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91.
CXC chemokine ligand 10 controls viral infection in the central nervous system: evidence for a role in innate immune response through recruitment and activation of natural killer cells
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Trifilo MJ Montalto-Morrison C Stiles LN Hurst KR Hardison JL Manning JE Masters PS Lane TE 《Journal of virology》2004,78(2):585-594
How chemokines shape the immune response to viral infection of the central nervous system (CNS) has largely been considered within the context of recruitment and activation of antigen-specific lymphocytes. However, chemokines are expressed early following viral infection, suggesting an important role in coordinating innate immune responses. Herein, we evaluated the contributions of CXC chemokine ligand 10 (CXCL10) in promoting innate defense mechanisms following coronavirus infection of the CNS. Intracerebral infection of RAG1(-/-) mice with a recombinant CXCL10-expressing murine coronavirus (mouse hepatitis virus) resulted in protection from disease and increased survival that correlated with a significant increase in recruitment and activation of natural killer (NK) cells within the CNS. Accumulation of NK cells resulted in a reduction in viral titers that was dependent on gamma interferon secretion. These results indicate that CXCL10 expression plays a pivotal role in defense following coronavirus infection of the CNS by enhancing innate immune responses. 相似文献
92.
VerBerkmoes NC Shah MB Lankford PK Pelletier DA Strader MB Tabb DL McDonald WH Barton JW Hurst GB Hauser L Davison BH Beatty JT Harwood CS Tabita FR Hettich RL Larimer FW 《Journal of proteome research》2006,5(2):287-298
Rhodopseudomonas palustris is a purple nonsulfur anoxygenic phototrophic bacterium that is ubiquitous in soil and water. R. palustris is metabolically versatile with respect to energy generation and carbon and nitrogen metabolism. We have characterized and compared the baseline proteome of a R. palustris wild-type strain grown under six metabolic conditions. The methodology for proteome analysis involved protein fractionation by centrifugation, subsequent digestion with trypsin, and analysis of peptides by liquid chromatography coupled with tandem mass spectrometry. Using these methods, we identified 1664 proteins out of 4836 predicted proteins with conservative filtering constraints. A total of 107 novel hypothetical proteins and 218 conserved hypothetical proteins were detected. Qualitative analyses revealed over 311 proteins exhibiting marked differences between conditions, many of these being hypothetical or conserved hypothetical proteins showing strong correlations with different metabolic modes. For example, five proteins encoded by genes from a novel operon appeared only after anaerobic growth with no evidence of these proteins in extracts of aerobically grown cells. Proteins known to be associated with specialized growth states such as nitrogen fixation, photoautotrophic, or growth on benzoate, were observed to be up-regulated under those states. 相似文献
93.
Dodd SJ Hurst MR Glare TR O'Callaghan M Ronson CW 《Applied and environmental microbiology》2006,72(10):6584-6592
Some strains of Serratia entomophila and S. proteamaculans cause amber disease of the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae). Three genes required for virulence, sepABC, are located on a large plasmid, pADAP. Sequence analysis suggests that the sepABC gene cluster may be part of a horizontally mobile region. This study presents evidence for the putative mobility of the sep genes of pADAP. Southern blot analysis showed that orthologues of the sep genes reside on plasmids within S. entomophila, S. liquefaciens, S. proteamaculans, and a plasmid from Yersinia frederiksenii. Three plasmids hybridized to the pADAP sep virulence-associated region but not the pADAP replication and conjugation regions. Subsequent DNA sequence analysis of the Y. frederiksenii sep-like genes, designated tcYF1 and tcYF2, showed that they had 88% and 87% DNA identity to sepA and sepB, respectively. These results indicate that the sep genes are part of a discrete horizontally mobile region. 相似文献
94.
J. M. C. K Jayawardana Martin Westbrooke Michael Wilson Cameron Hurst 《Hydrobiologia》2006,568(1):169-185
Reed invasion is a common phenomenon of open streams with disturbed riparian vegetation in river catchments. Knowledge of
the effects of such vegetation change on aquatic communities is fundamental to river management. Macroinvertebrate fauna in
Phragmites australis (Cav.) Trin. ex Steud. and open bank habitats were examined in three rivers in central Victoria in order to understand the
effect of such littoral habitat on macroinvertebrates. Data were analysed using Partially Nested Factorial ANOVA with season,
river and habitats as main effects. Habitat structure had a significant effect (p<0.05) on macroinvertebrate species richness, however this was not seasonally consistent across the three rivers. There was
a significant increase (p<0.05) in macroinvertebrate taxa richness in Phragmites habitats during winter and spring seasons. Total abundance of taxa showed no consistent significant differences in the two
habitats. Results of Canonical Analysis of Principle Coordinates indicated significant differences (p<0.05) in macroinvertebrate assemblages between Phragmites and bare bank habitats in all seasons. Habitat selection by taxa could be related to the microphysical environment of the
habitats. This study suggests that reed beds create important littoral habitat structures which support diverse macroinvertebrate
assemblages. 相似文献
95.
96.
The evolution of cytoplasmic incompatibility types: integrating segregation, inbreeding and outbreeding
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Cytoplasmic incompatibility (CI) is a reproductive incompatibility induced by maternally transmitted bacteria of the genera Wolbachia and Cardinium. In the simplest form of CI, offspring from infected males and uninfected females suffer from increased mortality. However, it has been noted that crosses between males and females carrying different strains of infection are often also incompatible. The evolutionary processes leading to the emergence of new CI-compatibility types are still not resolved. Here, we develop a model that extends previous theoretical approaches by including segregation of bacterial strains during transmission as well as a continuum of breeding systems ranging from inbreeding (complete sib mating) to outbreeding (complete sib-mating avoidance). Our results demonstrate that (1) with segregation of strains, evolution is unlikely to lead to new CI types that co-occur as a double infection with the preexisting one, (2) inbreeding substantially hampers the evolution of new CI types, and (3) outbreeding facilitates the evolution of new CI types. Our model also provides a hypothesis on the evolutionary origin of CI. 相似文献
97.
Fehér T Bogos B Méhi O Fekete G Csörgo B Kovács K Pósfai G Papp B Hurst LD Pál C 《Molecular biology and evolution》2012,29(10):3153-3159
Although both genotypes with elevated mutation rate (mutators) and mobilization of insertion sequence (IS) elements have substantial impact on genome diversification, their potential interactions are unknown. Moreover, the evolutionary forces driving gradual accumulation of these elements are unclear: Do these elements spread in an initially transposon-free bacterial genome as they enable rapid adaptive evolution? To address these issues, we inserted an active IS1 element into a reduced Escherichia coli genome devoid of all other mobile DNA. Evolutionary laboratory experiments revealed that IS elements increase mutational supply and occasionally generate variants with especially large phenotypic effects. However, their impact on adaptive evolution is small compared with mismatch repair mutator alleles, and hence, the latter impede the spread of IS-carrying strains. Given their ubiquity in natural populations, such mutator alleles could limit early phase of IS element evolution in a new bacterial host. More generally, our work demonstrates the existence of an evolutionary conflict between mutation-promoting mechanisms. 相似文献
98.
MicroRNAs (miRNAs) have emerged as key regulators of gene expression. Intragenic miRNAs account for ~50% of mammalian miRNAs. Classic studies reported that they are usually coexpressed with host genes. Here, using genome-wide miRNA and gene expression profiles from five sample sets, we show that evolutionarily conserved ('old') intragenic miRNAs tend to be coexpressed with host genes, but non-conserved ('young') ones rarely do so. This result is robust: in all sample sets, the coexpression rate of young miRNAs is significantly lower than that of conserved ones even after controlling for abundance. As a result, although young miRNAs dominate in human genome, the majority of intragenic miRNAs that show coexpression with host genes are phylogenetically old ones. For younger miRNAs, extrapolation of their expression profiles from those of their host genes should be treated with caution. We propose a model to explain this phenomenon in which the majority of young miRNAs are unlikely to be coexpressed with host genes; however, for some fraction of young miRNAs coexpression with their host genes, initially imbued by chromatin level effects, is advantageous and these are the ones likely to embed into the system and evolve ever higher levels of coexpression, possibly by evolving piggybacking mechanisms. 相似文献
99.
Mehlmer N Parvin N Hurst CH Knight MR Teige M Vothknecht UC 《Journal of experimental botany》2012,63(4):1751-1761
Calcium has long been acknowledged as one of the most important signalling components in plants. Many abiotic and biotic stimuli are transduced into a cellular response by temporal and spatial changes in cellular calcium concentration and the calcium-sensitive protein aequorin has been exploited as a genetically encoded calcium indicator for the measurement of calcium in planta. The objective of this work was to generate a compatible set of aequorin expression plasmids for the generation of transgenic plant lines to measure changes in calcium levels in different cellular subcompartments. Aequorin was fused to different targeting peptides or organellar proteins as a means to localize it to the cytosol, the nucleus, the plasma membrane, and the mitochondria. Furthermore, constructs were designed to localize aequorin in the stroma as well as the inner and outer surface of the chloroplast envelope membranes. The modular set-up of the plasmids also allows the easy replacement of targeting sequences to include other compartments. An additional YFP-fusion was included to verify the correct subcellular localization of all constructs by laser scanning confocal microscopy. For each construct, pBin19-based binary expression vectors driven by the 35S or UBI10 promoter were made for Agrobacterium-mediated transformation. Stable Arabidopsis lines were generated and initial tests of several lines confirmed their feasibility to measure calcium signals in vivo. 相似文献
100.
Busby JN Landsberg MJ Simpson RM Jones SA Hankamer B Hurst MR Lott JS 《Journal of molecular biology》2012,415(2):359-371
Yersinia entomophaga MH96 is a native New Zealand soil bacterium that secretes a large ABC-type protein toxin complex, Yen-Tc, similar to those produced by nematode-associated bacteria such as Photorhabdus luminescens. Y. entomophaga displays an exceptionally virulent pathogenic phenotype in sensitive insect species, causing death within 72 h of infection. Because of this phenotype, there is intrinsic interest in the mechanism of action of Yen-Tc, and it also has the potential to function as a novel class of biopesticide. We have identified genes that encode chitinases as part of the toxin complex loci in Y. entomophaga MH96, P. luminescens, Photorhabdus asymbiotica and Xenorhabdus nematophila. Furthermore, we have shown that the secreted toxin complex from Y. entomophaga MH96 includes two chitinases as an integral part of the complex, a feature not described previously in other ABC toxins and possibly related to the severe disease caused by this bacterium. We present here the structure of the Y. entomophaga MH96 Chi1 chitinase, determined by X-ray crystallography to 1.74 Å resolution, and show that a ring of five symmetrically arranged lobes on the surface of the Yen-Tc toxin complex structure, as determined by single-particle electron microscopy, provides a good fit to the Chi1 monomer. We also confirm that the isolated chitinases display endochitinase activity, as does the complete toxin complex. 相似文献