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31.
Sarradell J Andrada M Ramírez AS Fernández A Gómez-Villamandos JC Jover A Lorenzo H Herráez P Rodríguez F 《Veterinary pathology》2003,40(4):395-404
Porcine enzootic pneumonia (PEN), caused by Mycoplasma hyopneumoniae (Mh), has been described in pigs in all geographic areas. The disease is characterized by high morbidity and low mortality rates in intensive swine production systems. A morphologic and immunohistochemical study was done to determine the cellular populations present in lung parenchyma of infected pigs, with special attention to the bronchus-associated lymphoid tissue (BALT). Polyclonal and monoclonal antibodies were used for the detection of antigens of Mh, T lymphocytes (CD3+, CD4+, and CD8+), IgG+ or IgA+ lymphocytes, and cells containing lysozyme, S-100 protein, major histocompatibility complex class II antigen or myeloid-histiocyte antigen. Findings in lung tissues associated with Mh infection were catarrhal bronchointerstitial pneumonia, with infiltration of inflammatory cells in the lamina propria of bronchi and bronchioles and alveolar septa. Hyperplasia of mononuclear cells in the BALT areas was the most significant histologic change. The BALT showed a high morphologic and cellular organization. Macrophages and B lymphocytes were the main cellular components of germinal centers. T lymphocytes were primarily located in perifollicular areas of the BALT, lamina propria and within the airway epithelium, and plasma cells containing IgG or IgA at the periphery of the BALT, in the lamina propria of bronchi and bronchioles, in alveolar septa, and around bronchial submucosal glands. The hyperplastic BALT in PEN cases consisted of macrophages, dendritic cells, T and B lymphocytes, and IgG+ and IgA+ plasma cells. CD4+ cells predominated over CD8+ cells. Local humoral immunity appears to play an important role in the infection. 相似文献
32.
Sánchez A Contreras A Jiménez J Luengo C Corrales JC Fernández C 《Veterinary microbiology》2003,94(1):71-77
With the aim of evaluating the effect of freezing goat milk samples on recovery of intramammary pathogens, 1200 milk samples from udder halves with subclinical intramammary infection were studied. Samples (20 ml) were frozen at -20 and at -80 degrees C. Thawing was carried out at room temperature at 7, 14, 21, 28, 58, 118, 178, 236 and 730 days after collection and bacteriological analyses were carried out to determine the number of colony forming units/ml (CFU/ml). Mixed model statistical analysis showed that bacterial group, temperature of storage, interaction of bacterial group and temperature of storage and the interaction of bacterial group, time and temperature of storage were statistically significant effects. For coagulase negative staphylococci (CNS), least squares means of log CFU/ml recovered at -20 and -80 degrees C were not different. Nevertheless, for Gram negative bacilli (GNB) a significant decrease was detected in samples frozen at -20 vs. -80 degrees C. At both temperatures and at different times of storage, significant increases were detected between log CFU/ml of CNS and values on day zero. At -20 degrees C, a significant decrease in GNB recovery was detected between freezing days zero and 730. This difference was not detected when goat milk samples infected by GNB were frozen at -80 degrees C. The results show that frozen milk samples can be useful in goat subclinical mastitis control programs. 相似文献
33.
34.
Salceda Fernández-Barredo Carolina Galiana Angel García Santiago Vega María Teresa Gómez María Teresa Pérez-Gracia 《Journal of veterinary diagnostic investigation》2006,18(5):462-465
The aim of this study was to determine at which production stages hepatitis E virus (HEV) is shed by the highest number of pigs and to estimate the relative risk associated with each stage. For this purpose, 146 fecal samples of pigs from 21 farms were studied. In addition, 1 sample from the manure ditch and another sample of drinking water, collected directly from the trough located in the pen, were taken from 16 farms. HEV RNA was detected in fecal samples from 34 pigs (23.29%). The production stages in which most pigs excreted HEV were weaners (41.7%) and pigs in the first month of feeding (60%). The results of the statistical analysis showed that the principal significant risk stage in HEV shedding was the first month of feeding (odds ratio [OR] 19.5, 95% CI 3.59-106.07, P = 0.001) followed by the weaners stage (OR 9.3, 95% CI .78-48.42, P = 0.008). In 8 out of 16 farms tested (50%) HEV RNA was detected in raw manure and in the water trough of only 1. Detection of HEV in manure ditches raises the concern of how to deal with manure of swine origin, because it is used as soil fertilizer. 相似文献
35.
Lourdes Fernández-Calvino Dionisio López-Abella Juan José López-Moya Alberto Fereres 《Phytoparasitica》2006,34(3):315-324
Two different aphid species,Myzus persicae (Sulzer) andHyalopterus pruni (Geoffroy) (Homoptera: Aphididae), were used to analyze their ability to transmit two different potyviruses,Potato virus Y (PVY) andPlum pox virus (PPV), to pepper (Capsicum annuum) andNicotiana benthamiana plants, respectively. In parallel experiments,M. persicae consistently transmitted both viruses with high efficiency, whereasH. pruni always failed to transmit either virus. This is in contrast to previous reports describingH. pruni as a vector of these potyviruses. Different aphid probing behavior among individual aphids of each species was obtained in
electrical penetration graph (EPG) experiments performed on pepper plants. This suggested thatH. pruni did not transmit these potyviruses due to behavioral differences during probing that impeded virus acquisition and/or inoculation.
It was found thatM. persicae usually makes its first probe within the first 2 min, whereasH. pruni individuals remained for more than 10 min on the plant before starting to probe. Furthermore,M. persicae individuals displayed their first intracellular puncture during the first minute of probing whereasH. pruni needed ∼ 15 min to penetrate the cell plasmalemma with their stylets. In addition, intracellular stylet punctures occurred
very frequently forM. persicae but was a rare event, never exceeding a single one, forH. pruni. The relevance of these findings for the epidemiological spread of potyviruses by different aphid species is discussed.
http://www.phytoparasitica.org posting May 14, 2006. 相似文献
36.
Cherry leaf spot (Blumeriella jaapii (Rehm) Arx.) is a very serious disease of wild cherry (Prunus avium L.), which produces premature leaf defoliation and vigor decrease. In two clonal seed orchards of P. avium naturally infected by B. jaapii, spatial heterogeneity and autocorrelation of neighbor damage caused by cherry leaf spot impeded proper analysis of the fungus incidence. The iterative spatial analysis (ISA), based on variography and kriging, was successfully used to eliminate the effect of this spatial heterogeneity in analysis of genetic variation in susceptibility to B. jaapii. Significant differences among P. avium clones were found, with moderate to high broad-sense heritability estimates. Genetic by environment interactions, although significant, were not quantitatively important. A strong relationship between leaf spot susceptibility and bud burst was found. However, other factors must be affecting the genetic variation in leaf spot susceptibility, as differences among clones remained highly significant when considering the bud burst as a covariate in the genetic model. 相似文献
37.
Pastur Guillermo Martínez Peri Pablo Luis Fernández María Cecilia Staffieri Gabriela Lencinas Mará Vanessa 《Journal of Forest Research》2002,7(3):165-174
Human commercial activities must be compatible with sustainable management to achieve species conservation in the natural
environment. After harvesting, diversity and abundance of understory species differ substantially from the pre-harvest situation.
Have knowledge of the changes that logging produces in all components of the system allows us to develop management alternatives
with reduced impacts. The objective of this work was to evaluate changes in density, biomass and diversity of understory species
along a forest shelterwood cut system management cycle in aNothofagus pumilio forest. Six forest management situations (postharvesting stands and different phases of forest development) were sampled
in a pureN. pumilio forest of Tierra del Fuego (Argentina) of middle-high site class (fromclass I toIII). Species number, density and biomass were modified substantially after a shelterwood cut. These were being greatest after
cutting and falling substantially when the forest canopy closes during theinitial growth phase, returning to values similar to this virgin forest when themature phase was reached. The impact of the forest management on understory species diversity is analyzed and discussed. The silvicultural
practices applied toN. pumilio forest in Tierra del Fuego permit the introduction of alien flora to the system, and produce great changes during the forest
management cycle.
To Celina Matteri, Itatí Ferraro, and Rosa Kofalt for their aid in taxonomical identification. To Juan Manuel Cellini, Ricardo
Vukasovic and Gregorio Martínez Pastur for their participation in the field work; and to the sawmillLos Castores, Universidad Nacional de la Patagonia Austral, Centro Austral de Investigaciones Científicas and Instituto Nacional de Tecnología
Agropecuaria for the institutional and financial support. 相似文献
38.
Moncaleán P Alonso P Centeno ML Cortizo M Rodríguez A Fernández B Ordás RJ 《Tree physiology》2005,25(1):1-9
Isolated cotyledons from mature Pinus pinea L. embryos were cultured in vitro in a factorial combination of 4.4, 10 and 44.4 microM N6-benzyladenine (BA) for 2, 4, 8, 16 and 35 days to optimize shoot regeneration. Incubation of explants in 44.4 microM BA for 4 days, in place of the standard incubation in 4.4 microM BA for 35 days, reduced the entire culture period to 4 weeks. Shortening the culture period had no significant effect on the caulogenic response or the number of buds formed per cotyledon. To establish the relationship between key moments in the caulogenic process induced by 4.4 microM BA and the endogenous concentrations of the active forms of BA and other isoprenoid-type cytokinins (CKs), we examined uptake, metabolism and amount of BA, as well as the amounts of zeatin, dihydrozeatin and their ribosides in P. pinea cotyledons after 1, 2, 6, 12 and 24 h, and 2, 4, 8, 16 and 35 days of exposure to 8-[14C]BA. Uptake and release of BA were associated with water movement between explants and the medium during the first 8 days of culture. The interconvertible forms of BA were the main metabolites formed in the tissues. Inactivation of BA as a result of conjugation or oxidation was insignificant. The endogenous concentration of BA + N6-benzyladenosine was 20-fold higher than the exogenously applied BA during the competence acquisition phase (Days 0-3). The concentration of isoprenoid-type CKs also increased 16-fold and then decreased during this time. Induction of shoot buds (Days 4-8) was characterized by a second peak of BA uptake by explants that triggered the synthesis of N6-benzyladenosine-5 -monophosphate and by the maintenance of isoprenoid-type CKs. Reestablishment of CK homeostasis marked the shift from the induction phase to the shoot development phase in this organogenic process (Days 8-12). 相似文献
39.
The aim was to determine the inoculation density above which Scots pine (Pinus sylvestris) is overcome by the blue‐stain fungus Ophiostoma ips that is associated with the bark beetle Ips sexdentatus. In north‐western Spain, stems of 16 Scots pines were inoculated at various densities (0, 400, 800 or 1600 inoculi/m2) along circumferential 100 or 150 cm wide inoculation belts. Each inoculum consisted of a 5 mm diameter cylinder of malt extract agar colonized by the fungus. Three months later, all trees were harvested and trunk resinosis and foliage colour were visually assessed. The percentage of healthy, desiccated, resin soaked, and blue‐stained sapwood, as well as growth productivity indices, were calculated from stem disks cut from within the inoculated zone of each tree. Sapwood‐specific hydraulic conductivity (Ks) of each tree was measured in the middle of the inoculated zone. All parameters of tree vigour changed dramatically to the worse when inoculation densities were above 400 inoculi/m2, and foliage changed from green to yellow‐green or yellow when an inoculation density of 800 instead of 400 was used. The percentage loss of sapwood‐specific conductivity (PLC) increased from 30 to 90% and the percentage of healthy, conductive sapwood dropped from 85 to 35% at 800 inoculi/m2. No effect of the width of the inoculation belt was observed, and there was no relationship between tree productivity indices and the level of resistance. A non‐linear negative relationship was found between PLC and the percentage of healthy sapwood. It is concluded that tree resistance was overcome and that trees were going to die when the inoculation density was ≥800 inoculi/m2. 相似文献
40.
Pilar Sancho Carmen Tejedor Rebeca S Sidhu-Mu?oz Luis Fernández-Lago Nieves Vizcaíno 《Veterinary research》2014,45(1):61
Brucella ovis causes ram contagious epididymitis, a disease for which a specific vaccine is lacking. Attenuated Brucella melitensis Rev 1, used as vaccine against ovine and caprine brucellosis caused by B. melitensis, is also considered the best vaccine available for the prophylaxis of B. ovis infection, but its use for this purpose has serious drawbacks. In this work, two previously characterized B. ovis attenuated mutants (Δomp25d and Δomp22) were evaluated in mice, in comparison with B. melitensis Rev 1, as vaccines against B. ovis. Similarities, but also significant differences, were found regarding the immune response induced by the three vaccines. Mice vaccinated with the B. ovis mutants developed anti-B. ovis antibodies in serum of the IgG1, IgG2a and IgG2b subclasses and their levels were higher than those observed in Rev 1-vaccinated mice. After an antigen stimulus with B. ovis cells, splenocytes obtained from all vaccinated mice secreted similar levels of TNF-α and IL12(p40) and remarkably high amounts of IFN-γ, a crucial cytokine in protective immunity against other Brucella species. By contrast, IL-1α -an enhancer of T cell responses to antigen- was present at higher levels in mice vaccinated with the B. ovis mutants, while IL-10, an anti-inflammatory cytokine, was significantly more abundant in Rev 1-vaccinated mice. Additionally, the B. ovis mutants showed appropriate persistence, limited splenomegaly and protective efficacy against B. ovis similar to that observed with B. melitensis Rev 1. These characteristics encourage their evaluation in the natural host as homologous vaccines for the specific prophylaxis of B. ovis infection. 相似文献