Toxoplasmosis rids its host of all fear

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Toxoplasma gondii is a neurotropic parasite that infects all warm-blooded animals, including humans. Its objective is to reach the intestines of felids, the definitive host in which it reproduces sexually. To do so, the parasite first infects mice and drastically alters their behaviour. The natural aversion of mice toward cats is decreased – a phenomenon called fatal attraction – making them easy preys.

Using a set of complementary behavioral tests, Ivan Rodriguez and Dominique Soldati-Favre groups showed that T. gondii lowers general anxiety in infected mice, increases explorative behaviors, and surprisingly alters predator aversion without selectivity toward felids.

Their findings refute the myth of a selective loss of cat fear in T. gondii-infected mice and point toward widespread immune-related alterations of behaviors.

The study was published in Cell Reports on January 14, 2020.

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A novel protease contributes to the repair of DNA-protein crosslinks

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DNA-protein crosslinks (DPCs) are formed in the course of normal cell metabolism. However, their prolonged persistence can be extremely toxic, cause genome instability and promote diseases such as cancer.

The Stutz laboratory, together with the Kornmann (University of Oxford) and Loewith groups,describes a new mechanism required for the efficient DPC disassembly. Through a yeast genetic screen, Serbyn and collaborators identified the enigmatic Ddi1 protease as a new candidate degrading the protein moiety of DPCs. The authors show that Ddi1 helps to resolve a broad variety of DNA-protein crosslinks and functions independently of the known pathways involved in proteolytic DPC elimination.

Loss of Ddi1 sensitizes cells to several compounds that trap DPCs, including approved anti-cancer drugs. The latter provides novel insights into the putative mechanisms of drug resistance often observed in therapeutics.

The study was published in Molecular Cell on January 2, 2020.

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The elephant’s trunk will inspire a revolutionary robot

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An international team, including the group of Professor Michel Milinkovitch, will analyse the African elephant’s trunk, and its exceptional agility and versatility, to create a new generation of manipulative robots capable of operating in unstable environments, adapting quickly to unexpected situations and performing a multitude of concrete tasks.

Read the press release

Conférences 2020: Modéliser le réel

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Modéliser le réel: un outil et un défi pour la science

Les conférences organisées par l’UNIGE et Culture&Rencontre en janvier-février 2020 se consacrent à la modélisation du vivant et de phénomènes naturels et ses applications dans différents domaines scientifiques, dont le climat, la biologie et l’environnement.

L’histoire d’un lézard: quand Darwin rencontre Von Neumann et Turing

Prof. Michel Milinkovitch – Mercredi 8 janvier 2020, 20h

Jusqu’où peut-on modéliser le monde qui nous entoure?

Prof. Bastien Chopard – Mercredi 15 janvier 2020, 20h

Modélisation et ADN préhistorique: à la recherche de nos origines

Dr Mathias Currat – Mercredi 22 janvier 2020, 20h

Comprendre le climat grâce aux simulations numériques

Dre Maura Brunetti – Mercredi 29 janvier 2020, 20h

Un ordinateur et des maths pour simuler la matière et le vivant

Prof. Assyr Abdulle – Mercredi 5 février 2020, 20h

Entrée libre

Aula du Collège de Saussure – 9, Vieux-Chemin-d’Onex, Petit-Lancy

culture-rencontre.ch/conferences

Topoisomerases promote replication fork pausing at proteinaceous barriers

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Living organisms have to faithfully duplicate all the DNA in their chromosomes once and only once during every cell division. Replication forks pause/slow/arrest/stall during progression through chromosomes at certain tight DNA/protein complexes known as Replication Fork Barriers (RFB).  This pausing is promoted by the Fork Pausing Complex (FPC, composed of the Tof1 and Csm3 proteins in budding yeast) and opposed by Rrm3 helicase, a motor-like protein believed to displace obstacles.

Maksym Shyian and collaborators in the Shore laboratory have now discovered that the Tof1-Csm3 complex promotes fork pausing independently of Rrm3 helicase, in contrast to an old model. Instead the Fork Pausing Complex was found to mediate topoisomerase I (Top1) association with the replisome, which, together with Top2, is essential for fork slowdown (replisome sTOP mechanism).

The study was published in Genes & Development on December 5, 2019.

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