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1.
Genetically modified plants are widely grown predominantly in North America and to a lesser extent in Australia, Argentina and China but their regions of production are expected to spread soon beyond these limited areas also reaching Europe where great controversy over the application of gene technology in agriculture persists. Currently, several cultivars of eight major crop plants are commercially available including canola, corn, cotton, potato, soybean, sugar beet, tobacco and tomato, but many more plants with new and combined multiple traits are close to registration. While currently agronomic traits (herbicide resistance, insect resistance) dominate, traits conferring “quality” traits (altered oil compositions, protein and starch contents) will begin to dominate within the next years. However, economically the most promising future lies in the development and marketing of crop plants expressing pharmaceutical or “nutraceuticals” (functional foods), and plants that express a number of different genes. From this it is clear that future agricultural and, ultimately, also natural ecosystems will be challenged by the large-scale introduction of entirely novel genes and gene products in new combinations at high frequencies all of which will have unknown impacts on their associated complex of non-target organisms, i.e. all organisms that are not targeted by the insecticidal protein. In times of severe global decline of biodiversity, pro-active precaution is necessary and careful consideration of the likely expected effects of transgenic plants on biodiversity of plants and insects is mandatory.In this paper possible implications of non-target effects for insect and plant biodiversity are discussed and a case example of such non-target effects is presented. In a multiple year research project, tritrophic and bitrophic effects of transgenic corn, expressing the gene from Bacillus thuringiensis (Bt-corn) that codes for the high expression of an insecticidal toxin (Cry1Ab), on the natural enemy species, Chrysoperla carnea (the green lacewing), was investigated. In these laboratory trials, we found prey-mediated effects of transgenic Bt-corn causing significantly higher mortality of C. carnea larvae. In further laboratory trials, we confirmed that the route of exposure (fed directly or via a herbivorous prey) and the origin of the Bt (from transgenic plants or incorporated into artificial diet) strongly influenced the degree of mortality. In choice feeding trials where C. carnea could choose between Spodoptera littoralis fed transgenic Bt-corn and S. littoralis fed non-transgenic corn, larger instars showed a significant preference for S. littoralis fed non-transgenic corn while this was not the case when the choice was between Bt- and isogenic corn fed aphids. Field implications of these findings could be multifold but will be difficult to assess because they interfere in very intricate ways with complex ecosystem processes that we still know only very little about. The future challenge in pest management will be to explore how transgenic plants can be incorporated as safe and effective components of IPM systems and what gene technology can contribute to the needs of a modern sustainable agriculture that avoids or reduces adverse impacts on biodiversity? For mainly economically motivated resistance management purposes, constitutive high expression of Bt-toxins in transgenic plants is promoted seeking to kill almost 100% of all susceptible (and if possible heterozygote resistant) target pest insects. However, for pest management this is usually not necessary. Control at or below an established economic injury level is sufficient for most pests and cropping systems. It is proposed that partially or moderately resistant plants expressing quantitative rather than single gene traits and affecting the target pest sub-lethally may provide a more meaningful contribution of agricultural biotechnology to modern sustainable agriculture. Some examples of such plants produced through conventional breeding are presented. Non-target effects may be less severe allowing for better incorporation of these plants into IPM or biological control programs using multiple control strategies, thereby, also reducing selection pressure for pest resistance development. 相似文献
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Angelika Barnekow Werner A. Müller 《Differentiation; research in biological diversity》1987,33(3):29-33
Abstract. The metamorphosis of planula larvae of the hydroid, Hydractinia , into primary polyps can be artificially triggered by Li, Rb, and Cs ions, by tumor-promoting phorbol esters [14], and by diacylglycerols. Metamorphosis implies the transition of morphogenetically quiescent cells to a state of terminal differentiation or transdifferentiation. Among the events which occur during the first 2.5 h after induction is an increase in the level of activity of a protein kinase that is precipitated by antisera against Rous sarcoma virus-derived pp60src and that phosphorylates tyrosine in the precipitated IgG. Immunoprecipitation using a preimmune serum did not yield any corresponding kinase activity. The antigenic relationship between the Hydractinia protein and vertebrate pp60c-src "' was demonstrated by applying an immune competition assay. 相似文献
4.
Peter J. Gebicke-Haerter Andr s Seregi Angelika Schobert Georg Hertting 《Neurochemistry international》1988,13(4):475-480
The role of protein kinase C (PKC) and calcium in the stimulation of prostaglandin D2 (PGD2) synthesis was investigated in primary rat astroglial cultures using the phorbol esters phorbol 12-myristate, 13-acetate (PMA), phorbol 12,13-dibutyrate (PDB) and the calcium ionophore A23187. Both phorbol esters and the ionophore were able to stimulate PGD2 synthesis in a concentration dependent manner. The inactive stereoisomers of PMA and PDB had no significant effect. Combinations of subthreshold concentrations of phorbol esters (10 nM PMA or 10 nM PBD) potentiated PG formation induced by 100 nM A23187. An even more pronounced effect was observed when phorbol ester concentrations were increased to 100nM. The contribution of extra- and intracellular calcium in phorbol ester or A23187 stimulated PGD2 synthesis was evaluated by carrying out experiments with calcium-free media plus EGTA or with the intracellular calcium-chelating agent TMB-8. Ionophore stimulated PGD2 release was shut down to basal values upon removal of extracellular calcium, whereas phorbol ester stimulated PGD2 formation persisted at a reduced level. It was unabated also upon further addition of EGTA. In the presence of TMB-8, however, phorbol ester stimulated PGD2 synthesis was completely suppressed. These data strongly suggest that PKC has an additional effect on the activation of phospholipase A2 and subsequent prostanoid synthesis, which is independent from extracellular calcium and, thus, support the concept of more than one metabolic pathway in astrocytes that synergistically regulate phospholipase A2 activity. 相似文献
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Vera Eickel Barbara Kahl Beatrice Reinisch Angelika Dübbers Peter Küster Claudia Brandt Barbara Spellerberg 《PloS one》2009,4(2)
Streptococcus agalactiae is a well-known pathogen for neonates and immunocompromized adults. Beyond the neonatal period, S. agalactiae is rarely found in the respiratory tract. During 2002–2008 we noticed S. agalactiae in respiratory secretions of 30/185 (16%) of cystic fibrosis (CF) patients. The median age of these patients was 3–6 years older than the median age CF patients not harboring S. agalactiae. To analyze, if the S. agalactiae isolates from CF patients were clonal, further characterization of the strains was achieved by capsular serotyping, surface protein determination and multilocus sequence typing (MLST). We found a variety of sequence types (ST) among the isolates, which did not substantially differ from the MLST patterns of colonizing strains from Germany. However serotype III, which is often seen in colonizing strains and invasive infections was rare among CF patients. The emergence of S. agalactiae in the respiratory tract of CF patients may represent the adaptation to a novel host environment, supported by the altered surfactant composition in older CF patients. 相似文献
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Angelika Brandt 《Polar Biology》1993,13(8):565-576
Composition, abundance, and diversity of Crustacea Peracarida were investigated on a transect across the Kolbeinsey Ridge, north of Iceland in summer 1992 during the M21/5 expedition with RV Meteor. This ridge is influenced by both the cold East Greenland Current as well as the warmer East Iceland Current, mixing with warmer Atlantic water. Sampling has been performed using an epibenthic sledge modified after Rothlishberg & Pearcy (1977). Being one of the most important components of the macrobenthic epi- and suprafauna, composition, abundance, and diversity of peracarids was significantly different on western and eastern sides of the slope. Isopoda and Amphipoda were most frequent at all stations, followed by Cumacea and Tanaidacea. Mysidacea have only been sampled on the eastern slope. Abundance and diversity were highest on the two eastern stations in depths of 830–940 meters, values decreased on the deepest eastern station in 1100 meter depth and were also low on both western stations in 830 and 860 meters depth. These differences are probably due to sediment composition and to quality and quantity of organic carbon reaching the seafloor, rather than to differences in salinity or in hydrographic regimes. The high abundance of peracarid crustaceans, especially of epibenthic species, capable of burrowing within the first centimeters of sediment, indicate their high potential of bioturbation and also their importance for benthic carbon cycling. 相似文献
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Hubert Pausch Hermann Schwarzenbacher Johann Burgstaller Krzysztof Flisikowski Christine Wurmser Sandra Jansen Simone Jung Angelika Schnieke Thomas Wittek Ruedi Fries 《BMC genomics》2015,16(1)