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Orwell Ralph L. Wood Ronald L. Tarran Jane Torpy Fraser Burchett Margaret D. 《Water, air, and soil pollution》2004,157(1-4):193-207
Water, Air, &; Soil Pollution - The quality of the indoor environment has become a major health consideration, since urban-dwellers spend 80-90% of their time indoors, where air pollution can be... 相似文献
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Akabane disease in sheep 总被引:1,自引:0,他引:1
Perinatal lamb mortality, associated with malformations of the CNS due to Akabane viral infection, occurred in 4 of 9 flocks of ewes lambing on 3 farms between 26 May and 14 November, 1976. Cases were restricted to ewes conceiving prior to the second week of March and lambing between 26 May and 19 July. As judged by seroconversion in sentinel flocks on 2 of the farms, field infection with Akabane virus occurred mainly between mid-February and mid-April. Malformations of the CNS occurred in 42.5%, 51.2%, 100% and 31.0% of the dead lambs examined in the affected flocks respectively. Prevalence in the 4 affected flocks, expressed as the proportion of ewes lambing which delivered at least one malformed foetus, was 6.1%, 8.4%, 88.9% and 5.7% respectively. Lamb mortality due to malformations of the CNS was 7.1%, 5.5%, 92.3% and 5.7% of lambs born. Age-specific prevalence was calculated for 3 of the 4 flocks and 2-year-old ewes accounted for 71.4% and 76.9% of total cases respectively in 2 flocks, whereas in one flock malformations occurred at equivalent frequencies throughout several older age groups. Birthweights of affected lambs were usually significantly lighter than those of unaffected lambs of similar sex and birth-type, and their mean duration of gestation was slightly, and significantly, prolonged. Micrencephaly (88.1% of cases) and hydrocephalus (68.7% of cases) were the outstanding pathological features of the malformations with hydranencephaly, microgyria, porencephaly and attenuation of the spinal cord occurring at much lower frequencies.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Plasmid transfer and plasmid-mediated genetic exchange in Brucella abortus. 总被引:2,自引:0,他引:2 下载免费PDF全文
Naturally-occurring plasmids and gene transfer mechanisms have not yet been reported in brucellae. Here we show that Brucella abortus is capable of maintaining and transferring the broad-host-range plasmids pTH10 (IncP), pSa (IncW) and R751 (IncP), and describe pTH10-mediated transfer of B. abortus chromosomal genes to Escherichia coli. All three plasmids transferred by conjugation from E. coli to B. abortus S19, and from B. abortus S19 to B. abortus 292 (biovar 4). They were stably maintained with no effect on biotyping characteristics. Plasmid pTH10 is a Tn1-containing derivative of RP4. It confers temperature-sensitive resistance to kanamycin, tetracycline and ampicillin to E. coli, but its tetracycline resistance and temperature sensitivity were poorly expressed in B. abortus. Plasmids pTH10 and pSa both transferred from B. abortus to E. coli DP50, a strain that is auxotrophic for diaminopimelic acid (DAP) Plasmid pTH10 (but not pSa) mobilized Brucella chromosomal gene(s) for DAP synthesis to DP50, yielding non-DAP-requiring (NDR) transconjugants. Neither plasmid transferred the NDR marker from their original E. coli host strains, nor did pTH10 transfer it from NDR transconjugants. Escherichia coli NDR transconjugant EP8.11 was cured of pTH10 by passage at the nonpermissive temperature, but retained the NDR marker and the Tn1-encoded resistance to ampicillin, indicating Tn1-mediated integration of Brucella chromosomal DNA into the E. coli chromosome. 相似文献
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