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Bergbaufolgegewässer
(2001)
Over the last decade the modeling and the storage of biological data has been a topic of wide interest for scientists dealing with biological and biomedical research. Currently most data is still stored in text files which leads to data redundancies and file chaos. In this paper we show how to use relational modeling techniques and relational database technology for modeling and storing biological sequence data, i.e. for data maintained in collections like EMBL or SWISS-PROT to better serve the needs for these application domains. For this reason we propose a two step approach. First, we model the structure (and therefore the meaning of the) data using an Entity-Relationship approach. The ER model leads to a clean design of a relational database schema for storing and retrieving the DNA and protein data extracted from various sources. Our approach provides the clean basis for building complex biological applications that are more amenable to changes and software ports than their file-base counterparts.
Variation in the competitive ability of plant species is suggested to determine their persistence and abundance in communities. In this study, we examine competition between grasses and woody plants, a phenomenon that occurs word-wide in savannas and along the margins between grasslands and forests. Specifically, we quantified the per- gram competitive effects of grasses and woody plants in native mixed-grass prairie by manipulating the natural vegetation. We separated the competitive effects of grasses, shrubs, and intact vegetation using selective herbicides to create four competition treatments: no neighbours (NN), no shrubs (NS), no grasses (NG), and all neighbours (AN). Competition treatments were applied to 2m x 2m experimental plots located in either prairie- or shrub- dominated habitats. Herbicides were applied starting one year prior to the study to create the four competition treatments. The effects of grasses and shrubs on resource availability (light, water, nitrogen) and the growth of two transplant species, Bouteloua gracilis, a perennial tussock grass, and Elaeagnus commutata, a common shrub, were measured over two growing seasons. Resource availability (i.e. light, soil moisture, soil available nitrogen) was two- to tenfold higher in no neighbour (NN) plots than in vegetated plots (NS, NG, AN). Both grasses and shrubs reduced resource levels to about the same extent. Light penetration declined linearly with increasing grass or shrub biomass, to a minimum of about 30% incident light at 500 g/m² neighbour shoot mass. Soil resources (i.e. water, nitrogen) did not decline with increasing neighbour shoot or root mass for either grasses or shrubs. Thus, for soil resources, the presence of neighbours was more important than their mass (i.e. abundance). Transplant growth did not decline with increasing neighbour biomass; the only exception to this pattern was a linear decline in Bouteloua growth with increasing neighbour shoot mass in plots containing only shrubs (NG). Competition was equally intense in prairie-dominated and shrub-dominated habitats for transplants of Bouteloua, but was less intense in shrub-dominated habitats for the shrub Elaeagnus. These results raise the interesting possibility that variation in the persistence and abundance of plants in communities is more strongly controlled by variation in competitive effects than by differences in competitive response ability.
Conclusions and outlook
(2001)
1. After observing that juvenile roach fed intensively on cyanobacteria and that cyanobacteria were densely colonized by heterotrophic bacteria, we tested whether the bacteria are used by underyearling roach and the extent to which they contribute to the energy requirements of the fish. 2. We radiolabeled attached bacteria in a natural cyanobacterial suspension, fed the fish with these particles, and estimated their assimilation by roach. Biomass of attached bacteria on cyanobacteria increased with the proportion of the cyanobacterium Microcystis in total cyanobacteria. Biomass-specific thymidine incorporation of attached bacteria was higher than that of free bacteria. 3. In feeding experiments, we detected assimilation of bacterial biomass into muscle tissue of underyearling roach. Fish consumed Microcystis to a lesser extent compared to Aphanizomenon but assimilation of attached bacteria was higher when roach fed on Microcystis due to the higher biomass of epibacteria on this cyanobacterium. However, biomass of attached bacteria was too low to be an important food source for underyearling roach. 4. We conclude that assimilation of epibacteria from cyanobacteria cannot explain the success of roach in eutrophic lakes.
Cytochrom P450-Elektrochemie
(2001)
Determination of phenolic compounds using recombinant tyrosinanse from Streptomyces antibioticus
(2001)
Dopamine-induced epithelial K+ and Na+ movements in the salivary ducts of Periplaneta americana
(2001)
Dendritic cells (DCs) are the most potent antigen-presenting cells of the immune system and are currently being investigated in clinical applications as cancer vaccines. An efficient cryopreservation method would greatly contribute to their use in clinical trials. We have established a method for freezing of DCs derived from peripheral blood mononuclear cells using the plasma expander Gelifundol. This enabled us to reduce the concentration of the toxic DMSO to 5%. The method could be performed without the addition of fetal calf serum or any other serum. After freezing, the viability of the DCs was 90%. The cells exhibited all the phenotypic characteristics (CD11c+, HLA-DR+, CD80+, CD83+, CD86+) of DCs, as tested by flow cytometry. Cells transfected with cDNA for the tumour antigen mucin expressed this protein on their surfaces in the same manner as before freezing. The stimulating capacity of a mixed lymphocyte culture was also preserved. These findings offer an efficient method for the cryopreservation of DCs for use in clinical trials.
Enthalpic barriers to the hydrophobic binding of oligosaccharides to phage P22 tailspike protein
(2001)
Tumor antigen-specific T cell clones represent a useful tool in tumor immunology; however, their long-term culture is limited. To generate an immortalized cytotoxic T cell clone against the human tumor antigen mucin, we exposed a previously generated T cell culture to Herpesvirus saimiri. We obtained an immortalized human CD4+ T cell clone, termed SITAM. Clonality of these cells was shown by analysis of the alpha/beta-T cell receptor (TCR) repertoire. Cytolytic activity was demonstrated against several mucin-expressing tumor cell lines and could not be detected against non-mucin-expressing cells. SITAM cells maintained their features stably for 2 years. Furthermore, growth of the tumor cell line Capan-2 in NOD/SCID mice was inhibited when SITAM cells were coinjected subcutaneously with tumor cells. SITAM cells provide an unlimited source of clonal T cells for analysis of tumor recognition and may be of help in TCR-targeted immunotherapy.
In order to broaden our understanding of the eukaryotic CO2- concentrating mechanism the occurrence and localization of a thylakoid-asssocaate carbonic anhydrase (EC 4.2.1.1) were studied in the green algae Tetraedron on minimum and Chlamydomonas noctigama. Both algae induce a CO2-concentrating mechanism when grown under limiting CO2 conditions. Using mass- spectrometric measurements of O-18 exchange from doubly labelled CO2, the presence of a thylakoid-associated carbonic anhydrase was confirmed for both species. From purified thylakoid membranes, photosystem I (PSI), photosystem II (PSII) and the light-harvesting complex of the photosynthetic apparatus were isolated by mild detergent gel. The protein fractions were identified by 77 K fluorescence spectroscopy and immunological studies. A polypeptide was found to immunoreact with an antibody raised against thylakoid carbonic anhydrase (CAH3) from Chlamydomonas reinhardtii. It was found that this polypeptide was mainly associated with PSII, although a certain proportion was also connected to light harvesting complex II. This was confirmed by activity measurements of carbonic anhydrase in isolated bands extracted from the mild detergent gel. The thylakoid carbonic anhydrase isolated from T. minimum had an isoelectric point between 5.4 and 4.8. Together the results are consistent with the hypothesis that thylakoid carbonic anhydrase resides within the lumen where it is associated with the PSII complex.
Industrieanthropologie
(2001)