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141.
Clay minerals as a factor influencing the biochemical activity of soil microorganisms 总被引:1,自引:0,他引:1
Z. Filip 《Folia microbiologica》1973,18(1):56-74
The results of the study confirm the significance of clay minerals as a factor influencing the biochemical activity of soil
microorganisms. The soil microflora is influenced both by the direct effect of clays on the microbial cells and indirectly,
by their effect on the environment. The direct effect is projected into fundamental processes of the cycle of biogenic elements,
including humification processes. The character and mechanism of the effect depend on the species of microorganism, on the
quality and quantity of the mineral sorbents present in the soil and on other ecological factors. A further study will be
carried out to investigate different aspects of the influence of clay minerals on the incidence, growth and biochemical activity
of soil microorganisms. 相似文献
142.
The study was carried out in the years 2016–2017, five years after a windstorm which destroyed 1/3 of the protected beech forest area in the west of Poland. The community of centipedes in the area affected by the windstorm was depleted in terms of the species richness, diversity, and population density. The dominance structures were shortened and the species composition was rebuilt. The areas that proved to be the richest in terms of species richness and diversity among the sites affected by the windstorm were the one where windfallen trees were left and the other where beech trees had been planted by humans. In total, the quantitative and qualitative samples collected four times throughout a year featured 608 specimens from 11 species of two centipede orders – Lithobiomorpha and Geophilomorpha. Lithobius curtipes and L. forficatus were found in all of the investigated areas. L. pelidnus and L. piceus were captured at control sites exclusively. Only one species –L. erythrocephalus was found solely at the damaged site. The most numerous and most frequently found species in the community were L. curtipes, L. mutabilis, and Strigamia acuminata respectively. Although windstorms are natural phenomena their consequences may lead to significant changes in the community of the investigated soil animals. The importance of coarse woody debris, significantly contributing to the improvement and maintenance of species richness and diversity of Chilopoda, has once again been confirmed. 相似文献
143.
Niche shifts and range expansions along cordilleras drove diversification in a high‐elevation endemic plant genus in the tropical Andes 下载免费PDF全文
The tropical Andes represent one of the world's biodiversity hot spots, but the evolutionary drivers generating their striking species diversity still remain poorly understood. In the treeless high‐elevation Andean environments, Pleistocene glacial oscillations and niche differentiation are frequently hypothesized diversification mechanisms; however, sufficiently densely sampled population genetic data supporting this are still lacking. Here, we reconstruct the evolutionary history of Loricaria (Asteraceae), a plant genus endemic to the Andean treeless alpine zone, based on comprehensive population‐level sampling of 289 individuals from 67 populations across the entire distribution ranges of its northern Andean species. Partly incongruent AFLP and plastid DNA markers reveal that the distinct genetic structure was shaped by a complex interplay of biogeography (spread along and across the cordilleras), history (Pleistocene glacial oscillations) and local ecological conditions. While plastid variation documents an early split or colonization of the northern Andes by at least two lineages, one of which further diversified, a major split in the AFLP data correlate with altitudinal ecological differentiation. This suggests that niche shifts may be important drivers of Andean diversification not only in forest–alpine transitions, but also within the treeless alpine zone itself. The patterns of genetic differentiation at the intraspecific level reject the hypothesized separation in spatially isolated cordilleras and instead suggest extensive gene flow among populations from distinct mountain chains. Our study highlights that leveraging highly variable markers against extensive population‐level sampling is a promising approach to address mechanisms of rapid species diversifications. 相似文献
144.
145.
Dear DV Young DS Kazlauskaite J Meersman F Oxley D Webster J Pinheiro TJ Gill AC Bronstein I Lowe CR 《Biochimica et biophysica acta》2007,1774(7):792-802
Prion diseases, or transmissible spongiform encephalopathies (TSEs) are typically characterised by CNS accumulation of PrP(Sc), an aberrant conformer of a normal cellular protein PrP(C). It is thought PrP(Sc) is itself infectious and the causative agent of such diseases. To date, no chemical modifications of PrP(Sc), or a sub-population thereof, have been reported. In this study we have investigated whether chemical modification of amino acids within PrP might cause this protein to exhibit aberrant properties and whether these properties can be propagated onto unmodified prion protein. Of particular interest were post-translational modifications resulting from physiological conditions shown to be associated with TSE disease. Here we report that in vitro exposure of recombinant PrP to conditions that imitate the end effects of oxidative/nitrative stress in TSE-infected mouse brains cause the protein to adopt many of the physical characteristics of PrP(Sc). Most interestingly, these properties could be propagated onto unmodified PrP protein when the modified protein was used as a template. These data suggest that post-translational modifications of PrP might contribute to the initiation and/or propagation of prion protein-associated plaques in vivo during prion disease, thereby high-lighting novel biochemical pathways as possible therapeutic targets for these conditions. 相似文献
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147.
Francisco Zorrilla Filip Buric Kiran R Patil Aleksej Zelezniak 《Nucleic acids research》2021,49(21):e126
Metagenomic analyses of microbial communities have revealed a large degree of interspecies and intraspecies genetic diversity through the reconstruction of metagenome assembled genomes (MAGs). Yet, metabolic modeling efforts mainly rely on reference genomes as the starting point for reconstruction and simulation of genome scale metabolic models (GEMs), neglecting the immense intra- and inter-species diversity present in microbial communities. Here, we present metaGEM (https://github.com/franciscozorrilla/metaGEM), an end-to-end pipeline enabling metabolic modeling of multi-species communities directly from metagenomes. The pipeline automates all steps from the extraction of context-specific prokaryotic GEMs from MAGs to community level flux balance analysis (FBA) simulations. To demonstrate the capabilities of metaGEM, we analyzed 483 samples spanning lab culture, human gut, plant-associated, soil, and ocean metagenomes, reconstructing over 14,000 GEMs. We show that GEMs reconstructed from metagenomes have fully represented metabolism comparable to isolated genomes. We demonstrate that metagenomic GEMs capture intraspecies metabolic diversity and identify potential differences in the progression of type 2 diabetes at the level of gut bacterial metabolic exchanges. Overall, metaGEM enables FBA-ready metabolic model reconstruction directly from metagenomes, provides a resource of metabolic models, and showcases community-level modeling of microbiomes associated with disease conditions allowing generation of mechanistic hypotheses. 相似文献
148.
Tanja Žuna Pfeiffer Dubravka Špoljarić Maronić Vanda Zahirović Filip Stević Melita Mihaljević 《Biodiversity and Conservation》2017,26(2):439-460
Intensive human activities have resulted in a critical reduction of grasslands in Croatia, one of the richest Europian countries in terms of biodiversity. Sub-Pannonic steppic grasslands are very rare, only few occur in the continental part of Croatia and most of them are protected as NATURA 2000 sites. We studied vascular flora of the Sub-Pannonic stepic grassland with the aim to examine the changes in plant communities 15 years from the mowing application. Results showed that hand mowing once per year at the end of vegetation season increased the species diversity as well as the number of medium and low growth taxa. The critically endangered, nearly threatened and vulnerable species remained preserved. The occurrence of trees, shrubs and invasive species as a consequence of succession and anthropogenic influences could be important threat for steppe-like grassland flora. From a conservation point of view infrequent mowing regime could be an effective management tool, although it needs to be adapted to regional and local circumstances for maintaining high biodiversity of steppe-like grasslands and valuable plant species. 相似文献
149.
Filip Fratev 《Journal of biomolecular structure & dynamics》2017,35(3):476-485
The structural and dynamical properties of PPARγ receptor in a complex with either partial or full agonists have been intensively studied but little is known about the receptor antagonistic conformation. A composition of microsecond accelerated molecular dynamics (aMD) simulation show that like partial agonists a non-covalent PPARγ full antagonist can bind in different modes of similar population size and free energies of binding. Four different and periodically exchanging ligand conformations are detected and described. The studied antagonist interacts with different receptor substructures and affects both the co-activator and the Cdk5 phosphorylation sites and, presumably, the natural complex with the DNA. However, no significant changes in the conformational states of the activation helix 12, and in particular an antagonist orientation, have been recorded. Finally, our results show also that the aMD approach can be successfully used in recovering the possible binding modes, considering fully the receptor flexibility, and is not dependent on the starting conformation. 相似文献
150.