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201.
The spatial structure of tropical forest stands under different management conditions was modeled as a series of different spatial point processes. Spatial patterns were first assessed by K-function analyses to help choose a point process appropriate for observed patterns. The homogenous Neyman–Scott process accurately described live tree distribution in clear cut areas, where tree patterns tended to be aggregated. Parameters were estimated by minimizing Diggle's modified least squares criterion, and goodness-of-fit was assessed by comparison to confidence envelopes constructed by Monte Carlo simulation. Parameter estimates can be interpreted to help understand the ecological processes influencing re-colonization of disturbed areas. The inhomogeneous Poisson process was investigated for simulating the spatial pattern of ingrowth trees in lower canopy strata. The intensity function of this process was inversely proportional to variables representing canopy density. As assessed by Monte Carlo generation of confidence envelopes, the inhomogeneous Poisson process successfully portrayed the influence of canopy structure on understory plant distribution in most stands. Tree mortality was modeled as a thinning process in which the probability of individual tree mortality was conditional on subject tree attributes and competitive environment. The thinning function took the form of a generalized linear model with a binomial error distribution and logit link function. In most stands, tree neighborhood variables were powerful predictors of mortality, but they were not important predictors in all plots. This suggests that the surrounding forest structure of a subject tree has considerable influence on its morality, but competition is not the sole cause of tree morality in tropical forests.  相似文献   
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Group A rotavirus (RV) and coronavirus (CV) are common viral pathogens associated with neonatal diarrhoea in numerous animal species. The purpose of this work was to investigate the presence of these viral agents in two farm populations of captured guanacos (Lama guanicoe) in the Argentinean Patagonia region, that developed severe diarrhoea outbreaks. Stool and serum samples were analysed for RV and bovine CV antigen and antibody by enzyme‐linked immunosorbent assay. Rotavirus was detected in faeces from two new‐born guanacos with acute diarrhoea, one in each farm. After electrophoretic analysis, each isolated strain, showed a distinctive long dsRNA electropherotype characteristic of group A rotaviruses (4:2:3:2). In addition, 95% (38 of 40) of the sampled animals were positive for RV antibodies, suggesting a high prevalence of RV infection in the populations tested. No evidence of CV circulation by antigen or antibody analysis was observed. To our knowledge, this is the first report of the detection and isolation of RV associated with neonatal diarrhoea in Lama guanicoe.  相似文献   
204.
The Veterinary Control Act of 1844 was the first to regulate in entirety the control of infectious diseases in animals and questions of sanitary inspection of animal food products in the Kingdom of Poland. The act listed explicit procedures regarding diagnostics, control and eradication of diseases as well as concerning animal food product inspection. The act required that animal owners become familiar with symptoms of animal diseases, their methods of control and that they prevent their spreading. The obligations of veterinarians, state physicians and administrative control bodies in the control of animal diseases were specified by the act. Besides the main text on the control of diseases and meat inspection the act also contains elements of food law, some norms concerning public law and order (e.g. requirements concerning dogs) and even some regulations on animal protection.  相似文献   
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A total of 35 ejaculates were studied in order to assess the suitability of porcine semen for freezing according to the ejaculate characteristics. The effects of the freezing procedure were identified; a decrease in motility and acrosome quality was found after thawing. The best results on motility were linked to the ejaculates with a volume of less than 100 ml of the sperm‐rich fraction, a concentration lower than 450 × 106 spermatozoa/ml and an agglutination score below 2. However, the best normal apical ridge (NAR) was found when the volume of the sperm‐rich fraction was greater than 150 ml. For this reason, an intermediate volume of the sperm‐rich fraction of the ejaculate for the best motility and the best NAR, a concentration lower than 450 × 106 spermatozoa/ml and a rate of agglutination below 2 should provide the best quality after freezing. This study also attempted to determine whether a positive effect of ejaculate selection on the overall freezing performance might be expected.  相似文献   
207.
Esophageal-pharyngeal fluids from 53 free-ranging marsh deer (Blastocerus dichotomus) captured for a research program in the state of Mato Grosso do Sul, Brazil, were assayed for tuberculosis. Total DNA was extracted. amplified by polymerase chain reaction using specific primers for Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis, M. microti, and M. africanum), and observed by agarose gel electrophoresis stained with ethidium bromide. All samples were negative. This, along with necropsy and histopathology data, suggests that these animals are not shedding and probably do not have active disease.  相似文献   
208.
Anaplasmosis, caused by Anaplasma marginale, results in significant economic losses of cattle in tropical and subtropical regions worldwide. Six major surface proteins (MSPs) were well characterized and designated as MSP1, MSP2, MSP3, MSP4, and MSP5. The objective of this study was to evaluate the humoral immune response of BALB/c mice against the recombinant MSPs, incorporated into immunostimulating complex (ISCOM). The recombinant proteins purified by Ni-NTA columns were incorporated into ISCOM and ISCOMATRIX by the lipid film hydration method. BALB/c mice immunized with ISCOM/rMSPs and ISCOMATRIX/rMSPs vaccines produced whole IgG, IgG1, and IgG2a, in contrast to the negative groups (PBS and ISCOMATRIX adjuvant). All groups that received antigen responded specifically against the rMSPs by Western blotting, showing the rMSP1a (60-105kDa), rMSP1b (100kDa), rMSP4 (47kDa), and rMSP5 (29kDa). Additional studies will have to be performed in cattle to evaluate the humoral and cellular mechanisms of this subunit vaccine and their possible use as protective vaccines against homologous and heterologous strains of A. marginale.  相似文献   
209.
Mining activities are related to relevant environmental pollution issues that should be controlled. We used sequential extractions to fractionate Cd, Cu, Ni, Pb and Zn retained on unamended or mussel shell‐amended mine soil samples, all of them treated with a mixture of the five heavy metals (total metal concentration of 1·57 mmol L−1), after 1, 7 and 30 days of incubation. In addition, we used the stirred flow chamber technique to study the release of each of the five heavy metals from these different unamended and shell‐amended soil samples. The results indicate that the shell amendment caused a decrease in the most soluble fraction, while increasing the most recalcitrant (least mobile) fraction. With equivalent implications, the stirred flow chamber experiments showed that mussel shell amendment was associated to a decrease in heavy metal release and increased retention. The highest mussel shell dose and incubation time caused the most relevant changes in pH values and thus in metal retention, also indicating the importance of pH modifications in the mechanism of retention acting in the amended samples. In view of these results, the use of mussel shell amendment can be encouraged to increase heavy metal retention in acid mine soils, in order to minimise risks of environmental pollution. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
210.
Isolated plant microspores, when stressed and cultured in vitro, can be diverted from their normal gametophytic pathway towards sporophytic development, with the formation of haploid embryos and ultimately doubled-haploid plants. This process is called androgenesis or microspore embryogenesis, and is widely used in plant breeding programmes to generate homozygous lines for breeding purposes. Protocols for the induction of microspore embryogenesis and the subsequent regeneration of doubled haploid (DH) plants have been successfully developed for more than 200 species. These practical advances stand in stark contrast to our knowledge of the underlying molecular genetic mechanism controlling this process. The majority of information regarding the genetic and molecular control of the developmental switch from gametophytic to sporophytic development has been garnered from four intensely studied (crop) plants comprising two dicotyledonous species, rapeseed (Brassica napus) and tobacco (Nicotiana tabacum), and two monocotyledonous species, wheat (Triticum aestivum) and barley (Hordeum vulgare). In these species the efficiency of microspore embryogenesis is very high and reproducible, making them suitable models for molecular studies. In the past, molecular studies on microspore embryogenesis have focussed mainly on the identification of genes that are differentially expressed during this developmental transition and/or early in embryo development, and have identified a number of genes whose expression marks or predicts the developmental fate of stressed microspores. More recently, functional genomics approaches have been used to obtain a broad overview of the molecular processes that take place during the establishment of microspore embryogenesis. In this review we summarise accumulated molecular data obtained in rapeseed, tobacco, wheat and barley on embryogenic induction of microspores and define common aspects involved in the androgenic switch.  相似文献   
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