Conformational switches modulate protein interactions in peptide antibiotic synthetases     

Koglin A  Mofid MR  Löhr F  Schäfer B  Rogov VV  Blum MM  Mittag T  Marahiel MA  Bernhard F  Dötsch V 《Science (New York, N.Y.)》2006,312(5771):273-276

Protein dynamics plays an important role in protein function. Many functionally important motions occur on the microsecond and low millisecond time scale and can be characterized by nuclear magnetic resonance relaxation experiments. We describe the different states of a peptidyl carrier protein (PCP) that play a crucial role in its function as a peptide shuttle in the nonribosomal peptide synthetases of the tyrocidine A system. Both apo-PCP (without the bound 4'-phosphopantetheine cofactor) and holo-PCP exist in two different stable conformations. We show that one of the apo conformations and one of the holo conformations are identical, whereas the two remaining conformations are only detectable by nuclear magnetic resonance spectroscopy in either the apo or holo form. We further demonstrate that this conformational diversity is an essential prerequisite for the directed movement of the 4'-PP cofactor and its interaction with externally acting proteins such as thioesterases and 4'-PP transferase.  相似文献   

Cost-benefit tradeoffs in engineered lac operons     

Eames M  Kortemme T 《Science (New York, N.Y.)》2012,336(6083):911-915

Cells must balance the cost and benefit of protein expression to optimize organismal fitness. The lac operon of the bacterium Escherichia coli has been a model for quantifying the physiological impact of costly protein production and for elucidating the resulting regulatory mechanisms. We report quantitative fitness measurements in 27 redesigned operons that suggested that protein production is not the primary origin of fitness costs. Instead, we discovered that the lac permease activity, which relates linearly to cost, is the major physiological burden to the cell. These findings explain control points in the lac operon that minimize the cost of lac permease activity, not protein expression. Characterizing similar relationships in other systems will be important to map the impact of cost/benefit tradeoffs on cell physiology and regulation.  相似文献   

Clinical Course of Acute Canine Polyradiculoneuritis Following Treatment with Human IV Immunoglobulin     

K Hirschvogel  K Jurina  TA Steinberg  LA Matiasek  K Matiasek  E Beltrán  A Fischer 《Journal of the American Animal Hospital Association》2012,48(5):299-309

Treatment of dogs with acute canine polyradiculoneuritis (ACP) is restricted to physical rehabilitation and supportive care. In humans with Guillain-Barré syndrome, the counterpart of ACP, randomized trials show that IV immunoglobulin (IVIg) speeds recovery. The authors of the current study hypothesized that dogs with ACP would tolerate IVIg well and recover faster than dogs managed with supportive treatment only. Sixteen client-owned dogs with ACP were treated with IVIg, and 14 client-owned dogs served as a retrospective control group. Diagnosis was confirmed using clinical features, electrodiagnostics, cerebrospinal fluid analysis, and muscle/nerve biopsies. The duration of the initial progressive phase, the time from IVIg administration until the dogs were ambulating without assistance, and the duration of the complete episode were evaluated. Adverse reactions (anaphylaxis, mild hematuria) were observed in two dogs. Dogs treated with IVIg were ambulating without assistance after a median of 27.5 days (range, 15-127 days) from onset of clinical signs. The control group was ambulatory without assistance at a median of 75.5 days (range, 5-220 days). Even though this result is not statistically significant, there is a clear trend toward faster recovery in dogs treated with IVIg.  相似文献   

Vaccination with inactivated or live-attenuated chimeric PCV1-2 results in decreased viremia in challenge-exposed pigs and may reduce transmission of PCV2     

Hemann M  Beach NM  Meng XJ  Halbur PG  Opriessnig T 《Veterinary microbiology》2012,158(1-2):180-186

The objectives were to determine transmissibility of PCV2 to na?ve contact pigs 140 days after infection of resident pigs and the benefit of vaccination with live-attenuated or inactivated chimeric PCV2 vaccines on chronic PCV2 infection. Twelve 6-week old PCV2 na?ve pigs were randomly divided into four groups of three pigs: negative controls, positive controls, and pigs vaccinated with either a live-attenuated or inactivated chimeric PCV1-2 vaccine. All animals were bled weekly and tested for anti-PCV2 antibodies and PCV2 and PCV1-2 DNA and all groups except negative controls were challenged at 10 weeks. Two pigs vaccinated with the live PCV2 vaccine were PCV1-2 viremic at a single observation point. Both vaccine regimens induced an anti-PCV2 antibody response which was detected sooner and reached a higher level with the commercial inactivated vaccine. Both vaccines significantly decreased the concentration and duration of PCV2 viremia compared to the positive controls. PCV2 DNA was detected in lymphoid tissues of 1/3 pigs in the live-attenuated vaccine group and 3/3 positive control pigs. Three, 2-week old, PCV2 na?ve contact pigs were comingled with each group at 168 days post-vaccination or 140 days post-challenge. After seven days of co-housing, the resident pigs were removed and the contact pigs remained for six weeks. Evidence of chimeric PCV1-2 vaccine or PCV2 challenge virus transmission to na?ve contact pigs was lacking in all groups. The results of this study suggest that 140-day closure of a small pig population in a controlled environment may result in stabilization and elimination of PCV2.  相似文献   

Integrated standardization concept for Angelica botanicals using quantitative NMR     

Gödecke T  Yao P  Napolitano JG  Nikolić D  Dietz BM  Bolton JL  van Breemen RB  Farnsworth NR  Chen SN  Lankin DC  Pauli GF 《Fitoterapia》2012,83(1):18-32

Despite numerous in vitro/vivo and phytochemical studies, the active constituents of Angelica sinensis (AS) have not been conclusively identified for the standardization to bioactive markers. Phytochemical analyses of AS extracts and fractions that demonstrate activity in a panel of in vitro bioassays, have repeatedly pointed to ligustilide as being (associated with) the active principle(s). Due to the chemical instability of ligustilide and related issues in GC/LC analyses, new methods capable of quantifying ligustilide in mixtures that do not rely on an identical reference standard are in high demand. This study demonstrates how NMR can satisfy the requirement for simultaneous, multi-target quantification and qualitative identification. First, the AS activity was concentrated into a single fraction by RP-solid-phase extraction, as confirmed by an alkaline phosphatase, (anti-)estrogenicity and cytotoxicity assay. Next, a quantitative ¹H NMR (qHNMR) method was established and validated using standard compounds and comparing processing methods. Subsequent 1D/2D NMR and qHNMR analysis led to the identification and quantification of ligustilide and other minor components in the active fraction, and to the development of quality criteria for authentic AS preparations. The absolute and relative quantities of ligustilide, six minor alkyl phthalides, and groups of phenylpropanoids, polyynes, and poly-unsaturated fatty acids were measured by a combination of qHNMR and 2D COSY. The qNMR approach enables multi-target quality control of the bioactive fraction, and enables the integrated biological and chemical standardization of AS botanicals. This methodology can potentially be transferred to other botanicals with active principles that act synergistically, or that contain closely related and/or constituents, which have not been conclusively identified as the active principles.  相似文献   

Limited susceptibility of three different mouse (Mus musculus) lines to Porcine circovirus-2 infection and associated lesions          下载免费PDF全文

Tanja Opriessnig  Abby R. Patterson  Douglas E. Jones  Nicole M. Juhan  Xiang-Jin Meng    Patrick G. Halbur 《Canadian journal of veterinary research》2009,73(2):81-86

Porcine circovirus associated disease (PCVAD), a major global problem for pork producers, is characterized microscopically by depletion and histiocytic replacement of follicles in the lymphoid tissues. The objectives of this study were to determine 1) if Porcine circovirus-2 (PCV-2) inoculated mice (Mus musculus) can develop PCV-2 associated lymphoid lesions and serve as a model for PCVAD, and 2) if differences in PCV-2 host susceptibility exist among mice lines. Three groups (n = 48/group) of 4-wk-old male mice were used: BALB/c, C57BL/6, and C3H/HeJ. A 2 × 2 factorial analysis was designed for each group using PCV-2 inoculation and keyhole limpet hemocyanin in incomplete Freund’s adjuvant injections on day 0 and 7 as factors. Necropsies were performed on days 12, 17, 22, 27, 32, and 37. Serum samples collected at each necropsy tested negative for anti-IgG PCV-2 antibodies in all mice at all time points by 2 different PCV-2 enzyme-linked immunosorbent assays (ELISA). The PCV-2 DNA was detected by polymerase chain reaction (PCR) in 93% (100/108) of tissues and 42.6% (46/108) of serum samples from PCV-2-inoculated mice from days 12 to 37. Microscopic lesions consistent with PCV-2 infection were not observed in any mice and PCV-2 DNA and PCV-2 antigen were not detected in tissues by in-situ-hybridization or immunohistochemistry assays, respectively. Based on incidence of PCV-2 DNA in serum samples, the C57BL/6 mouse line was more resistant to PCV-2 infection than the other lines. The results indicate the mouse model likely has limited utility to advance understanding of the pathogenesis of PCV-2 associated lesions, but mice could potentially be important in the epidemiology of PCV-2.  相似文献   

Infectivity of porcine circovirus type 2 DNA in semen from experimentally-infected boars   总被引：1，自引：0，他引：1  

Madson DM  Ramamoorthy S  Kuster C  Pal N  Meng XJ  Halbur PG  Opriessnig T 《Veterinary research》2009,40(1):10-Feb;40(1):10

Porcine circovirus type 2 (PCV2) is an economically important pathogen. It has been demonstrated that PCV2 DNA can be detected in boar semen by PCR; however, the biological relevance of this is unknown. The objectives of this study were to determine if semen positive for PCV2 DNA is infectious (1) in a swine bioassay, or (2) when used for artificial insemination. For the first objective, 4-week-old pigs were inoculated intraperitoneally with PCV2 DNA-negative (bioassay-control; n = 3), PCV2a DNA-positive (bioassay-PCV2a; n = 3), or PCV2b DNA-positive (bioassay-PCV2b; n = 3) raw semen, or PCV2 live virus (bioassay-positive; n = 3), respectively. Pigs inoculated with PCV2 DNA-positive semen and PCV2 live virus became viremic and developed anti-PCV2 antibodies indicating that the PCV2 DNA present in semen was infectious. For the second objective, three Landrace gilts were inseminated with PCV2 DNA-negative semen (gilts-controls) from experimentally-infected boars, and six gilts were artificially inseminated with semen positive for PCV2a DNA (gilts-PCV2a; n = 3) or PCV2b DNA (gilts-PCV2b; n = 3). Serum samples collected from the gilts in all groups remained negative for anti-PCV2 antibodies for the duration of the experiment. In addition, fetal serum samples from all 105-day-gestation fetuses were negative for anti-PCV2 antibodies or PCV2 DNA. Under the conditions of this study, PCV2 DNA-positive semen was not infectious when used to artificially inseminate gilts; however, it was demonstrated to be infectious in a swine bioassay model and therefore is a potential means of PCV2 transmission amongst swine herds.  相似文献   

Prevalence and radiologic and histologic appearance of vesicourachal diverticula in dogs without clinical signs of urinary tract disease     

Groesslinger K  Tham T  Egerbacher M  Lorinson D 《Journal of the American Veterinary Medical Association》2005,226(3):383-386

OBJECTIVE: To determine prevalence and radiologic and histologic appearance of vesicourachal diverticula in dogs without clinical signs of urinary tract disease. DESIGN: Original study. ANIMALS: 50 dogs between 4 months and 17 years old representing 22 breeds that had been euthanatized for unrelated reasons; none of the dogs had a history or clinical signs of urinary tract disease. PROCEDURE: Retrograde positive-contrast radiography was performed, and radiographs were examined for macroscopic diverticula. Necropsy specimens from the urinary bladder vertex were examined by means of light microscopy for diverticula and signs of inflammation. RESULTS: 17 of the 50 (34%) dogs had vesicourachal diverticula, and 1 additional dog had a urachal cyst. Fifteen of the 17 diverticula were macroscopic; surface area of the diverticulum could be measured radiographically in 13 of these dogs and ranged from 1 to 90 mm2. The remaining 2 diverticula were microscopic. Sixteen diverticula were intramural and 1 was extramural. Light microscopic signs of bladder wall inflammation could be detected in 5 dogs, 4 of which had macroscopic diverticula. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a high percentage of dogs without clinical signs of urinary tract disease may have vesicourachal [corrected] diverticula. Further studies are needed to determine the clinical relevance of vesicourethral diverticula in dogs.  相似文献   

Protein-losing enteropathy caused by Lawsonia intracellularis in a weanling foal          下载免费PDF全文

Bihr TP 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(1):65-66

A 5-month-old Morgan filly was presented to the Atlantic Veterinary College with a history of lethargy, fever, depression, anorexia, and dependent ventral edema. Diagnostic tests revealed severe inflammation, hypoproteinemia, and thickened small intestinal loops. Protein-losing enteropathy caused by Lawsonia intracellularis was diagnosed and treated successfully with erythromycin-rifampin.  相似文献   

Erysipelothrix rhusiopathiae septicemia in a Laughing kookaburra (Dacelo novaeguineae).     

T Opriessnig  R K Vance  P G Halbur 《Journal of veterinary diagnostic investigation》2005,17(5):497-499

Erysipelothrix rhusiopathiae (E. rhusiopathiae) septicemia was demonstrated in a captive Laughing kookaburra (Dacelo novaeguineae). The bird died after a 2-week period of weakness and weight loss. At necropsy, the bird was emaciated and had reddened and wet lungs. Microscopic lesions were limited to hepatic and pulmonary congestion with focal thrombosis. Erysipelothrix rhusiopathiae was isolated by routine bacterial culture from several organs. Further characterization of the isolate by pulsed-field gel electrophoresis indicated that the isolate has a new genotype pattern 3A(III), which is 91.7% homologous to an E. rhusiopathiae that was isolated from a pig in 2001 and 88% homologous to an isolate recovered in 2000 from a turkey with septicemia. This is the first report of E. rhusiopathiae-induced septicemia in a kookaburra.  相似文献