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Aspergillus flavus genomics: gateway to human and animal health, food safety, and crop resistance to diseases 总被引:2,自引:0,他引:2
Aspergillus flavus is an imperfect filamentous fungus that is an opportunistic pathogen causing invasive and non-invasive aspergillosis in humans, animals, and insects. It also causes allergic reactions in humans. A. flavus infects agricultural crops and stored grains and produces the most toxic and potent carcinogic metabolites such as aflatoxins and other mycotoxins. Breakthroughs in A. flavus genomics may lead to improvement in human health, food safety, and agricultural economy. The availability of A. flavus genomic data marks a new era in research for fungal biology, medical mycology, agricultural ecology, pathogenicity, mycotoxin biosynthesis, and evolution. The availability of whole genome microarrays has equipped scientists with a new powerful tool for studying gene expression under specific conditions. They can be used to identify genes responsible for mycotoxin biosynthesis and for fungal infection in humans, animals and plants. A. flavus genomics is expected to advance the development of therapeutic drugs and to provide information for devising strategies in controlling diseases of humans and other animals. Further, it will provide vital clues for engineering commercial crops resistant to fungal infection by incorporating antifungal genes that may prevent aflatoxin contamination of agricultural harvest. 相似文献
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Paired sequence difference in ribosomal RNAs: evolutionary and phylogenetic implications 总被引:12,自引:1,他引:11
Ribosomal RNAs have secondary structures that are maintained by internal
Watson-Crick pairing. Through analysis of chordate, arthropod, and plant 5S
ribosomal RNA sequences, we show that Darwinian selection operates on these
nucleotide sequences to maintain functionally important secondary
structure. Insect phylogenies based on nucleotide positions involved in
pairing and the production of secondary structure are incongruent with
those constructed on the basis of positions that are not. Furthermore,
phylogeny reconstruction using these nonpairing bases is concordant with
other, morphological data.
相似文献
25.
Origin and distribution of epipolythiodioxopiperazine (ETP) gene clusters in filamentous ascomycetes
Nicola J Patron Ross F Waller Anton J Cozijnsen David C Straney Donald M Gardiner William C Nierman Barbara J Howlett 《BMC evolutionary biology》2007,7(1):174
Background
Genes responsible for biosynthesis of fungal secondary metabolites are usually tightly clustered in the genome and co-regulated with metabolite production. Epipolythiodioxopiperazines (ETPs) are a class of secondary metabolite toxins produced by disparate ascomycete fungi and implicated in several animal and plant diseases. Gene clusters responsible for their production have previously been defined in only two fungi. Fungal genome sequence data have been surveyed for the presence of putative ETP clusters and cluster data have been generated from several fungal taxa where genome sequences are not available. Phylogenetic analysis of cluster genes has been used to investigate the assembly and heredity of these gene clusters. 相似文献26.
Liliana Losada Janyce A. Sugui Michael A. Eckhaus Yun C. Chang Stephanie Mounaud Abigail Figat Vinita Joardar Suman B. Pakala Suchitra Pakala Pratap Venepally Natalie Fedorova William C. Nierman Kyung J. Kwon-Chung 《PLoS pathogens》2015,11(4)
Invasive aspergillosis (IA) due to Aspergillus fumigatus is a major cause of mortality in immunocompromised patients. The discovery of highly fertile strains of A. fumigatus opened the possibility to merge classical and contemporary genetics to address key questions about this pathogen. The merger involves sexual recombination, selection of desired traits, and genomics to identify any associated loci. We constructed a highly fertile isogenic pair of A. fumigatus strains with opposite mating types and used them to investigate whether mating type is associated with virulence and to find the genetic loci involved in azole resistance. The pair was made isogenic by 9 successive backcross cycles of the foundational strain AFB62 (MAT1-1) with a highly fertile (MAT1-2) progeny. Genome sequencing showed that the F9
MAT1-2 progeny was essentially identical to the AFB62. The survival curves of animals infected with either strain in three different animal models showed no significant difference, suggesting that virulence in A. fumigatus was not associated with mating type. We then employed a relatively inexpensive, yet highly powerful strategy to identify genomic loci associated with azole resistance. We used traditional in vitro drug selection accompanied by classical sexual crosses of azole-sensitive with resistant isogenic strains. The offspring were plated under varying drug concentrations and pools of resulting colonies were analyzed by whole genome sequencing. We found that variants in 5 genes contributed to azole resistance, including mutations in erg11A (cyp51A), as well as multi-drug transporters, erg25, and in HMG-CoA reductase. The results demonstrated that with minimal investment into the sequencing of three pools from a cross of interest, the variation(s) that contribute any phenotype can be identified with nucleotide resolution. This approach can be applied to multiple areas of interest in A. fumigatus or other heterothallic pathogens, especially for virulence associated traits. 相似文献
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J. Yu T. E. Cleveland J. R. Wilkinson B. C. Campbell J. H. Kim H. S. Kim D. Bhatnagar G. A. Payne W. C. Nierman 《Mycotoxin Research》2006,22(1):16-21
Aflatoxins are the most toxic and carcinogenic naturally occurring mycotoxins. They are produced primarily byAspergillus flavus andA. parasiticus. In order to better understand the molecular mechanisms that control aflatoxin production, identification of genes usingA. flavus expressed sequence tags (ESTs) and microarrays is currently being performed. Sequencing and annotation ofA. flavus ESTs from a normalizedA. flavus cDNA library identified 7,218 unique EST sequences. Genes that are putatively involved in aflatoxin biosynthesis, regulation
and signal transduction, fungal virulence or pathogenicity, stress response or antioxidation, and fungal development were
identified from these ESTs. Microarrays containing over 5,000 uniqueA. flavus gene amplicons were constructed at The Institute for Genomic Research. Gene expression profiling under aflatoxin-producing
and non-producing conditions using this microarray has identified hundreds of genes that are potentially involved in aflatoxin
production. Further investigations on the functions of these genes by gene knockout experiments are underway. This research
is expected to provide information for developing new strategies for controlling aflatoxin contamination of agricultural commodities. 相似文献
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Mitochondrial gene order is not conserved in arthropods: prostriate and metastriate tick mitochondrial genomes 总被引:25,自引:15,他引:10
The entire mitochondrial genome was sequenced in a prostriate tick, Ixodes
hexagonus, and a metastriate tick, Rhipicephalus sanguineus. Both genomes
encode 22 tRNAs, 13 proteins, and two ribosomal RNAs. Prostriate ticks are
basal members of Ixodidae and have the same gene order as Limulus
polyphemus. In contrast, in R. sanguineus, a block of genes encoding NADH
dehydrogenase subunit 1 (ND1), tRNA(Leu)(UUR), tRNA(Leu)(CUN), 16S rDNA,
tRNA(Val), 12S rDNA, the control region, and the tRNA(Ile) and tRNA(Gln)
have translocated to a position between the tRNA(Glu) and tRNA(Phe) genes.
The tRNA(Cys) gene has translocated between the control region and the
tRNA(Met) gene, and the tRNA(Leu)(CUN) gene has translocated between the
tRNA(Ser)(UCN) gene and the control region. Furthermore, the control region
is duplicated, and both copies undergo concerted evolution. Primers that
flank these rearrangements confirm that this gene order is conserved in all
metastriate ticks examined. Correspondence analysis of amino acid and codon
use in the two ticks and in nine other arthropod mitochondrial genomes
indicate a strong bias in R. sanguineus towards amino acids encoded by
AT-rich codons.
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