A team of researchers including some from TU Delft has now investigated one of these processes in detail: the emergence and development of damage/cracks in part of the glaciers and how this process of cracking reinforces itself. They are publishing about this in the Proceedings of the National Academy of Sciences.

Satellite imagery

The researchers have combined satellite imagery from various sources to gain a more accurate picture of the rapid development of damage in the shear zones on the ice shelves of Pine Island and Thwaites. This damage consists of crevasses and fractures in the glaciers, the first signs that the shear zones are in the process of weakening. Modelling has revealed that the emergence of this kind of damage initiates a feedback process that accelerates the formation of fractures and weakening.

Unstable

According to the researchers, this process is one of the key factors that determines the stability — or instability- of the ice sheets, and thus the possible contribution of this part of Antarctica to rising sea levels. They are calling for this information to be taken into account in climate modelling, in order to improve predictions of the contribution these glaciers are making to rising sea levels.

Read more at: https://tudelft.pageflow.io/pig-damage

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River ecosystems are frequently fragmented by dams and weirs. As a result, native fish are often restricted in their movement along the river course and are unable to colonize new habitats. Thus, barriers impede native species from adjusting their distributions in response to the effects of climate change such as changes in water temperature and quality.

On the other hand, river fragmentation might also limit the further spread of invasive alien species. Using the Ebro River in Spain as an example, the research team has investigated how habitats of native and alien fish species change under different climate scenarios and how dams mediate habitat accessibility.

“The Ebro River is particularly vulnerable and threatened by climate change and species invasions. In addition, the Ebro River is fragmented by over 300 dams and many smaller barriers, which makes it even worse for the native fish species,” said Emili García-Berthou, Professor at the University of Girona and co-author of the study.

By applying a spatial modelling framework, the authors showed that losses of native species and gains of alien species and consequentially most pronounced biodiversity changes are particularly expected in the lower and mid reaches of larger Ebro River tributaries. According to their results, the majority of species are projected to shift their range in upstream direction with alien species such as eastern mosquitofish, wels catfish and common carp showing especially large habitat gains.

“The Ebro River system is home to several endemic species that exclusively occur on the Iberian Peninsula. These species are particularly imperilled by barriers that limit movements in response to climate change. Whether dams can effectively prevent the spread of alien species is questionable. In fact, the establishment of alien fishes is often facilitated by the changed flow and habitat conditions that result from damming rivers,” said IGB researcher Johannes Radinger, lead author of the study.

The results clearly show that fish communities in highly fragmented rivers affected by climate change will be particularly affected by biodiversity changes and species loss in the future. “Effective conservation of fishes should focus on the restoration of habitats and the natural flow regime, improvements of connectivity for native species and the control of alien species, particularly the prevention of further introductions,” concluded the authors.

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The findings, published Sept. 14 in Nature Immunology, indicate that elements of the immune system affect both mind and body, and that the immune molecule IL-17 may be a key link between the two.

“The brain and the body are not as separate as people think,” said senior author Jonathan Kipnis, PhD, the Alan A. and Edith L. Wolff Distinguished Professor of Pathology and Immunology and a professor of neurosurgery, of neurology and of neuroscience. “What we’ve found here is that an immune molecule — IL-17 — is produced by immune cells residing in areas around the brain, and it could affect brain function through interactions with neurons to influence anxiety-like behaviors in mice. We are now looking into whether too much or too little of IL-17 could be linked to anxiety in people.”

IL-17 is a cytokine, a signaling molecule that orchestrates the immune response to infection by activating and directing immune cells. IL-17 also has been linked to autism in animal studies and depression in people.

How an immune molecule like IL-17 might influence brain disorders, however, is something of a mystery since there isn’t much of an immune system in the brain and the few immune cells that do reside there don’t produce IL-17. But Kipnis, along with first author and postdoctoral researcher Kalil Alves de Lima, PhD, realized that the tissues that surround the brain are teeming with immune cells, among them, a small population known as gamma delta T cells that produce IL-17. They set out to determine whether gamma-delta T cells near the brain have an impact on behavior. Kipnis and Alves de Lima conducted the research while at the University of Virginia School of Medicine; both are now at Washington University.

Using mice, they discovered that the meninges are rich in gamma-delta T cells and that such cells, under normal conditions, continually produce IL-17, filling the tissues surrounding the brain with IL-17.

To determine whether gamma-delta T cells or IL-17 affect behavior, Alves de Lima put mice through established tests of memory, social behavior, foraging and anxiety. Mice that lacked gamma-delta T cells or IL-17 were indistinguishable from mice with normal immune systems on all measures but anxiety. In the wild, open fields leave mice exposed to predators such as owls and hawks, so they’ve evolved a fear of open spaces. The researchers conducted two separate tests that involved giving mice the option of entering exposed areas. While the mice with normal amounts of gamma-delta T cells and levels of IL-17 kept themselves mostly to the more protective edges and enclosed areas during the tests, mice without gamma-delta T cells or IL-17 ventured into the open areas, a lapse of vigilance that the researchers interpreted as decreased anxiety.

Moreover, the scientists discovered that neurons in the brain have receptors on their surfaces that respond to IL-17. When the scientists removed those receptors so that the neurons could not detect the presence of IL-17, the mice showed less vigilance. The researchers say the findings suggest that behavioral changes are not a byproduct but an integral part of neuro-immune communication.

Although the researchers did not expose mice to bacteria or viruses to study the effects of infection directly, they injected the animals with lipopolysaccharide, a bacterial product that elicits a strong immune response. Gamma-delta T cells in the tissues around the mice’s brains produced more IL-17 in response to the injection. When the animals were treated with antibiotics, however, the amount of IL-17 was reduced, suggesting gamma-delta T cells could sense the presence of normal bacteria such as those that make up the gut microbiome, as well as invading bacterial species, and respond appropriately to regulate behavior.

The researchers speculate that the link between the immune system and the brain could have evolved as part of a multipronged survival strategy. Increased alertness and vigilance could help rodents survive an infection by discouraging behaviors that increase the risk of further infection or predation while in a weakened state, Alves de Lima said.

“The immune system and the brain have most likely co-evolved,” Alves de Lima said. “Selecting special molecules to protect us immunologically and behaviorally at the same time is a smart way to protect against infection. This is a good example of how cytokines, which basically evolved to fight against pathogens, also are acting on the brain and modulating behavior.”

The researchers now are studying how gamma-delta T cells in the meninges detect bacterial signals from other parts of the body. They also are investigating how IL-17 signaling in neurons translates into behavioral changes.