Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DIRS-1 is a retroelement from the slime mold Dictyostelium discoideum. Until recently only two related retrotransposons had been described: PAT from the nematode Panagrellus redivivus and Prt1 from the zygomycete fungus Phycomyces blakesleeanus. Analyses of the reverse transcriptase sequences encoded by these three elements suggested that they were closely related to each other and more distantly related to the Ty3/gypsy Long Terminal Repeat (LTR) retroelements. They have several unusual structural features that distinguish them from typical LTR elements. For instance, they each encode a tyrosine recombinase (YR), but not a DDE-type integrase or an aspartic protease. Although the DIRS-1-related elements are bordered by terminal repeats these differ from typical LTRs in a number of ways. In DIRS-1, for example, the terminal repeats are inverted (complementary), non-identical in sequence, and the outer edges of the terminal sequences are repeated (adjacent to each other) in the internal region. PAT has so-called "split" direct repeats in which the unrelated terminal sequences appear as direct repeats adjacent to each other in the internal region. The only repetition displayed by Prt1 is the presence of short inverted terminal repeats, but the sequenced copy of this element is believed to be a truncated version of an element with a structure resembling DIRS-1. The unusual structure of the terminal repeats of the DIRS1-like elements appears to be related to their replication via free circular intermediates. Site-specific recombination is believed to integrate the circle without creating duplications of the target sites. In recognition of these important distinctions it is proposed that the retrotransposons that encode tyrosine recombinases be called the tyrosine recombinase (or YR) retrotransposons. Recently a large number of additional YR retrotransposons have been described, including elements from fungi (zygomycetes and basidiomycetes), plants (green algae) and a wide range of animals including nematodes, insects, sea urchins, fish and amphibia, while remnants of elements related to DIRS-1 occur in the human genome. The complete set of YR retrotransposons can be divided into two major groups, the DIRS elements and the Ngaro elements, the two groups forming distinct clades on phylogenetic trees based on alignments of RT/RH and recombinase sequences, and also having some structural distinctions. A third group of transposable elements, which we call Cryptons, also carry tyrosine recombinases. These elements do not encode a reverse transcriptase and so are believed to be DNA transposons not retrotransposons. They have been detected in several pathogenic fungi, including the basidiomycete Cryptococcus neoformans, and the ascomycetes Coccidioides posadasii and Histoplasma capsulatum. Sequence comparisons suggest that the Crypton YRs are related to those of the YR retrotransposons. We suggest that the YR retrotransposons arose from the combination of a Crypton-like YR DNA transposon and the RT/RH encoding sequence of a retrotransposon.
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PMID:DIRS-1 and the other tyrosine recombinase retrotransposons. 1609 11

The tetracycline (TET) promoter has been used in several systems as an inducible regulator of gene expression. In control analyses, the standard Candida albicans laboratory strain SC5314 was found to have altered susceptibility to a variety of antifungal drugs in the presence of relatively high concentrations (50-200 microg ml(-1)) of TET. Altered susceptibility was most notable with exposure to amphotericin B (AMB), with a 32-fold increase in susceptibility, and terbinafine (TRB), with a 32-fold decrease in susceptibility. The TET/AMB synergy was observed in several clinical isolates of C. albicans and in the distantly related species Aspergillus fumigatus and Cryptococcus neoformans. The TET/AMB synergy is not related to efflux pump activity, as determined by FACS analyses and by analysis of a strain containing efflux pump deletions. Gene expression analyses by luciferase and by quantitative real-time reverse transcriptase PCR failed to identify significant alterations in expression of any genes associated with resistance. C. albicans grown with TET for 48 h does show a reduction in total cellular ergosterol. Analysis of growth curves suggests that the TET effect is associated with lack of a diauxic shift, which is related to a loss of mitochondrial function. MitoTracker fluorescent dye was used to demonstrate that TET has a direct effect on mitochondrial function. These results demonstrate the need for careful analysis of TET effects when using a TET-inducible promoter, especially in studies that involve antifungal drugs. This study defines some limits to the use of the TET-inducible promoter, and identifies effects on cells that are the result of TET exposure alone, not the result of expression of a targeted gene.
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PMID:Tetracycline alters drug susceptibility in Candida albicans and other pathogenic fungi. 1831 42

Several studies have shown that migratory birds play an important role in the ecology, circulation and dissemination of pathogenic organisms. In October 2006, a health status evaluation was performed on a large population of migratory birds passing through the territory of Ustica (Italy), an island located on the migration route of many species of birds to Africa, and various laboratory tests were conducted. In total, 218 faecal swabs and the internal organs of 21 subjects found dead in nets were collected for bacteriological and virological examination, including avian influenza and Newcastle disease. In addition, 19 pooled fresh faecal samples were collected for mycological examination. The bacteriological analysis produced 183 strains belonging to 28 different species of the Enterobacteriaceae family. In particular, Salmonella bongori, Yersinia enterocolitica and Klebsiella pneumonia strains were isolated. Almost all of the isolates were susceptible to sulphamethoxazole/trimethoprime (99.4%), cefotaxime (98.9%), nalidixic acid (96.7%), chloramphenicol (95.6%), and tetracycline (93.4%). Alternatively, many strains were resistant to ampicillin (42.6%), amoxicillin-clavulanic acid (42.6%), and streptomycin (43.7%). According to reverse transcriptase-polymerase chain reaction analysis, all of the samples were negative for the M gene of avian influenza virus. Moreover, isolation tests conducted on specific pathogen free eggs were negative for avian influenza and Newcastle disease. Several hyphomycetes and yeasts belonging to different genera were present in the specimens, and Cryptococcus neoformans was observed in a pooled faecal sample. Antibiotic resistance in wildlife can be monitored to evaluate the impact of anthropic pressure. Furthermore, migratory birds are potential reservoirs of pathogenic agents; thus, they can be regarded as sentinel species and used as environmental health indicators.
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PMID:Pathogenic microorganisms carried by migratory birds passing through the territory of the island of Ustica, Sicily (Italy). 2181 20


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