Wednesday, October 04, 2023

 

Origin of cultural learning: Babies imitate because they are imitated


Peer-Reviewed Publication

LUDWIG-MAXIMILIANS-UNIVERSITÄT MÜNCHEN




LMU study shows that babies learn to imitate others because they themselves are imitated by caregivers

People are constantly learning from others without even being aware of it. Social learning avoids laborious trial and error; the wheel does not have to be reinvented each time. But where does this ability come from, which forms the basis of cultural learning and consequently for the evolutionary success of the human species? A study led by Professor Markus Paulus.

Chair of Developmental Psychology and Educational Psychology at LMU, demonstrates that the ability has its roots in earliest childhood. “Children acquire their ability to imitate because they themselves are imitated by their caregivers,” says Markus Paulus.

Children are incredible imitators – thanks to their parents

For the study, the researchers looked at the interaction between mother and child over several months. The babies came into the lab for the first time at the age of 6 months, while their final visit was when they were 18 months old. As they engaged in various play situations, the interactions and imitations of mother and child were analyzed.

The longitudinal study shows that the more sensitive a mother was in her interactions with her six-month-old child and the more often she imitated the infant, the greater the child’s ability was at the age of 18 months to imitate others.

In the interaction between parents and child, mutual imitation is a sign of communication. Parents respond to the signals given by the child and reflect and amplify them. A mutual imitation of actions and gestures develops. “These experiences create connections between what the child feels and does on the one hand and what it sees on the other. Associations are formed. The child’s visual experience is connected to its own motor activity,” says Markus Paulus, explaining the neuro-cognitive process.

Children learn a variety of skills through imitation, such as how to use objects, cultural gestures like waving, and the acquisition of language. “Children are incredible imitators. Mimicry paves the way to their further development. Imitation is the start of the cultural process toward becoming human,” says Markus Paulus. In psychology, the theory that the ability to imitate is inborn held sway for a long time. The LMU study is further evidence that the ability is actually acquired.

 

The cultural transfer of knowledge is based on imitation

How well children learn to imitate others is crucially dependent on the sensitivity with which their parents respond to them. In this context, sensitivity is defined as the capability of a caregiver to pick up on the child’s signals and react promptly and appropriately to them. “The sensitivity of the mother is a predictor of how strongly she imitates her child,” says Dr. Samuel Essler, lead author of the study.

In addition, the study sheds light on what makes humans social beings, namely that our individual abilities only develop through interaction with others. Indeed, they owe their existence to the particular way in which humans raise their young.

“By being part of a social interaction culture, in which they are imitated, children learn to learn from others. Over the course of generations and millennia, this interplay has led to the cultural evolution of humans,” says Markus Paulus. “Through social learning, certain actions or techniques do not have to be constantly invented anew, but there is a cultural transfer of knowledge. Our results show that the ability to imitate, and thus cultural learning, is itself a product of cultural learning, in particular the parent-child interaction.”

 

Sperm swimming is caused by the same patterns that are believed to dictate zebra stripes


Peer-Reviewed Publication

UNIVERSITY OF BRISTOL

Fig 1 

IMAGE: GRAPH view more 

CREDIT: HERMES GADÊLHA




Patterns of chemical interactions are thought to create patterns in nature such as stripes and spots. This new study shows that the mathematical basis of these patterns also governs how sperm tail moves.

The findings, published today in Nature Communications, reveal that flagella movement of, for example, sperm tails and cilia, follow the same template for pattern formation that was discovered by the famous mathematician Alan Turing. 

Flagellar undulations make stripe patterns in space-time, generating waves that travel along the tail to drive the sperm and microbes forward.

Alan Turing is most well-known for helping to break the enigma code during WWII. However he also developed a theory of pattern formation that predicted that chemical patterns may appear spontaneously with only two ingredients: chemicals spreading out (diffusing) and reacting together. Turing first proposed the so-called reaction-diffusion theory for pattern formation.

Turing helped to pave the way for a whole new type of enquiry using reaction-diffusion mathematics to understand natural patterns. Today, these chemical patterns first envisioned by Turing are called Turing patterns. Although not yet proven by experimental evidence, these patterns are thought to govern many patterns across nature, such as leopard spots, the whorl of seeds in the head of a sunflower, and patterns of sand on the beach. Turing’s theory can be applied to various fields, from biology and robotics to astrophysics. 

Mathematician Dr Hermes Gadêlha, head of the Polymaths Lab, and his PhD student James Cass conducted this research in the School of Engineering Mathematics and Technology at the University of Bristol. Gadêlha explained: “Live spontaneous motion of flagella and cilia is observed everywhere in nature, but little is known about how they are orchestrated.

“They are critical in health and disease, reproduction, evolution, and survivorship of almost every aquatic microorganism in earth."

The team was inspired by recent observations in low viscosity fluids that the surrounding environment plays a minor role on the flagellum. They used mathematical modelling, simulations, and data fitting to show that flagellar undulations can arise spontaneously without the influence of their fluid environment.

Mathematically this is equivalent to Turing’s reaction-diffusion system that was first proposed for chemical patterns.

In the case of sperm swimming, chemical reactions of molecular motors power the flagellum, and bending movement diffuses along the tail in waves. The level of generality between visual patterns and patterns of movement is striking and unexpected, and shows that only two simple ingredients are needed to achieve highly complex motion.

Dr Gadêlha added: “We show that this mathematical 'recipe’ is followed by two very distant species – bull sperm and Chlamydomonas (a green algae that is used as a model organism across science), suggesting that nature replicates similar solutions.

“Travelling waves emerge spontaneously even when the flagellum is uninfluenced by the surrounding fluid. This means that the flagellum has a fool-proof mechanism to enable swimming in low viscosity environments, which would otherwise be impossible for aquatic species.

“It is the first time that model simulations compare well with experimental data.

“We are grateful to the researchers that made their data freely available, without which we would not have been able to proceed with this mathematical study.”

These findings may be used in future to better understand fertility issues associated with abnormal flagellar motion and other ciliopathies; diseases caused by ineffective cilia in human bodies.

This could also be further explored for robotic applications, artificial muscles, and animated materials, as the team discovered a simple 'mathematical recipe' for making patterns of movement.

Dr Gadêlha is also a member of the SoftLab at Bristol Robotics Laboratory (BRL), where he uses pattern formation mathematics to innovate the next generation of soft-robots.

“In 1952, Turing unlocked the reaction-diffusion basis of chemical patterns,” said Dr Gadêlha. “We show that the ‘atom’ of motion in the cellular world, the flagellum, uses Turing's template to shape, instead, patterns of movement driving tail motion that pushes sperm forwards.

“Although this is a step closer to mathematically decode spontaneous animation in nature, our reaction-diffusion model is far too simple to fully capture all complexity. Other models may exist, in the space of models, with equal, or even better, fits with experiments, that we simply have no knowledge of their existence yet, and thus substantial more research is still needed!”

The study was completed using funding from the Engineering and Physical Sciences Research Council (EPSRC) and DTP studentship for James Cass PhD

The numerical work was carried out using the computational and data storage facilities of the Advanced Computing Research Centre, at the University of Bristol.

  

Stripe patterns

Stripe patterns in space time

CREDIT

Hermes Gadêlha

video [VIDEO] | EurekAlert! 


Paper:

The reaction-diffusion basis of animated patterns in eukaryotic flagella’ by James Cass and Dr Hermes Bloomfield-Gadêlha in Nature Communications.

 

Fish reveal cause of altered human facial development


Impact of substances on zebrafish embryos shows how the prenatal development of human facial features might also be affected

Peer-Reviewed Publication

UNIVERSITY OF TOKYO

Four-day-old zebrafish 

IMAGE: THIS ZEBRAFISH LARVA HAS BEEN GENETICALLY MODIFIED SO THAT THE BONE-FORMING CELLS IN THE FACE EMIT A GREEN FLUORESCENCE. NORMALLY, THEY ARE COLORLESS AND TRANSPARENT, THUS ALMOST INVISIBLE AT THIS STAGE. AS EMBRYOS, THEIR HEAD AND TAIL START TO FORM AFTER JUST 16 HOURS. AS ADULTS, THEY GROW TO BE JUST 2-5 CENTIMETERS LONG. view more 

CREDIT: 2023 LIU ET AL.




Some substances in medicines, household items and the environment are known to affect prenatal child development. In a study published in Toxicological Sciences, researchers tested the effects of five drugs (including caffeine and the blood thinner warfarin) on the growth of zebrafish embryos. They found that all five had the same effect, impairing the migration of bone-forming cells which resulted in the onset of facial malformation. Zebrafish embryos grow quickly, are transparent and develop outside of the parent’s body, making them ideal for studying early development. A zebrafish-based system could be used to easily screen for potentially harmful substances, reducing animal testing on mammals and supporting parents-to-be when making choices for themselves and their baby.

Whether from birth or through events which happen in life, many people have differences in their facial appearance. Worldwide, over one-third of all congenital anomalies relate to the development of a child’s head or facial bones — their craniofacial features — a common example being having a cleft lip and/or palate. The exact cause of craniofacial differences is not fully understood, but researchers currently think that multiple factors may be involved. This includes genetics, the gestational parent’s environment, their diet, some illnesses and certain drugs or chemicals.

Teratogens are substances known to disturb the growth of an embryo or fetus; for example, pregnant people are advised to avoid alcohol and nicotine. Potential teratogens are typically screened for using animals such as rodents and rabbits. But researchers are looking for alternative methods which are quicker, cheaper and reduce the need for testing on mammals.

This is where zebrafish come in. These tiny, 2-5 centimeter freshwater fish grow very quickly, developing as much in a day as a human embryo would in a month. “Zebrafish embryos are transparent and grow outside the mother, so we can monitor the behavior of live cells as they develop,” said Toru Kawanishi, project assistant professor at the University of Tokyo’s Department of Biological Sciences at the time of the study. Within the past 10 years, several research projects have shown that zebrafish can effectively be used to check for teratogens. However, the exact mechanisms by which teratogens impair or alter typical embryonic development is still being investigated.

The team focused on a specific genetic marker for a group of cells involved in craniofacial development in both mammals and fish. In humans, these are known to become parts of the nose and jaw. “We manipulated the genome of zebrafish embryos and made bone-forming cells fluorescently visible in green. We then treated them with chemicals that are known to cause facial defects in human newborns, and tracked the trajectories of the bone-forming cells throughout embryonic stages,” explained Kawanishi.

The team tested five chemicals: valproic acid (used to treat neurological and psychiatric disorders), warfarin (an anticoagulant), salicylic acid (popular in skin ointments), caffeine and methotrexate (used in chemotherapy). They saw that, as expected, all the chemicals tested caused various degrees of craniofacial anomalies 96 hours after fertilization. However, they were surprised by the mechanism which caused this to happen and how quickly it started.

“Bone- and cartilage-forming cells in the head, called cranial neural crest cells (CNCCs), generally move a long distance from where they are first formed around the back of the neck, to their intended destinations such as the jaw or nose,” explained Kawanishi. “We were surprised that regardless of how each chemical acts on cells molecularly, impaired migration of bone-forming cells in early development was responsible for the onset of facial malformation for all the five chemicals. We could see signs of this within just 24 hours, at a point where zebrafish and mammalian embryos share very similar morphological and molecular characteristics.”

The results indicate the potential existence of a general mechanism by which teratogenic chemicals limit movement of CNCCs early on in embryos, causing the development of facial differences. The researchers extrapolate that facial differences caused by other substances might also follow the same mechanism. “We will aim to reveal the molecular mechanism underlying the impaired cell migration, to understand why different chemicals lead to the shared defects in cell migration,” said Kawanishi. The team proposes using this zebrafish-based system as another way to test for cross-species teratogens, so that parents and medical practitioners can be made aware to limit or avoid them.

These images show the development of a zebrafish’s craniofacial cartilage (via fluorescent staining) 96 hours post fertilization, comparing typical development (on the far left) with the effect of the five drugs tested.

These fluorescent images of live zebrafish embryos show the movement, assembly and growth of cartilage -forming cells at 48, 72 and 96 hours post fertilization.

CREDIT

2023 Liu et al.

Paper Title:

Shujie Liu, Toru Kawanishi, Atsuko Shimada, Naohiro Ikeda, Masayuki Yamane, Hiroyuki Takeda, Junichi Tasaki. “Identification of an adverse outcome pathway (AOP) for chemical-induced craniofacial anomalies using the transgenic zebrafish model” Toxicological Sciences, 2023, 1-14. DOI: 10.1093/toxsci/kfad078.

Declaration of competing interests

S.L., N.I., M.Y., and J.T. are employed by the company Kao. The author/authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Useful Links :

Graduate School of Science: https://www.s.u-tokyo.ac.jp/en/

Takeda Lab: https://www.bs.s.u-tokyo.ac.jp/~hassei/English/research%20E/research%20E.html

About the University of Tokyo
The University of Tokyo is Japan's leading university and one of the world's top research universities. The vast research output of some 6,000 researchers is published in the world's top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.
 

Climate change filtered out resource-acquisitive plants in a temperate grassland


Peer-Reviewed Publication

SCIENCE CHINA PRESS




Evidence is mounting that climate change is triggering biodiversity loss, changing community composition and ecosystem functions. However, the intricate mechanisms underpinning ecological processes remain an enigma, motivating researchers to dissect the intricate web of interactions.

Recently, in a paper published in Science China Life Sciences, a Chinese team from Peking University focused on resource-use strategies, revealing how species with different resource-use strategies would respond to climate change, and how the responses may influence community-level productivity.

 “We usually thought more species would mean more productivity. But what we’re seeing here is that species richness and functional diversity declined significantly while productivity did not significantly decline.” said Professor Wang, the lead researcher in the study. To dive into the reason behind this puzzle, the team classified species into different functional types according to plant functional traits. Resource-acquisitive plants are featured by high leaf nutrient content, large specific leaf area, and a low investment on leaf structure. In contrast, resource-conservative plant species exhibited a contrasting array of attributes.

As the climate in the studied grassland became drier and warmer, resource-acquisitive plants responded rapidly to limited water and declined their species richness and functional diversity, leading to community-level diversity decreased. In the meanwhile, resource-conservative plants, the dominating species in this grassland community, remained relatively stable, contributing to the stable productivity.

The results line up with what scientists have hypothesized before – that community-level productivity is determined by dominant species and insensitive to the decline of less abundant species. Nonetheless, Professor Wang throws in a curveball of caution, “Our findings do not mean that rare species do not matter. We can't assume that ecosystem productivity will always stay stable if the climate keeps getting warmer and drier. A continuous loss of diversity could tip the balance.”

This research enriches our understanding of plant dynamics in the face of climate change, offering insights into the nuanced interplay between resource strategies and ecological functions.

 

See the article:

Climate change filtered out resource-acquisitive plants in a temperate grassland in Inner Mongolia, China

https://doi.org/10.1007/s11427-022-2338-1

Disclaimer: AAAS and EurekAler

 

Gain-of-function allele of HPY1 coordinates source and sink to increase grain yield in rice


Peer-Reviewed Publication

SCIENCE CHINA PRESS

A proposed working model for HPY1 

IMAGE: HPY1 MUTATION ENHANCES THE TRANSCRIPTIONAL LEVEL OF ITSELF THROUGH FEEDBACK REGULATION. THEN, THE HPY1 TARGETS RBCS2, RBCS3, AND RBCS4 TO INCREASE THEIR EXPRESSION AND RUBISCO ACTIVITY, WHICH IMPROVES PHOTOSYNTHETIC EFFICIENCY AND BIOMASS ACCUMULATION IN RICE. MEANWHILE, THE HPY1 TARGETS TO CCP1 AND FLO2, KEY GENES FOR GLUME DEVELOPMENT, TO ENHANCE THEIR EXPRESSION TO INCREASE GRAIN SIZE. FINALLY, THE IMPROVED PHOTOSYNTHETIC RATE, BIOMASS ACCUMULATION AND HIGH EXPRESSION OF CCP1 AND FLO2 WORKING TOGETHER LEAD TO A HIGH GRAIN YIELD OF RICE. view more 

CREDIT: ©SCIENCE CHINA PRESS




This study is led by Prof. Shaoqing Li (State Key Laboratory of Hybrid Rice, Wuhan University).

Rice is a primary staple crop for over half of the global population, and the continual enhancement of its yield holds significant significance in ensuring world food security. Therefore, achieving sustained increases in rice production has remained a major scientific challenge in the field of rice science research. Physiologically, rice yield is jointly determined by photosynthetic capacity (source) and grain size/number (sink). However, current research predominantly focuses on either source or sink, with relatively limited studies addressing the synergy between the two.

The team led by Prof. Shaoqing Li obtained a large-grain, tall stature mutant through radiation mutagenesis. Subsequently, using positional cloning, they cloned a gene that concurrently regulates photosynthetic efficiency, grain size, biomass, and yield, naming it HPY1 (high photosynthetic rate and yield 1). HPY1 is a transcription factor derived from a transposon, highly conserved without any mutations across rice germplasm resources. A SNP variation in the coding region of this gene leads to an alteration in an amino acid of the HTH (helix-turn-helix) domain's C-terminus, causing a change in protein structure and thereby increasing its DNA binding capacity. This ultimately triggers an increase in downstream gene expression, resulting in a phenotype of high photosynthetic efficiency, large grains, high biomass, and high yield.

Further analysis revealed that HPY1 enhances rice yield by synergistically improving both source and sink. HPY1 mutation enhances the transcriptional level of itself through feedback regulation. Then, HPY1 directly binds to source-related genes (RbcS2RbcS3, and RbcS4, encoding Rubisco small subunits) to enhance their transcription, consequently increasing Rubisco content and activity, thereby raising photosynthetic rates and biomass. Simultaneously, it directly binds to sink-related genes (CCP1 and FLO2, genes regulating grain size) and upregulates their transcription, leading to larger grain size. Ultimately, relying on the simultaneous enhancement of source and sink, rice yield is increased.

In summary, this study identified a high-yielding gene, HPY1, that coordinates source and sink to enhance rice yield. This discovery not only contributes to a deeper molecular understanding of source-sink coordination in rice but also offers an effective strategy for rice high-yield improvement.

https://doi.org/10.1016/j.scib.2023.08.033

 

3D-printed plasmonic plastic enables large-scale optical sensor production


Peer-Reviewed Publication

CHALMERS UNIVERSITY OF TECHNOLOGY

A filament of the plasmonic plastic. 

IMAGE: A FILAMENT OF THE PLASMONIC PLASTIC. DUE TO ITS FLEXIBILITY, THE MATERIAL CAN BE FORMED INTO ALMOST ANY SHAPE. IN THIS PARTICULAR EXAMPLE, THE FILAMENT IS INTENDED FOR USE IN 3D PRINTERS. view more 

CREDIT: CHALMERS/MALIN ARNESSON




In a multi-year project, researchers at Chalmers University of Technology in Sweden have developed plasmonic plastic – a type of composite material with unique optical properties that can be 3D-printed. This research has now resulted in 3D-printed optical hydrogen sensors that could play an important role in the transition to green energy and industry.

Interest in plasmonic metal nanoparticles and their many different applications has grown rapidly, developing across a broad spectrum over the past two decades. What makes these particles so special is their ability to interact strongly with light. This makes them useful for a wide range of applications: as optical components for medical sensors and treatments, in photocatalysis to control chemical processes, and in various types of gas sensors.

Plasmonic plastic

For six years, Chalmers researchers Christoph Langhammer, Christian Müller, Kasper Moth-Poulsen, Paul Erhart and Anders Hellman and their research teams collaborated in a research project on plasmonic plastic. At the time the project began, plasmonic metal nanoparticles were being used primarily on flat surfaces and required production in advanced cleanroom laboratories. The researchers’ starting point was to ask: what if we could produce large volumes of plasmonic metal nanoparticles in a sustainable way that would make it possible to manufacture three-dimensional plasmonic objects? This is where the plastic came into the picture. The properties of plastic materials mean that they can be shaped into almost any form, are cost-effective, have upscaling potential, and can be 3D-printed.

And it worked. The project resulted in the development of new materials consisting of a mix (or composite) of a polymer and colloidal, plasmonically active, metal nanoparticles. With these materials, you can 3D-print objects of anything from a fraction of a gram up to several kilograms in weight. Some of the most important research results from the entire project have now been summarised in an article in the scientific journal Accounts of Chemical Research.

3D-printed hydrogen sensors

Plasmonic sensors that can detect hydrogen are the target application for this type of plastic composite material that the researchers chose to focus on in their project. In doing so, they have pioneered an entirely new approach in the field of optical sensors based on plasmons, namely being able to 3D-print these sensors.

“Different types of sensors are needed to speed up development in medicine, or the use of hydrogen as an alternative carbon-free fuel. The interplay between the polymer and nanoparticles is the key factor when these sensors are fabricated from plasmonic plastic. In sensor applications, this type of plastic not only enables additive manufacturing (3D printing), as well as scalability in the material manufacturing process, but has the additional important function of filtering out all molecules except the smallest ones – in our application, these are the hydrogen molecules we want to detect. This prevents the sensor from deactivating over time,” says Christoph Langhammer, professor at the Department of Physics, who led the project.

“The sensor is designed so that the metal nanoparticles change colour when they come in contact with hydrogen, because they absorb the gas like a sponge. The colour shift in turn alerts you immediately if the levels get too high, which is essential when you are dealing with hydrogen gas. At too high levels, it becomes flammable when mixed with air,” says Christoph Langhammer.

Many applications possible

While a reduction in the use of plastics is desirable in general, there are numerous advanced engineering applications that are only possible thanks to the unique properties of plastics.  Plasmonic plastics may now make it possible to exploit the versatile toolbox of polymer technology for designing novel gas sensors, or applications in health and wearable technologies as other examples. It may even inspire artists and fashion designers due to its appealing and tuneable colours.

“We have shown that the production of the material can be scaled up, that it is based on environment-friendly and resource-efficient synthesis methods for creating the nanoparticles, and is easy to implement. Within the project, we chose to apply the plasmonic plastic to hydrogen sensors, but in reality only our imagination is the limit for what it can be used for,” says Christoph Langhammer.

 

How plasmonic plastic works

  • Plasmonic plastic consists of a polymer, such as amorphous Teflon or PMMA (plexiglass), and colloidal nanoparticles of a metal that are homogenously distributed inside the polymer. At the nanoscale, the metal particles acquire useful properties such as the ability to interact strongly with light. The effect of this is called plasmons. The nanoparticles can then change colour if there is a change in their surroundings, or if they change themselves, for example through a chemical reaction, or by absorbing hydrogen.
  • By dispersing the nanoparticles in the polymer, they are protected from the surroundings because larger molecules are not as capable of moving through the polymer as hydrogen molecules, which are extremely small. The polymer acts as molecular filter. This means that a plasmonic plastic hydrogen sensor can be used in more demanding environments, and will age less. The polymer also makes it possible to easily create three-dimensional objects of vastly different sizes that have these interesting plasmonic properties.
  • This unique interaction between the polymer, nanoparticles and light can be used to achieve customized effects, potentially in a wide range of products. Different types of polymers and metals contribute different properties to the composite material, which can be tailored to the particular application.

 

More about the research

The research project “Plastic Plasmonics” received SEK 28.9 million in funding from the Swedish Foundation for Strategic Research and was concluded in the summer of 2022.

The article Bulk-Processed Plasmonic Plastic Nanocomposite Materials for Optical Hydrogen Detection, published in Accounts of Chemical Research on 4 July 2023, reports on the research which, between 2017 and 2022, was described in nearly 40 different publications.

The article’s authors are Iwan Darmadi, Ida Östergren, Sarah Lerch, Anja Lund, Kasper Moth-Poulsen, Christian Müller and Christoph Langhammer. The authors are active at the Department of Physics and the Department of Chemistry and Chemical Engineering at Chalmers University of Technology in Sweden. Researchers Anders Hellman and Paul Erhart, both of the Department of Physics, and their research teams, also contributed to the project.

In addition to his work at Chalmers, Kasper Moth-Poulsen is also active at the Institute of Materials Science of Barcelona, the Catalan Institution for Research and Advanced Studies (ICREA) and the Department of Chemical Engineering at the Universitat Politècnica de Catalunya.

 

A 3D-printed sensing element made from plasmonic plastic for use in an optical hydrogen sensor. This particular element contains nanoparticles of the metal palladium, which gives it its grey colour.

CREDIT

Chalmers/Malin Arnesson

A 3D-printed model of West-Sweden’s landmark, Vinga Lighthouse. The colour of the material is determined by the metal used for the nanoparticles in the plasmonic plastic, as well as their shape and size.

CREDIT

Chalmers/Malin Arnesson