Isolation of Bacteriophages from Group H Streptococci

Temperate phages were isolated from 5 of the 17 strains of group H streptococci tested.     

Sexualidad y patogenicidad en Aspergillus fumigatus: ¿existe alguna relación?

BackgroundAspergillus fumigatus, like many other fungal species of clinical relevance, has been traditionally regarded as an asexual organism. However, in last few years several pieces of evidence question this such assumption, suggesting that the sexual state of A. fumigatus may still be undiscovered. These investigations have finally led to the recent discovery of a teleomorph stage of A. fumigatus, which has been named Neosartorya fumigata.AimsTo review the most important findings on A. fumigatus sexuality and discuss the possible implications of such findings on its pathogenicity.MethodsA bibliographic search was performed to find the main works that study the sexuality of fungal pathogens and, especially, of A. fumigatus. Moreover, data from our recent investigations in this field were also introduced to the discussion.ResultsThe existence of a teleomorph for A. fumigatus could have significant clinical repercussions, as sexual reproduction might produce offspring with increased virulence and/or resistance to antifungal agents. In this sense, the results of our investigations suggest the existence of an association between the MAT1-1 mating type and the invasiveness of A. fumigatus isolates.ConclusionsThe study of the sexual reproduction of the fungal pathogens and its possible relationship with virulence will continue to be a topic of interest during the next years, not only because of its basic interest, but also for the possible clinical repercussions.     

Germination of desiccated aged akinetes of alkaliphilic cyanobacteria

Morphological and biochemical changes associated with synchronous germination of mature, aged and desiccated akinetes of two alkaliphilic cyanobacteria, Cyanospira rippkae and Cyanospira capsulata, are described. Akinetes of both strains proved to be highly resistant to desiccation, being able to germinate, in the presence of either N₂ or nitrate as nitrogen source, with a germination frequency of more than 90% after seven years of storage in a dried state. The first cell division occurred after 8–10 h of incubation, thereafter the germlings of the two strains followed a different pattern of cell differentiation. Heterocysts were first noted, in a terminal position, at 16–18 h in three-celled germlings of C. capsulata and at 21–24 h in C. rippkae, when germlings were at least seven cells in length. Akinetes of both species possessed, on a per cell basis, almost identical amounts of all photosynthetic pigments but, under nitrogen fixing conditions, photosynthetic activity (oxygen evolution) was detected only after new proteins had been synthesized, before a functional heterocyst was developed and while total nitrogen remained constant. With energy provided by aerobic respiration, a wide range of intracellular amino acids characteristic of proteins was utilised to sustain the new protein synthesis. The end of this biosynthetic activity coincided with the timing of the first cell division. From this stage on, no changes in protein concentration occurred until mature heterocysts were developed. In the presence of nitrate, no significant changes in the major germination events were observed.