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Michael J. Lydy - One of the best experts on this subject based on the ideXlab platform.
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effect of sediment associated pyrethroids fipronil and metabolites on Chironomus Tentans growth rate body mass condition index immobilization and survival
Environmental Toxicology and Chemistry, 2008Co-Authors: Amanda A Brennan, Jonathan D Maul, Amanda D Harwood, Michael J. LydyAbstract:Pyrethroids and fipronil insecticides partition to sediment and organic matter in aquatic systems and may pose a risk to organisms that use these matrices. It has been suggested that bioavailability of sediment-sorbed pesticides is reduced, but data on toxicity of sediment-associated pesticides for pyrethroids and fipronil are limited. In the current study, 10-d sediment exposures were conducted with larval Chironomus Tentans for bifenthrin, lambda-cyhalothrin, permethrin, fipronil, fipronil-sulfide, and fipronil- sulfone, the last two being common fipronil metabolites. Sublethal endpoints included immobilization, instantaneous growth rate (IGR), body condition index, and growth estimated by ash-free dry mass (AFDM). Pyrethroid lethal concentrations to 50% of the population (LC50s) were 6.2, 2.8, and 24.5 g/g of organic carbon (OC) for bifenthrin, lambda-cyhalothrin, and permethrin, respectively; with the former two lower than previously published estimates. Fipronil, fipronil-sulfide, and fipronil-sulfone LC50 values were 0.13, 0.16, and 0.12 g/g of OC, respectively. Ratios of LC50s to sublethal endpoints (immobilization, IGR, and AFDM) ranged from 0.90 to 9.03. The effects on growth observed in the present study are important because of the unique dipteran life cycle involving pupation and emergence events. Growth inhibition would likely lead to ecological impacts similar to mortality (no emergence and thus not reproductively viable) but at concentrations up to 4.3 times lower than the LC50 for some compounds. In addition, C. Tentans was highly sensitive to fipronil and metabolites, suggesting that dipterans may be important for estimating risk and understanding effects of phenylpyrazole-class insecticides on benthic macroinvertebrate communities. Keywords—Chironomus Tentans Fipronil Pyrethroids Sediment toxicity Sublethal responses
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examining the joint toxicity of chlorpyrifos and atrazine in the aquatic species lepomis macrochirus pimephales promelas and Chironomus Tentans
Environmental Pollution, 2008Co-Authors: Tyler W Mehler, Lance J. Schuler, Michael J. LydyAbstract:The joint toxicity of chlorpyrifos and atrazine was compared to that of chlorpyrifos alone to discern any greater than additive response using both acute toxicity testing and whole-body residue analysis. In addition, acetylcholinesterase (AChE) inhibition and biotransformation were investigated to evaluate the toxic mode of action of chlorpyrifos in the presence of atrazine. The joint toxicity of atrazine and chlorpyrifos exhibited no significant difference in Lepomis macrochirus compared to chlorpyrifos alone; while studies performed with Pimephales promelas and Chironomus Tentans, did show significant differences. AChE activity and biotransformation showed no significant differences between the joint toxicity of atrazine and chlorpyrifos and that of chlorpyrifos alone. From the data collected, the combination of atrazine and chlorpyrifos pose little additional risk than that of chlorpyrifos alone to the tested fish species.
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Effect of sediment‐associated pyrethroids, fipronil, and metabolites on Chironomus Tentans growth rate, body mass, condition index, immobilization, and survival
Environmental toxicology and chemistry, 2008Co-Authors: Jonathan D Maul, Amanda A Brennan, Amanda D Harwood, Michael J. LydyAbstract:Pyrethroids and fipronil insecticides partition to sediment and organic matter in aquatic systems and may pose a risk to organisms that use these matrices. It has been suggested that bioavailability of sediment-sorbed pesticides is reduced, but data on toxicity of sediment-associated pesticides for pyrethroids and fipronil are limited. In the current study, 10-d sediment exposures were conducted with larval Chironomus Tentans for bifenthrin, lambda-cyhalothrin, permethrin, fipronil, fipronil-sulfide, and fipronil- sulfone, the last two being common fipronil metabolites. Sublethal endpoints included immobilization, instantaneous growth rate (IGR), body condition index, and growth estimated by ash-free dry mass (AFDM). Pyrethroid lethal concentrations to 50% of the population (LC50s) were 6.2, 2.8, and 24.5 g/g of organic carbon (OC) for bifenthrin, lambda-cyhalothrin, and permethrin, respectively; with the former two lower than previously published estimates. Fipronil, fipronil-sulfide, and fipronil-sulfone LC50 values were 0.13, 0.16, and 0.12 g/g of OC, respectively. Ratios of LC50s to sublethal endpoints (immobilization, IGR, and AFDM) ranged from 0.90 to 9.03. The effects on growth observed in the present study are important because of the unique dipteran life cycle involving pupation and emergence events. Growth inhibition would likely lead to ecological impacts similar to mortality (no emergence and thus not reproductively viable) but at concentrations up to 4.3 times lower than the LC50 for some compounds. In addition, C. Tentans was highly sensitive to fipronil and metabolites, suggesting that dipterans may be important for estimating risk and understanding effects of phenylpyrazole-class insecticides on benthic macroinvertebrate communities. Keywords—Chironomus Tentans Fipronil Pyrethroids Sediment toxicity Sublethal responses
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Response spectrum of pentachlorobenzene and fluoranthene for Chironomus Tentans and Hyalella azteca.
Environmental toxicology and chemistry, 2007Co-Authors: Lance J. Schuler, Peter F. Landrum, Michael J. LydyAbstract:The whole-body residues of pentachlorobenzene (PCBz) and fluoranthene (FLU) in Hyalella azteca and Chironomus Tentans were determined for a variety of chronic sublethal effects. The endpoints evaluated for H. azteca included 28-d growth and survival and 42-d growth, survival, and reproduction. Adverse effects to C. Tentans also were determined at multiple endpoints including 10-d growth, cumulative pupation and emergence, and reproduction. The lowest-observed-effect residue (LOER) based on whole-body residues associated with growth was consistent between compounds and species tested with concentrations ranging from 0.17 to 0.33 μmol/g. For H. azteca, the most sensitive endpoints were growth at 0.23 μmol/g and reproduction at 0.11 μmol/g for PCBz and FLU, respectively. For C. Tentans, the most sensitive endpoints were emergence, development and reproduction at 0.02 μmol/g, and development and reproduction at 0.15 μmol/g for PCBz and FLU, respectively. Compared to residues associated with acute lethality, the most sensitive sublethal endpoints were approximately 4 and 60 times lower for PCBz and FLU, respectively. The relative consistency of the sublethal endpoints suggests that body residues can be a valuable tool to evaluate bioaccumulation data as part of a risk assessment to predict adverse effects to biota.
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toxicity assessment of pesticide mixtures typical of the sacramento san joaquin delta using Chironomus Tentans
Archives of Environmental Contamination and Toxicology, 2004Co-Authors: Michael J. Lydy, K R AustinAbstract:This study examined the effects of nine commonly detected pesticides in the Sacramento–San Joaquin Delta on the aquatic midge Chironomus Tentans. Pesticides were chosen from a variety of chemical classes including organophosphate (OP) insecticides as well as triazine, triazinone, and substituted urea herbicides. Both single toxicant and binary mixture bioassays were performed. In addition, midges were pre-exposed to DDE at environmentally relevant concentrations and then challenged by exposing them to chlorpyrifos or diazinon in single-toxicant acute bioassays. Results indicate that most of the binary mixtures elicited additive responses in C. Tentans, whereas OP insecticides in combination with various herbicides caused greater-than-additive responses. Pre-exposures with DDE did not have a significant impact on subsequent OP challenges at DDE concentrations of 0.2, 2, and 20 μg/kg. This study represents an important first step in understanding the interactions among various pesticides commonly detected throughout the Delta.
Lars Wieslander - One of the best experts on this subject based on the ideXlab platform.
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Processing of pre-mRNA in polytene nuclei of Chironomus Tentans salivary gland cells.
Experimental cell research, 1996Co-Authors: Lars Wieslander, Kerstin Bernholm, Göran Baurén, Wei-qin Jiang, Ingela WetterbergAbstract:Abstract Salivary gland polytene cells in the dipteran Chironomus Tentans provide exceptional experimental possibilities to analyze processing of specific pre-mRNAs in intact eukaryotic cell nuclei. Here we give a brief account of how these experimental advantages can be exploited to analyze the splicing process in vivo. In multi-intron pre-mRNAs, spliceosomes assemble and splicing is initiated cotranscriptionally for all introns. Intron excision may, however, occur mainly co- transcriptionally or mainly posttranscriptionally depending on the position of each intron in relation to the remaining transcription time and intron-specific efficiencies of excision. As measured for the U2 snRNP and an SR protein, 10–15% of the spliceosomal components are bound to pre-mRNA at active gene loci at a given moment, while the majority of the spliceosomal components are present in the nucleoplasm. A continuous redistribution of the spliceosomal components takes place in the nucleus as a result of a close coupling between transcription and spliceosomal assembly.
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Structure of the smallest salivary-gland secretory protein gene in Chironomus Tentans
Journal of molecular evolution, 1994Co-Authors: Joakim Galli, Lars WieslanderAbstract:The salivary gland secretion in the dipteran Chironomus Tentans is composed of approximately 15 different secretory proteins. The most well known of the corresponding genes are the four closely related Balbiani ring (BR) genes, in which the main part of each approximately 40-kb gene is composed of tandemly arranged repetitive units. Six of the seven additional secretory protein genes described share structural similarities with the BR genes and are members of the same BR multigene family. Here we report the identification of a new secretory protein gene, the spl2 gene, encoding the smallest component of the C. Tentans salivary gland secretion. The gene has a corresponding mRNA length of approximately 0.7 kb and codes for a protein with a calculated molecular weight of 7,619 Da. The sp12 gene was characterized in seven Chironomus species. Based on a comparison of the orthologous gene sequences, we conclude that the sp12 gene has a repetitive structure consisting of diverged 21-by-long repeats. The repeat structure and the codon composition are similar to the so-called SR regions of the BR genes and the sp 12 gene may represent a diverged member of the BR multigene family.
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Sequence organization of the Balbiani ring 2.1 gene in Chironomus Tentans
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: Lars Wieslander, Gabrielle PaulssonAbstract:Abstract Balbiani rings are giant chromosomal puffs, containing related genes that provide unique possibilities for in vivo analysis of gene expression at the chromatin and ribonucleoprotein levels. Here, the 5' end of the Balbiani ring 2.1 gene in the dipteran Chironomus Tentans has been isolated and the sequence organization of the entire Balbiani ring gene is presented. The gene contains five exons, one being extremely small, only 6 base pairs, and one being extremely large, approximately 30 kilobase pairs. Three introns are located at the 5' end and a fourth one is located at the 3' end. The central 30-kilobase-pair exon is entirely built from tandemly organized repeats. All repeats are virtually identical except for a few variant repeats at both ends of the repeat array. The number of repeats may vary between alleles and the length of the gene therefore changes between 30 and 35 kilobase pairs.
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Conserved and variable repeat structures in the Balbiani ring gene family in Chironomus Tentans.
Journal of molecular evolution, 1992Co-Authors: Gabrielle Paulsson, Kerstin Bernholm, Lars WieslanderAbstract:The four Balbiani ring (BR) genes, BR1, BR2.1, BR2.2, and BR6 in the midge Chironomus Tentans constitute a gene family encoding secretory proteins with molecular weights of approximately 106 daltons. The major part of each gene is known to consist of tandemly organized composite repeat units resulting in a hierarchic repeat arrangement.
Nairanjana Dasgupta - One of the best experts on this subject based on the ideXlab platform.
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Morphologic and growth responses in Chironomus Tentans to arsenic exposure.
Archives of environmental contamination and toxicology, 2006Co-Authors: Edward A. Martinez, Barry C. Moore, John Schaumloffel, L. Wold, Nairanjana DasguptaAbstract:Laboratory bioassays consisting of sediments spiked with three concentrations (30, 130, and 260 μg g−1 As dry wt) of arsenic (As+3) were used to assess morphologic responses and growth in Chironomus Tentans larvae. Chironomid larvae were raised in contaminated sediments from egg stage to emergence, and mouthpart abnormalities, larval length, and larval head width were used as end points to determine differences between metal-spiked and control specimens. C. Tentans exhibited significantly higher mouthpart deformity proportions, smaller body sizes, smaller head widths, and slower development than control larvae. Our results demonstrate a dose–response relationship between As and mentum deformities in C. Tentans. However, the proportion of deformed larvae did not increase with time in the treatment tanks. Results demonstrate that As induces mouthpart abnormalities at various concentrations. This research provides more support for the use of chironomid abnormalities as a tool for the assessment of heavy-metal pollution in aquatic systems.
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Morphological abnormalities in Chironomus Tentans exposed to cadmium-and copper-spiked sediments.
Ecotoxicology and environmental safety, 2003Co-Authors: Edward A. Martinez, Barry C. Moore, John Schaumloffel, Nairanjana DasguptaAbstract:Abstract The induction of mouthpart deformities and the developmental response with exposure to sediments spiked with three concentrations (9, 39, and 61 μg g −1 Cd dry wt.) of cadmium (Cd) and three concentrations (30, 125, and 215 μg g −1 Cu dry wt.) of copper (Cu) were investigated. Mouthpart deformity proportions in Chironomus Tentans larvae were compared between metal-spiked and control populations and between parent and offspring (F1) populations. Cd- and Cu-treated sediments induced deformities (low Cd=13%, medium Cd=7%, high Cd=4%, low Cu=6%, medium Cu=9%, high Cu=6%) at significantly higher proportions than control (3%) sediments. No negative developmental response was determined. Larval sizes in metal-treated aquaria and control aquaria were not significantly different. F1 larvae from parents reared in medium and high Cu had significantly lower deformity rates than their parents. Our research adds to the growing evidence implicating heavy metals in general, and Cd and Cu specifically, as teratogenic agents.
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induction of morphological deformities in Chironomus Tentans exposed to zinc and lead spiked sediments
Environmental Toxicology and Chemistry, 2001Co-Authors: Edward A. Martinez, Barry C. Moore, John Schaumloffel, Nairanjana DasguptaAbstract:Laboratory experiments were used to assess morphological responses of Chironomus Tentans larvae exposed to three levels of zinc and lead. Chironomus Tentans egg masses were placed into triplicate control and metal-spiked aquaria containing the measured concentrations 1,442, 3,383, and 5,562 microg/g Pb dry weight and 1,723, 3,743, and 5,252 microg/g Zn dry weight. Larvae were collected at 10-d intervals after egg masses were placed in aquaria until final emergence. Larvae were screened for mouthpart deformities and metal body burdens. Deformities increased with time of exposure in both Zn and Pb tanks. Deformity rates between the three Zn concentrations differed statistically, with low and medium Zn levels containing the highest overall deformity rates of 12%. Deformity rates for larvae held in the Pb aquaria were found to differ significantly. Larvae in the low-Pb tanks had a deformity rate of 9%. Larvae and water from both the Zn and Pb aquaria had increasing metal concentrations with increasing sediment metal concentration. Results demonstrate that Zn and Pb each induce chironomid mouthpart deformities at various concentrations. However, a clear dose-related response was not demonstrated. Our research provides more support for the potential use of chironomid deformities as a tool for the assessment of heavy metal pollution in aquatic systems.
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Induction of morphological deformities in Chironomus Tentans exposed to zinc‐ and lead‐spiked sediments
Environmental toxicology and chemistry, 2001Co-Authors: Edward A. Martinez, Barry C. Moore, John Schaumloffel, Nairanjana DasguptaAbstract:Laboratory experiments were used to assess morphological responses of Chironomus Tentans larvae exposed to three levels of zinc and lead. Chironomus Tentans egg masses were placed into triplicate control and metal-spiked aquaria containing the measured concentrations 1,442, 3,383, and 5,562 microg/g Pb dry weight and 1,723, 3,743, and 5,252 microg/g Zn dry weight. Larvae were collected at 10-d intervals after egg masses were placed in aquaria until final emergence. Larvae were screened for mouthpart deformities and metal body burdens. Deformities increased with time of exposure in both Zn and Pb tanks. Deformity rates between the three Zn concentrations differed statistically, with low and medium Zn levels containing the highest overall deformity rates of 12%. Deformity rates for larvae held in the Pb aquaria were found to differ significantly. Larvae in the low-Pb tanks had a deformity rate of 9%. Larvae and water from both the Zn and Pb aquaria had increasing metal concentrations with increasing sediment metal concentration. Results demonstrate that Zn and Pb each induce chironomid mouthpart deformities at various concentrations. However, a clear dose-related response was not demonstrated. Our research provides more support for the potential use of chironomid deformities as a tool for the assessment of heavy metal pollution in aquatic systems.
Daniel J. Chappie - One of the best experts on this subject based on the ideXlab platform.
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optimization of in situ bioassays with hyalella azteca and Chironomus Tentans
Environmental Toxicology and Chemistry, 1997Co-Authors: Daniel J. Chappie, Allen G BurtonAbstract:Uncertainty is always associated with extrapolations of laboratory toxicity test responsesto in situ conditions. Exposing toxicity test organisms in situ reduces uncertainty by removing sampling related artifacts and better simulating natural exposures. The amphipod Hyalella azteca and the midge Chironomus Tentans, were enclosed in plastic containers with 149- or 74-mm mesh openings. These chambers were anchored to stream substrates allowing continual water exchange and contact with sediments. Hyallela azteca survival was greater than 80% after 4 weeks of exposure. In situ testing with H. azteca in cold water (<15°C) resulted in survival consistently below 60%, possibly due to limited acclimation periods. Handling stress during laboratory to field transport reduced C. Tentans survival. High survival was not consistently achieved until a protective ground paper towel substrate was used. A smaller mesh size (74 mm) on the chambers reduced the occurrence of indigenous organisms inside the chambers, making C. Tentans identification unmistakable. In situ testing with C. Tentans using refined methods resulted in greater than 80% survival after 2 weeks of exposure. In situ exposures of these two benthic invertebrates can effectively evaluate short- to long-term conditions of water and sediment quality.
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Optimization of in situ bioassays with Hyalella azteca and Chironomus Tentans
Environmental Toxicology and Chemistry, 1997Co-Authors: Daniel J. Chappie, G. Allen BurtonAbstract:Uncertainty is always associated with extrapolations of laboratory toxicity test responsesto in situ conditions. Exposing toxicity test organisms in situ reduces uncertainty by removing sampling related artifacts and better simulating natural exposures. The amphipod Hyalella azteca and the midge Chironomus Tentans, were enclosed in plastic containers with 149- or 74-mm mesh openings. These chambers were anchored to stream substrates allowing continual water exchange and contact with sediments. Hyallela azteca survival was greater than 80% after 4 weeks of exposure. In situ testing with H. azteca in cold water (
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Toxicity of hexachlorobenzene to Hyalella azteca and Chironomus Tentans in spiked sediment bioassays
Environmental Toxicology and Chemistry, 1997Co-Authors: Timothy R. Barber, Daniel J. Chappie, Phyllis C. Fuchsman, James C. Sferra, F. Charles Newton, Patrick J. SheehanAbstract:Fourteen-day, whole-sediment toxicity tests using the amphipod Hyalella azteca and the midge Chironomus Tentans were conducted on spiked sediment samples representing a range of hexachlorobenzene (HCB) concentrations. High rates of survival and growth relative to controls were observed in both test species. No observed effects concentrations (NOECs) were equal to the highest HCB concentration tested (42 mg/kg, normalized to 1% total organic carbon). Available literature on the aquatic toxicity of this hydrophobic chemical shows an absence of lethal and sublethal effects from exposure to HCB or below water solubility concentrations, and toxicity from exposure to dissolved HCB in sediment porewater therefore would not be expected. Because whole-sediment toxicity tests integrate exposure to HCB dissolved in porewater and adsorbed to particles, it was considered possible that exposure via sediment ingestion could cause toxicity; however, no such effect was observed in this study.
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Evaluation of short-term chronic in situ testing with Hyalella azteca and Chironomus Tentans
1995Co-Authors: Daniel J. Chappie, G. Allen BurtonAbstract:Traditional toxicity testing of simple grab samples is limited by uncertainties arising from extrapolations of laboratory results to field situations. Long term testing in lakes and streams measured the effects of intermittent storm events and contamination from sediments. Aquatic organisms are enclosed in plastic containers with 149 um mesh openings. These chambers were anchored to the bottom allowing continual water exchange and association with sediments to occur. This study was designed to evaluate the effectiveness of chronic in situ testing (one to four weeks of exposure) with Chironomus Tentans and Hyalella azteca. With the addition of 0.01 g of rabbit pellets per chamber as a food source, H. azteca survival was greater than 80% after four weeks of exposure. Testing with H. azteca was limited by cold water temperatures (< 12 C). The midge C. Tentans required a silica sand or shredded paper towel substrate added to the chambers. C. Tentans were more sensitive to handling stress and stream flow than H. azteca. maximizing the usefulness of in situ testing with chronic exposures allows lethal, sub-lethal, and bioaccumulation effects to be measured.
Klaus-dieter Spindler - One of the best experts on this subject based on the ideXlab platform.
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Hormonal regulation of actin and tubulin in an epithelial cell line from Chironomus Tentans.
Archives of Insect Biochemistry and Physiology, 2001Co-Authors: Andreas Fretz, Klaus-dieter SpindlerAbstract:The morphogenetic changes in an epithelial cell line from Chironomus Tentans that are evoked by molting hormones and molting hormone agonists are accompanied by transient changes in the concentration of actin and β-tubulin protein and mRNA. As compared to controls, actin protein and mRNA concentrations increase by about 50%, whereas tubulin reaches maxima of 100% increase. The proportion between globular and filamentous actin remains constant after hormone treatment. Arch. Insect Biochem. Physiol. 41:71–78, 1999. © 1999 Wiley-Liss, Inc.
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Chironomus Tentans (INSECTA, DIPTERA). I. SELECTION AND CHARACTERIZATION OF RESISTANT CLONES
1998Co-Authors: Margarethe Spindler-barth, Klaus-dieter Spindler, Lehrstuhl Far HormonAbstract:SUMMARY Chironomus Tentans cells were cultured in the presence of gradually increasing concentrations of 20-OH-ecdysone or a nonsteroidal molting hormone agonist, the benzoylhydrazine RH 5992, for a period of about 2 yr. From these cultures, subclones were selected, which are resistant to up to 25 tM 20-OH-ecdysone according to morphological (changes in cell shape and cell arrangement) and physiological criteria (acetylcholinesterase induction, secretion of chitinolytic enzymes, thymidine incorporation). Some subclones, selected in the presence of 20-OH-ecdysone, are resistant only to molting hormone, but still respond to RH 5992 morphologically and biochemically, whereas subclones selected in the presence of the benzoylhydrazine showed no reaction neither to 20-OH-ecdysone nor to the hormone agonist. Hormone resistance is stable; 3 mo. after hormone withdrawal, resistant clones still do not respond to renewed exposure to 20-OH-ecdysone or RH 5992, respectively. Because in all resistant subclones tested so far all hormonally regulated responses known from sensitive cells were no longer detectable, it is assumed that the hormone signaling pathway itself is interrupted. Possible mechanisms of hormone resistance were discussed.
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Immunohistochemical localization of ecdysteroid receptor and ultraspiracle in the epithelial cell line from Chironomus Tentans (Insecta, Diptera)
Tissue & cell, 1998Co-Authors: Maria Lammerding-köppel, Margarethe Spindler-barth, Markus Lezzi, Ulrich Drews, E. Steiner, Klaus-dieter SpindlerAbstract:Abstract Ecdysteroid receptor (EcR) and its heterodimerization partner, ultraspiracle (USP), were demonstrated in the epithelial cell line from Chironomus Tentans by immunohistochemistry. In untreated cells both proteins are present in nuclei as well as in granular compartments of the cytosol. At 1 day after addition of 1-μM 20-OH-ecdysone (20E) total immunofluorescence had increased in the nuclei, whereas the cytoplasmic staining had disappeared. At the 2nd and 3rd days all cells within a vesicle appear identical according to morphological criteria, but the EcR and USP immunoreactivity becomes restricted into patches of neighbouring cells. The hormonally induced changes in the pattern of localization of functional ecdysteroid receptor, the heterodimer of EcR and USP, are discussed in relation to similar effects of 20E on acetylcholinesterase and muscarinic acetylcholine receptor distribution in this cell line.
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Effects of 20-hydroxyecdysone on protein synthesis in the epithelial cell line from Chironomus Tentans
Insect Biochemistry and Molecular Biology, 1993Co-Authors: Andreas Fretz, Margarethe Spindler-barth, Andrea Lübbert, Ulrich Markmann-mulisch, Klaus-dieter SpindlerAbstract:Abstract In the epithelial cell line of Chironomus Tentans growth ceases after addition of 20-hydroxyecdysone. Under the influence of moulting hormone the protein pattern changes as shown by 2-dimensional electrophoresis and silver staining. Incorporation of 35 S-labelled methionine reveals qualitative and quantitative changes in the homogenate from the cells and in the proteins secreted into the medium. RNA from cells treated with 20-OH-ecdysone for various times either permanently or with pulses of moulting hormones was expressed in a reticulocyte in vitro translation system. Qualitative changes in the in vitro translated products were first observed after 75 min and continue until day 4 after hormone treatment. A complex pattern of permanent and transient induction and repression of different transcripts is obtained.
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Action of Brassinosteroids on the Epithelial Cell Line from Chironomus Tentans
Zeitschrift für Naturforschung C, 1992Co-Authors: Klaus-dieter Spindler, Andreas Turberg, Margarethe Spindler-barth, Gunter AdamAbstract:: The two brassinosteroids, 22 S,23 S-homobrassinolide and 22 S,23 S-homocastasterone are weak competitors of the binding of [3H]ponasterone A to the intracellular ecdysteroid receptor from the epithelial cell line from Chironomus Tentans. The relative affinities to the ecdysteroid receptor are 0.001 for both brassinosteroids as compared to 20-OH-ecdysone and 0.1 in comparison to ecdysone. Both substances exert morphological effects similar to those observed with 20-OH-ecdysone. Like moulting hormones both brassinosteroids inhibit chitin synthesis. However, these effects were observed only at rather high concentrations (10(-5) to 10(-4) M) which were cytotoxic for 22 S,23 S-homobrassinolide.