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排序方式: 共有271条查询结果,搜索用时 15 毫秒
261.
The effect of anti- Paramoeba antibodies produced in sheep on Paramoeba sp., the causative agent of amoebic gill disease (AGD), was tested. Incubation of Paramoeba sp. with antiserum at a concentration of 20% or more effectively coated the Paramoeba with antibodies. The antiserum had no effect on Paramoeba sp. survival in vitro or on its ability to cause AGD in Atlantic salmon. 相似文献
262.
Confirmed congenital sarcocystosis has been reported extremely rarely in domestic ruminants. Sarcocystosis was diagnosed in a stillborn lamb with microscopic lesions predominantly in the central nervous system and placenta. Encephalitis was characterized by multiple foci of glial nodules some with central necrosis, perivascular cuffing and vascular occlusion, while placental lesions consisted of multifocal necroses, inflammation and mild calcification. Immature and mature schizonts were found in vascular endothelium of several organs. It is suggested that the protozoa were Sarcocystis tenella based on their morphology, location and as this is the most pathogenic Sarcocystis sp. parasitizing sheep. 相似文献
263.
264.
Striped trumpeter, Latris lineata, are being experimentally cultured by the Tasmanian Aquaculture and Fisheries Institute at Taroona, Tasmania. Fish surviving over 30 days post-hatching have frequently developed nervous aberrations associated with a severe granulomatous meningoencephalomyelitis. The myxozoan parasite Pentacapsula neurophila sp.n. was revealed as the parasite causing the disease in the striped trumpeter juveniles. Measurements made of isolated spores indicated that the organism was distinct from all previously described Pentacapsula species. This is the first report of a marine myxozoan parasite of the genus Pentacapsula in Australian waters. 相似文献
265.
E Jiménez‐Trigos C Naturil‐Alfonso JS Vicente F Marco‐Jiménez 《Reproduction in domestic animals》2013,48(1):15-19
The aim of this study was to investigate the effect of Taxol and Cytochalasin B on the spindle, chromosome configuration and development to blastocyst stage after parthenogenesis activation of in vivo matured rabbit oocytes after vitrification. Oocytes were randomized into four groups: oocytes treated with Cytochalasin B or Taxol before vitrification, oocytes without treatment before vitrification and fresh oocytes. Oocytes were vitrified using Cryotop method, and meiotic spindle and chromosomal distribution were assessed with a confocal laser scanning microscopy. To determine oocyte competence, in vitro development of oocytes was assessed with parthenogenesis activation. There were no significant differences in the frequencies of normal spindle (33.0%, 31.0% and 32.6%, for non‐treated, Taxol‐treated and Cytochalasin B‐treated oocytes, respectively) and chromosome (48.3%, 46.6% and 34.8%, for non‐treated, Taxol‐treated oocytes and Cytochalasin B‐treated oocytes respectively) in vitrified groups, but significantly lower than those of fresh group (89.7% and 90.2%, for normal spindle and chromosome organization, respectively). No statistical differences were found in the cleavage and blastocyst development rates between non‐treated and Taxol‐treated oocytes (7.7% and 1.5% and 13.7% and 4.6%, for non‐treated and Taxol‐treated oocytes, respectively), although they were significantly lower than in the fresh group (42.3% and 32.1%, for cleavage and blastocyst development, respectively). Oocytes treated with Cytochalasin B failed to reach blastocyst stage. Normal spindle, chromosome configuration and blastocyst development of in vivo matured rabbit oocytes were damaged in vitrification, which was not improved by Taxol and Cytochalasin B pre‐treatment before vitrification. Moreover, a detrimental effect on blastocyst development of Cytochalasin B pre‐treatment before vitrification was observed. 相似文献
266.
267.
AIMS: To study the adhesion properties of a biotype 4, serotype O:3 (human pathogenic) strain of Yersinia enterocolitica and to determine if adhesion in vitro and colonisation in vivo can be prevented by competition with a biotype 1A, serotype O:6,30 (non-pathogenic) strain. To study interaction between Y. enterocolitica biotype 4, serotype O:3 and cultured epithelial cells using the synthetic tripeptide arginine-glycine-aspartic acid (RGD). METHODS: The human intestinal epithelial (HEp-2) cell line was used for in vitro studies. Inocula of Y. enterocolitica biotype 4, serotype O:3 radiolabelled using tritium were incubated with HEp-2 cells and RGD tripeptide, or with Y. enterocolitica biotype 1A, serotype O:6,30 sequentially or concurrently, then washed and lysed, and radioactivity measured to determine the effect of RGD on adhesion, and competitive exclusion of pathogenic by non-pathogenic bacteria. For in vivo studies, two groups of 5-week-old piglets (n=5/group) were sequentially inoculated orally with 5x109 colony forming units (cfu) of either a non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica followed by a pathogenic biotype 4, serotype O:3 strain, or vice versa. Pigs were monitored for carriage of strains using bacterial culture and a multiplex polymerase chain reaction (PCR). RESULTS: The RGD tripeptide significantly inhibited adherence of the pathogenic Y. enterocolitica strain to cultured epithelial cells, suggesting that adhesion involved the RGD tripeptide sequence. The non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica prevented adhesion of the pathogenic strain to cells in vitro when allowed to adhere first. Pathogenic Y. enterocolitica was consistently isolated from rectal swabs from 80-100% of pigs on all sampling occasions but not from oral swabs after 14 days in pigs first inoculated with the non- pathogenic strain or at 26 days in pigs first inoculated with the pathogenic strain. CONCLUSIONS: A non-pathogenic strain of Y. enterocolitica reduced adhesion of a human pathogenic strain in vitro but not in vivo. 相似文献
268.
DR Stewart D Sprinzak CM Marcus CI Duruoz JS Harris 《Science (New York, N.Y.)》1997,278(5344):1784-1788
The ground and excited state spectra of a semiconductor quantum dot with successive electron occupancy were studied with linear and nonlinear magnetoconductance measurements. A direct correlation was observed between the mth excited state of the N-electron system and the ground state of the (N + m)-electron system for m up to 4. The results are consistent with a single-particle picture in which a fixed spectrum of energy levels is successively filled, except for a notable absence of spin degeneracy. Further departures from the single-particle picture due to electron-electron interaction were also observed. Magnetoconductance fluctuations of ground states show anticrossings where wave function characteristics are exchanged between adjacent levels. 相似文献
269.
ER Weeks Y Tian JS Urbach K Ide HL Swinney M Ghil 《Science (New York, N.Y.)》1997,278(5343):1598-1601
The mid-latitude atmosphere is dominated by westerly, nearly zonal flow. Occasionally, this flow is deflected poleward by blocking anticyclones that persist for 10 days or longer. Experiments in a rotating annulus used radial pumping to generate a zonal jet under the action of the Coriolis force. In the presence of two symmetric ridges at the bottom of the annulus, the resulting flows were nearly zonal at high forcing or blocked at low forcing. Intermittent switching between blocked and zonal patterns occurs because of the jet's interaction with the topography. These results shed further light on previous atmospheric observations and numerical simulations. 相似文献
270.
Inherited diseases of Australian Holstein-Friesian cattle 总被引:1,自引:1,他引:0