[The double helix model of DNA: Its impact on biology and medicine 70 years after its initial publication]. / El modelo de la doble hélice del ADN: su impacto en biología y medicina a 70 años de su publicación inicial.

The 70th anniversary of the publication of the double helix model for the structure of deoxyribonucleic acid has oppened the opportunity for reflections and to debate the specific role of each of the original protagonists. Here we review how this discovery has lead to our current medical knowledge and practice, and discuss what we think were the actual contributions of each of these scientists.

El 70 aniversario de la publicación del modelo de doble hélice para la estructura del ácido desoxirribonucleico abre la oportunidad de reflexionar y debatir el papel específico de cada uno de los protagonistas originales. Aquí revisamos las consecuencias de este descubrimiento en nuestro conocimiento y práctica médica actuales, y discutimos lo que creemos que fueron las contribuciones reales de cada uno de estos científicos.

The euryhaline yeast Debaryomyces hansenii has two catalase genes encoding enzymes with differential activity profile.

Debaryomyces hansenii is a spoilage yeast able to grow in a variety of ecological niches, from seawater to dairy products. Results presented in this article show that (i) D. hansenii has an inherent resistance to H2O2 which could be attributed to the fact that this yeast has a basal catalase activity which is several-fold higher than that observed in Saccharomyces cerevisiae under the same culture conditions, (ii) D. hansenii has two genes (DhCTA1 and DhCTT1) encoding two catalase isozymes with a differential enzymatic activity profile which is not strictly correlated with a differential expression profile of the encoding genes.

NADP-glutamate dehydrogenase activity is increased under hyperosmotic conditions in the halotolerant yeast Debaryomyces hansenii.

Glutamate plays an important role in osmoprotection in various bacteria. In these cases, increased intracellular glutamate pools are not attributable to the NADP-dependent glutamate dehydrogenase (NADP-GDH) or the glutamate synthase, which do not increase their activities under hyperosmotic conditions, but rather to changes in other enzymes involved in glutamate metabolism. We performed a study which indicates that, as opposed to what happens in bacteria, the activity of NADP-GDH is fivefold higher when the halotolerant yeast Debaryomyces hansenii is grown in the presence of 1 M NaCl, compared with growth in media with no added salt. Since purified NADP-GDH activity in vitro was not enhanced by the presence of salt and was more sensitive to ionic strength than the two isoenzymes from S. cerevisiae, increased enzyme synthesis is the most plausible mechanism to explain our results. We discuss the possibility that increased NADP-GDH activity in D. hansenii plays a role in counteracting the inhibitory effect of high ionic strength on the activity of this enzyme.