In this issue of Molecular Cell, Ye et al. (2015) demonstrate that mTORC1 globally regulates miRNA biogenesis under nutrient-rich conditions via the E3 ubiquitin ligase Mdm2, which promotes Drosha degradation.

Enceladus is a target of future missions designed to search for existing life or its precursors. Recent flybys of Enceladus by the Cassini probe have confirmed the existence of a long-lived global ocean laced with organic compounds and biologically available nitrogen. This immediately suggests the possibility that life could have begun and may still exist on Enceladus. Here we will compare the ...

In origins of life research, it is important to understand the difference between conjecture and hypothesis. This commentary explores the difference and recommends alternative hypotheses as a way to advance our understanding of how life can begin on the Earth and other habitable planets. As an example of how this approach can be used, two conditions have been proposed for sites conducive to the...

1. The Composition of Life 1.1. Origin of organic molecules 1.2. RNA and the origin of life 2. Cell as the unit of life 2.1. Cell theory 2.2. The theory of organisms 2.3. Cell size 3. The diversity of life 3.1. Origin of the first cell 3.2. The endosymbiont hypothesis 4. Cellular diversity 4.1. Plant tissue diversity 4.1.1. Dermal tissue 4.1.2. Vascular tissue 4.1.3. Ground tissue 4.2. Animal t...

“There is something rather than nothing because something is more stable”, wrote Victor Stenger about the universe [1]. The same applies to the origin of life; but what sort of something, and where? Thermodynamics and life itself are the surest guides. Thermodynamics, because life is more stable than non-life only under certain farfrom-equilibrium conditions. Life, because the best explanation ...