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  • 1
    Electronic Resource
    Electronic Resource
    17β-Estradiol-dependent regulation of chaperone expression and telomerase activity in the marine sponge Geodia cydonium (1999)
    Springer
    Marine biology 133 (1999), S. 1-10 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is known that species belonging to the lowest metazoan phylum, the Porifera (sponges), do not develop tumors. Sponge cells share with tumor cells of higher animals at least one characteristic; they contain high levels of telomerase activity, suggesting that they possess a high proliferation capacity. This assumption, however, has not been substantiated experimentally. In addition, sponges show a specific bauplan, leading us to postulate that they undergo apoptosis to replace a given set of cells at a given time. In the present study, 17β-estradiol (βE2) was used as a defined agent to assess its effect on both the telomerase activity and the process of apoptosis in the marine sponge Geodia cydonium (Jameson). It was found that βE2 (100 to 500 ng ml−1) caused increased expression (i) of the heat-shock protein HSP70 (Mr=70 000), a cytoplasmic chaperone; and (ii) of the nuclear chaperone thioredoxin (TRX), a protein involved in the control of cancer cell growth. For this purpose the gene of G. cydonium encoding TRX was cloned, and the cDNA was applied for the determination of the expression. Verapamil, an inhibitor of both the mammalian multidrug resistance pump and the invertebrate multixenobiotic resistance pump, was used in co-incubation experiments with βE2 to increase the uptake of βE2. The experiments revealed that verapamil augmented the βE2 effect on the expression of the two chaperones, HSP70 and TRX. In addition, the tissue of G. cydonium underwent apoptosis, and the cells lost their telomerase activity. In parallel with the induction of the apoptotic process, the number of DNA strand breaks increased. It is concluded that βE2 displays its effect via the production of reactive oxygen species (ROS). At physiological concentrations ROS cause the expression of HSP70 and TRX, while at higher ROS levels, generated during the co-incubation period of βE2 with verapamil, the cells undergo apoptosis and lose telomerase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050436
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of Hsp70 by the Herbicide Oxyfluorfen (Goal) in the Egyptian Nile Fish, Oreochromis niloticus (1999)
    Springer
    Archives of environmental contamination and toxicology 37 (1999), S. 78-84 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. This paper deals with the expression of the biomarker hsp70 in the liver and kidney of the freshwater fish Oreochromis niloticus following exposure to the herbicide oxyfluorfen (Goal). Fishes were exposed to three concentrations, the 96-h LC50 (3 mg/L), the 96-h ½LC50 (1.5 mg/L), and the 96-h ¼LC50 (0.75 mg/L) of oxyfluorfen for 6, 15, and 24 days, respectively, and samples were taken at three different time periods for each concentration. The livers responded to the herbicide by an induction of the expression of both the constitutive (hsp75; Mr 75 kDa) and the inducible (hsp73; Mr 73 kDa) hsp70 proteins. In kidney, the herbicide induced a time-dependent increase in the expression of the constitutive hsp70 (hsp75) as well, but the inducible hsp70 (hsp73) required much longer incubation periods to reach maximal levels (15 and 24 days). Our results suggest that expression of hsp70 in fish is a sensitive indicator of cellular responses to herbicide exposure in the aquatic environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900492
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  • 3
    Electronic Resource
    Electronic Resource
    Induction of DNA Strand Breaks and Expression of HSP70 and GRP78 Homolog by Cadmium in the Marine Sponge Suberites domuncula (1999)
    Springer
    Archives of environmental contamination and toxicology 36 (1999), S. 47-55 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The marine sponge Suberites domuncula was used as a bioindicator to study the effects of cadmium on the occurrence of DNA strand breakage and on the induction of the expression of the stress biomarkers, heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78) homolog. The cDNA encoding GRP78 homolog from S. domuncula was isolated and characterized. The GRP78 cDNA has a length of 2.1 kb and displays characteristic features of the HSP70 family; it encodes an aa sequence of Mr 72,000. Exposure of S. domuncula to 1 mg/L of cadmium chloride for 24 h caused a strong (16.6-fold) increase in cadmium content to 7.7 μg/g wet weight of sponge tissue; after an incubation period of 6 days, the accumulation was 20.4-fold. The increase in cadmium content was paralleled by a transient decrease in zinc content at days 1 and 3. Exposure of S. domuncula to cadmium chloride also resulted in a marked increase in the number of DNA single strand breaks, as assessed by a recently developed fast and sensitive microplate assay. The maximum increase in DNA damage was observed after an incubation of 12 h in the presence of 1 mg/L of cadmium chloride; after longer incubation, the number of damaged sites decreased, most likely due to DNA repair. Quantitative analysis of the expression of HSP70 (Mr 73 kDa) revealed that onset of maximal levels of HSP70 depends on the concentration of cadmium chloride in the ambient seawater. Maximal induction (8.9-fold increase compared to control) of HSP70 following exposure to 1 mg/L of cadmium chloride was found after 12 h, while longer incubation periods (3–6 days) were needed to reach maximum levels of HSP70 in the presence of lower concentrations of cadmium chloride (0.1 mg/L and 0.01 mg/L). Northern blot analysis revealed that the level of the 2.0 kb sponge GRP78 homolog mRNA transiently increased under cadmium stress; the maximum increase in the presence of 0.1 mg/L of cadmium chloride was observed at day 3. Our results suggest that sponges are useful indicator organisms to assess the genotoxic risks of cadmium pollution in marine environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900441
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    Paper (German National Licenses)
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