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Anne S Rasmussen Henrik Lauridsen Christoffer Laustsen Bjarke G Jensen Steen F Pedersen Lars Uhrenholt Lene WT Boel Niels Uldbjerg Tobias Wang Michael Pedersen 《BMC physiology》2010,10(1):3
Background
In biomedical sciences, ex vivo angiography is a practical mean to elucidate vascular structures three-dimensionally with simultaneous estimation of intravascular volume. The objectives of this study were to develop a magnetic resonance (MR) method for ex vivo angiography and to compare the findings with computed tomography (CT). To demonstrate the usefulness of this method, examples are provided from four different tissues and species: the human placenta, a rice field eel, a porcine heart and a turtle. 相似文献12.
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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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Lauridsen H Hansen K Wang T Agger P Andersen JL Knudsen PS Rasmussen AS Uhrenholt L Pedersen M 《PloS one》2011,6(3):e17879
Animal anatomy has traditionally relied on detailed dissections to produce anatomical illustrations, but modern imaging modalities, such as MRI and CT, now represent an enormous resource that allows for fast non-invasive visualizations of animal anatomy in living animals. These modalities also allow for creation of three-dimensional representations that can be of considerable value in the dissemination of anatomical studies. In this methodological review, we present our experiences using MRI, CT and μCT to create advanced representation of animal anatomy, including bones, inner organs and blood vessels in a variety of animals, including fish, amphibians, reptiles, mammals, and spiders. The images have a similar quality to most traditional anatomical drawings and are presented together with interactive movies of the anatomical structures, where the object can be viewed from different angles. Given that clinical scanners found in the majority of larger hospitals are fully suitable for these purposes, we encourage biologists to take advantage of these imaging techniques in creation of three-dimensional graphical representations of internal structures. 相似文献