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排序方式: 共有130条查询结果,搜索用时 15 毫秒
51.
Parra A García N García A Lacombe A Moreno F Freire F Moran J Hermoso de Mendoza J 《Veterinary microbiology》2008,129(3-4):315-324
Biofilm formation where bacterial cells adhere to a surface and surround themselves in a polysaccharide matrix is thought to be an important factor in disease initiation and persistence for many bacterial species. We have examined biofilm formation by Mycoplasma mycoides subsp. mycoides small colony using a simple model without an air/liquid interface and have found that adherent Mmm SC was more resistant to many stresses, including heat, osmotic shock and oxidative stress. Biofilms of Mmm SC also exhibited remarkable persistence and were able to survive for up to 20 weeks in stationary phase. Significant variation was seen between Mmm SC strains in their ability to form a biofilm and the morphology of the biofilm produced with some strains unable to produce microcolonies. Proteomic analysis found that a number of proteins linked to adherence were over-expressed in biofilms compared with planktonic cells. 相似文献
52.
Grajal A Strahl SD Parra R Gloria Dominguez M Neher A 《Science (New York, N.Y.)》1989,245(4923):1236-1238
The only known case of an avian digestive system with active foregut fermentation is reported for the hoatzin (Opisthocomus hoazin), one of the world's few obligate folivorous (leaf-eating) birds. Hoatzins are one of the smallest endotherms with this form of digestion. Foregut fermentation in a flying bird may be explained by increased digestive efficiency by selection of highly fermentable and extremely patchy resources, coupled with microbial nutritional products and secondary compound detoxification. This unexpected digestive system gives a new perspective to the understanding of size limitations of vertebrate herbivores and to the evolution of foregut fermentation. 相似文献
53.
54.
Laura González Raúl Bermejo María Asunción Parra David Elustondo Jordi Garrigó Jesús Miguel Santamaría 《Water, air, and soil pollution》2010,206(1-4):23-34
Ground-level dynamics of O3, NO x and benzene, toluene, ethylbenzene and xylenes were characterised at rural sites in the medium Ebro River Basin (Northern Spain) from April to September (2003–2007) and by means of automated and passive monitoring. The study registered high O3 levels within the area, which were influenced by traffic emissions, and a monthly evolution of these levels consistent with the occurrence of a broad summer maximum, typical of polluted areas. The mean ozone concentration registered in the studied area by means of passive sampling was 87?±?12 μg m?3. The 2008/50/EC objective value for the protection of vegetation was widely exceeded during this study (AOT40?=?57,147?±?14,114 μg m?3 h), suggesting that current ambient levels may pose a risk for crops and vegetation in this important agroindustrial region. 相似文献
55.
Farnós O Rodríguez M Chiong M Parra F Boué O Lorenzo N Colás M Lleonart R 《Veterinary microbiology》2006,114(3-4):187-195
Rabbit hemorrhagic disease (RHD) is a contagious and highly lethal viral disease of rabbits that spreads rapidly and infects animals by nasal, conjunctival and oral routes. Therefore, this experiment was undertaken to study the immune response generated after intranasal (i.n.) vaccination with the recombinant VP60 capsid protein from rabbit hemorrhagic disease virus (RHDV) expressed at high levels in Pichia pastoris. Groups of BALB/c mice were immunized with three doses of purified VP60 protein (Group 1), VP60 formulated within the cell debris fraction of the transformed yeast (Group 2) and placebo (Group 3) by intranasal route. Mice were also intramuscularly injected with purified VP60 protein (Group 4). A rapid antibody response specific against rabbit hemorrhagic disease virus was observed in all the experimental groups, except in Group 3, as detected by ELISA. The highest titers were found 60 days after the first immunization. Mice from Group 1 showed the highest IgG response (p<0.05) and the most balanced profile of IgG1, IgG2a and IgG2b subclasses. IgA titers specific to the virus were found only in animals from this group, which also developed the highest specific lymphocyte proliferative response. Interferon-gamma (IFN-gamma) and interleukin-12 (IL-12) gene expression was also detected after an ex vivo-specific stimulation of mice from Groups 1 and 4. These data demonstrated the capacity of VP60 protein expressed in P. pastoris to elicit a potent humoral and cell-mediated immune response following an intranasal immunization scheme. 相似文献
56.
Inorganic and organic clays as carriers for controlled release of the herbicide hexazinone 总被引:7,自引:0,他引:7
Celis R Hermosín MC Carrizosa MJ Cornejo J 《Journal of agricultural and food chemistry》2002,50(8):2324-2330
The risk of ground water contamination resulting from rapid leaching of highly soluble pesticides can be minimized through the application of the pesticide adsorbed on a matrix or carrier, which limits the amount of pesticide immediately available for undesirable losses. The use of natural materials for this purpose is of special interest in terms of economy and sustainability. In this work the adsorption of the herbicide hexazinone by two montmorillonites saturated with various inorganic and organic cations was determined and the ability of the two clays displaying the highest adsorption capacities [Fe(3+)-saturated Wyoming montmorillonite, (Fe-SW) and hexadecyltrimethylammonium-saturated Arizona montmorillonite (HDTMA-SA)] to act as carriers for slow release of hexazinone and to reduce herbicide leaching losses was evaluated. Hexazinone formulations based on Fe-SW and HDTMA-SA displayed slow release properties in water and soil/water suspensions, reduced herbicide leaching in soil columns, and maintained herbicidal activity, as compared with the currently available commercial hexazinone formulation (wettable powder). Loosely bound hexazinone-HDTMASA formulations, which led to the slowest breakthrough of hexazinone in soil columns along with the greatest amounts of herbicide released from the clay particles, displayed the most interesting characteristics for their use as slow release formulations and to prevent ground water contamination. 相似文献
57.
Lemos SG Nogueira AR Torre-Neto A Parra A Artigas J Alonso J 《Journal of agricultural and food chemistry》2004,52(19):5810-5815
A potentiometric sensor system based on potassium ion-selective electrodes was developed for agricultural purposes. Sensors were built using PVC ion-selective membranes over an inner solid contact prepared with graphite-epoxy composites. A copper plate was used as a reference electrode. A two-stage electronic circuit composed of current and voltage amplifiers was designed to interface the sensors to a distributed data acquisition system. Three ion-selective sensors and three off-the-shelf temperature sensors and their associated circuits were mounted in a PVC tube to set up a soil probe. The electronic controls were placed in an airtight box fixed at the upper part of the probe. The system was evaluated in the field, where the sensors presented sensibility within the range of 69-71 mV dec(-)(1). Extracts of soil samples were analyzed by a current flame photometry approach, and the results, compared with the probe measurements, showed a linear relationship (r (2) = 0.992 and 0.995, respectively, to 5 and 20 cm depths), which implies viability and instrumentation reliability for agricultural applications. 相似文献
58.
Very little is known about the ecology of snubfin Orcaella heinsohni and Indo-Pacific humpback dolphins Sousa chinensis in Australian waters. We used photo-identification data collected between 1999 and 2002 in Cleveland Bay, northeast Queensland, to estimate abundance, site fidelity and residence patterns of these species in order to make recommendations for their effective conservation and management. Our abundance estimates indicate that less than a hundred individuals of each species inhabit this coastal area. Even with relatively unbiased and precise abundance estimates population trends will be extremely difficult to detect in less than three years unless changes in population size are very high (>20% p.a.). Though both species are not permanent residents in Cleveland Bay, they both used the area regularly from year to year following a model of emigration and reimmigration. Individuals of both species spend periods of days to a month or more in coastal waters of Cleveland Bay before leaving, and periods of over a month outside the study area before entering the bay again. Because of their small population sizes and movement patterns, snubfin and humpback dolphins are particularly vulnerable to local extinction. Our results illustrate that: (1) detection of population trends should not be a necessary criterion for enacting conservation measures of both species in this region, and (2) efforts to maintain viable populations of both species in Cleveland Bay must include management strategies that integrate anthropogenic activities in surrounding areas. 相似文献
59.
García-Sánchez A Cerrato R Larrasa J Ambrose NC Parra A Alonso JM Hermoso-de-Mendoza M Rey JM Hermoso-de-Mendoza J 《Veterinary microbiology》2004,99(1):67-74
A random amplified polymorphic DNA (RAPD) procedure was used to identify a specific 0.6 kb DNA fragment unique to Dermatophilus congolensis. This 0.6 kb fragment was evaluated as a specific DNA probe and used to design oligonucleotide primers for polymerase chain reaction (PCR) amplification. The nucleotide sequences adjacent to this DNA fragment were determined by inverse PCR allowing the identification of a 4.1 kb sequence. Analysis of this revealed a complete open reading frame (ORF) with a high similarity to an alkaline ceramidase from Pseudomonas aeruginosa. The molecular weight of the enzyme derived from the predicted amino acid sequence is 74,662 Da, its pI is 9.81. The predicted N-terminal sequence of the enzyme contains a signal sequence indicating that the enzyme is exported by the bacterium. Since ceramides have important protective and cell regulatory roles in the epidermis we suggest that this ceramidase may have a role in the pathogenesis of dermatophilosis. It is the first completely sequenced gene described for D. congolensis. 相似文献
60.
Ana Matus de la Parra Antonio Rosas Juan Pablo Lazo Maria Teresa Viana 《Fish physiology and biochemistry》2007,33(3):223-231
The digestive enzyme activities of Pacific bluefin tuna Thunnus orientalis were evaluated for specific activity and characterized for pH and temperature optima in crude extracts of stomach, caecal
mass, and proximal, middle and distal intestine. A higher level of alkaline proteolytic activity was detected in the caecal
mass than in the proximal intestine. Total alkaline proteases, trypsin, chymotrypsin and leucine aminopeptidase (LAP) were
tested. The temperature and pH analyses showed that proteolytic activity as well as lipase were maximal in the alkaline range,
with a maximum at pH 9.0 and at temperatures between 35 and 60°C, except for the pepsin, which showed maximum activity at
the same temperatures but in the acid range (pH 3.0). The α-amylase activity showed a broader range in activity, both for
pH and temperature, with higher activity over the alkaline pH values and higher temperature. The lipase activity seems to
be nondependent on bile salts under our assay conditions, resulting in a significant activity reduction in the presence of
bile salts. This knowledge will allow the development of a gastrointestinal model (everted intestine) where food or feed will
be hydrolysed with the fish’s own enzymes, a project that is being undertaken in our laboratory as a contribution to the development
of novel diets for tuna fish. 相似文献