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Tag: University of Würzburg

  • Venus flytrap heat sensor warns of fire

    Venus flytrap heat sensor warns of fire

    Newswise — The Venus flytrap can survive in the nutrient-poor swamps of North and South Carolina because it compensates for the lack of nitrogen, phosphate and minerals by catching and eating small animals. It hunts with snap traps that have sensory hairs on them. If an insect touches these hairs two times, the traps shut and digests the prey.

    In its location in the swamp, the carnivorous plant is often not visible because it is overgrown by grass. In summer, the grass dries up. Then it can catch fire from the frequent lightning storms typical of North Carolina – a dangerous situation for the Venus flytrap.

    How does the plant protect its vital snap traps and sensory hairs from fire? Biophysicists Professor Rainer Hedrich and Dr. Shouguang Huang from Julius-Maximilians-University (JMU) Würzburg in Bavaria, Germany, have found out: The Venus flytrap uses special heat receptors in the sensory hairs for this purpose, as the researchers report in the journal Current Biology.

    Carolina bushfire imitated in Würzburg

    “To find out how the flytrap behaves when burning a covering of dry grass, we transplanted plants with open snap traps from the greenhouse to the open field in the JMU Botanical Garden and covered them with hay,” says Rainer Hedrich. “Then we set fire to the hay at one end and forced it to spread to the other end with a fan”.

    After the fire, the plants had closed all the traps. Some traps showed no damage, others appeared to be burnt. After a few days, all undamaged traps were open again and working – they snapped after touching their sensory hairs.

    Hot air makes the fly traps snap

    “We had only recently elucidated the stimulus-response chain during trap closure after wounding. Now the question arose whether the traps might already react to the heat wave in the run-up to a fire,” says Hedrich.

    The JMU researchers were correct in their assumption: a hot air blower directed at the trap was sufficient to cause the trap to close. Next, the scientists conducted heat experiments under controlled laboratory conditions.

    Heat sensor activates at 37 and 55 degrees Celsius

    The catching organ of the Venus flytrap consists of two leaf halves. Dr. Shouguang Huang brought the outside of one half of the trap into contact with a Peltier element – with this electrothermal transducer, he was able to selectively set different temperatures on the trap through controlled current supply.

    He found that when a local leaf temperature of 37 degrees Celsius was exceeded, the heated area of the trap produced an electrical impulse, an action potential that spread across both halves of the trap. “When the temperature increased further to 55 degrees Celsius, a second action potential was triggered and the trap snapped shut,” Shouguang said.

    But the trap’s reaction at 37 and 55 degrees Celsius only kicked in when temperatures increased abruptly, as in a rapid heat wave. If the temperature rose only slowly, as on hot summer days, the traps did not react.

    “In contrast to humans, the heat sensor of the carnivorous plant does not jump when the body temperature is exceeded, but it reacts to the speed of the temperature change,” says Hedrich.

    By measuring the temperature rise on its surface and closing its traps in a fraction of a second, the flytrap’s sensory hairs remain protected from burns. The damp marshy ground further protects them from excessive heat and burns. This allows it to continue hunting for animal food after a fire.

    The heat sensor is located in the sensory hairs

    Each half of the trap has three sensory hairs that are highly sensitive to touch and generate action potentials. The action potentials are generated at the base of the hairs. There, ion channels that get activated by touch allow calcium to flow into the cells. This calcium signal is the trigger and at the same time an integral part of an action potential. Heat jumps cause the same calcium-dependent electrical events in the sensory hairs as touch.

    “To track the calcium signal, we used flytraps that carry a genetically encoded calcium sensor inside them,” Hedrich says. When the cellular calcium levels increase, this sensor begins to fluoresce. “We were quite amazed that when the heat was applied, a sensory hair glowed first,” he said. “This shows that the hairs operate as touch and heat sensors at the same time,” Hedrich concludes.

    Focus on calcium channel from the OSCA family

    “Currently, we are pursuing the hypothesis that a calcium channel is an integral part of the heat sensor, or even the sensor itself,” the researchers said. If this is true, a type of membrane-bound temperature sensor would have been discovered that is still completely unknown in plants.

    So far, research knows calcium channels from the so-called OSCA family, which can be activated mechanically and osmotically. “In the future, we want to test whether there are also OSCAs in the sensory hairs of the Venus flytrap that are switched on by the supply of thermal energy, and which of their protein areas respond to mechanics and which to heat.”

    University of Wurzburg

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  • First steps towards a more climate-friendly streaming

    First steps towards a more climate-friendly streaming

    Newswise — In recent years, video streaming has increased significantly. While every German spent an average of 42 minutes a day watching online videos on YouTube, Netflix, Facebook or other platforms in 2019, a year later it was already 55 minutes – in the group of 14- to 29-year-olds even 130 minutes.

    This is bad news for the climate, since streaming requires enormous computer capacity and thus energy, which rarely comes from renewable sources. According to a 2019 study, video streaming activity accounted for about 60 percent of global data traffic in 2018, emitting 306 million tons of CO2, which was comparable to Spain’s annual emissions.

    Study in the Journal of Consumer Policy

    How can users reduce their energy consumption? This was investigated by a team of scientists from the Julius-Maximilians-Universität Würzburg (JMU). Dr. Benedikt Seger, research associate at the Institute of Psychology at JMU, was responsible for the study. The team has now published the results in the Journal of Consumer Policy.

    “Over a period of seven weeks, we investigated how people can reduce CO2 emissions when watching videos on the Internet,” explains Seger. Seger and his team used three different approaches t o help users change their streaming habits.
    First, they informed participants about the carbon footprint of online videos and showed them ways to improve it – for example, by switching from smart TVs to laptops, selecting a lower resolution, or turning off the Autoplay function. In a second step, they set a CO2 reduction target of 20 percent for some of them. In the third step, some of the study participants received additional weekly feedback on the carbon footprint of their streaming activities and whether they had met the agreed target.

    Information is the key to success

    The results were unequivocal: “It turned out that providing information at the end of the first week already led to a drop in CO2 consumption of up to 30 percent in the following weeks,” explains Seger. In contrast, the two subsequent stimuli – the 20 percent reduction target and the weekly feedback – had no additional effect.

    Reducing the streaming duration as well as choosing lower resolutions were responsible for the decrease. “From this, we conclude that individuals can improve the carbon footprint of their digital activities if they are provided with appropriate problem and action knowledge and keep a kind of diary of their activities,” Seger says.

    The study is part of the research focus “Climate Communication, Attitude and Behavior Change” at the Institute of Psychology at the University of Würzburg. Last year, the team already published a highly regarded study, according to which references on menus to the carbon footprint of dishes persuade people to reach for the more climate-friendly alternative more often. “With the present study, we want to direct the focus of the public climate discourse more strongly than before to digital areas of life,” says the psychologist.

    Streaming platforms can also make their contribution

    However, Seger does not see the responsibility resting solely with users. Rather, in his opinion, platform providers can also make a significant contribution to energy saving, for example by switching to climate-friendly default settings. Anyone who then calls up the respective website or opens an app would, in principle, be shown the videos in a low resolution. For higher quality, users have to take action. A deactivated Autoplay function should also be part of these standard settings. Then the next movie would not start automatically and immediately after the end of one.

    “Of course, it would be even more effective to convert the data centers to renewable energies,” says Seger. However, local, national and international decision-making bodies would have to set favorable framework conditions for this.

    https://www.uni-wuerzburg.de/en/news-and-events/news/detail/news/erste-schritte-zu-klimafreundlicherem-streamen/

    University of Wurzburg

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  • Protein spheres protect the genome of cancer cells

    Protein spheres protect the genome of cancer cells

    Newswise — MYC genes and their proteins play a central role in the emergence and development of almost all cancers. They drive the uncontrolled growth and altered metabolism of tumour cells. And they help tumours hide from the immune system.

    MYC proteins also show an activity that was previously unknown – and which is now opening new doors for cancer research: They form hollow spheres that protect particularly sensitive parts of the genome. If these MYC spheres are destroyed, cancer cells will die.

    This was reported by a research team led by Martin Eilers and Elmar Wolf from the Institute of Biochemistry and Molecular Biology at Julius-Maximilians-Universität Würzburg (JMU, Bavaria, Germany) in the journal “Nature”. The researchers are convinced that their discovery is a game changer for cancer research, an important breakthrough on the way to new therapeutic strategies.

    Hollow spheres protect sensitive DNA sites

    What the researchers discovered: When cells in the lab are kept under stress conditions similar to those found in fast-growing tumour cells, the MYC proteins in the cell nucleus rearrange themselves in a dramatic way. They join together to form hollow spheres consisting of thousands of MYC proteins.

    The hollow spheres surround and protect individual, particularly sensitive sites in the genome – precisely the sites where two types of enzymes can collide: Enzymes that read DNA to synthesize RNA and enzymes that duplicate DNA. Both can be thought of as two trains travelling on only one track, on DNA.

    The hollow spheres thus prevent the two enzymes from colliding. The Würzburg team was able to confirm this observation in cancer cells. If the protective function of the protein spheres is switched off experimentally, collisions of the enzymes occur and, as a consequence, multiple breaks occur in the DNA – which ultimately kill the cancer cells.

    Search for specifically effective drugs

    “These observations revolutionize our understanding of why MYC proteins are so crucial for the growth of tumor cells,” says Martin Eilers. The new findings also raise the question of whether drugs can be developed that specifically prevent the formation of the hollow spheres.

    To drive this development forward, Eilers and Wolf have started a company. Together with JMU and partners from the pharmaceutical industry, the search for drugs that interfere with the newly discovered functions of the MYC proteins has begun.

    “The fact that investors made it possible for us to set up so quickly is certainly not an everyday occurrence,” say the JMU professors. They also consider this as a sign that they have made a discovery that is very promising.

    University of Wurzburg

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  • Gene activity in a test tube

    Gene activity in a test tube

    Newswise — Pathological processes are usually characterised by altered gene activity in the cells affected. So, gaining an accurate picture of gene activity can provide the key to the development of new, targeted therapies. Whether these therapies then work as we would want them to can also be verified by looking at genes and the processes they initiate.

    It is no wonder that research is focused on methods and techniques that provide detailed information about the genetic activity of individual cells. A research team at the University of Würzburg (JMU) has now developed a technique that is a significant improvement on the methods used to date. Scientists from the Institute for Molecular Infection Biology (IMIB) and the Helmholtz Institute for RNA-based Infection Research (HIRI) were involved. They have presented the results of their work in the current issue of the journal Nucleic Acids Research.

    Analysis of a synthetic transcriptome

    “We have developed a technique that can be used to analyse the translational landscape of a fully customisable synthetic transcriptome, in other words one outside the cell,” is how Jörg Vogel explains the central outcome of the study. Vogel heads the Institute for Molecular Infection Biology at JMU and is also the Director of HIRI as well as the principal author of the study. The new technique has been given the scientific name INRI-seq, which is short for in vitro Ribo-seq.

    A transcriptome is a collection of all the genes that are active in a cell at a given point in time. It consists of the sum of the existing mRNA – the transporters of the blueprints for proteins from the cell nucleus to the ribosomes. Ribosomes are the “protein factories” of the cell; this is where translation of the nucleotide sequence of the mRNA into the amino acid sequence of a protein takes place.

    Refinement of comparable methods

    In principle, INRI-seq is a refinement of comparable methods that pursue the same goal but provide less accurate results or have other disadvantages. For example, RNA sequencing (RNA-seq) determines the concentration of mRNA in cells, allowing conclusions to be drawn about their active genes. However, the final protein abundance does not always correlate with the respective mRNA concentrations.

    A more accurate technique is ribosome profiling (Ribo-seq). Over the past ten years, this has become one of the main methods for measuring protein synthesis directly in a transcriptome-wide manner. “While Ribo-seq has greatly advanced the study of translation-related processes, the method has not been without limitations,” says Jörg Vogel.

    Numerous limitations of Ribo-seq

    For instance, it is a major challenge to detect weakly expressed genes with Ribo-seq, preventing many genes from being recorded in common study designs. Similarly, a Ribo-seq study of microbes from important ecological habitats such as the human gut is difficult since many of them cannot be cultured in the laboratory.

    A further shortcoming, as Vogel explains, is the fact that “on the mechanistic level, Ribo-seq-based studies of molecules affecting translation, such as special antibiotics, can be hampered by cellular responses”. Since Ribo-seq is performed on living cells, it can be difficult to distinguish between direct and indirect effects on translation.

    To overcome some of these limitations, the scientists from Würzburg have developed INRI-seq for the global study of translation in a cell-free environment. INRI-seq uses a commercially available in vitro translation system combined with an in vitro-synthesised, fully customisable transcriptome that allows better control of individual mRNA levels. “With INRI-seq, for example, it is no longer necessary for translation-modulating substances to traverse cellular membranes or to extract ribosomes from a large number of living cells,” says Vogel, outlining the advantages of the technique. “You also need a lot less of the often expensive substance that you want to study, such as a new antibiotic that can only be produced on a small scale. INRI-seq therefore also saves time and money.”

    Higher success rate in the experiment

    The research team demonstrated how well the system works using a synthetically generated transcriptome of the bacterium Escherichia coli. Compared to a technically similar study on living cells, INRI-seq identified almost four times more sites where translation processes are initiated, demonstrating its high sensitivity.

    Therefore, Vogel and his team are in no doubt that “INRI-seq bears great potential as an alternative method for studying translation process and thus also substances that can influence these processes”.

    University of Wurzburg

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