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  • 1
    ISSN: 1439-0361
    Schlagwort(e): Biogeography ; geographic variation ; taxonomy ; Amazilia ; Trochilidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die vorliegende Studie stellt die Ergebnisse von Untersuchungen zur Biogeographie, geographischen Variation, Habitatwahl und Taxonomie der Lesson-Amazilie (Amazilia amazilia) vor. Das Taxon umfaßt gegenwärtig fünf Unterarten, die von W-Ecuador bis SW-Peru verbreitet sind und überwiegend submontane Lebensräume besiedeln. Die Ventralfärbung unterliegt klinaler Variation; weiße Gefiederanteile nehmen von nördlichen zu südlichen Populationen ab, rotbraune Partien dagegen zu. Eigenständige morphologisch-morphometrische Kennzeichen sowie Unterschiede in den Habitatpräferenzen und in der Gesangsstruktur rechtfertigen es, die bisherige UnterartA. a. alticola als Paraspezies (A. alticola, Loja-Amazilie) anzuerkennen. Der Vulgärname weist auf den rezenten Verbreitungsschwerpunkt in den südecuadorianischen Anden hin. Aufgrund der engen Verwandtschaft bildenA. amazilia undA. alticola sowie die in Kolumbien endemische ArtA. castaneiventris eine Superspezies.
    Notizen: Summary This paper reviews the biogeography, geographic variation, and habitat characteristics of the Amazilia Hummingbird (Amazilia amazilia). Based on morphological features, habitat preferences, and bioacoustics, I propose that the currently recognized subspeciesA. a. alticola should be regarded as a species distinct fromA. amazilia. Synapomorphic characters found in both taxa indicate membership of the same superspecies, together with the Colombian speciesA. castaneiventris. Considering the distributional focus ofA. alticola in the Andes of southern Ecuador, the English species name Loja Hummingbird is suggested.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of ornithology 141 (2000), S. 275-284 
    ISSN: 1439-0361
    Schlagwort(e): East Asia ; taxonomy ; species delimitation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Über die Gliederung der ostasiatischen Dickschnabelkrähen (Corvus macrorhynchos s.l.) in Biospezies besteht bisher keine einhellige Meinung. In dem großen Verbreitungsgebiet zwischen Indien, Japan und Timor werden gegenwärtig eine, zwei oder drei Arten anerkannt. Hier versuchen wir, in akustischen Merkmalen artanzeigende Merkmale zu finden. Eine Diskriminanzanalyse der Rufstruktur (76 Parameter) trennt dreiCorvus-Taxa (levaillantii undjaponensis aus der ‘macrorhynchos-Gruppe’,splendens) von der Südabdachung des Himalaya (Nepal, Kashmir) vollständig voneinander. BeiC. japonensis bleiben die trennenden Merkmale über große geographische Gebiete konstant. Die akustischen Unterschiede werden als taxonomisch relevant angesehen; sie zeigen Artgrenzen an. Folglich werden die Dickschnabelkrähen aus den Tief- und Hochlagen Nepals (Kontaktzone um 2 000 m) zwei Biospezies zugeordnet (C. japonensis undC. levaillantii), in Übereinstimmung mit morphologischen, ökologischen und parasitologischen Daten. Taxonomische Extrapolation der Befunde auf die Systematik anderer ‘macrorhynchos’-Populationen erscheint über die Rufstruktur (bis zum Fernen Osten Rußlands) und über Federling-Parasiten (Mallophaga) auf große Teile SO-Asiens möglich, bedarf aber für die stimmlichen Merkmale noch weiterer Klärung. Wahrscheinlich müssen immacrorhynchos-Komplex mindestens drei biologische Arten anerkannt werden (C. japonensis, C. levaillantii, C. macrorhynchos s. str.).
    Notizen: Summary A discriminant analysis of the call structure completely separates threeCorvus taxa (levaillantii andjaponensis of the ‘macrorhynchos group’,splendens) inhabiting the southern slopes of the Himalayas (Nepal, Kashmir). The acoustic differences are considered taxonomically relevant, indicating species boundaries. Therefore the Jungle Crows of lower and upper Nepal (contact zone at around 2,000 m) are assigned to two biospecies (C. japonensis andC. levaillantii), as is consistent with morphological, ecological and parasitological data. It appears possible to extrapolate the findings regarding call structure to the systematics of other ‘macrorhynchos’ populations as distant as the Russian Far East, and those regarding mallophagan parasites to large areas of SE Asia; regarding the vocal characteristics, however, further clarification is needed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 94 (2000), S. 159-171 
    ISSN: 1570-7458
    Schlagwort(e): Drosophila ; induction ; habituation ; associative learning ; T-maze olfactometer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Experiments reported in this paper investigate the properties of a change in the responsiveness of adult Drosophila melanogaster induced by exposure to different rearing media. This effect has previously been described as habituation or associative learning. Exposure to food medium containing 0.08% menthol induced a positive response to menthol odour in a T-maze olfactometer. A brief (one hour) exposure to mentholic food just before testing was sufficient to induce a change in responsiveness. The effect did not persist through periods of more than an hour of separation from mentholic medium. Effects induced by exposure to a single compound were not specific to that compound alone. Menthol-reared flies (MRFs) differed from plain reared flies (PRFs) in their responsiveness to the odours of benzaldehyde and ethyl acetate, as well as menthol, and exposure to ethyl acetate induced a change in response to menthol odour. That there was an induced positive response to menthol in MRFs suggests that conventional habituation is insufficient to explain the induced change in responsiveness, but the generalised nature of this behavioural induction in MRFs is hard to explain in terms of associative learning. The mechanism underlying the induction remains elusive.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1572-8889
    Schlagwort(e): courtship song ; wingbeat ; sexual isolation ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of insect behavior 13 (2000), S. 361-373 
    ISSN: 1572-8889
    Schlagwort(e): Drosophila ; copulatory courtship ; mate choice ; cryptic female choice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two endemic Australian Drosophila species, D. birchii and D. serrata, have a copulatory courtship, i.e., the males court the female mainly during copulation. In the present study we found the males of both species to mount their prospective mating partners selectively, exhibiting both sex and species recognition. The males began to sing after mounting the female, and they often exhibited also postcopulatory displays typical to copulatory courtship. D. birchii and D. serrata females discriminated against males which did not sing during mounting/copulation, which suggests that the females utilize cryptic female choice. Our findings raise the question of how widespread a phenomenon cryptic female choice is in Drosophila species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 18 (1982), S. 310-314 
    ISSN: 1432-1432
    Schlagwort(e): Neutral mutation theory ; Natural selection ; Protein evolution ; Levene model ; Environmental variability ; Genetic variability ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary If a phenotypic character is under stabilizing selection, the selective disadvantage of a nonoptimal genotype will decrease exponentially to zero as the proportion of phenotypic variation that is environmental in origin -V e /V p - increases. Under the modified mutation-drift hypothesis of genetic polymorphism, the proportion of mutations that are effectively neutral and average heterozygosity should increase with this ratio. Invertebrates, because of their small size, fast development, and low degree of homeostasis (relative to vertebrates), are expected to show a larger environmental component of phenotypic variation than vertebrates. This may help explain why invertebrates are in general more genetically variable than vertebrates and why, when laboratory populations ofDrosophila are maintained in heterogeneous environments, genetic variability is lost less rapidly than when they are kept in constant conditions.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 16 (1980), S. 37-46 
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Drosophila ; Temperature ; Mitochondrial enzymes ; Kinetic properties
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The evolutionary behavior of two mitochondrial enzymes (L-glycerol 3-phosphate:cytochrome c oxidoreductase E.C.1.1.1.95,αGPO, and L-malate: NAD+ oxidoreductase, E.C.1.1.1.37, m-MDH) obtained from several temperate and tropicalDrosophila species was examined by comparing their catalytic properties, which related to temperature (Km-Ea-Q10-Thermostability). MitochondrialαGPO or m-MDH obtained either from temperate or from tropical species was found to exhibit similar catalytic properties while for both cytosolic enzymes, theαGPDH and s-MDH, Km patterns were similar among species from the same thermal habitat and different between thermal habitats. In combination with other observations reported in the literature these facts support the view that the function, and probably the structure, of mitochondrial enzymes are better conserved in evolution than those of the corresponding enzymes found in the cytosol. It is proposed that the relative invariance of the mitochondrial enzymes structure is probably linked to a necessary relative invariance of molecular interactions inside the mitochondrion.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 20 (1984), S. 251-264 
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Genome evolution ; 68C Glue gene cluster ; Drosophila melanogaster species subgroup
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The 68C puff is a highly transcribed region of theDrosophila melanogaster salivary gland polytene chromosomes. Three different classes of messenger RNA originate in a 5000-bp region in the puff; each class is translated to one of the salivary gland glue proteins sgs-3, sgs-7, or sgs-8. These messenger RNA classes are coordinately controlled, with each RNA appearing in the third larval instar and disappearing at the time of puparium formation. Their disappearance is initiated by the action of the steroid hormone ecdysterone. In the work reported here, we studied evolution of this hormone-regulated gene cluster in themelanogaster species subgroup ofDrosophila. Genome blot hybridization experiments showed that five other species of this subgroup have DNA sequences that hybridize toD. melanogaster 68C sequences, and that these sequences are divided into a highly conserved region, which does not contain the glue genes, and an extraordinarily diverged region, which does. Molecular cloning of this DNA fromD. simulans, D. erecta, D. yakuba, andD. teissieri confirmed the division of the region into a slowly and a rapidly evolving protion, and also showed that the rapidly evolving region of each species codes for third instar larval salivary gland RNAs homologous to theD. melanogaster glue mRNAs. The highly conserved region is at least 13,000 bp long, and is not known to code for any RNAs.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Conservation genetics 1 (2000), S. 67-76 
    ISSN: 1572-9737
    Schlagwort(e): mitochondrial DNA ; phylogeny ; phylogeography ; speciation ; species concepts ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of the history of biology 33 (2000), S. 27-70 
    ISSN: 1573-0387
    Schlagwort(e): ants ; E. O. Wilson ; Ernst Mayr ; systematics ; Systematics and the Origin of Species ; taxonomy ; William L. Brown ; William Morton Wheeler ; William Steel Creighton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geschichte
    Notizen: Abstract Ideas about the natural world are intertwined with the personalities, practices, and the workplaces of scientists. The relationships between these categories are explored in the life of the taxonomist William Steel Creighton. Creighton studied taxonomy under William Morton Wheeler at Harvard University. He took the rules he learned from Wheeler out of the museum and into the field. In testing the rules against a new situation, Creighton found them wanting. He sought a new set of taxonomic principles, one he eventually found in Ernst Mayr's Systematics and the Origin of Species. Mayr's ideas tied together a number of themes running through Creighton's life: the need for a revised taxonomy, the emphasis on fieldwork, and the search for a new power center for ant taxonomy after Wheeler died. Creighton's adoption of Mayr's ideas as part of his professional identity also had very real implications for his career path: field studies required long and intensive studies, and Creighton would always be a slow worker. His method of taxonomy contrasted sharply not only with Wheeler's but also with two of his younger colleagues, William L. Brown and E. O. Wilson, who took over Wheeler's spot at Harvard in 1950. The disputes between these men over ant taxonomy involved, in addition to questions of technical interest, questions about where and how best to do taxonomy and who could speak withthe most authority. Creighton's story reveals how these questions are interrelated. The story also reveals the importance of Mayr's book for changes occurring in taxonomy in the middle of the twentieth century.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 188 (1980), S. 55-63 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Compound eye ; shibire ts ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have analysed the effect of temperature on both developing and adult eye cell clones homozygous forshi ST139, a temperature-sensitive mutant ofDrosophila melanogaster. The mutant gene, autonomous in its cellular expression, causes structural modifications of ommatidial cells when adult clones of cells are exposed to the restrictive temperature (29°C) for several days. However, the mutant phenotype reverses to normal within 4 days at the permissive temperature (20°C). The results of pulse, shift-up and shift-down experiments show that the temperaturesensitive period for developing compound eye cells is from the late second instar up to the early pupa. Cytodifferentiation of compound eye cells is blocked by restrictive temperature treatment during this period, whereas cell proliferation does not seem to be directly affected. These results are discussed with regard to the other known aspects of the phenotype observed in mutant individuals.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 164-170 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The early morphogenesis of the eye-antennal disc ofDrosophila in response to 20-hydroxy ecdysone involves the curling of the eye anlagen dorsally over the antenna. During this process, the area of the peripodial membrane is substantially reduced. The peripodial membrane is taut at this stage, and if it is cut the curling of the disc cannot continue, and the eye anlagen returns to its original position within one minute of the operation. In contrast, cutting the columnar epithelium between the eye and antennal anlagen does not disrupt curling, but actually facilitates it. During curling, the cells of the peripodial membrane appear healthy, and exhibit basal extensions. We suggest that the curling of the eye is mediated by the conversion of cuboidal peripodial membrane cells into pseudostratified columnar epithelium at the edges of the peripodial membrane. Subsequently, cells of the peripodial membrane secrete first a pupal cuticle, and then an imaginal cuticle.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 275-279 
    ISSN: 1432-041X
    Schlagwort(e): Evagination ; Morphogenesis ; Metamorphosis ; Female genital disc ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The morphology of the evaginating female genital disc ofDrosophila melanogaster was examined at different stages of metamorphosis. The observations show that the internal genital organs are derived from the anterior half of the disc and that their morphogenesis is mainly a protrusion of the different primordial areas of the disc epithelium. The external genital and anal derivatives originate from the posterior half of the disc, which undergoes complex rearrangements during metamorphosis. The disc opens along the posterior margin and the dorsal and ventral epithelia evert and thereby completely reverse their anteroposterior orientation. Dramatic elongation has been observed during the formation of the seminal receptacle. The cells of the repressed male genital primordium do not form any recognizable structures and are assumed to be eliminated during metamorphosis.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 299-302 
    ISSN: 1432-041X
    Schlagwort(e): Differentiation ; Teratogens ; Drosophila ; 5-Azacytidine ; Methylation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The effects of cytidine and cytidine analogs were studied inDrosophila embryonic cell cultures and two wild-type established cell lines, Oregon-R and Schneider line 2. Primary embryonic cultures have been shown to be an excellent system for the study of embryonic development; a number of cell types undergo normal differentiation in vitro. Treatment of these cultures with putative teratogens resulted in an inhibition of muscle and/or neuron differentiation in our study. Treatment of these cells with cytidine and seven other analogs had no effect on neuron and muscle differentiation. The compound 5-azacytidine, when added to primary cell cultures, inhibited normal differentiation at subtoxic doses while inducing the production of three proteins that comigrate with the heat-shock proteins, hsp 23, 22a and 22b. 5-Azacytidine did not stimulate differentiation in Oregon-R or SchneiderDrosophila cell lines. The in vitro blockage of differentiation by 5-azacytidine suggests that it may act as a teratogen.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 267-282 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In a search for embryonic lethal mutants on the second chromosome ofDrosophila melanogaster, 5764 balanced lines isogenic for an ethyl methane sulfonate (EMS)-treatedcn bw sp chromosome were established. Of these lines, 4217 carried one or more newly induced lethal mutations corresponding to a total of 7600 lethal hits. Eggs were collected from lethal-bearing lines and unhatched embryos from the lines in which 25% or more of the embryos did not hatch (2843 lines) were dechorionated, fixed, cleared and scored under the compound microscope for abnormalities of the larval cuticle. A total of 272 mutants were isolated with phenotypes unequivocally distinguishable from wild-type embryos on the basis of the cuticular pattern. In complementation tests performed between mutants with similar phenotype, 48 loci were identified by more than one allele, the average being 5.4 alleles per locus. Complementation of all other mutants was shown by 13 mutants. Members of the complementation groups were mapped by recombination analysis. No clustering of loci with similar phenotypes was apparent. From the distribution of the allele frequencies and the rate of discovery of new loci, it was estimated that the 61 loci represent the majority of embryonic lethal loci on the second chromosome yielding phenotypes recognizable in the larval cuticle.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 90-97 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Temperature-sensitive ; Neoplasms ; Differentiation ; Imaginal discs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary EMS induced temperature-sensitivelethal (2) giant larva, 1(2)gl, alleles were isolated by screening against a knownl(2)gl allele. Analysis of the lethal phase of thel(2)gl ts-deficiency heterozygotes demonstrated: (1) the majority of thel(2)gl tslarvae survive to late third instar, (2) at 29°C the majority of thel(2)gl tslarvae failed to pupate and only rarely did they differentiate adult cuticular structures, (3) at 15°C the majority of the larvae pupated and frequently differentiated adult cuticular structures. Examination of the imaginal discs ofl(2)gl tslarvae reared at 29°C revealed the presence of morphologically abnormal wing, haltere and leg imaginal discs. No morphologically abnormal discs were found in thel(2)gl tslarvae reared at 15°C. Studies on both the histology and the developmental capacity of the morphologically normal and abnormall(2)gl tsdiscs were performed. The morphologically normal discs are histologically normal and produce a full complement of adult cuticular structures. However, the morphologically abnormal discs contained both regions that maintained the normal monolayer epithelium and regions that had lost the normal tissue architecture. The implants obtained when the morphologically abnormal discs are injected into metamorphosing larvae contained only a limited number of the normal complement of adult structures and usually only structures found in the ventral wing hinge region were recovered. In addition, the “metamorphosed” morphologically abnormal discs contained undifferentiated tissue that gave rise to transplantable neoplasms when cultured in adults. The results of the studies on the pathology of thel(2)gl tslarvae are discussed with respect to the role of thel(2)gl tsfunction during normal development, the autonomy of the neoplastic development of thel(2)gl tstissues, and similarities between neoplastic development inDrosophila and mammals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 194 (1984), S. 99-106 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Pole cell transplantation ; Heterospecific combinations ; Gametogenesis ; Chorion morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We transplanted pole cells betweenDrosophila melanogaster, D. mauritiana andD. ananassae to investigate the ability of germ cells to develop in the gonad of a heterospecific host, and to study the interaction between somatic follicle cells and the cells of the germ line in producing the species-specific chorion. FemaleD. mauritiana germ cells in aD. melanogaster ovary produced functional eggs with normal development potential. The same is true for the reciprocal combination. FemaleD. ananassae pole cells in aD. melanogaster host only developed to a very early stage and degenerated afterwards. None of the interspecific combinations of male pole cells led to functional sperm. We could not determine at what stage the transplanted male pole cells were arrested. The cooperation of follicle cells and the oocyte-nurse cell complex in producing the chorion was studied using the germ-line-dependent mutationfs(1) K10 ofD. melanogaster, which causes fused respiratory appendages and an abnormal chorion morphology. Wild-type femaleD. mauritiana germ cells in a mutantfs(1) K10 D. melanogaster ovary led to the production of wild-type eggs withD. melanogaster-specific, short respiratory appendages. On the other hand,D. melanogaster fs(1) K10 germ cells in aD. mauritiana ovary induced the formation of eggs with mutant fused appendages which were, however, typicallyD. mauritiana in length. When.D. mauritiana pole cells developed in aD. melanogaster ovary, the chorion exhibited a new imprint pattern that differs from both species-specific patterns.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 118-122 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Aggregation ; Lectins ; Cell surface ; Embryo-derived cell line
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In this paper we describe the aggregation of cells from embryo-derived cell lines ofDrosophila, measured by examining the ability of single cells to adhere to one another when suspended in culture medium and swirled on a rotary shaker. Using this method we demonstrated the presence of receptors for Concanavalin A, soybean agglutinin, and possibly wheat germ agglutinin on the surface of Schneider's line-2 cells. Our work provides basic descriptive and background information for further studies onDrosophila cells, including those isolated from imaginal discs.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 297-300 
    ISSN: 1432-041X
    Schlagwort(e): Myosins ; Drosophila ; muscle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Electrophoresis of myosin extracts from larvae and adult tissues ofDrosophila melanogaster under non-dissociating conditions indicate that two of the bands seen are myosins. They stain for Ca2+ ATPase activity and when cut and re-run under dissociating conditions are found to contain a myosin heavy chain that co-migrates with rabbit skeletal muscle myosin heavy chain. One of the forms of myosin seen is found primarily in extracts from the leg. The other is common to the adult fibrillar flight muscles and the larval body wall muscles. The electrophoretic evidence for two myosin types is strengthened by the histochemical demonstration of two myofibrillar ATPases on the basis of their lability to acid or alkali preincubation. The myofibrillar ATPase in the leg and the Tergal Depressor of the Trochanter (TDT) are shown to be relatively acid labile and alkali stable. The larval body wall muscles and the adult fibrillar flight muscles have an ATPase which is acid stable and alkali labile. This distribution of the two myofibrillar ATPase coincides with that predicted by electrophoresis of extracts from whole tissue and also locates the two myosins to specific muscle types.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1432-041X
    Schlagwort(e): Key words Brain development ; Axonal scaffold ; Extradenticle ; Homothorax ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  During early brain development in Drosophila a highly stereotyped pattern of axonal scaffolds evolves by precise pioneering and selective fasciculation of neural fibers in the newly formed brain neuromeres. Using an axonal marker, Fasciclin II, we show that the activities of the extradenticle (exd) and homothorax (hth) genes are essential to this axonal patterning in the embryonic brain. Both genes are expressed in the developing brain neurons, including many of the tract founder cluster cells. Consistent with their expression profiles, mutations of exd and hth strongly perturb the primary axonal scaffolds. Furthermore, we show that mutations of exd and hth result in profound patterning defects of the developing brain at the molecular level including stimulation of the orthodenticle gene and suppression of the empty spiracles and cervical homeotic genes. In addition, expression of a Drosophila Pax6 gene, eyeless, is significantly suppressed in the mutants except for the most anterior region. These results reveal that, in addition to their homeotic regulatory functions in trunk development, exd and hth have important roles in patterning the developing brain through coordinately regulating various nuclear regulatory genes, and imply molecular commonalities between the developmental mechanisms of the brain and trunk segments, which were conventionally considered to be largely independent.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 210 (2000), S. 157-161 
    ISSN: 1432-041X
    Schlagwort(e): Key words Swallow ; bicoid ; Drosophila ; mRNA localization ; Oogenesis ; Embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We analyzed a functional homologue of the swallow gene from Drosophila pseudoobscura. The swallow gene of D. melanogaster plays an essential role in localizing bicoid mRNA in oocytes, and swallow mutant embryos show anterior pattern defects that result from the lack of localization of the bicoid morphogen. The pseudoobscura homologue rescues the function of swallow mutants when introduced into the genome of D. melanogaster, and its expression is similar to that of the melanogaster gene. The predicted pseudoobscura and melanogaster proteins are 49% identical and 69% conserved. The coiled-coil domain previously identified in the melanogaster swallow protein is strongly conserved in the pseudoobscura homologue, but the weak similarity of the melanogaster swallow protein to the RNP class of RNA-binding proteins is not conserved in the pseudoobscura homologue. These and other observations suggest a structural role for swallow in localizing bicoid mRNA, perhaps as part of the egg cytoskeleton.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 185-190 
    ISSN: 1432-041X
    Schlagwort(e): Wound healing ; Regeneration ; Imaginal discs ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary When complementary fragments of an imaginal disc ofDrosophila are cultured for several days prior to metamorphosis, usually one fragment will regenerate while the other will duplicate. It has been proposed that wound healing plays an important part in disc regulation (French et al. 1976; Reinhardt et al. 1977) by initiating cell proliferation and determining the mode of regulation. We tried to delay the wound healing process by leaving a region of dead cells between the wound edges. In “06” fragments (Bryant 1975a) wound healing has occurred after 1–2 days of culture and the regeneration of missing structures after 2–4 days of culture. We observed that leaving a region of dead cells between the wound edges delays both wound healing and the regeneration of missing structures by 2 days. When disc fragments are cultured in female abdomens and then exposed to3H-thymidine to label replicating cells, then the label is found to be localised around the wound. We observed that delaying wound healing does not delay this localisation of labelled nuclei indicating that wound healing may not be required to initiate DNA replication.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 156-160 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Transdetermination ; Homeosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The transdetermination capacities of leg discs ofDrosophila melanogaster were examined by mechanically disrupting and kneading whole discs from late third instar larvae and by culturing the resulting tissue mass for 10–14 days in adult female abdomens where the cells continued to divide. The grown implants were then dissected from the abdomens and injected into third instar larvae to undergo metamorphosis. After this treatment, prothoracic leg discs ofDrosophila melanogaster transdetermined with a high frequency (59% of all implants) to wing. Mesothoracic leg discs also transdetermined to wing, but at a very low frequency (4%). Metathoracic leg discs exhibited the same low frequency of transdetermination (4%), but in this case the direction of transdetermination was to haltere (Table 1,D. melanogaster). Very similar results were obtained with leg discs ofDrosophila nigromelanica (Table 1,D. nigromelanica), showing that the peculiar behavior of the three leg discs is not unique forDrosophila melanogaster. The homeotic mutation Polycomb (Pc 3) which partially transforms meso- and metathoracic legs into prothoracic legs did not significantly increase the frequencies of transdetermination in these leg dises and had clearly no effect on the direction of transdetermination (Table 1).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 285-288 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; homoeosis ; Compartments ; Aldehyde oxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The aldehyde oxidase staining pattern in wing discs ofDrosophila melanogaster bearing the genotypesap blt /ap blt andap blt andap blt /ap 73n showns changes from the wild-type pattern. Extensive areas of the presumptive dorsal posterior wing blade, which are normally unstained, have enzyme activity in these mutants. In wings of these genotypes, dorsal posterior structures are replaced by dorsal anterior wing structures. A strong correlation has been found between the frequencies of various staining patterns in the discs and the extent of transformation in the cuticular structures of the wing, which is consistent with the idea that aldehyde oxidase activity can be used as an indicator in the wing disc of this transformation. Unlike the homoeotic mutationengrailed, apterous has not been interpreted as a selector gene yet the work reported here shows thatapterous alleles can cause changes resembling those of theengrailed phenotype both in aldehyde oxidase staining behaviour and in the cuticular transformation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 264-269 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Sexcombless ; Foreleg basitarsus ; Genital disc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The chromosome which carries the mutationsexcombless (In(1)sx) affects males and females ofD. melanogaster. In the male foreleg basitarsi the number of sexcomb teeth is dramatically reduced from 10 to 0.7 and the number of transverse rows of bristles is increased from 6 to 8. Females homozygous forIn(1)sx show a normal bristle pattern in the foreleg basitarsus. The genital disc derivatives of both male and femaleIn(1)sx flies are strongly affected. While the external genitalia show a duplicated or a reduced bristle pattern, the internal genitalia are mostly absent. However, the sexually dimorphic tergites and sternites of the abdomen remain unaffected. The male-specific effect on the basitarsus and the general effects on the genital disc derivatives are proposed to represent two different phenotypic effects ofIn(1)sx which may derive from mutations at different gene loci in the inverted chromosome.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 289-291 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Cell competition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Imaginal wing discs from late third-instar larvae were gammairradiated to induce clones of rapidly growingMinute − cells in a background of slowly growingMinute cells and culturedin vivo for periods up to 18 days. Clones in discs cultured for 16 to 18 days did not grow significantly larger than clones in uncultured controls, indicating that competition between populations of cells having potentially different mitotic rates does not occur in imaginal discs after their growth is completed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 280-284 
    ISSN: 1432-041X
    Schlagwort(e): Evagination ; Morphogenesis ; Metamorphosis ; Intersexual genital disc ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Morphogenetic movements of the intersexual genital disc of thedoublesex-dominant mutant ofDrosophila melanogaster were followed during metamorphosis. Intersexual genital discs contain well developed genital primordia of both sexes as well as an anal primordium, and all of these primordia evaginate simultaneously. The female genital primordium is deflected to the ventral side by the male genital primordium which is located anterior to it. Subsequently the anterior parts of the two genital primordia project their internal appendages in parallel in the anterior direction. The morphogenetic movements closely resemble those of the corresponding parts of normal males and females. The disc opens at the stalk along the posterior edge and the two genital primordia completely evert their posterior parts. These areas undergo complex rearrangements whereby the anlage for the male genital arch as well as that for the 8th tergite evert and move around the lateral side of the disc. They both fuse dorsally after enclosing the anal tube. The formation of the characteristic abnormalities of the intersexual genitalia seems not to result simply from spatial problems of the simultaneous evagination of the genital anlagen but rather to be a direct result of the ambiguous genetic signalling in the intersexual cells of these primordia.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 337-346 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gynandromorphs ; Genital disc ; Compartments ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The genital imaginal disc ofDrosophila differentiates the terminalia, i.e. the genitalia and analia, of both sexes. It represents a composite anlage, containing a female genital primordium, a male genital primordium and an anal primordium. In normal males and females, only one of the two genital primordia differentiates; the other is developmentally repressed. Therefore, cell-lineage relationships between the male and female genital primordia can only be studied in sexual mosaics which differentiate female and male cells. We producedMinute (M)‖non-Minute(M+) gynandromorphs and selected those with sexually mosaic terminalia for a cell-lineage analysis. In these mosaics, either the male (XO) or female (XX) cells wereM + and thus had a growth advantage. The differential growth rates served as a tool to detect clonal restrictions. In control gynandromorphs (M +‖M +), the amount of female genitalia differentiated was largely independent of the amount of male genitalia present. In contrast, male and female anal structures, as a rule, added up to one full set. The same was true for the experimentalM‖M + gynandromorphs, but the contribution ofXX andXO cells to mosaic terminalia changed drastically due toM + cells competing successfully against the more slowly growingM cells. Specific subsamples ofM‖M + gynandromorphs showed thatM cells in a non-mosaic primordium are shielded from cell competition taking place in the neighbouring mosaic primordium. We conclude that the three primordia of the genital disc represent developmental compartments. In the genital primordia, even developmentally repressedM + cells compete successfully against developmentally activeM cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 98-107 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Neoplasms ; Promotion ; Regeneration ; Temperature-sensitive ; Imaginal discs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In this paper we present an analysis of the behavior ofl(2)gl tsimaginal wing discs during culture in adult hosts. Thel(2)gl tslarvae reared at 29° C contain two types of wing discs, those that are morphologically normal and those that are abnormal. When discs of both types are cultured in adult hosts at 29° C, the restrictive temperature, they give rise to transplantable neoplastic tissue. However, when the 29° C reared discs are cultured at 15° C, the permissive temperature, the morphologically normal discs maintain their morphology, but the morphologically abnormal discs give rise to neoplasms. Thel(2)gl tslarvae reared at 15° C contain only morphologically normal discs. When these discs are cultured in adult hosts at 29° C they give rise to neoplasms, however if the discs are cultured at 15° C they maintain their normal morphology. These results demonstrate: (1) that all wing imaginal discs obtained from 29° C rearedl(2)gl tslarvae are competent to undergo neoplastic development, (2) the morphologically abnormal discs obtained from the 29° C rearedl(2)gl tslarvae are committed to neoplastic development, (3) the neoplastic development of the morphologically normal discs is temperature dependent, (4) once the neoplastic development of thel(2)gl tsdiscs has been initiated the process is not readily reversible. In addition, the ability ofl(2)gl tswing discs to perform epimorphic regulation was tested by amputating morphologically normal permissively rearedl(2)gl tswing discs and culturing both fragiments at the permissive temperature. Fragments of control wild-type discs maintained their morphology during culture at the permissive temperature. However, both fragments of txel(2)gl tsdiscs became neoplastic. This result is discussed with respect to a possible role for thel(2)gl +function in epimorphic regulation and with respect to the phenomena of tumor promotion in vertebrates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 103-111 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Polytene Chromosomes ; Ecdysteroids ; Fat Body
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Changes in polytene chromosome 3 L puffing patterns in the fat body ofDrosophila melanogaster larvae and prepupae are compared to those in the salivary gland. While some general features are common to the two tissues, there are differences which reflect their different developmental roles. In vitro experiments with fat body chromosomes show that they have a distinct response to ecdysteroids which is different from that of salivary gland chromosomes, and which does not,in this culture system, reproduce the changes observed in normal development. In short term culture experiments, the fat body chromosomes appear more sensitive to ecdysteroids than the salivary gland chromosomes and, although 20-OH ecdysone is more active than ecdysone in these assays, the possibility is not excluded that ecdysone has a role in normal development as it appears to alter gene activity at physiological levels in these cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 293-300 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Positional information ; Homology ; Intercalary regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The regulative behavior of fragments of the imaginal discs of the wing and first leg was studied when these fragments were combined with fragments of other thoracic imaginal discs. A fragment of the wing disc which does not normally regenerate when cultured could be stimulated to regenerate by combination with certain fragments of the haltere disc. When combined with a haltere disc fragment thought to be homologous by the criteria of morphology and the pattern of homoeotic transformation, such stimulated intercalary regeneration was not observed. Combinations of first and second leg disc fragments showed that a lateral first leg fragment could be stimulated to regenerate medial structures when combined with a medial second leg disc fragment but not when combined with a lateral second leg disc fragment. Combinations of wing and second leg disc fragments showed that one fragment of the second leg disc is capable of stimulating regeneration from a wing disc fragment while another second leg disc fragment fails to stimulate such regeneration. It is suggested that absence of intercalary regeneration in combinations of fragments of different thoracic imaginal discs is a result of homology or identity of the positional information residing in the cells of the fragments. The pattern of correspondence of positional information revealed by this analysis is consistant with the pattern of homology determined by morphological observation and by analysis of the positional specificity of homoeotic transformation among serially homologous appendages. The implications of the existence of homologous positional information in wing and second leg discs which share a common cell lineage early in development are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 335-339 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gap junction ; Wing disc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The distribution of gap junctions in mature larvalDrosophila melanogaster wing discs was analyzed by means of quantitative electron microscopy. Gap junctions are non-randomly distributed in the proximal-distal disc axis and in the apical-basal cell axis of the epithelium. In the epithelial cells, the surface density, number and length of gap junctions are greatest in the apical cell region and distal disc region. The average gap junction surface density is 0.0572 μm−1 and 2.77% of the lateral cell surface is composed of gap junctions. In the adepithelial cells, the gap junction surface density is 0.0005 μm−1 and 0.06% of the cell surface is composed of gap junctions. No gap junctions were observed between epithelial cells and adepithelial cells. The absolute area of gap junctions was estimated in a proximal-distal strip of cells in the disc and is considerably less in the folded regions of the epithelium compared to the flat notum and wing pouch regions. The results are discussed with respect to pattern formation and growth control in imaginal discs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 188 (1980), S. 163-177 
    ISSN: 1432-041X
    Schlagwort(e): Yolk sac ; Ultrastructure ; Embryogenesis ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Changes at the ultrastructural level during germ band extension in the embryo ofDrosophila melanogaster are described. Cytoplasmic connections between cells and the yolk sac are present during initial cellular movements. At this time, a continuous system of microfilaments is present adjacent to the membranes in the connections and at the periphery of the yolk sac. As germ band extension progresses, this system becomes discontinuous, and microfilaments are apparent only in the immediate vicinity of the connections. Cytoplasmic connections are disassembled at approximately the midpoint of extension; at the same time, extensive membrane associations develop between germ band cells and between these cells and adjacent yolk sac membranes. Positioning and orientation of cytoplasmic connections suggest that the yolk sac, via these connections, is actively involved in the cellular movements of early germ band extension.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 189 (1980), S. 57-67 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Ecdysone deficient mutants ; Ecdysteroid titer ; Ring gland ; Fine structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This paper describes two ecdysone-deficient, recessive-lethal mutants,lethal(1)giant ring gland (grg) andlethal(1)suppressor of forked mad-ts (mad-ts: Jürgens and Gateff 1979) and compares their ecdysteroid titers with that of the wild-type. Mutant larvae show a much reduced ecdysteroid content, amounting to 1/10 to 1/30 of the wild-type values, but never a true titer peak. They fail to pupate and die after 1–3 weeks. Ecdysteroid feeding elicits different responses in the larvae of the two mutants.mad-ts larvae pupate within 24 h, thus showing that their low ecdysteroid titer is directly connected to their inability to pupate.mad-ts resembles the mutantlethal (3)ecdysone-1 ts (Garen et al. 1977). Thegrg mutant larvae, on the other hand, fail to pupate after 20-hydroxyecdysone feeding as well as injection. The primary defect of thegrg mutant is not entirely clear. Thegrg larval salivary gland cells appear to possess normal ecdysteroid receptors. Furthermore, the low ecdysteroid titer ingrg is not the result of an increased ecdysteroid catabolism. The primary defect in the mutant may lie in the malfunctioning neurosecretory cells which do not show neurosecretion in histological preparations. Further support for this notion comes from electronmicrographs of the enlargedgrg ring glands which, in contrast to the wild-type, do not possess nerve endings. In the wild-type three ecdysteroid peaks were found: one shortly before puparium formation, the second at approximately 12 h and the third at about 30 h after pupation. The ecdysteroid titer peak in late third instar, wild-type larvae is mainly due to the presence of 20-dydroxyecdysone as shown by radioimmunoassays after thin layer chromatography and derivatization followed by gas liquid chromatography and mass spectroscopy. In addition, a number of unidentified polar and apolar metabolites were also present.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 188 (1980), S. 157-161 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Compartments ; Distal outgrowth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Peripheral tissue of the imaginal wing disc gives rise to the proximal mesothoracic structures of the adult. Pieces of peripheral tissue, which have no regenerative capacity when cultured as intact fragments, are capable of distal outgrowth (regeneration) after dissociation and reaggregation. This ability depends on the region of the disc periphery from which the fragment is taken. Extensive distal outgrowth occurs in reaggreages of a fragment containing equal proportions of tissue from anterior and posterior developmental compartments. The extent of outgrowth decreases as the proportion of posterior tissue is reduced, so that a fragment containing only anterior tissue shows no regeneration after dissociation. Limited distal outgrowth occurs in reaggregates of a wholly posterior fragment, but the regenerative capacity is increased greatly when a small amount of anterior tissue is included. It is concluded that distal outgrowth in the wing disc requires an interaction between cells of the anterior and posterior compartments.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 189 (1980), S. 91-96 
    ISSN: 1432-041X
    Schlagwort(e): Epimorphic regulation ; Drosophila ; Imaginal discs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It has been known for many years that when a wing disc ofDrosophila is bisected, and the fragments cultured in adult females, regulation occurs and either a complete disc is regenerated or the fragment is duplicated. We have investigated how this regeneration process occurs. To establish which cells contribute to the regenerate, and thus determine if regeneration is the result of epimorphic regulation, fragments of discs, after culture in an adult for one to five days, were exposed to3H-thymidine to label replicating cells. Imaginal discs, both whole and as regenerating fragments, undergo some DNA replication which is distributed throughout the disc, but cut discs frequently show clusters of labelled cells around the wound, indicating that regeneration is probably epimorphic.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 11-21 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Ecdysteroid ; Lethal mutant ; Morphogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Imaginal disc development in the non-pupariating lethall(1)npr-1, a mutant that maps to an ecdysone early puff site, is studied in situ, in vitro and in transplanted discs. Disc development is slightly abnormal from the middle of the third instar with severe abnormalities appearing after the rise in 20-hydroxyecdysone that triggers metamorphosis. The mutant discs only partly evaginate and do not undergo any of the detailed morphological changes characteristic of metamorphosis. Treatment of the mutant dises in vitro with colcemid and trypsin facilitates evagination but the appendages remain morphologically abnormal. A number of differentiative processes occur in mutant discs in situ and in discs transplanted into wild type hosts in spite of the absence of normal morphogenesis. Implications of the observations for normal disc development are discussed. Possible modes of action of thel(1)npr-1 gene are also discussed in light of the observation that the mutant gene maps to a locus which is thought to have a regulatory function in development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 132-138 
    ISSN: 1432-041X
    Schlagwort(e): Maternal effect mutant ; Homeotic-mutants ; Pattern formation ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The temperature sensitive mutationfs(l)h is characterized at the restrictive temperature of 29°C by both a maternal effect responsible for the early embryonic lethality and pupal zygotic lethality. The two phenotypes are inseparable and map at a short deletion in the X chromosome (7Dl, 7D5-6). At semipermissive temperatures, hemizygous mutant females produce adults with morphological defects, such as organ deficiencies and homeotic transformations of haltere to wing and third leg to second leg. These defects depend on the maternal genotype and are governed by an early temperature sensitive period, which covers the end of oogenesis and the first hours of embryogenesis. Furthermore, this maternal effect mutation interacts with some dominant mutations of the bithorax system. These properties suggest thatfs(l)h is somehow involved in segmental determination.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 1-10 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Grandchildless ; Pole cells ; ts-mutant ; Cytoplasmic determinant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two temperature-sensitive sex-linkedgrandchildless (gs)-like mutations (gs(1)N26 andgs(1)N441) were induced by ethylmethane sulphonate inDrosophila melanogaster. They complemented each other and mapped at two different loci (1−33.8±0.7 forgs(1)N26 and 1−39.6±1.7 forgs(1)N441), which were not identical to those of any of thegs-like mutants reported in earlier work. Homozygous females of the newly isolated mutants produced eggs that were unable to form pole cells and developed into agametic adults. Competence of the embryos to form pole cells was not restored by wild-type sperm in either mutant; that is, the sterility caused by these mutations is controlled by a maternal effect. Fecundity and fertility ofgs(1)N26 females were low, and their male offspring showed a higher mortality than that of female offspring, causing an abnormal sex ratio. The frequency of agametic progeny was 93.1% and 55.8%, when the female parents were reared at 25° C and 18° C, respectively. In eggs produced by thegs(1)N26 females reared at 25° C, the migration of nuclei to the posterior pole was abnormal, and almost no pole cell formation occurred in these egg. Furthermore, half of these eggs failed to cellularize at the posterior pole. When the females were reared at 18° C, almost all of the eggs underwent complete blastoderm formation, and in half of these blastoderm embryos normal pole cells were formed. In the other mutant,gs(1)N441, the fecundity and fertility of the females were normal. The agametic frequency in the progeny was 70.8% and 18.6% when the female parents were reared at 25° C and 18° C, respectively. In the eggs laid by females reared either at 25° C or at 18° C, the migration of nuclei to the periphery and cellularization proceeded normally; nevertheless, in the majority of the embryos no pole cell formation occured at the stage when nuclei penetrated into the periplasm. When the females were reared at 18° C, some of the embryos from these females formed some round blastoderm cells with cytologically recognizable polar granules and nuclear bodies, which are attributes of pole cells. The temperature sensitive period ofgs(1)N441 was estimated to extend from stage 9 to 13 of King's stages of oogenesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 308-312 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; ts-Suppressor mutant ; Glue proteins ; Intermolt puffs ; Electrophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The l(1)su(f)ts67g mutation has been shown to suppress the developmentally regulated expression of glue protein genes at 30°C. Transferring mutant larvae to the restrictive temperature before the end of the second larval instar results in the absence or extreme reduction of glue protein synthesis while general protein synthesis is unaffected. At the same time, the three glue protein correlated chromosomal regions 3C, 25B, and 68C continue to show prominent puffs. The results suggest that the mutation may be affecting the processing or translatability of specific mRNAs rather than the translational machinery itself.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 28-36 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Polarity ; Maternal effect ; Nurse cells ; Embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutationdicephalic (dic) affects follicle development and thereby alters the antero-posterior polarity of embryonic patterning. It maps at a single locus (3–46.0±1.0) and can be characterized as a semi-dominant maternal effect mutation with low penetrance. Indic follicles, the 15 nurse cells form two clusters located at opposite poles of the oocyte; the numerical distribution of the nurse cells among the clusters varies from 7:8 to 1:14. Thedic egg shell carries a micropyle (anterior marker) at either pole, but the misshapen respiratory appendages are restricted to one of the two poles in most eggs. The malformed eggs rarely yield larvae and these are always abnormal anteriorly and/or posteriorly. The segment pattern expressed in their cuticle may represent two anterior parts of opposite polarities (double head type), two posterior parts of opposite polarities (double abdomen type, rare) or show uniform polarity. Lability of organization at the cystocyte stage appears as the primary developmental defect of the mutant.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 48-50 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Hybrid lethality ; Imaginal discs ; Interspecific transplantation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Females ofDrosophila melanogaster, crossed with males ofDrosophila mauritiana, produce only female offspring. The male hybrid larvae grow very slowly, fail to pupate and die after prolonged larval life. Imaginal discs from these male hybrids transplanted into Drosophila melanogaster larvae can give rise to adult structures with normal patterns. Differentiation of hybrid imaginal disc tissue is improved by short term culture in non-hybrid larvae prior to metamorphosis, suggesting that the hybrid larval haemolymph is inadequate to sustain normal imaginal disc growth. This may represent the physiological basis of the reproductive isolating mechanism separating the twoDrosophila species
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 270-274 
    ISSN: 1432-041X
    Schlagwort(e): Fate map ; Repressed primordium ; Sex determination ; Genital disc ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The female genital disc ofDrosophila melanogaster was cut into distinct fragments, and the prospective fates of the fragments were determined by putting them through metamorphosis in host larvae. The dorsal epithelium contains the anlagen for the anal plates and parovaria, as well as the repressed male genital primordium. The ventral epithelium gives rise to all of the female genital structures except for the parovaria. The results were compared with published fate maps and observations made in experiments with sex-transforming mutations. This allowed us to establish a detailed three-dimensional fate map of the female genital disc, which shows a well-developed female genital primordium in the ventral epithelium, a repressed male genital primordium in the anterior part of the dorsal epithelium and an anal primordium in the posterior region of the dorsal disc epithelium.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 285-294 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Cell degeneration ; Imaginal disc ; Basal lamina ; Blood cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutationsvestigial (vg; recessive) andUltravestigial (vg U; dominant) ofDrosophila melanogaster give rise to identical mutant adult phenotypes in which much of the cases this results from cell death in the presumptive wing margin of the wing disc in the third larval instar, but the process of cell degeneration is quite different in the two mutants. Invg cell death occurs continuously throughout the third larval instar, while invg U it occurs only in the early third instar. Cells fragment and some of the fragments condense, becoming electron dense (“apoptosis”). Both condensed and ultrastructurally normal cell fragments are extruded to the basal side of thevg disc epithelium. They accumulate under the basal lamina in the wing pouch area until they are phagocytosed by blood cells entering the wing pouch during the six hours following pupariation. Fragments are not extruded from thevg U epithelium but are apparently phagocytosed by neighboring epithelial cells. The basal lamina undergoes mophological changes following pupariation and is phagocytosed by blood cells in both wild-type andvestigial, but investigial the degenerated cell fragments are also engulfed by the same blood cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gap junction ; Imaginal disc ; Pattern formation ; EM Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Developmental changes in the distribution of gap junctions in early, mid and late third larval stage wing discs and in pupariation+6 h and pupariation+24 h stage wing discs fromDrosophila melanogaster were analyzed by quantitative electron microscopy. Gap junctions occur in all 12 intradisc regions examined in each of the five developmental stages. Their distribution is non-random and changes during development which suggests that they are developmentally regulated. The gap junctions are not static structures, rather they grow and regress during development. The changes tend to be gradual ones without sudden increases or decreases. Gap junctions continuously form and grow in size throughout the third larval stage and during the first 6 h following pupariation. Their surface density, number, percent of the lateral plasma membrane area, and absolute area as well as the lateral plasma membrane surface density all increase during this time. Between pupariation+ 6 h and pupariation+24 h all but one of these parameters decrease indicative of gap junctional breakdown. Gap junctions are most numerous and change least during development in the apical cell regions where intercellular contacts are close and stable. They change most in the basal cell regions where intercellular contacts tend to be looser and change during development. The most dramatic change is in the absolute area which increases by a factor of 23 between the early third larval stage and pupariation+24 h. At pupariation the rate of gap junction growth undergoes a transient increase before the phase of disassembly begins. Developmental changes in gap junction surface density are closely coupled with changes in the lateral plasma membrane surface density which suggests that these may be coregulated. Evidence from mutants suggests that when the number and density of gap junctions fail to increase in proportion to lateral plasma membrane growth, wing disc development will be abnormal. Our results support the idea that some minimum gap junction density is required for normal development and that this must increase as development proceeds. The results are consistent with the notion that gap junctions are involved in pattern formation and growth control and are discussed with respect to the acquisition of competence for metamorphosis, disc growth, disc morphogenesis and changes in the hormonal environment.
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    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 317-326 
    ISSN: 1432-041X
    Schlagwort(e): Neurogenic mutations ; Topological specificity ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Neurogenic mutations have been found to cause the neuralization of certain regions of the ectoderm and yet to permit normal development of the remaining embryonic cells. Thus, it seems that the activity of the wild-type alleles of these genes is dispensable in a considerable fraction of the embryo during wild-type development. This effect might be a consequence of the cells' position within the embryo; alternatively, it might be independent of the position but be due rather to the genetic activity experienced by the cells previous to their commitment. The results described in this paper indicate that genes controlling patterning along the embryonic dorso-ventral perimeter (dorsal and Toll) are epistatic to genes controlling neurogenesis, their activity deciding which ectodermal cells are susceptible to neurogenesis. Using alleles with low expressivity, evidence was obtained showing that the tracheal placodes define the boundary of the territory which has neurogenic abilities at thoracic and abdominal levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 210 (2000), S. 190-199 
    ISSN: 1432-041X
    Schlagwort(e): Key words Ventral neuroectoderm ; Cell shape ; Achaete-scute complex ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  In the embryonic ventral neuroectoderm of Drosophila melanogaster the proneural genes achaete, scute, and lethal of scute are expressed in clusters of cells from which the neuroblasts delaminate in a stereotyped orthogonal array. Analyses of the ventral neuroectoderm before and during delamination of the first two populations of neuroblasts show that cells in all regions of proneural gene activity change their form prior to delamination. Furthermore, the form changes in the neuroectodermal cells of embryos lacking the achaete-scute complex, of embryos mutant for the neurogenic gene Delta, and of embryos overexpressing l’sc suggest that these genes are responsible for most of the morphological alterations observed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 188 (1980), S. 179-185 
    ISSN: 1432-041X
    Schlagwort(e): Determination ; Germ-line ; Somatic cells ; Inhibitor gradient hypothesis ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A hypothesis is presented which explains the segregation of germ cells from somatic cells, and the subsequent determination of both cell types with a single mechanism. This hypothesis is in part based on that of Meinhardt (1977) and can be summarized as follows: In the newly fertilized egg, the action of a sink in the pole plasm leads to the formation of an anterior-posterior gradient of an inhibitor. The concentration of this inhibitor in the posterior 20% of the egg is below that needed to repress synthesis of an activator. When, during the nuclear division stage, nuclei enter this posterior region, synthesis of the activator begins. As the activator is autocatalytic, this leads to the formation of a peak of activator in this region; and since the activator also catalyses the synthesis of the inhibitor, a peak of inhibitor is formed in the same place. The inhibitor then diffuses anteriorly through the periplasm, forming a posterior-anterior gradient. The presence of this inhibitor in the periplasm causes the nuclei that enter the periplasm to form blastoderm cells and to take up particular segmental states appropriate to their position, while those that remain in the yolk-containing plasm develop into vitellophages. The action of the sink in the pole plasm is postulated to result in the formation of the pole cells, and subsequently to direct some of these into forming cells of the germ-line.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 189 (1980), S. 1-15 
    ISSN: 1432-041X
    Schlagwort(e): Cell line ; Drosophila ; Ecdysone ; Ecdysterone ; Hormones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Cells of the line Kc, derived fromDrosophila melanogaster embryos, extend long processes when exposed to ecdysteroid hormones. We have devised a quantitative assay for this morphological response, using the subline Kc-H. The assay was used to characterize the conditions required for the response. A halfmaximal response is elicited by approximately 10−8M 20-hydroxyecdysone; the response is saturated by 10−7M 20-hydroxyecdysone, which causes detectable elongation within a few hours, and a maximal response after 2–3 days. The response occurs substantially normally in the absence of serum, during growth in suspension, and in over-crowded cultures. It is not elicited by cyclic nucleotides, vertebrate growth factors, or a variety of other non-ecdysteroid reagents. Of 60 ecdysteroid compounds tested, only those which were active in other insect test systems elicited the response, and the concentrations required were approximately proportional to the concentrations active in other in vitro systems. We conclude that the response of Kc cells to 20-hydroxyecdysone retains basic features of the ecdysteroid response of intact tissues and therefore that Kc cells are a useful model system for studying ecdysteroid action.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 189 (1980), S. 187-196 
    ISSN: 1432-041X
    Schlagwort(e): Eggshell ; Chorion ; Peroxidase ; Crosslinking ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 301-303 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Geographic strains ; Chorion genes ; Electrophoretic variants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Further IF screening ofDrosophila melanogaster geographic strains has revealed a variant of the s19 major chorion protein. Developmental analysis of F1 hybrids indicates that the source of the variation is found in the structural gene for this protein. The linkage group of the variant gene was determined to be the third, and the gene was localized by several methods of recombination analysis. The s19 gene was found to be tightly linked to thesepia locus, as had been previously found for the s18 gene (Yannoni and Petri 1980). Lack of recombination between the s19 and s18 genes in double heterozygotes suggested that these two genes are within 0.3 map units of each other. Although more precise localization of the s19 gene failed, the s18 gene could be more specifically located to the right ofsepia, betweensepia andhairy. Contrary to our prediction (ibid.), the s19 and s18 genes have been found to be tightly linked in spite of the fact that they display somewhat different developmental stage specificity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 190 (1981), S. 370-373 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Homoeotic mutants ; Ventral cord
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We describe a set of cells in the central nervous system of theDrosophila embryo which are restricted to the thoracic ganglia in the wildtype. Taking these cells as indication of thoracic identity, we find that the ventral cord of embryos homozygous mutant for different bithorax functions and for Polycomb undergoes homoeotic transformations equivalent to those observed in the larval cuticle.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 42-55 
    ISSN: 1432-041X
    Schlagwort(e): Clonal analysis ; Growth ; Cell lineage ; Genital disc ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary InDrosophila, the terminalia (i.e. internal and external analia and genitalia, except the gonads) are formed by the genital disc. Comparative studies suggested that this disc may have evolved through fusion of the imaginal primordia of the last 3 or 4 abdominal segments. The present report describes the clonal relationships within the complex genital disc. Genetically marked cell clones were induced in male and female embryos and larvae heterozygous for cell marker mutations. 1) Frequencies and sizes of clones suggest that the embryonic disc anlage consists of 14–17 precursor cells: 4–6 for the analia, some 7 for the male genitalia, and 3–4 for the female genitalia. These cells grow exponentially during larval development. 2) In both sexes, the clones were confined to either analia or genitalia, suggesting two separate cell lineages already established at blastoderm. 3) Internal and external genitalia remain in the same compartment at least up to 60 h (end of first instar). 4) A clonal restriction appeared around 84 h (mid second instar), separating a dorsal from a ventral part in the male genitalia. The ventral compartment comprises the ventral part of the lateral plate and clasper, hypandrium, and all internal genitalia. No such boundary was detected in the female. 5) In the female, analia and parovaria originate from the same precursors; another cell lineage forms eighth tergites, vaginal plates, oviduct, receptacle, and spermathecae. 6) In female analia, dorsal and ventral plate share common precursors at least up to 84 h. A medio-lateral boundary may appear at 84 h in the ventral anal plate. No clonal restriction was found in the male analia. 7) At all times, clones could cross between left and right sides of the symmetrical terminalia; they consistently did so via ventral structures. 8) The results are discussed in a phylogenetic context, and we propose that the clonal relations reflect the evolution of the complex genital disc.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 191-201 
    ISSN: 1432-041X
    Schlagwort(e): Neurogenic mutants ; Maternal effects ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The size of the neurogenic region ofDrosophila melanogaster is under the control of several genes of zygotic expression. Lack of function from any of those genes produces an increase of the size of the neurogenic region at the expense of the epidermal anlage. However, differences exist in the extent of neuralisation achieved by each of the genetic loci upon mutation. The present results show that in the case ofN andmam phenotype differences are due to different contributions of maternal gene expression. This could be shown by studying the phenotype which appeared in mutant embryos when the oocytes developed from homozygous mutant precursor cells. Clones of mutant cells were induced in the germ line of females heterozygous for the neurogenic mutationin trans over germ line dependent, dominant female sterile mutations. After removing maternal information the phenotype ofN andmam mutants became identical in both cases. Furthermore maternal information fromN + was found to be necessary for viability of the wildtype.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 211-214 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Clonal analysis ; Sex determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutationSxl f , located on the X-chromosome, is a sex-limited recessive lethal that specifically kills 2X; 2A flies while it does not affect X; 2A flies (Cline 1978). We have analyzed the role ofSxl f on sex determination by a clonal analysis of a new spontaneous allele,Sxl fLS . Female embryos and larvae heterozygous forSxl fLS were irradiated at different times of development to generate homozygousSxl fLS clones which were recognized by linked marker mutations. We have studied the phenotype of such clones on sexually dimorphic regions of the fly (foreleg basitarsus, 5th, 6th and 7th tergites, analia and external genitalia). Despite their female (2X; 2A) chromosomal constitution, clones homozygous forSxl fLS differentiated male structures. These results confirm and extend the preliminary report of Cline (1979). They show that the wildtype product ofSxl f is required for female development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 192 (1983), S. 62-74 
    ISSN: 1432-041X
    Schlagwort(e): Early neurogenesis ; Neurogenic mutants ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The central nervous system (CNS) ofDrosophila develops from precursor cells called neuroblasts. Neuroblasts segregate in early embryogenesis from an apparantly undifferentiated ectoderm and move into the embryo, whereas most of the remaining ectodermal cells continue development as epidermal cell precursors. Segregation of neuroblasts occurs within a region called the neurogenic field. We are interested in understanding how the genome ofDrosophila controls the parcelling of the ectoderm into epidermal and neural territories. We describe here mutations belonging to seven complementation groups which effect an abnormal neurogenesis. The phenotypes produced by these mutations are similar. Essential features of these phenotypes are a conspicuous hypertrophy of the CNS accompanied by epidermal defects; the remaining organs and tissues of the mutants are apparently unaffected. The study of mutant phenotype development strongly suggests this phenotype to be due to misrouting into the neural pathway of development of ectodermal cells which in the wildtype would have given rise to epidermal cells, i.e. to an initial enlargement of the neurogenic region at the expense of the epidermogenic region. These observations indicate that the seven genetic loci revealed by the mutations described in this study contribute to control the neurogenic field. The present results suggest that in wildtype development neurogenic genes are supressed within all derivatives of the mesoderm and endoderm and some derivatives of the ectoderm, and conditionally expressed in the remaining ectoderm. The organisation of the neurogenic field in the wildtype is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 296-307 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In order to identify X-chromosomal genes required inDrosophila for early patterning and morphogenesis, we examined embryos hemizygous for EMS-induced lethal mutations to determine which of those mutations cause gross morphological defects. Embryos from 2711 lethal lines, corresponding to 3255 lethal point mutations were studied. Only 21% caused death during embryogenesis and of these, only one-sixth, or 3% of the total lethals, were associated with defects visible in the final cuticle pattern. Of the 114 point mutants causing visible cuticle defects, 76 could be assigned to 14 complementation groups. An additional 25 mutations mapping to regions of the X-chromosome not covered by male fertile duplications were assigned to six complementation groups based on similarities of map position and phenotype. Thirteen mutations could not be assigned to complementation groups. All mutations allowed normal development through the cellular blastoderm stage, the first defects associated with the earliest acting loci being observed shortly after the onset of gastrulation. The phenotypes of the various loci range from alterations in segment pattern or early morphogenetic movements to defects in final pigmentation and denticle morphology. Cuticle preparations were also examined for 63 deletions spanning in total 74% of the X-chromosome, as well as for 8 deletions and point mutations derived in saturation mutagenesis screens of the fourth chromosome (Hochman 1976). With the exception of defects in head morphology and defects in cuticle differentiation, none of the hemizygous deletions showed phenotypes other than those predicted by point mutations known to lie in those regions. No deletion caused new or unknown alterations in gastrulation, segmentation or cuticle pattern.These results suggest that the number of genes required zygotically for normal embryonic patterning is small and that most, if not all such loci, are represented by point mutations in our collection.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 58
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The thin region of the peripodial membrane is confined to the area overlying the distal anlagen in thoracic discs. During the early stages of evagination the peripodial membrane is greatly stretched, but does not rupture. The appendage then evaginates through the stalk, probably by means of a contraction of the peripodial membrane. The cells of the peripodial membrane of leg and wing discs persist and differentiate sheets of trichomes characteristic of the ventral and lateral thorax. This is discussed in relation to imaginal disc fate maps.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 263-265 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Biothorax complex ; Prothoracic transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary If, early in development, theUbx + gene is removed by mitotic recombination from cells of the meso-and metathoracic leg primordia, theseUbx − cells develop as in the posterior prothoracic leg. We show that this transformation, termedpostprothorax, is a discrete genetic function that is independent of other homeotic transformations such asbx, pbx orbxd, which also result from the inactivation of theUbx gene.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 283-295 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The present report describes the recovery and genetic characterization of mutant alleles at zygotic loci on the third chromosome ofDrosophila melanogaster which alter the morphology of the larval cuticle. We derived 12600 single lines from ethyl methane sulfonate (EMS)-treatedst e orrucuca chromosomes and assayed them for embryonic lethal mutations by estimating hatch rates of egg collections. About 7100 of these lines yielded at least a quarter of unhatched eggs and were then scored for embryonic phenotypes. Through microscopic examination of unhatched eggs 1772 lines corresponding to 24% of all lethal hits were classified as embryonic lethal. In 198 lines (2.7% of all lethal hits), mutant embryos showed distinct abnormalities of the larval cuticle. These embryonic visible mutants define 45 loci by complementation analysis. For 32 loci, more than one mutant allele was recovered, with an average of 5.8 alleles per locus. Complementation of all other mutants was shown by 13 mutants. The genes were localized on the genetic map by recombination analysis, as well as cytologically by complementation analysis with deficiencies. They appear to be randomly distributed along the chromosome. Allele frequencies and comparisons with deficiency phenotypes indicate that the 45 loci represent most, if not all, zygotic loci on the third chromosome, where lack of function recognizably affects the morphology of the larval cuticle.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 308-325 
    ISSN: 1432-041X
    Schlagwort(e): Neurogenesis ; Pattern of neuroblasts ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This paper deals with morphological aspects of early neurogenesis inDrosophila, in particular with the segregation of neuroblasts from the neurogenic region of the ectoderm and the pattern formed by those wells within both the germ band and the procephalic lobe. The neurogenic ectoderm was found to contain neural precursors intermingled with epidermal precursors, extending from the midline up to the primordia of the tracheal tree along the germ band and laterodorsally in the procephalic lobe. Germ band neuroblasts segregate from the neurogenic ectoderm during a period of several hours according to characteristic spatial and temporal patterns. During the first half of the segregation process the pattern of germ band neuroblasts was found to be the same in different animals in both spatial arrangement and number of cells; this permitted the identification of individual neuroblasts from different embryos. Later in development several difficulties were encountered which precluded an exact description of the neuroblast pattern. The constitution of the neurogenic region is discussed in relation to the phenotype of mutants affecting neurogenesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 388-393 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Oogenesis ; Ring canals ; Oocyte determination ; Polarity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The pattern of intercellular connections between germ line cells has been studied in follicles of the mutantdicephalic (dic), which possess nurse cell clusters at both poles. Staining of follicles with a fluorescent rhodamine conjugate of phalloidin reveals ring canals and cell membranes and thus allows us to reconstruct the spatial organization of the follicle. Each germ line cell can be identified by the pattern of cell-cell connections which reflect the mitotic history of individual cells in the 16-cell cluster. The results indicate that in both wild-type anddicephalic cystocyte clusters one of the two cells with four ring canals normally becomes the pro-oocyte. However, in some follicles (dicephalic and wild-type) oocytes were found with fewer or more than four ring canals. Indic follicles, one or several nurse cells may become disconnected from the other cells during oocyte growth at stage 9–10. Such disconnected cells cannot later on empty their cytoplasm into the oocyte. This, in turn, might be of consequence for the determination of axial polarity of the embryo.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 193 (1984), S. 406-413 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The fusion of the eye-antennal discs during culturein vitro has been investigated, and the complex morphogenetic movements which occur during the formation of the head capsule of the insect are described. The initial contact between the eye anlagen is by means of cell processes spanning the gap between the two discs. Subsequently the two epithelia become firmly apposed, and then the integrity of the epithelium in the region of fusion breaks down, cells appearing to move to new positions in order to form an epithelium which unites the two discs. The epithelium eventually secretes a pattern of cuticular structures which is continuous between the derivatives of the two discs. Bristles on either side of the line of fusion are perfectly aligned, and structures such as the median ocellus, which are formed jointly by the cells of the two discs, differentiate normally. This is also found when left and right eye-antennal discs of different genotypes are placed side-by-side, indicating that processes of pattern regulation can occur in culture.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 188 (1980), S. 153-156 
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Embryogenesis ; mat (3) 1 mutation ; Two-dimensional gels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The synthesis of a protein which has been detected in blastoderm cells but not in pole cells (Gutzeit and Gehring 1979) has been studied further by means of two-dimensional gel electrophoresis. This protein could not be detected at the nuclear multiplication stage. The protein is translated from mRNA which is transcribed at the blastoderm stage since it is not synthesized in detectable amounts when embryos are injected with α-amanitin prior to the blastoderm stage. Also the protein could not be detected when RNA from freshly laid eggs was translated in vitro. Embryos from females which are homozygous for the mutationmat (3) 1 form pole cells but no blastoderm cells (Rice and Garen 1975). Thesemat (3) 1 embryos, as we will call them in this report, express the protein if aged for a period of time sufficient for completion of blastoderm cell formation in control wild-type embryos.mat (3) 1 embryos and embryos injected with α-amanitin show the same syndrome of visible developmental anomalies; however, the studied protein could only be detected inmat (3) 1 embryos but not in α-amanitin injected embryos.
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  • 65
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Geographic strains ; Chorion proteins ; Electrophoretic variants ; Chorion gene linkage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Drosophila melanogaster chorion proteins are characterized on one-dimensional isoelectric focusing (IF) gels. The six major chorion components previously identified on SDS gels are shown to resolve into at least 11 components in our IF system. IF screening of 102 geographic strains ofDrosophila melanogaster revealed seven cases of variation in major chorion components. Two strains, Crimea and Falsterbo, which were monomorphic for a variant B1 protein and two strains, Skafto and Lausanne, which were monomorphic for a variant C1 protein, were chosen for further study. After IF developmental analysis of F1 hybrids had indicated that the sources of the variation resided in the structural genes for these proteins, each variant was crossed to a multiply marked and inverted strain (BLT) to determine the linkage group of the variant gene. To localize genes to more specific sites multiply marked 3rd (SKERO) or X-chromosomal (CB1) (X-PLE) mapping strains were used. In both Crimea and Falsterbo the gene for the B1 protein is located near map location 26 on the 3rd chromosome. In both Lausanne and Skafto the C1 gene is located on the X chromosome. Hence, for the first time, we have demonstrated genetically the non-linkage of two chorion genes, B1 and C1.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 189 (1980), S. 147-153 
    ISSN: 1432-041X
    Schlagwort(e): Homeotic mutant ; Drosophila ; Clonal analysis ; Timing of gene action ; Determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Nasobemia (Ns) is a dominant homeotic mutant ofDrosophila melanogaster which converts parts or all of the antenna to mesothoracic leg.Ns has a temperature sensitive period between 48 and 60 h. The hypothesis thatNs acts during this period and is not required thereafter to maintain the homeotic transformation to leg was tested by removingNs fromNs/+ cells at different stages of development through X-ray induced somatic recombination. The expression of theNs homeotic transformation in recombinant wild type (+/+) cells increased sharply between 48 and 65 h. In clones induced after 65 h the expression of the leg transformation was equal in large and small +/+ clones. We interpret these results as supporting the hypothesis that transient action ofNs between 48 and 65 h switches antennal cells to a clonally stable leg determined state whose maintenance does not require futherNs action.
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 6 (1973), S. 150-155 
    ISSN: 1432-1041
    Schlagwort(e): Dopamine ; renal blood flow ; hypertension ; renal failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of an intravenous infusion of dopamine (0.5 to 1.25 µg/kg/min) for periods of between 36 and 105h has been studied in eight patients with hypertension and varying degrees of renal impairment. There was a significant rise in the glomerular filtration rate (GFR) from 31.2±20.2 to 42.8±26.8 ml/min (p〈.05) after four hours of the infusion but after 48 h of infusion the mean GFR was no different from the control value. The paraaminohippuric acid (PAH) clearance also rose from 129.8±115.4 ml/min to 173.1±164.3 ml/min (p〈0.05) after four hours of infusion, but like the GFR it was no different from control after 48 h of the infusion. The daily urine volumes increased significantly during the dopamine infusion from 2176.0±49.2 ml/day to 3809.0±118.8 ml/day (p〈0.002) but had returned to control values after 48 h of continuing dopamine infusion. Following the end of the infusion there was a significant reduction in the urine volume to 1213.0±195.0 ml/day (p〈0.001). There was a rise in sodium excretion during the dopamine infusion from 94.8±50.7 meq/day to 264.7±172.8 meq/day (p〈0.01) with a fall after the end of the infusion to 33.2±27.5 meq/day (p〈0.05). There was no change in the blood urea during the dopamine infusion but after stopping the infusion the blood urea rose from 83.5±39.4 mg% to 95.1±39.0 mg% (p〈0.02). We conclude that intravenous infusion of dopamine to patients with hypertension and renal impairment may produce initial clinical improvement but is of little therapeutic benefit when given for prolonged periods.
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 6 (1973), S. 217-219 
    ISSN: 1432-1041
    Schlagwort(e): Beta-blockade ; substituted indoles ; hypertension ; heart rate ; clinical trial ; pindolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Forty patients with essential hypertension were treated with a new beta-blocking agent, 4-2 (2-hydroxy-3-isopropyl-amino-propoxy)-indole, pindolol (Viskén®). Pindolol caused a significantly greater reduction of blood pressure in most of the patients than a placebo and the effects persisted for some time after its withdrawal. There were few side effects. Its mode of action and a safe dosage regime are discussed.
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 7 (1974), S. 401-405 
    ISSN: 1432-1041
    Schlagwort(e): Chlorthalidone ; spironolactone ; hypertension ; potassium deficiency ; diuretic ; Kühns' test
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Kühns' oral test for potassium deficiency (KDT) has been used to evaluate potassium balance after treatment with diuretics. The test was first standardised in 23 patients, both with and without known potassium deficiency. Subsequently, 18 patients with essential hypertension were investigated before and after the use of 3 different diuretics, each for a period of 6 weeks; all patients received all three forms of treatment but in different sequence. Before treatment the patients excreted an average of 121 mEq potassium a day in urine after oral administration of potassium 127 mEq (citrate). After treatment with chlorthalidone (Hygroton®), 50 mg a day, the excretion of potassium decreased significantly to 83 mEq, suggesting an intracellular deficit of it. Treatment with chlorthalidone 50 mg and potassium chloride 2 g daily (Hygroton — K®), led to potassium excretion of 100 mEq after loading, which was distinctly, but not significantly, larger than in the period of treatment with chlorthalidone alone. After chlorthalidone 50 mg daily and spironolactone (Aldactone “Searle”®), 25 mg q. i. d., the excretion of potassium was 121 mEq, which was the same as before treatment. The mean serum potassium before treatment was 4.4 mEq/l, after chlorthalidone 3.8 mEq/l, after chlorthalidone plus potassium chloride 3.9 mEq/l, after chlorthalidone combined with spironolactone 3.9 mEq/l. The results were in agreement with previously published investigations of “exchangeable potassium” after similar treatments. As the test for potassium deficiency gave better information about the amount of intracellular potassium in the body than analysis of serum potassium, it is suitable for the evaluation of potassium deficiency associated with diuretic therapy.
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 4 (1972), S. 217-221 
    ISSN: 1432-1041
    Schlagwort(e): Bethanidine ; guanethidine ; hypertension ; adrenergic blockade ; blood pressure ; dose response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A dosing schedule for the administration of oral bethanidine is described, which achieved optimal cumulative effect in each of 8 patients in 3 days or less. Individual patient dosage titration is necessary, because the required cumulative dose cannot be predicted on the basis of blood pressure, or creatinine clearance. The time course of the blood pressure response after the peak acute hypotensive effect was found to be variable and dependent upon the magnitude of effect and time of day. No blood pressure effect was noted in the recumbent position.
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 321-326 
    ISSN: 1432-1041
    Schlagwort(e): sotalol ; hypertension ; renal impairment ; chronic administration ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Ten hypertensive patients with moderate to severe impairment of renal function were treated with sotalol for 5 to 10 weeks (average 6.4 weeks). Dosage was individually titrated (range 80 to 480 mg daily). The drug was given once daily in the morning. In eight patients blood pressure was satisfactorily controlled. Higher steady-state levels were observed than have been reported after similar doses in patients with normal renal function. The apparent first-order elimination rate constant and plasma clearance were significantly correlated with glomerular filtration rate. For an anuric patient, serum half-life was calculated to be 69 h. In relation to the raised plasma levels, side effects were uncommon. Since sotalol is excreted predominantly via the kidney, therapy in patients with impaired renal function should start with a low dose and any increase in dosage should be made carefully. As the anti-hypertensive effect does not appear to be correlated with the plasma level or with tolerance, adjustment of dose should be based on clinical response.
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 19 (1981), S. 19-24 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; guanfacine ; central antihypertensives ; withdrawal ; catecholamines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary 1. Guanfacine (2–6 mg/day) a centrally acting antihypertensive drug, was effective in controlling blood pressure in 5 essential hypertensives and lowered plasma noradrenaline and urinary catecholamine excretion. 2. Withdrawal of guanfacine by blind substitution of identical placebo tablets under observation in hospital led to a gradual recovery of blood pressure over 2–4 days. 3. Salivary flow, which was reduced on guanfacine, returned to pretreatment levels by 2 days after withdrawal and significantly exceeded control for the next two days. 4. Urinary catecholamine excretion returned to pretreatment levels by 3 days but did not exceed control levels during the period of study. 5. Plasma noradrenaline returned gradually to pretreatment levels, and by day 4 significantly exceeded them. 6. No patient experienced symptoms suggesting catecholamine excess although four out of five reported a headache from the second day onwards. 7. Guanfacine, a centrally acting drug which pharmacologically resembles clonidine, has a slow offset of hypotensive effect over 2–3 days. Symptoms or biochemical evidence of catecholamine excess were not encountered within 48 h of withdrawal, possibly reflecting the longer duration of action and plasma half-life of guanfacine.
    Materialart: Digitale Medien
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 225-229 
    ISSN: 1432-1041
    Schlagwort(e): metoprolol ; hypertension ; slow-release preparations ; maximal exercise power ; fatigue
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The treatment of hypertension with a single daily-dose of a beta-blocker gives rise to high peak-plasma concentrations 1.5 h after ingestion. After slow release-preparations of beta-blockers, the peak concentrations are half those produced by the conventional preparation at the same oral dose. A frequently occurring side-effect of beta-blocker therapy is fatigue. In this study the effect of a single dose of metoprolol 300 mg, 200 mg, 200 mg slow-release and a placebo on maximal exercise power was tested in 6 healthy subjects, 1.5 h and 24 h after ingestion. Maximal exercise power was significantly reduced 1.5 h after ingestion of metoprolol 300 mg and 200 mg. No change was found 1.5 h after 200 mg of a slow-release preparation. The possible reasons for reduced maximal exercise power are discussed. It is concluded that use of a beta-blocker for the treatment of hypertension in a single daily-dose regimen may be a reason to prefer a slow-release preparation.
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 399-401 
    ISSN: 1432-1041
    Schlagwort(e): prazosin ; hypertension ; central monoaminergic neurons ; monoamine metabolites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Six hypertensive patients were treated with prazosin up to a final dose of 3–4.5 mg/day. There was a significant reduction of blood pressure. The cerebrospinal fluid (CSF) concentrations of the major metabolites of noradrenaline, dopamine and serotonin were unchanged. This indicates that the antihypertensive effect is not mediated via central monoaminergic neurons as suggested by animal studies.
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 105-108 
    ISSN: 1432-1041
    Schlagwort(e): renin ; angiotensin ; aldosterone ; hypertension ; hypoaldosteronism ; pseudohypoaldosteronism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary There is increased activity of the renin, angiotensin, aldosterone (RAA) system in infancy and childhood. An inverse relationship between plasma renin, aldosterone and age has been demonstrated. In childhood hypertension due to renovascular disease or pyelonephritic scarring peripheral plasma renin is increased. Renal vein renin measurements in children with renal hypertension have proved valuable in predicting surgical curability of the underlying lesion. The upper limit of normal for the renal venous renin ratio in normotensive children without renal disease is 1.5. Pharmacological blockade of the RAA system has a place in diagnosis and treatment of hypertensive children. The plasma renin aldosterone profile is diagnostically useful in the investigation of salt-wasting disease and can easily distinguish between aldosterone biosynthetic defects and pseudohypoaldosteronism.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 135-139 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; labetalol ; propranolol ; renal haemodynamics ; glomerular filtration rate ; blood pressure ; exercise ; renal blood flow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of exercise on renal haemodynamics was examined in young patients with mild essential hypertension. Four groups of subjects were studied: 13 normotensive, healthy control subjects, and 15 untreated, 11 propranolol-treated, and 6 labetalol-treated patients. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were measured during four consecutive periods, a pre-exercise control period, two exercise periods with loads of 450 kpm/min and 600 kpm/min, respectively, and a post-exercise control period. In the untreated patients RPF and GFR were lower during exercise than in the normotensive control subjects, whereas no significant differences were found at rest. In the propranolol-treated patients the reduction in RPF and GFR during exercise was more pronounced than in the untreated hypertensives. In the labetalol-treated patients however, RPF and GFR were reduced only to the same degree as in the untreated hypertensives. The reduced renal blood flow in propranolol-treated patients may be attributed to a compensatory increase in sympathetic activity caused by an impaired cardiac response to exercise. The lack of reduction in renal blood flow during labetalol therapy could partly be related to alpha-adrenergic blockade in the renal vascular bed induced by labetalol, and partly to the smaller reduction in cardiac output during labetalol than during propranolol therapy.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 231-235 
    ISSN: 1432-1041
    Schlagwort(e): molsidomine ; hypertension ; hypotension ; angina pectoris
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Molsidomine (M), a new long-lasting antianginal compound, was studied in 38 hypertensive patients to assess its antihypertensive properties. Six patients were selected for an acute, single dose comparative trial with placebo over 8 h after treatment. The remaining 32 patients were used in a 1 month trial to study the effect on BP of more prolonged treatment. Systolic, diastolic and mean BP were significantly reduced after a single dose of M 4 mg, and the effect lasted for about 8 h. M also inhibited the hypertensive response to isometric exercise in handgrip tests performed 1 and 8 h after M ingestion. A dose-related decrease in systolic and diastolic BP in the one month trial was also observed. In addition to its antianginal properties, M appears to possess an interesting effect on BP in mildly to moderately hypertensive patients. A fall in BP is also a valuable effect in coronary patients with augmented metabolic demands of the heart.
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  • 78
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; nifedipine ; beta-adrenoceptor blockade ; hypotensive action ; adverse effects ; combination therapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The antihypertensive effect of nifedipine (10–20 mg t.i.d.) given alone, or in combination with a beta-adrenoceptor blocking drug, was related to the observed plasma concentration during one dosage interval at steady-state (Pl-Nifss). The study was carried out as a within-patient comparison of treatment with nifedipine or placebo for 4 weeks. A highly significant reduction in blood pressure was obtained during monotherapy, as well as during combined treatment. The blood pressure reduction when nifedipine was added to beta-adrenoceptor blockade was of the same magnitude as that observed on nifedipine monotherapy. A considerable variation in Pl-Nifss was noted (range: 2–70 ng/ml). No significant correlation was found between the percentage reduction in blood pressure and Pl-Nifss in either of the two groups. There was a close relationship between Pl-Nifss and the concentration found 4 h after the morning dose. Side-effects were common during nifedipine monotherapy and were the reason for discontinuation of treatment in 4 of 18 patients. In contrast, none of the 9 patients on combined treatment dropped-out. In neither of the treatment groups was there any evidence for sodium retention and volume expansion during the first 4 weeks expressed as weight gain or signs of cardiac insufficiency. However, in 13 patients who continued on long-term treatment for 3–14 months, a definite need for concomitant diuretic therapy was found. The results indicate that nifedipine is effective in lowering blood pressure in patients with mild to moderate essential hypertension, either when given alone or in addition to beta-adrenoceptor blockade. It appears best tolerated as combination therapy. Long-term treatment requires addition of a diuretic. Pl-Nifss did not seem to be a major determinant of the magnitude of the hypotensive response.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 18 (1980), S. 375-382 
    ISSN: 1432-1041
    Schlagwort(e): calcium antagonist ; verapamil ; hypertension ; vasodilators ; plasma renin activity ; mode of action ; sodium balance ; fluid balance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In 12 in-patients with moderate uncomplicated hypertension, maintained on constant sodium intake for 15 days, single-blind oral administration of verapamil 80–160 mg t. i. d. for 10 days had a significant antihypertensive effect: in the supine position systolic blood pressure decreased from 177±5 to 150±3 mmHg, and diastolic pressure from 111±3 to 96±2 mmHg; standing values were similarly lowered from 171±7 to 143±4 mmHg, systolic, and from 118±4 to 97±2 mmHg, diastolic. The heart rate did not show any significant change (from 79±3 to 77±2 beats/min, supine, and from 92±3 to 87±3 beats/min, upright). The antihypertensive effect was uniform throughout the day, being similar 2, 3, 6 and 8 h after administration of a dose. Dynamic exercise (75–100 watts on a cycle-ergometer) caused identical increases in arterial pressure and heart rate on the last day of placebo and again on the last day with verapamil, but the peak levels of systolic pressure reached during exercise were lower after verapamil than with placebo, because of the lower blood pressure before exercise. Reduction of arterial pressure by verapamil was not accompanied by increased plasma renin activity, or by renal retention of sodium and water: there was a small increase in sodium excretion, at least during the first days of verapamil administration (from 107±15 to 113±15 mEq Na+/day), and a slight significant reduction in body weight (from 74.2±3.7 to 73.5±3.7 kg). It is concluded that oral administration of verapamil significantly lowers blood pressure without simultaneously inducing cardiac stimulation, renin secretion or salt and water retention.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 19 (1981), S. 309-315 
    ISSN: 1432-1041
    Schlagwort(e): guanfacine ; methyldopa ; hypertension ; rebound hypertension ; withdrawal symptoms ; plasma noradrenaline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Nine patients with essential hypertension completed a clinical trial designed to study the effects and side effects of administration and withdrawal of guanfacine (2 mg tds) and methyldopa (250 mg tds) on blood pressure, heart rate, and plasma noradrenaline. The study was of randomised doubleblind crossover design with two active therapy phases of eight weeks each, preceded by an initial 4 week placebo phase, separated by an intermediate 2 week placebo phase, and followed by a final 2 week placebo phase. Patients took bendrofluazide 5 mgs daily throughout the entire trial, during both active and placebo periods. Each patient was admitted to hospital at the end of the 8 week active treatment phases, so that the effects of drug withdrawal on blood pressure, heart rate, plasma noradrenaline and side reactions, could be closely observed and monitored. The main conclusions from analysis of the results were that: 1. The hypotensive efficacy of guanfacine and methyldopa was very similar in the doses used, each of the two drugs lowering the supine mean arterial pressure by about 15 mm Hg and the supine diastolic pressure by about 10 mm Hg. 2. The frequency of side effects was greater with guanfacine than with methyldopa. 3. There was no signficant early rebound phenomenon after withdrawal of either methyldopa or guanfacine. 4. There was tendency for the blood pressure to rise slowly and marginally above initial placebo values, 2 weeks after cessation of guanfacine treatment though this was not significant. It was however, accompanied by a significant increase in plasma noradrenaline at 2 weeks. This was not seen 2 weeks after cessation of methyldopa. There was no single incidence of worrying rebound hypertension or withdrawal symptoms either early or late in any patient following cessation of methyldopa or guanfacine.
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 21 (1982), S. 287-291 
    ISSN: 1432-1041
    Schlagwort(e): tolmesoxide ; hypertension ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Tolmesoxide is a new, direct-acting vasodilator drug for use in the management of both hypertension and cardiac failure. In 6 essential hypertensives inadequately controlled by combined β-blocker and diuretic therapy (average supine blood pressure 178/103 mm Hg) the addition of tolmesoxide (300–900 mg daily) was associated with a significant improvement in blood pressure control (average supine blood pressure 161/89 mmHg). The effect of food on the pharmacokinetics and pharmacodynamics of tolmesoxide have also been studied because, particularly at higher doses, the drug has been associated with upper gastrointestinal upset and it has been empirically recommended that it be taken with food. The blood pressure and heart rate responses were not significantly different when tolmesoxide was taken fasting or with food. Food resulted in a significant reduction in the peak plasma tolmesoxide concentration (2.14 µg/ml compared to 2.97 µg/ml) and a significant increase in the time to reach peak plasma concentration (1.67 h compared to 0.63 h). Although there was no impairment of its hypotensive effect, food significantly altered the pharmacokinetics of tolmesoxide and may therefore be useful in reducing the gastrointestinal disturbance associated with its use. In the treatment of inadequately controlled hypertension, tolmesoxide has a limited role as an alternative vasodilator.
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 21 (1982), S. 363-367 
    ISSN: 1432-1041
    Schlagwort(e): labetalol ; clonidine ; hypertension ; dose titration ; bendrofluazide ; side effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The antihypertensive effect of labetalol (L) was compared with that of clonidine (C) in a randomized cross-over study in 17 hypertensive outpatients on bendrofluazide (B). After treatment for two weeks with B (5 mg qd), either L (100 mg tid) or C (0.1 mg tid) was given and their doses were titrated at 2-weekly visits until normotension was achieved, or intolerable side-effects occurred. The treatment with B and L or C was then continued in a cross-over fashion for two 6-week periods, with 3 week diuretic washouts and subsequent dose-titration periods between the treatment periods. At the end of B, the supine blood pressure (BP) was 156/101, and at the end of B + L and B + C it was 136/91 (p〈0.001) and 137/91 (p〈0.001), respectively, pooling the data from both periods. At the end of B, the standing BP was 155/115, and at the end of B + L and B + C 134/100 (p〈0.001) and 139/106 (p〈0.001), respectively. The mean daily doses required were L 476mg and C 0.335 mg. On a weight basis, labetalol had about 1/1400 of the potency of clonidine. 12 patients complained of tiredness and dry mouth on clonidine and 2 patients of unsteadiness on labetalol. Labetalol caused a psoriasiform rash on the hands in one patient and limb weakness in one patient.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 22 (1982), S. 7-14 
    ISSN: 1432-1041
    Schlagwort(e): prazosin ; baroreflexes ; hypertension ; reflex tachycardia ; alpha adrenergic blockade ; dopamine-beta-hydroxylase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Prazosin is a post synaptic alpha adrenergic blocker effective in hypertension, whose hypotensive effect is unaccompanied by reflex tachycardia or hyperreninemia, nor by other evidence of increased sympathetic activity. We studied the baroreceptor reflex arc as a potential mediator of these effects. Twenty-two essential hypertensive men were treated with prazosin alone versus placebo, and experienced a blood pressure fall (from 114.8±3.6 down to 101.1±2.5 mm Hg,p〈0.005) unaccompanied by any change in heart rate, plasma renin activity, or several other indices of sympathetic nervous system activity (plasma dopamine-β-hydroxylase activity; urinary excretion of free catecholamines and vanillyl mandelic acid; allp〉0.1). Concomitant with the blood pressure fall, there was a significant depression of baroreflex arc sensitivity, from 11.4±2.0 ms/mmHg down to 6.6±1.9 ms/mmHg (p〈0.05), without an associated change in cardiac vagal inhibition (291.2±46.2 versus 300.3±19.2 ms,p〉0.1). Baroreflex arc sensitivity depression may in part explain the lack of reflex sympathetic outflow noted during prazosin treatment of hypertension.
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 22 (1982), S. 197-201 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; oxprenolol ; indomethacin ; drug interaction ; hypotensive effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A double-blind, cross-over study in 16 patients with essential hypertension was carried out, to evaluate any possible interference by indomethacin, a known prostaglandin-synthetase inhibitor, with the antihypertensive effect of oxprenolol, a non-selective beta-adrenoceptor blocking agent. Both indomethacin and oxprenolol, as well as the two drugs combined, inhibited plasma renin activity; no change was found in urinary sodium excretion or body weight. Oxprenolol alone caused a highly significant decrease in the systolic (−10.4 mmHg,p〈0.001), diastolic (−7.4 mmHg,p〈0.001) and mean (−7.7 mmHg,p〈0.01) blood pressures, whereas indomethacin did not influence blood pressure. When the two drugs were given in combination, blood pressure decreased (systolic: −5.9 mmHg; diastolic: −4.0 mmHg; mean: −4.6 mmHg), but the changes induced in blood pressure were reduced by about 50% when compared with those in the oxprenolol alone period. The data show that indomethacin seems to interfere with the antihypertensive effect of oxprenolol, by an action which may be due to the inhibition of prostaglandin synthesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 20 (1981), S. 163-168 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; captopril ; cardiac output ; extracellular fluid volume ; renin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effects of captopril 450 mg/day for 4 weeks on blood pressure, heart rate, cardiac output and extracellular fluid volume were compared in severe, often drug-resistant hypertension (n=23), mild to moderate hypertension associated with renal artery stenosis (n=10) and mild to moderate essential hypertension (n=20). Plasma renin in the three groups was 52±19, 58±17 and 20±4 µU/ml (mean ± SEM), respectively. Blood pressure fell by 18±4%, 21±2% and 18±1%. The pressure drop was mainly due to a fall in peripheral vascular resistance. Addition of the diuretic hydrochlorothiazide (25–100 mg/day) caused a further fall in resistance. Despite the vasodilator effect of captopril, reflex cardiostimulation and reactive fluid retention were not observed. In severe hypertension, captopril alone was more effective in lowering blood pressure than combined diuretic-betablocker-vasodilator therapy. Moreover, cardiac output in these patients was higher and resistance was lower after captopril than during combined treatment. Thus, captopril was capable of normalising the abnormal haemodynamic state in patients with essential hypertension, and in hypertension associated with renal artery stenosis. Despite marked differences in pre-treatment plasma renin, the effects of captopril on systemic haemodynamics were similar in all the patients.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    ISSN: 1432-1041
    Schlagwort(e): vasodilator ; hypertension ; haemodynamic effects ; renal plasma flow ; renal tubular function ; plasma renin activity ; aldosterone ; Ro 12-4713
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Selected cardiovascular and endocrine effects of the new oral vasodilator Ro 12-4713 have been evaluated in an acute single dose study. In five patients with essential hypertension, Ro 12-4713 caused a dose-dependent decrease in supine and upright blood pressure and an increase in heart rate. Initial effects occurred one to 2 h after drug ingestion and maximal effects were noted after five hours and persisted for at least 8 h. Blood pressure was normalized, and the antihypertensive and chronotropic effects persisted for 24 h after a dose of about 300 mg/1.73 m2. Plasma and urinary norepinephrine and plasma renin levels tended to be raised, whereas plasma and urinary epinephrine and plasma aldosterone did not change. Changes in supine heart rate were inversely correlated with changes in mean blood pressure (r=−0.60; P〈0.02), and positively with those in plasma norepinephrine (r=0.55; P〈0.05) and renin (r=0.62, P〈0.01); changes in supine plasma renin level were also inversely correlated with those in mean blood pressure (r=−0.65; P〈0.01), and positively with those in plasma norepinephrine (r=0.58; P〈0.05). 24 h-urinary sodium excretion was significantly (P〈0.001) decreased; it was positively correlated with mean blood pressure (r=0.51; P〈0.05) and inversely with supine plasma renin activity (r=−0.63; P〈0.01). In six normal subjects and six patients with essential hypertension, effective renal plasma flow and the renal clearance of sodium, potassium, calcium and uric acid were not significantly altered five hours after a dose of Ro 12-4713 of about 250 mg/1.73 m2; glomerular filtration rate tended to be slightly decreased, and filtration fraction was significantly (P〈0.05) reduced in the hypertensive patients. At the same time blood pressure was decreased and plasma norepinephrine (P〈0.01) and renin (ns) were slightly increased in both groups. Ro 12-4713 in a single oral dose of about 300 mg appeared to be a potent, long acting, hypotensive vasodilator.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 22 (1982), S. 495-499 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; cyclothiazide ; hydrochlorthiazide ; thiazide diuretics ; potassium-sparing diuretics ; saluretic effect ; hypokalaemia ; hyperuricaemia ; amiloride
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The antihypertensive, saluretic and hypokalaemic effects of a small dose of cyclothiazide (2.5 mg daily) were compared with those of a conventional dose of an hydrochlorthiazide-amiloride hydrochloride combination (50+5 mg daily). Both preparations were given to 13 patients with mild (WHO I) hypertension in a cross-over manner for six weeks, with an intervening wash-out phase of three weeks. The antihypertensive efficacy of cyclothiazide was well comparable to that of the hydrochlorthiazide-amiloride combination, although cyclothiazide tended to inhibit renal sodium reabsorption less than the combination. Cyclothiazide tended to cause hypokalaemia, apparently due to increased potassium loss, but with the present dosage none of the 13 patients developed marked hypokalaemia (serum potassium less than 3.3 mmol/l). Both drugs led to a comparable increase in serum urate concentration. Neither of the preparations affected creatinine or free-water clearance. The results suggest that even in relatively small doses thiazides effectively decrease blood pressure, and combining thiazides with potassium-sparing diuretics is advantageous only in patients with marked hypokalaemia and its associated risks.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 24 (1983), S. 157-161 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; cadralazine ; single dose ; dose response curve ; hypotensive action ; prolonged effect ; side effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Cadralazine (ISF 2469) was administered to 24 hypertensive patients in single oral doses of 7.5, 10, 15, 20 and 30 mg, according to a single-blind, placebo-controlled, within-patient change-over design. The study was done in 2 stages: in the first a range including the upper and lower doses was studied (7.5, 15, 30 mg and placebo), and in the second the range of doses was restricted (10, 15, 20 mg and placebo). The drug produced a significant decrease in blood pressure in the supine and standing positions. The decrease became clinically important starting from the 15 mg dose. Its action was still significant 12 h after administration. A significant increase in heart rate was also observed. All the effects were correlated with the dose. Side effects occurred mainly after the 30 mg dose. Thus, cadralazine, in a single oral dose in man, showed good antihypertensive activity starting from the 15 mg dose, and its effect was dose-related, slow in onset and long-lasting.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 24 (1983), S. 217-220 
    ISSN: 1432-1041
    Schlagwort(e): metoprolol ; pregnancy ; hypertension ; kinetics ; pre-eclampsia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The disposition of oral metoprolol was studied in 5 women during the last trimester of pregnancy and 3 to 5 months after delivery. After a single oral dose of 100 mg the individual peak plasma concentration in the pregnant state was only 20–40% of that after pregnancy. The plasma half-lives of metoprolol were about the same during (average 1.3 h) and after pregnancy (average 1.7 h). By contrast, the area under the plasma concentration versus time curve was much smallerduring (mean 262 nmol/l×h) thanafter (mean 1298 nmol/l×h) pregnancy, resulting in an average apparent oral clearance (Clo) of metoprolol that was 4.4times higher during (362 ml×kg−1 body-weight×min−1) than after pregnancy. The increased Clo in pregnancy is assumed to be due to enhanced hepatic metabolism of the drug. The possible clinical consequence of the difference in the disposition of metoprolol is discussed.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 24 (1983), S. 307-314 
    ISSN: 1432-1041
    Schlagwort(e): endralazine ; hypertension ; blood pressure ; heart rate ; renal clearance ; plasma renin activity ; plasma aldosterone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effects of endralazine, a new antihypertensive hydrazinopyridazine derivative, on heart rate, mean blood pressure (mBP), glomerular filtration rate (GFR), effective renal plasma flow (CPAH), urine volume (V), the clearance of Na, K, urea (Ur) and uric acid (UA), plasma renin activity (PRA) and plasma aldosterone (PA) were studied in hypertensive patients after a single oral dose of 10–15 mg, and after 8–17 days of treatment with daily doses of 15–90 mg. In the acute experiments, heart rate increased by 27%, mBP decreased on average by 17% and GFR by 33% and CPAH fell by only 5%. Urine volume and electrolyte clearance were also depressed. There was a significant increase in PRA and PA. The fall in GFR correlated directly with mBP, CPAH and the product (mBP×CPAH). The logarithms of the Na clearance and V were correlated with GFR and mBP. The logarithms of the fractional excretion of Na and water also correlated with mBP, suggesting that tubular reabsorption of sodium and water may be affected by change in mBP. The fractional potassium excretion correlated directly with CPAH and ln PA. In contrast, on sustained daily treatment, mBP was less depressed (9%), but GFR increased strikingly by 27% and CPAH by 46%. The body weight increased by 4.5% as a consequence of salt and water retention. GFR was correlated with CPAH, the product (mBP×CPAH) and the increase in body weight. Thus, the improvement in GFR and effective renal plasma flow observed under these conditions may be due, in part, to volume expansion. However, a direct renal vasodilating effect of the drug appears to be the more important determinant.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 24 (1983), S. 579-583 
    ISSN: 1432-1041
    Schlagwort(e): indapamide ; hypertension ; baroreflex ; vascular reactivity ; heart rate ; blood pressure change
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of chronic treatment with indapamide on blood pressure (BP), baroreceptor sensitivity (BRS) and vascular reactivity (VR) were investigated in 10 patients with essential hypertension. After 3 months of therapy with indapamide 2.5 mg/d the mean arterial pressure (MAP) had decreased from 135±6 to 112±2 mmHg (p〈0.001); the heart rate (HR) had not changed, VR had decreased from 6.1±1.2 to 4.8±1.8 (pg·min·kg)−1 (p〈0.05), and BRS had increased from 8.3±3.7 to 12.2±5.3 ms/mmHg (p〈0.005), with a leftshift of the relationship between BP and heart period. An inverse correlation was found between the pre-treatment systolic blood pressure and the change in baroreceptor sensitivity after indapamide (r=0.59; p〈0.05). In conclusion, chronic treatment with indapamide enhances BRS and resets the reflex. The resetting may account for the lack of tachycardia at rest observed after treatment with indapamide. The mechanism by which indapamide interferes with the baroreceptor reflex requires further investigations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 143-144 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; nifedipine ; plasma concentration ; blood pressure response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    ISSN: 1432-1041
    Schlagwort(e): furosemide ; hypertension ; plasma renin activity ; plasma adrenaline ; plasma noradrenaline ; body fluid loss ; diuretic response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary To evaluate the role of adrenergic mechanisms in the acute response of renin to furosemide, plasma renin activity (PRA) and plasma catecholamine concentrations were measured for 3 h after i.v. administration of furosemide 1 mg/kg to 8 patients with mild essential hypertension. Furosemide induced a prompt and long-lasting increase in renin, with PRA more than doubled at all times. The increase in PRA within the first 30 min paralleled the peak increases in urinary water and sodium flow rates, and significant decreases in plasma volume and central venous pressure. There was no change in plasma catecholamine concentrations. Plasma noradrenaline was increased significantly at 60 min and adrenaline at 90 min, once furosemide had induced a marked loss of body-fluid and ∼65% decrease in central venous pressure. Both catecholamines remained elevated until the end of the study, whereas urinary water and sodium flow rates had returned to their pre-treatment values by 150 min. Mean blood pressure was essentially unchanged throughout the study, whereas heart rate increased significantly after 90 min. The findings suggest that in mildly hypertensive patients adrenergic mechanisms are not involved in the initial renin response to furosemide, but they come into play later, probably as a result of reflex sympathetic activation triggered by marked volume depletion.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 307-312 
    ISSN: 1432-1041
    Schlagwort(e): ketanserin ; hypertension ; blood pressure ; plasma noradrenaline ; exercise ; orthostatic reflexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Ketanserin is a new, specific serotonin receptor blocking agent, which causes vasodilatation, presumably by an action on the vascular wall. The antihypertensive response to ketanserin 40 mg twice daily as monotherapy was assessed in 8 patients with essential hypertension. The investigation was an 8 week, double-blind, cross over study, which also included measurements during isometric (handgrip) and dynamic exercise (bicycle ergometry), as well as determination of plasma catecholamines and ketanserin. Ketanserin caused a reduction of supine and standing systolic and diastolic blood pressure (BP) during rest and a slight bradycardia. Although there was attenuation of the pressor response to handgrip, treatment with ketanserin did not really affect the changes in BP or heart rate during exercise, i.e. the base-line differences remained the same. There was no significant correlation between the effect on BP and the plasma level of ketanserin. The changes in BP produced by ketanserin showed little correlation with the initial levels of plasma catecholamines or with alterations in those levels. Although the results did not indicate direct interference by ketanserin with sympathetic tone, the lack of reflexogenic tachycardia, as well as the lack of increase in plasma noradrenaline during hand grip, indicates at least some modulation of autonomic function. It is concluded that ketanserin lowers BP in essential hypertension without interference with cardiovascular reflexes during standing or exercise, and that the compound may offer an alternative approach in the treatment of hypertension.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 571-575 
    ISSN: 1432-1041
    Schlagwort(e): beta-blocker ; felodipine ; calcium antagonist ; hypertension ; vasodilator ; side effects ; plasma levels ; metoprolol ; propranolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In a double-blind, cross-over trial, 10 men with primary hypertension, not adequately controlled with a β-blocker alone, were also given felodipine or placebo for periods of one week. Placebo was administered single-blind for 2 weeks and 1 week, respectively, before randomization and between treatments. The dose of felodipine ranged from 6.25 mg to 25 mg. The addition of felodipine resulted in a pronounced (20%), statistically significant reduction in blood pressure (BP) and a small but significant increase in heart rate (HR). The effects were seen within 1–2 h and were maximal after 3–4 h. During steady state treatment the duration of BP reduction was at least 12 h. No orthostatic reaction was seen. There was a significant correlation between the plasma concentration of felodipine and change in BP. The most frequently reported side-effects were headache and ankle oedema, the latter probably being due to pronounced pre-capillary vasodilatation. There was no weight increase and thus no indication of general water retention. No clinically significant change in laboratory variables and no influence on the P-Q time were seen. Thus, felodipine in combination with a β-blocker seems to be a useful addition to the treatment of hypertensive patients whose BP is not adequately controlled with a β-blocker alone.
    Materialart: Digitale Medien
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  • 96
    ISSN: 1432-1041
    Schlagwort(e): prizidilol ; hypertension ; exercise test ; beta-blockade ; vasodilatation ; haemodynamic effects ; vascular tone ; muscle blood flow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Fourteen men with moderately severe essential hypertension were treated with prizidilol hydrochloride 400–700 mg once daily (mean±S.D. 612±56 mg/day). The study was open and ambulatory, with an initial placebo period followed by dose titration of prizidilol. Prior to treatment and during optimal control of blood pressure cardiovascular adaptation was examined in a submaximal exercise test. Plethysomographic assessment of vascular flow, resistance and tone in the calf musculature during supine rest and during maximal vasodilatation was also performed. A highly significant reduction in systolic (from 164±4.5 to 141±2.7 mmHg; p〈0.001) and diastolic blood pressure (from 105±1.6 to 87±1.3 mmHg; p〈0.001) at supine rest was noted during therapy with prizidilol. There was no significant change in heart rate. Systolic pressure in the standing position was reduced (from 159±4.2 to 139±2.9 mmHg; p〈0.001) and so was the diastolic pressure (from 111±2.5 to 95±1.9 mmHg; p〈0.001). The heart rate in the standing position was significantly increased compared to supine rest in the placebo period and during optimal treatment with prizidilol. The β-adrenoceptor blocking properties of prizidilol were apparent as a reduction in the exercise-induced heart rate response at even the lowest work load. During prizidilol therapy an increase in resting calf muscle blood flow was found from 3.1±1.5 ml/min·100 ml to 4.3±2.1 ml/min·100 ml (p〈0.025). Vascular resistance and vascular tone were significantly reduced. No change regarding blood flow or resistance during maximal vasodilatation was noted. It is considered that prizidilol has a clear antihypertensive effect combining β-receptor blocking and vasodilator properties.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 26 (1984), S. 309-313 
    ISSN: 1432-1041
    Schlagwort(e): clonidine ; hypertension ; therapeutic window ; steady state concentration ; pharmacokinetics ; cardiovascular effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Clonidine was given orally as monotherapy in increasing daily doses from 3.1 to 25.7 µg/kg to patients with essential hypertension (n=6). When a steady state concentration in plasma was reached at each dose level, the blood pressure (BP) and heart rate were measured during a dosage interval. Effect time — plasma concentration data were submitted to nonlinear regression analysis, which showed that the observed BP effects could be dissociated into depressor and pressor components. A window for the antihypertensive effect was established. At a plasma clonidine concentration of 0.65±0.07 ng/ml 50% of the maximal depressor effect was found, and it was only separated by a factor of 2 from the half maximal pure pressor concentration in plasma. No relationship between the change in heart rate and the plasma clonidine was observed. The findings strengthen the importance of close monitoring of clonidine therapy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 26 (1984), S. 331-334 
    ISSN: 1432-1041
    Schlagwort(e): metoprolol ; oxprenolol ; hypertension ; beta-blockers ; HDL-cholesterol ; intrinsic sympathomimetic activity ; cardioselectivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The aim of the present study was to evaluate whether a reduction in HDL-cholesterol is peculiar to non cardioselective beta blockers or whether it is also produced by cardioselective beta1-blockers. 16 patients with primary arterial hypertension on a balanced isocaloric diet were given oxprenolol 120 to 240 mg/day or metoprolol 100 to 200 mg/day in a random cross-over study. No significant change was observed after either treatment in fasting blood glucose, serum total cholesterol and triglycerides. HDL-cholesterol concentration was significantly decreased on metoprolol, from 41 to 36 mg/dl (p〈0.05), while oxprenolol did not affect it at all. The difference might depend on intrinsic sympathomimetic activity which is possessed by oxprenolol and which metoprolol lacks.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 26 (1984), S. 549-553 
    ISSN: 1432-1041
    Schlagwort(e): pafenolol ; hypertension ; antihypertensive therapy ; beta1-blocking agent ; exercise tests ; plasma levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Pafenolol, a new selective adrenergic beta1-blocking agent, has been tested for the first time in 6 hypertensive patients. After single oral doses of pafenolol 25 to 100 mg, there was a marked reduction in heart rate and systolic blood pressure during exercise tests. These effects were dose dependent. A significant positive correlation was found between the reduction in heart rate during exercise and the plasma level of pafenolol 5 hours after drug intake (correlation coefficient r=0.94). Side effects were mild and seemed to be dose dependent. It is concluded that this new beta1-blocking agent was effective in reducing blood pressure and was well tolerated.
    Materialart: Digitale Medien
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  • 100
    ISSN: 1432-1041
    Schlagwort(e): etozolin ; ozolinone ; furosemide ; hypertension ; renin ; catecholamines ; chronic renal failure ; steady state kinetics ; plasma levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect on urinary electrolyte excretion, renin release and plasma norepinephrine of single oral doses of 400 mg etozolin (E) and of 40 mg furosemide (F) were studied in hypertensive patients with normal (n=6) and impaired kidney function (n=6). E caused a marked saluresis up to 24 hours, showing its long duration of action. F, however, displayed a brief, brisk peak diuresis, followed by a rebound from the 4th to the 24th hours. The brisk peak diuresis induced by F was associated with pronounced release of renin, almost twice that induced by E. In chronic renal failure the renin release in relation to the magnitude of the diuresis was increased, i.e. the sensitivity of these patients to changes in water homeostasis was increased. E and F stimulated the sympathetic system to roughly the same extent. Patients with essential hypertension had higher plasma levels of norepinephrine than hypertensive patients with chronic renal failure. In addition, hypertensive patients with normal renal function (n=4) and varying degrees of renal impairment (n=11) were also given 400 mg daily for 2 weeks. Effects on blood pressure and electrolyte homeostasis were monitored, as well as the plasma kinetics of metabolite I, ozolinone. At the end of the 2 week treatment E had significantly lowered systolic (−12 mm Hg) and diastolic (−9 mm Hg) blood pressure, and had produced a significant loss of body weight, without altering plasma electrolytes or blood chemistry. There was no accumulation of the effective metabolite ozolinone under conditions of severe impairment of kidney function. It is concluded that E can effectively control high blood pressure in patients with normal and impaired kidney function. Its effective metabolite ozolinone did not accumulate in chronic renal failure.
    Materialart: Digitale Medien
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