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  • Ultrastructure  (585)
  • Drosophila  (161)
  • Springer  (745)
  • Cambridge University Press
  • 1985-1989  (340)
  • 1970-1974  (405)
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  • 1
    Electronic Resource
    Electronic Resource
    Distribution and conservation of the foldback transposable element inDrosophila (1989)
    Springer
    Journal of molecular evolution 28 (1989), S. 220-224 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Foldback element ; Transposable element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Foldback elements are a family of transposable elements described inDrosophila melanogaster. The members of this dispersed repetitive family have terminal inverted repeats that sometimes flank a central region. The inverted repeats of all the family members are homologous. The study of the distribution and conservation of the foldback elements in differentDrosophila species shows that this distribution is different from that of the hybrid dysgenesis systems (PM and IR). Sequences homologous to foldback elements were observed by Southern blots and in situ hybridization in all species of themelanogaster subgroup and in some species of themontium andtakahashii subgroups. The element was probably already present before the radiation of these subgroups. No evidence of horizontal transmission of the foldback element could be observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102479
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  • 2
    Electronic Resource
    Electronic Resource
    Two different sets of cis elements regulate scute to establish two different sensory patterns (1989)
    Springer
    Development genes and evolution 198 (1989), S. 227-232 
    Details
    ISSN: 1432-041X
    Keywords: Campaniform sensilla ; Drosophila ; Achaete-scute complex ; Cis regulatory sites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analysed the role of the achaete-scute gene complex in the development of the pattern of campaniform sensilla on the wing blade of Drosophila. We show that the complete pattern results from the superimposition of two independent subpatterns, one of which depends on the achaete gene and the other on scute. The scute subpattern comprises several clusters of sensilla, most of which seem to require the presence of control regions located upstream of the transcribed region. This is in contrast with the pattern of scute-dependent bristles, most of which depends on control elements located downstream of the transcribed region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375909
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  • 3
    Electronic Resource
    Electronic Resource
    Pattern triplications following genetic ablation on the wing ofDrosophila (1989)
    Springer
    Development genes and evolution 198 (1989), S. 65-77 
    Details
    ISSN: 1432-041X
    Keywords: Cell communication ; Pattern formation ; Cell differentiation ; trans-regulatory genes ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects ofpolyhomeotic (ph) mutants in imaginal cells have been studied in a clonal analysis. Clones of cells, homozygous forph, sort-out after a few divisions, probably as a consequence of modified cell affinities. The dorso-ventral margin of the wing has special characteristics that retard this phenomenon. The formation and exclusion of a clone of 8–16 cells affect the polarity of the wild-type neighbour cells and can provoke pattern triplications. The results suggest that a defect in intercellular communication prevents the wild-type cells from maintaining coordinated positional information. The cells react by regenerative growth, and reorganize into a new pattern. The pleiotropic phenotypes ofph mutants are explained according to a common hypothesis aboutph + function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447741
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  • 4
    Electronic Resource
    Electronic Resource
    Yolk organelles and their membranes during vitellogenesis ofXenopus oocytes (1989)
    Springer
    Development genes and evolution 198 (1989), S. 92-102 
    Details
    ISSN: 1432-041X
    Keywords: Vitellogenesis ; Xenopus oocyte ; Yolk-platelet membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The yolk platelets ofXenopus laevis have been studied by thin-section and freeze-fracture electron microscopy to characterize the boundary membrane during yolk formation. Throughout vitellogenesis, large yolk platelets are in close contact with smaller nascent yolk organelles. Two types of primordial yolk platelets (I and II) have been discriminated. After membrane fusion these precursors can be completely incorporated into the main body of existing platelets, numerous yolk crystals then merge and form one uniformly stratified core. Lipid droplets are tightly attached to the membrane at all developmental stages of yolk platelets. A direct connection of endoplasmic reticulum to the membranes of yolk platelets was not observed. On freezeetching replicas, yolk-platelet membranes present fracture faces with intramembranous particles (IMP) of various sizes and a heterogeneous distribution of approximately 200–600 IMP/μm2 at the E face, and 1200–2100 IMP/μm2 at the P face. Again, this presentation of the membrane exhibits neither anastomoses to the endoplasmic reticulum, nor caveolae that exclude the uptake of yolk-containing vesicles into these yolk organelles. Proteinaceous yolk platelets tend to fracture along their periphery through the superficial layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447744
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  • 5
    Electronic Resource
    Electronic Resource
    Proximal-distal pattern formation inDrosophila: graded requirement forDistal-less gene activity during limb development (1989)
    Springer
    Development genes and evolution 198 (1989), S. 157-169 
    Details
    ISSN: 1432-041X
    Keywords: Distal less ; Limb development ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of all of the adult limbs inDrosophila depends upon the activity of theDistal-less gene. We report here the phenotypic characterization of a number of hypomorphicDistal-less alleles which indicates that there is a graded requirement forDistal-less activity in the developing limbs. Previous analysis of genetically mosaic animals indicated that cells in the early primordia of the limb imaginal dises possess a graded proximal-distal positional information which depends on the presence of theDistal-less gene for its expression. Taken together these data suggest thatDistal-less may directly encode the graded positional information that is required to organise the proximal-distal axis of the developing limbs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02438941
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  • 6
    Electronic Resource
    Electronic Resource
    Follicle cell development is partly independent of germ-line cell differentiation in Drosophila oogenesis (1989)
    Springer
    Development genes and evolution 198 (1989), S. 185-190 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Oogenesis ; Follicle cells ; Egg shell ; Ovarian tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The developmental potential of the cells of the somatic follicular epithelium (follicle cells) was studied in mutants in which the differentiation of the germ-line cells is blocked at different stages of oogenesis. In two mutants, sn 36a and kelch, nurse cell regression does not occur, yet the follicle cells around the small oocyte continue their normal developmental program and produce an egg shell with micropylar cone and often deformed operculum and respiratory appendages. Neither the influx of nurse cell cytoplasm into the oocyte nor the few follicle cells covering the nurse cells are apparently required for the formation of the egg shell. In the tumor mutant benign gonial cell neoplasm (bgcn) the follicle cells can also differentiate to some extent although the germ-line cells remain morphologically undifferentiated. Vitelline membrane material was synthesized by the follicle cells in some bgcn chambers and in rare cases a columnar epithelium, which resembled morphologically that of wild-type stage-9 follicles, formed around the follicle's posterior end. The normal polarity of the follicular epithelium that is characteristic for mid-vitellogenic stages may, therefore, be established in the absence of morphologically differentiating germ-line cells. However, the tumorous germ-line cells do not constitute a homogeneous cell population since in about 30% of the analyzed follicles a cell cluster at or near the posterior pole can be identified by virtue of its high number of concanavalin A binding sites. This molecular marker reveals an anteroposterior polarity of the tumorous chambers. In follicles mutant for both bgcn and the polarity gene dicephalic the cluster of concanavalin A-stained germ-line cells shifts to more anterior positions in the follicle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375904
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of microbial floras on the distributions of five domestic Drosophila species across fruit resources (1989)
    Springer
    Oecologia 78 (1989), S. 533-541 
    Details
    ISSN: 1432-1939
    Keywords: Drosophila ; Microbial associations ; Resource partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distributions of five Drosophila species and four components of the microflora have been compared across a total of 48 traps baited with four different fruit and vegetable substrates in two domestic compost heaps in Canberra (Australia). Large and consistent differences are found, both among the Drosophila and among the microbial classes, in their distributions across traps baited with different substrates. Moreover the distribution of each Drosophila species shows a unique set of strong associations with the microbial distributions. Thus the distributions of both D. simulans and D. melanogaster are found to be strongly negatively correlated with the abundance of bacteria while D. simulans is also strongly positively correlated with the titre of fermenter yeasts. D. immigrans is strongly positively correlated both with bacteria and with non-fermenter yeasts. D. hydei is positively correlated with nonfermentery yeasts and D. busckii is negatively correlated with fermenter yeasts. Moulds are the only microbial class not consistently associated with the distribution of any of the Drosophila species. The correlations with the other microbial classes are sufficient to explain the majority of the abundance differences of the Drosophila species among the trap types. It is therefore proposed that the clear partitioning of the fruit resources by the Drosophila is due to their differing primary interactions with the microflora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378745
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  • 8
    Electronic Resource
    Electronic Resource
    An electron microscope study on in vitro parthenogenesis in sunflower (1989)
    Springer
    Sexual plant reproduction 2 (1989), S. 154-166 
    Details
    ISSN: 1432-2145
    Keywords: Helianthus annuus ; Unfertilized ovule culture ; Parthenogenesis ; Ultrastructure ; Proembryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron microscope studies have been conducted on the parthenogenesis induced by in vitro culture of unfertilized ovules of sunflower (Helianthus annuus). In comparison with the state of the egg prior to inoculation, some eggs 5 days after culture show striking ultrastructural changes, which include, among others, nuclear migration, an increase in the number and activity of the organelles, a loss of polarity and wall formation at the chalazal end of the cell. Most of these changes are similar to those that occur normally in the zygote, indicating that parthenogenic development has been triggered in these eggs. Such eggs have been termed activated and are presumed to be capable of undergoing parthenogenesis. The parthenogenic proembryos which result share some features in common with zygotic proembryos. In addition, some parthenogenic proembryos exhibit unique properties not found in zygotic proembryos. These include embryos that consist of two parts differing markedly in density, an inversion of polarity, the frequent occurrence of autophagic vacuoles, the thickening of cell walls, a centripetal growth mode of wall formation, the appearance of an incomplete cell wall, free nuclear division, amitosis and degeneration. We believe that these ultrastructural peculiarities are the effects of in vitro culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192762
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  • 9
    Electronic Resource
    Electronic Resource
    The ultrastructure of polymorphic pollen grains of Canna indica L. (1989)
    Springer
    Sexual plant reproduction 2 (1989), S. 193-198 
    Details
    ISSN: 1432-2145
    Keywords: Polymorphism ; Ultrastructure ; Pollen grains ; Canna indica L ; Tannin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our investigations on Canna indica L. indicate that the pollen of this species is polymorphic: there are two types of pollen — a larger type and a comparatively smaller type. Transmission electron microscopy (TEM) revealed the presence of small vacuoles containing tannic substances in the generative cell (GC) of the larger grains: the GC of the mature grain contained a higher quantity of tannins than the GC of the immature grain. Mitochondria, lipid bodies, rough endoplasmic reticulum (RER) and microtubular bundles were present in the cytoplasm of the GC. Numerous mitochondria, lipid bodies and plastids were also present in the vegetative cell (VC), with the mitochondria clustered around the vegetative nucleus. The plastids were observed to be associated with the RER cisterns. During the maturation process, the number of starch grains contained in the plastids decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192766
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  • 10
    Electronic Resource
    Electronic Resource
    Lanthanum mimicks the trp photoreceptor mutant of Drosophila in the blowfly Calliphora (1989)
    Springer
    Journal of comparative physiology 166 (1989), S. 179-187 
    Details
    ISSN: 1432-1351
    Keywords: Blowfly ; Drosophila ; Photoreceptor ; Lanthanum ; trp mutant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of lanthanum on the light response of blowfly (Calliphora erythrocephala) photoreceptors was studied. The electrophysiological behaviour of the photoreceptors in the presence of La can be summarized as follows: 1. Upon long stimulation the photoreceptors responded with a ‘transient receptor potential’, i.e. the cells depolarized at the onset of the stimulus and then repolarized to (or below) the resting potential. This effect was dependent on stimulus intensity and occurred only at high intensities. During illumination membrane noise was reduced. 2. The light-induced changes in membrane potential were paralleled by changes in membrane resistance. 3. The time course of the receptor response was slowed down. 4. Light adaptation led to an increase in response latency. 5. The recovery of the receptor response after light adaptation was slowed down. 6. The sensitivity of the receptor cells measured by the response to short light stimuli was reduced. In summary, the electrophysiological behaviour of Calliphora photoreceptors in the presence of La was very similar to that of the photoreceptors of the trp (transient receptor potential) mutant of Drosophila melanogaster. This result suggests that La and trp mutation affect the same cellular processes in the photoreceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193462
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  • 11
    Electronic Resource
    Electronic Resource
    Immunogold localization of coenzyme F420-reducing formate dehydrogenase and coenzyme F420-reducing hydrogenase in Methanobacterium formicicum (1989)
    Springer
    Archives of microbiology 151 (1989), S. 307-313 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium formicicum ; Formate dehydrogenase ; F420-hydrogenase ; Immunogold ; Ultrastructure ; Methanogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructural locations of the coenzyme F420-reducing formate dehydrogenase and coenzyme F420-reducing hydrogenase of Methanobacterium formicicum were determined using immunogold labeling of thin-sectioned, Lowicryl-embedded cells. Both enzymes were located predominantly at the cell membrane. Whole cells displayed minimal F420-dependent formate dehydrogenase activity or F420-dependent hydrogenase activity, and little activity was released upon osmotic shock treatment, suggesting that these enzymes are not soluble periplasmic proteins. Analysis of the deduced amino acid sequences of the formate dehydrogenase subunits revealed no hydrophobic regions that could qualify as putative membrane-spanning domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406556
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  • 12
    Electronic Resource
    Electronic Resource
    The ultrastructure of chemolithoautotrophic Gallionella ferruginea and Thiobacillus ferrooxidans as revealed by chemical fixation and freeze-etching (1989)
    Springer
    Archives of microbiology 151 (1989), S. 245-251 
    Details
    ISSN: 1432-072X
    Keywords: Gallionella ferruginea ; Thiobacillus ferrooxidans ; Iron bacteria ; Chemolithoautotrophy ; Ultrastructure ; Freeze-etching ; Cell wall organization ; Intracytoplasmic membranes ; Carboxysomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By using sodium thioglycolate to dissolve the high amount of excreted stalk material in axenic cultures of the chemolithoautotrophic iron bacterium Gallionella ferruginea, the ultrastructure of Gallionella cells from pure cell suspensions could be studied without any loss of viability or disturbance by dense ferric stalk fibers, and compared with Thiobacillus ferrooxidans, also grown chemolithoautotrophically with ferrous iron as energy source. Both organisms were chemically fixed or freeze-etched. Particular structural differences between these iron-bacteria could be ascertained. G. ferruginea possesses intracytoplasmic membranes and soluble d-ribulose-1,5-bisphosphate-carboxylase, whereas T. ferrooxidans contains carboxysomes but no intracytoplasmic membranes; Gallionella forms poly-β-hydroxybutyrate and glycogen as storage material; T. ferrooxidans produces only glycogen. Both organisms also differ from each other with respect to the freeze fracture behaviour of the cell envelope layers. Whereas the cells of T. ferrooxidans exhibit a characteristic double cleavage, exposing the plasmic fracture face and exoplasmic fracture face of the outer membrane and cytoplasmic membrane, the exceptionally thin multilayered cell envelope of G. ferruginea revealed a particularly intimate association between the layers, resulting in a visualisation of the supramolecular organisation of only the inner fracture face of the cytoplasmic membrane. The results are discussed predominantly in relation to the extremely distinct environments of both organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413137
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  • 13
    Electronic Resource
    Electronic Resource
    Microscopic examination and fatty acid characterization of filamentous bacteria colonizing substrata around subtidal hydrothermal vents (1989)
    Springer
    Archives of microbiology 152 (1989), S. 64-71 
    Details
    ISSN: 1432-072X
    Keywords: Thiothrix sp. ; Beggiatoa sp. ; Sulfideoxidizing ; Polyunsaturated ; Fatty acids ; Inclusions ; Sheath ; Southern California ; Ultrastructure ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microscopic examination of the whitish mat that covered the substrata around subtidal hydrothermal vents at White Point in southern California revealed a “Thiothrix-like” bacterium containing sulfur inclusions as the dominant filamentous form in this microbial community. The matlike appearance developed as a result of the closely-packed manner inwhich the basal ends of the filaments were anchored to the substrate. The dominant phospholipid fatty acids of these filaments (16:0, 16:1w7c, 18:0, 18:1w7c) were similar to those recovered from a sample of Beggiatoa isolated from a spring in Florida. Filaments from both sources contained small quantities of C18 and C20 polyunsaturated fatty acids, as well. A larger but less abundant sheathless, filamentous form, which also contained sulfur inclusions and displayed a cell wall structure similar to a previously described Thioploca strain, also colonized the substrata around the subtidal mat. The preservation methods used in the preparation of thin-sections of the subtidal mat material were found to be inadequate for defining some key cellular structures of the large filaments. Nevertheless, the results demonstrate that the filamentous bacteria comprising the microbial mat in the vicinity of the subtidal vents exhibit some of the features of the free-living filamentous microorganisms found in deep-water hydrothermal areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447013
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  • 14
    Electronic Resource
    Electronic Resource
    Food preferences and nematode parasitism in mycophagousDrosophila (1989)
    Springer
    Ecological research 4 (1989), S. 209-218 
    Details
    ISSN: 1440-1703
    Keywords: Annual life cycle ; Drosophila ; Fungus preference ; Nematode parasitism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Food preferences and nematode parasitism were studied in natural populations of mycophagousDrosophila in and near Sapporo, northern Japan. Species which preferred fresh mushrooms showed species-specific responses toPleurotus mushrooms:D. pirka bred only onPleurotus cornucopiae, D. trivitata onP. cornucopiae andP. ostreatus, D. trilineata on these twoPleurotus mushrooms and some other mushrooms, whileD. sexvittata bred on a wide variety of mushrooms but seldom onPleurotus mushrooms. Species which preferred decayed mushrooms (D. quadrivittata, D. histrioides, D. testacea and species of thequinaria species-group) showed host preferences different from those of the above species. The rate of parasitism by nematodes was generally higher in species which prefer decayed mushrooms than in species which prefer fresh mushrooms. Among species which prefer fresh mushrooms, onlyD. trilineata was parasitized frequently by nematodes. It was not clear what factors determine the rate of parasitism in these mycophagousDrosophila. D. pirka, D. trivittata andD. trilineata passed through three or four generations per year and entered reproductive diapause in early September in and near Sapporo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02347153
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  • 15
    Electronic Resource
    Electronic Resource
    Two nearby sites bind zen protein independently (1989)
    Springer
    Molecular and cellular biochemistry 90 (1989), S. 27-35 
    Details
    ISSN: 1573-4919
    Keywords: zerknullt gene ; homeobox protein ; Drosophila ; filter binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The region upstream from the zerknullt (zen) gene contains three sites that specifically bind the zen protein product of the gene. Evidence for these binding sites was obtained by the filter binding technique and the DNase footprinting technique. The filter binding technique was used to scan various segments of DNA for the presence of possible specific binding sites. Segments that were selectively retained by the filter binding technique invariably contained one or more specific binding sites according to the DNase footprinting technique. Two of the zen protein binding sites were spaced only 30 base pairs apart. These sites could be separated without any loss in their specific binding properties. It is concluded that these two sites function independently in the binding of zen protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225218
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  • 16
    Electronic Resource
    Electronic Resource
    Comparative analysis of glue proteins in theDrosophila nasuta subgroup (1989)
    Springer
    Biochemical genetics 27 (1989), S. 507-520 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) ; glue proteins ; glycosylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of theDrosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins inD. n. nasuta andD. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas inD. melanogaster and inD. hydei the fraction is only 32 and 35%, respectively.
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    URL: http://dx.doi.org/10.1007/BF00553628
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  • 17
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    Electronic Resource
    Comparative analysis of glue proteins in theDrosophila nasuta subgroup (1989)
    Springer
    Biochemical genetics 27 (1989), S. 507-520 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) ; glue proteins ; glycosylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of theDrosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins inD. n. nasuta andD. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas inD. melanogaster and inD. hydei the fraction is only 32 and 35%, respectively.
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    URL: http://dx.doi.org/10.1007/BF02396148
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  • 18
    Electronic Resource
    Electronic Resource
    Rapid enzyme kinetic assays of individualDrosophila and comparisons of field-caughtD. melanogaster andD. simulans (1989)
    Springer
    Biochemical genetics 27 (1989), S. 263-277 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; kinetic plate reader ; enzyme polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Techniques for performing numerous enzyme kinetic assays with minimum time and effort would be valuable to studies of the evolutionary genetics of metabolic control and the quantitative genetics of determinants of kinetic parameters. Microtiter plate readers have been used for a variety of repetitious analytical techniques, and instruments are available that can take repetitive readings with sufficient speed to perform kinetic assays. The ability of these instruments to assay rapidly the kinetic properties of small samples makes them potentially useful for a number of problems in population genetics. While the ability to handle large numbers of samples is very attractive, the small sample volumes and optical imprecision of microtiter plates result in some sacrifice in accuracy. This paper presents methods for performing kinetic assays on individual field-caughtDrosophila, quantifies the precision of these methods, and characterizes differences amongDrosophila melanogaster andD. simulans from samples caught in California and Pennsylvania. Comparisons between field-caught and laboratory rearedD. melanogaster show that most of the characters are very similar, with the exception of αGPDH, which has a threefold higher mean activity among field-caught flies. The phenotypic correlations are presented with a brief discussion of their relevance to assessing the evolution of metabolic control of these enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554162
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  • 19
    Electronic Resource
    Electronic Resource
    Thealdox-2 locus ofDrosophila melanogaster also affects sulfite oxidase and molybdenum metabolism (1989)
    Springer
    Biochemical genetics 27 (1989), S. 99-118 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; aldox-2 ; molybdoenzymes ; sulfite oxidase ; molybdenum ; tungsten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mutation at thealdox-2 locus inDrosophila melanogaster affects the specific activities of four molybdoenzymes differentially during development. Sulfite oxidase activity is normal during late larval and pupal stages but is reduced during early adult stages inaldox-2 organisms. There was complete concordance among the effects ofaldox-2 on sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and pyridoxal oxidase, when 38 stocks were analyzed which were derived from single recombination events betweenc andpx, markers which flankaldox-2. Several different biochemical analyses indicate that the active molybdoenzymes present in thealdox-2 strain are normal with respect to size, shape,pH-activity profile,K m , and molecular weight. Significant differences were found between thealdox-2 strain and the OR control strain in their responses to dietary Na2MoO4 and Na2WO4. The mutant strain is much more resistant to the effects of dietary Na2WO4 and much more responsive to the administration of Na2MoO4 than the OR control strain when these effects are quantitated by measurements of molybdoenzyme specific activities. This evidence suggests that thealdox-2 + gene product has a molybdenum binding site which can also bind tungsten and that this site is altered in the mutant strain. The hypothesis presented explains the observed effects of thealdox-2 mutation and relates them to the other mutations reported in this gene-enzyme system.
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    URL: http://dx.doi.org/10.1007/BF00563021
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  • 20
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    High-resolution analysis of locomotor activity rhythms indisconnected, a visual-system mutant ofDrosophila melanogaster (1989)
    Springer
    Behavior genetics 19 (1989), S. 529-542 
    Details
    ISSN: 1573-3297
    Keywords: Drosophila ; circadian clock ; ultradian oscillations ; disconnected mutant ; visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Free-running locomotor activity and eclosion rhythms ofDrosophila melanogaster, mutant at thedisconnected (disco) locus, are substantially different from the wild-type phenotype. Initial periodogram analysis revealed little or no rhythmicity (Dushayet al., 1989). We have reanalyzed the locomotor activity data using high-resolution signal analysis (maximum-entropy spectral analysis, or MESA). These analyses, corroborated by autocorrelograms, uncovered significant residual circadian rhythmicity and strong ultradian rhythms in most of the animals tested. In this regard thedisco mutants are much like flies expressing mutant alleles of theperiod gene, as well as wild-type flies reared throughout life in constant darkness. We hypothesize that light normally triggers the coupling of multiple ultradian oscillators into a functional circadian clock and that this process is disrupted indisco flies as a result of the neural lesion.
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    URL: http://dx.doi.org/10.1007/BF01066252
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    Effect of rate of inbreeding on inbreeding depression in Drosophila melanogaster (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 123-127 
    Details
    ISSN: 1432-2242
    Keywords: Inbreeding depression ; Drosophila ; Natural selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This experiment was designed to study the relationship between rate of inbreeding and observed inbreeding depression of larval viability, adult fecundity and cold shock mortality in Drosophila melanogaster. Rates of inbreeding used were full-sib mating and closed lines of N=4 and N=20. Eight generations of mating in the N=20 lines, three generations in the N=4 lines and one generation of full-sib mating were synchronised to simultaneously produce individuals with an expected level of inbreeding coefficient (F) of approximately 0.25. Inbreeding depression for the three traits was significant at F=0.25. N=20 lines showed significantly less inbreeding depression than full-sib mated lines for larval viability at approximately the same level of F. A similar trend was observed for fecundity. No effect of rate of inbreeding depression was found for cold shock mortality, but this trait was measured with less precision than the other two. Natural selection acting on loci influencing larval viability and fecundity during the process of inbreeding could explain these results. Selection is expected to be more effective with slow rates of inbreeding because there are more generations and greater opportunity for selection to act before F=0.25 is reached. Selection intensities seem to have been different in the three traits measured. Selection was most intense for larval viability, less intense for fecundity and, perhaps, negligible at loci influencing cold shock mortality.
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    URL: http://dx.doi.org/10.1007/BF00292326
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    Heterosis in crosses between lines of Drosophila melanogaster selected for adaptation to different environments (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 253-259 
    Details
    ISSN: 1432-2242
    Keywords: Heterosis ; Selection ; Drosophila ; Genotype x environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments were designed to examine whether heterosis would occur in crosses of Drosophila melanogaster populations adapted to 18 °C or 28 °C environments. Crosses were examined in parental environments, an intermediate environment (23 °C) and a mixed environment (alternating 18°/28°C). Parental populations did not show divergence for larval viability, cold shock or high temperature mortalities when tested in a common environment. However, the 28 °C population was less fecund than the 18 °C population, but had higher larval competitive ability and higher adult longevity. Heterosis for viability, cold shock mortality and high temperature mortality occurred in crosses between a population adapted to 18 °C and another adapted to 28 °C, but not in crosses between two populations adapted to the same temperature. The results suggest that, in the absence of drift, heterosis is expected in crosses between lines or populations with different histories of selection but not between lines with the same selection histories.
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    URL: http://dx.doi.org/10.1007/BF00266195
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    Ultrastructural changes induced by precocene II and 3,4-dihydroprecocene II in the corpora allata of Blattella germanica (1989)
    Springer
    Cell & tissue research 258 (1989), S. 91-99 
    Details
    ISSN: 1432-0878
    Keywords: Corpora allata ; Ultrastructure ; Precocenes ; Juvenile hormone ; Blattella germanica (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural studies on corpora allata (CA) from different stages during the first gonadotropic cycle of the cockroach Blattella germanica have shown well defined changes which have a correspondence with oocyte length, CA volume and juvenile hormone (JH) biosynthesis. The most significant variations concern the mitochondria and the endoplasmic reticulum. Topically applied precocene II (P II) at a dose of 200 ⧎g induced a transient arrest of CA function, although cytotoxic effects were occasionally observed. When CA were maintained in vitro with 10-3 M of P II, a relationship between the time of treatment (3, 6 or 9 h) and the intensity of the effects was apparent. The 9-h treatment led to an irreversible inhibition of JH production which parallels the severe damages observed in the CA (membrane lysis, nuclear pyknosis, vacuolization). Equivalent studies performed with the chroman derivative 3,4-dihydroprecocene II (DHP II) showed that it is less active than P II. Only treatments as severe as 12 h of incubation with a 10-3 M concentration elicited cytotoxic effects which could be due to radical species involved in the in situ oxidative bioactivation of DHP II. Thus, this compound could be regarded as a new type of pro-allatocidin.
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    URL: http://dx.doi.org/10.1007/BF00223148
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    Structural features of the epididymis in a dasyurid marsupial (Antechinus stuartii) (1989)
    Springer
    Cell & tissue research 258 (1989), S. 203-210 
    Details
    ISSN: 1432-0878
    Keywords: Epididymis ; Histology ; Ultrastructure ; Antechinus stuartii (Marsupialia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ductus epididymidis of the marsupial mouse Antechinus stuartii was divided into caput, corpus, and caudal regions using several constant morphological landmarks. Tubule diameter and epithelial height increased gradually from caput to cauda. In contrast, the surface area of the lumen of the ductus epididymidis increased to a maximum in the distal caput region, but decreased markedly in the distal cauda in association with characteristic changes in lumen shape (from circular to slit-shaped) and epithelial height. Epithelial cells of the ductus epididymidis were generally similar in structure to those described in other mammalian species. Principal and basal cells were common throughout the epithelium. Clear and mitochondria-rich cells were also identified, but occurred less frequently. Regional variations in cell ultrastructure were observed only in principal cells. Numerous vesicular inclusions occurred in the apical cytoplasm of cells in caput segments, membrane-bounded, electron-dense bodies were common in distal corpus regions, and a brush border of microvilli characterized the luminal surface of principal cells in caudal segments. Sperm index increased in the proximal caput, declined to basal levels in the distal caput and proximal corpus, and then increased to a maximum in segment 9 of the distal corpus and remained at about this level throughout the cauda epididymidis. Nuclear rotation, loss of cytoplasmic droplets, and other sperm maturational changes were observed along the epididymis. Discarded cytoplasmic droplets collected in large masses interspersed between aggregates of spermatozoa throughout the distal regions of the duct. There was no evidence of phagocytosis by principal cells of cytoplasmic droplets. The epididymis of A. stuartii differs from that of other mammals. The unusual caudal region, which has little storage capacity for sperm, is an unusual adaptation in a species in which the male is known to be polygamous.
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    URL: http://dx.doi.org/10.1007/BF00223158
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    System-specific distribution of zinc in the chick brain (1989)
    Springer
    Cell & tissue research 258 (1989), S. 247-257 
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    ISSN: 1432-0878
    Keywords: Zinc ; Timm method ; Ultrastructure ; Synapses ; Avian brain ; Domestic fowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The brain of young domestic chicks was investigated using a Timm sulfide silver method. Serial Vibratome sections were analyzed under the light microscope, and the localization of zinc-positive structures in selected areas was determined at the ultrastructural level. Both strong and differential staining was visible in the avian telencephalon whereas most subtelencephalic structures showed a pale reaction. The highest staining intensity was found in the nonprimary sensory regions of the telencephalon such as the hyperstriatum dorsale, hyperstriatum ventrale, hippocampus, palaeostriatum augmentatum, lobus parolfactorius and caudal parts of neostriatum. There was an overall gradient of staining intensity in neostriatal areas from rostral to caudal with the heaviest zinc deposits in the caudal neostriatum. Primary sensory projection areas, such as the ectostriatum (visual), hyperstriatum intercalatum superius (visual), nucleus basalis (beak representation), the input layer L2 of the auditory field L and the somatosensory area rostral to field L were selectively left unstained. Fiber tracts throughout the brain were free of zinc deposits except for glial cells. In electron micrographs of stained regions, silver grains were localized in some presynaptic boutons of asymmetric synapses (Gray type I), within the cytoplasm of neuronal somata and sporadically in the nucleus. The possible involvement of zinc in synaptic transmission and other processes is discussed.
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    URL: http://dx.doi.org/10.1007/BF00239445
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    Effects of long-term hypergastrinaemia on the ultrastructure of enterochromaffin-like cells in the stomach of the rat, hamster and guinea pig (1989)
    Springer
    Cell & tissue research 256 (1989), S. 247-257 
    Details
    ISSN: 1432-0878
    Keywords: Enterochromaffin-like cells ; Ultrastructure ; Hypertrophy ; Hypergastrinaemia ; Gastrin infusion ; Omeprazole ; Rat (Sprague Dawley) ; Syrian hamster ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present report describes the ultrastructure of the enterochromaffin-like (ECL) cells in the stomach of the rat, hamster and guinea pig, and the ultrastructural consequences of long-term hypergastrinaemia evoked either by continuous infusion of synthetic human (Leu15)-gastrin-17 for 4 weeks (rats) or by daily treatment with large doses of the antisecretory agent omeprazole for 2–10 weeks (rats, hamsters and guinea pigs). As a result, the ECL cells increased greatly in size (maximal effect after 2 weeks of omeprazole treatment, no further gain in size after 4 or 10 weeks). Also the endoplasmic reticulum and Golgi area were enlarged. The most conspicuous feature of the ECL cells is the cytoplasmic vesicles, which are of varying size and either devoid of a dense core or with a small, often eccentrically located dense core. The vesicles probably represent the main storage site of the secretory products of the ECL cell. In addition, the cytoplasm contains granules, which differ from the vesicles in that they possess a more or less electron-dense core, surrounded by a narrow halo. The size of the vesicles ranged from small to very large, while the granules were uniformly small. Many vesicles were seen to lie very close together, some displaying an irregular outline (vacuole-like vesicles), at times giving the impression that they were undergoing fusion. The profile size (median value) of the vesicles was unaffected by gastrin infusion for 4 weeks. However, there was a tendency to a relative increase in the number of very small vesicles. In contrast, the vesicles became larger during the omeprazole treatment. Also, the number of vesicles that seemed to be engaged in fusion increased after omeprazole treatment but not after gastrin infusion. The observations support the view that ECL cells are influenced by gastrin. The effects of gastrin infusion and of omeprazole treatment on ECL cell ultrastructure were not completely identical. It cannot be excluded that the omeprazole-evoked achlorhydria evokes effects unrelated to those of hypergastrinaemia on the ECL cells, or that endogenous gastrins may evoke effects that are in some ways distinct from those of synthetic human (Leu15)-gastrin-17. Alternatively, the additional effects seen after long-term omeprazole treatment may reflect simply the duration of the hypergastrinaemic stimulus.
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    URL: http://dx.doi.org/10.1007/BF00218882
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    Morphological changes in the junctional complex of cells in the arachnoid layer of the rat after cold injury (1989)
    Springer
    Cell & tissue research 256 (1989), S. 303-307 
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    ISSN: 1432-0878
    Keywords: Arachnoid cells ; Tight and gap junctions ; Cold injury ; Ultrastructure ; Freeze-fracture technique ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The junctional complexes of cells in the outer arachnoid layer overlying the cerebral cortex of 2-week-old rats were examined with freeze-fracture electron microscopy up to 60 min after transcranial cold injury to the dorsal surface of the brain. Within 30 min after injury, areas of gap and tight junctions with morphological features characteristic of junction formation and/or junction disruption were found scattered among normal junctional complexes in some arachnoid cells. Within 60 min after injury, tight junctions with features typical of less leaky zonulae occludentes were present in all arachnoid cells examined. These morphological features include increases in the number of tight junctional strands and the number of strand-to-strand anatomoses. Gap junctions were interspersed among the tight junctional strands, and many were completely encircled by the strands. The increase in the number and complexity of the tight junctional strands in response to brain injury may be the morphological basis for the maintenance of the cerebrospinal fluid-blood dural barrier.
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    URL: http://dx.doi.org/10.1007/BF00218887
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    The effect of low- and high-density lipoprotein cholesterol on steroid hormone production and ACTH-induced differentiation of rat adrenocortical cells in primary culture (1989)
    Springer
    Cell & tissue research 256 (1989), S. 487-494 
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    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Differentiation ; Tissue culture ; Steroids ; Ultrastructure ; Lipoproteins ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We studied the effects of lipoprotein-derived cholesterol on the ACTH-induced differentiation of cultured fetal rat adrenocortical cells. For this purpose human plasma high-density lipoprotein3 (HDL3) or low-density lipoprotein (LDL) was added to culture media devoid of cholesterol, and thereafter the morphological changes in cells were monitored and the amounts of steroids synthesized were measured. It could be demonstrated that, ultrastructurally, upon ACTH-stimulation the adrenocortical cells differentiated into fasciculata-like cells even in the absence of lipoproteins in the culture medium. The addition of either HDL3 or LDL caused an increase in the number and size of cytoplasmic lipid droplets suggesting uptake and deposition of lipoprotein-derived cholesterol into the differentiating cells. The amount of steroids secreted from cells differentiating in media devoid of cholesterol was only half that observed in cells differentiating in serum-supplemented medium. Addition of either HDL3 or LDL increased the ACTH-stimulated steroid synthesis to the levels observed in serum-supplemented medium. This study demonstrates that both HDL3 and LDL are able to provide cholesterol for steroid synthesis accompanying the ACTH-induced differentiation of fetal rat adrenocortical cells.
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    URL: http://dx.doi.org/10.1007/BF00225596
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    The effect of bromocriptine on the intermediate lobe of the rat pituitary: an electron-microscopic, morphometric study (1989)
    Springer
    Cell & tissue research 255 (1989), S. 405-410 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary gland, pars intermedia ; Bromocriptine ; Secretory granules ; Golgi apparatus ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological effect of chronic synthetic and secretory inhibition of the intermediate lobe of the rat pituitary induced by bromocriptine treatment was studied using morphometric techniques in combination with electron microscopy. On the basis of granule diameters, a heterogeneous cell population was shown in the normal intermediate lobe. Bromocriptine treatment did not induce any change in the volume fraction, number or location of electron-dense secretory granules. Instead, there was a shift toward a more homogeneous cell population containing smaller granules, the mean granule volume being reduced by ∼30%. The volume fraction of electron-lucent granules or vacuoles was markedly reduced, indicating a functional significance of these organelles. The volume of the Golgi apparatus was not significantly altered, but the number of condensing granules within the Golgi area was reduced. The volume of the intermediate lobe was decreased, apparently due to a decrease in the mean cell volume.
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    URL: http://dx.doi.org/10.1007/BF00224124
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    Distribution of peroxidase and iodination activity in the endostyles of Oikopleura albicans and Oikopleura longicauda (Appendicularia, Chordata) (1989)
    Springer
    Cell & tissue research 255 (1989), S. 505-510 
    Details
    ISSN: 1432-0878
    Keywords: Endostyle ; Peroxidase cytochemistry ; Autora diography ; Ultrastructure ; Oikopleura albicans, Oikopleura longicauda (Appendicularia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oikopleura albicans and O. longicauda belong to the two subgenera Vexillaria and Coecaria, respectively. The morphology and ultrastructure of their endostyles were investigated with conventional microscopic procedures as well as with DAB cytochemistry and 125I autoradiography at both light- and electron-microscopic levels. As expected, the general morphology of these endostyles is similar to all hitherto examined endostyles. They possess a ventral portion consisting of alternating glandular and ciliated cell zones, probably serving food capture, and a dorsal region, the corridor. Autoradiographic grains were found mainly in the corridor lumen associated with the apical surface of the two central rows of corridor cells. The same cells also gave strong positive reactions for peroxidase, the iodinating enzyme. Peroxidase activity was found in the apical plasma membrane as well as in the nuclear envelope, rough endoplasmic reticulum, Golgi area and cytoplasmic vesicles. Definitive conclusions concerning an apical uptake and subsequent release into the body fluid of iodinated material could not be made from the present experiments. Our investigations indicate that the two central rows of corridor cells in both subgenera of oikopleurids constitute the protothyroid region, possibly homologous to the vertebrate thyroid gland.
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    Morphogenesis of rat cranial meninges (1989)
    Springer
    Cell & tissue research 257 (1989), S. 207-216 
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    ISSN: 1432-0878
    Keywords: Morphogenesis ; Meninges ; Mesenchyme ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The meninges of albino Wistar rat embryos, aged between the 11th embryonic day (ED) and birth, were sectioned using a specially constructed device. This technique permits optimal microanatomical preservation of all tissues covering the convexity of the brain: skin, muscle, cartilage or bone, and the meninges. At ED11, the zone situated between the epidermis and the brain is occupied by a mesenchymal network. At ED12, part of this delicate network develops as a dense outer cellular layer, while the remainder retains its reticular appearance, thus forming an inner layer (the future meningeal tissue). At ED13, the dura mater starts to differentiate. At ED14, the bony anlage of the skull can be identified, and along with the proceeding maturation of dura mater some fibrillar structures resembling skeletal muscle fibers appear in the developing arachnoid space. At ED15–17, a primitive interface zone — dura mater/ arachnoid — is formed, comprised by an outer electronlucent and an inner electron-dense layer marking the outer aspect of the arachnoidal space. At ED18–19, the innermost cellular row of the inner durai layer transforms into neurothelium, which is separated from the darker arachnoidal cells by an electron-dense band. The arachnoidal trabecular zone with the leptomeningeal cells is formed at ED19. By the end of the prenatal period (ED20–21), its innermost part organizes into an inner arachnoidal layer and an outer and inner pial layer. The results from this study indicate (i) that dura mater and leptomeninges develop from an embryonic network of connective tissue-forming cells, and (ii) that the formation of cerebrospinal fluid (CSF)-containing spaces accompanies the differentiation of the meningeal cellular layers.
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    Terminal processes of serotonin neurons in the caudal spinal cord of the molly, Poecilia latipinna, project to the leptomeninges and urophysis (1989)
    Springer
    Cell & tissue research 255 (1989), S. 619-625 
    Details
    ISSN: 1432-0878
    Keywords: Serotonin-containing cells ; Urophysis ; Spinal Cord ; Ultrastructure ; Leptomeninges ; Poecilia latipinna (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The caudal neurosecretory complex of poeciliids has previously been shown to be innervated by extranuclear and intrinsic serotonergic projections. In the present study, immunohistochemical techniques were used to characterize fibers originating from serotonin neurons intrinsic to the caudal spinal cord. Bipolar and multipolar neurons were oriented ventromedially, and contained numerous large granular vesicles. Three types of serotonergic fibers were distinguished based on their distribution and morphology. Intrinsic Type-A fibers branched into varicose segments near the ventrolateral surface of the spinal cord and contacted the basal lamina beneath the leptomeninges. Type-B fibers coursed longitudinally to enter the urophysis, where they diverged and terminated around fenestrated capillaries. Labelled vesicles in Type-A and Type-B terminals were the same size as those in labelled cells and in unlabelled neurosecretory terminals in the urophysis. Type-C small varicose fibers branched within the neuropil of the caudal neurosecretory complex. Serotonin may be secreted into the submeningeal cerebrospinal fluid, the urophysis, and the caudal vein by Type-A and Type-B fibers, whereas, Type-C fibers may be processes of serotonergic interneurons in the neuroendocrine nucleus. The possibility that urotensins I and II or arginine vasotocin were colocalized in the processes of the intrinsic serotonin neurons was investigated immunohistochemically. The negative results of these experiments suggest that serotonin-containing neurons may represent a neurochemically distinct subpopulation in the caudal neurosecretory complex.
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    URL: http://dx.doi.org/10.1007/BF00218799
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    Neural activity pattern is not necessary for the development of adult ultrastructure in katydid (Neoconocephalus robustus) singing muscles (1989)
    Springer
    Cell & tissue research 255 (1989), S. 641-644 
    Details
    ISSN: 1432-0878
    Keywords: Insect muscle ; Denervation ; Ultrastructure ; Development, ontogenetic ; Neoconocephalus robustus (Insecto)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The singing muscles of the katydid Neoconocephalus robustus develop adult ultrastructure late in the last nymphal instar and during the first few days of adult life. The ultrastructural changes during early adulthood were not affected by unilateral axotomy shortly after the adult molt. Both denervated and innervated muscles developed adult proportions of mitochondria, myofibril, and sarcoplasmic reticulum and transverse tubules.
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    URL: http://dx.doi.org/10.1007/BF00218802
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    The three-dimensional structure of the zona pellucida in growing and atretic ovarian follicles of the mouse (1989)
    Springer
    Cell & tissue research 257 (1989), S. 247-253 
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    ISSN: 1432-0878
    Keywords: Zona pellucida ; Ovarian follicles ; Atresia ; Ultrastructure ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study provides further details on the fine-structural three-dimensional architecture of the zona pellucida (ZP) in growing and atretic follicles of mice by use of ruthenium red in combination with the detergents Triton X100 and saponin. These detergents were used for extraction of the “soluble” fraction of the zonal proteins in an attempt to expose the “structural” zonal glycoproteins, which in turn can be viewed as minute three-dimensional networks upon transmission- and scanning electron-microscopic examination. By use of these methods, the ZP of growing follicles appeared to be formed by interconnected filaments which also bind to globular structures building up a three-dimensional lattice. In contrast, the ZP of stage I as well as other (II and III) stages of atretic follicles showed a structure characterized by the presence of closely packed granules connected with short filaments to form a close-mesh reticulum. This structural change of the ZP, which in the present study is also associated with the disappearance of “gap junctions” within the granulosa and cumulus cell population, might represent one of the early events involved in the onset of atresia. These changes, most probably depending on an altered secretory activity of both oocytes and follicle cells, might lead to a degradation of the ZP network structure and to its subsequent increased density (condensation). All these morphodynamic events eventually contribute to a sequestration of the oocyte in the early stage of atresia.
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    URL: http://dx.doi.org/10.1007/BF00261827
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    Smooth muscle fiber types and a novel pattern of thick filaments in the wing of the pteropod mollusc Clione limacina (1989)
    Springer
    Cell & tissue research 257 (1989), S. 405-414 
    Details
    ISSN: 1432-0878
    Keywords: Mollusc ; Ultrastructure ; Musculature ; Hydroskeleton ; Retraction reflex ; Clione limacina (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Wing (parapodial) retraction in the pteropod mollusc Clione limacina is a reflex triggered by tactile stimulation. Light and transmission electron microscopy revealed three groups of smooth muscles in the wing hemocoel that participate in retraction movements: transverse, longitudinal, and dorsoventral. Among these, two subtypes of muscle cells were identified. The first (type A) appears in all three groups and forms a well-organized lattice-like structure. The second (type B) is the major component of transverse muscles and runs in one direction only. Quantitative ultrastructural comparisons of dimensions, abundance, and organization of dense bodies, thick and thin filaments, membrane invaginations, sarcoplasmic reticulum, and mitochondria suggest that type A cells are able to contract and relax more quickly with less endurance whereas type B cells are capable of generating stronger contractions with more endurance and slower relaxation speed. Furthermore, type A cells have a unique pattern of thick filament organization, here referred to as pseudosarcomeres. The roles played by the different cell types in wing retraction are discussed.
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    Ultrastructural changes in granule cell somata and mossy fibers of the rat hippocampus during picrotoxin-induced convulsions (1989)
    Springer
    Cell & tissue research 255 (1989), S. 261-267 
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    ISSN: 1432-0878
    Keywords: Hippocampus ; Mossy fibers ; Picrotoxin ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural changes in hippocampal granule cells, mossy fibers and mossy fiber boutons were examined following the administration of picrotoxin in adult rats. Generalized seizures occurred within 5–10 min after the intraperitoneal injection of picrotoxin. The electron-microscopic examination of hippocampal tissues from rats that had been perfused with fixative during the seizure revealed that the large dense-core vesicles increased in number and accumulated on the presynaptic membranes of mossy fiber boutons; some of these vesicles appeared to be fused with the membranes, and omega-shaped exocytotic profiles were frequently seen. Furthermore, greatly increased numbers of coated vesicles (60–90 nm in diameter) were observed on the maturing faces of Golgi fields of granule cells. Thus, our study not only indicates an increased incidence of exocytosis of large dense-core vesicles during picrotoxin-induced seizures, but also suggests that these vesicles are replaced in excess from the perikaryon of the granule cell.
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    URL: http://dx.doi.org/10.1007/BF00224107
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    Vestigal mutants of Drosophila melanogaster live better in the presence of aminopterin: Increased level of dihydrofolate reductase in a mutant (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 475-480 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Vestigial ; Dihydrofolate reductase ; Aminopterin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Vestigial (vg) mutants of Drosophila melanogaster are characterized by atrophied wings. In this paper we show that: (1) aminopterin an inhibitor of dihydrofolate reductase (DHFR) and fluorodeoxyuridine (FUdR), an inhibitor of thymidylate synthetase induce nicks in the wings of wild-type flies and phenocopies of the vg mutant phenotype when vg/+ and vg B/+ flies are reared on these substances (vgB is a deficiency of the vg locus). Only thymidine and thymidylate can rescue the flies from the effect of aminopterin. We propose that the vg phenotype is due to a decrease in the dTMP pool in the wings. (2) Mutant vg strains yield more offspring on medium containing aminopterin than on normal medium. The resistance of vg larvae to the inhibitor seems specific to the gene. This is the first case of aminopterin resistance in living eucaryotes. In contrast sensitivity of the vg larvae to FUdR is observed. (3) An increase in the activity and amount of DHFR is observed in mutant strains as compared with the wild-type flies. Our data suggest that the vg + gene is a regulatory gene acting on the DHFR gene or a structural gene involved in the same metabolic pathway.
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    URL: http://dx.doi.org/10.1007/BF00332412
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    Regulatory elements involved in the tissue-specific expression of the yellow gene of Drosophila (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 118-126 
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    ISSN: 1617-4623
    Keywords: Drosophila ; Regulation ; yellow gene ; Germline transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have assessed the DNA sequence requirements for the correct spatial pattern and phenotypic expression of y in the late embryo/larvae. The wild-type larval phenotype requires both the regions between-294 bp and-92 bp and a portion of the intron; the sequence element(s) located within the intron can act in a position independent manner to effect the wild-type larval phenotype. The larval expression pattern was examined by tissue experiments in situ and by staining germline transformants derived from various y/lacZ fusion constructs. The larval expression of y is restricted to the mouthparts, microsetae and anal plates. While the-495 bp to+194 bp region alone cannot effect a wild-type larval expression pattern, this region in conjunction with the intron appears to be sufficient to drive β-gal expression in an essentially wild-type pattern. Our data further suggest that the-294 bp to-92 bp region contains elements which specify the larval pattern and that the element(s) in the intron normally act to enhance the level of expression necessary for the wild-type larval phenotype. We also present a phenotypic analysis of the adult cuticle structures of germline transformants derived from a variety of deletion and rearrangement constructs of the y gene. This analysis has revealed several new features associated with the regulation of y expression.
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    URL: http://dx.doi.org/10.1007/BF00330574
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    Search for Drosophila genes encoding a conserved domain present in the achaete-scute complex and myc proteins (1989)
    Springer
    Molecular genetics and genomics 215 (1989), S. 281-285 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; achaete-scute complex ; myc ; Protein domains ; Genomic search
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several genes of the achaete-scute complex (ASC) of Drosophila melanogaster encode a 60 amino acids long conserved domain which shares a significant homology with a region of the vertebrate myc proteins. Based on these results, the existence of a family of Drosophila genes that would share both this conserved domain and the neurogenic function of the AS-C has been postulated. To test this proposal, we have searched a D. melanogaster genomic library with a probe that encodes the conserved domain. Only under very low stringency hybridization conditions, clones not belonging to the AS-C cross-hybridized with the probe. Those that gave the strongest signals were characterized. Sequencing of the cross-hybridizing regions showed that they had no significant homology with the conserved domain, the sequence similarity extending at the most for 37 nucleotides. Although our results do not conclusively disprove the existence of a family of AS-C-like genes, they indicate that the conservation of the domain would be lower than that found for shared motifs in other families of Drosophila developmental genes.
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    The role of kinetosome-associated organelles in the attachment of encysting secondary zoospores ofSaprolegnia ferax to substrates (1989)
    Springer
    Protoplasma 149 (1989), S. 163-174 
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    ISSN: 1615-6102
    Keywords: Adhesion ; Carbohydrates ; Exocytosis ; K-bodies ; Lectins ; Saprolegnia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron and fluorescence microscopy were used to identify organelles involved in attachment of secondary zoospores ofSaprolegnia ferax as they were transformed into secondary cysts. When secondary zoospores were exposed to 1.0% peptone in the absence or presence of a substrate, they began to encyst. If substrates were present when encystment was induced, the groove surface of the secondary zoospores adhered to them. The first event in attachment was secretion of contents of the kinetosome-associated organelle (K-body), which was typically oriented with the tubule-filled cavity positioned toward the cell surface of the groove region in the zoospore. The tubules which contained carbohydrates became coarsely granular, the matrix became more fibrous, and the shell remained along the membrane concavity that was formed as the K-body fused with the plasma membrane. Five minutes later, a cyst coat appeared, and cysts were not readily dislodged from a substrate. The concavity was no longer found, presumably because it had evaginated; but a layered pad of adhesion material was between the cyst coat and substrate. The layers of the adhesion pad corresponded to the structure of the matrix of K-bodies. As with the tubules of the K-body, the coarsely granular portion at the edge of the pad stained for carbohydrates. Similarly, the lectins WGA and GS-II labeled with fluorescein stained the rim of the adhesion pad on cysts, indicating the presence of glycoconjugates containing N-acetylglucosamines. Because globular areas near the kinetosomes and groove of zoospores (where K-bodies were located) also bound WGA and GS-II, K-bodies contained the same carbohydrates as the adhesion pad. We conclude that K-bodies function in the attachment of encysting zoospores to substrates as the cell differentiates. The tubular portion of the K-body matrix contains carbohydrates which might assist in the adhesion process.
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    The cytoskeletal involvement in cellularization of theDrosophila melanogaster embryo (1989)
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    Protoplasma 150 (1989), S. 83-95 
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    ISSN: 1615-6102
    Keywords: Drosophila melanogaster embryo ; Cellularization ; Cleavage furrow ; Ultrastructure ; Cytoskeleton ; Mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distribution and arrangement of cytoskeletal components in the early embryo ofDrosophila melanogaster were examined by thin-section electron microscopy to elucidate their involvement in the formation of the cellular blastoderm, a process called cellularization. During the final nuclear division in the cortex of the syncytial blastoderm bundles of astral microtubules were closely associated with the surface plasma membrane along the midline where a new gutter was initiated. Thus the new gutter together with the pre-formed ones compartmentalized the embryo surface to reflect underlying individual daughter nuclei. Subsequently such gutters became deeper by further invagination of the plasma membrane between adjacent nuclei to form so-called cleavage furrows. Nuclei simultaneously elongated in the direction perpendicular to the embryo surface and numerous microtubules from the centrosomes ran longitudinally between the nucleus and the cleavage furrow. Microtubules often appeared to be in close association with the nuclear envelope and the cleavage furrow membrane. The plasma membrane at the advancing tip of the furrow was always undercoated with an electron-dense layer, which could be shown to be mainly composed of 5–6 nm microfilaments. These microfilaments were decorated with H-meromyosin to be identified as actin filaments. As cleavage proceeded, each nucleus with its perikaryon became demarcated by the furrow membrane, which then extended laterally to constrict the cytoplasmic connection between each newly forming cell and the central yolk region. The cytoplasmic strand thus formed possessed a prominent circular bundle of microfilaments which were also decorated with H-meromyosin and bidirectionally arranged, similar in structure to the contractile ring in cytokinesis. These observations strongly suggest that both microtubules and actin filaments play a crucial role in cellularization ofDrosophila embryos.
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    Ultrastructure of the nitrogen-fixing, filamentous, nonheterocystous cyanobacterium,Plectonema boryanum (1989)
    Springer
    Protoplasma 152 (1989), S. 130-135 
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    ISSN: 1615-6102
    Keywords: Plectonema boryanum ; Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Nitrogen starvation ; Immunogold localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of fructose-supplemented and unsupplemented nitrogen-fixing (fix +) and nonfixing (fix −)Plectonema boryanum UTEX 581 cells was examined by transmission electron microscopy. The most prominent structural differences included the arrangement and morphology of the thylakoids and alterations in the appearance of the interthylakoidal spaces. These ultrastructural differences, together with other observations such as glycogen content and presence of nitrogenase (using acetylene reduction assay and immunogold localization), readily distinguished nonfixingP. boryanum from nitrogen-fixing cells.
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    Ultrastructural changes in maturing pollen grains ofApium nodiflorum L. (Apiaceae), with special reference to the endoplasmic reticulum (1989)
    Springer
    Protoplasma 152 (1989), S. 69-76 
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    ISSN: 1615-6102
    Keywords: Apiaceae ; Apium nodiflorum ; Endoplasmic reticulum ; Pollen grain ; Polysaccharide particles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural events in 3-cellular pollen grains ofApium nodiflorum L. are investigated during pollen maturation. Three distinct developmental stages are distinguished from the formation of sperm cells up to anthesis, whereby the rough endoplasmic reticulum (RER) is mainly involved. The most conspicious form is the highly dilated RER in the vegetative cytoplasm of the youngest pollen grains, which changes to vesicular RER in the following stage. In mature pollen grains the RER has a narrow cisternal configuration and often forms stacks. Pollen activation is preceded by the accumulation of polysaccharide particles.
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    The effect of fuel oil on the ultrastructure of the chlorococcal algaScenedesmus armatus (1989)
    Springer
    Protoplasma 151 (1989), S. 47-56 
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    ISSN: 1615-6102
    Keywords: Scenedesmus ; Fuel oil ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Characteristic changes in the ultrastructure of the green algaScenedesmus armatus, grown in batch culture in the presence of aqueous fuel-oil extract (AFOE) have been observed. The changes affected mainly chloroplasts and mitochondria. The regular arrangement of the thylakoid stacks became distorted and the whole chloroplast lobed. Plastoglobules were more numerous in the treated cells than in the controls, especially after long-term exposure to AFOE. The mitochondrial matrix cells exposed to AFOE were more electron-translucent. An increase in the number of small mitochondrial profiles was observed after prolonged treatment with AFOE. The number and size of osmophilic bodies increased markedly in the cytoplasm of the treated cells. The cytochemical reaction of these bodies with Sudan black B indicated their lipid composition. Plasmalemma invagination into the cytoplasm and vacuoles, cytoplasmic “layers”, and an increase in size of the vacuolar compartment were observed in cells exposed to AFOE for a long time. The possibility that detoxification, involving microbody activity, may have occurred inScenedesmus is suggested.
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    Ultrastructural studies of spermatogenesis inAnthocerotophyta V. Nuclear metamorphosis and the posterior mitochondrion ofNotothylas orbicularis andPhaeoceros laevis (1989)
    Springer
    Protoplasma 151 (1989), S. 137-150 
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    ISSN: 1615-6102
    Keywords: Bryophyte ; Notothylas ; Nuclear metamorphosis ; Phaeoceros ; Posterior mitochondrion ; Spermatogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ultrastructural observations reveal that the spermatozoids of the hornwortsNotothylas andPhaeoceros contain two mitochondria and not one as described previously. Mitochondrial ontogeny and nuclear metamorphosis during spermiogenesis in these plants differ from all other archegoniates. The discovery that the posterior region of the coiled nucleus (when viewed from the anterior aspect) lies to the left of the anterior, in striking contrast to the dextral coiling of the nucleus of spermatozoids of other embryophytes, underlines the isolated nature of the hornworts among land plants. As the blepharoplast develops, the numerous ovoid mitochondria initially present in the nascent spermatid fuse to form a single elongated organelle which is positioned subjacent to the MLS and extends down between the nucleus and plastid. At the onset of nuclear metamorphosis, the solitary mitochondrion has separated into a larger anterior mitochondrion (AM) associated with the MLS and a much smaller posterior mitochondrion (PM) adjacent to the plastid. The PM retains its association with the plastid and both organelles migrate around the periphery of the cell as the spline MTs elongate. By contrast, in moss spermatids, where mitochondria undergo similar fusion and division, the AM is approximately the same size as the PM and the latter is never associated with the spline. As in other archegoniates, except mosses, spline elongation precedes nuclear metamorphosis in hornworts. Irregular strands of condensed chromatin compact basipetally to produce an elongated cylindrical nucleus which is narrower in its mid-region. During this process excess nucleoplasm moves rearward. It eventually overarches the inner surface of the plastid and entirely covers the PM.
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    An unusual feature of developing protophloem sieve elements in roots ofTriticum aestivum L. (1989)
    Springer
    Protoplasma 152 (1989), S. 14-21 
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    ISSN: 1615-6102
    Keywords: Differentiation ; Heterochronic lysis ; Polarity ; Root protophloem sieve elements ; Triticum aestivum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Developing protophloem sieve elements in roots of wheat are arranged in single vertical files. In the last immature differentiating sieve element bearing ribosomes the proximal end of the cytoplasm displays a diluted appearance in contrast to the distal end where the cytoplasm exhibits a considerably increased electron density. Differences can also be observed in ribosome quantity, organelle ultrastructure and the time of initiation of cell component degradation, those at the proximal end disorganizing first, suggesting a nonsimultaneous disorganization of the cell components in the two areas. This phenomenon, termedheterochronic lysis, is presumably an expression of an existing polarity not detectable in younger stages, but it might also be the result of an asynchronous enzymatic activity.
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    Ultrastructural responses of tobacco pollen tubes to heat shock (1989)
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    Protoplasma 153 (1989), S. 104-110 
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    ISSN: 1615-6102
    Keywords: Nicotiana sylvestris ; Pollen tube growth ; Heat shock ; Ultrastructure ; Endoplasmic reticulum ; Mitochondria ; Golgi apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of elevated temperatures on semivivo growth and ultrastructure of tobacco pollen tubes was investigated. Tube growth was decreased by about 50% at 35 °C, independent of the duration of treatment, and at 40 °C and above there was no growth of tubes. Heat treatment caused ultrastructural changes like accumulation of membranous materials, concentric stacking of rough endoplasmic reticulum, reduction in vesicle production by dictyosomes, increase in the fenestrated regions of the Golgi cisternae, swelling of mitochondrial saccules and increase in the electron density of the mitochondrial matrix. Furthermore, the dictyosomes of the treated tubes showed significant increase in the number of cisternae from 30 to 45 °C. The temperature induced changes were persistant at least for 24 h in 35 °C grown pollen tubes. The possible reasons for the tube growth inhibition are discussed on the basis of the ultrastructural alterations caused by elevated temperatures.
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    The genetic basis of adaptation to selection for longevity inDrosophila melanogaster (1989)
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    Evolutionary ecology 3 (1989), S. 31-39 
    Details
    ISSN: 1573-8477
    Keywords: Genetic elements ; isozymes ; life span ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Analysis of electrophoretic loci shows that at least four differences exist in isozymes of long- and short-lived populations ofD. melanogaster, descended by selection from a common ancestral stock. Adults of longlived populations differ in gene dosage of phosphoglucomutase (PGM), NAD malate dehydrogenase (MHD), NADP malic enzyme (ME) and by additional mobility variants of glucose-6-phosphate dehydrogenase (G6PD). Larvae, however, differ only by variants of G6PD. The differences in these enzymes, considered together with the greater flight endurance that long-lived populations have shown elsewhere, suggest that increased glycogen synthesis plays a significant role in the improved life span of selected populations. Adaptation to selection for increased life span may, therefore, derive from an improved ability to use dietary sucrose in the media provided. The distribution of electrophoretic loci agrees with the results of a study indicating the position of genetic elements contributing to life span.
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    Evolution of developmental homeostasis inDrosophila mojavensis (1989)
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    Evolutionary ecology 3 (1989), S. 189-201 
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    ISSN: 1573-8477
    Keywords: Developmental homeostasis ; life history traits ; Drosophila ; breeding site variation ; cactus ; Sonoran desert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Variation in life histories among populations of cactophilicDrosophila mojavensis has been hypothesized to be a by-product of a shift to one of two alternate host plants. When cultured on the ancestral and a secondary host cactus, a Baja population expressed shorter development times and smaller thorax sizes than a mainland population, but viability did not differ. Comparisons with all reciprocal F1 and F2 crosses between populations revealed that genetic differences in development time and thorax size were largely additive. Homeostasis in these life history traits was population specific, except for viability. Homeostasis in development time was greater in the Baja population than in the other crosses, suggesting dominance for decreased homeostasis in the mainland population. Underdominance in viability homeostasis of the F1 hybrids suggested some incompatibility between populations. Homeostasis in thorax size was greater in females than in males and differed among parental populations. Maintenance of heritable differences and genetic variation for homeostasis in these traits suggested a role for cactus-specific differences in environmental uncertainty caused by variation in breeding site duration and abundance in nature.
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    Ultrastructure ofCyanoptyche gloeocystis f.dispersa (Glaucocystophyceae) (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 65-73 
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    ISSN: 1615-6110
    Keywords: Algae ; Glaucocystophyceae ; Cyanoptyche gloeocystis f.dispersa ; Ultrastructure ; endocytobiosis ; cyanelles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanoptyche gloeocystis f.dispersa (Geitler)Starmach is a palmelloid colonial alga that contains prokaryotic blue-green endocytobionts (cyanelles) instead of chloroplasts. The periphery of the host cell shows a peculiar lacunae system with underlying microtubules. Vegetative cells possess two rudimentary flagella. Zoospores are dorsiventrally shaped with two heterokont and heterodynamic flagella which originate from a subapical depression. This depression can also be seen in vegetative cells. Both flagella possess non-tubular mastigonemes. Main reserve product is starch lying freely in the cytoplasm. Cyanelles, enclosed singly in a host vesicle, are provided with a remnant cell wall. Thylakoids are arranged concentrically. The central part of each cyanelle harbours its DNA and one large polyhedral body, probably a carboxysome.Cyanoptyche gloeocystis f.dispersa shares all taxonomically essential characters with the monadoidCyanophora, the palmelloidGloeochaete, and the coccoidGlaucocystis. All of them are members of the cyanelle-bearing small algal classGlaucocystophyceae. Members of this class serve as model organisms for the evolution of chloroplasts from cyanophycean ancestors.
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    Cell multiplication and ultrastructure ofMicrasterias denticulata (Desmidiaceae) grown under salt stress (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 197-208 
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    ISSN: 1615-6110
    Keywords: Algae ; Chlorophyta ; Desmidiaceae ; Micrasterias ; Ultrastructure ; electron microscopy ; cell multiplication ; salt stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells ofMicrasterias denticulata Bréb. were kept in nutrient solution of high osmolality (salt stress) for four weeks. In a special cell multiplication test it was established that cell division is gradually inhibited at increasing salt concentrations and totally arrested at the highest concentration (26 mosm/kg). “Recovery studies” proved that even cells from the highest concentration range start dividing immediately after being placed in aqua bidest. thus indicating the full reversibility of the inhibiting effect. — Cells of the highest concentration range show marked ultrastructural changes. Besides an enormous accumulation of starch and oil bodies and a condensed appearance of the ground plasma, a reduction of mitochondria, ER and the Golgi-system is found. The most striking effect occurs on the vacuolar system which appears extremely reduced and condensed. The cell wall is thickened by the formation of an additional cell wall layer with a “spongy” electron microscopical appearance. Through the cell wall many droplets of a probably fat-like substance are excreted. — In summary, salt stress induces growth-inhibited “akinete” cells in the sense ofFritsch; these can be reactivated by decreasing the salt concentration. The salt-induced “akinete state” seems to be an ecological adaption to unfavourable conditions rather than a degeneration of the cells.
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    Mobile elements and transposition events in the cut locus of Drosophila melanogaster (1989)
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    Molecular genetics and genomics 219 (1989), S. 241-248 
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    ISSN: 1617-4623
    Keywords: Chromosomal walking ; Cut locus ; Drosophila ; Unstable mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have cloned from the Oregon R strain of Drosophila melanogaster a 240 kb segment of DNA that contains the cut (ct) locus, and characterized the region for the presence of repetitive elements. Within this region at least five copies of the suffix element were detected, as well as several putatively novel mobile elements. A number of mutations obtained from the unstable ct MR2 strain and its derivatives were mapped within the cut locus. Comparison between parental and daughter strains indicates that frequently two or more independent transposition events involving the cut locus occur simultaneously within a single germ cell, thus providing a molecular basis for the transposition explosion phenomenon.
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    Molecular cloning and transcript mapping of the dihydroorotate dehydrogenase dhod locus of Drosophila melanogaster (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 397-403 
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    ISSN: 1617-4623
    Keywords: Drosophila ; Pyrimidine biosynthesis ; Dihydroorotate dehydrogenase ; Molecular mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The dhod locus encodes dihydroorotate dehydrogenase, the fourth enzymatic step of de novo pyrimidine biosynthesis. This locus was cloned previously by a chromosome walk in cytogenetic region 85A. The location of dhod within 85A DNA has been determined by mapping two rearrangement mutations to a small DNA region. A nearly full-length cDNA clone of the dhod transcript was isolated and partially sequenced, to confirm its identity. The cDNA clone was also used to map the transcribed DNA. A 1.5 kb dhod RNA is described which is most abundant in embryos and displays minor length heterogeneity in pupae and adults. The developmental expression of this transcript is discussed relative to the expression of dihydroorotate dehydrogenase activity and other genes of the pyrimidine biosynthetic pathway.
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    Comparative ultrastructure of the zoospores of nine species ofNeochloris (Chlorophyta) (1989)
    Springer
    Plant systematics and evolution 168 (1989), S. 195-219 
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    ISSN: 1615-6110
    Keywords: Algae ; Chlorophyta ; Chlorophyceae ; Pleurastrophyceae ; Hydrodictyon ; Neochloris ; Pediastrum ; Sphaeroplea ; Ultrastructure ; flagellar apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nine species ofNeochloris can be divided into three groups on the basis of comparative ultrastructure of the flagellar apparatus, the cell wall and the pyrenoid of zoospores. In Group I,N. wimmeri andN. minuta, zoospores are thin-walled, pyrenoids are penetrated by stromal channels, and the basal bodies are in the clockwise absolute orientation and connected by the distal and two proximal fibers. In Group II,N. aquatica, N. vigenis, N. terrestris, N. pyenoidosa, andN. pseudostigmatica, zoospores are naked or covered by fuzzy material, pyrenoids are covered by a continuous starch sheath or invaginated by cytoplasmic channels, basal bodies are directly opposed, the distal fiber is differentiated into a ribbed structure at the central region, a striated microtubule-associated component (SMAC) is continuous between opposite two-membered rootlets and connected to the ribbed structure, proximal ends of basal bodies are covered by partial caps, each two-membered rootlet and a basal body are connected by a striated fiber to the X-membered rootlet associated with the opposite basal body, and the basal bodies, when oriented at wide angles, are joined at their proximal ends by core extensions. In Group III,N. pseudoalveolaris andN. cohaerens, zoospores are naked, pyrenoids are traversed by parallel thylakoids, basal bodies are in the counterclockwise absolute orientation and overlapped, and each X-membered rootlet is connected to the end of the opposite basal body by a terminal cap. It is suggested that the genusChlorococcopsis gen. nov. be erected for the Group I species. Group II, which includes the type species,N. aquatica, should be preserved asNeochloris. The group appears to be closely related to the coenobial generaPediastrum, Hydrodictyon, andSorastrum, and to have affinities with the coenocytic generaSphaeroplea andAtractomorpha as well. It is also suggested that the genusParietochloris gen. nov. be erected in thePleurastrophyceae for the species of Group III.
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    Genetic characterization of the mei-41 locus in Drosophila melanogaster (1989)
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    Molecular genetics and genomics 215 (1989), S. 190-199 
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    ISSN: 1617-4623
    Keywords: Mutagen sensitivity ; Recombination ; Gene structure ; Drosophila ; mei-41
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutagen-sensitive mutant mus(1)104 D1 of Drosophila melanogaster maps to a position on the X chromosome very close to the meiotic mutant mei-41 D5 . Both mutants have been characterized as mutagen-sensitive and defective in post-replication repair. In the present report we show by complementation studies that mus(1)104 and mus(1)103 are allelic with mei-41. In addition, two reported alleles of mus(1)104 lie between the mei-41 alleles A10 and D5. The size of the mei-41 locus is estimated to be about 0.1 centimorgans (cM). Because several alleles of mei-41 have been shown to reduce recombination and increase meiotic chromosome loss and nondisjunction, mus(1)104 D1 females were examined for defects in meiosis. Although there was no evidence for reduced recombination on the second chromosome in homozygous mus(1)104 D1 females, heterozygous mus(1)104 D1 /mei-41 〉D5 and mus(1)104 D1 /deficiency females showed reduced levels of recombination. However, there was no evidence of an increase in nondijunction in these females.
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    Cloning and analysis of fs(1) Ya, a maternal effect gene required for the initiation of Drosophila embryogenesis (1989)
    Springer
    Molecular genetics and genomics 215 (1989), S. 257-265 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Maternal effect ; Syngamy ; Embryonic development ; Molecular cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The maternal effect locus fs(1) Ya is required for the fusion of the apposed sperm and egg pronuclei (syngamy) following fertilization in Drosophila. It is tightly linked to another complementation group, fs(1) Yb, needed for both oogenesis and embryogenesis. We have isolated a set of overlapping cloned sequences in the 3B4-6 region of the X chromosome encompassing the fs(1) Ya-fs(1) Yb region. A single 2.4 kb maternal transcript is encoded with-in this region, and an 8.5 kb DNA fragment that contains this transcript complements both fs(1) Ya and fs(1) Yb mutations. Northern and in situ hybridization analyses show that the maternal transcript is only present in nurse cells and oocytes beginning in previtellogenic stages, and is evenly distributed in the cytoplasm of 0–2 h syncytial embryos. The transcript is not detected in later stages of embryonic development. This expression pattern correlates closely with the genetic and developmental characteristics expected of the fs(1) Ya gene product.
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    URL: http://dx.doi.org/10.1007/BF00339726
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    An abundant testis RNA species shows sequence similarity to Y chromosomal and other genomic sites in Drosophila hydei (1989)
    Springer
    Molecular genetics and genomics 215 (1989), S. 469-477 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Y chromosome ; Repetitive DNA ; Testis RNA ; Transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A cDNA clone bank was constructed from testis poly(A)+ RNA of Drosophila hydei and screened for clones which hybridize to Y chromosomal DNA sequences. The insert of clone cDhT14 hybridizes to a family of repeated DNA sequences with members distributed within the Y chromosome and elsewhere in the genome. This type of sequence has earlier been described as the Y-associated class of DNA. Southern blot analysis of DNA from different wild-type strains of D. hydei suggests that members of the T14 family of repeated DNA sequences are parts of a family of transposable elements. The genomic localization of the T14 family of repeated DNA sequences was revealed by in situ hybridization to metaphase and polytene chromosomes, and to transcripts of Y chromosomal lampbrush loops. Approximately 10–15 members (20%–30%) of the T14 sequence family reside in 8.3 kb PstI restriction fragments. A genomic clone of one of these DNA fragments, DhT14-8.3, hybridizes to transcripts on the Y chromosomal lampbrush loop “cones”, and in conventional in situ hybridization experments to region 12D/13A of the X chromosome and to region 112 of chromosome 5. The cDNA clone cDhT14 represents a part of an abundant testis RNA species of 5.0 kb. This RNA is also present in ovaries and in 0–3 h, 3–6 h and 6–12 h embryos, but less abundantly than in testes. Both the Y chromosomal site of the 8.3 kb PstI fragments and sites elsewhere in the genome are actively transcribed. At least one of the latter genomic sites is transcribed into the 5.0 kb RNA species. This poly(A)+ RNA is present in the cytoplasm of primary spermatocytes as shown by transcript in situ hybridization. The potential function of transcripts from Y chromosomal lampbrush loops is discussed.
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    URL: http://dx.doi.org/10.1007/BF00427045
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    Theamylase gene-enzyme system of fishes (1989)
    Springer
    Journal of comparative physiology 159 (1989), S. 237-242 
    Details
    ISSN: 1432-136X
    Keywords: Amylase ; Mosquitofish ; Rat ; Drosophila ; Structure ; Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Amylases from the mosquitofish (Gambusia affinis holbrooki, Pisces: Poeciliidae) and rat were purified and compared withDrosophila amylases in terms of structure and function. At the structural level, amino acid compositions of the three amylases were compared. At the functional level, amylase activities were compared on various substrates and in the presence of inhibitors. While the amylases from all three organisms had properties typical of alpha-amylases, both structural and functional differences were observed. Using resemblance coefficients of distance and similarity from numerical taxonomy, it was determined that the amylases from the rat andDrosophila were more similar to each other than either was to amylase from the mosquitofish, and that structural differences between the amylases did not reflect functional differences, i.e. there was no correlation between amylase structural and functional distances.
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    Ecological aspects of cactus triterpene glycosides I. Their effect on fitness components ofDrosophila mojavensis (1989)
    Springer
    Journal of chemical ecology 15 (1989), S. 663-676 
    Details
    ISSN: 1573-1561
    Keywords: Drosophila ; Diptera ; Drosophilidae ; triterpene glycosides ; cactus ; fitness components ; host-plant relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of pentacyclic triterpene glycosides extracted from agria and organ pipe cacti on three fitness parameters of the cactophilic fruit fly,Drosophila mojavensis were tested. Triterpene glycosides from organ pipe increased development time and reduced larval viability while those from agria produced smaller adults (reduced fecundity). In addition, the microbial communities in the organ pipe saponin media were less dense than those in the media to which agria saponins had been added. The role of cactus triterpene glycosides in the ecology of thisDrosophila species is discussed.
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    Effects of early adult experience on host selection in insects: Some experimental and theoretical results (1988)
    Springer
    Journal of insect behavior 1 (1988), S. 3-15 
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    ISSN: 1572-8889
    Keywords: host preference ; habitat selection ; experience ; learning ; Drosophila ; host races ; population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A field experiment with Drosophila melanogasterrevealed that when flies encounter a particular food type soon after emergence, the probability of their subsequently being attracted to such a resource is increased. In this experiment, the length of time flies experienced their postemergence environments was under the control of the flies themselves. The experiment thus realistically mimicked one form of experiential effect that may be important in nature. A theoretical model is developed which shows that enhanced adult preferences for the types of resources fed on as larvae can substantially increase the degree of host-based genetic subdivision within a polyphagous population.
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    Male mating activity and genetic aspects in imaginal diapause of Drosophila triauraria (1988)
    Springer
    Entomologia experimentalis et applicata 47 (1988), S. 81-88 
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    ISSN: 1570-7458
    Keywords: imaginal diapause ; male mating activity ; genetics ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les femelles de D. triauraria Bock & Wheeler (Dipt. Drosophilidae) sont connues pour présenter une diapause reproductrice aux photophases courtes. Les mâles eux aussi ont révélé une activité sexuelle réduite aux photophases courtes, c'est-à-dire qu'ils sont entrés comme les femelles en diapause reproductive. Les photophases critiques pour l'induction de la diapause des mâles et des femelles n'ont pas présenté de différences. Les diapause des mâles et des femelles s'achèvent même sous courtes photophases, mais la diapause mâle était quelque peu plus faible que la diapause femelle. La photophase critique et le taux de diapause ont varié en fonction de l'origine géographique dans l'espèce actuelle. Lors de croisements entre lignées diapausantes et non-diapausantes, la photophase critique et la durée de la diapause ont été héritées quantitativement. A partir de ces expériences et d'expériences précédentes de croisements (Kimura, 1983), quelques modèles de méchnisme d'induction de la diapause de cette espèce sont proposés.
    Notes: Abstract In Drosophila triauraria Bock & Wheeler (Diptera: Drosophilidae) of which females were known to enter reproductive diapause at short daylengths, males also showed reduced mating activity at short daylengths, i.e., males as well as females entered reproductive diapause. The critical daylength for diapause induction did not differ between females and males. Both male and female diapause ended even under short daylengths, but the male diapause was somewhat weaker than the female diapause. The critical daylength and the diapause rate varied geographically in this species. In the cross between diapausing and non-diapausing strains, the critical daylength and the diapause duration inherited in a quantitative manner. On the basis of the present and previous crossing experiments, some models are proposed on the mechanism of diapause induction of this species.
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    Alcohol dehydrogenase polymorphism inDrosophila: Enzyme kinetics of product inhibition (1988)
    Springer
    Journal of molecular evolution 28 (1988), S. 145-150 
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    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase ; Drosophila ; Enzyme kinetics ; Product inhibition ; Microevolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Because natural populations ofDrosophila melanogaster are polymorphic for different allozymes of alcohol dehydrogenase (ADH) and becauseD. melanogaster is more tolerant to the toxic effects of ethanol than its sibling speciesD. simulans, information regarding the sensitivities of the different forms of ADH to the products of ethanol degradation are of ecological importance. ADH-F, ADH-S, ADH-71k ofD. melanogaster and the ADH ofD. simulans were inhibited by NADH, but the inhibition was relieved by NAD+. The order of sensitivity of NADH was ADH-F〈ADH-71k, ADH-S〈ADH-simulans with ADH-F being about four times less sensitive than theD. melanogaster enzymes and 12 times less sensitive than theD. simulans enzyme. Acetaldehyde inhibited the ethanolto-acetaldehyde activity of the ADHs, but at low acetaldehyde concentrations ethanol and NAD+ reduced the inhibition. ADH-71k and ADH-F were more subject to the inhibitory action of acetaldehyde than ADH-S and ADH-simulans, with ADH-71k being seven times more sensitive than ADH-S. The pattern of product inhibition of ADH-71k suggests a rapid equilibrium random mechanism for ethanol oxidation. Thus, although the ADH variants only differ by a few amino acids, these differences exert a far larger impact on their intrinsic properties than previously thought. How differences in product inhibition may be of significance in the evolution of the ADHs is discussed.
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    Appendage morphogenesis in Drosophila: a developmental study of the rotund (rn) gene (1988)
    Springer
    Development genes and evolution 197 (1988), S. 19-26 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Morphogenesis ; Appendages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The phenotype of rotund (rn) null alleles is described, and compared to wild type. The mutants are expressed zygotically and cause position specific defects in certain imaginal discs (antenna, legs, wing, haltere and proboscis) and their corresponding adult derivatives. In the discs, specific folds are absent in rn mutants compared to wild type. Clonal analysis shows that the rn + gene is partially autonomous in its expression in cells destined to form certain distal parts of the adult appendages. The results are consistent with the idea that the rn + gene is required for normal morphogenesis of specific distal parts of the adult appendages.
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    The type and location of homeotic transformations in the tumorous-head mutant of Drosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 40-48 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Homeosis ; Tumorous-head ; Bithorax-complex mutant ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transformations of tumorous-head Drosophila melanogaster were examined in order to investigate whether head structures were replaced by specific abdominal structures. Heads selected for the presence of genital structures were analyzed in detail. Female abnormalities included any combination of vaginal teeth, vulvar papillae, sensilla trichodea, abdominal tergites 6 (T6), 7 (T7), 8 (T8) and anal plate. Anal plate was observed in the prefrons and rostral membrane, while all other genital structures were intimately associated with modified shingle cuticle. Male abnormalities included transformation of antennal structures to penis, clasper teeth, lateral plate, anal plate and eye to T6. The distribution of each type of homeotic structure was confined to general regions of the eye-antenna, with no precise dividing lines between them. However, the spatial sequence of homeotic structures in the eye-antenna was generally the same as the sequence of the same structures in the posterior abdomen.
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    Two groups of interrelated genes regulate early neurogenesis in Drosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 457-470 
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    ISSN: 1432-041X
    Keywords: Neurogenesis ; Neurogenic genes ; Achaetescute complex ; Daughterless ; Genetic interactions ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Drosophila melanogaster the neuroblasts separate from epidermoblasts to give rise to the neural primordium. This process is under the control of several genes. The group of the so-called neurogenic genes is required for epidermal development; other genes, comprising those of the achaete-scute complex and daughterless, are required for neural development. We have studied the relationships between both groups of genes in two different ways. We have analyzed the phenotype of double-mutant embryos and our results show that the neural hyperplasia caused by neurogenic mutations can be partially prevented if a mutation in one of the other genes is present in the same genome. Only the neural cells that do not require the function of a particular gene of the achaete-scute complex in the wild-type seem to develop to a neural fate in the double mutant embryos. At least some of the genetic interactions affect the transcriptional level, as shown by in situ hybridization, since the territories of transcription of the achaetescute genes are expanded in neurogenic mutants. All cells of the neurogenic region of the double mutants apparently initiate neural development. However, during later development some of these cells switch their fate either to epidermogenesis or to cell death and this leads to the final phenotype of the double mutants. We discuss these results with respect to the events of early neurogenesis.
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    URL: http://dx.doi.org/10.1007/BF00385679
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    Induced neuroma formation and target muscle perturbation in the giant fiber pathway of the Drosophila temperature-sensitive mutant shibire (1988)
    Springer
    Development genes and evolution 197 (1988), S. 383-393 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; shibire ; Neuronal development ; Muscle ; Giant fiber pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The temperature-sensitive mutation shibire (shi) in Drosophila melanogaster is thought to disrupt membrane recycling processes, including endocytotic vesicle pinch-off. This mutation can perturb the development of nerves and muscles of the adult escape response. After exposure to a heat pulse (6 h at 30° C) at 20 h of pupal development, adults have abnormal flight muscles. Wing depressor muscles (DLM) are reduced in number from the normal six to one or two fibers, and are composed of enlarged fibers that appear to represent fiber fusion; large spaces devoid of muscle fibers suggested fiber deletion. The normal five motor axons are present in the peripheral nerve PDMN near the ganglion. However, while some motor axons pass dorsally to the extant fibers, other motor axons lacking end targets pass into an abnormal posterior branch and terminate in a neuroma, i.e., a tangle of axons and glia without muscle target tissue. Hemisynapses are common in axons of the proximal PDMN and within the neuroma, but they are rarely seen in control (no heat pulse) shi or wild-type flies. All surviving muscle fibers are innervated; no muscle tissue exists without innervation. Fibrillar fine structure and neuromuscular synapses appear normal. Fused fibers have dual innervation, suggesting correct and specific matching of target tissue and motor axons. Motor axons lacking target fibers do not innervate erroneous targets but instead terminate in the neuroma. These results suggest developmental constraints and rules, which may contribute to the orderly, stereotyped development in the normal flight system. The nature of the anomalies inducible in the flight motor system in shi flies implies that membrane recycling events at about 20 h of pupal development are critical to the formation of the normal adult nerve-muscle pattern for DLM flight muscles.
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    URL: http://dx.doi.org/10.1007/BF00398989
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    Reversible commitment of neural and epidermal progenitor cells during embryogenesis of Drosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 413-418 
    Details
    ISSN: 1432-041X
    Keywords: Cell interactions ; Cell commitment ; Neurogenesis ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell-cell interactions are involved in mediating developmental fate. An example is the decision of the neuroectodermal cells of Drosophila to develop as neural or epidermal progenitors, where cellular interactions participate in the process of acquisition of either cell fate. The results of heterochronic cell transplantations we describe here suggest that both neuroblasts and epidermoblasts are not irreversibly committed to a particular developmental fate. Rather, they retain the ability to interact with neighbouring cells and, under our experimental conditions, are capable of switching their fate during a relatively long period of time, i.e. until the end of embryonic stage 11.
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    Genetic interaction between homoeotic Sex combs reduced and Regulator of bithorax (or trithorax) genes of Drosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 435-440 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Homoeotic genes ; Segment differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Regulator of bithorax (Rg-bx)−, or trithorax (trx)− lethal larvae occasionally show a homoeotic transformation of the dorsal prothorax to mesothoracic structures. This transformation suggests a reduced activity of the Sex combs reduced (Scr) gene on the basis of gene dosage studies, as well as enhanced expression of the phenotypes of the weak Scr − alleles in Rg-bx − larvae. Morphological observations of adult flies doubly heterozygous for Rg-bx and Scr mutations also suggest the enhancement of an aspect of Scr adult phenotypes. I conclude that the Rg-bx + gene function is required for the optimal expression of the Scr gene in larval and imaginai cells.
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    Expression of a reporter gene resembles that of its neighbour: an insertion in the hairy gene of Drosophila (1988)
    Springer
    Development genes and evolution 197 (1988), S. 507-512 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Reporter gene ; hairy ; Segmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Random insertions of a promotor fused to a reporter gene, such as Lac-Z, reveal regulatory sequences that confer temporal and spatial patterns of gene expression in eukaryotes. These patterns may reflect the activity of a neighbouring gene and thus lead to the isolation of new genes essential for normal development. Here, we demonstrate that this hypothesis is true for an insertion into the well characterized segmentation gene, hairy, in Drosophila. The insertion is homozygous lethal and fails to complement other hairy alleles, giving the phenotype described for hairy mutations. The insertion is located at 66D on the polytene chromosome map, is within 300–600 bp 5′ to the first hairy exon, and is orientated in the same sense (5′-3′) as the hairy transcription unit. Expression of β-galactosidase (β-gal), deriving from the insertion, follows closely the spatio-temporal patterns of expression of hairy gene product during embryogenesis. In addition, other sites of β-galactosidase expression are shown in the third larval instar stage and in the adult ovary. The results show that some insertions, giving restricted patterns of reporter gene expression, will reflect the temporo-spatial activity of a nearby gene.
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    Abnormal ovarian morphogenesis in Drosophila melanogaster after injection of embryos with conditioned media from the Daudi cell line (1988)
    Springer
    Development genes and evolution 197 (1988), S. 370-374 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Injection of embryo ; Daudi conditioned medium ; Rudimentary ovaries ; Mean number of ovarioles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila melanogaster embryos were injected before the blastoderm stage with conditioned media from several male Burkitt's lymphoma human cell lines and the Daudi cell line. Such injections do not have any effect on the male genital apparatus or on the female tract. The Daudi conditioned medium modifies the ovarian morphogenesis of the flies and the rudimentary ovaries obtained look like nymphal gonads. Moreover, they have a drastically reduced number of germ cells. The ovaries that looked functional contain numerous necrotic germ cells and the mean number of ovarioles per fly is significantly smaller than that of the controls. The abnormalities observed resemble the results of experimental and genetic lack of germ cells. They disappear at very high dilution (1×10−6).
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    Electrically mediated protein movement inDrosophila follicles (1988)
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    Development genes and evolution 197 (1988), S. 231-238 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Electrical polarity ; Ovarian follicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Distribution of rhodamine-conjugated lysozyme injected into the sixteen-cell syncytium comprising the germ-line portion of theDrosophila follicle is shown to be affected by charge. Positive molecules are able to migrate through intercellular bridges from the oocyte to the nurse cells, but are unable to migrate detectably from nurse cells to the oocyte. Their negatively charged counterparts can move from the nurse cells to the oocyte, but are unable to traverse the intercellular bridges in the counter direction. This charge-dependent movement of molecules is accompanied by an electrical potential difference, focused across the nurse cell-oocyte bridges, which makes the nurse cells negatively charged to the oocyte. The addition of insect hemolymph to the physiological salt solution in which the experiments were performed resulted in only a small increase in the transmembrane resistance, but enhanced the potential difference between oocyte and nurse cells from 0.2±0.3 (SE) mV (nurse cells negative) to 2.3±0.45 (SE) mV (nurse cells negative).
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    Maternal and zygotic requirement for thepolyhomeotic complex genetic locus inDrosophila (1988)
    Springer
    Development genes and evolution 197 (1988), S. 239-246 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeosis ; Epidermal development ; Embryology ; Clonal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The complex genetic locuspolyhomeotic (ph) is a member of thePolycomb (Pc)-group of genes and as such is required for the normal expression of ANT-C and BX-C genes. It also has probably other functions since amorphicph alleles display a cell death phenotype in the ventral epidermis of 12-h-old embryos. Here it is shown that lethal alleles ofph (amorph and strong hypomorph) show transformation of most of their segments towards AB8. Theph + product is required autonomously in imaginal cells. The total lack ofph + function prevents viability of the cuticular derivatives of these cells.ph has a strong maternal effect on segmental identity and epidermal development that can not be rescued by one paternally supplied dose ofph + in the zygote. These phenotypes differ substantially from those of previously describedPc-group genes. AmongPc-group genes,ph seems to be the only one that is strongly required both maternally and zygotically for normal embryonic development.
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    The reinforcement-extinction process of selector gene activity: a positive feed-back loop and cell-cell interactions in Ultrabithorax patterning (1988)
    Springer
    Development genes and evolution 197 (1988), S. 424-434 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Ultrabithorax ; Development ; Regulation ; Protein distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Most viable alleles of homeotic genes cause partial transformations within given lineages in a topographically specific fashion. We study this phenomenon as a way to understand the normal mechanisms involved in the spatial regulation of homeotic gene expression. To this end we have investigated the distribution of Ultrabithorax (Ubx) proteins in imaginai discs mutant for hypomorphic and neomorphic alleles of Ubx and alleles of trans-acting genes. We find that the morphological discontinuities observed in the adult transformations are caused by corresponding new patterns of the Ubx proteins in the imaginai anlagen. These novel patterns of Ubx proteins are understood as a consequence of a process of reinforcement-extinction of Ubx expression. The evidence suggesting that this process results from a positive feed-back loop and cell-cell interactions is discussed.
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    Mutational dissection of gene expression in the abdominal region of the bithorax complex of Drosophila in imaginal tissue (1988)
    Springer
    Development genes and evolution 197 (1988), S. 131-140 
    Details
    ISSN: 1432-041X
    Keywords: Bithorax complex ; Drosophila ; Abdominal-B mutations ; Genetic mosaics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The phenotypic effects in imaginal hypodermal tissue of a number of Abdominal-B mutations of the bithorax complex are described. Evidence is given from complementation analysis that the phenotypic heterogeneity in both the spatial limits and the nature of the homeotic transformations produced is not an arbitrary classification of allelic differences that we find. We have used genetic mosaic analysis to support the interpretation that the Abdominal-B genetic unit can exist in a number of alternative functional states of expression during development and that individual Abdominal-B mutations may abolish some states whilst leaving others unaffected.
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    URL: http://dx.doi.org/10.1007/BF00427916
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    Genetic analysis of viable and lethalfused mutants ofDrosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 221-230 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Segment polarity gene ; Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fused is a segmentation gene belonging to the segment-polarity class. Mutations at thefused locus are known to display pleiotropic effects, causing zygotically determined anomalies of ovaries and of some adult cuticular structures, and maternally determined embryonic segmentation defects. In order to determine the amorphic phenotype offused and to study the genetical basis of its pleiotropy, newfused alleles (18 viable and 11 lethal) were isolated. The phenotype of these mutants and of others already known are described, taking into account zygotic and maternal effects. The main results provided by this analysis are as follows. Firstly, allfused alleles show the whole complex fused phenotype, and a good correlation is observed between the strength of the wing and segmentation defects, suggesting that a single function is involved in both processes. Secondly, all embryonic and larval lethals carry deficiencies which allow us to localizefused between the 17C4 and 17D2 bands of the X-chromosome. Thirdly, the 24 viable and 2 pupal lethals examined behave as point mutants, as shown cytologically or by Southern blot analysis. However, only one of them, the pupal lethalfu mH63 was proven to carry a nullfused allele, since it displays in germ-line clones a strong maternal phenotype and a very low zygotic rescue, similar to those of the small deficiencyDf(1)fu z4. The phenotype of the amorphic mutant indicates that zygotic ezpression offused is required for normal metamorphosis, while maternal expression is necessary for a normal segmentation pattern, since a complete loss offused expression during oogenesis cannot be compensated zygotically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439429
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    Developmental analysis of fs(1)gastrulation defective, a dorsal-group gene of Drosophila melanogaster (1988)
    Springer
    Development genes and evolution 197 (1988), S. 75-91 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Maternal effect mutation ; Pattern formation ; Gastrulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The gastrulation defective (gd) locus is a maternally expressed gene in Drosophila required for normal differentiation of structures along the embryonic dorso-ventral axis. Cuticular defects of the offspring from females with different combinations of gd alleles comprised a phenotypic continuum. Complementation among several alleles produced normal offspring while progressively more severe mutations produced a graded loss of structures from ventral, and then lateral, blastoderm cells. The most severely affected embryos consisted entirely of structures derived from dorsal blastoderm cells. Histological examination of staged siblings from selected allelic combinations showed that internal tissues were similarly affected. The tissues observed in amorphic embryos support new, more dorsal, assignments of fate map positions for blastoderm precursors of the cephalopharyngeal apparatus, hindgut and ventral nerve cord. The loss of ventral and lateral structures did not occur through cell death and appeared to involve a change in blastoderm cell fate. A direct effect of the mutations on blastoderm cell determination, however, was insufficient to explain the development of the dorsalized embryos. Intermediate phenotypes suggested that cell interactions or movements associated with morphogenesis are required for the determination of some cell fates in the dorsoventral axis. Thus, the developmental fate of all blastoderm cells may not be fixed at the time of blastoderm formation.
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    URL: http://dx.doi.org/10.1007/BF00375930
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    Dominant maternal interactions with Drosophila segmentation genes (1988)
    Springer
    Development genes and evolution 197 (1988), S. 115-123 
    Details
    ISSN: 1432-041X
    Keywords: X-Chromosome Loci ; Dominant maternal effect ; Segmentation genes ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A systematic search for X chromosome loci showing a dominant maternal interaction with the segmentation genes Krüppel, hunchback, knirps and hairy was performed using deficiencies spanning 65% of the X chromosome. No interaction with the knirps gene was observed, but five regions of the X chromosome showed a maternal dominant interaction with the Krüppel gene. Two of these regions also show a maternal dominant interaction with either hunchback (region 10A7–10A8) or hairy (region 10E1–10F3). In all of these interactions dead embryos were observed which showed the same defects as embryos homozygous for the segmentation gene tested. These results suggest that a complex repartition of maternal products necessary for subsequent segmentation may occur in the Drosophila egg.
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    URL: http://dx.doi.org/10.1007/BF00375934
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    The vectoring of cactophilic yeasts by Drosophila (1988)
    Springer
    Oecologia 75 (1988), S. 400-404 
    Details
    ISSN: 1432-1939
    Keywords: Vectoring ; Drosophila ; Cactophilic yeasts ; Dispersal ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At two locations in the Sonoran Desert, yeasts were sampled from species of Drosophila, the flies' cactus hosts, and other neighboring sources of cactophilic yeasts to determine the relation between the yeasts vectored by the fly and the yeasts found in their breeding sites. D. mojavensis, D. nigrospiracula, and D. mettleri vectored yeast assemblages significantly more similar to the yeast species found on the rot from which the flies were collected than to the yeasts found on other rots from the flies host cactus or other rotting cactus at the same site. Rots with Drosophila had fewer yeast species than those without flies, suggesting that flies were associated with younger rots. Rots with flies and the Drosophila also had more yeast species with the capability to produce ethyl acetate than rots without flies. The results support the contention that cactophilic Drosophila feed on a subset of the yeasts available in an area, and may act to maintain differences among the yeast communities found on different species of cactus.
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    URL: http://dx.doi.org/10.1007/BF00376943
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    Interaction between a picornavirus and a wild population ofDrosophila melanogaster (1988)
    Springer
    Oecologia 75 (1988), S. 516-520 
    Details
    ISSN: 1432-1939
    Keywords: Drosophila ; Picornavirus ; Fertility ; Embryonic and larvo-pupal death rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila C virus (DCV) has a considerable impact on ovarian morphogenesis inDrosophila melanogaster host populations. This virus also affects the developmental time and the fresh weight of infected females. In order to investigate the hypothesis that DCV may play a role in the dynamics ofDrosophila populations, the fertility and embryonic and larvo-pupal death rates of a host population and that of five DCV-free populations were determined. A comparison of two populations, one of them DCV-free, the other infected, suggested that the fertility of the DCV-infected flies was higher than that of uninfected flies, despite a greater larvo-pupal death rate. Fertility of the infected flies was greater among the infected population than for the DCV-free populations. The DCV-free populations originated from five different localities. The virus clearly does have an impact on the biotic potential of its host population. This paper reports for the first time a positive interaction between a viral population and a host population as it increases certain parameters of host population dynamics.
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    URL: http://dx.doi.org/10.1007/BF00776414
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  • 80
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    Pre-fertilization degeneration of both synergids in Brassica campestris ovules (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 208-216 
    Details
    ISSN: 1432-2145
    Keywords: Megagametophyte ; Synergids ; Brassica campestris ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Brassica campestris, both synergids of the ovule degenerate before the arrival of the pollen tube. Synergid degeneration does not depend on pollination. At the non-degenerated stage, the synergids are completely filled with a complexly organized cytoplasm containing numerous mitochondria with many cristae, a large number of dictyosomes with many associated vesicles, and a very extensive rough endoplasmic reticulum. The degenerative changes that occur in the cytoplasm of the synergids are characterized by a loss of visibility of the membranes of the endoplasmic reticulum and the simultaneous formation of dense deposits on the surrounding membranes of the mitochondria. Locally, the plasma membranes of the synergids disappear, and some ground plasma of the synergids penetrates into the space between the plasma membranes of the egg cell and the central cell.
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    URL: http://dx.doi.org/10.1007/BF00189154
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    Ultrastructural and cytochemical examination of the nuclear crystalloid inclusions of Olea europaea L. mesophyll cells (1988)
    Springer
    Trees 2 (1988), S. 261-266 
    Details
    ISSN: 1432-2285
    Keywords: Nuclear crystalloid inclusions ; Olea europaea ; Cytochemistry ; Ultrastructure ; Glycoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The nuclei of mesophyll cells of olive trees contain numerous sizeable crystalloid inclusions. Cytochemical examination using epoxy resin-embedded, semithin-sectioned tissue indicated the presence of proteins and oligoor polysaccharides in these inclusions. Their electron microscopical analysis revealed a crystalline substructure consisting of intersected subunits of high order. The spacing of the lattice fibrils and the angles of intersection were determined and used to establish a model of the unit cell of crystallization. It is suggested that the nuclear crystalloids of olive trees consist of glycoprotein molecules. They differ from the intranuclear crystalloids observed in other species predominantly in the high density of their subunit arrangement.
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    URL: http://dx.doi.org/10.1007/BF00202381
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    Cytoplasmic and mitochondrial arginine kinases inDrosophila: Evidence for a single gene (1988)
    Springer
    Biochemical genetics 26 (1988), S. 131-141 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; arginine kinase ; mitochondria ; isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mitochondrial and cytoplasmic isozymes of arginine kinase have been identified inDrosophila melanogaster. On the basis of their immunological similarity, parallel dosage responses, and cosegregation of electrophoretic mobility differences, it is concluded that both isozymes are the product of a single gene. The consequences of this in relation to the regulation and evolution of this unusual gene-enzyme system are discussed. It is inferred that the origin of the phosphagen shuttle must predate the divergence of invertebrates and vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00555494
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    Genetic characterization of dipeptidase activity modifiers inDrosophila melanogaster from natural populations (1988)
    Springer
    Biochemical genetics 26 (1988), S. 783-803 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; dipeptidase activities ; genetic variation ; activity modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An examination ofDrosophila melanogaster from natural populations revealed genetic variation for dipeptidase-A (DIP-A) and dipeptidase-B (DIP-B) activities within sets of lines that differed from one another only in the second or the third chromosome. Analyses of diallel crosses indicate that both activities are inherited additively, and coordinate control of expression is suggested by the significant positive correlation between the two activities. Electrophoresis and thermal denaturation studies failed to detect structural differences among lines with different levels of DIP-A activity. No characteristic level of activity could be associated with any DIP-A allozyme. Mapping experiments revealed the presence of activity modifiers that are in tight linkage with the structural gene, as well as those that manifest their effects from a distance. The maximum genetic distance between a high-activity effect on DIP-A and the structural gene was determined to be 0.029 map unit. These results are in accordance with the prevalence of activity modifiers for various enzymes inDrosophila melanogaster.
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    URL: http://dx.doi.org/10.1007/BF02395523
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    Genetic determinants of glutamine synthetase inDrosophila melanogaster: A gene for glutamine synthetase I resides in the 21B3-6 region (1988)
    Springer
    Biochemical genetics 26 (1988), S. 571-584 
    Details
    ISSN: 1573-4927
    Keywords: glutamine synthetase I ; genetic mapping ; allozymes ; null alleles ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recombinational and deletion mapping of electrophoretic variants of the glutamine synthetase I isozyme (GSI) inDrosophila melanogaster locates the gene in the 21B region on the second chromosome. We have conducted a genetic analysis of the region extending cytologically from 21A to 21B4-6. Recessive lethal mutations were generated by ethyl methanesulfonate (EMS) and ethyl nitrosourea (ENU) mutagenesis and by hybrid dysgenesis (HD). These lethals fall into seven functional groups, which were partially ordered by complementation with cytologically defined deficiencies of this region generated by hybrid dysgenesis. Two of the EMS- and two of the ENU-induced lethals fulfill biochemical criteria expected for null alleles of the GSI gene.
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  • 85
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    Genetic characterization of dipeptidase activity modifiers inDrosophila melanogaster from natural populations (1988)
    Springer
    Biochemical genetics 26 (1988), S. 783-803 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; dipeptidase activities ; genetic variation ; activity modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An examination ofDrosophila melanogaster from natural populations revealed genetic variation for dipeptidase-A (DIP-A) and dipeptidase-B (DIP-B) activities within sets of lines that differed from one another only in the second or the third chromosome. Analyses of diallel crosses indicate that both activities are inherited additively, and coordinate control of expression is suggested by the significant positive correlation between the two activities. Electrophoresis and thermal denaturation studies failed to detect structural differences among lines with different levels of DIP-A activity. No characteristic level of activity could be associated with any DIP-A allozyme. Mapping experiments revealed the presence of activity modifiers that are in tight linkage with the structural gene, as well as those that manifest their effects from a distance. The maximum genetic distance between a high-activity effect on DIP-A and the structural gene was determined to be 0.029 map unit. These results are in accordance with the prevalence of activity modifiers for various enzymes inDrosophila melanogaster.
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    Glue proteins inDrosophila nasuta (1988)
    Springer
    Biochemical genetics 26 (1988), S. 527-541 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; glue proteins ; glycosylation ; Chromosomal linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larval glue protein fractions ofDrosophila nasuta nasuta were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Seven major and at least four minor glue protein fractions were recognized. Six of the major fractions are glycosylated. They migrate as three prominent doublets (〉100, 43, and 30/28 kd). The synthesis of traceable amounts of these major fractions begins already during the second as well as during the early stages of the third larval instar. The 43-kd and the 30/28-kd fractions are coded by X-chromosomal genes. They are probably clustered within the huge puff of division 10, which is the most prominent X-chromosomal puff in the polytene chromosomes of the third larval instar. Complex posttranslational modification of all but one major glue protein fraction (14 kd) leads to the formation of about 15 different protein fractions in the final glue product. The amount of glue protein produced byD. n. nasuta larvae (in relation to the total saliva proteins) is nearly twice the amount produced byD. melanogaster larvae (ca. 55 and 32%, respectively).
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    Genetic determinants of glutamine synthetase inDrosophila melanogaster: A gene for glutamine synthetase I resides in the 21B3-6 region (1988)
    Springer
    Biochemical genetics 26 (1988), S. 571-584 
    Details
    ISSN: 1573-4927
    Keywords: glutamine synthetase I ; genetic mapping ; allozymes ; null alleles ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recombinational and deletion mapping of electrophoretic variants of the glutamine synthetase I isozyme (GSI) inDrosophila melanogaster locates the gene in the 21B region on the second chromosome. We have conducted a genetic analysis of the region extending cytologically from 21A to 21B4-6. Recessive lethal mutations were generated by ethyl methanesulfonate (EMS) and ethyl nitrosourea (ENU) mutagenesis and by hybrid dysgenesis (HD). These lethals fall into seven functional groups, which were partially ordered by complementation with cytologically defined deficiencies of this region generated by hybrid dysgenesis. Two of the EMS- and two of the ENU-induced lethals fulfill biochemical criteria expected for null alleles of the GSI gene.
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    URL: http://dx.doi.org/10.1007/BF00553780
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    Purification and properties of theDrosophila zen protein (1988)
    Springer
    Molecular and cellular biochemistry 79 (1988), S. 181-189 
    Details
    ISSN: 1573-4919
    Keywords: zerknullt gene ; homeobox protein ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The zen protein is encoded by the zerknullt gene required for normal early development inDrosophila. Like many regulatory proteins of this type, zen contains a 60 amino acid homeobox sequence. We have purified the zen protein and studied its solution behavior and its interaction with DNA. The zen protein exists as a monomer in solution with a molecular weight of about 40000. It binds specifically to a site about 900 bases upstream from thezen gene. Within this binding site DNase protection experiments indicate that binding is confined to two regions approximately 11 and 14 bases in length that are separated by about 30 base pairs. The protein concentration dependence of the binding curve suggests that protein binding is non cooperative.
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    URL: http://dx.doi.org/10.1007/BF02424561
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  • 89
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    Glue proteins inDrosophila nasuta (1988)
    Springer
    Biochemical genetics 26 (1988), S. 527-541 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; glue proteins ; glycosylation ; Chromosomal linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larval glue protein fractions ofDrosophila nasuta nasuta were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Seven major and at least four minor glue protein fractions were recognized. Six of the major fractions are glycosylated. They migrate as three prominent doublets (〉100, 43, and 30/28 kd). The synthesis of traceable amounts of these major fractions begins already during the second as well as during the early stages of the third larval instar. The 43-kd and the 30/28-kd fractions are coded by X-chromosomal genes. They are probably clustered within the huge puff of division 10, which is the most prominent X-chromosomal puff in the polytene chromosomes of the third larval instar. Complex posttranslational modification of all but one major glue protein fraction (14 kd) leads to the formation of about 15 different protein fractions in the final glue product. The amount of glue protein produced byD. n. nasuta larvae (in relation to the total saliva proteins) is nearly twice the amount produced byD. melanogaster larvae (ca. 55 and 32%, respectively).
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    Behavior, stress, and variability (1988)
    Springer
    Behavior genetics 18 (1988), S. 293-308 
    Details
    ISSN: 1573-3297
    Keywords: stress ; domestication ; extreme environments ; human evolution ; mice ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Genetic variability of behavioral traits under optimal and stressful environments is considered with examples fromDrosophila, rodents, and our own species. In agreement with direct fitness and life history traits, behavioral traits show a maximization of preexisting andde novo variation under stress. In order to understand evolutionary change,it appears necessary to emphasize those traits showing interactions with habitats under conditions of environmental stress; this can be shown at the behavioral level especially for domestication and adaptation to novel habitats.
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    URL: http://dx.doi.org/10.1007/BF01260931
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    Genetic variability of sexual behavior in a natural population ofDrosophila melanogaster (1988)
    Springer
    Behavior genetics 18 (1988), S. 389-403 
    Details
    ISSN: 1573-3297
    Keywords: sexual selection ; sexual behavior ; assortative mating ; polymorphism ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Although many experiments on laboratory stocks ofDrosophila have suggested that mate choice is a major feature of sexual selection in this organism, few attempts have been made to measure its extent in wild populations. In this study, a crossing design was used to obtain a set of 13 genetically identical independent lines representative of genotypes from an African population ofDrosophila melanogaster. They were tested for variation in sexual behavior using dyadic tests. Significant variation in orientation and vibration latencies was found for males, and in mating speed and copulation duration for both sexes. No evidence of assortative mating, either positive or negative, was found. The absence of a correlation in mating speed between males and females sharing the same genotype leads us to doubt the applicability of the notion of “male eagerness” and “female reluctancy” inDrosophila and the importance of “vigor” as a factor in mating speed. The absence of mate choice in natural populations ofDrosophila seems to us the most likely hypothesis on the basis of both theory and empirical evidence.
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    URL: http://dx.doi.org/10.1007/BF01260939
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    Spectral analysis ofDrosophila courtship songs:D. melanogaster, D. simulans, and their interspecific hybrid (1988)
    Springer
    Behavior genetics 18 (1988), S. 675-703 
    Details
    ISSN: 1573-3297
    Keywords: reproductive behavior ; pulse song ; sine song ; acoustic spectrum ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Digital signal processing methods have revealed spectral components inDrosophila melanogaster's andD. simulans' male courtship songs that had gone undetected in previous studies. We found that a bout of courtship hum (“sine song”) inD. simulans typically consists of a narrowband fundamental frequency, accompanied by second and third harmonics that can comprise a major fraction of the power in the signal. The pulse song spectra consisted of single broad-band peaks of highly variable frequencies, which, nevertheless, are characteristically different in these two species. Genetic elements of the newly discovered song components were examined by analysis of theD. melanogaster/D. simulans hybrid. Such males were found to be intermediate in production of sine song harmonics as well as in other parameters of courtship song, except for sine song and intrapulse frequency bandwidths, for which there may be dominant factors inD. simulans.
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    URL: http://dx.doi.org/10.1007/BF01066850
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    Components of fitness in a compound chromosome strain of Drosophila melanogaster (1988)
    Springer
    Theoretical and applied genetics 75 (1988), S. 468-473 
    Details
    ISSN: 1432-2242
    Keywords: Compound chromosomes ; Fitness ; Drosophila ; Assortative mating ; Pest control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relative net fitness of a compound chromosome strain of Drosophila melanogaster was about 0.05, compared with the chromosomally normal strain from which it was derived. Based on meiotic considerations alone, the expected relative fitness was about 0.25. There were no significant differences in fertility between the compound and normal strains; the compound strain produced about 28% as many offspring as the normal strain and developed faster than the normal strain in two replicates, and slower in one replicate. The low relative fitness of the compound strain was apparently due to assortative mating, in which normal females discriminated strongly against compound males. Implications for pest control projects are dicussed.
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    URL: http://dx.doi.org/10.1007/BF00276751
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    Lipid detection by malachite green-aldehyde in the dental basement membrane in the rat incisor (1988)
    Springer
    Cell & tissue research 253 (1988), S. 685-687 
    Details
    ISSN: 1432-0878
    Keywords: Basement membrane ; Lipids ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Developing rat incisors were treated with malachite green-aldehyde fixative solution (MGA), which retains and stains lipids. We observed positive staining occurring as dots in the basement membrane. Most of these dots (2–3.5 nm in diameter) were grouped in the lamina densa but some were also present in the lamina lucida and the lamina fibroreticularis. These data provide evidence for the existence of lipids in the dental basement membrane and suggest that they are distributed together with the various groups of proteins so far detected.
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    URL: http://dx.doi.org/10.1007/BF00219762
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    Catecholaminergic nerves in the embryonic chick ovary: co-localization with β2-adrenoceptor-bearing steroidogenic cells (1988)
    Springer
    Cell & tissue research 254 (1988), S. 1-9 
    Details
    ISSN: 1432-0878
    Keywords: Adrenergic nerves ; Steroidogenic cells ; Embryonic ovary ; β 2Adrenoceptors ; Cytochemistry ; Ultrastructure ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study investigates the innervation of the embryonic chick ovary with regard to (i) development and compartmentalization of catecholaminergic nerves, and (ii) presence of adrenoceptors on steroidogenic target cells of catecholaminergic nerve terminals. Catecholaminergic nerve fibers visualized by glyoxylic acid-induced histofluorescence first appeared at embryonic day (E) 13. From E15 through E21 the density of fluorescent aminergic nerves increased markedly in parallel with the concentration of catecholamines and numbers of nerve bundles and single axons seen at the electron-microscopic level. Catecholaminergic nerves were confined to the ovarian medulla and closely associated with interstitial cells. Nerve terminals approached interstitial cells up to a distance of 20 nm and, in their majority, exhibited uptake of the false adrenergic transmitter 5-hydroxydopamine. Although adrenaline amounted to 14% of the total catecholamine content at E21, adrenaline immunoreactivity was only detected in adrenal chromaffin cells, but not in nerve fibers or cell bodies within the ovary. Interstitial cells structurally matured between E15 and E21 as documented by an increase of smooth endoplasmic reticulum and tubular mitochondria. Monoclonal antibodies mAB 120 and BRK 2 raised against avian β 1 and mammalian β 2-adrenergic receptors revealed the presence of β 2-adrenoceptor-like immunoreactivity on the surface of interstitial cells, but not on any other cell type. The results are consistent with the notion of a dense adrenergic innervation of the embryonic chick ovarian medulla and its steroidogenic interstitial cells, and suggest the chick ovary as an excellent model for elucidating the functional role of a neural input to steroidogenic cells during development.
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    URL: http://dx.doi.org/10.1007/BF00220010
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    The pattern of organization of intermediate filaments and their asymmetrical association with dense bodies in smooth muscle of an ascidian Halocynthia roretzi (1988)
    Springer
    Cell & tissue research 252 (1988), S. 23-32 
    Details
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Intermediate filaments ; Dual network ; Ultrastructure ; Ascidian ; Halocynthia roretzi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An extensive network of intermediate filaments that interconnected cytoplasmic dense bodies and connected the dense bodies to the cell surface was revealed in double-fixed, tannic acid-stained preparations of ascidian smooth muscle. The filament network ran through spaces in the continuous network of myofibrils, connecting them longitudinally, obliquely and transversely to form an intimately associated, dual network. In their transverse passage, the intermediate filaments ran across myofibrils along I-zones exclusively, interconnecting successive dense bodies. The pattern of attachment of intermediate filaments to dense bodies was predominantly “one-sided.” The filaments, which themselves were not incorporated into the contractile apparatus, remained folded or unfolded between myofibrils and between sarcomere-like structures in synchrony with the contraction-relaxation cycles. These results suggest that the intermediate filaments mechanically maintain the organization and arrangement of myofibrils via an intimate association with the myofibrils in the regions of the dense bodies, in such a way that the filaments do not impede muscle function. Based on these observations, a new model for the network of intermediate filaments in smooth muscle cells is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213822
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  • 97
    Electronic Resource
    Electronic Resource
    Ultrastructure of the tentacles of the apodous holothurian Leptosynapta spp (Holothurioidea: Echinodermata) with special reference to the epidermis and surface coats (1988)
    Springer
    Cell & tissue research 251 (1988), S. 387-397 
    Details
    ISSN: 1432-0878
    Keywords: Tentacles ; Ultrastructure ; Adhesion ; Leptosynapta spp (Holotheorie) ; Echinodermata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tentacles of the apodous holothurian Genus Leptosynapta have been studied by use of transmission and scanning electron microscopy. The gross anatomy, water vascular system, fibre systems and ectoneural nerve ring are described. A fuzzy coat of attenuated filaments covers the surface of the tentacle, broken only by secretory ducts. A cuticle underlies the fuzzy coat. Bacteria are common in the subcuticular space. Fixation without osmium gives poor preservation of the surface coats. The epidermis consists of a single layer of columnar cells consisting of Type-1, Type-2, support, goblet and uniciliated cells. Type-1 cells secrete electron-dense material and appear to be homologous to adhesive cells of the tentacles of other holothurians. The support cells contain large, granular vesicles not found in other holothurians. Goblet cells contain flocculent mucus and have an apical cilium. Goblet cells are not found in other holothurian tentacles and may function to lubricate and wrap adhering particles to aid their ingestion. The uniciliated cells are rare, poorly developed and the cilium does not extend past the cuticle. The ultrastructure of the tentacles is discussed in relation to those of other holothurians.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215848
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  • 98
    Electronic Resource
    Electronic Resource
    The ultrastructure of the lung of two newborn marsupial species, the northern native cat, Dasyurus hallucatus, and the brushtail possum, Trichosurus vulpecula (1988)
    Springer
    Cell & tissue research 252 (1988), S. 683-685 
    Details
    ISSN: 1432-0878
    Keywords: Lung ; Ultrastructure ; Marsupial ; Newborn ; Surfactant ; Dasyurus hallucatus, Trichosurus vulpecula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lungs of newborn northern native cats, Dasyurus hallucatus and newborn brushtail possums, Trichosurus vulpecula were examined by both light and electron microscopy. The native cat has a birth weight of 18 mg after a gestation of about 21 days, whereas the brushtail possum weights 200 mg at birth and has a gestation period of 17.5 days. The lungs of the native cat are two large respiratory sacs, with a respiratory lining of squamous cells and surfactant-secreting cells. The capillaries are located within the connective tissue just below this respiratory epithelium. The visceral covering of the lung is formed by squamous cells. The lungs of the possum are composed of numerous large respiratory sacs which are separated by connective tissue septa in which the capillaries are located. The sacs, as in other species, are lined with squamous cells and surfactant secreting cells. It is proposed that the structure of the lung of the newborn marsupial is related more to the size of the newborn rather than to the length of the gestation period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216657
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  • 99
    Electronic Resource
    Electronic Resource
    Vascular response in a non-uterine site to implantation-stage embryos in the rat and guinea-pig: in vivo and ultrastructural studies (1988)
    Springer
    Cell & tissue research 254 (1988), S. 217-224 
    Details
    ISSN: 1432-0878
    Keywords: Implantation ; Embryo ; Ultrastructure ; Vasculature ; Rat (Sprague-Dawley) ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Preimplantation-stage embryos were transferred to the anterior eye chamber of recipient rats and guinea-pigs. After implantation had occurred the influence of the embryo on the iris vasculature was examined ultrastructurally. In both species, the earliest effect of embryonic implantation was an increased stromal oedema. Under increasing embryonic influence the vascular endothelial cells showed an increased number of projections into the vascular lumen, while in the rat, endothelial projections were also found pushing back into the basement membrane. In the rat, the endothelium became very irregular in thickness prior to complete disintegration and loss during more advanced stages of implantation. Rat embryonic trophoblast was found invading iris vasculature, particularly in areas where the iridial endothelium was partially or completely missing. Other cells in the iris, including the stroma, appeared to be less affected. In the guinea-pig, however, trophoblast cells appeared to be capable of invading the vasculature by displacing endothelial cells that still appeared morphologically normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220037
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  • 100
    Electronic Resource
    Electronic Resource
    Morphological, histochemical, and ultrastructural characterization of the accessory cells of neuromasts in the salamander Pleurodeles waltlii (1988)
    Springer
    Cell & tissue research 254 (1988), S. 233-240 
    Details
    ISSN: 1432-0878
    Keywords: Lateral-line sense organs ; Mechanoreceptors ; Supporting cells ; Ultrastructure ; Pleurodeles waltlii (Urodela)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural and histochemical features of the accessory cells of the neuromast of the salamander P. waltlii have been examined. Three types of accessory cells, supporting, mantle, and basal, were found, but only the first 2 are considered in this article. Supporting cells characterized by a highly dilated endoplasmic reticulum occur among and surrounding sensory cells. Mantle cells, morphologically different from the supporting cells, surround the remainder of the neuromast. Both types of accessory cells exhibit histochemically different secretory materials. Our morphological results suggest that both accessory cells contribute to the formation of cupular material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220039
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