How the fly selects its reproductive male

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Even a well-characterized genome, such as that of the Drosophila the so-called fruit fly, still holds surprises. Researchers from the Department of Genetics and Evolution, in collaboration with Cornell University (USA) and the University of Groningen (Netherlands), have discovered an RNA coding for a micro-peptide – a very small protein – that plays a crucial role in the competition between spermatozoa from different males with which the female mates. In addition to shedding new light on this biological mechanism, Robert Maeda and collaborators’ work highlights the importance of small peptides, a class of proteins that is now emerging as a key player in complex biological processes.

The article was published in the journal Proceedings of the National Academy of Sciences (PNAS), on April 5th 2021.

UNIGE Press release

Grigorii Timin wins the Olympus Image of the Year Award 2020 for Europe

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The company Olympus, a well-known provider of microscopes, organised the 2nd Global Image of the Year Light Microscopy Award to celebrate the very best in life science imaging worldwide.

We are very excited that an outstanding image recorded by Grigorii Timin, PhD student in the laboratory of Prof. Michel Milinkovitch has been selected as the best image for Europe.

The Milinkovitch laboratory investigates the development of skin scales in reptiles and Grigorii’s stunning image shows collagen fibers and dermal pigment cells in embryonic skin scales of the African house snake.

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Scaled, armoured or naked: how does the skin of fish evolve?

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Usually scaled, the skin of fish can also be naked or made up of bony plates that form an armour, sometimes even covered with teeth. But how has this skin evolved over the ages? To answer this question, Alexandre Lemopoulos and Juan Montoya have reconstructed the evolution of the protective skin structures in fish, going back to the common ancestor of ray-finned fish, more than 420 million years ago. They found that only fish that had lost their scales were able to develop a bony armour, and that the protective state of their skin influenced their choice of open water or sea floor habitats. This study, published in the journal Evolution Letters, provides a new explanation for the incredible diversity of this lineage of fish, which includes more than 25,000 species.

The article was published in Evolution letters on March 23rd, 2021.

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This study is also covered by other media :

La perte d’écailles chez certains poissons, une histoire d’habitat Sciences et Avenir, 30.03.2021

The skeleton of the malaria parasite reveals its secrets

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Plasmodium is the parasite causing malaria, one of the deadliest parasitic diseases. The parasite requires two hosts —the Anopheles mosquito and the human— to complete its life cycle and goes through different forms at each stage of its life cycle. Transitioning from one form to the next involves a massive reorganisation of the cytoskeleton. Paul Guichard and Virginie Hamel’s group, in collaboration with Mathieu Brochet‘s group from the CMU, has shed new light on the cytoskeleton organisation in Plasmodium. Their research details the organisation of the parasite’s skeleton at an unprecedented scale, adapting a recently developed technique called expansion microscopy. Cells are “inflated” before imaging, providing access to more structural details, at a nanometric scale. The study identifies traces of an organelle called “conoid”, which was thought to be lacking in this species despite its crucial role in host invasion of closely related parasites.

The article was published in PLOS Biology on March 11, 2021.

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This study is also covered by other media :

Du nouveau sur le parasite de la malaria RTS La 1ère / Journal 10h / CQFD*, 12.03.2021

Let there be green!

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Responsible for the green color of plants, the essential mechanisms for the emergence of photosynthesis have just been explored at the level of plant cells. Combining biochemistry, electron microscopy,and 3D computer reconstruction, the astounding phenomenon can now be visualized in moving images over time.

This collaborative study between Emilie Demarsy, the Universities of Neuchâtel (UniNE), Grenoble (F) and ETH Zurich, was published in the journal eLife on 25 February 2021.

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This study is also covered by other media :

Pourquoi les plantes sont vertes RTS La 1ère / Journal 10h / CQFD*, 24.02.2021

Le verdissement des plantes n’a plus de secrets Canal Alpha, 25.02.2021

Of multiple-horned goats and sheep

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Bovidae sometimes display supernumerary horns. For instance, local breeds of sheep genetically selected by generations of breeders, are known for their multiple horns, a condition referred to as ‘polyceraty’. It also happens, particularly in the Alps, that goats spontaneously develop an additional pair of horns. While the genetic causes of this morphological curiosity have long remained unknown, it seems that this mystery has now found its solution. Indeed, a genomic study of many such mutant animals, carried out by the French National Institute for Agricultural and Environmental Research (INRAE) and the union of breeding cooperatives ALLICE together with Pr Denis Duboule’s group, in collaboration with the EPFL and several other research centers distributed over four continents, reveals that all the four-horned goats and sheep analyzed carry a mutations affecting the same gene: HOXD1.

The article was published in the journal Molecular Biology and Evolution on February 16, 2021.

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This study is also covered by other media :

Le mystère du bouc à quatre cornes levé Tribune de Genève, 17.02.2021

Mystère génétique résolu 20 Minutes Genève, 17.02.2021

Le mystère des chèvres et moutons à quatre… swissinfo.ch/fr / swissinfo FR, 17.02.2021

A constitutively monomeric UVR8 photoreceptor confers enhanced UV-B photomorphogenesis

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Coping with UV-B is crucial for plant survival in sunlight. The UV-B photoreceptor UVR8 regulates gene expression associated with photomorphogenesis, acclimation and UV-B stress tolerance. UV-B photon reception by UVR8 homodimers results in monomerization, followed by interaction with the key signaling protein COP1. Roman Ulm’s group, in collaboration with Michael Hothorn‘s group, has discovered a UV-B hypersensitive UVR8 photoreceptor (UVR8G101S) that confers strongly enhanced UV-B tolerance and generated a novel UVR8 variant based on the underlying mutation that shows extremely enhanced constitutive signaling activity. These findings provide key mechanistic insight into how plants respond and acclimate to UV-B radiation.

This article was published in PNAS on February 9, 2021.

Discovery of a phosphate sensing and signaling pathway in plants

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Cells require sufficient amounts of the element phosphorus to build their membranes and to store and copy genetic information. Phosphorus is taken up by cells in the form of inorganic phosphate, an important signaling molecule and energy currency. While we take up sufficient amounts of phosphate with our diet, plants have to mobilize and take up phosphate from the soil, where it is poorly bioavailable. Phosphate thus limits the growth of plants, and phosphate fertilizers have to be used to maximize crop yields. How plant cells measure cellular phosphate levels and how they decide if and when to take up more phosphate is poorly understood.

The Hothorn lab has previously shown that phosphate-rich inositol pyrophosphates are nutrient messengers in plants and identified SPX domains as their cellular receptors. In a new report, the Hothorn, Hiller (Biozentrum Basel) and Fiedler (FMP Berlin) labs now report that inositol pyrophosphates control the activity of the transcription factor PHOSPHATE STARVATION RESPONSE 1 (PHR1). When there is enough phosphate in the cell, inositol pyrophosphates bind to the SPX receptor which in turn binds to PHR1, keeping it in a isolated form unable to active gene expression. When phosphate becomes limiting, inositol pyrophosphates are less abundant, the SPX – PHR1 complex dissociates and the free transcription factor can interact with itself and activate the expression of genes involved in phosphate uptake. This signaling mechanism may now be exploited towards the development of phosphate starvation tolerant crops that would require less phosphate fertilizer.

The article was published in Nature Communications, on January 15th 2021.

 

The wings of a “genetic bird” protect us against viruses

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Modelling of HLA-peptide bindings forming the two wings of a bird in flight.

Do populations from different geographic regions have the same potential for defending themselves against pathogens and against viruses in particular? An analysis of human genomes, especially the HLA genes responsible for the so-called “adaptive” immune system, provide some possible answers to this question. These genes, which vary enormously between individuals, code for molecules capable of recognising the different viruses so they can trigger the appropriate immune response.

Alicia Sanchez-Mazas‘s group, partnering with Cambridge University, has identified the HLA variants that bind to families of viruses most effectively. Their study show that, in spite of the great heterogeneity of HLA variants in individuals, all populations benefit from an equivalent potential when it comes to virus protection.

The article was published in the journal Molecular Biology and Evolution, on December 15th, 2020.

Press release from UNIGE.