Non-coding RNAs (ncRNAs) existing widely in many living organisms are functional RNA molecules, function directly as structural or regulatory RNAs in organisms. Although large and diverse populations of ncRNAs have been extensively studied and well understood in animals and plants, few reports could be found about ncRNAs in fungi. Recently, with the development of modern biological techniques, a number of ncRNAs have been identified in fungi, including snoRNA-derived RNAs, long non-coding RNAs, small interfering RNAs (siRNAs), dsRNA Killer viruses, and novel classes of ncRNAs discovered in filamentous fungi. These ncRNAs play important roles in gene transcription and translation, RNA processing and modifying, chromatin structure, and even fungal pathogenicity. Therefore, studies on ncRNAs in fungi may shed light on the regulatory system of gene expression and the characteristics of fungal growth, and even provide some clues towards understanding pathogenic mechanisms of pathogenic fungi, which will contribute to the treatment of fungal diseases. Here, we reviewed the discovery of fungal ncRNAs, their origins and processing, classification, and biological functions, aiming to establish a theoretical foundation and basis for deep understanding of fungal ncRNAs in future.

Fungal infections are a frequent occurrence in medical practice due to increasing numbers of immunosuppressed patients. New antifungal medications have been developed and it has become evident that different fungi require different treatments as some are intrinsically resistant to these drugs. Thus, it is imperative that pathologists recognize the limitations of histopathologic diagnosis regarding speciation of fungal infections and advocate for the use of different techniques that can help define the genus and species of the fungus present in the specimen they are studying. In this review we present the use of in situ hybridization as an important adjunct for the diagnosis of fungal diseases, the different techniques that have been used for fungal identification, and the limitations that these techniques have.

Kodamaea (Pichia) ohmeri is an unusual yeast-form fungus that has recently been identified as an important etiology of fungemia, endocarditis, cellulitis, funguria and peritonitis in immunocompromised patients. We report a case of K. ohmeri fungemia in a 34-year-old hospitalized patient with thrombophlebitis. The patient was admitted to the hospital for evaluation and management of an acquired tracheo-esophageal fistula secondary to an impacted denture. Fever developed on hospital day 22, and physical exam revealed right arm superficial thrombophlebitis at the site of the peripheral venous catheter that was confirmed by Doppler ultrasound. The peripheral vein was removed and blood cultures from hospital day 22 and 23 grew yeast species. The yeast was subsequently identified to be K. ohmeri by Vitek II and API20C and was confirmed by 18S rRNA gene sequencing. The fungemia and right arm phlebitis was successfully treated with a 2-week course of micafungin therapy. This is the first case of K. ohmeri fungemia in a patient that was successfully treated with micafungin.

Yeasts are ubiquitous in their distribution and populations mainly depend on the type and concentration of organic materials. The distribution of species, as well as their numbers and metabolic characteristics were found to be governed by existing environmental conditions. Marine yeasts were first discovered from the Atlantic Ocean and following this discovery, yeasts were isolated from different sources, viz. seawater, marine deposits, seaweeds, fish, marine mammals and sea birds. Near-shore environments are usually inhabited by tens to thousands of cells per litre of water, whereas low organic surface to deep-sea oceanic regions contain 10 or fewer cells/litre. Aerobic forms are found more in clean waters and fermentative forms in polluted waters. Yeasts are more abundant in silty muds than in sandy sediments. The isolation frequency of yeasts fell as the depth of the sampling site is increased. Major genera isolated in this study were Candida, Cryptococcus, Debaryomyces and Rhodotorula. For biomass estimation ergosterol method was used. Classification and identification of yeasts were performed using different criteria, i.e. morphology, sexual reproduction and physiological/biochemical characteristics. Fatty acid profiling or molecular sequencing of the IGS and ITS regions and 28S gene rDNA ensured accurate identification.

Candida lusitaniae is an emerging opportunistic pathogen which exhibits an unusual antifungal susceptibility pattern. We describe a case of fatal renal infection due to C. lusitaniae in a very low birth weight neonate who was treated with short courses of fluconazole given alternately with amphotericin B. A colony morphology switching was detected on the standard primary culture medium by changes in colony size. Switching was shown to affect deeply the susceptibility to amphotericin B. Afterwards, the switched phenotype developed a cross resistance to fluconazole and itraconazole. Several issues raised by this case are discussed in the light of an extensive review of the literature. Our observations point out the importance of both the detection of colony morphology switching and the close monitoring of antifungal susceptibility in the management of infections due to C. lusitaniae. A judicious therapeutic strategy should prevent the acquisition of multidrug resistance during antifungal therapy.

The 70 published sequences of group II introns from fungal and plant mitochondria and plant chloroplasts are analyzed for conservation of primary sequence, secondary structure and three-dimensional base pairings. Emphasis is put on structural elements with known or suspected functional significance with respect to self-splicing: the exon-binding and intron-binding sites, the bulging A residue involved in lariat formation, structural domain V and two isolated base pairs, one of them involving the last intron nucleotide and the other one, the first nt of the 3\' exon. Separate sections are devoted to the 29 group II-like introns from Euglena chloroplasts and to the possible relationship of catalytic group II introns to nuclear premessenger introns. Alignments of all available sequences of group II introns are provided in the APPENDIX.

Group I introns form a structural and functional group of introns with widespread but irregular distribution among very diverse organisms and genetic systems. Evidence is now accumulating that several group I introns are mobile genetic elements with properties similar to those originally described for the omega system of Saccharomyces cerevisiae: mobile group I introns encode sequence-specific double-strand (ds) endoDNases, which recognize and cleave intronless genes to insert a copy of the intron by a ds-break repair mechanism. This mechanism results in: the efficient propagation of group I introns into their cognate sites; their maintenance at the site against spontaneous loss; and, perhaps, their transposition to different sites. The spontaneous loss of group I introns occurs with low frequency by an RNA-mediated mechanism. This mechanism eliminates introns defective for mobility and/or for RNA splicing. Mechanisms of intron acquisition and intron loss must create an equilibrium, which explains the irregular distribution of group I introns in various genetic systems. Furthermore, the observed distribution also predicts that horizontal transfer of intron sequences must occur between unrelated species, using vectors yet to be discovered.