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Alvarez M Huygens D Díaz LM Villanueva CA Heyser W Boeckx P 《Plant, cell & environment》2012,35(1):126-135
Acid phosphatase (ACP) enzymes are involved in the mobilization of soil phosphorus (P) and polyphosphate accumulated in the fungal tissues of ectomycorrhizal roots, thereby influencing the amounts of P that are stored in the fungus and transferred to the host plant. This study evaluated the effects of ectomycorrhizal morphotype and soil fertility on ACP activity in the extraradical mycelium (ACP(myc)), the mantle (ACP(mantle)) and the Hartig net region (ACP(Hartig)) of ectomycorrhizal Nothofagus obliqua seedlings. ACP activity was quantified in vivo using enzyme-labelled fluorescence-97 (ELF-97) substrate, confocal laser microscopy and digital image processing routines. There was a significant effect of ectomycorrhizal morphotype on ACP(myc), ACP(mantle) and ACP(Hartig), while soil fertility had a significant effect on ACP(myc) and ACP(Hartig). The relative contribution of the mantle and the Hartig net region to the ACP activity on the ectomycorrhizal root was significantly affected by ectomycorrhizal morphotype and soil fertility. A positive correlation between ACP(Hartig) and the shoot P concentration was found, providing evidence that ACP activity at the fungus:root interface is involved in P transfer from the fungus to the host. It is concluded that the spatial distribution of ACP in ectomycorrhizas varies as a function of soil fertility and colonizing fungus. 相似文献
24.
Kevin Lambeets Frederik Hendrickx Stijn Vanacker Kris Van Looy Jean-Pierre Maelfait Dries Bonte 《Biodiversity and Conservation》2008,17(13):3133-3148
We assessed the composition of spider and carabid beetle assemblages along river banks from the Common Meuse (Belgium) to
determine their relationships with local topographical and landscape-related characteristics. Data were gathered with pitfall
traps in 1998 and explored by ordination and grouping methods. Our analysis revealed that the presence of xerothermic spider
species was limited to scarcely covered, less dynamic gravel banks. Riparian spider species were found on frequently flooded
as well as on rather elevated and high gravel banks, while riparian carabid beetles were dominant on all sampled banks. The
level of flooding disturbance, the vegetation density and the presence of silt appeared to be the most important environmental
determinants of spider and carabid beetle assemblage structure. Consequently, local environmental factors influence species
occurrence patterns in a similar way for the two investigated arthropod groups. Nevertheless, distinct ecological groups are
differently ordered along the prime environmental gradients. Nature management should therefore consider the conservation,
restoration and connectivity of both dynamic and more elevated banks in order to obtain a high degree of local and regional
heterogeneity throughout the river system. 相似文献
25.
H M Rajh J H Uitzetter L W Westerhuis C L van den Dries G I Tesser 《International journal of peptide and protein research》1979,14(1):68-79
In order to investigate the special function of tryptophan in peptide hormones, six tryptophan analogues have been synthesized, in which structural resemblance has been grossly retained and potentially essential properties have only partially been varied. The L-enantiomers have been isolated after enzymatic digestion of racemic dipeptide derivatives, and charge-transfer properties of the compounds have been studied. 相似文献
26.
Bram Dhondt Beatrijs Bossuyt Maurice Hoffmann Dries Bonte 《Basic and Applied Ecology》2008,9(5):542-549
The two-phase dispersal event in which dung beetles move seeds after endozoochory is often assumed to be advantageous for plant regeneration. Because seeds are expected to end up in favourable and safe germination sites, it is considered as an example of directed dispersal. However, literature so far is restricted to tropical rain forest ecosystems, while data for temperate regions are lacking. In this study, the effect of dung beetles on seedling establishment of endozoochorically dispersed seeds is evaluated for a temperate grassland ecosystem. We performed a field experiment in which cages excluded dung beetles from horse and cattle dung samples with mixed-in grass seeds. Seed germination from these samples was significantly higher than that from samples which were accessible to dung beetles. This indicates that the effect of dung beetles on short-term seedling establishment was negative, which contrasts with the patterns found for large-seeded species used in tropical studies. This is most likely attributed to the lack of roller species and the larger depth at which tunneling Geotrupes species bury seeds. 相似文献
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B. De Corte D. Dries W. Verstraete P. Stevens L. Goossens P. De Vos J. De Ley 《Biotechnology letters》1989,11(8):583-588
Summary The metabolite pattern of batch cultures ofLactobacillus
casei LMG 6400,Clostridium
butyricum LMG 1213t1 andEscherichia
coli LMG 2093 was effected only for the latter organism when the H2 partial pressure was below 1 atmosphere: high hydrogen partial pressures increased the formate formation, low pressures gave rise to increased acetate production and higher cell yields. 相似文献
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Flocculation of microalgae using cationic starch 总被引:2,自引:0,他引:2
Dries Vandamme Imogen Foubert Boudewijn Meesschaert Koenraad Muylaert 《Journal of applied phycology》2010,22(4):525-530
Due to their small size and low concentration in the culture medium, cost-efficient harvesting of microalgae is a major challenge.
We evaluated the potential of cationic starch as a flocculant for harvesting microalgae using jar test experiments. Cationic
starch was an efficient flocculant for freshwater (Parachlorella, Scenedesmus) but not for marine microalgae (Phaeodactylum, Nannochloropsis). At high cationic starch doses, dispersion restabilization was observed. The required cationic starch dose to induce flocculation
increased linearly with the initial algal biomass concentration. Of the two commercial cationic starch flocculants tested,
Greenfloc 120 (used in wastewater treatment) was more efficient than Cargill C*Bond HR 35.849 (used in paper manufacturing).
For flocculation of Parachlorella using Greenfloc 120, the cationic starch to algal biomass ratio required to flocculate 80% of algal biomass was 0.1. For
Scenedesmus, a lower dose was required (ratio 0.03). Flocculation of Parachlorella using Greenfloc 120 was independent of pH in the pH range of 5 to 10. Measurements of the maximum quantum yield of PSII suggest
that Greenfloc 120 cationic starch was not toxic to Parachlorella. Cationic starch may be used as an efficient, nontoxic, cost-effective, and widely available flocculant for harvesting microalgal
biomass. 相似文献