Experiments carried out in a turkey processing plant showed that there was a fivefold increase in the number of psychrophilic bacteria present after holding eviscerated carcasses in static slush ice tanks for 24 hr. The predominant bacteria in the 24 hr chill tanks were strains of Flavobacterium, Cytophaga and Pseudomonas.
The carcasses were wrapped in heat‐shrunk‐oxygen‐impermeable film and after freezing packed in individual boxes and held at ‐20° C. The storage life at 1°, 10° and 20° C. was determined together with the time taken for the frozen carcasses to equilibrate to these temperatures. It was found that at 1° C. the carcasses kept for about 3 weeks, but at 10° C. they spoiled within 7 days and at 20° G. within 3 days.
An analysis of the spoilage flora showed that although Pseudomonas strains predominated on the turkeys stored at 1° C. fewer were isolated from turkeys stored at 10° C. and 20° C. At these two temperatures an organism identified as Enterobacter liquefaciens predominated together with atypical lactobacilli resembling unidentified strains previously described by Thornley and Sharpe (1959). 相似文献
Enteropathogenic Escherichia coli (EPEC) previously were identified in poult enteritis-mortality syndrome (PEMS)-affected turkeys and associated as a cause of this disease. In the present study, the prevalence of EPEC in PEMS-affected turkeys was examined retrospectively with archived tissues and intestinal contents collected from 12 PEMS-affected turkey flocks in 1998. Formalin-fixed intestinal tissues were examined by light and electron microscopy for attaching and effacing (AE) lesions characteristic of EPEC, and frozen (-75 C) intestinal contents were examined for presence of EPEC. Escherichia coli isolates were characterized on the basis of epithelial cell attachment, fluorescent actin staining (FAS) test, and presence of E. coli attaching/effacing (EAE), shigalike toxin (SLT) type I, SLT II, and bundle-forming pilus (BFP) genes by polymerase chain reaction procedures. EPEC isolates were examined for pathogenicity and ability to induce AE lesions in experimentally inoculated young turkeys. AE lesions were identified by light microscopy in Giemsa-stained intestines from 7 of 12 PEMS-affected turkey flocks. Lesions consisted of bacterial microcolonies attached to epithelial surfaces with epithelial degeneration at sites of attachment and inflammatory infiltration of the lamina propria. Electron microscopy confirmed the identity of AE lesions in six of seven flocks determined to have AE lesions by light microscopy. EPEC were identified in 4 of 12 flocks on the basis of the presence of EAE genes a nd absence of SLT I and SLT II genes; all isolates lacked BFP genes. EPEC isolates produced AE lesions and variable mortality in turkeys coinfected with turkey coronavirus. In total, EPEC were associated with 10 of 12 (83%) naturally occurring PEMS cases on the basis of identification of AE lesions and/or EPEC isolates. These findings provide additional evidence suggesting a possible role for EPEC in the pathogenesis of PEMS. 相似文献
Matrix metalloproteinases (MMPs), which degrade tissues in health and disease are under the control of the tissue inhibitors of MMPs, the TIMPs. TIMP-2 is particularly important for control of MMP-2 and both have been implicated in many pathological processes from arthritis to tumour invasion. This study characterized and detected TIMP-2 from canine cells; including synovial fibroblasts and three tumour-derived canine cell lines, K1, K6 and DH82. Gelatin zymography demonstrated that pro-MMP-2 is produced by synovial fibroblasts and the three cells lines. Reverse zymograms showed that all the cell sources tested secrete both TIMP-1 and TIMP-2. The 22 kDa band was purified and n-terminal amino acid sequencing showed it to be highly homologous to equine and human TIMP-2. Analysis of purified canine MMP-2 and MMP-9 showed that TIMP-2 is associated, and co-purifies with MMP-2. Polymerase chain reaction, using consensus primers, was used to detect TIMP-2 mRNA from the cell sources and proved positive in all cases. This work highlights the importance of TIMP-2 as the main inhibitor for MMP-2 and, therefore, opens the possibilities of targeting TIMP-2 for therapeutic intervention against connective amino acid tissue degradation in a range of diseases. 相似文献
One-year-old loblolly pine (Pinus taeda L.) seedlings from four seed sources (Arkansas, Georgia, Texas and Virginia) grown in 1-m-deep sand-filled pits in two water regimes (well-watered and drought) were studied, to gain insight into the process of seedling establishment. Whole-plant transpiration was measured biweekly from July to December. Whole-plant harvests were conducted at 6-week intervals from April to December. Whole-plant transpiration and transpiration per unit leaf and root area were affected by treatment, seedlot and phenology. Seedlings of the Arkansas seedlot maintained significantly higher transpiration rates per unit leaf and root area during drought than seedlings of the Virginia, Georgia or Texas seedlots, but did not accumulate greater biomass. The high transpiration rates of the Arkansas seedlings were attributed to their deep root systems. Allometric relationships indicated that, relative to the whole plant, biomass allocation to needles of drought-treated seedlings was enhanced during the summer (allometric ratio 1.09), whereas allocation to roots was enhanced in the spring and fall (allometric ratios of 1.13 and 1.09, respectively). Relative to the whole plant, biomass allocation to needles of well-watered seedlings was enhanced throughout the experiment (allometric ratio of 1.16 declining to 1.05), whereas the allometric ratio of root to total biomass was 0.89 or less throughout. Allometric relationships also indicated variation in biomass partitioning to roots in three soil layers (0-30, 30-60 and 60-100 cm), which differed among harvests in each soil layer. Root growth in both well-watered and drought-treated seedlings was concentrated in the top soil layer in the spring, shifted to the middle and bottom soil layers in the summer, and then increased in the top soil layer in the fall. Compared with well-watered seedlings, drought-treated seedlings had higher rates of root growth in the bottom soil layer in the fall, a characteristic that would confer tolerance to future periods of limited soil water availability. 相似文献
Seiridium cardinale, the cause of cypress canker disease, was found on Juniperus foetidissima, J. excelsa, J. oxycedrus and J. phoenicea, in a number of natural juniper woodlands in Greece. The presence of infections was sporadic in most cases, with a limited number of plants affected by the pathogen. At one locality in the Prespes Lakes region of northern Greece, however, the incidence of infection was very high, especially on J. foetidissima and J. excelsa. The identity of S. cardinale was confirmed using morphological characters and comparisons of DNA sequences for the β‐tubulin gene region. The pathogenicity of S. cardinale isolates from Juniperus and Cupressus was verified in cross‐inoculation trials on both potted and field grown plants. 相似文献
The prevalence of endocrine‐disrupting chemicals (EDCs) in the aquatic environment has been associated with the wide detection of alterations in the development and physiology of vertebrates. Zebrafish, as a model species, has been extensively used in toxicological research. In this review, we focus on recent published evidence of the harmful effects of EDCs on reproductive function in zebrafish, including skewed sex ratio, immature gonads, diminished sexual behaviour, decreased sperm count, reduced spawning and fertilization. These impairments mostly result from disruption to sex‐steroid hormones induced by endocrine disruptors. We also discuss other effects of exposure to EDCs. In EDC exposure research, despite incomplete assessments of altered gonad histopathology and sexual behaviour, these present potential effective biomarkers or pathways for evaluating the reproductive function in zebrafish on EDC exposure. To date, the pernicious effects of some EDCs on the reproductive performance in laboratory zebrafish are well understood; however, similar alterations remain for further determination in wild‐type fish and more kinds of EDCs. More studies should be performed under established scientific regulatory criteria to investigate the impact of EDCs on reproduction in zebrafish. Moreover, further research is required to explain the definite mechanism of sexual differentiation, which helps in understanding the shift of sexual phenotype with EDC exposure. 相似文献
Buckwheat (Fagopyrum esculentum Moench) protein (BWP) exhibits hypocholesterolemic activity in several animal models by increasing fecal excretion of neutral and acidic sterols. In the current study, the ability of BWP to disrupt micelle cholesterol solubility by sequestration of cholesterol was investigated. When BWP (0.2%) was incubated with cholesterol and micelle lipid components prior to micelle formation, cholesterol solubility was reduced 40%. In contrast, cholesterol solubility was not decreased when BWP (0.2%) was incubated after micelle formation and incorporation of soluble cholesterol. Buckwheat flour, from which BWP was derived, had no significant effect on cholesterol solubility. Cholesterol uptake in Caco-2 cells from micelles made in the presence of BWP (0.2%) was reduced by 47, 36, 35, and 33% when compared with buckwheat flour, bovine serum albumin, casein, and gelatin, respectively. Reduction in cholesterol uptake in Caco-2 cells was dose-dependent, with maximum reductions at 0.1-0.4% BWP. In cholesterol-binding experiments, 83% of the cholesterol was associated with an insoluble BWP fraction, indicating strong cholesterol-binding capacity that disrupts solubility and uptake by Caco-2 cells. 相似文献