The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
J. L. Díez - One of the best experts on this subject based on the ideXlab platform.
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Telomeric puffing induced by heat shock in Chironomus Thummi
Journal of Biosciences, 1996Co-Authors: G. Morcillo, J. L. DíezAbstract:We summarize the most remarkable features of the heat shock inducible large telomeric puffs (T-BRs) in polytene chromosomes of Chironomus Thummi. Kinetic aspects of formation of T-BRs as well as their transcriptional behaviour clearly support the view that T-BRs are components of the heat shock response in Chironomus. Available molecular data indicate T-BRs to include long arrays of 176 bp tandem repeats. A large transcript (> 10 kb) encompas- sing the telomere associated repeat has been detected. Several other similarities between T-BRs of Chironomus and the hsrω genes of Drosophila suggest the T-BRs to be hsrω counterpart in Chironomus.
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Heat shock activation of telomeric sequences in different tissues of Chironomus Thummi.
Experimental cell research, 1994Co-Authors: G. Morcillo, J. L. Díez, Luisa María BotellaAbstract:Abstract The heat shock transcription factor (HSF) has been found by immunocytochemistry using the Drosophila HSF antibody at T-BRIII, a telomeric heat shock-induced puff in polytene chromosomes of Chironomus Thummi salivary glands. Other heat shock-activated loci were also positively stained by the antibody. Neither the telomeres nor other heat shock loci were labeled under control conditions. These results support the presence of a heat shock gene at T-BRIII despite its peculiar location and molecular organization, different from other well-characterized heat shock genes in Diptera. This locus is similarly induced and transcribed under heat shock in Malpighian tubules, another larval polytenic tissue. Transcription from telomeric-associated sequences has also been found in control polytenic and diploid tissues. The meaning of transcription and heat shock activation of telomeric sequences is discussed in relation to the organization of telomeres and compared to possible equivalents in other known heat shock loci.
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Heat-shock induction and cytoplasmic localization of transcripts from telomeric-associated sequences in Chironomus Thummi.
Experimental cell research, 1991Co-Authors: Luisa María Botella, G. Morcillo, Domingo Barettino, J. L. DíezAbstract:Transcription of telomeric-associated sequences has been detected in the salivary gland cells of the larvae Chironomus Thummi. In this species, a heat shock induces puffing at some telomeres, especially at one of the telomeres of chromosome III. We found that this process was concomitant with an increase in the overall telomeric transcript levels. Transcription was also observed in all the telomeres under control conditions, by in situ hybridization, even when these telomeres appeared to be in a nonpuffed state. The telomeric transcripts were found in both, the nuclei and, at higher levels, in the cytoplasmic extracts of salivary gland cells. The heat-shock activation, however, appeared to be restricted to the nuclear level. Telomeric transcription and the peculiar behavior of C. Thummi telomeres after a heat shock are discussed.
Erwin R. Schmidt - One of the best experts on this subject based on the ideXlab platform.
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AN ELECTROSPRAY IONIZATION MASS SPECTROMETRIC STUDY OF THE EXTRACELLULAR HEMOGLOBINS FROM Chironomus Thummi Thummi
Biochimica et biophysica acta, 1998Co-Authors: Brian N. Green, Thomas Hankeln, Erwin R. Schmidt, Gerald Bergtrom, Askar R. Kuchumov, Serge N. VinogradovAbstract:The aquatic larvae of the dipteran, Chironomus Thummi Thummi contain extracellular hemoglobins which exhibit stage-specific expression. We have used maximum entropy-based deconvolution of the complex, multiply charged electrospray ionization mass spectra, to demonstrate the presence of more than 20 components, ranging in mass from 14,417.3 Da to 17,356.5 Da in the 4th instar larvae. Of the 15 major peaks with intensities > 10 relative to 100 for the 14,417.3 Da-component (CTT-IV), only the 15,528.2-Da peak does not correspond to a known amino acid sequence. Since the number of C. Thummi Thummi globin genes now stands at 27, including one cDNA and not counting three that must encode known globins, our results suggest that only a limited number of the globin genes are expressed in the 4th instar larvae.
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Complex Evolution of Tandem-Repetitive DNA in the Chironomus Thummi Species Group
Journal of molecular evolution, 1997Co-Authors: Ralf Ross, Thomas Hankeln, Erwin R. SchmidtAbstract:The subspecies Chironomus Thummi Thummi and C. t. piger display dramatic differences in the copy number and chromosomal localization of a tandemly repeated DNA family (Cla elements). In order to analyze the evolutionary dynamics of this repeat family, we studied the organization of Cla elements in the related outgroup species C. luridus. We find three different patterns of Cla element organization in C. luridus, showing that Cla elements may be either strictly tandem-repetitive or be an integral part of two higher-order tandem repeats (i.e., Hinf[lur] elements, Sal[lur] elements). All three types of Cla-related repeats are localized in the centromeres of C. luridus chromosomes. This suggests that the dispersed chromosomal localization of Cla elements in C. t. Thummi may be the result of an amplification and transposition during evolution of this subspecies.
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The organization, localization and nucleotide sequence of the histone genes of the midge Chironomus Thummi.
Chromosoma, 1991Co-Authors: Thomas Hankeln, Erwin R. SchmidtAbstract:Several histone gene repeating units containing the genes for histones H1, H2A, H2B, H3 and H4 were isolated by screening a genomic DNA library from the midge Chironomus Thummi ssp. Thummi. The nucleotide sequence of one complete histone gene repeating unit was determined. This repeating unit contains one copy of each of the five histone genes in the order and orientation 〈H3 H4〉 〈H2A H2B〉 H1〉. The overall length is 6262 bp. The orientation, nucleotide sequence and inferred amino acid sequence as well as the chromosomal arrangement and localization are different from those reported for Drosophila melanogaster. The codon usage also shows marked differences between Chironomus and Drosophila. Thus the histone gene structure reported for Drosophila is not typical of all insects.
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Complete Nucleotide Sequence of a Hemoglobin Gene Cluster from the Midge Chironomus Thummi piger
Structure and Function of Invertebrate Oxygen Carriers, 1991Co-Authors: Thomas Hankeln, P. Rozynek, C. Luther, Erwin R. SchmidtAbstract:The aquatic larvae of non-biting midges (Chironomidae, Diptera) contain a variety of Hb proteins in their hemolymph that enable them to survive in an anoxic environment (1). In Chironomus Thummi Thummi, 12 different Hb variants have been identified and their amino acid sequences determined (2). Based on these primary structures, the evolutionary relationships between the five monomeric and the s e v e n dimeric Hb proteins have been deduced (2). The two groups are thought to have evolved in two different lineages which separated more than 255 million years ago.
G. Morcillo - One of the best experts on this subject based on the ideXlab platform.
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Telomeric puffing induced by heat shock in Chironomus Thummi
Journal of Biosciences, 1996Co-Authors: G. Morcillo, J. L. DíezAbstract:We summarize the most remarkable features of the heat shock inducible large telomeric puffs (T-BRs) in polytene chromosomes of Chironomus Thummi. Kinetic aspects of formation of T-BRs as well as their transcriptional behaviour clearly support the view that T-BRs are components of the heat shock response in Chironomus. Available molecular data indicate T-BRs to include long arrays of 176 bp tandem repeats. A large transcript (> 10 kb) encompas- sing the telomere associated repeat has been detected. Several other similarities between T-BRs of Chironomus and the hsrω genes of Drosophila suggest the T-BRs to be hsrω counterpart in Chironomus.
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Heat shock activation of telomeric sequences in different tissues of Chironomus Thummi.
Experimental cell research, 1994Co-Authors: G. Morcillo, J. L. Díez, Luisa María BotellaAbstract:Abstract The heat shock transcription factor (HSF) has been found by immunocytochemistry using the Drosophila HSF antibody at T-BRIII, a telomeric heat shock-induced puff in polytene chromosomes of Chironomus Thummi salivary glands. Other heat shock-activated loci were also positively stained by the antibody. Neither the telomeres nor other heat shock loci were labeled under control conditions. These results support the presence of a heat shock gene at T-BRIII despite its peculiar location and molecular organization, different from other well-characterized heat shock genes in Diptera. This locus is similarly induced and transcribed under heat shock in Malpighian tubules, another larval polytenic tissue. Transcription from telomeric-associated sequences has also been found in control polytenic and diploid tissues. The meaning of transcription and heat shock activation of telomeric sequences is discussed in relation to the organization of telomeres and compared to possible equivalents in other known heat shock loci.
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Heat-shock induction and cytoplasmic localization of transcripts from telomeric-associated sequences in Chironomus Thummi.
Experimental cell research, 1991Co-Authors: Luisa María Botella, G. Morcillo, Domingo Barettino, J. L. DíezAbstract:Transcription of telomeric-associated sequences has been detected in the salivary gland cells of the larvae Chironomus Thummi. In this species, a heat shock induces puffing at some telomeres, especially at one of the telomeres of chromosome III. We found that this process was concomitant with an increase in the overall telomeric transcript levels. Transcription was also observed in all the telomeres under control conditions, by in situ hybridization, even when these telomeres appeared to be in a nonpuffed state. The telomeric transcripts were found in both, the nuclei and, at higher levels, in the cytoplasmic extracts of salivary gland cells. The heat-shock activation, however, appeared to be restricted to the nuclear level. Telomeric transcription and the peculiar behavior of C. Thummi telomeres after a heat shock are discussed.
Luisa María Botella - One of the best experts on this subject based on the ideXlab platform.
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Heat shock activation of telomeric sequences in different tissues of Chironomus Thummi.
Experimental cell research, 1994Co-Authors: G. Morcillo, J. L. Díez, Luisa María BotellaAbstract:Abstract The heat shock transcription factor (HSF) has been found by immunocytochemistry using the Drosophila HSF antibody at T-BRIII, a telomeric heat shock-induced puff in polytene chromosomes of Chironomus Thummi salivary glands. Other heat shock-activated loci were also positively stained by the antibody. Neither the telomeres nor other heat shock loci were labeled under control conditions. These results support the presence of a heat shock gene at T-BRIII despite its peculiar location and molecular organization, different from other well-characterized heat shock genes in Diptera. This locus is similarly induced and transcribed under heat shock in Malpighian tubules, another larval polytenic tissue. Transcription from telomeric-associated sequences has also been found in control polytenic and diploid tissues. The meaning of transcription and heat shock activation of telomeric sequences is discussed in relation to the organization of telomeres and compared to possible equivalents in other known heat shock loci.
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Heat-shock induction and cytoplasmic localization of transcripts from telomeric-associated sequences in Chironomus Thummi.
Experimental cell research, 1991Co-Authors: Luisa María Botella, G. Morcillo, Domingo Barettino, J. L. DíezAbstract:Transcription of telomeric-associated sequences has been detected in the salivary gland cells of the larvae Chironomus Thummi. In this species, a heat shock induces puffing at some telomeres, especially at one of the telomeres of chromosome III. We found that this process was concomitant with an increase in the overall telomeric transcript levels. Transcription was also observed in all the telomeres under control conditions, by in situ hybridization, even when these telomeres appeared to be in a nonpuffed state. The telomeric transcripts were found in both, the nuclei and, at higher levels, in the cytoplasmic extracts of salivary gland cells. The heat-shock activation, however, appeared to be restricted to the nuclear level. Telomeric transcription and the peculiar behavior of C. Thummi telomeres after a heat shock are discussed.
Thomas Hankeln - One of the best experts on this subject based on the ideXlab platform.
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AN ELECTROSPRAY IONIZATION MASS SPECTROMETRIC STUDY OF THE EXTRACELLULAR HEMOGLOBINS FROM Chironomus Thummi Thummi
Biochimica et biophysica acta, 1998Co-Authors: Brian N. Green, Thomas Hankeln, Erwin R. Schmidt, Gerald Bergtrom, Askar R. Kuchumov, Serge N. VinogradovAbstract:The aquatic larvae of the dipteran, Chironomus Thummi Thummi contain extracellular hemoglobins which exhibit stage-specific expression. We have used maximum entropy-based deconvolution of the complex, multiply charged electrospray ionization mass spectra, to demonstrate the presence of more than 20 components, ranging in mass from 14,417.3 Da to 17,356.5 Da in the 4th instar larvae. Of the 15 major peaks with intensities > 10 relative to 100 for the 14,417.3 Da-component (CTT-IV), only the 15,528.2-Da peak does not correspond to a known amino acid sequence. Since the number of C. Thummi Thummi globin genes now stands at 27, including one cDNA and not counting three that must encode known globins, our results suggest that only a limited number of the globin genes are expressed in the 4th instar larvae.
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Complex Evolution of Tandem-Repetitive DNA in the Chironomus Thummi Species Group
Journal of molecular evolution, 1997Co-Authors: Ralf Ross, Thomas Hankeln, Erwin R. SchmidtAbstract:The subspecies Chironomus Thummi Thummi and C. t. piger display dramatic differences in the copy number and chromosomal localization of a tandemly repeated DNA family (Cla elements). In order to analyze the evolutionary dynamics of this repeat family, we studied the organization of Cla elements in the related outgroup species C. luridus. We find three different patterns of Cla element organization in C. luridus, showing that Cla elements may be either strictly tandem-repetitive or be an integral part of two higher-order tandem repeats (i.e., Hinf[lur] elements, Sal[lur] elements). All three types of Cla-related repeats are localized in the centromeres of C. luridus chromosomes. This suggests that the dispersed chromosomal localization of Cla elements in C. t. Thummi may be the result of an amplification and transposition during evolution of this subspecies.
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The organization, localization and nucleotide sequence of the histone genes of the midge Chironomus Thummi.
Chromosoma, 1991Co-Authors: Thomas Hankeln, Erwin R. SchmidtAbstract:Several histone gene repeating units containing the genes for histones H1, H2A, H2B, H3 and H4 were isolated by screening a genomic DNA library from the midge Chironomus Thummi ssp. Thummi. The nucleotide sequence of one complete histone gene repeating unit was determined. This repeating unit contains one copy of each of the five histone genes in the order and orientation 〈H3 H4〉 〈H2A H2B〉 H1〉. The overall length is 6262 bp. The orientation, nucleotide sequence and inferred amino acid sequence as well as the chromosomal arrangement and localization are different from those reported for Drosophila melanogaster. The codon usage also shows marked differences between Chironomus and Drosophila. Thus the histone gene structure reported for Drosophila is not typical of all insects.
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Complete Nucleotide Sequence of a Hemoglobin Gene Cluster from the Midge Chironomus Thummi piger
Structure and Function of Invertebrate Oxygen Carriers, 1991Co-Authors: Thomas Hankeln, P. Rozynek, C. Luther, Erwin R. SchmidtAbstract:The aquatic larvae of non-biting midges (Chironomidae, Diptera) contain a variety of Hb proteins in their hemolymph that enable them to survive in an anoxic environment (1). In Chironomus Thummi Thummi, 12 different Hb variants have been identified and their amino acid sequences determined (2). Based on these primary structures, the evolutionary relationships between the five monomeric and the s e v e n dimeric Hb proteins have been deduced (2). The two groups are thought to have evolved in two different lineages which separated more than 255 million years ago.