Estudio de la distribución ambiental de los hongos del género Scedosporium en el País Vasco. Identificación de especies por técnicas moleculares.

El complejo de especies Scedosporium/Pseudallescheria está compuesto por diferentes especies de hongos filamentosos. De las cinco más habituales y utilizadas en este estudio existen tres especies de patógenos oportunistas clínicamente importantes, S. apiospermum, S prolificans y S. aurantiacum, que generan scedosporiosis especialmente en individuos inmuncocomprometidos. El aumento del número de este tipo de pacientes en los últimos años está elevando la incidencia de los casos de scedoporiosis. Scedosporium spp. se encuentran frecuentemente en hábitats humanizados y con presencia de contaminación. En este trabajo, se ha realizado un estudio para determinar su presencia en algunos hábitats de la Comunidad Autónoma del País Vasco (CAPV) y conocer su distribución, empleando técnicas microbiológicas y moleculares. No se aisló ninguna cepa del género en las playas de la CAPV, mientras que si que se encontraron en parques urbanos, aislándose la mayor cantidad de cepas y variedad de especies del género en las muestras de Araba. Por otro lado, se identificaron las especies del género mediante PCR, encontrándose cepas de S. prolificans, S. aurantiacum, S. dehoogii y P. minutispora. Además, se comprobó que los primers disponibles S. apiospermum no permitían discriminarlo del resto de especies.

Online exercise for the design and simulation of PCR and PCR-RFLP experiments

[EN] Background: Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism of PCR products (PCR-RFLP) are extensively used molecular biology techniques. An exercise for the design and simulation of PCR and PCR-RFLP experiments will be a useful educational tool. Findings: An online PCR and PCR-RFLP exercise has been create that requires users to find the target genes,compare them, design primers, search for restriction endonucleases, and finally to simulate the experiment. Each user of the service is randomly assigned a gene from Escherichia coli; to complete the exercise, users must design an experiment capable of distinguishing among E. coli strains. By applying the experimental procedure to all completely sequenced E. coli, a basic understanding of strain comparison and clustering can also be acquired. Comparison of results obtained in different experiments is also very instructive. Conclusions: The exercise is freely available at http://insilico.ehu.es/edu.

Identification of Sex and Female’s Reproductive Stage in Commercial Fish Species through the Quantification of Ribosomal Transcripts in Gonads

The estimation of maturity and sex of fish stocks in European waters is a requirement of the EU Data Collection Framework as part of the policy to improve fisheries management. On the other hand, research on fish biology is increasingly focused in molecular approaches, researchers needing correct identification of fish sex and reproductive stage without necessarily having in house the histological know-how necessary for the task. Taking advantage of the differential gene transcription occurring during fish sex differentiation and gametogenesis, the utility of 5S ribosomal RNA (5S rRNA) and General transcription factor IIIA (gtf3a) in the molecular identification of sex and gametogenic stage was tested in different economically-relevant fish species from the Bay of Biscay. Gonads of 9 fish species (, Atlantic, Atlantic-chub and horse mackerel, blue whiting, bogue, European anchovy, hake and pilchard and megrim), collected from local commercial fishing vessels were histologically sexed and 5S and 18S rRNA concentrations were quantified by capillary electrophoresis to calculate a 5S/18S rRNA index. Degenerate primers permitted cloning and sequencing of gtf3a fragments in 7 of the studied species. 5S rRNA and gtf3a transcript levels, together with 5S/18S rRNA index, distinguished clearly ovaries from testis in all of the studied species. The values were always higher in females than in males. 5S/18S rRNA index values in females were always highest when fish were captured in early phases of ovary development whilst, in later vitellogenic stages, the values decreased significantly. In megrim and European anchovy, where gonads in different oogenesis stages were obtained, the 5S/18S rRNA index identified clearly gametogenic stage. This approach, to the sexing and the quantitative non-subjective identification of the maturity stage of female fish, could have multiple applications in the study of fish stock dynamics, fish reproduction and fecundity and fish biology in general.