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41.
Karel?Dhondt Pascal?BoeckxEmail author Georges?Hofman Oswald?Van?Cleemput 《Biology and Fertility of Soils》2004,40(4):243-251
The aim of this study was to investigate temporal and spatial patterns of denitrification enzyme activity (DEA) and nitrous oxide (N2O) fluxes in three adjacent riparian sites (mixed vegetation, forest and grass). The highest DEA was found in the surface (0–30 cm) soil and varied between 0.7±0.1 mg N kg–1 day–1 at 5°C and 5.9±0.4 mg N kg–1 day–1 at 15°C. There was no significant difference (P >0.05) between the DEA in the uppermost (0–30 cm and 60–90 cm) soil depths under different vegetation covers. In the two deepest (120–150 cm and 180–210 cm) soil depths the DEA varied between 0.0±0.0 mg N kg–1 day–1 at 5°C and 4.4±0.9 mg N kg–1 day–1 at 15°C and was clearly associated with the accumulation of buried organic carbon (OC). Two threshold values of OC were observed before DEA started to increase significantly, namely 5 and 25 g OC kg–1 soil at 10–15°C and 5°C, respectively. In the three riparian sites N2O fluxes varied between a net N2O uptake of –0.6±0.4 mg N2O-N m–2 day–1 and a net N2O emission of 2.5±0.3 mg N2O-N m–2 day–1. The observed N2O emission did not lead to an important pollution swapping (from water pollution to greenhouse gas emission). Especially in the mixed vegetation and forest riparian site highest N2O fluxes were observed upslope of the riparian site. The N2O fluxes showed no clear temporal trend. 相似文献
42.
Two species of Cryptosporidium are commonly identified in pigs: Cryptosporidium suis and Cryptosporidium pig genotype II. Detection of Cryptosporidium spp. is routinely based on molecular methods such as polymerase chain reaction (PCR) and subsequent restriction fragment length polymorphism (RFLP) or gene sequencing. However, most of these methods are hampered by low sensitivity to mixed infections. As a solution of this problem, novel species-specific primers were designed and tested in the present study. Sensitivity of our primers was identical to genus-specific primers, but more (1:48) mixed infections were detected using these species-specific primers on 477 DNA samples originating from naturally infected pigs of different age categories. Our results show differences in age-dependent susceptibility of pigs to the infection. Whereas C. suis was found in all tested categories of pigs (1-12 week of age and sows), Cryptosporidium pig genotype II was recorded only in animals older than 6 week of age. Usage of species-specific primers could help to better the understanding of epidemiology of pig specific Cryptosporidium spp. and its occurrence, which, on the basis of our results, is underestimated. 相似文献
43.
Karel Krovacek Marco Conte Patrizia Galderisi Giuseppe Morelli Attilio Postiglione Stefano Dumontet 《Comparative immunology, microbiology and infectious diseases》1993,16(4):267-272
In this case report from Italy we describe a fatal infection caused by A. hydrophila in a 39 yr old cirrhotic patient. This pathogen was isolated as a pure single culture from the patient's blood sample. The patient died on the second day of hospitalization from overwhelming sepsis. The A. hydrophila isolate was tested for different potential virulence properties, such as invasiveness, adherence, exotoxins production, presence of fimbriae and for the patterns of resistance to a variety of antimicrobial agents. Although, the Aeromonas species are infrequently reported as a cause of human infections, the present case study confirms the capability of these pathogens to induce serious human infections. 相似文献
44.
Relationships between measures of soil water availability, available soil macronutrients and site index of coastal Douglas fir were examined in 53 stands. Growing-season water-deficit was able to explain the most variation in site index of all soil water-balance measures examined (R2 = 0.42). Of all soil chemical properties examined, mineralizable N in the surface 30 cm of the mineral soil and in the forest floor accounted for the most variation in site index (R2 = 0.54). Multiple regression of the natural log of mineralizable N, and growing-season water-deficit on site index gave an R2 of 0.63. Use of mineralizable N as a measure of N availability is supported, and interactions between water-use efficiency and stand N status are suggested. 相似文献
45.
Davis WC Drbal K Mosaad AE Elbagory AR Tibary A Barrington GM Park YH Hamilton MJ 《Veterinary immunology and immunopathology》2007,119(1-2):123-130
Flow cytometry was used to screen a panel of 320 mAbs, submitted to the Animal Homologues Section of the HLDA8, for mAbs that recognize epitopes conserved on orthologous leukocyte differentiation antigens (LDA) in goats, lamas, and rabbits. Nineteen mAbs specific for CD11a (1), CD14 (3), CD18 (1), CD21 (1), CD29 (2), CD44 (2), CD47 (3), CD49d (1), CD172a (1), CD45RB (1), CD61 (1), RACT48A, and GBSP71A reacted with goat LDA. Twenty three mAbs specific for CD7 (1), CD9 (2), CD11a (1), CD14 (3), CD18 (4), CD29 (1), CD32 (1), CD44 (1), CD47 (4), CD49d (2), CD50 (1), CD80 (1), CD172a (1), and GBSP71A reacted with llama LDA. Eighteen mAbs specific for CD9 (2), CD11a (1), CD14 (2), CD18 (4), CD21 (1), CD44 (2), CD45RB (1), CD49d (1), CD209 (1), RACT48A, and GBSP71A reacted with rabbit LDA. The specificities of two cross reactive mAbs that recognize different conserved epitopes on all leukocytes in two species (RACT48A) and all three species (GBSP71A) have not been determined. The patterns of reactivity of most of the mAbs were consistent with patterns of reactivity noted on human leukocytes. The specificity of some cross reactive mAbs generated in non-human species were validated on human leukocytes. Further studies are needed to verify that CD7, CD32, CD45RB, CD50, and CD209 recognize orthologous molecules in the indicated species. 相似文献
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49.
Parvizi P Abdul-Careem MF Haq K Thanthrige-Don N Schat KA Sharif S 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2010,11(2):123-134
It is more than a century since Marek's disease (MD) was first reported in chickens and since then there have been concerted efforts to better understand this disease, its causative agent and various approaches for control of this disease. Recently, there have been several outbreaks of the disease in various regions, due to the evolving nature of MD virus (MDV), which necessitates the implementation of improved prophylactic approaches. It is therefore essential to better understand the interactions between chickens and the virus. The chicken immune system is directly involved in controlling the entry and the spread of the virus. It employs two distinct but interrelated mechanisms to tackle viral invasion. Innate defense mechanisms comprise secretion of soluble factors as well as cells such as macrophages and natural killer cells as the first line of defense. These innate responses provide the adaptive arm of the immune system including antibody- and cell-mediated immune responses to be tailored more specifically against MDV. In addition to the immune system, genetic and epigenetic mechanisms contribute to the outcome of MDV infection in chickens. This review discusses our current understanding of immune responses elicited against MDV and genetic factors that contribute to the nature of the response. 相似文献
50.
Karl-Johan Wetterwik Gunilla Trowald-Wigh Lise-Lotte Fernstr?m Karel Krovacek 《Acta veterinaria Scandinavica》2013,55(1):23