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451.
452.
John Gilmour 《BMJ (Clinical research ed.)》1927,1(3450):320.2-323
453.
454.
A number of plating and enrichment media proposed for the isolation of Yersinia enterocolitica from foodstuffs were examined for their ability to recover the type strains of Y. enterocolitica sensu stricto, Y. intermedia, Y. frederiksenii and Y. kristensenii. Nine selective plating media were evaluated for the quantitative recovery of the type strains in pure culture, and their inhibition of other organisms typical of both milk and enteric microfloras. Cefsulodin-irgasan-novobiocin (CIN) agar, incubated for 48 h at 25 degrees C, allowed a high recovery of all the Yersinia spp. and was the most selective medium. The same four type strains were added to UHT milk that had been previously inoculated with bacteria to simulate either freshly drawn or cold stored milk microfloras. Twenty-six enrichment procedures (including cold enrichment, selective enrichment at higher temperatures, two-step procedures and a post-enrichment alkali treatment) were assessed for the efficiency of recovery of the Yersinia spp. Pre-enrichment in trypticase-soy broth (TSB) for 24 h at 22 degrees C followed by selective enrichment in bile-oxalate-sorbose (BOS) medium for 5 d at 22 degrees C and plating on CIN agar (48 h at 25 degrees C) allowed the greatest increase in the numbers of Yersinia spp. and maximum inhibition of the competing microflora. 相似文献
455.
Steve F. Perry Marvin H. Braun Janet Genz Branka Vulesevic Josi Taylor Martin Grosell Kathleen M. Gilmour 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(8):1213-1225
The plainfin midshipman (Porichthys notatus) possesses an aglomerular kidney and like other marine teleosts, secretes base into the intestine to aid water absorption.
Each of these features could potentially influence acid–base regulation during respiratory acidosis either by facilitating
or constraining HCO3
− accumulation, respectively. Thus, in the present study, we evaluated the capacity of P. notatus to regulate blood acid–base status during exposure to increasing levels of hypercapnia (nominally 1–5% CO2). Fish exhibited a well-developed ability to increase plasma HCO3
− levels with values of 39.8 ± 2.8 mmol l−1 being achieved at the most severe stage of hypercapnic exposure (arterial blood PCO2 = 21.9 ± 1.7 mmHg). Consequently, blood pH, while lowered by 0.15 units (pH = 7.63 ± 0.06) during the final step of hypercapnia,
was regulated far above values predicted by chemical buffering (predicted pH = 7.0). The accumulation of plasma HCO3
− during hypercapnia was associated with marked increases in branchial net acid excretion (J
NETH+) owing exclusively to increases in the titratable alkalinity component; total ammonia excretion was actually reduced during
hypercapnia. The increase in J
NETH+ was accompanied by increases in branchial carbonic anhydrase (CA) enzymatic activity (2.8×) and CA protein levels (1.6×);
branchial Na+/K+-ATPase activity was unaffected. Rectal fluids sampled from control fish contained on average HCO3
− concentrations of 92.2 ± 4.8 mmol l−1. At the highest level of hypercapnia, rectal fluid HCO3
− levels were increased significantly to 141.8 ± 7.4 mmol l−1 but returned to control levels during post-hypercapnia recovery (96.0 ± 13.2 mmol l−1). Thus, the impressive accumulation of plasma HCO3
− to compensate for hypercapnic acidosis occurred against a backdrop of increasing intestinal HCO3
− excretion. Based on in vitro measurements of intestinal base secretion in Ussing chambers, it would appear that P. notatus did not respond by minimizing base loss during hypercapnia; the increases in base flux across the intestinal epithelium in
response to alterations in serosal HCO3
− concentration were similar in preparations obtained from control or hypercapnic fish. Fish returned to normocapnia developed
profound metabolic alkalosis owing to unusually slow clearance of the accumulated plasma HCO3
−. The apparent inability of P. notatus to effectively excrete HCO3
− following hypercapnia may reflect its aglomerular (i.e., non-filtering) kidney coupled with the normally low rates of urine
production in marine teleosts. 相似文献
456.
Yersinia enterocolitica and Y. enterocolitica -like bacteria were frequently isolated from samples of both raw bulked milk (34/150) and farm bottled (raw) milk (5/20). These bacteria were also found to contaminate creamery pasteurized milk (6/100 samples) and farm pasteurized milk (4/50 samples). Although Y. enterocolitica was the most commonly isolated species, Y. intermedia and Y. frederiksenii were also frequently obtained (52, 31 and 15% of isolates, respectively). Also, one atypical strain was identified as Y. aldovae . The Y. enterocolitica strains were largely biotype 1 (20/27) including five strains which could ferment lactose. One third of the Y. enterocolitica strains were not typable, but of those which were, the serotypes were 0:34 (18.5%), 0:5,27 (18.5%), 0:6,30 (15%), 0:4 (11%) and 0:7 (4%). Pre-enrichment in trypticase-soy broth (TSB) (at 22°C for 24 h) followed by selective enrichment in bile-oxalate-sorbose broth (at 22°C for 6 d) allowed the recovery of 92.3% of all isolates, as compared with 15.4% using cold enrichment in TSB at 4°C for 21 d. 相似文献
457.
S Gilmour J Randall J Torbet R A Dwek S Wain-Hobson S K Dower M R van Schravendijk 《Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain)》1981,211(1185):433-453
The first small-angle scattering study of an immunoglobulin A is reported. Neutron measurements have been made to determine conformational parameters of the mouse myeloma protein MOPC315 and to relate these to previous immunoglobulin G results. Use of the contrast method shows that the MOPC315 IgA molecule is not simply globular, that it has a dry volume of 220.0 +/- 4.5 nm3 corresponding to a mass density of 1.275 +/- 0.025 g cm-3 and that its full and cross-sectional radii of gyration, corrected for concentration dependence, are 7.97 +/- 0.07 nm, 2.40 +/- 0.08 nm and 1.33 +/- 0.07 nm respectively. Similar study of its Fab fragment gives a dry molecular volume of 69.0 +/- 0.7 nm3, a mass density of 1.285 +/- 0.015 g cm-3 and uncorrected radii of gyration that are consistent with those of the parent and support an overall "T" or "Y" conformation in solution. Addition to saturation of a small monovalent dinitrophenyl hapten leaves the dry volume of the whole molecule unaltered, but may slightly lower one or more of its radii of gyration. The significance of this finding is discussed. Comparative studies with rabbit anti-dinitrophenyl immunoglobulin G antibody suggest a different initial conformation but similar consequences of hapten binding, which, if real, are probably unrelated to classical complement fixation. 相似文献
458.
The abilities of two races of Arabidopsis thaliana L. (Heyn), Landsberg erecta and Columbia, to cold harden were examined. Landsberg, grown at 22 to 24°C, increased in freezing tolerance from an initial 50% lethal temperature (LT50) of about −3°C to an LT50 of about −6°C after 24 hours at 4°C; LT50 values of −8 to −10°C were achieved after 8 to 9 days at 4°C. Similar increases in freezing tolerance were obtained with Columbia. In vitro translation of poly(A+) RNA isolated from control and cold-treated Columbia showed that low temperature induced changes in the population of translatable mRNAs. An mRNA encoding a polypeptide of about 160 kilodaltons (isoelectric point about 4.5) increased markedly after 12 to 24 h at 4°C, as did mRNAs encoding four polypeptides of about 47 kilodaltons (isoelectric points ranging from 5-5.5). Incubation of Columbia callus tissue at 4°C also resulted in increased levels of the mRNAs encoding the 160 kilodalton polypeptide and at least two of the 47 kilodalton polypeptides. In vivo labeling experiments using Columbia plants and callus tissue indicated that the 160 kilodalton polypeptide was synthesized in the cold and suggested that at least two of the 47 kilodalton polypeptides were produced. Other differences in polypeptide composition were also observed in the in vivo labeling experiments, some of which may be the result of posttranslational modifications of the 160 and 47 kilodalton polypeptides. 相似文献
459.
Four enzyme activities catalyzing the following oxidative steps in the gibberellin (GA) biosynthetic pathway have been extracted from spinach (Spinacia oleracea L.) leaves after exposure to 8 long days: GA12 → GA53 → GA44 → GA19 → GA20. Two of these, GA53 oxidase and GA19 oxidase, were separable from the other two, GA44 oxidase and GA12 13-hydroxylase, by anion exchange high performance liquid chromatography (HPLC). Apparent molecular weights of the four enzymes as determined by gel filtration HPLC are: GA12 13-hydroxylase, 28,400; GA53 oxidase, 42,500; GA44 oxidase, 38,100; GA19 oxidase, 39,500. GA44 oxidase was purified approximately 100-fold in 0.3% yield by a combination of ammonium sulfate fractionation, anion exchange HPLC, phenyl-Sepharose chromatography and gel filtration HPLC. 相似文献
460.
Spray Clive Phinney Bernard O. Gaskin Paul Gilmour Sarah J. MacMillan Jake 《Planta》1984,160(5):464-468
[13C, 3H]Gibberellin A20 (GA20) has been fed to seedlings of normal (tall) and dwarf-5 and dwarf-1 mutants of maize (Zea mays L.). The metabolites from these feeds were identified by combined gas chromatography-mass spectrometry. [13C, 3H]Gibberellin A20 was metabolized to [13C, 3H]GA29-catabolite and [13C, 3H]GA1 by the normal, and to [13C, 3H]GA29 and [13C, 3H]GA1 by the dwarf-5 mutant. In the dwarf-1 mutant, [13C, 3H]GA20 was metabolized to [13C, 3H]GA29 and [13C, 3H]GA29-catabolite; no evidence was found for the metabolism of [13C, 3H]GA20 to [13C, 3H]GA1. [13C, 3H]Gibberellin A8 was not found in any of the feeds. In all feeds no dilution of 13C in recovered [13C, 3H]GA20 was observed. Also in the dwarf-5 mutant, the [13C]label in the metabolites was apparently undiluted by endogenous [13C]GAs. However, dilution of the [13C]label in metabolites from [13C, 3H]GA20 was observed in normal and dwarf-1 seedlings. The results from the feeding studies provide evidence that the dwarf-1 mutation of maize blocks the conversion of GA20 to GA1.Abbreviations GAn
gibberellin An
- GC-MS
combined gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
- RP
reverse phase 相似文献