Until now, scientists have not fully understood how these two types of guidance work together. An international research team has discovered that the stiffness of brain tissue can control the production of important signalling molecules. The findings, published in Nature Materials, reveal a direct link between mechanical forces and chemical signalling in the brain. This insight may also help researchers better understand how other organs develop and could eventually inspire new medical strategies.

Chemical Signals and Physical Cues Work Together

For many years, scientists have known that chemical signals guide how tissues grow and organize. Gradients of signalling molecules act like directional cues, helping cells move and develop in the correct locations.

More recent studies have shown that physical factors such as tissue stiffness also influence how cells behave. However, the relationship between these mechanical cues and chemical signals has remained unclear. Understanding how the two interact is critical for explaining how complex tissues such as the brain form during development.

Study Reveals Tissue Stiffness Controls Key Brain Signals

Researchers from the Max-Planck-Zentrum für Physik und Medizin (MPZPM), the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), and the University of Cambridge investigated this question using Xenopus laevis (African clawed frogs), a widely used model organism in developmental biology. Their experiments showed that tissue stiffness can regulate the production of important chemical guidance cues.

This process is controlled by a mechanosensitive protein called Piezo1. The team, led by Prof. Kristian Franze, found that when tissue stiffness increased, cells began producing signalling molecules that are normally absent from those areas. One example is the guidance molecule Semaphorin 3A. Notably, this response only occurred when Piezo1 levels were sufficiently high.

“We didn’t expect Piezo1 to act as both a force sensor and a sculptor of the chemical landscape in the brain,” said study co-lead Eva Pillai, a postdoctoral researcher at the European Molecular Biology Laboratory (EMBL). “It not only detects mechanical forces — it helps shape the chemical signals that guide how neurons grow. This kind of connection between the brain’s physical and chemical worlds gives us a whole new way of thinking about how it develops.”

Piezo1 Also Helps Maintain Tissue Structure

The researchers also discovered that Piezo1 influences the physical stability of brain tissue itself. When the amount of Piezo1 is reduced, levels of important cell adhesion proteins including NCAM1 and N-cadherin drop. These proteins are crucial for maintaining cell-cell contacts — which glue cells together.

“What’s exciting is that Piezo1 doesn’t just help neurons sense their environment — it helps build it,” said Sudipta Mukherjee, study co-lead and postdoctoral researcher at FAU and MPZPM. He and Pillai were both doctoral students at the University of Cambridge, where the project was initiated. “By regulating the levels of these adhesion proteins, Piezo1 keeps cells well connected, which is essential for a stable tissue architecture. The stability of the enviroment in turn, influences the chemical environment.”

The results indicate that Piezo1 performs two important roles. It acts as a sensor that converts mechanical signals from the surrounding environment into cellular responses. At the same time, it functions as a modulator that helps organize the mechanical properties of the tissue itself.

Implications for Development and Disease

These findings could have wide ranging significance for developmental biology and medical research. Errors in neuron growth are associated with congenital and neurodevelopmental disorders. In addition, tissue stiffness has been linked to diseases such as cancer.

By demonstrating that mechanical forces can shape chemical signalling, the study provides new insight into how tissues form and function. It also suggests new directions for research into disease and potential treatments.

“Our work shows that the brain’s mechanical environment is not just a backdrop — it is an active director of development,” said senior author Kristian Franze. “It regulates cell function not only directly, but also indirectly by modulating the chemical landscape. This study may lead to a paradigm shift in how we think about chemical signals, with implications for many processes from early embryonic development to regeneration and disease.”

The researchers also found that tissue stiffness can influence chemical signalling across long distances, affecting the behavior of cells far from where the mechanical force originates. Overall, the study highlights mechanical forces as a powerful regulator of development and organ function.

The research team examined how droughts begin in different parts of the world and whether they occur at roughly the same time. The study was led by Dr. Udit Bhatia of IITGN, with contributions from researchers at IITGN and the Helmholtz Centre for Environmental Research — UFZ in Leipzig, Germany.

“We treated drought onsets as events in a global network. If two distant regions entered drought within a short time window, they were considered synchronized,” explained Dr. Bhatia, the lead author and principal investigator of the Machine Intelligence and Resilience Lab and the AI Resilience and Command (ARC) Centre at IITGN.

Global “Drought Hubs” and Crop Risk

By charting thousands of these drought connections, researchers identified several regions that often act as major centers of drought activity. These so called “drought hubs” include Australia, South America, southern Africa, and parts of North America.

The team also compared climate patterns with historical agricultural data to understand how moderate drought conditions influence food production. They analyzed crop yields for wheat, rice, maize, and soybean across multiple regions.

“In many major agricultural regions, when moderate drought occurs, the probability of crop failure rises sharply — often above 25%, and in some areas, above 40-50% for crops like maize and soybean,” said Hemant Poonia, an AI Scientist at IITGN who completed his undergraduate and postgraduate degrees in Civil Engineering from the Institute.

Although such risks could become severe if drought affected many farming regions at the same time, the researchers found that natural climate processes help prevent that scenario. Changes in sea surface temperatures, particularly in the Pacific Ocean, limit how widely drought conditions spread across continents.

El Niño and La Niña Shape Global Drought Patterns

One of the strongest influences on these shifting patterns is the El Niño-Southern Oscillation, a natural warming and cooling cycle in the Pacific Ocean that affects rainfall around the world.

During El Niño phases, Australia often becomes a major drought hub, while other regions respond in different ways. When La Niña conditions develop, drought patterns shift again and tend to spread across a wider range of locations.

“These ocean-driven swings create a patchwork of regional responses, limiting the emergence of a single, global drought covering many continents at once,” explained co-author Danish Mansoor Tantary, a former IITGN master’s student who is now pursuing his PhD at Northeastern University (USA).

Rainfall and Rising Temperatures Both Affect Drought Severity

Researchers also investigated how rainfall and temperature together influence the intensity of drought. Their analysis suggests that precipitation changes account for about two thirds of long term shifts in drought severity over recent decades. The remaining third is linked to increasing evaporative demand caused by rising temperatures.

“Rainfall remains the dominant driver globally, especially in regions like Australia and South America, but the influence of temperature is clearly growing in several mid-latitude regions, such as Europe and Asia,” said Dr. Rohini Kumar, the corresponding author and senior scientist at the Helmholtz Centre for Environmental Research, whose work focuses on interactions between water, land, and climate systems.

Early Warning Signals for Global Food Security

The findings show how large scale, data driven analysis of climate patterns can help protect global food supplies. By studying drought as part of an interconnected planetary system rather than as isolated weather events, scientists can identify potential early warning regions before local droughts expand into broader crises.

Prof Vimal Mishra, a leading water and climate expert at IITGN and recipient of the Shanti Swarup Bhatnagar Prize, India’s highest multidisciplinary science award, emphasized the broader implications.

“These findings underline the importance of international trade, storage, and flexible policies. Because droughts do not hit all regions at the same time, smart planning can use this natural diversity to buffer global food supplies.”

Using Climate Insights to Reduce Future Risk

Dr. Bhatia noted that the research highlights how understanding climate systems can guide better policy decisions in a warming world.

“Our research highlights that we are not helpless in the face of a warming planet,” said Dr. Bhatia. “By understanding the delicate balance between oceans, rainfall, and temperatures, policymakers can focus their resources on specific drought hubs and create pipelines to stabilize the global market before crop failures in one region trigger price spikes in another.”

The authors acknowledged support from the Anusandhan National Research Foundation (SERB) Network of Networks grant, Projekt DEAL, and AI Centre of Excellence (AICoE) in sustainable cities.

A new and far more comprehensive analysis now challenges that timeline. By examining 17 tyrannosaur specimens ranging from young juveniles to enormous adults, researchers determined that the famous predator likely continued growing for around 40 years before reaching its maximum weight of roughly eight tons.

The study, published in the journal PeerJ, represents the most detailed reconstruction of the life history of T. rex so far. Researchers combined advanced statistical modeling with microscopic examination of bone slices. Using a specialized lighting technique, they were able to detect previously overlooked growth rings. These hidden markers allowed the team to build a more complete picture of tyrannosaur growth patterns. The findings also hint that some fossils previously classified as T. rex could actually belong to different species or represent other biological differences.

Reconstructing the Life History of Tyrannosaurus Rex

“This is the largest data set ever assembled for Tyrannosaurus rex,” says Holly Woodward, a professor of anatomy at Oklahoma State University who led the research effort. “Examining the growth rings preserved in the fossilized bones allowed us to reconstruct the animals’ year-by-year growth histories.”

However, the fossil record does not preserve the entire lifespan of an individual animal. Unlike the full sequence of rings visible in a tree trunk, a cross section of T. rex bone typically captures only the final 10 to 20 years of the dinosaur’s life.

To fill those gaps, the researchers developed a new analytical method. By combining growth information from multiple specimens of different ages, they created a composite growth curve for the species.

“We came up with a new statistical approach that stitches together growth records from different specimens to estimate the growth trajectory of T. rex across all stages of life in greater detail than any previous study,” explains Nathan Myhrvold, a mathematician and paleobiologist at Intellectual Ventures who led the statistical analysis. “The composite growth curve provides a much more realistic view of how Tyrannosaurus grew and how much they varied in size.”

A Longer Growth Period for the King of Dinosaurs

The results suggest that Tyrannosaurus did not rapidly reach adulthood. Instead, the dinosaurs appear to have grown gradually over several decades.

Rather than maturing quickly, T. rex experienced a prolonged growth phase lasting roughly four decades. According to the researchers, this extended development may have played an important ecological role.

“A four-decade growth phase may have allowed younger tyrannosaurs to fill a variety of ecological roles within their environments,” says coauthor Jack Horner of Chapman University. “That could be one factor that allowed them to dominate the end of the Cretaceous Period as apex carnivores.”

Could Some Famous Fossils Belong to Other Species

Although Tyrannosaurus rex is the best known species in this group of dinosaurs, scientists continue to debate whether some fossils assigned to T. rex actually belong to closely related species.

Some researchers have proposed that certain smaller fossils represent a distinct species called Nanotyrannus rather than young Tyrannosaurus individuals. Others have suggested that even the largest specimens might belong to two or three separate species.

These ideas remain controversial within the scientific community.

To explore the issue further, the new study examined 17 specimens within what researchers describe as the “Tyrannosaurus rex species complex.” This term acknowledges the possibility that the fossils may represent multiple related species or subspecies.

One notable result involves two well known fossils nicknamed “Jane” and “Petey.” Their growth patterns differ significantly from those of the other specimens in the dataset. While growth data alone cannot prove that they represent separate species, the difference raises intriguing questions. A separate recent analysis by Zanno and Napoli reached a similar conclusion using different techniques, identifying Jane and Petey as belonging to two distinct species of Nanotyrannus.

New Imaging Technique Reveals Hidden Growth Rings

Another key finding involves the discovery of a previously unrecognized type of growth ring in dinosaur bone. Woodward, Myhrvold, and Horner found that circularly polarized and cross-polarized light can reveal growth features that are difficult to detect with standard methods.

This approach helps clarify puzzling growth patterns seen in some specimens. The researchers supported the finding with strong statistical evidence, suggesting that traditional techniques for counting dinosaur growth rings may sometimes overlook important details.

“Interpreting multiple closely spaced growth marks is tricky,” Myhrvold says. “We found strong evidence that the protocols typically used in growth studies may need to be revised.”

A Clearer Picture of Tyrannosaurus Life

More than a century after Tyrannosaurus rex was first discovered, the species continues to surprise scientists. By combining a larger fossil sample, new analytical tools, and improved imaging methods, the research offers a clearer understanding of how these iconic predators grew and developed.

The results provide a more complete portrait of Tyrannosaurus rex as a living animal, tracing its journey from young dinosaur to one of the largest land predators in Earth’s history.