Sunday, September 17, 2017

The Vital Question, by Nick Lane - Part 2

Mitochondrion. Source: US NIH
" So what about sex, or the nucleus, or phagocytosis? [...] If each of these traits arose by natural selection which they undoubtedly did and all of the adaptive steps offered some small advantage which they undoubtedly did then we should see multiple origins of eukaryotic traits in bacteria. But we don't. This is little short of an evolutionary 'scandal'. "
Nick Lane The Vital Question (2015)

In my previous post I commented on the first part of Nick Lane's book, which deals with the proton-motive force and the origin of life. This second post focuses on the second half of the book, which explores the origin of complex life (i.e. eukaryotic cells).

If the first half of the book was equally part history of the field and part new hypotheses, the second half leans clearly more towards hypothetical ideas albeit including many facts, and backed with rigorous thinking. Lane's big idea is the following. Most traits that differentiate eukaryotes from prokaryotes (cell and genome sizes, nucleus, introns, sexual reproduction) ultimately follow from a single and singular event: the endosymbiosis event that created mitochondria. For Lane, the organelles that power respiration in all eukaryotic cells are the one special ingredient that permitted the development of cellular complexity.

Sunday, July 09, 2017

The Vital Question, by Nick Lane

“In the end, respiration and burning are equivalent; the slight delay in the middle is what we know as life.”
This quote, from Nick Lane’s book The Vital Question (2015), is both poetic and true, which is the mark of great popular science writing. What Lane’s book attempts to do (and in my opinion succeeds in doing) is to radically change our perspective on life by showing us the crucial role played by energy. 

Lane is a biochemist at University College London and already the author of three books. I think there’s something to be said about popular science written by scientists, as opposed to science journalists, in the sense that they can sometimes achieve much more than educating. For example, they can fundamentally change our understanding of some topics (that certainly happened to me on some occasions). Actually, reading The Vital Question reminded me of reading Richard Dawkins’ The Selfish Gene many years ago, and Lane’s book did for me with biochemistry what Dawkins did with genetics and evolutionary theory: it opened a window into a fascinating new landscape. 

Friday, March 17, 2017

Cooperation shapes the spatial patterns of bacterial organization

Cooperative bacterial strains colonizing a surface
Bacteria colonize surfaces in all environments. That could be the surfaces of soil aggregates, of rocks in a stream bed, of plant leaves, of animal skin, or that could be the surface of your showerhead... On such surfaces microbes establish complex communities ('biofilms') that can contain many different interacting species. These various species are usually not randomly distributed in the biofilm, but rather organized depending on their environmental preferences (for example some like well-aerated areas, others not so much...) and on the type of interactions that they have with each other. This can result in complex patterns of organization that manifest at the microscopic scale and up to the millimeter scale. Such patterns are not trivial, as they can sustain microbial activity and functions that would not be possible in a well-mixed environment, which has importance for biotechnology applications as well.

In a new study published this month, we examined the role of cooperation in shaping spatial patterns of bacterial organization on wet surfaces. The paper is available online and is entitled 'Cooperation in carbon source degradation shapes spatial self-organization of microbial consortia on hydrated surfaces'. Our idea was that a feeding dependency between two partners would directly control their distribution in space, hence imposing a specific pattern. We used a simple model system made of two bacterial strains that could grow using the chemical compound toluene (a hydrocarbon), but only when they were working together as a 'team' (a bacterial consortium in the jargon).