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131.
The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H2) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H2 indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.  相似文献   
132.
Immunoglobulin M (IgM) is a major component of the teleost humoral immune system. Despite the significance of IgM levels as an immune parameter, there are relatively few studies on changes induced in its total levels in serum. This study examines the effects of several immunomodulators (vitamin A, chitin, yeast cells or levamisole, which act as immunostimulants, and crowding, hypoxia or anaesthetics, which act as stressors) upon the total serum IgM levels of non-immunized gilthead seabream (Sparus aurata L.). Total serum IgM levels of fish fed with the assayed immunostimulant-supplemented diets were statistically higher than those in fish fed a non-supplemented diet, especially in the case of levamisole. On the other hand, serum IgM levels of fish subjected to different stressors were not affected by crowding, hypoxia or certain anaesthetics. However, benzocaine and a narcotic dose of 2-phenoxyethanol provoked a great reduction, while quinaldine sulphate increased IgM levels to a significant degree. These results show how the seric IgM levels can be differently affected by some immunomodulators and the important role they may play in the regulation of total circulating IgM levels in seabream. The possibility of using total serum IgM for assessing immunostimulation, disease diagnosis and stress symptoms during fish farming is discussed.  相似文献   
133.
1. The rates of gastrointestinal (GI) emptying of 8- and 15-d-old chickens treated with 17-hydroxycorticosterone was measured using 14C-polyethylene glycol-4000. 2. The rate of progression of intraluminal contents along the GI tract was decreased by 17-hydroxycorticosterone in both 8- and 15-d-old chickens. Glucocorticoid treatment only delayed the rate of progression of intraluminal contents along the large intestine of the older birds. 3. Delayed transit of intraluminal contents could be explained by a precocious maturation of chick GI tract, induced by glucocorticoids. Loss of responsiveness to glucocorticoids occurs during the second week after hatching, except in the large intestine.  相似文献   
134.
A cross-sectional study was carried out in the Basque Country of Spain to determine the seroprevalence of 10 Leptospira serovars in a population of dairy cattle with poor fertility, and a case-control study was carried out in another northern area to investigate the role of Leptospira interrogans serovar Bratislava in abortions. L. Bratislava was the most prevalent serovar in the cross-sectional study, with 25.4 per cent of the cows testing positive in the microagglutination test when a cut-off of 1:10 or higher was applied, followed by Leptospira Hardjo (8.2 per cent), Leptospira Pomona (7.7 per cent), Leptospira Autumnalis (0.7 per cent) and Leptospira Copenhageni (0.1 per cent). In the case-control study the seroprevalence of L. Bratislava was significantly higher among the cows which had aborted when a titre of 1:300 or more was used as a cut-off (9.7 per cent v 3.4 per cent, P=0.008); 69 per cent of the L. Bratislava-infected cows that had aborted apparently aborted as a result of the infection.  相似文献   
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Three-hundred and forty-five herds (17 swine, 122 dairy sheep, 124 beef and 82 dairy cattle) were investigated for prevalence of Shiga toxin-producing Escherichia coli (STEC). Rectal faecal samples were selectively enriched and then examined by immunodetection techniques (Immunomagnetic Separation with anti-E. coli O157 Dynabeads, ImmunoMagnetic cell Separation (IMS) and automated enzyme-linked fluorescent immunoassay using VIDAS) and polymerase chain reaction (PCR) (rfbE and fliC genes) to assess the prevalence of E. coli O157:H7. Prevalence of non-O157 STEC was estimated by PCR screening for stx genes of 10 lactose-positive colonies grown on MacConkey agar after enrichment. PCR was used on all STEC isolates to detect stx(1), stx(2), eaeA and E-hlyA genes. Both immunodetection methods showed a moderate-good level of agreement (kappa = 0.649) but IMS showed 87.5% complementary sensitivity. Prevalence of positive herds for E. coli O157:H7 was estimated at 8.7% for sheep and 3.8% for cattle, whereas all the porcine herds tested negative. Non-O157 STEC were also absent from swine, but were isolated more frequently from ovine (50.8%) than bovine herds (35.9%). Within-herd prevalences of excretion of E. coli O157:H7 established by individual testing of 279 sheep (six herds) and 30 beef cattle (one herd) were 7.3% and 6.7% respectively. PCR analysis of 49 E. coli O157:H7 and 209 non-O157 isolates showed a different distribution of virulence genes. All E. coli O157:H7 were stx(2) gene-positive, eaeA was detected in 95.9%, and the toxigenic profile stx(2)/eaeA/E-hlyA was present in 75.5% of the isolates. Among the non-O157 STEC, prevalence of eaeA was significantly lower (5.3%) and E-hlyA was present in 50.2% of the isolates but only sporadically associated with eaeA. stx(2) was predominant in non-O157 isolates from cattle, whereas in sheep the combination stx(1)/stx(2) was more prevalent. This study demonstrated the wide distribution of STEC in ruminant herds, which represent an important reservoir for strains that pose a potential risk for human infections.  相似文献   
137.
Probiotic bacteria are known to exert a wide range of beneficial effects on their animal hosts. Control of intestinal homeostasis, inflammation suppression and a reduction in the incidence of cancer all rely on the antiproliferative potential of probiotics. In this paper, we assess the antiproliferative activity of probiotics in two teleost fish cell lines SAF-1, a fibroblast cell line and EPC, an epithelioma from carp. Cells were grown in the presence of cytoplasmic extracts obtained from two bacterial strains, Lactobacillus delbrüeckii subsp. lactis (LDL) and 51M6. Proliferation and apoptosis were measured after 4, 24, 48 or 72h in culture by the crystal violet or by double staining flow cytometry assays, respectively. Generally, LDL had stronger effects on cell growth than 51M6. Moreover, SAF-1 cells were more susceptible to growth inhibition than EPC cells. Apoptosis took place following growth inhibition, especially when LDL extracts were used. The results are discussed in terms of the biological significance of probiotic bacteria that naturally occur on the fish mucosal surfaces with an emphasis on how dose and species specificity may be determinant factors.  相似文献   
138.
A heterologous in vitro system, using zona‐intact sheep oocytes, was used to evaluate the relationship between sperm factors of Iberian red deer thawed epididymal sperm and the percentage of cleaved oocytes. Epididymal spermatozoa were recovered from six males, diluted with freezing extender and cryopreserved. After thawing sperm motility (SM) and acrosome and membrane integrities were evaluated. Again, these parameters were assessed after incubation in freezing extender at 37°C for 2 h. After cryopreservation the values for SM and acrosome and membrane integrities were high (~80, 80 and 70% respectively). However, these values significantly decreased after incubation (~59, 62 and 47% respectively). Red deer thawed epididymal sperm fertilized zona‐intact sheep oocytes, although the percentage of cleaved oocytes was low (~22%). No relationship was found between sperm parameters assessed after thawing and the percentage of cleaved oocytes. Likewise, any sperm parameter evaluated after incubation was assessed in relation to the percentage of cleaved oocytes. However, acrosome and membrane integrities were near to significance (p = 0.06 and p = 0.09 respectively). Then, we conducted a reduced model with these two variables and both were related to the percentage of cleaved oocytes (p = 0.02 and p = 0.04 respectively). Thus, acrosome and membrane integrities were related to the percentage of cleaved oocytes negatively and positively respectively. It was concluded that the classical parameters assessed in deer thawed sperm samples can be good predictors of the ability to fertilize zona‐intact sheep oocytes.  相似文献   
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