Nose shape gene inherited from Neanderthals

Humans inherited genetic material from Neanderthals that affects the shape of our noses, finds a new study led by UCL researchers.

The new Communications Biology study finds that a particular gene, which leads to a taller nose (from top to bottom), may have been the product of natural selection as ancient humans adapted to colder climates after leaving Africa.

Co-corresponding author Dr Kaustubh Adhikari (UCL Genetics, Evolution & Environment and The Open University) said: "In the last 15 years, since the Neanderthal genome has been sequenced, we have been able to learn that our own ancestors apparently interbred with Neanderthals, leaving us with little bits of their DNA.

"Here, we find that some DNA inherited from Neanderthals influences the shape of our faces. This could have been helpful to our ancestors, as it has been passed down for thousands of generations."

The study used data from more than 6,000 volunteers across Latin America, of mixed European, Native American and African ancestry, who are part of the UCL-led CANDELA study, which recruited from Brazil, Colombia, Chile, Mexico and Peru. The researchers compared genetic information from the participants to photographs of their faces -- specifically looking at distances between points on their faces, such as the tip of the nose or the edge of the lips -- to see how different facial traits were associated with the presence of different genetic markers.

The researchers newly identified 33 genome regions associated with face shape, 26 of which they were able to replicate in comparisons with data from other ethnicities using participants in east Asia, Europe, or Africa.

In one genome region in particular, called ATF3, the researchers found that many people in their study with Native American ancestry (as well as others with east Asian ancestry from another cohort) had genetic material in this gene that was inherited from the Neanderthals, contributing to increased nasal height. They also found that this gene region has signs of natural selection, suggesting that it conferred an advantage for those carrying the genetic material.

First author Dr Qing Li (Fudan University) said: "It has long been speculated that the shape of our noses is determined by natural selection; as our noses can help us to regulate the temperature and humidity of the air we breathe in, different shaped noses may be better suited to different climates that our ancestors lived in. The gene we have identified here may have been inherited from Neanderthals to help humans adapt to colder climates as our ancestors moved out of Africa."

Co-corresponding author Professor Andres Ruiz-Linares (Fudan University, UCL Genetics, Evolution & Environment, and Aix-Marseille University) added: "Most genetic studies of human diversity have investigated the genes of Europeans; our study's diverse sample of Latin American participants broadens the reach of genetic study findings, helping us to better understand the genetics of all humans."

The finding is the second discovery of DNA from archaic humans, distinct from Homo sapiens, affecting our face shape. The same team discovered in a 2021 paper that a gene influencing lip shape was inherited from the ancient Denisovans.

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Plant roots change shape and branch out for water

Researchers have discovered how plant roots adapt their shape to maximise their uptake of water, pausing branching when they lose contact with water and only resuming once they reconnect with moisture, ensuring they can survive even in the driest conditions.

Plant scientists from the University of Nottingham have discovered a novel water sensing mechanism that they have called 'Hydro-Signalling', which shows how hormone movement is linked with water fluxes. The findings have been published today in Science.

Water is the rate-limiting molecule for life on earth. The devastating impact of climate change is enhancing the effects of water stress on global agriculture. Climate change is causing rainfall patterns to become more erratic, impacting rain-fed crops in particular.

Roots play a critical role to reduce the impact of water stress on plants by adapting their shape (such as branching or growing deeper) to secure more water. Discovering how plant roots sense and adapt to water stress is vital importance for helping 'future proof' crops to enhance their climate resilience.

Using X-ray micro-CT imaging researchers were able to reveal that roots alter their shape in response to external moisture availability by linking the movement of water with plant hormone signals that control root branching.

The study provides critical information about the key genes and processes controlling root branching in response to limited water availability, helping scientists design novel approaches to manipulate root architecture to enhance water capture and yield in crops.

Dr. Poonam Mehra, postdoctoral fellow, from the School of Biosciences is one of the lead authors and explains: "When roots are in contact with moisture, a key hormone signal (auxin) moves inwards with water, triggering new root branches. However, when roots lose contact with moisture, they rely on internal water sources that mobilises another hormone signal (ABA) outwards, which acts to block the inwards movement of the branching signal. This simple, yet elegant mechanism enables plant roots to fine tune their shape to local conditions and optimize foraging."

Professor Malcolm Bennett, co-lead on the research adds: "Our plant research is vitally important for understanding how we can futureproof crops and find ways to ensure successful crop yields even in the most challenging climates. We are already experiencing a hotter climate and designing plants that can still access water in these conditions is vital and this research is an all important step in understanding how to do this." He continued: "These new discoveries were only possible because of the cutting-edge tools and collaborative approaches of the authors, which involved an international team of scientists based in the UK, Belgium, Sweden, USA and Israel.'"

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How we retrieve our knowledge about the world

To understand the world, we arrange individual objects, people, and events into different categories or concepts. Concepts such as 'the telephone' consist primarily of visible features, i.e. shape and color, and sounds, such as ringing. In addition, there are actions, i.e. how we use a telephone.

However, the concept of telephone does not only arise in the brain when we have a telephone in front of us. It also appears when the term is merely mentioned. If we read the word "telephone," our brain also calls up the concept of telephone. The same regions in the brain are activated that would be activated if we actually saw, heard, or used a telephone. The brain thus seems to simulate the characteristics of a telephone when its name alone is mentioned.

Until now, however, it was unclear, depending on the situation, whether the entire concept of a telephone is called up or only individual features such as sounds or actions and whether only the brain areas that process the respective feature become active. So, when we think of a telephone, do we always think of all its features or only the part that is needed at the moment? Do we retrieve our sound knowledge when a phone rings, but our action knowledge when we use it?

Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig have now found the answer: It depends on the situation. If, for example, the study participants thought of the sounds associated with the word "telephone," the corresponding auditory areas in the cerebral cortex were activated, which are also activated during actual hearing. When thinking about using a telephone, the somatomotor areas that underlie the involved movements came into action.

In addition to these sensory-dependent, so-called modality-specific areas, it was found that there are areas that process both sounds and actions together. One of these so-called multimodal areas is the left inferior parietal lobule (IPL). It became active when both features were requested.

The researchers also found out that, in addition to characteristics based on sensory impressions and actions, there must be other criteria by which we understand and classify terms. This became apparent when the participants were only asked to distinguish between real and invented words. Here, a region that was not active for actions or sounds kicked in: the so-called anterior temporal lobe (ATL). The ATL therefore seems to process concepts abstractly or "amodally," completely detached from sensory impressions.

From these findings, the scientists finally developed a hierarchical model to reflect how conceptual knowledge is represented in the human brain. According to this model, information is passed on from one hierarchical level to the next and at the same time becomes more abstract with each step. On the lowest level, therefore, are the modality-specific areas that process individual sensory impressions or actions. These transmit their information to the multimodal regions such as the IPL, which process several linked perceptions simultaneously, such as sounds and actions. The amodal ATL, which represents features detached from sensory impressions, operates at the highest level. The more abstract a feature, the higher the level at which it is processed and the further it is removed from actual sensory impressions.

"We thus show that our concepts of things, people, and events are composed, on the one hand, of the sensory impressions and actions associated with them and, on the other hand, of abstract symbol-like features," explains Philipp Kuhnke, lead author of the study, which was published in the journal Cerebral Cortex. "Which features are activated depends strongly on the respective situation or task" added Kuhnke.

In a follow-up study in Cerebral Cortex, the researchers also found that modality-specific and multimodal regions work together in a situation-dependent manner when we retrieve conceptual features. The multimodal IPL interacted with auditory areas when retrieving sounds, and with somatomotor areas when retrieving actions. This showed that the interaction between modality-specific and multimodal regions determined the behavior of the study participants. The more these regions worked together, the more strongly the participants associated words with actions and sounds.

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Triangular-shaped spikes key to coronavirus transmission, finds new study

COVID-19 needs no introduction. Last year, the disease, which is caused by the virus SARS-CoV-2, reached every continent across the globe. By the end of March 2021, there had been an estimated 128 million cases recorded with almost three million of these being fatal. As scientists' race to develop vaccines and politicians coordinate their distribution, fundamental research on what makes this virus so successful is also being carried out.

Within the Mathematics, Mechanics, and Materials Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), postdoctoral researcher, Dr. Vikash Chaurasia, and Professor Eliot Fried have been using energy minimization techniques to look at charged proteins on biological particles. Previously they researched cholesterol molecules but when the pandemic hit, they realized that with the methods they had developed could be applied to the new virus. They collaborated with researchers Mona Kanso and Professor Jeffrey Giacomin, from Queen's University in Canada, to take a close look at SARS-CoV-2 and see how the shape of the virus' 'spikes' (which are officially called peplomers) aid its success at spreading so prolifically. Their study was recently published in Physics of Fluids.

"When one envisions a single coronavirus particle, it is common to think of a sphere with many spikes or smaller spheres distributed across its surface," said Dr. Chaurasia. "This is the way the virus was originally modeled. But this model is a rough sketch and over the last year, we've come to learn much more about what the virus looks like."

Instead, Dr. Chaurasia pointed out, the 'spikes' of the coronavirus particle are actually shaped like three small spheres stacked together to form a triangular shape. This is an important consideration because the shape of a viral particle can influence its ability to disperse.

To understand this, imagine a ball moving through space. The ball will follow a curve but, as it does this, it will also rotate. The speed at which the ball rotates is called its rotational diffusivity. A particle of SARS-CoV-2 moves in a similar way to this ball although its suspended in fluid (specifically, tiny droplets of saliva). The rotational diffusivity of the particle impacts how well it can align with and attach itself to objects (such as a person's tissues or cells) and this has been key in its ability to successfully spread from person to person so quickly. A higher rotational diffusivity will mean that the particle shakes and jitters as it follows a trajectory -- and thus may have difficulty attaching to objects or efficiently bouncing off an object to continue to move through the air. Whereas a lower rotational diffusivity has the opposite effect.

Another consideration was the charge of each spike. The researchers assumed that each is equally charged. The same charges always repel each other so if there are only two spikes on a particle and they have equal charges, they'll be situated at either pole (as far away from each other as possible). As more equally charged spikes are added, they become evenly distributed across the surface of the sphere. This provided the researchers with a geometrical arrangement from which they could calculate the rotational diffusivity.

Previously, the researchers looked at a viral particle with 74 spikes. For this new study, they used the same particle but switched out the single-bead spikes for the three-bead triangles. When they did this, the rotational diffusivity of the particle was found to decrease by 39%. Moreover, this trend was found to continue with the addition of more spikes.

This was an important finding -- having a lower rotational diffusivity means that the virus particles can better align and attach themselves to objects and people. Thus, this study suggests that the triangular shaped spikes have contributed to the success of SARS-CoV-2.

"We know it's more complicated than this," explained Dr. Chaurasia. "The spikes might not be equally charged. Or they might be flexible and able to twist themselves. Also, the 'body' of the particle might not be a sphere. So, we plan to do more research in this area."

An additional interesting feature of this research is its connection to a question asked more than a century ago by physicist J. J. Thomson, who explored how a set number of charges will be distributed across a sphere.

"I find it fascinating that a problem considered more than 100 years ago has such relevance for the situation we're in today," said Professor Eliot Fried. "Although this question was first posed primarily from a standpoint of curiosity and intellectual interest, it has turned out to be applicable in unexpected ways. This shows why we mustn't lose site of the importance of fundamental research."

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