Protein evolution is irreversible

In their paper "An epistatic ratchet constrains the direction of glucocorticoid receptor evolution", Bridgham, Ortlund and Thornton show that sequence evolution of glucocorticoid receptor is irreversible. Although they only show it for one protein, it may be a general principle. This means that even if evolution was repeated in exactly the same conditions, a completely different world would result, by chance.

La Ciencia Española no necesita tijeras

Or, translated: Spanish Science does not need scissors.

This week the Spanish 2010 budget was presented by the Government - the main conclusion is a deep cut in the budget. For instance, the Spanish National Research Council, will have to make do with 15% less than in 2009.

At the same time, more more is lent to enterprises - yes, lent, not given - to mask the cuts. These loans are presented in the budget on equal terms as the "gifts" to universities, to research institutes (but also companies), and to individual researchers as specific research grants.

This is something the president, Zapatero, had promised not to do when coming to power.

To follow the suggestion in this blog, I post a specific reason for not cutting science funds here:

- Funds for science in Spain should not be cut (or converted into loans for companies as the minister Garmendia is doing), because spending, and output, is still well below average for developed countries.

Paul Kammerer

Although I am not a genetics expert, the Science news article "The Case of the Midwife Toad: Fraud or Epigenetics? piqued my interest. It would be interesting to see if someone finally manages to repeat Paul Kammerer's experiment.

Constraints and Restraints

In the paper "A short history of SHELX" by George Sheldrick (Acta Crystallographica A, 2008, 64, 112-122) is explained very clearly something I did not completely realise:

- CONstraints lower the number of variables to refine, while

- REstraints augment the number of observations.

What follows from this is that for low resolution structures introducing extra constraints (for instance strict NCS) is more efficient than introducing extra restraints, the reason being that you need more than one observation per refined variable.

This is not actually implemented in all crystallographic protein structure refinement programs, which I think is a shame.

Bacterial cultures that can count up to three

In a recent issue of Science, Friedland et al. report bacterial cultures that can count up to 3 - albeit without knowing it themselves. What they count are pulses of arabinose, a sugar - and they report via fluorescence signal.

Journal club 15/6/2009

In their paper "Chaperonin overexpression promotes genetic variation and enzyme evolution", Tokuriki and Tawfik show protein stability is a major constraint in protein evolution. Chaperonin over-expression can, at least partially, mitigate it, see Nature 459, 668-673. In the same issue of Nature, Mueller et al. present the structure of an alpha-helical toxin pore and propose a detailed mechanism for pore-formation, see pages 726-730.

Modern humans come from East Africa, near de Red Sea

As reported in the issue of Science of 1 May 2009, p. 575

by Ann Gibbons in "Africans' Deep Genetic Roots Reveal Their Evolutionary Story":

The data also confirm earlier research indicating that the source population for the out-of-Africa migration of modern humans came from east Africa near the Red Sea.