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Tadra-Sfeir MZ Souza EM Faoro H Müller-Santos M Baura VA Tuleski TR Rigo LU Yates MG Wassem R Pedrosa FO Monteiro RA 《Applied and environmental microbiology》2011,77(6):2180-2183
Five thousand mutants of Herbaspirillum seropedicae SmR1 carrying random insertions of transposon pTnMod-OGmKmlacZ were screened for differential expression of LacZ in the presence of naringenin. Among the 16 mutants whose expression was regulated by naringenin were genes predicted to be involved in the synthesis of exopolysaccharides, lipopolysaccharides, and auxin. These loci are probably involved in establishing interactions with host plants. 相似文献
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BENOÎT O. L. DEMARS JACQUELINE M. POTTS MICHÈLE TRÉMOLIÈRES GABRIELLE THIÉBAUT NATHALIE GOUGELIN VINCENT NORDMANN 《Freshwater Biology》2012,57(8):1745-1759
1. Recent studies have demonstrated that there is generally no unambiguous relationship between plant species composition and specific environmental conditions in rivers. Nevertheless, indices of environmental pressures based on macrophytes are flourishing, because of the requirements of the Water Framework Directive (WFD). 2. We first reviewed nine such indices against 13 criteria for bioindicators. Then, using data from France and England, we tested whether the IBMR (Macrophyte Biological Index for Rivers) and LEAFPACS (predictions and classification system for macrophytes) methods could reliably indicate nutrient and hydromorphological pressures. Finally, we used an improved bootstrapping method to estimate accuracy. 3. Currently, most indices lack ecological meaning for a variety of reasons, including partial sampling (backwaters are excluded); reliance on list of taxa (there are identification difficulties) rather than structure and functions; correlation rather than causation; application within a limited biogeographical area; reliance on ‘expert’ judgement; high precision but poor accuracy; poorly defined reference conditions; lack of independent tests; and an inability to discriminate reliably between the target pressures of interest from confounding background variables. 4. IBMR was a far better indicator of pH (or HCO3‐pCO2) than it was of soluble reactive phosphorus, SRP (or SRP‐NH4). While there was a highly significant correlation between IBMR and SRP after removing the effect of pH, the relationship was weak (r2 = 0.08, n = 215, P < 0.001). 5. LEAFPACS is a multi‐metric method summing up five individual indices, each compliant with the WFD. Its individual metrics were not better correlated with nutrient and hydromorphological pressures (with r2 < 0.1, n = 62, P < 0.05) than was the IBMR. The meaning of the overall metric is questionable. 6. There are problems in determining the precision of the indices, owing to uncertainties in recording, but they are less than the uncertainties in determining accuracy (because species optima and tolerances are sometimes poorly known). 7. Reliable information is needed to improve the state of our rivers. Macrophyte indices are able to detect statistically significant pressures from a large population of sites but cannot be applied at specific sites, as required by the WFD, owing to large uncertainties and low explanatory power. Typically, more than 90% of the variability in macrophyte indices is attributed to factors other than human pressure. The WFD would be better served by a simpler, holistic approach based on our current mechanistic understanding of river processes. These findings are likely to apply also to other taxonomic groups (macroinvertebrates, diatoms, fish) used in the assessment of purported ecological quality and to palaeolimnological measures of reference status. 相似文献
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Intra-specific heterogeneity of the rDNA internal transcribed spacer in the Simulium damnosum (Diptera: Simuliidae) complex 总被引:3,自引:0,他引:3
The internal transcribed spacer (ITS) of the rRNA gene cluster has been
used as a model for the study of the action of concerted evolution and
molecular drive on repeated sequence families. In contrast to this general
finding, preliminary DNA sequence analysis of cloned representatives of the
ITS from the West African black fly species complex Simulium damnosum s.1.
demonstrated extensive intra-individual and intra-specific polymorphisms.
Variability in the ITS was primarily confined to the ITS1 domain. The
degree and type of intra-individual and intra-specific variability within
the ITS was further characterized using gel electrophoresis, DNA
hybridization, and heteroduplex analysis of the PCR products generated from
the ITS1 domain. ITS1 copies from individual S. damnosum s.1. differed in
length and sequence composition. These results, when taken together,
demonstrate that a large degree of intra-individual and intra-specific
heterogeneity exists in the ITS of S. damnosum s.1. The intra-individual
heterogeneity was greater in the savanna-dwelling than forest-dwelling
sibling species of S. damnosum s.1. This heterogeneity may be due in part
to inter-breeding among sympatric sibling species, coupled with disturbance
of S. damnosum s.1. populations resulting from intensive vector control
efforts.
相似文献
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Deepa Indira Shankara Narayanan Varadarajan Santhik Subhasingh Lupitha Asha Lekshmi Krupa Ann Mathew Aneesh Chandrasekharan Prakash Rajappan Pillai Ishaque Pulikkal Kadamberi Indu Ramachandran Hari Sekar Anurup Kochucherukkan Gopalakrishnan Santhoshkumar TR 《European journal of cell biology》2018,97(1):1-14
The selective autophagic removal of mitochondria called mitophagy is an essential physiological signaling for clearing damaged mitochondria and thus maintains the functional integrity of mitochondria and cells. Defective mitophagy is implicated in several diseases, placing mitophagy as a target for drug development. The identification of key regulators of mitophagy as well as chemical modulators of mitophagy requires sensitive and reliable quantitative approaches. Since mitophagy is a rapidly progressing event and sub-microscopic in nature, live cell image-based detection tools with high spatial and temporal resolution is preferred over end-stage assays. We describe two approaches for measuring mitophagy in mammalian cells using stable cells expressing EGFP-LC3 – Mito-DsRed to mark early phase of mitophagy and Mitochondria-EGFP – LAMP1-RFP stable cells for late events of mitophagy. Both the assays showed good spatial and temporal resolution in wide-field, confocal and super-resolution microscopy with high-throughput adaptable capability. A limited compound screening allowed us to identify a few new mitophagy inducers. Compared to the current mitophagy tools, mito-Keima or mito-QC, the assay described here determines the direct delivery of mitochondrial components to the lysosome in real time mode with accurate quantification if monoclonal cells expressing a homogenous level of both probes are established. Since the assay described here employs real-time imaging approach in a high-throughput mode, the platform can be used both for siRNA screening or compound screening to identify key regulators of mitophagy at decisive stages. 相似文献
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Eduardo Balsanelli Thalita Regina Tuleski Valter Antonio de Baura Marshall Geoffrey Yates Leda Satie Chubatsu Fabio de Oliveira Pedrosa Emanuel Maltempi de Souza Rose Adele Monteiro 《PloS one》2013,8(10)
Herbaspirillum seropedicae is a plant growth-promoting diazotrophic betaproteobacterium which associates with important crops, such as maize, wheat, rice and sugar-cane. We have previously reported that intact lipopolysaccharide (LPS) is required for H. seropedicae attachment and endophytic colonization of maize roots. In this study, we present evidence that the LPS biosynthesis gene waaL (codes for the O-antigen ligase) is induced during rhizosphere colonization by H. seropedicae. Furthermore a waaL mutant strain lacking the O-antigen portion of the LPS is severely impaired in colonization. Since N-acetyl glucosamine inhibits H. seropedicae attachment to maize roots, lectin-like proteins from maize roots (MRLs) were isolated and mass spectrometry (MS) analysis showed that MRL-1 and MRL-2 correspond to maize proteins with a jacalin-like lectin domain, while MRL-3 contains a B-chain lectin domain. These proteins showed agglutination activity against wild type H. seropedicae, but failed to agglutinate the waaL mutant strain. The agglutination reaction was severely diminished in the presence of N-acetyl glucosamine. Moreover addition of the MRL proteins as competitors in H. seropedicae attachment assays decreased 80-fold the adhesion of the wild type to maize roots. The results suggest that N-acetyl glucosamine residues of the LPS O-antigen bind to maize root lectins, an essential step for efficient bacterial attachment and colonization. 相似文献
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