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Isolation of Aeromonas caviae from ice-cream 总被引:1,自引:0,他引:1
Sixty-four samples of ice-cream were examined for the presence of Aeromonas species. Culture was by direct inoculation onto xylose deoxycholate citrate agar and into alkaline peptone water. Aeromonas caviae was isolated from three of the 64 samples (4–7%). The potential pathogenic significance of this organism in ice-cream is discussed. 相似文献
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BRYANT SUSAN V.; HOLDER NIGEL; TANK PATRICK W. 《Integrative and comparative biology》1982,22(1):143-151
SYNOPSIS. A current model concerning the process of limb regenerationin vertebrates is examined. According to this model (Bryantet al, 1981), new positional values in the proximal-distal limbaxis are laid down as a result of local interactions betweencells in the limb circumference. Cells with disparate circumferentialpositional values come together at the site of future outgrowthand intercalation between them generates more distal levelsof the pattern. The results of a number of experiments on surgicallycreated symmetrical limb stumps are discussed in relation tothis model. In addition, an extension of this model to accountfor digit formation is presented, and the implications of thisformulation for limb evolution are discussed. 相似文献
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SUSAN SEYMOUR 《American anthropologist》2006,108(3):570-571
A Companion to Psychological Anthropology. Conerly Casey and Robert B. Edgerton, eds. Williston, VT: Blackwell Publishers, 2005. 523 pp. 相似文献
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Rate of trypanosome killing by lectins in midguts of different species and strains of Glossina 总被引:4,自引:0,他引:4
The activity of lectins in different species of tsetse was compared in vivo by the time taken to remove all trypanosomes from the midgut following an infective feed and in vitro by agglutination tests. Teneral male Glossina pallidipes Austen, G. austeni Newstead and G. p. palpalis R-D. removed 50% of all Trypanosoma brucei rhodesiense Stephens & Fantham infections within 60 h. A 'refractory' line of G. m. morsitans Westwood took 170 h to kill 50% infections while a 'susceptible' line of the same species failed to kill 50%. Agglutination tests with midgut homogenates showed differences between fly stocks which accorded with differences in rate of trypanosome killing in vivo. Flies fed before an infective feed were able to remove trypanosomes from their midguts more quickly than flies infected as tenerals. Increasing the period of starvation before infection increased the susceptibility to trypanosome infection of non-teneral flies. Teneral flies showed little agglutinating activity in vitro, suggesting that lectin is produced in response to the bloodmeal. Feeding flies before infection also abolished the differences in rate of trypanosome killing found between teneral 'susceptible' and 'refractory' G. m. morsitans, suggesting that maternally inherited susceptibility to trypanosome infection is a phenomenon limited to teneral flies. Electron micrographs of midguts of G. m. morsitans suggest that procyclic trypanosomes are killed by cell lysis, presumably the result of membrane damage caused by lectin action. 相似文献
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Data from bioassays of field collected aphids, barley indicator plants exposed to natural conditions, and various types of aphid traps were used to describe the spread of barley yellow dwarf virus (BYDV) in wheat and barley near Prosser, Washington. Bioassays were also used to assess the relative importance of local vector species. Of alate aphids collected from grain in the 1982 and 1983 fall migration seasons, 3.4–14–5% transmitted BYDV. Data from concurrent and post-migration assays of resident aphids (apterae and nymphs) reflected an increase in the proportion of infected plants in the field. Maximum increase in the percentage of viruliferous aphids occurred in late November and December of 1982 and November of 1983. The 1982 increase occurred after aphid flights had ceased for the year, suggesting active secondary spread. Collections in pitfall traps and infected trap plants from November to February confirmed aphid activity and virus spread. Rhopalosiphum padi was the most important vector in central Washington in 1982 and 1983 because of its abundance and relative BYDV transmission efficiency. Metopolophium dirhodum was more winter-hardy than R. padi and equal to R. padi in its efficiency as a vector; however, it was not as abundant as R. padi except during the mild winter of 1982–83, when it was a major contributor to secondary spread. Sitobion avenae may be important in years when it is abundant, but it was only a quarter as efficient as R. padi. Rhopalosiphum maidis was a much less efficient vector than R. padi and it only reached high populations in late autumn barley. 相似文献
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A mechanically transmissible virus obtained from symptomless plants of a red raspberry selection imported into Scotland from Quebec, Canada was indistinguishable serologically from a cherry isolate of cherry rasp leaf virus (CRLV). The raspberry isolate, CRLV-R, was graft transmitted to several virus indicator species and cultivars of Rubus without inducing noticeable symptoms. In Chenopodium quinoa sap, CRLV-R lost infectivity after dilution to 10-5 or heating for 10 min at 60°C but was infective after 16 days (the longest period tested) at 18°, 4° or - 15°C. The virus particles are isometric, c. 28 nm in diameter, and were purified with difficulty from infected C. murale and C. quinoa plants. The particles comprise two nucleoprotein components with sedimentation coefficients of 89 and 115 S and are prone to aggregate during purification. When centrifuged to equilibrium in CS2SO4 solution, purified virus preparations formed two major components with p= 1·28 and 1·36 g/cm3. Virus particles contained two RNA species which, when denatured in glyoxal and electrophoresed in agarose gels, had estimated mol. wt of 2·56 × 106 (RNA-1) and 1·26 × 106 (RNA–2). Infectivity of CRLV-R RNA was abolished by treatment with proteinase K, suggesting that the RNA is linked to protein necessary for infectivity; RNA molecules contained polyadenylate. In reticulocyte lysates, CRLV-R RNA stimulated the incorporation of 3H-leucine, mainly into two polypeptides of estimated mol. wt 200 000 and 102 000. When electrophoresed in polyacrylamide gels, protein obtained from CRLV-R particles purified by centrifugation to equilibrium in Cs2SO4 separated into three bands with estimated mol. wt 26 000 , 23 000 and 21 000. 相似文献
10.
F. MARCIANO-CABRAL SUSAN STANITSKI V. RADHAKRISHNA S. G. BRADLEY 《The Journal of eukaryotic microbiology》1987,34(2):146-149
An intracellular alpha-aminoacyl-peptide hydrolase (EC 3.4.11.-) from Naegleria fowteri nN68 (ATCC 30894) has been characterized. The enzyme preparation hydrolyzed phenylalanyl-, tyrosyl-, leucyl-, arginyl-, alanyl-, tryptophanyl-, histidyl-, methionyl-, and lysyl-naphthylamide but not benzoylleucyl-, leucylglycyl-, glycylprolylleucyl-, glycyl-, threonyl-, aspartyl-, or glutamyl-naphthylamide. The aminopeptidase activity was inhibited by the cysteine-protease inhibitors—hydroxymercuribenzoate, chloromercurisulfate, and iodoacetate- by the aminopeptidase inhibitors-bestatin and trans-epoxysuccinyl-leucyl-agmatine- by an inhibitor of soluble alanyl aminopeptidase EC 3.4.11.14, puromycin, and by the metalloprotease inhibitor, o-phenanthroline. The exopeptidase activity was not inhibited by the chelator, ethylenediaminetetraacetate, or the serine-protease inhibitor, phenylmethylsulfonylfluoride. The pH optimum of the exopeptidase was between 7.0 and 8.0. Enzyme activity was stable at 55°C for 30 min, but all activity was lost after 15 min at 80°C. Enzyme activity was inhibited by 100 μM HgCI2 and CdCl2 but not by 1 mM CoCl2 , CuCl2 , MnCl2 , NiCl2 , FeCl2 , or ZnCl2 . Enzyme activity was inhibited by 0.1% sodium dodecyl sulfate but not by 0.2% Brij 35, Tween 20, Tween 80, or Triton X-100. 相似文献