Un simple cas clinique ne suffit pas à changer la médecine, mais il peut parfois ouvrir de nouvelles pistes. C'est précisément ce qui s'est produit avec cette observation étonnante d'une patiente atteinte d'Alzheimer ayant montré une amélioration temporaire après l'administration de psilocybine.

Votre chat passe ses journées à explorer le quartier avant de rentrer réclamer sa gamelle et quelques caresses ? Selon une nouvelle étude, ces escapades pourraient aussi l'exposer à de nombreux microbes, parasites et virus susceptibles d'être rapportés jusqu'au foyer.

We tend to view ourselves and the complex cells that build us as a distinct branch of the tree of life from the compact, seemingly featureless cells of bacteria and archaea. But we've found that our genome is actually a hybrid, a mish-mash of genes from bacteria and archaea, along with some that have evolved in our own lineage.

Scientists gradually settled on a simple explanation for this: the first complex cells were the product of a fusion between archaeal cells and bacteria, with the bacteria ultimately evolving into the mitochondria, a chemical-power-generating structure that still retains a bit of its own genome. Over time, many of the other bacterial genes were transferred to the nucleus of what was becoming what we now call a eukaryote, intermingling with the archaeal genes there.

But a new study has taken a careful look at some of the genes shared by all eukaryotes and comes to the conclusion that the reality is a little more complicated and that there were several waves of gene transfers from bacteria. The big picture of a merger between bacteria and archaea is still right, but it was only part of a picture where gene transfers among species were commonplace.

Read full article

Comments

© MARK GARLICK/SCIENCE PHOTO LIBRARY

Une simple prise de sang pour prédire la dépression post-partum avant même qu'elle n'apparaisse. C'est la promesse d'un test développé aux États-Unis, capable de détecter ce trouble dans plus de 80 % des cas. Une avancée qui pourrait transformer la prise en charge des jeunes mères.