Gene expression during Ustilago maydis diploid filamentous growth: EST library creation and analyses

Ustilago maydis is an important model system for the plant pathogenic smut and rust fungi. Critical to the continued development of this model is establishing genomic resources. We have constructed a cDNA library from a forced diploid culture of U. maydis growing as filaments and have generated 7455 ESTs that are assembled into 3074 contiguous sequences. This represents as much as 46% of the coding capacity predicted for U. maydis. BLAST searches with a similarity cutoff of E 相似文献   

Use of genome information for the study of the pathogenesis of fungal infections and the development of diagnostic tools

One of the most exciting advances in Mycology is the application of genomic approaches. The advent of genomics, together with post-genomic studies, promises to revolutionize the studies on the pathogenesis of fungal infections. Approaches include comparative genomics to identify sequences that contribute to infection and disease and functional genomics and proteomics to analyze global patterns of gene and protein expression involved in fungal pathogenesis.     

Bioinformatic identification of Ustilago maydis meiosis genes

In the corn smut pathogen, Ustilago maydis, meiosis and teliospore germination are temporally linked. We review teliospore dormancy and germination in U. maydis and present an overview of meiosis in basidiomycetes. The relevant available expressed sequence tag data is discussed, the databases used in reciprocal best hit blastp analysis are presented and potential U. maydis meiosis genes are identified. The implications of identifying these genes are discussed and hypotheses are presented regarding the control of meiosis in U. maydis.     

Early migration of Sarcocystis neurona in ponies fed sporocysts

Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days PI by bioassays in interferon gamma gene knock out mice (KO) and from cell culture. Microscopic lesions consistent with an EPM infection were observed in brain and spinal cord of ponies killed 7 and 9 days PI. Results suggest that S. neurona disseminates quickly in tissue of naive ponies.     

The effect of cage size on reproductive performance and behavior of C57BL/6 mice

Scientific research has yet of cage size on mouse breeding to conclusively determine the optimal cage size for mice. The authors examined the effect performance and on offspring behavior, which can serve as indications of overall wellbeing. They housed breeding trios of C57BL/6Tac mice in standard or large individually ventilated cages and measured four reproductive parameters： litter size; litter survival to weaning age; average pup weight at 7, 14 and 21 days; and the number of days between litter births. They investigated the behavior of a subset of male and female pups from parents housed in cages of each size in the elevated plus maze test, the open field assay and the acoustic startle test. Cage size had no significant effect on any of the reproductive parameters measured and few or inconsistent effects on behavior in weaned pups. Lab Animal 2007,36（10）     

Randomized controlled trial evaluating rapid pre-screen of cervical cytology specimens.

A randomized controlled trial of 75,355 cervical cytology specimens was performed comparing rapid pre-screen with no pre-screen. While the percentage of cases receiving a final report of definite high-grade abnormality was higher in the no pre-screen arm (no pre-screen = 0.70%, pre-screen = 0.65%), the percentage of cases receiving a final report of possible or definite high-grade abnormality was essentially identical in the two arms of the trial (no pre-screen = 1.22%, pre-screen = 1.21%). In the randomized trial, one extra cytology report of definite high-grade abnormality was made for every 12,568 slides pre-screened. This level of benefit was reduced by about half when rapid pre-screen was adopted as a routine laboratory practice.     

Risk Analysis of Sclerotinia sclerotiorum for Biological Control of Cirsium arvense in Pasture: Ascospore Dispersal

Natural levels of Sclerotinia sclerotiorum ascsospores in the Canterbury region were determined over 3 years by trapping depositing ascospores in dishes containing a selective agar. Mean levels in 'horticulture', 'biocontrol-pasture', 'mixed cropping' and 'pasture' strata were 115, 56, 10 and 3 ascospores m -2 day -1 , respectively. Ascospore deposition downwind of small experimental biocontrol sites was measured on 2 days in 1994 and 9 days in 1997 in late spring. Exponential depletion models scaled up to represent a 1 ha biocontrol site, revealed that dispersing ascospores declined to natural levels at downwind distances of 2.5-7.9 m. These results imply that biological weed control in pasture using S. sclerotiorum creates no greater risk of crop disease than does horticulture, and that under the conditions of our experiments, an isolation distance of 8 m would have sufficed. However, such a safety zone may be inadequate under certain meteorological conditions not encountered in the experiments when ascospores may disperse in larger numbers over longer distances. To complete the information required to build a mechanistic model of spore dispersal (beyond the scope of this paper) which would cope with a variety of meteorological conditions, two studies were conducted on the dynamics of apothecium formation and ascospore release. In a two-year study, apothecium formation was confined to the spring (September-November), and population size peaked in mid October. In a 5-day study, ascospore release occurred during the daytime, reaching a maximum late morning on frost-free days and a lower maximum mid afternoon on days with morning frost.     

Inhibition of Candida albicans Biofilm Formation by Farnesol, a Quorum-Sensing Molecule

Farnesol is a quorum-sensing molecule that inhibits filamentation in Candida albicans. Both filamentation and quorum sensing are deemed to be important factors in C. albicans biofilm development. Here we examined the effect of farnesol on C. albicans biofilm formation. C. albicans adherent cell populations (after 0, 1, 2, and 4 h of adherence) and preformed biofilms (24 h) were treated with various concentrations of farnesol (0, 3, 30, and 300 μM) and incubated at 37°C for 24 h. The extent and characteristics of biofilm formation were then assessed microscopically and with a semiquantitative colorimetric technique based on the use of 2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide. The results indicated that the effect of farnesol was dependent on the concentration of this compound and the initial adherence time, and preincubation with 300 μM farnesol completely inhibited biofilm formation. Supernatant media recovered from mature biofilms inhibited the ability of planktonic C. albicans to form filaments, indicating that a morphogenetic autoregulatory compound is produced in situ in biofilms. Northern blot analysis of RNA extracted from cells in biofilms indicated that the levels of expression of HWP1, encoding a hypha-specific wall protein, were decreased in farnesol-treated biofilms compared to the levels in controls. Our results indicate that farnesol acts as a naturally occurring quorum-sensing molecule which inhibits biofilm formation, and we discuss its potential for further development and use as a novel therapeutic agent.