You may have missed… tiny beating human heart models; wood transistor; sea lions getting bigger; JWST finds galaxy cluster

Your hit of the best of last week’s science.

Tiny living and beating model human heart muscles

Australian researchers have successfully introduced a vascular system into tiny living and beating model human heart organoids, according to a new study in the journal Cell Reports.

The new organoids more closely mimic the human heart and will allow much more accurate testing of new drugs to treat heart disease and inflammation. It’s hoped that this will accelerate progress towards the ultimate goal of repairing tissue damage from heart disease.

“We only know a fraction about the biology underpinning the heart so we’re constantly trying to improve our cardiac organoids to simulate the heart’s complex cellular interactions and tissue composition,” explains Professor James Hudson, head of QIMR Berghofer Medical Research Institute’s Cardiac Bioengineering Research Group, and lead researcher on the paper.

“Each organoid is only about the size of a chia seed, measuring just 1.5 millimetres across, but inside are 50,000 cells representing the different cell types that make up the heart.

“Incorporating the vascular cells for the first time in our mini heart muscles is very significant because we found they had a key role in the biology of the tissues. Vascular cells made the organoids function better and beat strongly. This has really opened up our ability to better understand the heart and accurately model disease,”

The method also has broader implications that could help researchers in other fields creating organoids such as kidneys and brains.

The world’s first transistor made of wood

Researchers have developed the world’s first transistor made of wood and it can function continuously and regulate electricity flow without deteriorating.

The research is in the journal Proceedings of the National Academy of Sciences.

Transistors are a basic building block of modern electronic devices; they regulate the electric current that passes through them and function as an on/off switch. Usually they’re made of silicon, some from germanium, or sometimes other semiconductor materials.

“We’ve come up with an unprecedented principle. Yes, the wood transistor is slow and bulky, but it does work, and has huge development potential,” says Isak Engquist, senior associate professor at the Laboratory for Organic Electronics at Linköping University, Sweden, and senior author of the paper.

A person wearing glasses holds up a cross-shaped wooden transistor
Researchers at Linköping University, together with colleagues from the KTH Royal Institute of Technology, have now developed the world’s first electrical transistor made of wood. Credit: Thor Balkhed

The wood transistor is able to regulate electric current and operate continuously at the selected output level. It can also switch the power on and off, albeit with a certain delay – switching it off took about a second, and switching it on about five seconds. 

Possible applications could include regulating electronic plants, but Engquist stresses that they didn’t create the wood transistor with any specific application in mind.

“We did it because we could. This is basic research, showing that it’s possible, and we hope it will inspire further research that can lead to applications in the future.”

Male California sea lions are getting bigger, going against usual animal expectations

Animals tend to get smaller as their populations grow because of increased competition for food resources. Unexpectedly, new research in Current Biology has found that male California sea lions (Zalophus californianus) buck this trend.

“It’s counterintuitive. You would expect that their body size would decrease as dietary resource competition intensified,” says co-author Paul Koch, professor of Earth and Planetary Sciences at the University of California – Santa Cruz, in the US.

The population of these animals has increased dramatically since the Marine Mammal Protection Act was passed in 1972, and in parts of their range may even be approaching the capacity of ecosystems to support them.

A table full of rows of sea lion skulls
California sea lion skulls used for this study at the Ornithology and Mammalogy Collection of the California Academy of Sciences. Credit: Ana Valenzuela Toro

First author Ana Valenzuela-Toro looked at the size and morphology of sea lion skulls collected between 1962 and 2008 in central California, and analysed bone samples for clues to changes in the animals’ diets.

“We found that male California sea lions have expanded their ecological niche, which means they are now foraging on a more diversified group of prey and expanding the places where they are foraging,” says Valenzuela-Toro, who is a PhD candidate in Ecology and Evolutionary Biology at UC Santa Cruz.

In theory this allows them to be able to travel further, dive deeper, and handle larger prey, and as their breeding sites became more crowded, increased competition between males during the breeding season may have also favoured larger males over time.

An early-universe prequel to huge galaxy cluster

The James Webb Space Telescope (JWST) has revealed, for the first time, a proto-cluster of seven galaxies at a distance from Earth that corresponds to only 650 million years after the big bang.

Based on the data collected, the researchers were able to confirm that the galaxies all reside within a radius of 60 kiloparsecs (195, 694 light years) and are moving at speeds of about one thousand kilometres per second.

An image of many galaxies against the black backdrop of space
The seven galaxies highlighted in this James Webb Space Telescope image have been confirmed to be at a distance that astronomers refer to as redshift 7.9, which correlates to 650 million years after the big bang. This makes them the earliest galaxies yet to be spectroscopically confirmed as part of a developing cluster. Credit: NASA, ESA, CSA, T. Morishita (IPAC). Image processing: A. Pagan (STScI)

“This is a very special, unique site of accelerated galaxy evolution, and Webb gave us the unprecedented ability to measure the velocities of these seven galaxies and confidently confirm that they are bound together in a proto-cluster,” says Dr Takahiro Morishita of the Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology, and the lead author of the study in the Astrophysical Journal Letters.

Based on the data collected, they calculated the cluster’s future development and found that it will likely grow in size and mass to resemble the Coma Cluster – one of the densest known galaxy collections in the universe.

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