A single gene can disrupt the sleep-wake cycle

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Neurons in drosophila brain marked with green fluorescent protein. The most colored parts highlight the mushroom bodies, a key center for sleep regulation.

All living organisms are subject to an internal biological rhythm, which controls many physiological processes. In humans in particular, this internal clock follows a 24-hour cycle and occurs even in the absence of external triggers, such as changes in light or temperature. Using the genetic model organism Drosophila melanogaster, a team from the University of Geneva (UNIGE), Switzerland, has discovered that the Nf1 gene is essential for the regulation of the sleep-wake cycle. This gene is also involved in a common genetic disease in humans – neurofibromatosis – which leads to the formation of tumors in the nervous system. This discovery could help explain certain symptoms observed in patients suffering from this disease, in particular the disturbance of their sleep.

The article was published in the journal Nature Communications.

Check out the UNIGE press release.

The defensive arsenal of plant roots

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Visualization of suberin (induced toward the root tip at the bottom) in Arabidopsis thaliana, with an intensity-stained gradient.

Plants adapt to their nutritional needs by modifying the permeability of their roots through the production or degradation of a cork-like layer called suberin. By studying the regulation of this protective layer in Arabidopsis thaliana, Marie Barberon‘s group has discovered four molecular factors responsible for the genetic activation of suberin. The identification of these factors allowed the production of plants with roots that are continuously covered – or, on the contrary, completely devoid – of suberin. These factors are of major interest for the selection of plants more resistant to environmental stresses.

The article was published in the journal Proceedings of the National Academy of Sciences (PNAS), on September 21st 2021.

Check out the UNIGE press release.

Understanding how elephants use their trunk

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The elephant proboscis (trunk) exhibits an extraordinary kinematic versatility as it can manipulate a single blade of grass but also carry loads up to 270 kilograms. Using motion-capture technologies developed for the movie industry, Pr Milinkovitch‘s group demonstrates that the complex behaviours of the elephant trunk emerge from the combination of a finite set of basic movements such as the propagation of an inward curvature and the formation of pseudo-joints. In addition, the Swiss team demonstrates that the elephant trunk velocity obeys a mathematical law observed in human hand drawing movements.

The article was published in the journal Current Biology, on August 23rd 2021.

Check out the UNIGE press release.

Induction of a chromatin boundary in vivo upon insertion of a TAD border

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Proposed mechanistic model of Btg1 expression changes.

In mammals, the genome is spatially segmented in three-dimensional domains called TADs, which are separated by more or less strict boundaries. This organization seems to be important to properly implement gene regulation through the action of long-distance enhancers. Nevertheless, genome-wide studies on this relationship are not easy to resolve, and the relevance of each TAD boundary often needs to be taken on a case-by-case basis.

Andréa Willemin and Lucille Lopez-Delisle, from the laboratories of Denis Duboule, showed that a TAD boundary, when randomly inserted in a different chromosome, retained its ability to reshape the chromatin landscape and disturb gene expression.

This work co-supervised by Eddie Rodríguez-Carballo, led Andréa Willemin to obtain the Prix Arditi for the best Master Thesis in Biology in 2020.

The article was published in PLoS Genetics on July 22nd, 2021.

Chromosomes separation under focus

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Representation of the separase-secretin and separase-CCC complexes, with artistic representation of the DNA in the background.

During cell division, chromosomes are duplicated and separated so that one copy of each chromosome is inherited by each of the two emerging daughter cells. Correct distribution of chromosomes requires high accuracy and defects in this process can cause aberrant distribution of chromosomes and facilitate cancer development. By analyzing the structure of the protein responsible for chromosome separation, an international team, led by Andreas Boland from the department of molecular biology, has shed light on the mechanisms controlling this essential player in cell division.

The article was published in the journal Nature, on July 21st 2021.

Check out the UNIGE press release.

Inherited memories of a chromosomal site

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Most biological traits are inherited through genes, but there are exceptions to this rule. Florian Steiner‘s and Monica Gotta‘s groups have been investigating the location of centromeres – specific sites on chromosomes that are essential for cell division. They found that in the small worm Caenorhabiditis elegans, the transmission of the correct location of these sites to the offspring is not mediated by genes, but by an epigenetic memory mechanism.

The article was published in the journal PLOS Biology, on July 6th 2021.
Check out the UNIGE press release and Reinier Prosée’s short animated video.

2021 Physical Biology Circle Meeting

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International Focus Workshop 13 – 15 September 2021

The Physical Biology Circle Meeting will bring together European researchers at the leading edge of research in experimental and theoretical biological physics. The meeting aims at discussing research topics at the interface between physics and biology and at fostering interactions between key institutions playing a role in this quickly growing field.

Emphasis is put on the active participation of researchers on the PhD and postdoc levels with lots of opportunities for contributed talks by PhD students and postdocs. All fields of biophysics are welcome.

Among others, Prof. Guillaume Salbreux and Prof. Karsten Kruse are node coordinators. The meeting will be online and possibly, partly at the Max Planck Institute for the Physics of Complex Systems in Dresden.

Application deadline is 31st July 2021

Further information: www.pks.mpg.de/cmbp21/

EMBO Workshop “Physics of living systems: From molecules to tissues”

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From June 7-10, 2021, the Cluster of Excellence Physics of Life (PoL) is hosting a 4-day EMBO workshop to discuss recent advances in the field of biological physics, focusing on emergent principles that govern the dynamic organization of living matter.

Among other physicists, Prof. Guillaume Salbreux is in charge of the scientific organization.