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191.
Louise Berg Johan Rönnelid Carani B Sanjeevi Jon Lampa Lars Klareskog 《Arthritis research & therapy》1999,2(1):75
192.
Rafael Zárate Johan Memelink Robert van der Heijden Robert Verpoorte 《Biotechnology letters》1999,21(11):997-1002
In vitro propagation of Catharanthus roseus was achieved using nodal explants. Bud induction was best on medium containing 1.0 mg benzyl aminopurine l–1. Hardening of rooted shoots to soil was very successful with 98% survival. Genetically transformed C. roseus plantlets were obtained after bombardment of nodal explants, which were then micropropagated, with DNA coated particles with green fluorescent protein (GFP) or -glucuronidase (GUS) reporter genes. Histological studies showed that the gene insertion method proved effective with many cells and different tissues displaying the reporter gene signals, showing that gene expressions were rather stable. 相似文献
193.
194.
't Hoen PA Turk R Boer JM Sterrenburg E de Menezes RX van Ommen GJ den Dunnen JT 《Nucleic acids research》2004,32(4):e41
In two-colour microarrays, the ratio of signal intensities of two co-hybridized samples is used as a relative measure of gene expression. Ratio-based analysis becomes complicated and inefficient in multi-class comparisons. We therefore investigated the validity of an intensity-based analysis procedure. To this end, two different cRNA targets were hybridized together, separately, with a common reference and in a self-self fashion on spotted 65mer oligonucleotide microarrays. We found that the signal intensity of the cRNA targets was not influenced by the presence of a target labelled in the opposite colour. This indicates that targets do not compete for binding sites on the array, which is essential for intensity-based analysis. It is demonstrated that, for good-quality arrays, the correlation of signal intensity measurements between the different hybridization designs is high (R > 0.9). Furthermore, ratio calculations from ratio- and intensity-based analyses correlated well (R > 0.8). Based on these results, we advocate the use of separate intensities rather than ratios in the analysis of two-colour long-oligonucleotide microarrays. Intensity-based analysis makes microarray experiments more efficient and more flexible: It allows for direct comparisons between all hybridized samples, while circumventing the need for a reference sample that occupies half of the hybridization capacity. 相似文献
195.
Johan?UddlingEmail author H?kan?Pleijel Per?Erik?Karlsson 《Trees - Structure and Function》2004,18(6):686-695
Leaf diffusive conductance for water (gl) and twig xylem pressure (xt) was measured in juvenile silver birch, Betula pendula, under field conditions in southern Sweden. Data from one site were used to parameterise two different multiplicative models for gl (dependent data), and measurements from another site were used to validate these models (independent data). In addition, experiments were performed in controlled environments to validate the gl response functions used in the models. The driving variables in the D-model were photosynthetic photon flux density, air temperature and water vapour pressure deficit of the air (Da), while the DH-model also included the accumulated hours after sunrise each day with Da above a certain threshold (H). Both models satisfactorily predicted the variation in gl in dependent as well as in independent data, and the gl response functions used were supported by the experiments in controlled environments. The DH-model was more successful in predicting gl than the D-model by accounting for the observation that gl was lower at higher H under similar weather conditions. There was a considerable variation in maximum gl during the season, as well as between the two sites. On relatively warm and dry days xt rapidly declined during the morning and then stabilized around a constant value until the late afternoon, with the stomatal regulation effectively preventing xt from decreasing below this value. We suggest that these models could be used to simulate the gl in juvenile birch if maximum gl is locally estimated and if the response functions are not extrapolated beyond the climate range for this study. 相似文献
196.
Landegren U Schallmeiner E Nilsson M Fredriksson S Banér J Gullberg M Jarvius J Gustafsdottir S Dahl F Söderberg O Ericsson O Stenberg J 《Journal of molecular recognition : JMR》2004,17(3):194-197
Procedures and reagents are needed to specifically detect all the macromolecules that are being identified in the course of genome projects. We discuss how this challenge may be met using a set of ligation-based reagents termed padlock probes and proximity ligation probes. These probes include elements with affinity for specific nucleic acid and protein molecules, respectively, along with unique identifier DNA sequence elements that encode the identity of the recognized target molecules. The information content of DNA strands that form in the detection reactions are recorded after amplification, allowing the recognized target molecules to be identified. The procedures permit highly specific solution-phase or localized analyses of large sets of target molecules as required in future molecular analyses. 相似文献
197.
van Niel EW Palmfeldt J Martin R Paese M Hahn-Hägerdal B 《Applied and environmental microbiology》2004,70(3):1843-1846
Lactococcal lactate dehydrogenases (LDHs) are coregulated at the substrate level by at least two mechanisms: the fructose-1,6-biphosphate/phosphate ratio and the NADH/NAD ratio. Among the Lactococcus lactis species, there are strains that are predominantly regulated by the first mechanism (e.g., strain 65.1) or by the second mechanism (e.g., strain NCDO 2118). A more complete model of the kinetics of the regulation of lactococcal LDH is discussed. 相似文献
198.
Flensburg J Haid D Blomberg J Bielawski J Ivansson D 《Journal of biochemical and biophysical methods》2004,60(3):391-334
A new matrix-assisted laser desorption/ionization time of flight mass spectrometer (MALDI-ToF MS), developed specifically for the identification and characterization of proteins and peptides in proteomic investigations, is described. The mass spectrometer which can be integrated with the 2-D gel electrophoresis workflow is a bench-top instrument, enabling rapid, reliable and unattended protein identification in low-, as well as high-throughput proteomics applications. To obtain precise information on peptide sequences, the instrument utilizes a timed ion gate and a unique quadratic field reflectron (Z2 technology), allowing single-run, post-source decay (PSD) of selected peptides. In this study, the performance of the instrument in reflectron, PSD and linear mode, respectively, was investigated. The results showed that the limit of detection for a single peptide in reflectron mode was 125 amol with a signal to noise ratio exceeding 20. Average mass resolution for peptides larger than 2000 u was around 13,000 full width, half maximum (FWHM). The limit for protein identification during peptide mass fingerprinting (PMF) was 500 amol with a sequence coverage of 18%. Mass error during PMF analysis was less than 15 ppm for 17 out of 25 (68%) identified peptides. In PSD mode, a complete series of y-ions of a CAF-derivatized peptide could be obtained from 3.75 fmol of material. The average mass error of PSD-generated fragments was less than 0.14 u. Finally, in linear mode, intact proteins with molecular masses greater than 300,000 u were detected with mass errors below 0.2%. 相似文献
199.
Tropical biodiversity continues to erode unabated, which calls for ecologists to address the problem directly, placing less reliance on indirect interventions, such as community-based development schemes. Ecologists must become more assertive in providing scientifically formulated and adaptively managed interventions, involving biodiversity payments, to serve local, regional and global interests in tropical nature. Priorities for tropical ecologists thus include the identification of key thresholds to ecological resilience, and the formulation of clear monitoring protocols and management strategies for implementation by local resource managers. A particular challenge is to demonstrate how nature reserves contribute to the adaptive capacity of regional land-use matrices and, hence, to the provision of sustainable benefits at multiple spatial and temporal scales. 相似文献
200.
Positron emission tomography (PET) has proved to be a highly successful technique in the qualitative and quantitative exploration of the human brain's neurotransmitter-receptor systems. In recent years, the number of PET radioligands, targeted to different neuroreceptor systems of the human brain, has increased considerably. This development paves the way for a simultaneous analysis of different receptor systems and subsystems in the same individual. The detailed exploration of the versatility of neuroreceptor systems requires novel technical approaches, capable of operating on huge parametric image datasets. An initial step of such explorative data processing and analysis should be the development of novel exploratory data-mining tools to gain insight into the "structure" of complex multi-individual, multi-receptor data sets. For practical reasons, a possible and feasible starting point of multi-receptor research can be the analysis of the pre- and post-synaptic binding sites of the same neurotransmitter. In the present study, we propose an unsupervised, unbiased data-mining tool for this task and demonstrate its usefulness by using quantitative receptor maps, obtained with positron emission tomography, from five healthy subjects on (pre-synaptic) serotonin transporters (5-HTT or SERT) and (post-synaptic) 5-HT(1A) receptors. Major components of the proposed technique include the projection of the input receptor maps to a feature space, the quasi-clustering and classification of projected data (neighbourhood formation), trans-individual analysis of neighbourhood properties (trajectory analysis), and the back-projection of the results of trajectory analysis to normal space (creation of multi-receptor maps). The resulting multi-receptor maps suggest that complex relationships and tendencies in the relationship between pre- and post-synaptic transporter-receptor systems can be revealed and classified by using this method. As an example, we demonstrate the regional correlation of the serotonin transporter-receptor systems. These parameter-specific multi-receptor maps can usefully guide the researchers in their endeavour to formulate models of multi-receptor interactions and changes in the human brain. 相似文献