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41.
High temperature and bacteriophages can indirectly select for bacterial pathogenicity in environmental reservoirs 总被引:1,自引:0,他引:1
Friman VP Hiltunen T Jalasvuori M Lindstedt C Laanto E Örmälä AM Laakso J Mappes J Bamford JK 《PloS one》2011,6(3):e17651
The coincidental evolution hypothesis predicts that traits connected to bacterial pathogenicity could be indirectly selected outside the host as a correlated response to abiotic environmental conditions or different biotic species interactions. To investigate this, an opportunistic bacterial pathogen, Serratia marcescens, was cultured in the absence and presence of the lytic bacteriophage PPV (Podoviridae) at 25°C and 37°C for four weeks (N = 5). At the end, we measured changes in bacterial phage-resistance and potential virulence traits, and determined the pathogenicity of all bacterial selection lines in the Parasemia plantaginis insect model in vivo. Selection at 37°C increased bacterial motility and pathogenicity but only in the absence of phages. Exposure to phages increased the phage-resistance of bacteria, and this was costly in terms of decreased maximum population size in the absence of phages. However, this small-magnitude growth cost was not greater with bacteria that had evolved in high temperature regime, and no trade-off was found between phage-resistance and growth rate. As a result, phages constrained the evolution of a temperature-mediated increase in bacterial pathogenicity presumably by preferably infecting the highly motile and virulent bacteria. In more general perspective, our results suggest that the traits connected to bacterial pathogenicity could be indirectly selected as a correlated response by abiotic and biotic factors in environmental reservoirs. 相似文献
42.
Apetroaie C Andersson MA Spröer C Tsitko I Shaheen R Jääskeläinen EL Wijnands LM Heikkilä R Salkinoja-Salonen MS 《Archives of microbiology》2005,184(3):141-151
Producers of cereulide, the emetic toxin of Bacillus cereus, are known to constitute a specific subset within this species. We investigated physiological and genetic properties of 24
strains of B. cereus including two high cereulide producers (600–1,800 ng cereulide mg−1 wet weight biomass), seven average producers (180–600 ng cereulide mg−1 wet weight biomass), four low cereulide producers (20–160 ng cereulide mg−1 wet weight biomass) and 11 non-producers representing isolates from food, food poisoning, human gut and environment. The
13 cereulide producers possessed 16S rRNA gene sequences identical to each other and identical to that of B. anthracis strains Ames, Sterne from GenBank and strain NC 08234–02, but showed diversity in the adk gene (two sequence types), in ribopatterns obtained with EcoRI and PvuII (three types of patterns), in tyrosin decomposition, haemolysis and lecithin hydrolysis (two phenotypes). The cereulide-producing
isolates from the human gut represented two ribopatterns of which one was novel to cereulide-producing B. cereus and two phenotypes. We conclude that the cereulide-producing B. cereus are genetically and biochemically more diverse than hitherto thought. 相似文献
43.
Toskala E Smiley-Jewell SM Wong VJ King D Plopper CG 《American journal of physiology. Lung cellular and molecular physiology》2005,289(3):L454-L459
Little is known about ciliogenesis as it proceeds through the entire airway tree, from the trachea to the terminal bronchioles, especially during the postnatal period. The purpose of this study was to define the spatial and temporal (prenatal and postnatal) pattern of normal cilia development in the mouse. Three airway generations representing the entire airway tree were examined: trachea, lobar bronchi, and terminal bronchiole. Ciliated cells in lung lobe whole mounts were labeled with a fluorescent dye for confocal microscopy, and ciliated cell surface density was measured for each airway generation and age. The same samples were examined by scanning electron microscopy to verify the appearance of ciliated cells among the differentiating epithelium of the airways. Ciliated cells were first detected in the trachea and lobar bronchi at 16 days gestational age (DGA) and in the terminal bronchioles at 18 DGA. Ciliated cell surface density increased with prenatal and postnatal age at all airway levels. However, the ciliated cell surface density of the trachea and lobar bronchi was always greater compared with the terminal bronchiole. In conclusion, the study revealed that in developing tracheobronchial airways of the mouse: 1) Ciliogenesis differs temporally and spatially by airway generation; 2) Ciliated cell surface density increases with age in all airway generations, but density decreases in a proximal to distal direction; and 3) A significant portion of ciliogenesis continues after birth. This study provides a healthy basis for investigations of neonatal pulmonary disease or pollutant toxicity affecting cilia and its functions. 相似文献
44.
Mutka AL Lusa S Linder MD Jokitalo E Kopra O Jauhiainen M Ikonen E 《The Journal of biological chemistry》2004,279(47):48654-48662
Astrocytes secrete cholesterol in lipoprotein particles. Here we show that primary murine embryonic astrocytes secrete endogenously synthesized cholesterol but also the cholesterol precursors desmosterol and lathosterol. In astrocyte membranes, desmosterol and cholesterol were the predominant sterols. Astrocytes derived from Niemann-Pick type C lipidosis (NPC1-/-) mice displayed late endosomal cholesterol deposits, but the secretion of biosynthetic sterols from the cells was not inhibited. Both wild-type and NPC1-/- astrocytes secreted the NPC2 protein. Size-exclusion chromatography combined with electron microscopy showed that the majority of sterols were secreted separately from NPC2 in heterogeneous spherical particles with an average diameter of 20 nm. These data suggest that NPC2 and the majority of sterols secreted from astrocytes are not released together and that the secretion of neither sterols nor NPC2 requires NPC1 function. In addition, the findings reveal a complexity of sterol species in astrocytes and bring up the possibility that some of the effects assigned to astrocyte cholesterol may be attributed to its penultimate precursors. 相似文献
45.
Teplova V Jääskeläinen E Salkinoja-Salonen M Saris NE Serlachius M Li FY Andersson LC 《Acta biochimica Polonica》2004,51(2):539-544
In this study we have investigated the impact of differentiation of neuronal cells on their sensitivity to microbial toxins. We used the human neural crest-derived tumor cell line Paju, which can be induced to differentiation in vitro by treatment with phorbol 12-myristate 13-acetate. Addition of the highly toxic potassium ionophores cereulide (4.5 and 9.0 ng/ml) or valinomycin (20 ng/ml), to cultures of undifferentiated Paju cells caused collapse of the mitochondrial membrane potential - measured with the fluorescent probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetrabenzimidazole carbocyanine iodide (JC-1) followed by detachment of the cells and their apoptotic death. After induced differentiation of the Paju cells, their mitochondria retained the membrane potential upon exposure to the toxins and the cells displayed increased resistance to apoptosis as compared with undifferentiated cells. This effect may be caused by an elevated expression of the anti-apoptotic protein Bcl-2 and of the neuroprotective factor, stanniocalcin, in differentiated cells. 相似文献
46.
Ferrari-Lacraz S Zanelli E Neuberg M Donskoy E Kim YS Zheng XX Hancock WW Maslinski W Li XC Strom TB Moll T 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(9):5818-5826
It has been suggested that the inflammatory cytokine IL-15 plays an important role in the development of several autoimmune diseases, including rheumatoid arthritis. We have generated a unique lytic and antagonistic IL-15 mutant/Fcgamma2a fusion protein (CRB-15) that targets the IL-15R. In the present study we examined the effects of targeting the IL-15R on the prevention and treatment of collagen-induced arthritis (CIA) in mice and probed the possible mechanisms of action of this IL-15 mutant/Fcgamma2a protein. Upon immunization with type II collagen, DBA/1 mice develop severe articular inflammation and destruction. Treatment of DBA/1 mice with a brief course of CRB-15 at the time of type II collagen challenge markedly inhibited the incidence and severity of arthritis. Moreover, in animals with ongoing established arthritis, treatment with CRB-15 effectively blocked disease progression compared with that in control-treated animals. The therapeutic effect of CRB-15 on either disease development or disease progression is remarkably stable, because withdrawal of treatment did not lead to disease relapse. A detailed analysis revealed that treatment with CRB-15 decreased synovitis in the joints; reduced bone erosion and cartilage destruction; reduced in situ production of the proinflammatory cytokines TNF-alpha, IL-1beta, IL-6, and IL-17; and decreased the responder frequency of autoreactive T cells. Our study suggests that the effective targeting of IL-15R-triggered events with CRB-15 can be of therapeutic importance in the treatment of rheumatoid arthritis. 相似文献
47.
Selinheimo E Saloheimo M Ahola E Westerholm-Parvinen A Kalkkinen N Buchert J Kruus K 《The FEBS journal》2006,273(18):4322-4335
A homology search of the genome database of the filamentous fungus Trichoderma reesei identified a new T. reesei tyrosinase gene tyr2, encoding a protein with a putative signal sequence. The gene was overexpressed in the native host under the strong cbh1 promoter, and the tyrosinase enzyme was secreted into the culture supernatant. This is the first report on a secreted fungal tyrosinase. Expression of TYR2 in T. reesei resulted in good yields, corresponding to approximately 0.3 and 1 g.L(-1) tyrosinase in shake flask cultures and laboratory-scale batch fermentation, respectively. T. reesei TYR2 was purified with a three-step purification procedure, consisting of desalting by gel filtration, cation exchange chromatography and size exclusion chromatography. The purified TYR2 protein had a significantly lower molecular mass (43.2 kDa) than that calculated from the putative amino acid sequence (61.151 kDa). According to N-terminal and C-terminal structural analyses by fragmentation, chromatography, MS and peptide sequencing, the mature protein is processed from the C-terminus by a cleavage of a peptide fragment of about 20 kDa. The T. reesei TYR2 polypeptide chain was found to be glycosylated at its only potential N-glycosylation site, with a glycan consisting of two N-acetylglucosamines and five mannoses. Also, low amounts of shorter glycan forms were detected at this site. T. reesei TYR2 showed the highest activity and stability within a neutral and alkaline pH range, having an optimum at pH 9. T. reesei tyrosinase retained its activity well at 30 degrees C, whereas at higher temperatures the enzyme started to lose its activity relatively quickly. T. reesei TYR2 was active on both l-tyrosine and l-dopa, and it showed broad substrate specificity. 相似文献
48.
Tero Huhtiniemi Tiina Suuronen Maija Lahtela-Kakkonen Tanja Bruijn Sanna Jääskeläinen Antti Poso Antero Salminen Jukka Leppänen Elina Jarho 《Bioorganic & medicinal chemistry》2010,18(15):5616-5625
Sirtuins catalyze the NAD+ dependent deacetylation of Nε-acetyl lysine residues to nicotinamide, O′-acetyl-ADP-ribose (OAADPR) and Nε-deacetylated lysine. Here, an easy-to-synthesize Ac-Ala-Lys-Ala sequence has been used as a probe for the screening of novel Nε-modified lysine containing inhibitors against SIRT1 and SIRT2. Nε-Selenoacetyl and Nε-isothiovaleryl were the most potent moieties found in this study, comparable to the widely studied Nε-thioacetyl group. The Nε-3,3-dimethylacryl and Nε-isovaleryl moieties gave significant inhibition in comparison to the Nε-acetyl group present in the substrates. In addition, the studied Nε-alkanoyl, Nε-α,β-unsaturated carbonyl and Nε-aroyl moieties showed that the acetyl binding pocket can accept rather large groups, but is sensitive to even small changes in electronic and steric properties of the Nε-modification. These results are applicable for further screening of Nε-acetyl analogues. 相似文献
49.
50.
EARLY RESPONSIVE TO DEHYDRATION 15, a negative regulator of abscisic acid responses in Arabidopsis
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EARLY RESPONSIVE TO DEHYDRATION 15 (ERD15) is rapidly induced in response to various abiotic and biotic stress stimuli in Arabidopsis (Arabidopsis thaliana). Modulation of ERD15 levels by overexpression or RNAi silencing altered the responsiveness of the transgenic plants to the phytohormone abscisic acid (ABA). Overexpression of ERD15 reduced the ABA sensitivity of Arabidopsis manifested in decreased drought tolerance and in impaired ability of the plants to increase their freezing tolerance in response to this hormone. In contrast, RNAi silencing of ERD15 resulted in plants that were hypersensitive to ABA and showed improved tolerance to both drought and freezing, as well as impaired seed germination in the presence of ABA. The modulation of ERD15 levels not only affected abiotic stress tolerance but also disease resistance: ERD15 overexpression plants showed improved resistance to the bacterial necrotroph Erwinia carotovora subsp. carotovora accompanied with enhanced induction of marker genes for systemic acquired resistance. We propose that ERD15 is a novel mediator of stress-related ABA signaling in Arabidopsis. 相似文献