The biodiversity of dictyostelids in mountain forests: A case study in the French Alps     

Yoan Paillet  Michel Satre 《Pedobiologia》2010,53(5):337-341

Forest management can seriously modify the biodiversity of forest dwelling species, but the consequences are poorly known for certain taxa, particularly soil fauna, for which few studies have been published. We compared the biodiversity of dictyostelids cellular slime moulds in a managed and an unmanaged forest in the French Alps and analysed the influence of environmental factors on species richness and abundance of dictyostelids. To our knowledge, this study is the first one undertaken in the European Alps. We must better understand the influence of various environmental factors on the biodiversity of these organisms if we want to accurately define their functional role in the soil. In our study, dictyostelids showed lower levels of diversity compared to previously published results. The mean species richness of dictyostelids was marginally higher in unmanaged than in managed forests and biodiversity indices were significantly correlated with elevation and pH. This suggests that environmental factors have a predominant effect on the biodiversity of dictyostelids and that the effect of forest management is secondary.  相似文献   

Development of Plant Roots Network in Polluted Soils: An X-ray Computed Microtomography Investigation     

Nicolas Seignez  Arnaud Gauthier  Florias Mess  Celia Brunel  Michel Dubois  Jean Luc Potdevin 《Water, air, and soil pollution》2010,209(1-4):199-207

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Experimental udder infection with Escherichia coli. 2. Morphological changes of the epithelium in the area of the glands of the milk cistern and the large milk ducts     

P Sterba  G Michel  J Schulz 《Archiv fuer experimentelle veterinaermedizin》1990,44(5):740-756

Optical light, transmission, and scanning electron microscopy were used in investigations of epithelia in the glandular region of the milk cistern and greater lactiferous ducts and yielded the following findings, four and six hours from infection: degeneration and necrosis of epithelial cells, intraepithelial foreign cell infiltration (neutrophilic granulocytes, lymphocytes, macrophages), intra-epithelial oedema and locally delimited epithelial loss. The lesions differed by intensity in various regions, so that a distinction could be made among five froms of epithelial alterations. The epithelial cells revealed their capability of absorbing pathogenic material and storing it in cytoplasmic vacuoles. This was considered to reflect active involvement of epithelium in antibacterial defence, and consequently, to reflect the role played by epithelium as a defence barrier in the milk cistern and greater lactiferous ducts.  相似文献   

Hemagglutinating activity associated with bovine herpesvirus type 1   总被引：1，自引：0，他引：1  

Pierre Trpanier  Cecile Sguin  Yolande Bastien  Gaston Boulay  Gilles Lussier  Michel Trudel 《Veterinary microbiology》1985,10(6):517-523

Using C57BL/HPB mouse erythrocytes, hemagglutination has been observed with the Los Angeles and Colorado-1 strains of bovine herpesvirus type 1 and with 12 other Canadian field isolates as well. The specificity of the hemagglutination observed with the viral strains has been confirmed by a hemagglutination-inhibition assay.  相似文献   

Type IV secretion and Brucella virulence     

Maria Laura Boschiroli  Safia Ouahrani-Bettache  Vincent Foulongne  Sylvie Michaux-Charachon  Gisele Bourg  Annick Allardet-Servent  Chantal Cazevieille  Jean-Phillipe Lavigne  Jean Pierre Liautard  Michel Ramuz  David O&#x;Callaghan 《Veterinary microbiology》2002,90(1-4)

The type IV secretion system, encoded by the virB region, is a key virulence factor for Brucella. The 12 genes of the region form an operon that is specifically induced by phagosome acidification in cells after phagocytosis. We speculate that the system serves to secrete unknown effector molecules, which allow Brucella to pervert the host cell endosomal pathways and to create a novel intracellular compartment in which it can replicate.  相似文献   

Plant transposable elements,with an emphasis on grass species     

Fran?ois?Sabot  Delphine?Simon  Michel?BernardEmail author 《Euphytica》2004,139(3):227-247

Transposable elements are presents in all known genomes so far, and have the faculty of changing their genomic location and/or number of copies within the genome. They are mobile endogenous genetic elements, with a large variety of structure and transposition mechanism. In crops, they compose the major part of the nucleic DNA, up to 80% in some cereals like maize and wheat. Despite their omnipresence, they are largely unknown and uncharacterized within the Poaceae family. In this review, we describe a possible classification of the elements present in this family, some of their known transposition mechanism, their known activity and possible action in crops, and their possible origin.  相似文献   

Metaphase-I analysis of a Triticum aestivum x T. monococcum hybrid by the C-banding technique     

Juan M. González  Sylvie Bernard  Michel Bernard 《Euphytica》1993,68(3):187-192

Summary The meiotic pairing behaviour at metaphase I of a Triticum aestivum×Triticum monococcum hybrid has been studied by means of the C-banding technique to ascertain the homology between the chromosomes in the A genome of the two species. The technique allowed the A and B genome chromosomes and the 2D, 3D and 5D chromosomes to be identified. Differences in the level of chromosome pairing in the A genome were noted. The T. monococcum 4A chromosome did not pair with any of the T. aestivum chromosomes in any of the metaphase I cells analysed. Two reciprocal translocations between the 2B and 2D chromosomes on one side and the 2A and 3D on the other side have been identified. The usefulness of the C-banding technique in the study of chromosome homology among species related to wheat is discussed.  相似文献   

Interpretation probabilistique de la notion — limite admissible     

Michel Benarie 《Water, air, and soil pollution》1974,3(4):451-460

The usual procedure to obtain toxicological information is to link an effect with the frequency of its occurrence in a population. The most widely known example is the LD₅₀ As this general and obvious point of view has not always been heeded in the study of the health effects of air pollution, its consequent use is advocated and exemplified here. The customary concentration-duration diagrams, with an effect as parameter, lack the essential piece of information, which is the frequency with which that effect occurs. The paper starts with the available concentration-duration-frequency of effect data. With their help, a tridimensional diagram may be constructed. As observations containing such complete set of data are rather scarce, a few geometrical rules are shown, which allow interpolations and internal checks, thus somewhat extending the data interpretation. Any section through a constant frequency plane in this three dimensional representation defines unequivocal standards. The probability of the occurrence of a given effect is linked to a deliberate choice, in a fully analogues, quantitative way, as security factors in the engineering sciences. Most of the published clinical, symptomatological, etc., data in air pollution do not contain information linking the frequency of an effect to the total population. That is the reason why there still are debates about standards: no inferences using the simple, objective graphical tool outlined here can be drawn. Because of the scarcity of adequate data, the present attempt is not one of proposing ambient standards, but rather one to outline an approach: how such standards might be defined.  相似文献   

Effects of type of added salt and ionic strength on physicochemical and functional properties of casein isolates produced by electroacidification   总被引：1，自引：0，他引：1  

Bazinet L  Gendron C  Ippersiel D  René-Paradis J  Tétreault C  Beaudry J  Britten M  Mahdavi B  Amiot J  Lamarche F 《Journal of agricultural and food chemistry》2002,50(23):6875-6881

A procedure developed for soybean protein precipitation which was based on electrodialysis was tested for the production of acid casein from reconstituted skim milk. In a previous paper, the performance of bipolar membrane electroacidification (BMEA) was evaluated under different conditions of ionic strength (micro(added) = 0, 0.25, 0.5, or 1.0 M) and added salt (CaCl(2), NaCl, or KCl) (1). The aim of this study, which is the complement of the work on evaluation of BMEA performance, was to evaluate the functionality of the protein isolates produced by BMEA and to compare the BMEA isolates to commercial isolates and an isolate produced by chemical acidification. It was not possible to show differences between the functional properties of isolates produced by BMEA, except at 1 M CaCl(2) micro(added), due to the variability of the isolates. However, the results showed that it is possible to obtain isolates similar to commercial isolates and that the addition of salt during the process does not induce variations in functional properties. From results on mineral concentrations, it appeared that the addition of monovalent cations did not influence the retention of monovalent or divalent cations in the BMEA isolates, while addition of divalent cations (CaCl(2)) influenced the retention of magnesium. According to previous results on evaluation of BMEA performances under different conditions of ionic strength and added salt, the difference observed for the BMEA isolate produced at 1.0 M CaCl(2) was confirmed.  相似文献   

封丘地区土壤水分平衡研究 Ⅳ.雨养条件下三个不同湿度麦季的小麦耗水量与水分利用率          下载免费PDF全文

陈志雄  VauclinMichel 《土壤学报》1991,28(4):396-403

根据水量平衡方程式计算,雨养麦田三个试验麦季的耗水量分别为435.5、326和293.8mm,它们可代表该区过湿、一般和干旱年分的小麦耗水量.小麦地上部分生物量(茎杆+籽实)与其耗水量成正比,以第一麦季为100,第二、第三麦季分别为85和70;但籽实产量的反应与地上部生物量的反应并不一致,它们分别为100、102、70,以第二麦季最高.由于该麦季的耗水量相对较少,故有很高的水分利用率(1.73×10^-3kg/1)为华北地区所罕见.在耗水量中,土嚷储水的贡献约占50%.在降雨少而土壤储水丰足的年份,其贡献高达60%,是小麦水分的重要来源.在充分施肥条件下,小麦的水分利用率≥1.26×10^-3kg/1,它是建立预测小麦产量的经验模型的重要参数.  相似文献