“It has long been understood that snakes are members of a lineage of four-legged vertebrates that, as a result of evolutionary specializations, lost their limbs,” said Caldwell, lead author of the study and professor in the departments of biological sciences and earth and atmospheric sciences.

“Somewhere in the fossil record of ancient snakes is an ancestral form that still had four legs. It has thus long been predicted that a snake with four legs would be found as a fossil.”

Missing link discovered?

In a paper published in the journal Sciencein 2015, a team of researchers reported the discovery of what was believed to be an example of the first known four-legged snake fossil, an animal they named Tetrapodophis amplectus.

“If correctly interpreted based on the preserved anatomy, this would be a very important discovery,” said Caldwell.

Caldwell explained that the new study of Tetrapodophis revealed a number of mischaracterizations of the anatomy and morphology of the specimen — traits that initially seemed to be shared most closely with snakes, suggesting this might be the long-sought-after snake with four legs.

“There are many evolutionary questions that could be answered by finding a four-legged snake fossil, but only if it is the real deal. The major conclusion of our team is that Tetrapodophis amplectus is not in fact a snake and was misclassified,” said Caldwell. “Rather, all aspects of its anatomy are consistent with the anatomy observed in a group of extinct marine lizards from the Cretaceous period known as dolichosaurs.”

The clues to this conclusion, Caldwell noted, were hiding in the rock the fossil was extracted from.

“When the rock containing the specimen was split and it was discovered, the skeleton and skull ended up on opposite sides of the slab, with a natural mould preserving the shape of each on the opposite side,” said Caldwell. “The original study only described the skull and overlooked the natural mould, which preserved several features that make it clear that Tetrapodophis did not have the skull of a snake — not even of a primitive one.”

A controversial specimen

Although Tetrapodophis may not be the snake with four legs that paleontologists prize, it still has much to teach us, said study coauthor Tiago Simões, a former U of A PhD student, Harvard post- doctoral fellow and Brazilian paleontologist, who pointed out some of the features that make it unique.

“One of the greatest challenges of studying Tetrapodophis is that it is one of the smallest fossil squamates ever found,” said Simões. “It is comparable to the smallest squamates alive today that also have reduced limbs.”

An additional challenge to studying the Tetrapodophis is access to the specimen itself.

“There were no appropriate permits for the specimen’s original removal from Brazil and, since its original publication, it has been housed in a private collection with limited access to researchers. The situation was met with a large backlash from the scientific community,” said Simões.

“In our redescription of Tetrapodophis, we lay out the important legal status of the specimen and emphasize the necessity of its repatriation to Brazil, in accordance not only with Brazilian legislation but also international treaties and the increasing international effort to reduce the impact of colonialist practices in science.”

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Much hope is being pinned on the potential of gene editing using the CRISPR (gene scissors) method as a crucial part in the precision medicine of the future. However, before the method can become hospital routine, several hurdles need to be overcome.

One of these challenges is associated with how cells behave when subjected to DNA damage, which CRISPR gene editing causes in a controlled fashion. Damage to cells activates the protein p53, which acts as the cell’s “first aid” response to DNA damage.

It is already known that the technique is less effective when p53 is active; at the same time, however, a lack of p53 can allow cells to start growing uncontrollably and become cancerous. In over half of all cancers the gene for p53 is mutated and thus unable to protect against uncontrolled cell division. It is therefore important to avoid the enrichment (accumulation) of such mutated cells.

Researchers at Karolinska Institutet have now shown that cells with inactivating mutations of the p53 gene gain a survival advantage when subjected to CRISPR and can thus accumulate in a mixed cell population.

The researchers have also identified a network of linked genes with mutations that have a similar effect to p53 mutations, and shown that the transient inhibition of p53 is a possible pharmaceutical strategy for preventing the enrichment of cells with such mutations.

“It can seem contradictory to inhibit p53 in a CRISPR context,” says the study’s first author Long Jiang, doctoral student at the Department of Medicine, Karolinska Institutet (Solna). “However, some of the literature supports the idea that p53 inhibition can make CRISPR more effective. In our study we show that this can also counteract the enrichment of cells with mutations in p53 and a group of associated genes.”

The research has a contributory potential to the future clinical implementation of CRISPR in having identified a network of possible candidate genes that should be carefully controlled for mutations when cells are subjected to the CRISPR technique. Another possible conclusion is that the transient inhibition of p53 could prove a strategy for reducing the enrichment of mutated cells.

The researchers have also studied the DNA-damage response as a possible marker in the development of more precise guide RNA sequences, which are used to show CRISPR where a DNA sequence is to be altered.

“We believe that the up-regulation of genes involved in the DNA damage response can be a sensitive marker for how much unspecific (‘off-target’) activity a guide RNA has, and can thus help in the selection of ‘safer’ guide RNAs,” says the study’s last author Fredrik Wermeling, researcher at the Department of Medicine, Karolinska Institutet (Solna).

The study is largely based on CRISPR, CRISPR screening experiments on isolated cells and analyses of the DepMap database.

The next step of the research is to understand how relevant the described mechanisms are.

“In cell cultures, we see a rapid and pronounced enrichment of cells with p53 mutations when we subject the cells to CRISPR, provided, however, that cells with mutations are there from the start,” says Dr. Wermeling. “So we can show that the mechanism exists and factors that affect it, but don’t currently know at what level this is a genuine problem, and that’s something we want to explore further in more clinic-centered tests.”

The study was conducted in collaboration with David P. Lane’s group (MTC) and financed by the Swedish Research Council, the Swedish Cancer Society, Karolinska Institutet, the Magnus Bergvall Foundation, the China Scholarship Council and the Nanyang Technological University-Karolinska Institutet Joint PhD Program (VSI).

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Scientists used data on more than 9,000 soil samples from around the world, and found that carbon storage “declines strongly” as average temperatures increase.

This is an example of a “positive feedback,” where global warming causes more carbon to be released into the atmosphere, further accelerating climate change.

Importantly, the amount of carbon that could be released depends on the soil type, with coarse-textured (low-clay) soils losing three times as much carbon as fine-textured (clay-rich) soils.

The researchers, from the University of Exeter and Stockholm University, say their findings help to identify vulnerable carbon stocks and provide an opportunity to improve Earth System Models (ESMs) that simulate future climate change.

“Because there is more carbon stored in soils than there is in the atmosphere and all the trees on the planet combined, releasing even a small percentage could have a significant impact on our climate,” said Professor Iain Hartley of Exeter’s College of Life and Environmental Sciences.

“Our analysis identified the carbon stores in coarse-textured soils at high-latitudes (far from the Equator) as likely to be the most vulnerable to climate change.

“Such stores, therefore, may require particular attention given the high rates of warming taking place in cooler regions.

“In contrast, we found carbon stores in fine-textured soils in tropical areas to be less vulnerable to climate warming.”

The data on the 9,300 soil profiles came from the World Soil Information database, with the study focusing on the top 50cm of soil.

By comparing carbon storage in places with different average temperatures, the researchers estimated the likely impact of global warming.

For every 10°C of increase in temperature, average carbon storage (across all soils) fell by more than 25%.

“Even bleak forecasts do not anticipate this level of warming, but we used this scale to give us confidence that the effects we observed were caused by temperature rather than other variables,” Professor Hartley said.

“Our results make it clear that, as temperatures rise, more and more carbon is release from soil.

“It’s important to note that our study did not examine the timescales involved, and further research is needed to investigate how much carbon could be released this century.”

The researchers found that their results could not be represented by an established ESM.

“This suggests that there is an opportunity to use the patterns we have observed to improve how models represent soils, and further reduce uncertainty in their projections,” Professor Hartley said.

The differences in carbon storage based on soil texture occur because finer soils provide more mineral surface area for carbon-based organic material to bond to, reducing the ability of microbes to access and decompose it.

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A new study from the University of Illinois examines the dynamics of long-term relationships through spatial proximity. The researchers find that when partners are close to each other, their heart rates synchronize in complex patterns of interaction.

“Relationship researchers typically ask people how they’re doing and assume they can recall properly and give meaningful answers. But as couples age and have been together for a long time, they laugh when we ask them how satisfied or how committed they are. When they have been married for 30 or 40 years, they feel that indicates commitment in itself,” says Brian Ogolsky, associate professor in the Department of Human Development and Family Studies at the U of I and lead author on the study.

“We were looking for more objective ways to measure relationship dynamics, and we know that being around other people has psychological benefits. So, physical proximity seemed liked a strong candidate.”

But just being close to another person isn’t always beneficial; it depends on the nature of the interaction, Ogolsky points out. Closeness in the context of a conflict is very different from closeness in the context of a loving interaction. Similarly, changes in heart rate can be positive or negative.

“We’re not focusing on cause and effect, but on co-regulation, which happens when heart rates move in a synchronous pattern. That is, when the partners are close, their heart rate patterns indicate an interaction that is collectively meaningful in some way.”

The study included 10 heterosexual, married couples, ages 64 to 88, who had been in their relationships from 14 to 65 years. The researchers followed the couples for two weeks, continuously tracking their heart rates and their proximity to each other when at home.

Participants wore a Fitbit measuring their heart rate. They also wore a small proximity-sensing device. The researchers installed sensors in the home that allowed them to monitor the devices and observe in real time how physically close the spouses were to each other. They could then correlate all three measures — each partner’s heart rate and the couple’s proximity — in real time.

The researchers called the couples in the morning to remind them to put on the Fitbit and tracking device, and again in the evening for a survey about their health and well-being as well as their relationship dynamics throughout the day.

“Our first step was to see if heart rate and proximity are correlated over time. We looked at the husband’s heart rate with proximity, the wife’s heart rate with proximity, and the two heart rates with each other,” Ogolsky says.

“We also wanted to know if all three time-series worked together to give us unique information. Can we use any of them to predict the others? And the answer is yes. All three time-series need to be included for us to be able to predict any one of them well.”

The findings indicated a lead-lag relationship in heart rate synchronization, where one partner leads and the other follows. Sometimes the wife’s heart rate would lead the change and other times the husband’s heart rate would change and the wife’s would follow.

“This suggests a delicate balance. When one partner triggers the other partner, they start a unique couple-level dance that affects their physiology and their patterns throughout the day,” Ogolsky states.

Because of the small number of participants, the study did not include comparisons between couples. But even within the couples, no clear patterns emerged.

“We found each day is a unique context that changes depending on circumstances. Couple interactions, their attitudes, behaviors, whether they’re close to each other or far away, change all the time. Even across 14 days, couples are not consistent enough in these kinds of objective patterns to allow us to make any couple-level conclusions. We can make only make day-level predictions.”

Ogolsky notes this finding is an important contribution to relationship research, which usually relies on drawing conclusions across couples.

“If we really want to understand the unique patterns of interaction that happen within couples, we need to start focusing our attention on micro processes; the small interaction patterns that accumulate over a day. Those tell us about the nature of how couples’ interactions play out from moment to moment.”

This work was supported by the Center for Social and Behavioral Science and National Institute of Food and Agriculture grant number 793-349.

But the most important and fundamental function of life on Earth — photosynthesis — has not been relevant with regards to plant selection or breeding until now, an age when greenhouse gas emissions from human activities threaten our planet. With new technologies at hand, scientists around the world are now working to understand the internal processes of plants that drive photosynthesis.

In a new study published in the scientific journal PNAS, researchers from the University of Copenhagen’s Department of Plant and Environmental Sciences have just discovered that a group of proteins in plant leaf cells, called CURT1, plays a much more important role in photosynthesis than once thought.

“We have discovered that CURT1 proteins control a plant’s development of green leaves already from the seed stage. Thus, the proteins have a major influence on how effectively photosynthesis is established,” explains Associate Professor Mathias Pribil, the study’s lead author.

Proteins that kickstart photosynthesis

CURT1 proteins were previously believed to play a more modest role and only be present in fully-developed leaves. But using state-of-the-art Imaging techniques (photography and computer equipment), the researchers zoomed 30,000x in on the growth of a series of experimental thale cress (Arabidopsis) plants. This allowed them to study the plants at a molecular level. The researchers could see that CURT1 proteins were present from the earliest stages of their plants’ lives.

“Emerging from the soil is a critical moment for the plant, as it is struck by sunlight and rapidly needs to get photosynthesis going to survive. Here we can see that CURT1 proteins coordinate processes that set photosynthesis in motion and allow the plant to survive, something we didn’t know before,” explains Mathias Pribil.

Photosynthesis takes place in chloroplasts, 0.005 mm long elliptical bodies in plant cells that are a kind of organ within the cells of a plant leaf. Within each chloroplast, a membrane harbours proteins and the other functions that make photosynthesis possible.

“CURT1 proteins control the shape of this membrane, making it easier for other proteins in a plant cell to move around and perform important tasks surrounding photosynthesis, depending on how the environment around the plant changes. This could be to repair light harvesting protein complexes when the sunlight is intense or to turn up a chloroplast’s ability to harvest light energy when sunlight is weak,” explains Pribil.

Improved CO₂ uptake in the future

The new finding provides deeper insight into Earth’s most important biochemical reaction. Indeed, without plants, neither animals nor humans would exist on our planet. Thus far, the result only applies to the thale cress plant, but Pribil would be “very surprised” if the importance of CURT1 proteins for photosynthesis didn’t extend to other plants as well.

“This is an important step on the way to understanding all of the components that control photosynthesis. The question is whether we can use this new knowledge to improve the CURT1 protein complex in plants in general, so as to optimize photosynthesis,” says Mathias Pribil, who adds:

“Much of our research revolves around making photosynthesis more efficient so that plants can absorb more CO₂. Just as we have selected and bred the best crops throughout the history of agriculture, it is now about helping nature become the best possible CO₂ absorber,” says Mathias Pribil.

Photosynthesis Facts:

• Photosynthesis is one of the most important biological processes on Earth, as it produces most of the oxygen in our atmosphere, upon which nearly all life depends.
• Photosynthesis takes place in green plants, algae and some bacteria, when solar energy converts carbon dioxide and water into oxygen and organic matter in the form of glucose.
• Glucose is then converted into nutrients and used by the plants themselves and animals Source: Den Store Dansk

CURT1 protein facts:

• CURT1 is a protein group which coordinates structural processes of the internal chloroplast membrane that makes photosynthesis function more efficiently.
• It was once thought that this protein group was only present in plants with mature leaves, and that the protein played a less important role. Scientists now know that the protein group is central to managing photosynthesis.
• The protein group also helps plant leaves increase or decrease their light-harvesting ability depending upon sunlight strength.
• Plants with a misbalanced CURT1 protein content — whether too many or too few — had a higher mortality rate and generally poorer growth.

In southeastern Iberia, one of the most outstanding archaeological entities of the European Bronze Age emerged around 2,200 BCE. This so-called ‘El Argar’ culture, one of the first state-level societies on the European continent, was characterised by large, central hilltop settlements, distinct pottery, specialized weapons and bronze, silver and gold artefacts, alongside an intra-murial burial rite. A new study explores the relation between dynamic shifts at population scale and the major social and political changes of the third and second millennia BCE by analysing the genomes of 136 ancient Iberians, ranging from 3,000 to 1,500 BCE.

Genetic turnover and melting pot

Including published genomes from Iberia, the new study encompasses data from nearly 300 ancient individuals and focuses specifically on the Copper to Bronze Age transition around 2,200 BCE.

“While we knew that the so-called ‘steppe’-related ancestry, which had spread across Europe during the third millennium BCE, eventually reached the northern Iberian Peninsula around 2,400 BCE, we were surprised to see that all prehistoric individuals from the El Argar period carried a portion of this ancestry, while the Chalcolithic individuals did not,” says Max Planck researcher Wolfgang Haak, senior author and principal investigator of the study.

The genomic data reveals some of the processes underlying this genetic shift. While the bulk of the genome shows that Bronze Age individuals are a mix of local Iberian Chalcolithic ancestry and a smaller part of incoming ancestry from the European mainland, the paternally inherited Y chromosome lineages show a complete turnover, linked to the movement of steppe-related ancestry that is also visible in other parts of Europe.

The rich new data from the El Argar sites also show that these two components do not fully account for the genetic make-up of the early Bronze Age societies.

“We also found signals of ancestry that we traced to the central and eastern Mediterranean and western Asia. We cannot say exactly whether these influences arrived at the same time as the steppe-related ancestry, but it shows that it formed an integrative part of the rising El Argar societies, attesting to continued contacts to these regions,” adds Vanessa Villalba-Mouco, postdoctoral researcher at the Max Planck Institute and Instituto de Biología Evolutiva.

Social implications

“Whether the genetic shift was brought about by migrating groups from North and Central Iberia or by climatic deteriorations that affected the eastern Mediterranean around 2,200 BCE is the million-dollar question,” says co-PI and senior author Prof Roberto Risch from the Universitat Autònoma de Barcelona. “It would be foolish to think that it can all be explained by a simple, one-factor model. While the temporal coincidence is striking, it is likely that many factors played a role.”

One of these factors could be pandemics, such as an early form of the Plague, which has been attested to in other regions of Europe around the time. While not found directly among the tested individuals in southern Iberia, it could be a cause or driver for the movement or disappearance of other groups in the region.

“In any case, we can now conclude that the population movement starting in the eastern European steppe zones around 3,000 BCE was not a single migratory event, but required over four centuries to reach the Iberian Peninsula and another 200 years to appear in present-day Murcia and Alicante,” adds Risch.

The archaeological record of the El Argar group shows a clear break with previous Chalcolithic traditions. Burial rites, for example, changed from communal to single and double burials within the building complexes. Elite burials also indicate the formation of strong social hierarchies. Testing for biological relatedness, the researchers found that males are on average more closely related to other people at the site, indicating that the group was likely patrilineally structured. Such a social organization could explain the stark reduction of the Y-lineage diversity.

“We observe similar patterns of social organisation and increasing stratification also in other parts of Early Bronze Age Europe, in fact broadly around the same time and with similar characteristics of early state-like formations. This suggests a structured restart or resetting following some form of crisis or unstable, highly dynamic times,” summarises Haak.