A reevaluation of the genus Malassezia by means of genome comparison

Results of a study of the genus Malassezia on the basis of genome characters confirm that two species should be maintained, M. furfur and M. pachydermatis. The two forms associated with skin disease, frequently referred to as Pityrosporum orbiculare and P. ovale, were found to be synonymous, the name M. furfur having priority. Malassezia pachydermatis, hitherto regarded as a strictly zoophilic species, may also be found on humans.     

Small G proteins in peroxisome biogenesis: the potential involvement of ADP-ribosylation factor 6

Background  

Peroxisomes execute diverse and vital functions in virtually every eukaryote. New peroxisomes form by budding from pre-existing organelles or de novo by vesiculation of the ER. It has been suggested that ADP-ribosylation factors and COPI coatomer complexes are involved in these processes.     

Scanning electron microscopy on microsporum audouini complex

Several strains of Microsporum audouini, M. langeroni and M. rivalieri were observed by light and scanning electron microscopies. The macroaleuriospore shape and ornamentation were illustrated and compared for the 3 species as the pectinate hyphae for M. langeroni and M. rivalieri and the chlamydospores and particular hyphae for M. audouini and M. langeroni. The 3 species are morphologically very close but they are distinguishable from each other on the basis of morphology, geographic distribution and pathogenicity.     

A critical analysis of disease-associated DNA polymorphisms in the genes of cattle,goat, sheep,and pig

Genetic variations through their effects on gene expression and protein function underlie disease susceptibility in farm animal species. The variations are in the form of single nucleotide polymorphisms, deletions/insertions of nucleotides or whole genes, gene or whole chromosomal rearrangements, gene duplications, and copy number polymorphisms or variants. They exert varying degrees of effects on gene action, such as substitution of an amino acid for another, shift in reading frame and premature termination of translation, and complete deletion of entire exon(s) or gene(s) in diseased individuals. These factors influence gene function by affecting mRNA splicing pattern or by altering/eliminating protein function. Elucidating the genetic bases of diseases under the control of many genes is very challenging, and it is compounded by several factors, including host × pathogen × environment interactions. In this review, the genetic variations that underlie several diseases of livestock (under monogenic and polygenic control) are analyzed. Also, factors hampering research efforts toward identification of genetic influences on animal disease identification and control are highlighted. A better understanding of the factors analyzed could be better harnessed to effectively identify and control, genetically, livestock diseases. Finally, genetic control of animal diseases can reduce the costs associated with diseases, improve animal welfare, and provide healthy animal products to consumers, and should be given more attention.     

Evolution des populations bactériennes dans les sédiments des marais maritimes de l'Ile Grande pollués par I'Amoco Cadiz Evolution of Bacterial Populations in Salt Marsh Sediments of Ile Grande Polluted by Amoco Cadiz

Microbial investigations on heterotrophic bacteria (MPN counts, adenylates charge, growth rate and enzymatic activities) and hydrocarbon utilizing microorganisms (MPN counts) were carried out during three years in the salt marshes of Ile Grande. The aim was to follow their recovery after oil pollution. Oil degradation is related to bacterial activity (depending on site, depth in the soil, redox level and hydrocarbon concentrations). The results for the three years show a significant enhancement of the microflora during the first year (corresponding to removal of n. alkanes) followed by a decrease in bacterial activity which persisted for over two years. The activity of the heterotrophic bacterial population is deeply disturbed compared with unoiled sites, and these shifts remain detectable three years after oiling. This study does not modify our previous estimation regarding the recovery of the salt marshes.     

DNA base composition and DNA relatedness among species of Trichosporon Behrend

The nuclear DNa of 28 species (30 strains investigated) of yeasts classified currently or previously in the genus Trichosporon. was analysed for its molar percentage of guanine + cytosine (mol% G+C). This criterion, together with biochemical characteristics, suggested the separation of the organisms studied into two groups. The first group, which appears related to the Ascomycetes, includes thirteen species with a G+C content lower than 50 mol% (34.7–48.8), and lacks urease (except T. margaritiferum). The second group appears related to the Basidiomycetes and includes fifteen species with a G+C content higher than 50 mol% (57–64) and has the ability to hydrolyse urea.A DNA homology experiment with T. beigelii and twelve other species of the second group showed very low values of complementarity with T. beigelii-labeled DNA. All these species must be considered as taxa other than T. beigelii.     

Next-Generation Sequencing in the Mycology Lab

New state-of-the-art techniques in sequencing offer valuable tools in both detection of mycobiota and in understanding of the molecular mechanisms of resistance against antifungal compounds and virulence. Introduction of new sequencing platform with enhanced capacity and a reduction in costs for sequence analysis provides a potential powerful tool in mycological diagnosis and research. In this review, we summarize the applications of next-generation sequencing techniques in mycology.     

Microbial utilization of coral mucus in long term in situ incubation over a coral reef

The purpose of this study was to assess degradation and utilization of the mucus produced by 3 coral reef Anthozoa (Sarcophyton, Fungia and Acropora) by microorganisms. This was achieved by carrying out long term in situ incubations at Nouméa lagoon (New Caledonia).The microbial population including bacterial and eukaryotic cells was monitored by cell counts, cultures of mucus degraders, and by estimation of microbial activity from the pool of adenylates and enzymatic activity. In addition the chemical composition (C and N) of the mucus was monitored and its morphological features were observed by scanning electron microscope (SEM).Only slight differences were found between the 3 types of mucus studied. On the whole, they follow the same pattern of change. After a short bacterial growth phase (4 days), a bloom of eukaryotes (Flagellates, Ciliates and Diatoms) was observed. This eukaryote population remained constant for at least 10 days. A similar pattern has been described in the breakdown of detritus of plant origin.Several observations suggest that bacteria utilize only certain components of mucus, the most widely used being proteins, triglycerides and wax esters; these latter two compounds are known to be the dissolved photosynthetic products released by zooxanthellae during mucus secretion. Neither bacteria nor eukaryotes completely degrade the mucus web even after 21 days of incubation. The likelihood that mucus excretion is a defensive reaction against physical and chemical stresses might explain why mucus is a poor, or even inhibiting medium for the bacterial degraders isolated from the mucus itself.