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排序方式: 共有421条查询结果,搜索用时 15 毫秒
1.
Melody L. Danley P. Brett Kenney Patricia M. Mazik Rodney Kiser Joseph A. Hankins 《Journal of the World Aquaculture Society》2005,36(3):249-261
Rainbow trout Oncorhynchus mykiss (261.6 × 24.7 g initial weight, mean × SEM) at 13.1 × 0.2 C were exposed for 94 d to one of three CO2 treatments: control (22.1 × 2.8 mg/L), medium (34.5 × 3.8 mg/L), or high (48.7 × 4.4 mg/L). Trout were checked daily for survival, and fish were sampled at 0, 28, 56, and 84 d for physiological responses, growth, and fillet quality assessments. Trout were also challenged to a 15-min crowding stress at 93 d to assess their ability to initiate a stress response during hypercapnia. Chronically exposed trout showed nearly 100% survival through 84 d exposure (1 of 1,500 fish died). Growth and physiological results showed that increasing elevated CO2 , concentrations result in corresponding decreased growth rates and CO2 specific physiological parameters: The medium and high CO2 treatments had significantly slower growth and subsequently smaller fish by 84 d. Exposed trout also showed significantly ( P < 0.05) decreased plasma chloride for medium and high CO2 treatments compared to the control from 28 through 84 d. Decreased growth and smaller fish in the medium and high CO2 treatments resulted in correspondingly smaller fresh and smoked fillet weights. Chronic CO2 exposure did not result in notable changes in ultimate muscle pH. Exposure to 15-min crowding stress at 93 d resulted in significant changes in hematocrit, plasma cortisoI, glucose, and chloride for all treatment groups. CO2 -specific changes were detected in hematocrit, plasma cortisoI, and plasma chloride responses following the 15-min crowding stress. 相似文献
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K. R. Everett I. P. S. Pushparajah O. E. Timudo A. Ah Chee R. W. A. Scheper P. W. Shaw T. M. Spiers J. T. Taylor D. R. Wallis P. N. Wood 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(2):367-383
Infection of Malus x domestica cv. Royal Gala fruit by Colletotrichum acutatum causing bitter rot was studied in the temperate climate of New Zealand. Temperatures above 15 °C were required for lesions to develop on detached apple wound-inoculated or inoculated without wounding with C. acutatum spores, regardless of maturity. A wetness period of 72 h was required for infection of mature detached apple fruit without wounding. On wound-inoculated detached apple fruits, sporulation was related to temperature and followed a similar pattern. In the field, a mean temperature above 15 °C for 72 h after wound-inoculation was required for lesions to develop. Buds were a more important source of inoculum than twigs, and it was shown that C. acutatum could be isolated more frequently from outer bud scales than from inner scales. Asymptomatic infection of vegetative and reproductive buds was detected. C. acutatum was detected on asymptomic surface-sterilised petals and fruit, more commonly during summer than spring. Symptomless sterilised leaves generally yielded C. acutatum throughout the season, but isolations were more frequent in summer. Recovery of inoculum using a splash meter to detect vertical dispersal showed that in summer inoculum was primarily splashed up from the ground. In spring, inoculum was recovered in similar quantities from all heights up to a metre, suggesting that splash dispersal occurs from the canopy as well as from the ground. A disease cycle for C. acutatum infecting apples and causing bitter rot in New Zealand is suggested. 相似文献
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John F. Leslie Kurt A. Zeller Melissa Wohler Brett A. Summerell 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(5-6):611-618
Gibberella fujikuroi and Gibberella intermedia(mating populations ‘C’ and ‘D’ of the G. fujikuroi species complex) can be distinguished by differences in the spectrum of mycotoxins produced, the lack of sexual cross-fertility and diagnostic differences in their DNA sequences. Some isolates from these two biological species, however, can interbreed and complete meiosis to produce viable progeny. Analysis of marker segregation amongst such hybrid progeny can be used to estimate the degree of genomic rearrangement and genetic incompatibility that has accumulated since these sibling species diverged. Recombinant progeny were isolated from crosses of the standard tester strains for these two species and from crosses between these standard testers and a field isolate (KSU X-10626) that was cross-fertile with tester strains of both species. Progeny in all of the crosses segregated for amplified fragment length polymorphisms (AFLPs). Segregation of AFLP loci deviated from 1:1 for two thirds of the loci amongst the progeny of the cross between the ‘C’ and ‘D’ mating population tester strains, but <20% of the polymorphic loci in the cross of either tester with KSU X-10626 showed such distortion. It was concluded that G. intermedia and G. fujikuroi are sufficiently interfertile to belong to the same biological species, but that changing the nomenclature to reflect this interfertility requires more evidence for the natural occurrence of a continuum in fertility than is presently available. 相似文献
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Jesty SA Sweeney RW Dolente BA Reef VB 《Journal of the American Veterinary Medical Association》2005,226(9):1555-8, 1502
Idiopathic pericarditis is an uncommon diagnosis in cattle with cardiac tamponade. Two cows were examined for clinical signs of right-sided congestive heart failure, including tachycardia, venous distention, and peripheral edema. Muffled heart sounds were detected in one of the cows. Echocardiography in both cows revealed voluminous anechoic pericardial effusion and compression of the right atrium and right ventricle. Cytologic analysis of the pericardial fluid revealed hemorrhagic inflammation but no evidence of a septic or neoplastic condition such as traumatic reticulopericarditis or lymphoma, respectively. Pericardial drainage and lavage accompanied by treatment with anti-inflammatory drugs were curative in both cows. It is important to differentiate cows with idiopathic pericarditis from cows with more common septic pericarditis because the prognosis for the former disease appears to be good with appropriate treatment. 相似文献
7.
Chae C Cheon DS Kwon D Kim O Kim B Suh J Rogers DG Everett KD Andersen AA 《Veterinary pathology》1999,36(2):133-137
Gnotobiotic piglets were inoculated intralaryngeally with swine Chlamydia trachomatis strain R33 or orally with swine C. trachmatis strain R27. Archived formalin-fixed, paraffin-embedded tissues from piglets euthanatized 4-7 days postinoculation were examined by in situ hybridization for C. trachomatis nucleic acid using a nonradioactive digoxigenin-labeled DNA probes that targeted specific ribosomal RNA or omp1 mRNA molecules of the swine C. trachomatis strains. Positive hybridization signals were detected in bronchial epithelial cells, bronchiolar epithelial cells, pneumocytes, alveolar and interstitial macrophages, and jejunal and ileal enterocytes. Chlamydia-infected cells had a strong signal that was confined to the intracytoplasmic inclusions. Positive hybridization signals were not detected in tissue sections from an uninfected control piglet or in C. psittaci-infected sheep placenta. The morphology of host cells was preserved despite the relatively high temperature required in parts of the incubation procedure. The data indicate that in situ hybridization can be used to detect swine C. trachomatis in formalin-fixed, paraffin-embedded tissue specimens. 相似文献
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The development and survival of the eggs of Nematodirus filicollis placed on grass plots over a period of a year were studied. Development took place at every season although it was more rapid in the warmer months. Yields of larvae were highest from eggs placed outside during February, March and April. Larvae persisted for two to two and a half years after eggs were placed on the pastures. The extraordinary persistence of the eggs and larvae of N filicollis makes control of the parasite difficult. 相似文献
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