Are the liquid droplets in cells spandrels?

Spedale degli Innocenti (detail)Forty years ago Stephen Jay Gould and Richard Lewontin introduced what they called spandrels, to the field of evolutionary biology. My impression is that this idea has been controversial in evolutionary biology ever since. Spandrels in the original sense of the word are illustrated above. The word spandrel comes from architecture, and basically it refers to the parts of the arches above which have the blue discs with a relief person in them. They are the spaces between the arch and the roof. The point that inspired Gould and Lewontin, is that arches are directly functional parts of archtecture, they hold up the roof. But by their very nature arches leave gaps, that is unavoidable but not directly functional. These gaps can be filled in by spandrels, which themselves are not directly functional — the ceiling will not collapse if they are removed.

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Capturing sunlight in droplets

RubiscoLife on Earth, including ourselves, relies totally on photosynthesis. Photosynthesis pulls carbon from carbon dioxide in the air to make the molecules of which plants are made of. Then we eat these plants, and, if we are not vegan, the products of animals that eat these plants. Photosynthesis, like everything else in biology, is the product of evolution. Very simply speaking there are two schools of thought on evolution. The first is that it is an incredible process that has produced marvels such as a soaring eagle with eyesight keen enough to see a rabbit a kilometre away. The second is that it is a blind process that gradually cobbles together just-about-working solutions to the problem of living and reproducing.

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Eating for ten trillion

Adults are recommended to eat about 2000 kilocalories per day. As this is an energy divided by a time it is a power consumption, and in the proper units, it is about 100 Watts. The power consumption of our bodies is a pretty basic feature of how our bodies work, but there is not much known about why a 80 kg guy like me needs 100 W, not 10 or 1000 W. We know* our brain needs of order 10 W, and our heart about 1 W, but for example we have only a poor idea of why our brain burns through 10 Joules every second.

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Stuck in wet cement

I spent part of this week at the kick-off meeting for an EU-funded PhD training network: Engineered Calcium-Silicate-Hydrates for Applications (ERICA for short).  The network is run from Surrey and I was invited along to give a talk, and to help out. These calcium-silicate-hydrates are better known as cement. Cement is, very roughly speaking, a type of artificial stone in the sense that when poured it crystallises to form a semi-crystalline solid. The world’s most widely used construction material, concrete, is basically cement plus gravel filler. Concrete is not the most glamorous, but it is strong and above all it is cheap, less than £100 for a ton.

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Puzzling crystals in the drizzle

 

The life of an academic involves a certain amount of travel, in my case to Manchester in January. This as glamorous as it sounds, the drizzle has been unrelenting. Although on the bright side I was able to finish my talk for tomorrow in the Lass o Gowrie, which I can recommend; friendly barstaff, and the Citrus IPA was good. Tomorrow, I am going to give a talk about growing crystals, in particular growing crystals of a small molecule called glycine. We* studied the glycine molecule because when crystallised from water, it forms not one but two types of crystals.

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Dragon-kings, black swans and an anti-HIV drug

paris_dksornetteNext week, I am off to Paris for a workshop, so I am writing my talk. Above is a plot of French cities. The x-axis is the log of the rank of the city, where the ranking of the city is by size, i.e., the first point (shown in pink) is for France’s largest city, Paris, at an a x value of log(1)=0, while the second point is France’s second largest city, Marseille, at a value log(2)=0.30, the third is Lyon at log(3)=0.48, etc. The y axis is the population of the city, raised to the power c = 0.18. This value is a fitting parameter, the value of 0.18 is the one that makes the data closest to a straight line — as you can see for this value of c the data falls on a pretty decent straight line.

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Self-assembly pope and self-assembling proteins in soap

Over the Christmas period I have been trying out a few beers, including Brewdog’s weirdly named Self Assembly Pope. This beer is a porter, with some cocoa, coconut and vanilla added to spice it up. It is a pretty good porter, although I am not a big fan of coconut, on its own or in beer, and so probably will not be coming back to it*. What I will be doing in 2017 is working on getting membrane proteins to self-assemble into as large and as regular crystals as possible. This is part of an EU-wide network on membrane-protein crystallisation that will be starting in 2017. Membrane proteins are proteins that live in back-to-back layers of soapy molecules — which is what cell membranes are. Membrane proteins are important as many (by some measures a majority) of drugs target these proteins.

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Crystals both large and small

Cristales cueva de NaicaAbove are crystals in a cave in the Mexican state of Chihuahua. They are huge, note that the person in the picture shows the scale. The crystals are up to 10 m long, have masses of tens of tons, and are made of gypsum, a form of calcium sulphate. It is estimated that they took hundreds of thousands of years to grow. So around about the time our ancestors were wandering around Africa, a tiny nucleus formed, and started to grow. Hundreds of thousands of years later, we have these enormous crystals.

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Every one is different, no one is perfect, this is a big problem

Snow crystal at minus11C 07Famously, each snow flake is unique, no two are the same. This is really true. As the crystal lattice of ice has six-fold symmetry, so do snow flakes, which are ice crystals. But this symmetry is never perfect. If you rotate the crystal above by 60 degrees then it would look  different, just not as different as if you rotated it by say 45 degrees. If you rotate it by 60 degrees, then you rotate each arm into the position of the next arm and as the arms are roughly similar the crystal will not look very different, bit it will look different.

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