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31.
Mateus F Santana José CF Silva Eduardo SG Mizubuti Elza F Araújo Bradford J Condon B Gillian Turgeon Marisa V Queiroz 《BMC genomics》2014,15(1)
Background
Cochliobolus heterostrophus is a dothideomycete that causes Southern Corn Leaf Blight disease. There are two races, race O and race T that differ by the absence (race O) and presence (race T) of ~ 1.2-Mb of DNA encoding genes responsible for the production of T-toxin, which makes race T much more virulent than race O. The presence of repetitive elements in fungal genomes is considered to be an important source of genetic variability between different species.Results
A detailed analysis of class I and II TEs identified in the near complete genome sequence of race O was performed. In total in race O, 12 new families of transposons were identified. In silico evidence of recent activity was found for many of the transposons and analyses of expressed sequence tags (ESTs) demonstrated that these elements were actively transcribed. Various potentially active TEs were found near coding regions and may modify the expression and structure of these genes by acting as ectopic recombination sites. Transposons were found on scaffolds carrying polyketide synthase encoding genes, responsible for production of T-toxin in race T. Strong evidence of ectopic recombination was found, demonstrating that TEs can play an important role in the modulation of genome architecture of this species. The Repeat Induced Point mutation (RIP) silencing mechanism was shown to have high specificity in C. heterostrophus, acting only on transposons near coding regions.Conclusions
New families of transposons were identified. In C. heterostrophus, the RIP silencing mechanism is efficient and selective. The co-localization of effector genes and TEs, therefore, exposes those genes to high rates of point mutations. This may accelerate the rate of evolution of these genes, providing a potential advantage for the host. Additionally, it was shown that ectopic recombination promoted by TEs appears to be the major event in the genome reorganization of this species and that a large number of elements are still potentially active. So, this study provides information about the potential impact of TEs on the evolution of C. heterostrophus.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-536) contains supplementary material, which is available to authorized users. 相似文献32.
Gabriela G Loots Patrick SG Chain Shalini Mabery Amy Rasley Emilio Garcia Ivan Ovcharenko 《BMC bioinformatics》2006,7(1):307-8
Background
There are several isolated tools for partial analysis of microarray expression data. To provide an integrative, easy-to-use and automated toolkit for the analysis of Affymetrix microarray expression data we have developed Array2BIO, an application that couples several analytical methods into a single web based utility. 相似文献33.
In vitro and in vivo intraluminal perfusions of the uterovaginal junction of the oviduct were performed in an attempt to quantitate sperm release from the uterovaginal sperm host glands (UV-SHG) of breeder hens. Spermatozoa were present in the perfusate at all time periods examined. However, the quantity of spermatozoa recovered showed a significant (P<0.0001) decline over a 2-h perfusion period in all experiments. Furthermore, histological examination of the perfused oviduct revealed significantly lower percentages (P<0.05) of UV-SHG containing spermatozoa compared to unperfused control oviducts. The perfusion techniques used in this study seemed to influence the pattern of sperm release from the storage glands. 相似文献
34.
As a drug-sparing approach in early development, vibratory milling has been used for the preparation of nanosuspensions of poorly water-soluble drugs. The aim of this study was to intensify this process through a systematic increase in vibration intensity and bead loading with the optimal bead size for faster production. Griseofulvin, a poorly water-soluble drug, was wet-milled using yttrium-stabilized zirconia beads with sizes ranging from 50 to 1500 μm at low power density (0.87 W/g). Then, this process was intensified with the optimal bead size by sequentially increasing vibration intensity and bead loading. Additional experiments with several bead sizes were performed at high power density (16 W/g), and the results were compared to those from wet stirred media milling. Laser diffraction, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and dissolution tests were used for characterization. Results for the low power density indicated 800 μm as the optimal bead size which led to a median size of 545 nm with more than 10% of the drug particles greater than 1.8 μm albeit the fastest breakage. An increase in either vibration intensity or bead loading resulted in faster breakage. The most intensified process led to 90% of the particles being smaller than 300 nm. At the high power intensity, 400 μm beads were optimal, which enhanced griseofulvin dissolution significantly and signified the importance of bead size in view of the power density. Only the optimally intensified vibratory milling led to a comparable nanosuspension to that prepared by the stirred media milling. 相似文献
35.
SG Bradley F Marciano-Cabral 《Journal of industrial microbiology & biotechnology》1996,17(3-4):314-321
Amoeboid organisms are phylogenetically diverse, some being more closely related to plants or metazoans than to each other. Amoeboid organisms are ecologically successful, having been isolated on all continents, including Antarctica, as well as being the main predators controlling bacterial populations in soil. The classification of these organisms has historically relied upon morphological characteristics. The application of electron microscopy, comparison of enzymic profiles after electrophoretic separation, and analysis of nucleic acid fractions have provided reliable bases for classifying amoeboid organisms. The extent of diversity of these organisms has been recognized, as methods to detect, culture, characterize and identify them has increased. It is reasonable to anticipate that the current 40 000 species of protists will increase substantially as amoeboid organisms are cultivated from poorly accessible niches and from extreme environs. 相似文献
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