Monday, January 30, 2012


Ready-to-wear or prêt-à-porter is the term for factory-made clothing, in standardized sizes, as distinct from haute-couture (high-fashion) design clothing. The former is based upon a pattern that is then duplicated and advertised to raise the visibility of the designer. The latter is endowed with great doses of novelty and creativity. In fact, it is believed that fashion design anticipates costumer tastes and, actually, marks the next tendencies. Fashion is everywhere and references to anything that is the current trend in interior design, furniture, food, music,...and science?

Can we consider science under the light of fashion? Are there prêt-à-porter and  haute-couture science? Are there trending topics? At least in the Microbiology field this is the case.

Monday, January 9, 2012

Illuminating virulence

The advent of molecular methods made necesary to revise the Koch´s postulates, formulated in 1890, as general guidelines that should be followed to identify pathogens causing diseases. As a result, Stanley Falkow established the molecular version of Koch's postulates to guide the identification of microbial genes encoding virulence factors. Falkow established five experimental criteria that a gene must fulfill to be considered a virulence factor. A criterium almost never addressed by scientists is "The gene, which causes virulence, must be expressed during infection." It has been always considered enough to test whether specific inactivation of the gene is associated to a measurable loss of virulence. Actually, the golden standard is to demonstrate in vivo (using suitable animal/plant models) that allelic replacement of the mutated gene leads to restoration of virulence.

However, wouldn´t it be interesting to know exactly when and where the virulence gene is expressed? Certainly this may help to understand the in vivo role of the virulence factor: is it required only for the initial colonization of the tissues? Is it necesary to fight phagocytic cells?, is the expression of this factor coordinated with those of other factors?,...Moreover, are there virulenece factors expressed only in vivo and therefore absolutely dispensable in vitro? These questions led scientists to develop experimental approaches to enlighten virulence gene expression. Conceptually, the methods were originally conceived upon the premise (now considered fact) that most virulence genes are transcriptionally induced at one or more times during infection