Articles de revues : « Salivary gland chromosomes »

1

Shahjahan, Reza M., et Farzana Yesmin. « Polytene chromosome maps of the melon fly Bactrocera cucurbitae (Diptera : Tephritidae) ». Genome 45, n^o 6 (1 décembre 2002) : 1167–74. http://dx.doi.org/10.1139/g02-081.

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Standard photographic maps of the polytene chromosomes are presented for the melon fly Bactrocera cucurbitae, a serious pest of fleshy fruits and vegetables. Five larval salivary gland polytene chromosomes (10 polytene arms) were isolated, and their characteristic features and landmarks have been recognized. Banding patterns of each of the polytene arms are presented, where variation in band intensity and puffs appear to reflect fundamental differences in chromosomes. The whole polytene genome has been typically mapped by dividing it into 100 sections and the subsections were lettered. The mitotic chromosomes of larval brain ganglia are also examined, five pairs of autosomes and an XX/XY sex chromosome pair. In addition, a heterochromatic mass corresponding to the sex chromosomes are observed in the polytene nuclei of salivary gland tissue. This investigation showed that B. cucurbitae has excellent cytological material for polytene chromosome analysis and proved to be very useful for obtaining more detailed genetic information on the pest's natural populations.Key words: Bactrocera cucurbitae, salivary gland, banding patterns, polytene maps.

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Zacharopoulou, A. « Cytogenetic analysis of mitotic and salivary gland chromosomes in the Medfly Ceratitis capitata ». Genome 29, n^o 1 (1 février 1987) : 67–71. http://dx.doi.org/10.1139/g87-011.

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The present investigation constitutes a first attempt to study the salivary gland chromosomes of Ceratitis capitata. A photographic representation of the polytene chromosomes from the salivary gland of this species is provided and the tips, as well as some important landmarks, are recognized in each arm. There is an XX/XY pair and five pairs of autosomes in the metaphases, but neither the X nor the Y are represented among the banded polytene chromosomes. Key words: Ceratitis capitata, chromosomes (polytene), chromosomes (mitotic), salivary gland chromosomes.

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Staiber, W. « Unusual germ line limited chromosomes in Acricotopus lucidus (Diptera, Chironomidae) ». Genome 29, n^o 5 (1 octobre 1987) : 702–5. http://dx.doi.org/10.1139/g87-120.

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A small supernumerary polytene chromosome was found during the last 8 years in some rare cases in larval salivary gland cells of Acricotopus lucidus (Diptera, Chironomidae). The chromosome may be derived from the germ line restricted parts of the genome. It consists of a short heterochromatic segment and of euchromatic sections with banding patterns homologous to sections of the short arm of soma chromosome I. When examining male meiosis, an exceptional small germ line limited chromosome was found. It is believed that this chromosome was not always recognized during soma elimination as a germ line limited chromosome, probably because of its partial homology to one of the soma chromosomes, and was then polytenized in salivary gland cells. Another germ line limited chromosome with a characteristic morphology and with a special behavior in differential gonial mitosis was found to have existed for more than 12 years in a laboratory stock. In differential gonial mitosis this special germ line limited chromosome partly pairs with the long arm of soma chromosome I. The present results strongly support the idea that the germ line limited chromosomes of A. lucidus are derived from the soma chromosomes, and show that chromosomes of the germ line restricted part of the genome can persist for many generations in a laboratory stock in spite of complex chromosome elimination mechanisms in the primary germ cells. Key words: germ line limited chromosomes, supernumerary polytene chromosome, salivary gland, Acricotopus lucidus.

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Zambetaki, Anna, Kleanthis Kleanthous et Penelope Mavragani-Tsipidou. « Cytogenetic analysis of Malpighian tubule and salivary gland polytene chromosomes of Bactrocera oleae (Dacus oleae) (Diptera : Tephritidae) ». Genome 38, n^o 6 (1 décembre 1995) : 1070–81. http://dx.doi.org/10.1139/g95-143.

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Photomaps of the Malpighian tubule and the salivary gland polytene chromosomes of Bactrocera oleae (Dacus oleae) are presented and compared with those of the fat body. Five polytene chromosomes (10 polytene arms) corresponding to the five autosomes of the mitotic nuclei, as well as a heterochromatic mass corresponding to the sex chromosomes, are observed in the nuclei of the three somatic tissues. The most prominent features of each polytene chromosome, the reverse tandem duplications, as well as the rather unusual ectopic pairing of the telomeric regions of different chromosome arms, are described. The constancy of the banding pattern based on the analysis of the three larval tissues is discussed.Key words: Bactrocera oleae (Dacus oleae), polytene chromosomes, salivary gland, Malpighian tubule, banding pattern.

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Drosopoulou, Elena, Ifigeneia Nakou et Penelope Mavragani-Tsipidou. « The Bactrocera oleae genome : localization of nine genes on the polytene chromosomes of the olive fruit fly (Diptera : Tephritidae) ». Genome 57, n^o 10 (octobre 2014) : 573–76. http://dx.doi.org/10.1139/gen-2014-0172.

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Four homologous and five heterologous gene-specific sequences have been mapped by in situ hybridization on the salivary gland polytene chromosomes of the olive fruit fly, Bactrocera oleae. The nine genes were dispersed on four of the five autosomal chromosomes, thus enriching the available set of chromosome landmarks for this major agricultural pest. Present data further supports the proposed chromosome homologies among B. oleae, Ceratitis capitata, and Drosophila melanogaster and the idea of the conservation of chromosomal element identity throughout dipteran evolution.

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Verma, R. K., Subasini Patnaik, R. Prasad et C. C. Das. « Salivary Gland Chromosomes ofCulex Quinquefasciatus ». Caryologia 40, n^o 1-2 (janvier 1987) : 99–108. http://dx.doi.org/10.1080/00087114.1987.10797813.

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Zambetaki, Anna, Antigone Zacharopoulou, Zacharias G. Scouras et Penelope Mavragani-Tsipidou. « The genome of the olive fruit fly Bactrocera oleae : localization of molecular markers by in situ hybridization to the salivary gland polytene chromosomes ». Genome 42, n^o 4 (1 août 1999) : 744–51. http://dx.doi.org/10.1139/g99-017.

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Nine specific DNA probes (genomic or cDNA) from Ceratitis capitata have been mapped by in situ hybridization to the salivary gland polytene chromosomes of the olive fruit fly Bactrocera oleae, a major agricultural pest, thus establishing molecular markers for the 5 autosomal chromosomes. Taking into account the present results, as well as previous data obtained mainly by in situ hybridizations, chromosomal homologies among B. oleae, C. capitata and B. tryoni are established. Data show extensive linkage group conservation among the 3 taxa of the economically important and globally distributed family, the Tephritidae.Key words: Bactrocera oleae, Tephritidae, salivary gland, polytene chromosomes, in situ hybridization, mapping.

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Hochstrasser, M., D. Mathog, Y. Gruenbaum, H. Saumweber et J. W. Sedat. « Spatial organization of chromosomes in the salivary gland nuclei of Drosophila melanogaster. » Journal of Cell Biology 102, n^o 1 (1 janvier 1986) : 112–23. http://dx.doi.org/10.1083/jcb.102.1.112.

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Using a computer-based system for model building and analysis, three-dimensional models of 24 Drosophila melanogaster salivary gland nuclei have been constructed from optically or physically sectioned glands, allowing several generalizations about chromosome folding and packaging in these nuclei. First and most surprising, the prominent coiling of the chromosomes is strongly chiral, with right-handed gyres predominating. Second, high frequency appositions between certain loci and the nuclear envelope appear almost exclusively at positions of intercalary heterochromatin; in addition, the chromocenter is always apposed to the envelope. Third, chromosomes are invariably separated into mutually exclusive spatial domains while usually extending across the nucleus in a polarized (Rabl) orientation. Fourth, the arms of each autosome are almost always juxtaposed, but no other relative arm positions are strongly favored. Finally, despite these nonrandom structural features, each chromosome is found to fold into a wide variety of different configurations. In addition, a set of nuclei has been analyzed in which the normally aggregrated centromeric regions of the chromosomes are located far apart from one another. These nuclei have the same architectural motifs seen in normal nuclei. This implies that such characteristics as separate chromosome domains and specific chromosome-nuclear envelope contacts are largely independent of the relative placement of the different chromosomes within the nucleus.

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Hoshizaki, Deborah K., Bonnie M. Dlott, Geoffrey L. Joslyn et Steven K. Beckendorf. « Genetic localization of a regulatory site necessary for the production of the glue protein P5 in Drosophila melanogaster ». Genetical Research 49, n^o 2 (avril 1987) : 111–19. http://dx.doi.org/10.1017/s0016672300026902.

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SummaryThe glue proteins are products of a developmentally regulated gene family. These genes are transcriptionally active during the third larval instar and code for the major protein products of salivary glands. The activity of several of the genes can be visualized as intermoult puffs in the polytene salivary gland chromosomes. The amount of one of these proteins, P5, varies widely among wild-type strains. We have used biochemical and genetic methods to investigate the source of this variation. The results of in vitro translation of salivary gland RNA suggest that the variation occurs pretranslationally. Genetic mapping experiments showed that sites on several chromosomes can modulate the amount of P5, but that one site on the third chromosome determines the absence and presence of this protein. We have mapped this glue protein gene, called GP5, to the interval between bx (3–58·8) and sr (3–62·0) which also includes the intermoult puff at 90BC. We discuss the relationship between P5 and the glue protein gene Sgs-5 which is also located at 90BC.

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Zhang, P., et A. C. Spradling. « The Drosophila salivary gland chromocenter contains highly polytenized subdomains of mitotic heterochromatin. » Genetics 139, n^o 2 (1 février 1995) : 659–70. http://dx.doi.org/10.1093/genetics/139.2.659.

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Abstract Peri-centromeric regions of Drosophila melanogaster chromosomes appear heterochromatic in mitotic cells and become greatly underrepresented in giant polytene chromosomes, where they aggregate into a central mass called the chromocenter. We used P elements inserted at sites dispersed throughout much of the mitotic heterochromatin to analyze the fate of 31 individual sites during polytenization. Analysis of DNA sequences flanking many of these elements revealed that middle repetitive or unique sequence DNAs frequently are interspersed with satellite DNAs in mitotic heterochromatin. All nine Y chromosome sites tested were underrepresented > 20-fold on Southern blots of polytene DNA and were rarely or never detected by in situ hybridization to salivary gland chromosomes. In contrast, nine tested insertions in autosomal centromeric heterochromatin were represented fully in salivary gland DNA, despite the fact that at least six were located proximal to known blocks of satellite DNA. The inserted sequences formed diverse, site-specific morphologies in the chromocenter of salivary gland chromosomes, suggesting that domains dispersed at multiple sites in the centromeric heterochromatin of mitotic chromosomes contribute to polytene beta-heterochromatin. We suggest that regions containing heterochromatic genes are organized into dispersed chromatin configurations that are important for their function in vivo.

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Kounatidis, Ilias, Nikolaos Papadopoulos, Kostas Bourtzis et Penelope Mavragani-Tsipidou. « Genetic and cytogenetic analysis of the fruit fly Rhagoletis cerasi (Diptera : Tephritidae) ». Genome 51, n^o 7 (juillet 2008) : 479–91. http://dx.doi.org/10.1139/g08-032.

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The European cherry fruit fly, Rhagoletis cerasi , is a major agricultural pest for which biological, genetic, and cytogenetic information is limited. We report here a cytogenetic analysis of 4 natural Greek populations of R. cerasi, all of them infected with the endosymbiotic bacterium Wolbachia pipientis . The mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of this pest species are presented here. The mitotic metaphase complement consists of 6 pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement has shown a total of 5 long chromosomes (10 polytene arms) that correspond to the 5 autosomes of the mitotic nuclei and a heterochromatic mass corresponding to the sex chromosomes. The most prominent landmarks of each polytene chromosome, the “weak points”, and the unusual asynapsis of homologous pairs of polytene chromosomes at certain regions of the polytene elements are also presented and discussed.

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George, Phillip, Nicholas A. Kinney, Jiangtao Liang, Alexey V. Onufriev et Igor V. Sharakhov. « Three-dimensional Organization of Polytene Chromosomes in Somatic and Germline Tissues of Malaria Mosquitoes ». Cells 9, n^o 2 (1 février 2020) : 339. http://dx.doi.org/10.3390/cells9020339.

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Spatial organization of chromosome territories and interactions between interphase chromosomes themselves, as well as with the nuclear periphery, play important roles in epigenetic regulation of the genome function. However, the interplay between inter-chromosomal contacts and chromosome-nuclear envelope attachments in an organism’s development is not well-understood. To address this question, we conducted microscopic analyses of the three-dimensional chromosome organization in malaria mosquitoes. We employed multi-colored oligonucleotide painting probes, spaced 1 Mb apart along the euchromatin, to quantitatively study chromosome territories in larval salivary gland cells and adult ovarian nurse cells of Anopheles gambiae, An. coluzzii, and An. merus. We found that the X chromosome territory has a significantly smaller volume and is more compact than the autosomal arm territories. The number of inter-chromosomal, and the percentage of the chromosome–nuclear envelope, contacts were conserved among the species within the same cell type. However, the percentage of chromosome regions located at the nuclear periphery was typically higher, while the number of inter-chromosomal contacts was lower, in salivary gland cells than in ovarian nurse cells. The inverse correlation was considerably stronger for the autosomes. Consistent with previous theoretical arguments, our data indicate that, at the genome-wide level, there is an inverse relationship between chromosome-nuclear envelope attachments and chromosome–chromosome interactions, which is a key feature of the cell type-specific nuclear architecture.

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Hilliker, Arthur J. « Assaying chromosome arrangement in embryonic interphase nuclei of Drosophila melanogaster by radiation induced interchanges ». Genetical Research 47, n^o 1 (février 1986) : 13–18. http://dx.doi.org/10.1017/s0016672300024459.

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SummaryDespite recent advances in our understanding of chromatin ultrastructure, little is known of the arrangement of chromosomes during interphase, the portion of the cell cycle associated with somatic gene transcription. An experimental procedure is described which has allowed the determination of the nature of the relative arrangement during interphase of chromosomes in a specific diploid cell type of Drosophila, the salivary gland anlage of the 10–14-h-old embryo. At this stage of development the salivary gland cells have ceased mitotic divisions. Embryos of 10–14 h in age were irradiated with 12000 rads of gamma radiation and then allowed to develop into third instar larvae. The polytene chromosomes of these larvae were examined for radiation-induced interchanges. From the distribution of observed interchanges, three major features of interphase chromosome arrangement were inferred. (1) Each euchromatic chromosomal arm occupies a specific domain within the interphase nucleus which does not appreciably overlap with those of other arms. (2) Within these chromosomal domains DNA folding is very extensive. (3) The heterochromatic regions of each chromosomal arm are sequestered from the euchromatic regions. An additional point of interest concerns the nature of the interchanges observed. No reciprocal interchanges were observed – all appeared to be partial exchanges, possibly subchromatid interchanges involving only one DNA strand from each of the two exchange sites.

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Zacharopoulou, A., K. Bourtzis et Ph Kerremans. « A comparison of polytene chromosomes in salivary glands and orbital bristle trichogen cells in Ceratitis capitata ». Genome 34, n^o 2 (1 avril 1991) : 215–19. http://dx.doi.org/10.1139/g91-034.

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The banding patterns of polytene chromosomes in different tissues of the Mediterranean fruit fly, Ceratitis capitata, vary to such an extent that homologous chromosomes cannot be recognised. However, analyses of autosomal breakpoints in several translocation strains allowed chromosomes from the two tissues to be aligned despite their difference in banding pattern. These results were discussed, considering the different hypotheses of the origin and biological significance of polytene chromosome bands.Key words: polytene chromosomes, salivary gland chromosomes, orbital bristle trichogen cell chromosomes, Ceratitis capitata.

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Garcia-Martinez, V., E. Hernandez-Ortiz, C. S. Zepeta-Cisneros, A. S. Robinson, A. Zacharopoulou et G. Franz. « Mitotic and polytene chromosome analysis in the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera : Tephritidae) ». Genome 52, n^o 1 (janvier 2009) : 20–30. http://dx.doi.org/10.1139/g08-099.

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The present study constitutes the first attempt to construct a polytene chromosome map of an Anastrepha species, Anastrepha ludens (Loew), a major agricultural pest. The mitotic karyotype has a diploid complement of 12 acrocentric chromosomes, including five pairs of autosomes and an XX/XY sex chromosome pair. The analysis of salivary gland polytene chromosomes has shown a total number of five polytene elements that correspond to the five autosomes. The characteristic features and the most prominent landmarks of each chromosome are described. By comparing chromosome banding patterns, the possible chromosomal homology between A. ludens and Ceratitis capitata (Wiedemann) is presented. This work shows that polytene maps of A. ludens are suitable for cytogenetic studies in this species and may be used as reference for other Anastrepha species, most of which are also serious agricultural pests.

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Zacharopoulou, A. « Polytene chromosome maps in the Medfly Ceratitis capitata ». Genome 33, n^o 2 (1 avril 1990) : 184–97. http://dx.doi.org/10.1139/g90-030.

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Polytene chromosome maps of the five autosomes from salivary gland cells in Ceratitis capitata are presented, and the more characteristic features of each element are described. The correlation of the polytene elements to miotic chromosomes and linkage groups is established by using various Y-autosome and autosome-autosome translocation lines. Two loci, dp (black pupal case) and w (white pupal case), are mapped to the third and fifth chromosome, respectively. In addition to the polytene maps presented, some extra figures of specific chromosomal regions are given for easier identification of each polytene element.Key words: polytene chromosome maps, Ceratitis capitata.

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Kolesnikova, Tatyana D., Alexandra V. Kolodyazhnaya, Galina V. Pokholkova, Veit Schubert, Viktoria V. Dovgan, Svetlana A. Romanenko, Dmitry Yu Prokopov et Igor F. Zhimulev. « Effects of Mutations in the Drosophila melanogaster Rif1 Gene on the Replication and Underreplication of Pericentromeric Heterochromatin in Salivary Gland Polytene Chromosomes ». Cells 9, n^o 6 (19 juin 2020) : 1501. http://dx.doi.org/10.3390/cells9061501.

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In Drosophila salivary gland polytene chromosomes, a substantial portion of heterochromatin is underreplicated. The combination of mutations SuURES and Su(var)3-906 results in the polytenization of a substantial fraction of unique and moderately repeated sequences but has almost no effect on satellite DNA replication. The Rap1 interacting factor 1 (Rif) protein is a conserved regulator of replication timing, and in Drosophila, it affects underreplication in polytene chromosomes. We compared the morphology of pericentromeric regions and labeling patterns of in situ hybridization of heterochromatin-specific DNA probes between wild-type salivary gland polytene chromosomes and the chromosomes of Rif1 mutants and SuUR Su(var)3-906 double mutants. We show that, despite general similarities, heterochromatin zones exist that are polytenized only in the Rif1 mutants, and that there are zones that are under specific control of Su(var)3-9. In the Rif1 mutants, we found additional polytenization of the largest blocks of satellite DNA (in particular, satellite 1.688 of chromosome X and simple satellites in chromosomes X and 4) as well as partial polytenization of chromosome Y. Data on pulsed incorporation of 5-ethynyl-2′-deoxyuridine (EdU) into polytene chromosomes indicated that in the Rif1 mutants, just as in the wild type, most of the heterochromatin becomes replicated during the late S phase. Nevertheless, a significantly increased number of heterochromatin replicons was noted. These results suggest that Rif1 regulates the activation probability of heterochromatic origins in the satellite DNA region.

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Kress H, P., L. Lucka, U. Swida, E. Thuroff et U. Klemm. « Genes from two intermoult puffs in Drosophila virilis polytene chromosomes are differentially transcribed during larval development ». Development 108, n^o 2 (1 février 1990) : 261–67. http://dx.doi.org/10.1242/dev.108.2.261.

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Genes from two Drosophila virilis intermoult puffs were isolated by microcloning. From puff 16A on the X-chromosome a 2.9 kb DNA fragment was obtained, which hybridizes with three transcripts. Two of them represent the mRNAs for larval glue proteins. They are found in different abundancies in third larval instar salivary glands, but also in minor amounts in midgut and in fat body. In puff 55E on chromosome III two genes were identified. They are transcribed exclusively in salivary glands during all three larval instars. Therefore, their products must be related to another gland-specific function, which is sustained throughout larval life.

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WUELKER, WOLFGANG, JON MARTIN, IYA I. KIKNADZE, JAMES E. SUBLETTE et SUSANNE MICHIELS. « Chironomus blaylocki sp. n. and C. bifurcatus sp. n., North American species near the base of the decorus-group (Diptera : Chironomidae) ». Zootaxa 2023, n^o 1 (27 février 2009) : 28–46. http://dx.doi.org/10.11646/zootaxa.2023.1.2.

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Two species of the cytologically defined Chironomus decorus-group, C. bifurcatus sp. n. and C. blaylocki sp. n., are described on the basis of their salivary gland polytene chromosomes and larval morphology, with the associated male and pupa of C. bifurcatus and the putative male of C. blaylocki included as paratypes. The banding patterns of the salivary gland chromosomes indicate that these species are near the base of the cytologically defined decorus-group. The cytology and adults of these new species are compared with those of a number of other undescribed North American decorus-group species to demonstrate that they are distinct species.

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Booth, DR, CA Green et JH Bryan. « The Larval Salivary-Gland Polytene Chromosomes of Anopheles (Cellia) Annulipes Sl Walker (Diptera, Culicidae) ». Australian Journal of Zoology 35, n^o 3 (1987) : 247. http://dx.doi.org/10.1071/zo9870247.

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A photomap of the larval salivary gland chromosomes of An. annulipes from colony material arbitrarily chosen as standard for this taxon is presented. Also illustrated are seven types of X chromosomes which have been revealed in this multi-species taxon.

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HAAPALA, O. K. « The organization of chromosome fibrils in salivary-gland chromosomes of Drosophila melanogaster ». Hereditas 75, n^o 1 (12 février 2009) : 61–66. http://dx.doi.org/10.1111/j.1601-5223.1973.tb01142.x.

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Weber, E. Andreas, et Jörg Grunewald. « Cytotaxonomic differentiation of Wilhelmia equina (Linné, 1747) and Wilhelmia lineata (Meigen, 1804) (Diptera : Simuliidae) ». Genome 32, n^o 4 (1 août 1989) : 589–95. http://dx.doi.org/10.1139/g89-486.

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In most cases the larvae of Wilhelmia equina and W. lineata cannot be distinguished by using classical morphological features. The morphological characteristics of the salivary gland polytene chromosomes allow one to differentiate clearly between the two species. Characteristic for W. equina are the extended region between the centromere, Ctr (transformed centromere), and the nucleolus organizer, NO, in IS, the definitive position of RB (ring of Balbiani) and bulge in IIS, and the fan-shaped IIIL telomere. The chromosomes of W. lineata are marked by complex chromosomal polymorphisms, the altered position of RB and bulge on IIS and by a strong ectopic pairing of centromeres. The comparison of banding patterns provides several intraspecific polymorphic inversions and interspecific fixed rearrangements for species diagnosis. Partial chromosome maps were established. The comparison of the chromosomal banding pattern of Wilhelmia with that of the Simulium standard reveals a whole-arm interchange between chromosomes I and II in Wilhelmia identical with that in Metomphalus, Prosimulium vernale, a form of P. mixtum, and Metacnephia.Key words: cytotaxonomy, Simuliidae, Wilhelmia equina, Wilhelmia lineata, larvae.

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Hochstrasser, M., et J. W. Sedat. « Three-dimensional organization of Drosophila melanogaster interphase nuclei. I. Tissue-specific aspects of polytene nuclear architecture. » Journal of Cell Biology 104, n^o 6 (1 juin 1987) : 1455–70. http://dx.doi.org/10.1083/jcb.104.6.1455.

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Interphase chromosome organization in four different Drosophila melanogaster tissues, covering three to four levels of polyteny, has been analyzed. The results are based primarily on three-dimensional reconstructions from unfixed tissues using a computer-based data collection and modeling system. A characteristic organization of chromosomes in each cell type is observed, independent of polyteny, with some packing motifs common to several or all tissues and others tissue-specific. All chromosomes display a right-handed coiling chirality, despite large differences in size and degree of coiling. Conversely, in each cell type, the heterochromatic centromeric regions have a unique structure, tendency to associate, and intranuclear location. The organization of condensed nucleolar chromatin is also tissue-specific. The tightly coiled prothoracic gland chromosomes are arrayed in a similar fashion to the much larger salivary gland chromosomes described previously, having polarized orientations, nonintertwined spatial domains, and close packing of the arms of each autosome, whereas hindgut and especially the unusually straight midgut chromosomes display striking departures from these regularities. Surprisingly, gut chromosomes often appear to be broken in the centric heterochromatin. Severe deformations of midgut nuclei observed during gut contractions in living larvae may account for their unusual properties. Finally, morphometric measurements of chromosome and nuclear dimensions provide insights into chromosome growth and substructure and also suggest an unexpected parallel with diploid chromatin organization.

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Mavragani-Tsipidou, P., Z. G. Scouras et A. Natsiou-Voziki. « The Balbiani ring and the polytene chromosomes of Drosophila bicornuta ». Genome 35, n^o 1 (1 février 1992) : 64–67. http://dx.doi.org/10.1139/g92-011.

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A study of the BR1 and of the most prominent puffs during larval development and after in vitro ecdysterone treatment, as well as of the banding pattern and inverted tandem chromosomal duplications of the salivary gland chromosomes of Drosophila bicornuta, is presented in this report. These data are compared and discussed with those of D. auraria and D. serrata, two other montium species.Key words: Drosophila, Balbiani ring, duplications, ecdysterone.

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Hochstrasser, M., et J. W. Sedat. « Three-dimensional organization of Drosophila melanogaster interphase nuclei. II. Chromosome spatial organization and gene regulation. » Journal of Cell Biology 104, n^o 6 (1 juin 1987) : 1471–83. http://dx.doi.org/10.1083/jcb.104.6.1471.

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In the preceding article we compared the general organization of polytene chromosomes in four different Drosophila melanogaster cell types. Here we describe experiments aimed at testing for a potential role of three-dimensional chromosome folding and positioning in modulating gene expression and examining specific chromosome interactions with different nuclear structures. By charting the configurations of salivary gland chromosomes as the cells undergo functional changes, it is shown that loci are not repositioned within the nucleus when the pattern of transcription changes. Heterologous loci show no evidence of specific physical interactions with one another in any of the cell types. However, a specific subset of chromosomal loci is attached to the nuclear envelope, and this subset is extremely similar in at least two tissues. In contrast, no specific interactions between any locus and the nucleolus are found, but the base of the X chromosome, containing the nucleolar organizer, is closely linked to this organelle. These results are used to evaluate models of gene regulation that involve the specific intranuclear positioning of gene sequences. Finally, data are presented on an unusual class of nuclear envelope structures, filled with large, electron-dense particles, that are usually associated with chromosomes.

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Kuvangkadilok, Chaliow, Suwannee Phayuhasena et Visut Baimai. « Population cytogenetic studies on Simulium feuerborni Edwards (Diptera : Simuliidae) from northern Thailand ». Genome 42, n^o 1 (1 février 1999) : 80–86. http://dx.doi.org/10.1139/g98-106.

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A standard photographic map of Simulium feuerborni (Diptera: Simuliidae) was constructed from larval salivary gland polytene chromosomes and is described herein. Analysis of polytene chromosomes was made from wild larvae collected from the four populations at Doi Inthanon National Park, Chiang Mai Province, northern Thailand. Simulium feuerborni has three pairs of chromosomes (2n = 6) which are arranged from the longest to the shortest. Chromosome I is metacentric while chromosomes II and III are submetacentric. A total of six simple paracentric inversions have been detected in these natural populations of S. feuerborni. These inversions (IS-1, IL-1, IIL-1, IIL-2, IIIS-1, IIIL-1) occurred in all chromosome arms except for the arm IIS. Significant deviation from Hardy-Weinberg equilibrium has been observed in inversion IIIL-1 at Hui Sai Luaeng suggesting the existence of two gene pools in this population. There is no indication of sex linkage associated with an inversion sequence in these populations. Thus, the X and Y chromosomes of S. feuerborni could not be recognized in this study.Key words: Simulium, polytene chromosome map, inversion polymorphisms

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Whiting, J. H., M. D. Pliley, J. L. Farmer et D. E. Jeffery. « In situ hybridization analysis of chromosomal homologies in Drosophila melanogaster and Drosophila virilis. » Genetics 122, n^o 1 (1 mai 1989) : 99–109. http://dx.doi.org/10.1093/genetics/122.1.99.

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Abstract Twenty-four biotin-labeled recombinant-DNA probes which contained putative unique-sequence Drosophila melanogaster DNA were hybridized to larval salivary-gland chromosomes of D. melanogaster and Drosophila virilis. All probes hybridized to D. melanogaster chromosomes at the expected sites. However, one probe hybridized to at least 16 additional sites, and one hybridized to one additional site. Thirteen probes hybridized strongly to D. virilis chromosomes, four hybridized weakly and infrequently, and seven did not hybridize. Probes representing two multigene families (beta-tubulin and yolk-protein) hybridized as would be expected if all sites had been conserved in the two species on the same chromosomal elements. The multiple hybridization sites of a third probe which may represent a multigene family were also conserved. The results were consistent with H.J. Muller's proposal that chromosomal elements have been conserved during evolution of this genus.

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JABLONSKA-BARNA, IZABELA, PARASKEVA MICHAILOVA, ANDRZEJ KOWNACKI et PETER H. LANGTON. « The karyotype of Chironomus acerbiphilus Tokunaga, 1939 (Diptera : Chironomidae) from Poland ». Zootaxa 2359, n^o 1 (15 février 2010) : 65. http://dx.doi.org/10.11646/zootaxa.2359.1.6.

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The chromosome set of Chironomus crassimanus Strenzke, 1959 and pictures of its salivary gland chromosomes were presented by Keyl and Keyl (1959) and Keyl (1962). Keyl (1962) described the band sequence of chromosome AE compared with that of other Chironomus species. Later, Michailova (1989) described the chromosome markers of this species using material from Bulgaria. Martin (2006) indicated that the banding patterns of arms A and E of Chironomus acerbiphilus Tokunaga, 1939 are as in C. crassimanus and consequently suggested synonymy. Our study presents the karyotype of Chironomus acerbiphilus (= C. crassimanus) from Poland. This species is new for the Polish fauna.

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Rafael, Míriam Silva, Leticia Cegatti Bridi, Igor V. Sharakhov, Osvaldo Marinotti, Maria V. Sharakhova, Vladimir Timoshevskiy, Giselle Moura Guimarães-Marques et al. « Physical Mapping of the Anopheles (Nyssorhynchus) darlingi Genomic Scaffolds ». Insects 12, n^o 2 (15 février 2021) : 164. http://dx.doi.org/10.3390/insects12020164.

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The genome assembly of Anopheles darlingi consists of 2221 scaffolds (N50 = 115,072 bp) and has a size spanning 136.94 Mbp. This assembly represents one of the smallest genomes among Anopheles species. Anopheles darlingi genomic DNA fragments of ~37 Kb were cloned, end-sequenced, and used as probes for fluorescence in situ hybridization (FISH) with salivary gland polytene chromosomes. In total, we mapped nine DNA probes to scaffolds and autosomal arms. Comparative analysis of the An. darlingi scaffolds with homologous sequences of the Anopheles albimanus and Anopheles gambiae genomes identified chromosomal rearrangements among these species. Our results confirmed that physical mapping is a useful tool for anchoring genome assemblies to mosquito chromosomes.

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Makunin, I. V., E. I. Volkova, E. S. Belyaeva, E. N. Nabirochkina, V. Pirrotta et I. F. Zhimulev. « The Drosophila Suppressor of Underreplication Protein Binds to Late-Replicating Regions of Polytene Chromosomes ». Genetics 160, n^o 3 (1 mars 2002) : 1023–34. http://dx.doi.org/10.1093/genetics/160.3.1023.

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Abstract In many late-replicating euchromatic regions of salivary gland polytene chromosomes, DNA is underrep-resented. A mutation in the SuUR gene suppresses underreplication and leads to normal levels of DNA polytenization in these regions. We identified the SuUR gene and determined its structure. In the SuUR mutant stock a 6-kb insertion was found in the fourth exon of the gene. A single SuUR transcript is present at all stages of Drosophila development and is most abundant in adult females and embryos. The SuUR gene encodes a protein of 962 amino acids whose putative sequence is similar to the N-terminal part of SNF2/SWI2 proteins. Staining of salivary gland polytene chromosomes with antibodies directed against the SuUR protein shows that the protein is localized mainly in late-replicating regions and in regions of intercalary and pericentric heterochromatin.

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Bedo, D. G. « Polytene chromosome mapping in Ceratitis capitata (Diptera : Tephritidae) ». Genome 29, n^o 4 (1 août 1987) : 598–611. http://dx.doi.org/10.1139/g87-101.

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Polytene chromosome reference maps of the five autosomes of Ceratitis capitata from male pupal orbital bristle trichogen cells are presented and a correlation is established between two of them and the two largest of the five autosomes in the haploid mitotic complement. Characteristic features of each chromosome are described identifying areas that are difficult to analyze and noting the existence of common alternative band expression. A quantitative analysis of the mitotic karyotype of C. capitata indicates that the two smallest autosome pairs cannot be reliably distinguished. This may present problems with future attempts to establish homologies between the remaining mitotic and polytene chromosomes. A comparison of polytene chromosome banding patterns from salivary gland and trichogen cells failed to find any homologous regions, or even to identify homologous chromosomes. The banding differences are not explained by variation in puffing patterns, heterochromatin expression, or polyteny levels, but appear to reflect fundamental differences in banding patterns of the chromosomes in each tissue. Key words: Ceratitis capitata, polytene chromosome map, mitotic chromosome measurements.

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Pisa, E. K., P. Pisa, H. I. Kang et R. I. Fox. « High frequency of t(14;18) translocation in salivary gland lymphomas from Sjögren's syndrome patients. » Journal of Experimental Medicine 174, n^o 5 (1 novembre 1991) : 1245–50. http://dx.doi.org/10.1084/jem.174.5.1245.

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Sjögren's syndrome (SS) is a chronic autoimmune disorder characterized by lymphocytic infiltration of the salivary and lacrimal glands. These patients have a markedly increased frequency of developing non-Hodgkin's lymphoma in their salivary glands and cervical lymph nodes. Translocations of proto-oncogene bcl-2 t(14;18) were observed in five of seven SS-associated lymphomas by Southern blot analysis. Using primers specific for chromosomes 14 and 18, translocation of the proto-oncogene bcl-2 was detected by polymerase chain reaction (PCR) in all five lymphomas positive by Southern blot analysis. Among SS patients lacking clinical evidence of coexistent lymphoma, no bcl-2 translocations were detected in 50 consecutive salivary gland biopsies. Of particular interest, pre-lymphoma biopsies were available from the seven SS patients who subsequently developed lymphoma and these DNA samples lacked detectable t(14;18) translocations even though they exhibited oligoclonal rearrangements of their immunoglobulin genes. We conclude that the great sensitivity of PCR can help us in detecting early onset of lymphoma in SS patients and aid in understanding the transition from autoimmunity to lymphoma.

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Kraai, Tania L., Garth T. Olson, Therese J. Bocklage et Hozier John. « R411 – FISH of Salivary Tumors to Enhance Diagnostic Accuracy ». Otolaryngology–Head and Neck Surgery 139, n^o 2_suppl (août 2008) : P180—P181. http://dx.doi.org/10.1016/j.otohns.2008.05.565.

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Problem Fine needle aspiration biopsy (FNAB) is used to triage patients with salivary tumors. Distinguishing benign from malignant is difficult on cytology features and immunohistochemistry alone, leading sometimes to an incorrect surgical resection. Therefore, we evaluated whether fluorescent in situ hybridization (FISH) could be performed routinely on salivary gland tumor FNAB's, potentially to improve diagnostic accuracy. Methods Pathology files from our institution were searched for patients with salivary gland tumors. We collected data on 74 tumors: 25 benign (18 pleomorphic adenoma and 7 Warthin's tumors) and 49 malignant (miscellaneous including adenoid cystic carcinoma, mucoepidermoid carcinoma and acinic cell carcinoma, among others). Clinical presentation, staging, and follow-up information were obtained. Representative tumor blocks were disaggregated, converted to nuclear preps, and analyzed for aneuploidies of chromosomes 3, 7, 9, 11, and 19 using FISH. A novel technique creating a CMA (cytology microarray) enabled testing of multiple samples on one glass slide. Signal quantitation was performed using a Metasystems instrument. Shrunken centroid analysis was used to test for significant differences in the benign versus malignant group. Results Six tumors exhibited trisomies (8 percent); those few were exclusively limited to the malignant tumors. The tumor preps yielded adequate cellularity in 90% percent, and the CMA technique was time and cost efficient. Conclusion In a large number of salivary gland tumors, we found that chromosome copy number abnormalities do not occur with high enough frequency to enhance diagnostic accuracy. When trisomy occurs, it more likely is associated with malignancy. Significance Polyploidy seen on FISH analysis of the FNA of salivary tumors does not enhance diagnostic accuracy.

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Sorsa, V. « Distribution of chromomeres as a basis of chromosomal coiling ». Journal of Cell Science 80, n^o 1 (1 février 1986) : 193–205. http://dx.doi.org/10.1242/jcs.80.1.193.

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Periodicity in the distribution of prominent bands was analysed from the light and electron microscopic maps of salivary gland chromosomes of Drosophila melanogaster. The data obtained indicate that a similar distribution of prominent chromosomes in an individual interphase chromatid results in a unilateral accumulation of chromatin at the chromonema stage, if the helical axis of chromonema consists of approximately 5–9 interchromomere + chromomere units per turn. Orientation of the largest chromomeres mainly on one lateral half and the smallest chromomeres mainly on the opposite lateral half of the chromonema apparently bends it to form the chromosomal ‘macro’ coil. Thus the increase in DNA content in the chromomeric loops located at specific intervals along the chromatids may have an important role in the evolution of coiling hierarchy in the eukaryotic chromosomes.

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Bienz-Tadmor, B., H. S. Smith et S. A. Gerbi. « The promoter of DNA puff gene II/9-1 of Sciara coprophila is inducible by ecdysone in late prepupal salivary glands of Drosophila melanogaster. » Cell Regulation 2, n^o 11 (novembre 1991) : 875–88. http://dx.doi.org/10.1091/mbc.2.11.875.

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DNA puffs occur in Sciarid salivary gland chromosomes; they are sites of DNA amplification and intense transcription and they appear to encode secreted structural proteins needed for pupation. In this report we have used P-element transformation of Drosophila to study regulation of a Sciara DNA puff gene. We found that a 718-bp promoter fragment of DNA puff gene II/9-1 from Sciara coprophila directs expression of the bacterial reporter gene CAT in late prepupal salivary glands of transgenic Drosophila melanogaster. The identical tissue and analogous stage specificity indicate that some aspects of the ecdysone response are evolutionarily conserved between Drosophila and Sciara. When transgenic salivary glands are cultured in vitro, CAT activity is rapidly induced by ecdysone, suggesting direct control of gene expression by the ecdysone receptor. Putative stage-specific factors limit expression of the chimeric Sciara-CAT gene in transgenic Drosophila to late prepupae but not to third instar larvae when ecdysone titers are also high.

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Roberts, Paul A., et Laune Ann MacPhail. « Structure and activity of salivary gland chromosomes of Drosophila gibberosa ». Chromosoma 92, n^o 1 (mai 1985) : 55–68. http://dx.doi.org/10.1007/bf00327245.

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Sorsa, Veikko. « Chromatin fibril size in salivary gland chromosomes of Drosophila melanogaster ». Hereditas 74, n^o 1 (12 février 2009) : 133–37. http://dx.doi.org/10.1111/j.1601-5223.1973.tb01111.x.

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Armstrong, Robin, Taylor Penke, Samuel Chao, Gabrielle Gentile, Brian Strahl, A. Matera, Daniel McKay et Robert Duronio. « H3K9 Promotes Under-Replication of Pericentromeric Heterochromatin in Drosophila Salivary Gland Polytene Chromosomes ». Genes 10, n^o 2 (29 janvier 2019) : 93. http://dx.doi.org/10.3390/genes10020093.

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Chromatin structure and its organization contributes to the proper regulation and timing of DNA replication. Yet, the precise mechanism by which chromatin contributes to DNA replication remains incompletely understood. This is particularly true for cell types that rely on polyploidization as a developmental strategy for growth and high biosynthetic capacity. During Drosophila larval development, cells of the salivary gland undergo endoreplication, repetitive rounds of DNA synthesis without intervening cell division, resulting in ploidy values of ~1350C. S phase of these endocycles displays a reproducible pattern of early and late replicating regions of the genome resulting from the activity of the same replication initiation factors that are used in diploid cells. However, unlike diploid cells, the latest replicating regions of polyploid salivary gland genomes, composed primarily of pericentric heterochromatic enriched in H3K9 methylation, are not replicated each endocycle, resulting in under-replicated domains with reduced ploidy. Here, we employ a histone gene replacement strategy in Drosophila to demonstrate that mutation of a histone residue important for heterochromatin organization and function (H3K9) but not mutation of a histone residue important for euchromatin function (H4K16), disrupts proper endoreplication in Drosophila salivary gland polyploid genomes thereby leading to DNA copy gain in pericentric heterochromatin. These findings reveal that H3K9 is necessary for normal levels of under-replication of pericentric heterochromatin and suggest that under-replication at pericentric heterochromatin is mediated through H3K9 methylation.

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Andres, A. J., et C. S. Thummel. « The Drosophila 63F early puff contains E63-1, an ecdysone-inducible gene that encodes a novel Ca(2+)-binding protein ». Development 121, n^o 8 (1 août 1995) : 2667–79. http://dx.doi.org/10.1242/dev.121.8.2667.

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Pulses of ecdysone at the end of Drosophila larval development dramatically reprogram gene expression as they signal the onset of metamorphosis. Ecdysone directly induces several early puffs in the salivary gland polytene chromosomes that, in turn, activate many late puffs. Three early puffs, at 2B5, 74EF, and 75B, have been studied at the molecular level. Each contains a single ecdysone primary-response gene that encodes a family of widely expressed transcription factors. We report here a molecular characterization of the 63F early puff. Unexpectedly, we have found this locus to be significantly different from the previously characterized early puff loci. First, the 63F puff contains a pair of ecdysone-inducible genes that are transcribed in the larval salivary glands: E63-1 and E63-2. Second, E63-1 induction in late third instar larvae appears to be highly tissue-specific, restricted to the salivary gland. Third, E63-1 encodes a novel Ca(2+)-binding protein related to calmodulin. The discovery of an ecdysone-inducible Ca(2+)-binding protein provides a foundation for integrating steroid hormone and calcium second messenger signaling pathways and generates an additional level for potential regulation of the ecdysone response.

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Brockhouse, C., J. A. B. Bass et N. A. Straus. « Chromocentre polymorphism in polytene chromosomes of Simulium costatum (Diptera : Simuliidae) ». Genome 32, n^o 4 (1 août 1989) : 510–15. http://dx.doi.org/10.1139/g89-476.

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The polytene chromosomes of the black fly species Simulium (Nevermannia) costatum are joined at the centromeres in a strongly heterochromatic chromocentre. Examination of the larval salivary gland chromosomes revealed two populations with a unique polymorphism for attachment to the chromocentre involving all centromeres. All three homologous pairs of chromosomes are polymorphic for centromeres that do not join to the chromocentre. Samples from one of these populations were large enough for thorough study. In this population, the attachment polymorphism is in Hardy-Weinberg equilibrium for two of the centromeres and was in the same frequency for 2 successive years of sampling. The polymorphism could be either primary, retained from an ancestral nonchromocentric state, or secondary, evolving independently or introduced via hybrid introgression. The evolution of chromocentres is discussed in the context of species in the Simulium vernum group.Key words: black fly, polytene chromosome, chromocentre, polymorphism, evolution.

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Pardali, E., E. Feggou, E. Drosopoulou, I. Konstantopoulou, Z. G. Scouras et P. Mavragani-Tsipidou. « The Afrotropical Drosophila montium subgroup : Balbiani ring 1, polytene chromosomes, and heat shock response of Drosophila vulcana ». Genome 39, n^o 3 (1 juin 1996) : 588–97. http://dx.doi.org/10.1139/g96-074.

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A detailed photographic map of the salivary gland polytene chromosomes of Drosophila vulcana, an Afrotropical species of the montium subgroup of the melanogaster group, is presented, along with chromosomal rearrangements, such as reverse tandem duplications and inversions, the well-formed Balbiani ring 1, and the most prominent puffs during normal larval and white prepupal development and after ecdysone treatment. In addition, the heat inducible protein and puffing pattern and the loci of the major heat shock genes, namely, hsp70, hsp83, the "small" hsps, and a putative hsp68, of this species were studied. In the light of the data revealed by the above studies, phylogenetic relationships among the montium subgroup species are attempted. Key words : Drosophila, Balbiani ring, polytene chromosomes, heat shock, puffs, genes, proteins, hsp70 single locus.

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Ruiz, Alfredo, José María Ranz, Mario Cáceres et Carmen Segarra. « Chromosomal evolution and comparative gene mapping in the Drosophila repleta species group ». Brazilian Journal of Genetics 20, n^o 4 (décembre 1997) : 553–65. http://dx.doi.org/10.1590/s0100-84551997000400003.

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A review of our recent work on the cromosomal evolution of the Drosophila repleta species group is presented. Most studies have focused on the buzzatii species complex, a monophyletic set of 12 species which inhabit the deserts of South America and the West Indies. A statistical analysis of the length and breakpoint distribution of the 86 paracentric inversions observed in this complex has shown that inversion length is a selected trait. Rare inversions are usually small while evolutionary successful inversions, fixed and polymorphic, are predominantly of medium size. There is also a negative correlation between length and number of inversions per species. Finally, the distribution of inversion breakpoints along chromosome 2 is non-random, with chromosomal regions which accumulate up to 8 breakpoints (putative "hot spots"). Comparative gene mapping has also been used to investigate the molecular organization and evolution of chromosomes. Using in situ hybridization, 26 genes have been precisely located on the salivary gland chromosomes of D. repleta and D. buzzatii; another nine have been tentatively identified. The results are fully consistent with the currently accepted chromosomal homologies between D. repleta and D. melanogaster, and no evidence for reciprocal translocations or pericentric inversions has been found. The comparison of the gene map of D. repleta chromosome 2 with that of the homologous chromosome 3R of D. melanogaster shows an extensive reorganization via paracentric inversions and allows to estimate an evolution rate of ~1 inversion fixed per million years for this chromosome

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Eggleston, William B., Nac R. Rim et Johng K. Lim. « Molecular Characterization of hobo-Mediated Inversions in Drosophila melanogaster ». Genetics 144, n^o 2 (1 octobre 1996) : 647–56. http://dx.doi.org/10.1093/genetics/144.2.647.

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Abstract The structure of chromosomal inversions mediated by hobo transposable elements in the Uc-1 X chromosome was investigated using cytogenetic and molecular methods. Uc-1 contains a phenotypically silent hobo element inserted in an intron of the Notch locus. Cytological screening identified six independent Notch mutations resulting from chromosomal inversions with one breakpoint at cytological position 3C7, the location of Notch. In situ hybridization to salivary gland polytene chromosomes determined that both ends of each inversion contained hobo and Notch sequences. Southern blot analyses showed that both breakpoints in each inversion had hobo-Notch junction fragments indistinguishable in structure from those present in the Uc-1 X chromosome prior to the rearrangements. Polymerase chain reaction amplification of the 12 hobo-Notch junction fragments in the six inversions, followed by DNA sequence analysis, determined that each was identical to one of the two hobo-Notch junctions present in Uc-1. These results are consistent with a model in which hobo-mediated inversions result from homologous pairing and recombination between a pair of hobo elements in reverse orientation.

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Hurban, P., et C. S. Thummel. « Isolation and characterization of fifteen ecdysone-inducible Drosophila genes reveal unexpected complexities in ecdysone regulation ». Molecular and Cellular Biology 13, n^o 11 (novembre 1993) : 7101–11. http://dx.doi.org/10.1128/mcb.13.11.7101-7111.1993.

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Our insights into the regulatory mechanisms by which the steroid hormone ecdysone triggers Drosophila melanogaster metamorphosis have largely depended on puffs in the larval salivary gland polytene chromosomes as a means of identifying genes of interest. Here, we describe an approach that provides access to ecdysone-inducible genes that are expressed in most larval and imaginal tissues, regardless of their ability to form puffs in the polytene chromosomes. Several hundred cDNAs were picked at random from subtracted cDNA libraries and subjected to a rapid and sensitive screen for their ability to detect mRNAs induced by ecdysone in the presence of cycloheximide. Of the 15 genes identified in this manner, 2 correspond to early puffs in the salivary gland polytene chromosomes, at 63F and 75B, confirming that this screen functions at the desired level of sensitivity and is capable of identifying novel primary-response genes. Three of the genes, Eig45-1, Eig58, and Eig87, are expressed coordinately with the salivary gland early genes; one of them, Eig58, maps to the 58BC puff that is active when the 74EF and 75B early puffs are at their maximal size. Another gene identified in this screen, Eig17-1, encodes a novel cytochrome P-450. On the basis of its sequence identity and temporal profile of expression, this gene may play a role in steroid hormone metabolism and thus could provide a mechanism for feedback regulation of ecdysone production. Although all 15 genes have patterns of transcription that are consistent with ecdysone regulation in vivo, 5 genes do not appear to be induced by the late larval ecdysone pulse. This indicates that ecdysone induction in larval organs cultured with cycloheximide is not always indicative of a primary response to the hormone.

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Hurban, P., et C. S. Thummel. « Isolation and characterization of fifteen ecdysone-inducible Drosophila genes reveal unexpected complexities in ecdysone regulation. » Molecular and Cellular Biology 13, n^o 11 (novembre 1993) : 7101–11. http://dx.doi.org/10.1128/mcb.13.11.7101.

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Our insights into the regulatory mechanisms by which the steroid hormone ecdysone triggers Drosophila melanogaster metamorphosis have largely depended on puffs in the larval salivary gland polytene chromosomes as a means of identifying genes of interest. Here, we describe an approach that provides access to ecdysone-inducible genes that are expressed in most larval and imaginal tissues, regardless of their ability to form puffs in the polytene chromosomes. Several hundred cDNAs were picked at random from subtracted cDNA libraries and subjected to a rapid and sensitive screen for their ability to detect mRNAs induced by ecdysone in the presence of cycloheximide. Of the 15 genes identified in this manner, 2 correspond to early puffs in the salivary gland polytene chromosomes, at 63F and 75B, confirming that this screen functions at the desired level of sensitivity and is capable of identifying novel primary-response genes. Three of the genes, Eig45-1, Eig58, and Eig87, are expressed coordinately with the salivary gland early genes; one of them, Eig58, maps to the 58BC puff that is active when the 74EF and 75B early puffs are at their maximal size. Another gene identified in this screen, Eig17-1, encodes a novel cytochrome P-450. On the basis of its sequence identity and temporal profile of expression, this gene may play a role in steroid hormone metabolism and thus could provide a mechanism for feedback regulation of ecdysone production. Although all 15 genes have patterns of transcription that are consistent with ecdysone regulation in vivo, 5 genes do not appear to be induced by the late larval ecdysone pulse. This indicates that ecdysone induction in larval organs cultured with cycloheximide is not always indicative of a primary response to the hormone.

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SORSA, VEIKKO, et VIRPI VIRRANKOSKI-CASTRODEZA. « H3-thymidine radioautography of salivary gland chromosomes treated with alkali-urea ». Hereditas 71, n^o 1 (12 février 2009) : 139–44. http://dx.doi.org/10.1111/j.1601-5223.1972.tb01011.x.

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Kaiser, P. E., J. A. Seawright et B. K. Birky. « Chromosome polymorphism in natural populations of Anopheles quadrimaculatus Say species A and B ». Genome 30, n^o 2 (1 avril 1988) : 138–46. http://dx.doi.org/10.1139/g88-024.

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Ovarian polytene chromosomes from eight populations of Anopheles quadrimaculatus in the southeastern United States were observed for chromosomal polymorphisms. Two sibling species, species A and B, each with intraspecific inversions, were distinguished. Species A correlates with the previously published standard maps for salivary gland and ovarian nurse-cell polytene chromosomes. Species A was found at all eight collection sites, and five of these populations also contained species B. Three inversions on the right arm of chromosome 3 were observed in species A. Species B contained a fixed inversion on the X chromosome, one fixed and one floating inversion on the left arm of chromosome 2, and one fixed and one floating inversion on the right arm of chromosome 3. The fixed inversion on the X chromosome makes this the best diagnostic chromosome for distinguishing species A and B. An unusual dimorphism in the left arm of chromosome 3, found in both species A and B, contained two inversions. The heterokaryotypes, as well as two distinct homokaryotypes, were seen in all of the field populations. Intraspecific clinal variations in the frequencies of the species A inversions were noted. The Florida populations were practically devoid of inversions, the Georgia and Alabama populations contained some inversions, and the Arkansas population was mostly homozygous for two of the inversions. The phylogenetic relationships of species A and B to the Maculipennis complex (Nearctic) are discussed.Key words: Anopheles, inversion, populations, chromosome polymorphism, phylogenetics.

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Vaskova, Martina, A. M. Bentley, Samantha Marshall, Pamela Reid, Carl S. Thummel et Andrew J. Andres. « Genetic Analysis of the Drosophila 63F Early Puff : Characterization of Mutations in E63-1 and maggie, a Putative Tom22 ». Genetics 156, n^o 1 (1 septembre 2000) : 229–44. http://dx.doi.org/10.1093/genetics/156.1.229.

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Abstract The 63F early puff in the larval salivary gland polytene chromosomes contains the divergently transcribed E63-1 and E63-2 ecdysone-inducible genes. E63-1 encodes a member of the EF-hand family of Ca2+-binding proteins, while E63-2 has no apparent open reading frame. To understand the functions of the E63 genes, we have determined the temporal and spatial patterns of E63-1 protein expression, as well as undertaken a genetic analysis of the 63F puff. We show that E63-1 is expressed in many embryonic and larval tissues, but the third-instar larval salivary gland is the only tissue where increases in protein levels correlate with increases in ecdysone titer. Furthermore, the subcellular distribution of E63-1 protein changes dynamically in the salivary glands at the onset of metamorphosis. E63-1 and E63-2 null mutations, however, have no effect on development or fertility. We have characterized 40 kb of the 63F region, defined as the interval between Ubi-p and E63-2, and have identified three lethal complementation groups that correspond to the dSc-2, ida, and mge genes. We show that mge mutations lead to first-instar larval lethality and that Mge protein is similar to the Tom22 mitochondrial import proteins of fungi, suggesting that it has a role in mitochondrial function.

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Locke, John, Lynn Podemski, Nicole Aippersbach, Hilary Kemp et Ross Hodgetts. « A Physical Map of the Polytenized Region (101EF–102F) of Chromosome 4 in Drosophila melanogaster ». Genetics 155, n^o 3 (1 juillet 2000) : 1175–83. http://dx.doi.org/10.1093/genetics/155.3.1175.

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Abstract Chromosome 4, the smallest autosome (~5 Mb in length) in Drosophila melanogaster contains two major regions. The centromeric domain (~4 Mb) is heterochromatic and consists primarily of short, satellite repeats. The remaining ~1.2 Mb, which constitutes the banded region (101E–102F) on salivary gland polytene chromosomes and contains the identified genes, is the region mapped in this study. Chromosome walking was hindered by the abundance of moderately repeated sequences dispersed along the chromosome, so we used many entry points to recover overlapping cosmid and BAC clones. In situ hybridization of probes from the two ends of the map to polytene chromosomes confirmed that the cloned region had spanned the 101E–102F interval. Our BAC clones comprised three contigs; one gap was positioned distally in 102EF and the other was located proximally at 102B. Twenty-three genes, representing about half of our revised estimate of the total number of genes on chromosome 4, were positioned on the BAC contigs. A minimal tiling set of the clones we have mapped will facilitate both the assembly of the DNA sequence of the chromosome and a functional analysis of its genes.

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Shakina, Lyubov, Vladimir Pasiuga, Olexandr Dumin et Yuriy Shckorbatov. « Effects of microwaves on the puffing pattern of D. melanogaster ». Open Life Sciences 6, n^o 4 (1 août 2011) : 524–30. http://dx.doi.org/10.2478/s11535-011-0032-x.

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AbstractThe influence of electromagnetic field exposure on puffing pattern of salivary gland polythene chromosomes, viability and fertility of Drosophila melanogaster of the wild type Canton-S line was studied. Experimental conditions: Electromagnetic field characteristics: frequency — 36.64 GHz, power density — 0.4 W/m2, exposure time −10 seconds. Electromagnetic field exposure was conducted on the egg stage. Results: in larvae developed from the exposed eggs 3 of 8 chromosomal puffs tested (71CE, 82EF, and 83E) had significantly smaller dimensions than these in control at the prepupal stage. Viability of Drosophila estimated by the number of adult flies hatched from exposed eggs decreased, while the number of dominant lethal mutations increased. Conclusion: the exposure to a low-level microwave irradiation suppressed puffing activity at ecdysone-inducible loci of Drosophila polythene chromosomes, increased frequency of dominant lethal mutations and decreased Drosophila viability but did not influence Drosophila fertility.

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