Biomedical subjects

U Petrovic

Publications and source records attributed to U Petrovic.

3 recordsLinked to original sources

PubMed2004

Clustering gene expression data with temporal abstractions.

This paper describes a new technique for clustering short time series coming from gene expression data. The technique is based on the labelling of the time series through temporal trend abstractions and a consequent clustering of the series on the basis of their labels. Clustering is performed at three different levels of aggregation of the original time series, so that the results are organized and visualized as a three-levels hierarchical tree. Results on simulated and on yeast data are shown. The technique appears robust and efficient and the results obtained are easy to be interpreted.

Algorithms↗

PubMed2000

Xerotolerant mycobiota from high altitude Anapurna soil, Nepal.

Xerophilic and xerotolerant microfungi were isolated from soil samples collected in Anapurna Mountains, Nepal, at altitudes from 3000 to 5400 m. The total numbers and proportions of xerotolerant and psychrophilic strains in comparison with mesophilic mycobiota were determined by using different enumeration, selective media and four isolation methods. The most extreme xerophilic fungi were taxonomically identified as belonging to the genera Eurotium and Aspergillus. The low water activity of the soil due to dry climate and frequent binding of water in ice crystals favors a high proportion of xerotolerant fungal species. The correlation between xerotolerant and psychrophilic fungi was observed.

Altitude↗

PubMed1999

Salt stress affects sterol biosynthesis in the halophilic black yeast Hortaea werneckii.

Hortaea werneckii is a black yeast recently isolated from salterns in Slovenia. Some of the adaptations of halophilic microorganisms to increased salinity and osmolarity of the environment are alterations in membrane properties. By modulating the fluidity, sterols play an important role as a component of eukaryotic biological membranes. We studied the regulation of sterol biosynthesis in H. werneckii through the activity and amount of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG R), a key regulatory enzyme in the biosynthesis of sterols. We found some differences in the characteristics of HMG R and in its regulation by different environmental salinities in H. werneckii when compared to the mesophilic baker's yeast, Saccharomyces cerevisiae. Our results suggest that halophilic black yeast regulates sterol biosynthesis through HMG R in a different way than mesophiles, which might be a consequence of the different ecophysiology of halophilic black yeasts. From this perspective, H. werneckii is an interesting novel model organism for studies on salt stress-responsive proteins as well as on sterol biosynthesis in eukaryotes.

Ascomycota↗