011: A Tipping Point

Before 2011, most of the pelagic Sargassum in the ocean was primarily found floating in patches around the Gulf of Mexico and Sargasso Sea. The Sargasso Sea is located on the western edge of the central Atlantic Ocean and named after its popular algal resident. Christopher Columbus first reported Sargassum from this crystal-clear ocean in the 15th century, and many boaters of the Sargasso Sea are familiar with this seaweed.

In 2011, Sargassum populations started to explode in places it hadn't been before, like the central Atlantic Ocean, and it arrived in gargantuan gobs that suffocated shorelines and introduced a new nuisance for local environments and economies. Some countries, such as Barbados, declared a national emergency last year because of the toll this once-healthy seaweed took on tourism.

"The ocean's chemistry must have changed in order for the blooms to get so out of hand," Hu said. Sargassum reproduces vegetatively, and it probably has several initiation zones around the Atlantic Ocean. It grows faster when nutrient conditions are favorable and when its internal clock ticks in favor of reproduction.

To unravel the mystery, the team analyzed fertilizer consumption patterns in Brazil, Amazon deforestation rates, Amazon River discharge, two years of nitrogen and phosphorus measurements taken from the central western parts of the Atlantic Ocean, among other ocean properties.

While the data are preliminary, the pattern seems clear: the explosion in Sargassum correlates to increases in deforestation and fertilizer use, both of which have increased since 2010.

A Recipe for a Doom and Gloom Bloom

The team identified key factors that are critical to bloom formation: a large seed population in the winter left over from a previous bloom, nutrient input from West Africa upwelling in winter, and nutrient input in the spring or summer from the Amazon River. In addition, Sargassum only grows well when salinity is normal and surface temperatures are normal or cooler.

The 2011 bloom was likely caused by Amazon River discharge in previous years, Wang said, but was driven to even larger proportions by the double whammy of upwelling in the eastern Atlantic and river discharge on the western Atlantic.

As noted in the satellite imagery, major blooms occurred in every year between 2011 and 2018 except 2013 - and the cocktail of ingredients necessary explains why. No bloom occurred in 2013 because the seed populations measured during winter of 2012 were unusually low, Wang said.

Hu also explained why the tipping point started in 2011 instead of 2010, even on the heels of significant Amazon discharge in 2009. Significant rain in 2009 introduced freshwater to the ocean, which reduced salinity. Plus, in 2010 the sea surface temperature was higher than normal. Sargassum didn't bloom in either 2009 or 2010 because these conditions do not favor Sargassum growth.

"This is all ultimately related to climate change because it affects precipitation and ocean circulation and even human activities, but what we've shown is that these blooms do not occur because of increased water temperature," Hu said. "They are probably here to stay."

The team reports that a more detailed seasonal pattern likely to be recurring looks like this:

January: Sargassum in Central Atlantic provides the seeds for the subsequent spring-summer blooms

Jan-April: Sargassum develops into a bloom extending to the tropical Atlantic (some may reach Caribbean)

Apr - July: Blooms continue to develop into a Great Atlantic Sargassum Belt (extends northwestward by the North Brazil Current and North Equatorial Current, and eastward to the West Africa coast by the North Equatorial Counter Current)

After July: Bloom continues to the eastern Atlantic while overall abundance begins to decrease

Sept-Oct: Bloom gradually dissipates

Winter: Either the mats dissipate (as in 2012) or contribute to new blooms in the coming year

No Crystal Ball and More Work Needed

The Sargassum bloom in the Caribbean during the early parts of this year was even worse than last year, Hu said, and it's likely to impact holiday vacations in the northern Caribbean and south Florida, including Dominican Republic, Puerto Rico, Jamaica, Quintana Roo, Florida Keys, Miami Beach, and Palm Beach.

In general, predicting future blooms is difficult, Hu said, because the blooms depend on a wide-ranging spectrum of factors that are hard to predict. There's a lot left to understand, too, such as whether and how the Sargassum belt affects fisheries.

"We hope this provides a framework for improved understanding and response to this emerging phenomenon," Hu said. "We need a lot more follow-on work."

Muscle memory -- it's not just a saying. Repetitive exercise induces improved learning for motor skills, and researchers have now identified the molecular pathway underpinning the process.

The team published their paper on July 3 in the Science Advances, a journal of the American Association for the Advancement of Science.

Led by Li Zhang, an associate professor in Jinan University at Guangzhou, China, the researchers zoned in on the mechanistic target of rapamycin (mTOR) pathway in mice. Previous research by other scientists had identified the molecular system as a potential key to understanding how exercise helps improve learning but hadn't pinpointed the exact function.

"The mTOR pathway is already known to be involved in learning and memory process. There are also reports indicating mTOR activation inside the brain after exercise training," Zhang said, who is also a member of the Guangzhou Regenerative Medicine and Health Guangdong Laboratory. "However, our study, for the first time, provides direct in vivo evidence that exercise-activated mTOR is necessary for enhanced spinogenesis and neural plasticity."

Neurons have a hand-like protrusion on one end of their long body. The hand stretches, the fingers spread, waiting for incoming signals from other cells. The fingers are called dendrites, which can grow wispy spines--spinogenesis. The spines are memory incarnate; they store memory of a specific incoming signal that requires a quick reaction. It's similar to how a body develops antibodies to quickly defeat pathogens that it has already encountered.

Zhang and the researchers exercised mice on treadmills for an hour a day for three weeks and compared their brains to mice who sat on a still treadmill for the same amount of time. The mice who exercised had significantly more evidence of spinogenesis and stronger neural connections in the motor cortex. mTOR appears to be a critical factor in growing the spines and in keeping the brain able to make new connections and continue to grow, according to Zhang.

"Our results identify one critical intracellular pathway for the exercise mediation of cognitive functions and address the long-standing question for the role of mTOR underlying structural and functional adaptations of neural networks in response to the exercise," Zhang said. "We believe that the comprehensive understanding of mTOR pathway in exercised brain can provide us with objective targets and biomarkers for evaluating exercise efficiency."

The team's ultimate goal is to apply this information to benefit the clinical intervention of cognitive deficits in humans using exercise training.

This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Guangdong Natural Science Foundation. Kai Chen, who recently obtained his PhD degree, performed the experimental works with other graduate students from Jinan University under the supervision from Dr. Li Zhang and Prof. Kwok-Fai So. Other collaborators include researchers from the University of Hong Kong and Peking University.

New analysis of the fossilized skull of an Upper Paleolithic man suggests that he died a violent death, according to a study published July 3, 2019 in the open-access journal PLOS ONE by an international team from Greece, Romania and Germany led by the Eberhard Karls Universität Tübingen, Germany

The fossilized skull of a Paleolithic adult man, known as the Cioclovina calvaria, was originally uncovered in a cave in South Transylvania and is thought to be around 33,000 years old. Since its discovery, this fossil has been extensively studied. Here, the authors reassessed trauma on the skull--specifically a large fracture on the right aspect of the cranium which has been disputed in the past--in order to evaluate whether this specific fracture occurred at the time of death or as a postmortem event.

The authors conducted experimental trauma simulations using twelve synthetic bone spheres, testing scenarios such as falls from various heights as well as single or double blows from rocks or bats. Along with these simulations, the authors inspected the fossil both visually and virtually using computed tomography technology.

The authors found there were actually two injuries at or near the time of death: a linear fracture at the base of the skull, followed by a depressed fracture on the right side of the cranial vault. The simulations showed that these fractures strongly resemble the pattern of injury resulting from consecutive blows with a bat-like object; the positioning suggests the blow resulting in the depressed fracture came from a face-to-face confrontation, possibly with the bat in the perpetrator's left hand. The researchers' analysis indicates that the two injuries were not the result of accidental injury, post-mortem damage, or a fall alone.

While the fractures would have been fatal, only the fossilized skull has been found so it's possible that bodily injuries leading to death might also have been sustained. Regardless, the authors state that the forensic evidence described in this study points to an intentionally-caused violent death, suggesting that homicide was practiced by early humans during the Upper Paleolithic.

The authors add: "The Upper Paleolithic was a time of increasing cultural complexity and technological sophistication. Our work shows that violent interpersonal behaviour and murder was also part of the behavioural repertoire of these early modern Europeans."

An international team, led by scientists from the Max Planck Institute for the Science of Human History and the Leon Levy Expedition, retrieved and analyzed, for the first time, genome-wide data from people who lived during the Bronze and Iron Age (~3,600-2,800 years ago) in the ancient port city of Ashkelon, one of the core Philistine cities during the Iron Age. The team found that a European derived ancestry was introduced in Ashkelon around the time of the Philistines' estimated arrival, suggesting that ancestors of the Philistines migrated across the Mediterranean, reaching Ashkelon by the early Iron Age. This European related genetic component was subsequently diluted by the local Levantine gene pool over the succeeding centuries, suggesting intensive admixture between local and foreign populations. These genetic results, published in Science Advances, are a critical step toward understanding the long-disputed origins of the Philistines.

The Philistines are famous for their appearance in the Hebrew Bible as the arch-enemies of the Israelites. However, the ancient texts tell little about the Philistine origins other than a later memory that the Philistines came from "Caphtor" (a Bronze Age name for Crete; Amos 9:7). More than a century ago, Egyptologists proposed that a group called the Peleset in texts of the late twelfth century BCE were the same as the Biblical Philistines. The Egyptians claimed that the Peleset travelled from the "the islands," attacking what is today Cyprus and the Turkish and Syrian coasts, finally attempting to invade Egypt. These hieroglyphic inscriptions were the first indication that the search for the origins of the Philistines should be focused in the late second millennium BCE. From 1985-2016, the Leon Levy Expedition to Ashkelon, a project of the Harvard Semitic Museum, took up the search for the origin of the Philistines at Ashkelon, one of the five "Philistine" cities according to the Hebrew Bible. Led by its founder, the late Lawrence E. Stager, and then by Daniel M. Master, an author of the study and director of the Leon Levy Expedition to Ashkelon, the team found substantial changes in ways of life during the 12th century BCE which they connected to the arrival of the Philistines. Many scholars, however, argued that these cultural changes were merely the result of trade or a local imitation of foreign styles and not the result of a substantial movement of people.

This new study represents the culmination of more than thirty years of archaeological work and of genetic research utilizing state of the art technologies, concluding that the advent of the Philistines in the southern Levant involved a movement of people from the west during the Bronze to Iron Age transition.

Genetic discontinuity between the Bronze and Iron Age people of Ashkelon

The researchers successfully recovered genomic data from the remains of 10 individuals who lived in Ashkelon during the Bronze and Iron Age. This data allowed the team to compare the DNA of the Bronze and Iron Age people of Ashkelon to determine how they were related. The researchers found that individuals across all time periods derived most of their ancestry from the local Levantine gene pool, but that individuals who lived in early Iron Age Ashkelon had a European derived ancestral component that was not present in their Bronze Age predecessors.

"This genetic distinction is due to European-related gene flow introduced in Ashkelon during either the end of the Bronze Age or the beginning of the Iron Age. This timing is in accord with estimates of the Philistines arrival to the coast of the Levant, based on archaeological and textual records," explains Michal Feldman of the Max Planck Institute for the Science of Human History, leading author of the study. "While our modelling suggests a southern European gene pool as a plausible source, future sampling could identify more precisely the populations introducing the European-related component to Ashkelon."

Transient impact of the "European related" gene flow

In analyzing later Iron Age individuals from Ashkelon, the researchers found that the European related component could no longer be traced. "Within no more than two centuries, this genetic footprint introduced during the early Iron Age is no longer detectable and seems to be diluted by a local Levantine related gene pool," states Choongwon Jeong of the Max Planck Institute of the Science of Human History, one of the corresponding authors of the study.

"While, according to ancient texts, the people of Ashkelon in the first millennium BCE remained 'Philistines' to their neighbors, the distinctiveness of their genetic makeup was no longer clear, perhaps due to intermarriage with Levantine groups around them," notes Master.

"This data begins to fill a temporal gap in the genetic map of the southern Levant," explains Johannes Krause of the Max Planck Institute for the Science of Human History, senior author of the study. "At the same time, by the zoomed-in comparative analysis of the Ashkelon genetic time transect, we find that the unique cultural features in the early Iron Age are mirrored by a distinct genetic composition of the early Iron Age people."

Pain signals can travel as fast as touch signals, according to a new study from researchers at Linköping University in Sweden, Liverpool John Moores University in the UK, and the National Institutes of Health (NIH) in the US. The discovery of a rapid pain-signalling system challenges our current understanding of pain. The study is published in the scientific journal Science Advances.

It has until now been believed that nerve signals for pain are always conducted more slowly than those for touch. The latter signals, which allow us to determine where we are being touched, are conducted by nerves that have a fatty sheath of myelin that insulates the nerve. Nerves with a thick layer of myelin conduct signals more rapidly than unmyelinated nerves. In contrast, the signalling of pain in humans has been thought to be considerably slower and carried out by nerves that have only a thin layer of myelin, or none at all.

In monkeys and many other mammals, on the other hand, part of the pain-signalling system can conduct nerve signals just as fast as the system that signals touch. The scientists speculated whether such a system is also present in humans.

"The ability to feel pain is vital to our survival, so why should our pain-signalling system be so much slower than the system used for touch, and so much slower than it could be?" asks Saad Nagi, principal research engineer of the Department of Clinical and Experimental Medicine and the Center for Social and Affective Neuroscience (CSAN) at Linköping University.

To answer this, the scientists used a technique that allowed them to detect the signals in the nerve fibres from a single nerve cell. They examined 100 healthy volunteers and looked for nerve cells that conducted signals as rapidly as the nerve cells that detect touch, but that had the properties of pain receptors, otherwise known as nociceptors. Pain receptors are characterised by the ability to detect noxious stimuli, such as pinching and abrasion of the skin, while not reacting to light touch. The researchers found that 12% of thickly myelinated nerve cells had the same properties as pain receptors, and in these nerve cells the conduction speed was as high as in touch-sensitive nerve cells.

The next step of the scientists' research was to determine the function of these ultrafast pain receptors. By applying short electrical pulses through the measurement electrodes, they could stimulate individual nerve cells. The volunteers described that they experienced sharp or pinprick pain.

"When we activated an individual nerve cell, it caused a perception of pain, so we conclude that these nerve cells are connected to pain centres in the brain", says Saad Nagi.

The research team also investigated patients with various rare neurological conditions. One group of people had, as adults, acquired nerve damage that led to the thickly myelinated nerve fibres being destroyed, while the small fibres were spared. These patients cannot detect light touch. The scientists predicted that the loss of myelinated nerve fibres should also affect the rapidly conducting pain system they had identified. It turned out that these people had an impaired ability to experience mechanical pain. Examination of patients with two other rare neurological conditions gave similar results. These results may be highly significant for pain research, and for the diagnosis and care of patients with pain.

"It's becoming evident that thickly myelinated nerve fibres contribute to the experience of pain when it has a mechanical cause. Our results challenge the textbook description of a rapid system for signalling touch and a slower system for signalling pain. We suggest that pain can be signalled just as rapidly as touch", says Saad Nagi.

Bottom Line: Excessive fat tissue around the heart may be a risk factor for cardiovascular disease. This study looked at what effect aerobic and resistance exercise had on this fat tissue called epicardial and pericardial adipose tissue. This was a secondary analysis of a randomized clinical trial that included 50 physically inactive adults with abdominal obesity who had 12 weeks of high-intensity endurance or resistance training or no exercise as a control group for comparison. Change in fat tissue around the heart was measured by magnetic resonance imaging. Researchers report endurance and resistance training reduced epicardial adipose tissue mass but pericardial adipose tissue mass was reduced only by resistance training compared with no exercise. The study has several limitations to consider, including its small size. These findings need to be replicated in other larger studies.

Authors: Regitse Højgaard Christensen, M.D., University of Copenhagen, Denmark, and coauthors

(doi:10.1001/jamacardio.2019.2074)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Background

Cell membranes contain ion channels that regulate the permeation of various ions between the inside and outside of the cell. Ion channels are proteins, and in response to diverse stimuli, they allow specific ions to permeate. In this way the cell regulates the electric signals that form the basis of the function of muscles and the nervous system. Since a malfunction of ion channels causes a number of disorders such as myocardial infarction and epilepsy, it is important to understand the mechanism of action of molecules that hamper ion channel functions.

Scorpion venom has been found to contain more than 200 compounds that bind to K+ channels*1. Among them, AgTx2 is a peptide*2 consisting of 38 amino acid residues. Previous studies showed that by binding to the K+ channel from outside the cell membrane, AgTx2 blocks the K+ channel pore and inhibits K+ permeation. However, the detailed molecular mechanism remained unknown, e.g. whether the binding dynamics could be explained by a two-state model of association and dissociation.

Results

The present research team, including scientists from Kanazawa University, visualized the association and dissociation of AgTx2 with the K+ channel KcsA*3 using high-speed atomic force microscopy (HS-AFM)*4 and performed a detailed analysis of the dynamics (Figure 1). KcsA is a tetramer, its subunits forming a ring-like structure. Upon AgTx2 binding to the tetramer surface, the central part of the channel, i.e. the passage for K+, appeared swollen due to AgTx2 binding. The binding and dissociation of AgTx2 to the K+ channel could take place repeatedly and the height around the channel center changed accordingly (Figure 2). When the AgTx2 concentration in the solution was high, the binding probability was also high. Time courses of the binding and dissociation revealed that upon binding of AgTx2 to KcsA, the conformation of KcsA changed, which allowed AgTx2 binding more easily, and that even upon dissociation of AgTx2, another AgTx2 molecule could bind to KcsA very quickly; this is referred to as an induced-fit*5 mechanism. On the other hand, it was observed that, when sufficient time elapsed after AgTx2 dissociation, the conformation of KcsA changed back to the original, to which AgTx2 bound less readily. These results indicate that the binding dynamics cannot be explained with a simple two state model, i.e. binding and dissociation. It seemed that both the association and dissociation states of KcsA could be distinguished as at least two sub-states; a four state association model was therefore considered (Figure 3). When the reaction rates were calculated for a four-state model the rates obtained reflected those obtained experimentally. A simulation of the binding dynamics with this four-state model and the associated reaction rates, showed AgTx2 binding to be primarily via the induced-fit pathway. Further, it was found that the induced-fit accelerated AgTx2 binding by 400-fold. Thus, the mechanism of AgTx2 to efficiently inhibit the function of KcsA has been elucidated (Figure 3).

Future prospects

The HS-AFM observation technique and method used for the analysis of binding of the K+ channel and the peptide inhibitor can be applied to a wide variety of biological molecules. They can be applied to analyses of a ligand binding to its receptor as well as association of DNA and a DNA-binding protein. This study is expected to accelerate the elucidation of binding dynamics of various biological molecules.

Findings published today in the journal Science Translational Medicine suggest that a type of white blood cell called tumor associated macrophages (TAMs) that have been deceived by pancreatic cancer cells into not attacking them can be "re-programmed" by a specially designed molecule that activates a protein found on their surfaces.

Researchers hope that this immune system boosting molecule -- ADH-503--can eventually also make the checkpoint inhibitor immunotherapies that revolutionized the treatment of many cancers available to pancreatic cancer patients. Pancreatic cancer is the third deadliest cancer in the United States, but has shown to not respond to most current immunotherapies.

The paper "Agonism of CD11b reprograms innate immunity to sensitize pancreatic cancer to immunotherapies" was collaboration between Washington University School of Medicine in St. Louis and Rush University Medical Center in Chicago. Co-senior authors are David DeNardo, PhD, an associate professor of medicine and of pathology and immunology at Washington University and Vineet Gupta, PhD, of Rush's Vice Chair for Research and Innovation in the Department of Internal Medicine.

The authors describe how the novel ADH-503 compound interferes with the migration and polarization of myeloid cells - a type of immune system cell that circulates through the body identifying and attacking pathogens like cancer. One type of myeloid cell called macrophages (Greek for "big eaters") that are present in the tumors were a particular focus, as cancer cells are especially adept at disrupting the processes in which macrophages are able to control tumor growth.

In myeloid cells, including macrophages, a receptor protein called CD11b plays a central role in recruiting them to tumors and in detecting threats and signaling whether the immune system should respond. In pancreatic cancer tumors, the number of macrophages that help tumors grow far outnumber those that suppress them.

ADH-503 binds with and activates the CD11b receptor proteins on the myeloid cell surface. When the researchers orally delivered the ADH-503 compound to mice with pancreatic cancer, the number of myeloid cells in and near the tumors dropped, and the remaining myeloid cells were shown to be ones that promoted, rather than suppressed, immune responses. This environment translated into greater numbers of cancer-killing T cells in the tumor, significantly slower tumor growth and longer survival.

"We believe these data demonstrate that targeting the CD11b receptor with a novel molecule can decrease TAM density and reprogram myeloid cell responses to reduce tumor growth. It also overcomes resistance to T-Cell mediated therapies." Dr. Gupta said.

The researchers then investigated whether creating this same environment could make pancreatic tumors susceptible to standard immunotherapy. First, they treated a control group of mice with checkpoint inhibitor (PD-1 inhibitor) immunotherapy used to treat other kinds of cancer. There was no measurable effect. But when the therapy was combined with the ADH-503 compound, the tumors shrank and the mice survived significantly longer.

While pancreatic cancer is the third leading cause of cancer-related death in the United States, only 89 of more than 2,600 (or about 3%) 2,600 cancer immunotherapies clinical trials target pancreatic cancer

"Pancreatic cancer is a highly lethal disease and we are in desperate need of new therapeutic approaches," said DeNardo. "In animal studies, this small molecule led to very marked improvements and was even curative in some cases. We are hopeful that this approach could help pancreatic cancer patients."

Two distinct subtypes discovered, each with dramatically different risks of recurrence

Patients with more aggressive subtype can be monitored vigilantly for recurrence and possible treatment, while patients with the less aggressive subtype can be advised their prognosis is excellent

BOSTON - Researchers have discovered two distinct subtypes of pancreatic neuroendocrine tumors - known as pNETs - that have dramatically different risks of recurrence following surgical treatment [or surgery]. The finding could yield predictive tests, ease anxiety in patients whose tumors are found to be unlikely to recur, while focusing vigilant follow-up monitoring on patients with pNETs having a higher rate of recurrence.

Until now, these pancreatic neuroendocrine tumors were viewed as relatively identical from a clinical point of view. While some pNETs never develop recurrent metastases following removal of the primary tumor, other patients experience recurrence within a few years, and there has been no specific way to predict these outcomes. Physicians use tumor size as a guideline, with non-functional pNETs larger than 2 centimeters considered the most likely to metastasize following surgery.

Reporting in Nature Medicine, scientists led by Ramesh Shivdasani, MD, PhD, of Dana-Farber Cancer Institute and Bradley Bernstein, MD, PhD, of Massachusetts General Hospital identified molecular information that may help predict the likelihood of recurrence of non-functional pancreatic neuroendocrine tumors. Non-functional pNETs do not secrete hormones and are often discovered incidentally.

"This finding moves us closer to being able to identify patients with a high risk for metastasis at diagnosis and initial treatment," said Shivdasani. "These patients can be monitored vigilantly for recurrent cancers, which may be treatable if detected early, while patients with the less aggressive kind of pNET can be advised that their prognosis is excellent - we can say, 'you are probably cured."

The researchers used molecular analytical methods to describe new subtypes of pNETS that differ in the expression of specific regulatory proteins and found that the differences correlated with the risk of recurrence following surgical treatment. The regulatory proteins, ARX and PDX1, are epigenetic modifiers that are involved in development of the pancreas. The scientists found that tumors whose cells exclusively expressed the protein ARX had more than a 35 percent risk of recurrence following surgery, compared to less than a 5 percent risk if the tumor lacked ARX but expressed another regulatory protein, PDX1. Among study participants whose tumors showed high ARX levels, cancers recurred in the liver within one to four years, compared to the rare recurrence of tumors that expressed PDX1.

Pancreatic neuroendocrine tumors develop from cells of the same hormonal system within the pancreas that controls blood sugar levels. They are relatively rare, making up only one to two percent of all pancreatic tumors. Many pNETs are benign, while some are malignant. Some pNETs secrete hormones and are termed functional, but the majority are considered non-functional.

Shivdasani and his colleagues studied molecular findings first in about a dozen pNETs and then analyzed the molecular profiles of another 142 pNET specimens. They found that about half of the pNETs expressed the regulatory protein ARX and resembled normal alpha cells in the pancreas, while the other half expressed the PDX1 regulatory protein and resembled normal beta pancreatic cells. The presence or absence of those proteins was strongly correlated with outcomes: among 103 cases the researchers studied, distant metastatic relapses occurred almost exclusively in patients whose tumors expressed the ARX protein but not the PDX1 protein.

"This robust molecular stratification provides insight into cell lineage correlates of non-functional pNETs, accurately predicts disease course, and can inform postoperative clinical decisions," the authors wrote.

On the basis of these findings, said Shivdasani, pathologists could easily test specimens of pNET tumors to classify them as type A (expressing ARX) or type B (expressing PDX1). "Now you can tell patients with type B that your recurrence risk after surgery is very small - you're practically home free," Shivdasani said. "Knowing that is very comforting." For patients whose tumors are type A, with a higher risk of recurrence, close follow-up could be undertaken to detect new metastases, which may be able to be treated with chemotherapy or other methods. "And even with metastatic disease," he added, "people can live more than five years, in some cases even 10 years or longer," he said.

An immune mechanism that makes babies more likely than adults to die from sepsis has been identified by scientists affiliated with the Center for Research on Inflammatory Diseases (CRID in Ribeirão Preto, São Paulo State (Brazil). The study is published) in Critical Care.

The scientists are planning to test new therapeutic approaches based on the discovery. "We're designing a clinical trial with drugs that have been approved for human use and are known to induce this immune mechanism.The goal is to improve the survival rate for infants with sepsis," said Fernando de Queiroz Cunha, CRID's principal investigator. CRID is one of the Research, Innovation and Dissemination Centers (RIDCs funded by São Paulo Research Foundation - FAPESP.

Sepsis (sometimes referred to as blood poisoning) is systemic inflammation usually triggered by a localized bacterial infection that spins out of control. The body's immune response to combat the pathogen ends up damaging multiple organs and tissues.

Symptoms include fever or low temperature, difficulty breathing, low blood pressure, a fast heart rate, and an abnormally high or low white blood cell count. The condition may remain active even after the initial threat has been eliminated. Its most severe form can lead to lesions that impair the function of vital organs, septic shock and death.

"In any experimental animal model of sepsis, all the parameters used to measure the severity of the condition are higher in infants. There's more systemic inflammatory response, more organ impairment, and higher mortality," said Cunha, who is a Full Professor in the Department of Pharmacology at the University of São Paulo's Ribeirão Preto Medical School (FMRP-USP).

In humans, it is more difficult to compare infant and adult mortality rates, he explained, because, before contracting sepsis, the adult patient may have been weakened by diseases such as diabetes, cancer, heart failure or hypertension (high blood pressure). "Most adults who die as a result of septic shock already had serious health problems," Cunha told.

Given their knowledge that organ injury is more severe in young individuals, both human and murine, the group decided to determine exactly what substances are produced by the immune system during sepsis. Their hypothesis was that defense cells in infants must produce more oxidizing substances, such as oxygen and nitrogen free radicals. What they found, however, was the opposite.

"We took a long time to understand why infants have more tissue injury if they produce smaller amounts of free radicals. Finally, we decided to investigate NETs [neutrophil extracellular traps]," Cunha said.

Neutrophils are white blood cells that form the front line of the immune system, phagocytosing (killing) bacteria, fungi and viruses. NETs are structures composed of DNA and granular proteins that rapidly trap and kill pathogens.

"This immune mechanism was first described about ten years ago. In some situations, for poorly understood reasons, the immune system activates an enzyme called PAD-4, which increases the permeability of the neutrophil nucleus. When this happens, the genetic material in the nucleus decondenses and forms networks, which are released by the cell into the extracellular medium to trap and kill bacteria," Cunha said.

NETs are typically activated by bacterial infections, he added, as well as some viruses, including chikungunya, the arbovirus that causes the most tissue injury. The mechanism also occurs in some autoimmune disorders. "The main problem is that NETs aren't just toxic for pathogens: they also damage human cells. In fact, they do more damage than oxygen and nitrogen free radicals."

Tests involving pediatric patients were conducted in collaboration with a research group led by Professor Ana Paula Carlotti, attached to the ICU at FMRP-USP's teaching and general hospital (Hospital das Clínicas). Laboratory analysis showed that neutrophils from infants produced 40% more NETs than those taken from adults, in the case of humans. The difference was 60% in mice. The group then set out to use experimental models to understand how this immune mechanism works in sepsis.

Traps deactivated

The experiments with mice involved a group of two-week-old infants and a group of healthy young adults. Both received an intraperitoneal injection of intestinal bacteria and developed sepsis.

"A dose of bacteria sufficient to kill 100% of infants killed only 50% of the adults. That's a significant difference. Moreover, in the days following the injection, the infant mice displayed higher levels of bacteremia [bacteria in the bloodstream] and of biochemical markers indicating organ injury," Cunha said.

When NETs were broken down with recombinant human DNase (a drug used to treat cystic fibrosis), the survival rate jumped from 0 to 50% in the infant group. In the adult group, the proportion of mice that survived sepsis rose from 50% to 60%.

"The difference between the groups when treated with DNase was small, clearly showing that greater infant susceptibility is associated with higher levels of NETs," Cunha said.

In another experiment, the group replaced DNase with a compound designed to inhibit PAD-4, the enzyme that triggers the activation of NETs. In this case, the survival rate for the infant group was 40%.

"It was somewhat less effective than DNase because it's not actually a specific PAD-4 inhibitor. One of our goals for future research is the development of a specific drug to inhibit PAD-4," Cunha said.

The group analyzed the expression of the PAD-4 gene, which encodes the PAD-4 enzyme, in neutrophils from patients and from mice. In both cases, PAD-4 expression was higher in infants with sepsis than in adults with the same condition. The reasons are unknown and are currently being sought by David Fernando Colón Morelo, the first author of the article. Cunha is Morelo's PhD supervisor.

Morelo has a doctoral scholarship from FAPESP and is now doing a research internship at Bonn University in Germany.

"We're also studying the role of NETs in other diseases involving organ injury, such as rheumatoid arthritis and lupus," Cunha said.

Parkinson's disease, a neurodegenerative disorder that affects more than 6 million people worldwide, is caused by the buildup of alpha-synuclein proteins in the brain. The biological function of alpha-synuclein is still not well understood, but because of its role in neurodegenerative diseases, researchers are actively studying this protein to understand the mechanisms of the disease and to look for new treatment strategies.

A new study from Elizabeth Rhoades and postdoc Melissa Birol found that when alpha-synuclein binds to extracellular glycoproteins, proteins with added sugar molecules, it can be taken up by neurons more easily. The paper also identified a specific presynaptic protein, neurexin 1β, as a key regulator in this process and a potential therapeutic target. Their findings were published in the journal PLOS Biology.

In one possible model for the pathology of Parkinson's disease, bundles of alpha-synuclein proteins, known as aggregates, form inside a neuron. This then leads to cell death and the release of alpha-synuclein protein clusters that are taken up by other neurons. Since neurodegenerative diseases have typical progression patterns, knowing how alpha-synuclein moves between neurons in the brain helps researchers understand disease propagation.

Previous work from the Rhoades lab implicated the presence of a glycan binding site on alpha-synuclein. This finding, combined with Birol's experience in analyzing protein-membrane interactions, led to this study of how alpha-synuclein interacts with cell membranes.

Birol was able to enzymatically remove specific glycans from the cell surface to see how their presence or absence would change how alpha-synuclein was taken up by neurons. The study found that when glycans were removed, the amount of alpha-synuclein clusters taken up by cells was greatly reduced.

And by analyzing giant plasma membrane vesicles, synthetic membranes derived from components of real cells that have the same protein and lipid composition, Birol was also able to see the detailed physical interactions between alpha-synuclein and glycans. "There's a structural basis for the alpha-synuclein binding to the glycan, and when the glycans are removed, it changes the nature of the interaction of alpha-synuclein with the cell membrane," explains Rhoades.

This research focused on the acetylated form of alpha-synuclein proteins, which is present in both healthy and diseased neurons and is less frequently studied. They found that the acetylated form was more effective at forming clusters of proteins inside neurons and was required for interactions with glycans. "No one's really stressed the importance of these acetylated versions," Birol says. "Generally, we need take a step back in trying to understand how this protein may be propagating between cells, and I think glycans could be an aspect."

Rhoades and Birol say that the most unexpected finding was the discovery of neurexin 1β as a potential partner in how alpha-synuclein is taken up by neurons. They hope that future research on this presynaptic protein could provide insights into new treatment strategies for Parkinson's and other neurodegenerative diseases.

In the near term, Rhoades and her group hope to obtain higher-resolution structural information of alpha-synuclein proteins bound to glycans. They also hope that this study will inspire future research on alpha-synuclein acetylation and the role of glycans in the progression of the disease and will provide an impetus to look at previously unstudied protein modifications that might be connected to Parkinson's disease.

"Some cells spontaneously internalize these [alpha-synuclein] proteins and some do not. It has generally been assumed that there are alpha-synuclein specific receptors on the cells that do internalize aggregates. That may or may not be true, but [our study] suggests that it's not just the protein receptors but the glycans that are also important," says Rhoades.

Very little is known about how the onset of puberty is controlled in humans, but the discovery of a new gene in the roundworm C. elegans could be the "missing link" that determines when it's time to make this juvenile-to-adult transition. Two genes, LIN28 and MKRN3, are known to be associated with precocious puberty in humans, where juveniles as young as six may start developing adult features. These genes are found in all animals, including C. elegans, in which they also control the juvenile-to-adult transition. Until the new discovery, it was unclear how these two genes are connected.

The more obvious signs of the transition of juvenile-to-adult tend to be external--body morphology, matured genitalia--but nervous system changes are also happening at the same time. In humans, the maturation of the brain during adolescence is associated with increased vulnerability to a variety of neuropsychiatric disorders, so a better understanding of these processes is important for understanding mental health as well as basic neurobiology.

Two new studies in the labs of Douglas Portman, Ph.D. at the University of Rochester Medical Center and David Fitch at New York University, published in Developmental Cell and eLife, identified a new developmental timing mechanism involving a long non-coding RNA in the microscopic roundworm C. elegans. Their research revealed a surprising new molecular mechanism that controls the timing of sex-specific changes in body shape, the maturation of neural circuits, and behavior.

C. elegans has long been used by researchers to understand fundamental mechanisms in biology. Many of the discoveries made using these worms apply throughout the animal kingdom and this research has led to a broader understanding of human biology. In fact, three Nobel Prizes in medicine and chemistry have been awarded for discoveries involving C. elegans.

The researchers identified a new gene that, when disrupted, delays the transition from the juvenile to the adult stage. Surprisingly, this gene, called lep-5, does not act as a protein, as most genes do. Instead, it functions as a long non-coding RNA (lncRNA), a recently discovered class of genes whose functions remain largely mysterious. The team observed that this lncRNA is important for promoting the juvenile-to-adult transition by directly interacting with LIN-28 and LEP-2, a C. elegans gene similar to MKRN3. Because the human versions of LEP-2 and LIN-28 are both involved in the timing of puberty, the new research suggests that a yet-to-be-discovered lncRNA might be essential to this process in humans as well.

In the roundworm nervous system, some neural circuits undergo a functional transition in males as they become sexually mature adults, which is critical for generating adult-specific behaviors important for reproductive success. The male tail also undergoes a change in shape that enables mating behavior. The researchers found that this same pathway controls both the functional maturation of these circuits and the shape of the tail. Roundworms carrying mutations in lep-5 become physically mature adults, but their nervous system remains arrested in the juvenile stage, and their tails retain a juvenile form.

With respect to changes in behavior, the pathway regulates this timing by acting in the nervous system itself, not in a tissue that sends timing signals to the nervous system. Moreover, individual neurons manage their own developmental clocks. A timed "pulse" of lep-5 activity during the juvenile stage causes LIN-28 to become inactive, allowing the transition to adulthood to proceed.

Continued studies of the mechanisms identified in these studies will help scientists better understand the ways in which genetic and environmental cues regulate the transition to adulthood in humans. This research was supported by the National Institute of General Medical Sciences and National Science Foundation grants to Portman and Fitch.