Quentin

It's an interesting paper. It shows us well the darwinian concept of selection. Bacterias which mute when they are cultivated with an antibiotic are defective bacterias compared to the wild type. But it's better for the bacteria to be defective and survey than to be killed by the antibiotic. We can probably think that we could obtain a reversion in the mechanism of antibiotics resistance (a priority for the WHO, by the way...)... But it's maybe more complicated than it seems. Some resistance ways creates bacterias which seems to be not so defective : e.g. the Staphylococcus aureus and the resistance to Penicillin. A penicillinase is enough ! And after the begining of the antibiotherapy, the penicillin resistance came quickly ! But we can think that we could obtain a reversion in the resistance to oxacillin (or meticillin as you want) because the mechanism is a modification of the proteins which bind the penicillins (PLP2a), and a modification of the peptidoglycan is worse than secreting a little enzym. Maybe by stopping using oxacillim, we may find a solution in the fight against MRSA ? The problem is that it implys treating MSSA without oxacillin (are we going to give vancomycin to everyone !?!) The problem is not so easy... We do not have enough antibiotics. But we can say that there are probably two groups : - resistance linked to a little modification of the bacteria (secreting an enzym, as the penicillinase and so on... or maybe more, considering TEM 3 or TEM 17, which are large spectrum beta lactamases...) ==> No easy reversion, because the bacteria is not so defective - resistance liked to a big modification of the bacteria (like creating a new structure protein, mechanism of the oxacillin resistance for MRSA) ==> Easy reversion, because the bacteria is defective.

I've always thought that separating evolution into macro and microevolution is nonsense. There is a unique evolution. The evolution is not the selection of different combinaisons of allels. This combinaison of allels creates diversity in species. Mixing different allels doesn't create new species. The evolution is supported by the modifications of our DNA, the mutations (deletion, duplication...) Who are we to say that something is microevolution, and something else is macroevolution ? It's just a problem of scale. Evolution is a continuous phenomenon. In France (you probably saw that my english is not perfect ! ), in my Medical School, professors doesn't talk about these two concepts (micro and macroevolution), except one (of histology and cytogenetics), who is known to be a quite radical christian. This makes me think that making a difference with micro and macroevolution is a way to introduce genetics in the theory of creationism. Are people separating evolution into micro and macroevolution necessarily creationists ?