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1.
Argentine hake (Merluccius hubbsi) was stored chilled for 8 days. The evolution of fluorescence of the aqueous and organic extracts of muscle during storage at 4°C was studied and correlated with common damage indices; pH, total volatile basic nitrogen, free fatty acids, and the fluorescence intensity of the aqueous phase showed a good correlation with storage time. The excitation-emission matrices of the aqueous extracts were also obtained. A fluorescence landscape that could be attributed to tryptophan decreased with storage time, meanwhile a peak (around 340 and 400 nm for excitation and emission wavelengths, respectively) is developed during chilled storage.  相似文献   
2.
The effects of aflatoxin B1 on the development of the immune response to oil-adjuvanted Bordetella bronchiseptica vaccine and on acquired resistance to bacterial challenge were studied in rabbits. The doses of aflatoxin used were insufficient to produce clinical intoxication. Rabbits were randomly assigned to three groups, each having six animals: control (T), vaccinated (V), and vaccinated plus aflatoxin (VA) at 0.05 mg/kg daily per os. Groups V and VA were vaccinated twice, and the three groups were subsequently challenged with virulent B. bronchiseptica. The average weight gain at weekly intervals was significantly reduced in group VA, and no statistically significant differences were found in the titers of agglutinating antibodies between groups V and VA. There were significant differences between groups V and VA in the extent and severity of the pneumonic process, group VA being most affected. Results indicated that agglutinating antibody titers were not related to the level of protection in the latter group. Other mechanisms, such as alveolar macrophage activity and cell-mediated immunity, were implicated in the impairment of the acquired resistance in rabbits subclinically intoxicated with aflatoxin.  相似文献   
3.
The objective was to study the essential oil composition of coriander fruits in plants growing in environments differing in soil conditions and weediness level. Factorial field experiments were conducted in two locations from the Rolling Pampas, Argentina, and two coriander landraces (European and Argentinean) were tested under two levels of nitrogen fertilization and weediness. Data were evaluated with uni- and multivariate techniques. The variation in the oil composition was related to the relative proportion of the constituents and not to the presence/absence of a particular component. Weather conditions in 1997 favored linalool and camphor in both landraces. Location, fertilization, and weediness also affected the chemical profile. The European landrace showed a more stable concentration of the major components than the Argentinean landrace. These results, which show the relationships between some environmental conditions and the essential oil composition, are useful in the development of innovative strategies aimed to improve oil composition and to manage crop pests.  相似文献   
4.
Dirofilaria immitis, the etiological agent for heartworm disease, is a zoonotic, vector-borne parasite. The dog is the most common natural host. Heartworm disease is present in all US states, as well as in South and Central America, Asia, Europe, Africa and Australia [. Prevalence of feline heartworm disease - a global review. In: Proceedings of the Heartworm Symposium'95, Auburn, Alabama, USA, 31 March-2 April, 1995. American Heartworm Society, Batavia, USA, pp. 79-86]. According to Menda [Menda, J.A., 1989. Transplacental migration of Dirofilaria immitus microfilariae. Companion Anim. Pract. 19 (6-7), 18-20], 18% of the canine population in the city of Santo Domingo tested positive for heartworm using the Filar Assay Kit. In the year 2000, clinical veterinarians from the Samana Peninsula in the Dominican Republic stated that the incidence of heartworm was minimal (Goodman, personal communication). In this small epidemiological study performed during the summer of 2001, 104 dogs from the Samana Peninsula were tested for heartworm antigen with the WITNESS HW Test and a wet mount evaluation for microfilaria under light microscopy. It was found that 18.2% of the canine population tested positive according to either one or both of the diagnostic methods. It would be advisable to apply prevention measures to control Dirofilaria immitis infection in the canine population of the Samana Peninsula in the Dominican Republic.  相似文献   
5.
The Mycoplasma hyopneumoniae genome contains at least 22 regions with a variable number of tandem nucleotide repeats (VNTRs) within coding DNA sequences (CDSs). In this work, the VNTR-containing CDSs were analysed in order to evaluate their degree of variation, possible correlations with antigenic properties, and their potential to be used as a basis for a strain typing PCR assay. We have analysed the VNTRs in five M. hyopneumoniae strains (J, 7448, 7422, PMS, and 232), based on published genomic sequences and on amplified and sequenced DNA segments. These VNTRs are distributed among 12 genes, most of which encode putative surface proteins, including known adhesins. The number of repeat units in any of the VNTRs is highly variable among the analysed strains, but they are, without exception, translationally in frame, and, therefore, code for a variable number of aminoacid repeats (VNTARs). These VNTARs determine putative structural, physicochemical and antigenic variations in the corresponding proteins, with potential implications for aspects associated to M. hyopneumoniae pathogenicity, such as cell adhesion and interactions with the host immune system. Considering that the characterized VNTARs are relatively stable, at least in vitro, and their sizes are strain-specific, we have developed a VNTR-based PCR assay for M. hyopneumoniae strain identification, useful for enzootic pneumonia (EP) diagnosis, strain typing, and distinction of circulating field isolates from vaccine strains in animals vaccinated against EP.  相似文献   
6.
Echinostomiasis is a food-borne, intestinal, zoonotic, snail-mediated helminthiasis caused by digenean trematodes of the family Echinostomatidae with seven species of the genus Echinostoma infecting humans or domestic and wildlife animals. Echinostoma paraensei is a peristomic 37-collar-spined echinostome belonging to the “revolutum group”.  相似文献   
7.
The optimum culture conditions of the local strain Chaetoceros calcitrans were determined to improve biomass and reduce cost of production. Under outdoor culture conditions, higher cell density was attained when the cultures were enriched with Tungkang Marine Research Laboratory (TMRL) medium composed of cheap technical grade reagents and cultured at 25 g L?1 salinity. The cultures were lighted with two 40 W cool-white GE fluorescent tubes (24–35 μmol photon m?2 s?1). Using semi-continuous culture system under established optimum culture conditions, C. calcitrans can be re-cultured thrice and concentrated at each culture cycle using electrolytic flocculation method to produce 4.6 kg m?3 of diatom paste. The viability of concentrated C. calcitrans after 3 months of storage was comparable to live diatom cells. Simple preservation technique by low-temperature storage is convenient for storing algal concentrates for use as starter cultures and for feeding invertebrates. The paste costs USD 8.24 kg?1 inclusive of the assets and flocculation materials for culturing and harvesting the diatom, respectively. This study established the suitable conditions for mass culture of C. calcitrans and produced concentrated diatoms in paste form that is readily available for aquaculture hatcheries at a lower cost.  相似文献   
8.
A chemical study of acyl-homoserine lactones (acyl-HSLs) produced by Enterobacter sakazakii resulted in the identification of three molecules: (S)-N-heptanoyl-HSL, (S)-N-dodecanoyl-HSL and (S)-N-tetradecanoyl-HSL. Mixed cultures of E. sakazakii and Bacillus cereus depleted E. sakazakii acyl-HSLs, suggesting acyl-HSL degradation by B. cereus hydrolases (hydrolysis of the lactone or amide moiety). The expression of B. cereus acyl-HSL lactonase and acyl-homoserine acylase was confirmed by monitoring the biotransformation of (S)-N-dodecanoyl-HSL into (S)-N-dodecanoyl-homoserine, dodecanoic acid and homoserine in the presence of B. cereus whole cells, using electrospray-mass spectrometry (ESI-MS).  相似文献   
9.
Endothelial dysfunction contributes to the development of ungulate's laminitis. Although extensively studied in equines, the endothelial function is not fully examined in bovine digital veins (BDVs). BDVs were studied under isometric conditions to describe the acetylcholine (ACh) endothelium‐dependent relaxation. Concentration–response curves were constructed to phenylephrine, ACh, and sodium nitroprusside (SNP). Relaxation responses were evaluated using either phenylephrine or depolarizing high‐potassium Krebs solution (DKS) as precontraction agents. Endothelium denudation and incubation with L‐NAME (300 μM), indomethacin (10 μM) or both were used to explore endothelial‐mediated mechanisms. Endothelium denudation did not modify phenylephrine and SNP responses, however, significantly (p < 0.05) converted a relaxation (63.2 ± 5%) response to ACh into a contraction (30.3±9%). The ACh‐evoked relaxation was significantly (p < 0.05) reduced in the presence of indomethacin (37.5 ± 6%) and L‐NAME (6.40 ± 2%). The presence of both inhibitors abolished the ACh‐evoked relaxation. Although DKS caused a higher precontraction than phenylephrine, ACh‐evoked relaxation (22.4 ± 3.4%) was still observed and was reduced by the combination of inhibitors (7.0 ± 1.0%). The ACh endothelium‐dependent relaxation in BDVs is essentially mediated by nitric oxide and endothelium‐derived prostanoids. The BDV endothelium function is a dynamic component in the control of the bovine digital blood flow, particularly under endothelial dysfunction conditions when venoconstriction might lead to postcapillary resistance increase.  相似文献   
10.
Sensory quality is an important property of virgin olive oil and is affected by different volatile and phenolic compounds. Their levels may be influenced by many factors, and one of the most important is the cultivar. Volatiles and phenols were correlated to sensory notes in virgin olive oils from 18 local cultivars in northern Italy assessed for 4 years in the same orchard.  相似文献   
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