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  • Ultrastructure  (410)
  • Scanning electron microscopy  (77)
  • Drosophila melanogaster  (67)
  • Springer  (552)
  • Periodicals Archive Online (PAO)
  • 1975-1979  (552)
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  • 1
    Electronic Resource
    Electronic Resource
    Coquille de l'oeuf de caille: Étude ultrastructurale et cristallographique (1978)
    Springer
    Calcified tissue international 25 (1978), S. 145-159 
    Details
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010763
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural and microanalytical aspects of developing osteodentin in rat incisors (1977)
    Springer
    Calcified tissue international 24 (1977), S. 215-222 
    Details
    ISSN: 1432-0827
    Keywords: Mineralization ; Osteodentin ; Intracellular ; Ultrastructure ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Newly formed osteodentin obtained from the anterior extremities of fetal or young rat incisors was observed by means of electron microscopy and electron probe X-ray microanalysis. Cells related to osteodentin formation frequently showed membrane bound intracellular bodies containing varying amounts of fine, needle-shaped crystals, which were identified as apatite. The intracellular clusters of apatite crystals were extruded from the cells through membrane fusion or cellular degeneration. These extracellular clusters seemed to be gradually incorporated into the mineralizing collagenous matrix, which developed around them. Frequent occurrence of dense, dotshaped or filamentous profiles suggested that the dense bodies seen in the perinuclear regions or in the Golgi area were the sites of crystal formation. Energy dispersive X-ray point analysis showed that the intracellular or extracellular apatite clusters contained sulfur in a concentration higher than was present in the mineralizing collagenous matrix. Furthermore, wave dispersive X-ray line analysis showed that the concentration of sulfur was higher in the osteodentin matrix than in the dentin matrix. The sulfur detected is presumed to be contained in acid mucopolysaccharides, which were distributed more heavily in the osteodentin matrix than in the dentin matrix. On the basis of these data, it was concluded that the unique chemical and structural characteristics of the osteodentin result primarily from the incorporation of apatite clusters of intracellular origin and associated acid mucopolysaccharides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223319
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the biology of fish bone. III. Ultrastructure of osteogenesis and resorption in osteocytic (cellular) and anosteocytic (acellular) bones (1979)
    Springer
    Calcified tissue international 28 (1979), S. 43-56 
    Details
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteogenesis ; Fish bone ; Osteocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The comparative ultrastructure of fish bone osteogenesis and resorption induced by scale removal was described in the osteocytic (cellular-boned)Carassius auratus and the anosteocytic (acellular-boned)Tilapia macrocephala. Osteocytes, present in osteocytic bone, were lacking in anosteocytic bone. In osteocytic bone the osteoblast secreted a collagenous preosseous matrix in which it became enmeshed and then was termed a preosteocyte. When the preosseous matrix mineralized, the preosteocyte was termed an osteocyte and was completely surrounded by bone. In anosteocytic bone the osteoblasts receded from the mineralizing front and never became trapped as osteocytes. During resorption, types A and B resorptive cells, present in both bone types, invaded the matrix and demineralized the osseous zone. These cells were characterized by large amounts of granular endoplasmic reticulum and intracellular inclusions containing crystal-like material. Although functionally similar to mammalian osteoclasts, these cells lacked a characteristic ruffled border and were not multinucleated. The osteocytes of cellular bone did not appear to be involved during demineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441217
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  • 4
    Electronic Resource
    Electronic Resource
    The ultrastructure of the zygospore in Endogone flammicorona Trappe & Gerdemann (1976)
    Springer
    Mycopathologia 59 (1976), S. 117-123 
    Details
    ISSN: 1573-0832
    Keywords: Ultrastructure ; Zygospore ; Mycorrhizal fungus ; Flaming crown
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ultrastructural organization of the spores of the sporocarp of Endogone flammicorona was studied. Two types of organization are described. Initially the spore possessed a vacuolate protoplasm and was bound by two cell wall layers. The spore was surrounded by a hyphal mantle formed of a sheet of vacuolized hyphae with uniformly thin walls. Secondly, although the ultrastructural features of the spore appeared the same, it was now surrounded by a hyphal mantle with unevenly thickened walls (i. e., the so-called flaming crown) due to the gradual and irregular deposition of granules and lamellae. This crown gives the spore its most commonly observed morphological feature and is the preminent character employed taxonomically to speciate Endogone flammicorona Trappe & Gerdemann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493564
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  • 5
    Electronic Resource
    Electronic Resource
    Localization of cells capable of transdetermination in a specific region of the male foreleg disk ofDrosophila (1977)
    Springer
    Development genes and evolution 182 (1977), S. 69-74 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Male foreleg disk ; Capacity of transdetermination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the male foreleg disk ofDrosophila melanogaster the cells capable of transdetermination are clustered in a specific region within the upper half of the disk. Cells outside this region cannot transdetermine under any of the experimental conditions thus far applied. Transdetermination occurs when cells capable of transdetermination are stimulated to a certain extent of additional proliferation. This can be achieved either by exposing these cells at a wound surface of an intact fragment, or by dissociation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848088
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  • 6
    Electronic Resource
    Electronic Resource
    Localized synthesis of specific proteins during oogenesis and early embryogenesis inDrosophila melanogaster (1979)
    Springer
    Development genes and evolution 187 (1979), S. 151-165 
    Details
    ISSN: 1432-041X
    Keywords: Oogenesis ; Embryogenesis ; Two-dimensional gels ; Protein synthesis ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protein synthesis in egg follicles and blastoderm embryos ofDrosophila melanogaster has been studied by means of two-dimensional gel electrophoresis. Up to 400 polypeptide spots have been resolved on autoradiographs. Stage 10 follicles (for stages see King, 1970) were labelled in vitro for 10 to 60 min with35S-methionine and cut with tungsten needles into an anterior fragment containing the nurse cells and a posterior fragment containing the oocyte and follicle cells. The nurse cells were found to synthesize a complex pattern of proteins. At least two proteins were detected only in nurse cells but not in the oocyte even after a one hour labelling period. Nurse cells isolated from stages 9, 10 and 12 follicles were shown to synthesize stage specific patterns of proteins. Several proteins are synthesized in posterior fragments of stage 10 follicles but not in anterior fragments. These proteins are only found in follicle cells. No oocyte specific proteins have been detected. Striking differences between the protein patterns of anterior and posterior fragments persist until the nurse cells degenerate. In mature stage 14 follicles, labelled in vivo, no significant differences in the protein patterns of isolated anterior and posterior fragments could be detected; this may be due to technical limitations. At the blastoderm stage localized synthesis of specific proteins becomes detectable again. When blastoderm embryos, labelled in vivo, are cut with tungsten needles and the cells are isolated from anterior and posterior halves, differences become apparent. The pole cells located at the posterior pole are highly active in protein synthesis and contribute several specific proteins which are found exclusively in the posterior region of the embryo. In this study synthesis of specific proteins could only be demonstrated at those developmental stages which are characterized by the presence of different cell types within the egg chamber, while no differences were detected when stage 14 follicles were cut and anterior and posterior fragments analyzed separately. The differences in the pattern of protein synthesis by pole cells and blastoderm cells indicate that even the earliest stages of determination are reflected by marked changes at the biochemical level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848268
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  • 7
    Electronic Resource
    Electronic Resource
    Étude en microscopie électronique et par cytophotométrie à balayage de la structure et de la distribution de la chromatine dans les noyaux des cellules cartilagineuses deTriturus cristatus âgés au cours de la régénération (1978)
    Springer
    Development genes and evolution 184 (1978), S. 195-211 
    Details
    ISSN: 1432-041X
    Keywords: Ultrastructure ; Scanning cytophotometry ; Chromatin ; Chondrocytes ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les cellules cartilagineuses des membres postérieurs deTriturus cristatus en régénération après amputation, ont été étudiées en microscopie électronique et par cytophotométrie à balayage. Nous nous sommes intéressés à la structure et à la distribution de la chromatine mais aussi à différents organites cytoplasmiques. Dans l'étude de cytophotométrie à balayage, la chromatine a été considérée à travers son constituant majeur, l'ADN, coloré par la réaction de Feulgen. Au cours de la régénération du membre, l'hétérochromatine initialement condensée, essentiellement accolée à la membrane nucléaire se décondense. Les vacuoles du cytoplasme, caractéristiques des animaux âgés par rapport aux animaux jeunes, disparaissent, les mitochondries et le reticulum endoplasmique rugueux deviennent plus abondants. Les caractéristiques nucléaires de l'activation cellulaire apparaissent précocement, précédent les modifications cytoplasmiques et conduisent à des cellules en tous points identiques aux cellules d'animaux jeunes en dehors de tout processus régénératif. Cette phase d'euchromatisation et de restructuration cytoplasmique est peut-être nécessaire à l'accroissement d'activité métabolique et à la division cellulaire qui suivent. Son déroulement peut expliquer tout au moins le ralentissement de la régénération observé chez les animaux âgés par rapport aux animaux jeunes.
    Notes: Summary Cartilaginous cells of aged newts (Triturus cristatus) were studied during hind limb regeneration. The electron microscope was used to study the structure and distribution of chromatin in the cell nuclei, while the DNA content of the chromatin was measured by means of a scanning cytophotometer. Changes in the ultrastructure of the cytoplasm during regeneration were also studied. It was observed that the structure and distribution of chromatin in the activated cell is greatly modified. In the non-activated cell of the aged newt, the chromatin is found highly condensed and distributed peripherally close to the nuclear membrane. In contrast, in the activated cells, the chromatin is much less condensed and is distributed throughout the nucleus. Moreover, cytoplasmic vacuoles, found only in the non-activated aged cells, disappear and an increase in the mitochondria and rough endoplasmic reticulum is also observed. Changes in the nuclear structure are observed prior to the cytoplasmic modifications. It is interesting to note that the process of activation induces structural changes in the aged cells which make these cells appear to be structurally identical to the young cells. This process of rejuvenation takes 3–5 days in the newt. We suggest that these structural changes of the chromatin and cytoplasm in the aged cells are necessary to increase the metabolic activity which precedes cell division. It may also explain why regeneration takes a longer time in the aged animals than in the young ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848254
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic analysis of pattern-formation in the embryo ofDrosophila melanogaster (1977)
    Springer
    Development genes and evolution 183 (1977), S. 249-268 
    Details
    ISSN: 1432-041X
    Keywords: Pattern-formation ; Embryogenesis ; Maternal-effect mutants ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationbicaudal (Bull, 1966) causes embryos to develop a longitudinal mirror image duplication of the posteriormost abdominal segments, while head and thorax are missing. These embryos occur with varying frequencies among eggs laid by mutant females, irrespective of the paternal genotype. Recombination and deletion mapping indicate thatbicaudal (bic) is a recessive, hypomorphic, maternal-effect mutation mapping at a single locus on the second chromosome ofDrosophila melanogaster close tovg (67.0±0.1). The frequency of bicaudal embryos depends on the age of the mother, her genetic constitution and the temperature at which she is raised. Best producers are very young females hemizygous forbic (bic/Df(2)vg B ) at 28° C. Under these conditions 80% to 90% of the eggs which differentiate can show the bicaudal embryo phenotype. Upon ageing of the mother the frequency of bicaudal embryos declines rapidly, and most of the eggs develop the normal body pattern. Temperature shift experiments suggest a temperature-sensitive period at the onset of vitellogenesis. The mutation causes several types of abnormalities in the segment pattern of theDrosophila embryo, which are interpreted as various degrees of expression of the mutant character. The most frequent abnormal phenotype is the symmetrical bicaudal embryo with one to five abdominal segments duplicated. Less frequent are asymmetrical types, in which the smaller number of segments is always in the anterior reversed part. Other phenotypes are embryos with missing or rudimentary heads, and embryos with irregular gaps in the segment pattern. In bicaudal embryos, the pole cells, formed at the posterior pole of the egg prior to blastoderm formation, are not duplicated at the anterior. The significance of thebicaudal phenotypes for embryonic pattern-formation inDrosophila is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867325
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  • 9
    Electronic Resource
    Electronic Resource
    The cytoplasmic architecture of the egg cell ofSmittia spec. (Diptera, Chironomidae) (1977)
    Springer
    Development genes and evolution 183 (1977), S. 233-248 
    Details
    ISSN: 1432-041X
    Keywords: Cytoplasmic architecture ; Ultrastructure ; Insect egg ; Pattern formation ; Yolk ; Cytoplasma-Architektur ; Ultrastruktur ; Insekten-Ei ; Musterbildung ; Dotter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Das Ei der ZuckmückeSmittia spec. wurde licht- und elektronenmikroskopisch untersucht. Die vorliegende Arbeit beschreibt den Bau des Periplasmas und des Dotter-Endoplasma-Systems vor Bildung der Polzellen. 2. Das Periplasma, nach außen vom Oolemm und einer mehrschichtigen Eihülle begrenzt, besteht aus einer ribosomenreichen cytoplasmatischen Matrix, in die vor allem Mitochondrien und ER-Zisternen, wenig annulate lamellae und gelegentlich Golgi-Apparate eingelagert sind. Mikrotubuli wurden nur selten nachgewiesen. Öfters sind Anhäufungen einer dichten granulierten Substanz zu beobachten, die in ihrer Struktur dem Oosom-Material ähnelt. 3. Das Dotter-Endoplasma-System stellt ein Netzwerk aus Cytoplasma dar, in das Proteid-Dotterkugeln, Lipidtröpfchen sowie Glycogen-Anhäufungen eingelagert sind. Das Endoplasma, das sich zu 3–7 Plasma-Inseln erweitern kann und unmittelbar in das Periplasma übergeht, besteht wie dieses aus einer cytoplasmatischen Matrix und enthält die gleichen Zellelemente wie das Periplasma. Rosettenförmige Membran-Strukturen werden als “nuclear envelope organizing center” gedeutet. 4. Drei der sorgfältig analysierten Eier enthielten je 2 Kerne; sie lagen in Plasma-Inseln in der hinteren Eihälfte. 5. Sowohl im Periplasma wie im Dotter-Endoplasma-System sind alle Zellelemente unregelmäßig verteilt. Eine besondere Anordnung oder Zonierung ist nicht zu erkennen. 6. Die räumliche Verteilung der erfaßten Eikomponenten liefert keine Hinweise auf eine Funktion dieser Komponenten als Determinanten für die embryonale Musterbildung.
    Notes: Summary 1. Eggs of the midgeSmittia were investigated by light microscopy and transmission electron microscopy. This paper describes elements and architecture of periplasm and yolk endoplasm before the formation of pole cells. 2. The periplasm is coated externally by the oolemma and a multilayered egg shell. The periplasm consists of a cytoplasmic matrix rich in ribosomes; it contains mitochondria and ER cisternae, some annulate lamellae and an occasional Golgi complex. Microtubuli were demonstrated only rarely. Accumulations of a dense granulated substance resembling in its structure the oosome material were frequently observed. 3. The yolk endoplasm is a cytoplasmic network embodying proteid yolk particles, lipid droplets and accumulations of glycogen. The endoplasm is continuous with the periplasm and shows the same cell constituents. It may form between 3 and 7 cytoplasmic islands free of yolk particles. Rosette-shaped membranous structures in the yolk endoplasm are interpreted as nuclear envelope organizing centres. 4. Three carefully analysed eggs contained 2 nuclei each. both nuclei were situated in the posterior egg half. 5. Periplasm and yolk endoplasm are characterized by random distribution of cell elements. No zonation or special accumulations could be recognized. 6. The spatial distribution of the egg components studied did not indicate that any of these components could function as a determinant in embryonic pattern formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867324
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructure of a fertilized barnacle egg (Pollicipes polymerus) with peristaltic constrictions (1977)
    Springer
    Development genes and evolution 181 (1977), S. 333-355 
    Details
    ISSN: 1432-041X
    Keywords: Barnacle eggs ; Constriction rings ; Microfilaments ; Ultrastructure ; Peristalsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The egg ofPollicipes polymerus, the common intertidal gooseneck barnacle, has been studied by electron microscopy. Constriction rings, similar to the contractile rings of cleaving cells and polar lobes, move unidirectionally from the animal to the vegetal pole of newly fertilized eggs. This is referred to as peristaltic constriction. The present paper describes the fine structure of the egg during first polar body formation and peristalsis. 2. During formation of the polar body, dense bodies are produced by the Golgi and extracellular plaques are observed. Thin microfilaments (40–60 Å) are in the egg adjacent to the polar body. 3. In eggs undergoing peristalsis, the appearance of extracellular spheres, flocculent material and filaments is observed. Intracellularly large numbers of multivesiculate bodies, glycogen granules, mitochondria and protein-carbohydrate and lipid yolk bodies are seen at the level of constriction. 4. Thin microfilaments are found in the cortical area of newly-fertilized eggs exclusively in peristaltic constriction rings. Filaments are oriented primarily in a meshwork, although circumferentially-oriented filaments are also found in rings near the vegetal pole. Microvilli extend into the space created between a constriction and the elevated egg membrane. 5. A model is proposed to explain the peristalsis in this species. It is suggested that information from a pacemaker region activates peristalsis by affecting filament polymerization and orientation. One function of peristalsis may be elongation of the egg from a sphere to an ovoid, although other possibilities such as elevation of the egg membrane, segregation of the lipid yolk to the vegetal pole and predetermination of the first cleavage plane are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848060
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  • 11
    Electronic Resource
    Electronic Resource
    Ultrastructure of collagen in sea urchin embryos (1979)
    Springer
    Development genes and evolution 186 (1979), S. 65-70 
    Details
    ISSN: 1432-041X
    Keywords: Sea urchin ; Embryo ; Collagen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Collagen fibrils with a main period banding of 610 Å and 220 Å in width were observed in the blastocoel of 72-h embryos of the sea urchin,Strongylocentrotus purpuratus. Non-striated fibrils of 50 Å diameter were also observed. The collagen is seen in highest concentration in the vicinity of mesenchyme cells which are richly endowed with endoplasmic reticulum and secretory vesicles. A role for collagen in cell attachment, orientation and spicule formation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848108
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  • 12
    Electronic Resource
    Electronic Resource
    Detection of clones in the nervous system ofDrosophila melanogaster (1977)
    Springer
    Development genes and evolution 183 (1977), S. 165-169 
    Details
    ISSN: 1432-041X
    Keywords: Clones ; Nervous system ; Shibire ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitotic recombination was induced, by X-irradiation at the blastoderm stage, in flies heterozygous for one of the temperature-sensitive paralytic mutationsshibire andtp-2. The results show that these mutations can be used to detect the presence of clones in the central nervous system through the temperature-sensitive paralysis of individual legs. Mitotic recombination can also be used to examine the effects of these mutations in the peripheral nervous system; shibire is thus shown to affect the function of sensory neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848786
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  • 13
    Electronic Resource
    Electronic Resource
    Isozymic patterns and functional states of cell lines ofDrosophila melanogaster cultured in vitro. II (1976)
    Springer
    Development genes and evolution 180 (1976), S. 107-119 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Cell lines ; Isoenzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our previous isoenzyme investigation ofDrosophila melanogaster cell lines in vitro has been completed with twelve further enzyme systems. The “enzyme profiles” seem to be in good agreement with a previous hypothesis concerning the precise origin of these cell lines (probably from imaginal discs or nervous tissues). Our results have been summarized with reference to the biochemical genetic map ofDrosophila melanogaster in order to consider a possible functional organization of the genome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848101
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  • 14
    Electronic Resource
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    A study of the female germ line in mosaics ofDrosophila (1978)
    Springer
    Development genes and evolution 184 (1978), S. 41-56 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Female germ line ; Mosaics ; Stem cell divisions ; Metafemale ; Sterility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our report presents an analysis of the development and dynamics of the female germ line inDrosophila. Females were produced that were mosaic either for attached-X chromosomes $$(\widehat{XX})$$ and a ring-X (triplo-X-diplo-X), or for $$\widehat{XX}$$ and a marked Y-chromosome $$(\widehat{XX}/Y - \widehat{XX}/O)$$ . The germ-line and genitalia of these females were analysed by direct microscopic observation or by examination of the progeny. Eggs derived from triplo-X germ cells were hardly capable of supporting development, with most of the zygotes dying during embryonic development. The analysis of the germ line was therefore carried out mainly by direct observation of histochemically stained developing oocytes in the ovaries of mosaic females. The total germ cell population of both ovaries of a female was mosaic in 22–29% of the tested animals. From this frequency of mosaicism we estimated the number of functional primordial germ cells to be betwen 3 and 6 cells at the blastoderm stage. At this stage the cell lineages for the left and right ovary are not yet separated. The germ cell population of individual ovarioles was frequently mosaic which shows that the few stem cells in an ovariole are recruited as a group and are not clonal descendants of a single ancestor cell per ovariole. An analysis of the sequential pattern of oocyte-nurse cell cysts in mosaic ovarioles revealed that neighbouring cysts tend to be of the same genotype. This suggests that the stem cells of the adult ovaries preferentially divide in bursts, one of them giving rise to two, three and sometimes even more cystocytes in a row. In addition, the foci for lethality and sterility of the triplo-X condition were determined. Non-mosaic triplo-X females (metafemales) are hardly viable and invariably sterile. Using our mosaics, the focus forlethality could be mapped to a region very near the ventral prothoracic discs. The focus forsterility resides in the genitalia, since flies with triplo-X genitalia never laid any eggs, regardless of the genotype of their ovaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848668
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  • 15
    Electronic Resource
    Electronic Resource
    Rudimentary mutants ofDrosophila melanogaster (1979)
    Springer
    Development genes and evolution 187 (1979), S. 167-177 
    Details
    ISSN: 1432-041X
    Keywords: Pyrimidine biosynthesis ; rudimentary mutants ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The X-linkedrudimentary (r) mutants ofDrosophila melanogaster are pyrimidine auxotrophs and require exogenous pyrimidines (Nørby, 1970; Falk, 1976). We have established a set ofrudimentary cell lines that are derived from embryos, homozygous for eitherr 1 orr 36. The enzymatic activities of the pyrimidine synthesizing enzymes were measured in the mutant lines. We have further investigated the nutritional requirements of the mutant cells in vitro by using a pyrimidine free culture medium. Ther 1 cell lines were found to express 3–7%dihydroorotase (DHOase) activity as compared to a wildtype cell line. Reducedaspartate transcarbamylase (ATCase) activity was measured in somer 1 cell lines whereas wildtypecarbamylphosphate synthetase (CPSase) activity is expressed in allr 1 cell lines. Ther 36 cell line expresses wildtype activity ofDHOase andCPSase. ATCase activity was found to be reduced to 10% of the wildtype activity. The mutant cell lines do not proliferate in pyrimidine free minimal medium and cell proliferation is obtained by the addition of crude RNA. Proliferation of ther 1 cells is restored by the supplementation of the minimal medium withdihydroorotate whereas proliferation of ther 36 cells is restored by supplementation with eitherdihydroorotate orcarbamylaspartate. The results demonstrate that therudimentary phenotypesr 1 andr 36 are expressed at the cellular level and that the two mutant cell types behave as cellular pyrimidine auxotrophs in vitro.
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    URL: http://dx.doi.org/10.1007/BF00848269
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  • 16
    Electronic Resource
    Electronic Resource
    Retention of the differentiated state by larvalXenopus liver cells in primary culture (1978)
    Springer
    Development genes and evolution 185 (1978), S. 235-248 
    Details
    ISSN: 1432-041X
    Keywords: Liver ; Primary culture ; Ultrastructure ; Albumin synthesis ; Xenopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron microscopic analysis of primary cultures derived from larvalXenopus liver has shown that these cells, although they form only two-dimensional aggregates, retain and presumably also develop structural characteristics typical of liver parenchyma cells, such as bile canaliculi with microvilli and epithelial junctional complexes. As judged from structural criteria, primary cultures contain 80–90% hepatocytes. In contrast to the intact tissue, primary cultures showed excessive development of microfilaments, however. Incorporation of labeled amino acids has revealed further that the capacity for protein synthesis is maintained in culture and that synthesis of liverspecific protein albumin is maintained in vitro, even in liver cultures derived from thyrostatic tadpoles. This latter result suggests that initiation of albumin synthesis in the larval liver is probably not dependent upon thyroid hormones but rather reflects the protodifferentiated state of this tissue.
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    The effect of fat body on the differentiation in vitro of wing imaginal discs ofDrosophila melanogaster (1976)
    Springer
    Development genes and evolution 180 (1976), S. 73-77 
    Details
    ISSN: 1432-041X
    Keywords: Ecdysones ; Imaginal discs ; Fat body ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of suboptimal levels of α-ecdysone on the differentiation in vitro ofDrosophila melanogaster wing discs was enhanced by the addition of larval fat body to the cultures. However, similar experiments with β-ecdysome showed no enhancement. It is suggested that a partial conversion of α-ecdysone to β-ecdysone by the fat body may well account for these results.
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    URL: http://dx.doi.org/10.1007/BF00848885
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    SEM analysis of amphibian mesodermal migration (1977)
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    Development genes and evolution 181 (1977), S. 31-40 
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    ISSN: 1432-041X
    Keywords: Cell migration ; Mesoderm ; Gastrulation ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At the end of gastrulation, the lateral mesoderm of amphibian embryos migrates ventrally between the ectoderm and the endoderm. The present study is an examination of the morphology of the leading cells of the mesodermal sheet and of the substratum over which they move (the inner surface of the ectoderm). The cells of the leading edge of the mesoderm are generally round, with very short and narrow flattened projections in the forward direction. These projections do not have a “ruffled” morphology, regardless of whether fixation is carried out before or after the ectoderm and mesoderm are dissected away from the endoderm. The inner surface of the ectoderm is covered with fine (450–500A) filamentous extracellular material and the ectoderm cells sometimes extend cytoplasmic processes (approx. 0.1 μ wide) onto the leading surface of the mesoderm or onto adjacent ectoderm cells. These studies indicate that the morphology of cell migration in amphibians is closer to that seen inFundulus than to that characteristic of chick or mammalian cells.
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    URL: http://dx.doi.org/10.1007/BF00857266
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    Developmental potentials of the cells of the male foreleg disc ofDrosophila (1977)
    Springer
    Development genes and evolution 181 (1977), S. 309-320 
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    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Male foreleg disc ; Pattern regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The developmental potentials of the four quadrants of the male foreleg disc ofDrosophila melanogaster were analysed by culturing excised quadrants for 3 days and 10 days in adult hosts prior to metamorphosis. 2. The cultured pieces underwent different types of pattern regulation in a circular direction. The upper medial piece was able to regenerate the missing structures of the disc, thus confirming the findings of earlier reports. The three remaining pieces could undergo pattern duplication in mirror-image symmetry. The lower medial piece revealed in addition a slight capacity for regeneration from the vertical cut surface. 3. The duplicating pieces differed markedly in their frequencies of pattern duplication: duplications occurred with very high frequencies in lower medial pieces, with intermediate frequencies in upper lateral pieces, and with very low frequencies in lower lateral pieces. 4. Both lower lateral and upper lateral pieces underwent a progressive loss of most markers with increasing culture time. 5. Claws were regenerated solely by upper medial pieces. 6. Transdetermined structures, too, were encountered only in upper medial pieces. 7. The results are discussed with respect to the two major current models of pattern regulation in imaginal discs, the “gradient model” and the “clock model”. 8. It is suggested that the differences in the frequencies of pattern duplication reflect the unequal spacing of circular positional values within the three duplicating quadrants. Under this assumption the data indicate a progressive decrease in the density of circular positional values with increasing distance from the upper medial quadrant of the disc.
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    URL: http://dx.doi.org/10.1007/BF00848058
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    Ultrastructural changes in the distal wing bud of the chick embryo after removal of the apical ectodermal ridge (1979)
    Springer
    Development genes and evolution 185 (1979), S. 333-346 
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    ISSN: 1432-041X
    Keywords: Chick embryo ; Limb bud ; Ultrastructure ; Cell death
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural changes in the wing bud afterapical ectodermal ridge (A.E.R.) removal was studied to re-examine the issue of distal mesenchymal cell death. The A.E.R. of the right wing bud was removed microsurgically from chick embryos of stages 18 to 22 (HH 1951). The wing buds were examined at three hour intervals up to twelve hours after the operation with light, transmission and scanning electron microscopy. The main findings were: (1) Immediate and temporary shrinkage of the mesenchymal extracellular space 100 to 150 μm and chromatin condensation in the cells 50 to 75 μm from the wound. (2) Death of ectodermal and mesenchymal cells in the immediate vicinity of the wound. (3) Formation of a single squamous-like layer of mesenchymal cells to cover the wound. (4) Occasional evidence of cell death in the distal mesenchyme at later times after the operation. The pattern of cell death observed suggests only a traumatic etiology, and gives little evidence for the postulated developmental significance of cell death following A.E.R. removal.
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    URL: http://dx.doi.org/10.1007/BF00848520
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    Ultrastructure, histology, and innervation of the mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi (1978)
    Springer
    Calcified tissue international 26 (1978), S. 271-282 
    Details
    ISSN: 1432-0827
    Keywords: Shell formation ; Free nerve endings ; Ultrastructure ; Lymnaea stagnalis ; Biomphalaria pfeifferi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi was investigated with histochemical and ultrastructural methods. The mantle edge gland, which is involved in shell formation, consists of the periostracal groove and the belt. This belt appears to be composed of various regions. In the area of the periostracal groove a number of subepithelial gland cell types occur; these release their products into the groove. Between the groove cells ciliated free nerve endings terminate; the corresponding perikarya occur in the subepidermal connective tissue. Also in the posterior belt region free nerve endings were observed between the epithelial cells; in addition, a particular type of subepithelial gland cell was found in this area. The epithelial cells of this part of the belt have the ultrastructural characteristics of ion and water transporting cells; they are probably involved in calcium deposition and resorption. The possible role of the free nerve endings and of the subepithelial gland cells is discussed.
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    URL: http://dx.doi.org/10.1007/BF02013270
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    Growth of embryonic chick tibiae in ovo and in vitro: A scanning electron microscope study (1979)
    Springer
    Calcified tissue international 27 (1979), S. 33-40 
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    ISSN: 1432-0827
    Keywords: Chick embryo ; Bone ; Organ culture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The study describes the ultrastructure of the mineralized portion of chick tibiae from 10 days in ovo to 2 days post-hatch. At 10 days a single mineralized cylinder surrounds the diaphysis. On its outer surface columnar trabeculae join to form ridges parallel to the long axis of the bone. These ridges are covered by another cylinder and form the haversian canals. At 11 days vascular invasion of the marrow cavity occurs and resorption of the endosteal surface begins. This type of periosteal deposition and endosteal resorption is repeated during and subsequent to embryonic development. The mineralized portion of 10-day chick tibiae cultured for 2 days in modified BGJ medium was compared with 10-, 11-, and 12-day tibiae in ovo. Cultured tibiae were similar in length and calcium content to 11-day tibiae in ovo. The form of mineral deposited in ovo and in culture was the same, namely, aggregates of spherical mineral clusters. Differences in culture included the following: (a) few concentric cylinders were deposited as compared with tibiae in ovo; (b) trabeculae were not arranged in rows and ridges in culture; (c) osteocytic lacunae were restricted to bases of trabeculae rather than uniformly distributed as in ovo; and (d) the endosteal surface of tibiae in culture appeared etched.
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    Correlation of freeze-fracture and scanning electron microscopy of epiphyseal chondrocytes (1978)
    Springer
    Calcified tissue international 26 (1978), S. 237-241 
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    ISSN: 1432-0827
    Keywords: Epiphyseal chondrocytes ; Freezefracture ; Scanning electron microscopy ; Cell processes ; Membrane particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Chondrocytes in epiphyseal cartilage were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using freeze-fracture techniques. Freeze-fracture replicas showed large numbers of fingerlike, 0.11–0.15 μm diameter, projections from the chondrocyte surface, with numerous 95–180 Å diameter intramembranous particles associated with both the cell membrane surface and these projections. With SEM, these cytoplasmic projections were also obvious, but appeared collapsed into clusters of globular-shaped projections on the surface of the chondrocytes. With freeze-fracture techniques, in which shrinkage artifacts were essentially eliminated, the cytoplasmic projections were often seen in intimate contact with the extracapsular matrix. However, with chondrocytes prepared by both SEM and conventional TEM, there was evidence of shrinkage, the cytoplasmic projections having little contact with the extracapsular matrix. These findings show that the cytoplasmic processes are not artifacts of tissue processing and provide morphological evidence in support of the hypothesis that matrix vesicles are of cellular origin.
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    Scanning electron microscopical study on the fluorosis of enamel in rats (1978)
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    Calcified tissue international 25 (1978), S. 75-83 
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    ISSN: 1432-0827
    Keywords: Rat ; Fluorosis ; Enamel ; Scanning electron microscopy ; Low temperature incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.
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    Ultrastructural damage due to freezing followed by thawing in shoot meristem and leaf mesophyll cells of tall fescue (Festuca arundinacea Schreb.) (1977)
    Springer
    Planta 134 (1977), S. 159-168 
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    ISSN: 1432-2048
    Keywords: Festuca ; Frost damage ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tillers of Festuca arundinacea Schreb. were subjected to-8°C in a bath of methylated spirits for three-quarters of an hour. They were thawed at room temperature and some material taken from the shoot apical meristem and leaf blade for electron microscopy. Similar material was taken from control plants for electron microscopy. Nine tillers subjected to-8°C and thawed subsequently failed to regrow. Nine control tillers regrew. All the treated meristem cells and about half the treated leaf mesophyll cells were extensively altered. Their nuclei were contracted, organelles were swollen or partly disrupted, plasmalemma and nuclear membranes were broken or absent and vacuoles were sometimes disrupted. Strongly osmiophilic material accumulated in the vicinity of membranes. About half the leaf mesophyll cells differed from the control mesophyll cells only in having more spherosomes and narrower thylakoids. Parallels with other ultrastructural studies of stress damage and the indications the results give of possible primary damaging events are discussed.
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    Structure and association of wall fibrils produced by regenerating tobacco protoplasts (1979)
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    Planta 146 (1979), S. 203-210 
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    ISSN: 1432-2048
    Keywords: Cellulose ; Microfibrils ; Negative staining ; Nicotiana ; Protoplasts ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study has been made of the wall fibrils produced by tobacco protoplasts, using scanning electron microscopy in conjunction with negative staining. It has been shown that the fibres seen in scanning electron microscopy correspond to aggregates of microfibrils. These aggregates are only visible where they are lifted clear of the protoplast surface. Negative staining of fixed protoplasts shows that the aggregation of microfibrils into the fibres visible in scanning electron microscopy is probably produced by air-drying. Gentle disruption of microfibrils produces both random broken fragments and bundles of short pieces of fibrillar material about 60 nm in length. This material is present in undisrupted young walls, but not in undisrupted older walls. The microfibrils in young walls seem much more fragile and liable to breakage than those in older walls. These results are discussed in terms of the interpretation of scanning electron microscope images and the mechanism of cellulose microfibril formation by higher plants.
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    Early embryogenesis in Tropaeolum majus L.: Diversification of plastids (1976)
    Springer
    Planta 133 (1976), S. 15-19 
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    ISSN: 1432-2048
    Keywords: Tropaeolum, Embryogenesis ; Differentiation ; Plastids ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogeny in the nasturtium is characterized by the development of a large, tripartite suspensor and storing cotyledons. A light and electron microscopic study revealed an early diversification of the plastids in the various regions of the suspensor and the embryo proper. Amyloplasts are found in the developing cotyledons of the heart-like embryo, while chloroplasts occur within the meristematic part of the embryo and the adjacent portion of the suspensor. The cells between the meristem and the storing cotyledons display undifferentiated leukoplasts, whereas leukoplasts with an electron-dense matrix occur in the basal cell mass of the embryo-suspensor. Etioplasts develop in several cells of the placental haustorium of the suspensor. The carpel haustorium shows rather undifferentiated leukoplasts, which are transformed into electron-dense plastids during autolysis of the suspensor. This early plastidal differentiation in discussed with respect to its control and functional significance.
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    Unusual cell structures in tumor-like formations of Gracilaria (Rhodophyta) (1976)
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    Archives of microbiology 108 (1976), S. 167-174 
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    ISSN: 1432-072X
    Keywords: Red algae ; Gracilaria verrucosa ; Tumor-like formations ; Ultrastructure ; Viruses ; Endoplasmic reticulum ; Plastids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper deals with electron microscopic observations on cultivated plants of the marine red alga Gracilaria verrucosa which developed simple galls; also sea collected material, without galls, had been studied. The galls showed unusual but characteristic cell structures, caterpillar-like bodies, containing rows of fusiform bodies. These were found mostly in the cytoplasm near the plastids, in one case connected with the endoplasmic reticulum, occasionally even inside the nucleus, and are described here, as far as we know, for the first time. It does not seem probable that the caterpillar-like bodies represent mitochondria or bacteria, but the hypothesis that fusiform bodies are related to virus-like structures is discussed. The normal tissues as well as the gall tissue of the laboratory plants contained, besides plastids typical for the red algae, another type of plastids characterized by tubular thylakoids.
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    URL: http://dx.doi.org/10.1007/BF00428947
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    Mycoparasitic relationships (1977)
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    Archives of microbiology 111 (1977), S. 207-224 
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    ISSN: 1432-072X
    Keywords: Host-parasite relationships ; Ultrastructure ; Papillae ; Infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mode of attack and the infection structures of the necrotrophic mycoparasite, Pythium acanthicum, as well as the responses of various fungal hosts to parasitism were studied using both electron and light microscopy. Many taxonomically distinct fungal hosts were used, though Phycomyces blakesleeanus, Pythium aphanidermatum, Rhizoctonia solani and a basidiomycete identified as Corticium sensu lato were studied in greatest detail. Parasitism was by direct penetration of the fungal host without appressorium formation by the parasite. The host's cells responded to contact by P. acanthicum by forming papillae. The morphological features of the papillae varied with the particular host. In P. blakesleeanus they were comprised of vesicles and segments of cytoplasm entrapped in a fibrillo-granular matrix, while in R. solani and the Corticium basidiomycete they contained considerable amounts of electron-opaque and electron-translucent material. Evidence for both mechanical and enzymatic penetration of the host fungi by the parasite are presented. Details of host wall and septum penetration by the parasite are presented using time-lapse light microscopy with in vivo systems. Many of these stages of parasitism were examined ultrastructurally. Some comparisons of these mycoparasitic relationships are discussed in relation to what is known from the literature about phytoparasitic interactions.
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    Localization of α-galactomannan on the surface of Schizosaccharomyces pombe cells by scanning electron microscopy (1977)
    Springer
    Archives of microbiology 112 (1977), S. 123-126 
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    ISSN: 1432-072X
    Keywords: Bandeiraea simplicifolia ; Schizosaccharomyces pombe ; Colloidal gold ; Cytochemistry ; α-Galactomannan-lectin ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Galactomannan was localized by scanning and transmission electron microscopy on the cells and cell walls of Schizosaccharomyces pombe. The markers were prepared from colloidal gold granules labelled with an α-galactopyranosyl-binding lectin isolated from the seeds of Bandeiraea simplicifolia. Part or all of this α-galactomannan was present in the outer layer of the cell wall and was uniformly distributed even on the fission scars.
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    Gametangial development in Allomyces macrogynus (1977)
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    Archives of microbiology 113 (1977), S. 163-172 
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    ISSN: 1432-072X
    Keywords: Allomyces ; Phycomycete ; Ultrastructure ; Gametangial differentiation ; Autophagy ; Gamma bodies ; Multivesicular bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of gametangial development in Allomyces macrogynus was determined from longitudinal sections of gametophytic hyphae at stages of differentiation from vegetative apices at time zero to fully cleaved gametangia at about 150 min. Whereas vegetative hyphae show an apical clustering of mitochondria, cytoplasmic vesicles and microtubules, this arrangement was sharply altered in early development. Mitochondria were evenly redistributed, apical vesicles and microtubules disappeared, and autophagic vacuoles became prominent. Subsequently, electron-dense granules and microbody/lipid droplet complexes became evident and later, during gamete cleavage, developed into gamma bodies and side-body complexes respectively. Meanwhile cytoplasmic vesicles were involved in exit papilla formation. The significance of autophagic vacuoles and multivesicular bodies is discussed.
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    Dorsal-ventral differentiation in Simonsiella and other aspects of its morphology and ultrastructure (1977)
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    Archives of microbiology 113 (1977), S. 197-204 
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    ISSN: 1432-072X
    Keywords: Gliding bacterium ; Simonsiella ; Oral cavity ; Electron microscopy ; Morphology ; Dorsal-ventral differentiation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology and ultrastructure of the aerobic, Gram-negative multicellular-filamentous bacteria of the genus Simonsiella were investigated by scanning and transmission electron microscopy. The flat, ribbon-shaped, multicellular filaments show dorsal-ventral differentiation with respect to their orientations to solid substrata. The dorsal surface, orientated away from the substrate, is convex and possesses an unstructured capsule. The ventral surface, on which the organisms adhere and glide, is concave and has an extracellular layer with fibrils extending at right angles from the cell wall. The cytoplasm in the ventral region contains a proliferation of intracytoplasmic membranes and few ribosomes in comparison to the cytoplasm in other parts of the cell. Centripetal cell wall formation is asymmetrical and commences preferentially in the ventral region. Quantitative differences in morphology and cytology exist among selected Simonsiella strains. Functional aspects of this dorsalventral differentiation are discussed with respect to the colonization and adherence of Simonsiella to mucosal squamous epithelial cells in its ecological habitat, the oral cavities of warm-blooded vertebrates.
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    Two unicellular cyanobacteria which reproduce by budding (1977)
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    Archives of microbiology 115 (1977), S. 249-257 
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    ISSN: 1432-072X
    Keywords: Chamaesiphon spp. ; Cyanobacteria ; Reproduction by budding ; Ultrastructure ; Nutritional properties ; DNA base composition ; Fatty acid composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of unicellular cyanobacteria which reproduce exclusively by budding are described and assigned to genus Chamaesiphon.
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    Methanogenium, a new genus of marine methanogenic bacteria, and characterization ofMethanogenium cariaci sp. nov. andMethanogenium marisnigri sp. nov. (1979)
    Springer
    Archives of microbiology 121 (1979), S. 147-153 
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    ISSN: 1432-072X
    Keywords: Methanogenium cariaci ; Methanogenium marisnigri ; Marine methanogenic bacteria ; Ultrastructure ; TaxonomyMethanogenium gen. nov.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new genus of marine methanogenic bacteria and two species within this genus are described.Methanogenium is the proposed genus andMethanogenium cariaci the type species. Cells of the type species are Gram-negative, peritrichously flagellated, irregular cocci with a periodic wall surface pattern. Colonies formed by these bacteria are yellow, circular and umbonate with entire edges. The DNA base composition is 52 mol% guanine plus cytosine. Formate or hydrogen and carbon dioxide serve as substrates for growth. Cells ofMethanogenium marisnigri are of similar shape but smaller diameter thanM. cariaci. The colonies ofM. marisnigri are convex, and the DNA base composition is 61 mol % G+C. Formate or hydrogen and carbon dioxide are growth substrates. Sodium chloride is required for growth of both methanogens.
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    La paroi cellulaire de Coelastrum (Chlorophycées) (1975)
    Springer
    Archives of microbiology 102 (1975), S. 95-101 
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    ISSN: 1432-072X
    Keywords: Coelastrum ; Chlorococcales ; Chlorophyta ; Ultrastructure ; Cell Wall ; Tubules ; Bristles ; Polymorphism ; Buoancy ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La paroi cellulaire de Coelastrum est généralement composée de trois couches. La couche la plus externe a été plus particulièrement étudiée. Elle est composée de tubules dressées, et porte souvent de longues fibrilles dont le rôle serait de stabiliser l'algue dans son milieu. La morphologie de la paroi cellulaire peut se modifier en fonction du milieu.
    Notes: Abstract The cell wall of Coelastrum is usually composed of three layers. The outermost layer was studied most extensively. It consists of erect tubules which often bear long bristles whose function may be to stabilize the algae in its environment. The cell wall can modify its morphology according to the environment.
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    Effects of diazepam on photosynthesis, respiration, rubidium uptake, and finestructure of Scenedesmus obliquus in synchronous cultures (1975)
    Springer
    Archives of microbiology 102 (1975), S. 129-137 
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    ISSN: 1432-072X
    Keywords: Diazepam ; Benzodiazepines ; Scenedesmus ; Ultrastructure ; Photosynthesis ; Respiration ; Rubidium Uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of diazepam (Valium) on photosynthesis, chlorophyll/photosynthesis ratios, respiration, uptake of rubidium ions, and ultrastructure of Scenedesmus obliquus synchronized by a light-dark regimen of $$14:\overline {10}$$ hrs were determined. 80 and 160 μM diazepam, added to the nutrient medium at the start of the light-dark change (i.e., start of the cell cycle) gradually reduced rates of photosynthesis below the initial rates from the beginning of the experiment. Contents of chlorophyll, however, remained nearly unaffected. Consequently, the diazepam-treated cells had a higher chlorophyll/photosynthesis ratio—also with regard to respiration in order to calculate the gross photosynthesis. The occurrence of photorespiration cannot be assumed. The net influx or rubidium was slightly reduced by 100 μM diazepam 0.5 and 2.0 hrs after the start of the cell cycle and was strongly inhibited after 5 to 14 hrs. 80 and 160 μM diazepam caused separation of thylakoids, formation of giant mitochondria and enlargement of vacuoles. The results are discussed and it is finally suggested that diazepam acts on different membrane systems. Furthermore an ATP deficiency cannot be excluded.
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    Ultrastructural changes occurring during germination and outgrowth of spores of the thermophile Bacillus acidocaldarius (1975)
    Springer
    Archives of microbiology 102 (1975), S. 155-161 
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    ISSN: 1432-072X
    Keywords: Bacillus acidocaldarius ; Spores ; Germination ; Thermophile ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spores of the thermophilic, acidophilic, Bacillus acidocaldarius were covered by a thick outer coat and a laminated inner coat (5.5 nm periodicity). Small membranous vesicles were present in the spore core and they disappeared as germination proceeded. After depolymerization of the cortex, and a 30% increase in spore diameter, a localized gap appeared in the laminated inner coat only. This inner coat gap was narrow and could be the whole length of the spore. The germ cell appeared to grow, or to be pushed towards the inner coat gap, at which stage the outer coat disappeared in the same localized area. As the vegetative cell grew out the spore coat fell away, with loose cortical material still attached to it. The young germ cell developed a large spherical electron dense inclusion body in the cytoplasm, at the same time as the ribosomal and nuclear areas became distinct.
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    An ammonia-oxidizing bacterium, Nitrosovibrio tenuis nov. gen. nov. sp. (1976)
    Springer
    Archives of microbiology 108 (1976), S. 105-111 
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    ISSN: 1432-072X
    Keywords: Ammonia oxidizing bacterium ; Nitrosovibrio tenuis ; Isolation ; Morphology ; Ultrastructure ; Physiology ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ammonia-oxidizing, autotroph growing, slender, curved rod was isolated from the soil of Hawaii. It is well distinguishable from any other nitrifying bacteria thus far described by their morphology. The cells are 1.1–3.0 μm long and 0.3–0.4 μm wide. They are motile by means of 1–4 subpolar to lateral flagella. In contrast to most of the ammonia-oxidizing bacteria the isolated vibrio is void of an extensive cytomembrane system. To categorize this not yet described species we propose to create the new genus Nitrosovibrio and to classify the isolated strain as Nitrosovibrio tenuis.
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    Micromorphology of Gram-negative hydrogen bacteria (1977)
    Springer
    Archives of microbiology 114 (1977), S. 93-100 
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    ISSN: 1432-072X
    Keywords: Ultrastructure ; Micromorphology ; Gram-negative hydrogen bacteria ; Flagellation ; Flagellar fine structure ; Pili
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell morphology, the arrangement and fine structure of flagella and the piliation of the following Gram-negative aerobic hydrogen bacteria have been studied: Alcaligenes eutrophus, Alcaligenes paradoxus, Alcaligenes ruhlandii, Pseudomonas flava, Pseudomonas pseudoflava, Pseudomonas palleronii, Pseudomonas facilis, Aquaspirillum autotrophicum, Paracoccus denitrificans, Corynebacterium autotrophicum, and strains MA 2 and SA 35. The identity of the bacteria was examined by their substrate spectra and type of flagellation. Three types of flagellar fine structure were differentiated. The presence of pili was noted in strains of Alcaligenes paradoxus, Pseudomonas flava, P. pseudoflava, P. palleronii, and P. facilis.
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    The effect of aminopterin (4-amino folic acid) on growth and cell division of fermentative versus oxidative yeasts (1977)
    Springer
    Archives of microbiology 113 (1977), S. 293-302 
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    ISSN: 1432-072X
    Keywords: Aminopterin ; Saccharomyces cerevisiae ; Polyploid ; Oxidative-fermentative yeast ; Ultrastructure ; Bioassay ; Synchrony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a related brewing study detailed characteristics of fermentations displaying effective yeastaminopterin interaction were presented. Fermentative yeast types (certain Saccharomyces species and Selenotila intestinalis) proved effective aminopterin reactors whereas oxidative yeasts (certain Candida, Cryptococcus, Pichia, Rhodotorula, Saccharomyces, and Trigonopsis species) proved ineffective reactors. In general effective reactors were polyploids characterized by the lack of film or pellicle formation and ineffective reactors the opposite. In stationary fermentations the Fleischmann 139 strain of S. cerevisiae proved a fair reactor. When aerated it proved an ineffective reactor and aminopterin or products there-of stimulated growth. Conversely aeration enhanced aminopterin activity of effective reactor yeasts. The positive effect of biotin on aminopterin activity and the negative effect of yeast extract, L-asparagine, adenine and thymine is shown and compared and contrasted with earlier reported studies. These findings supported by outside data suggest that oxidative yeasts (and bacteria) can readily elicit enzymes capable of inactivating aminopterin whereas fermentative types are lacking in this capability. Finally that past yeast-aminopterin studies were conducted with oxidative yeast types. Advantages of effective aminopterin reactor yeasts to be published elsewhere include improved ultrastructure using KMnO4−OsO4 fixation, a yeast bioassay procedure for detecting aminopterin in plasma and urine, and cell synchronization.
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    A comparative ultrastructural study of the ascospores of some Saccharomyces and Kluyveromyces species (1979)
    Springer
    Archives of microbiology 121 (1979), S. 53-59 
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    ISSN: 1432-072X
    Keywords: Saccharomyces ; Kluyveromyces ; Ultrastructure ; Ascospore wall ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three types of structure of the ascospore wall were found among the haploid Saccharomyces species examined: a warty wall (S. rouxii), a smooth wall with a single electron-light inner layer (S. bailii) and a smooth wall with a double light inner layer (S. montanus, S. florentinus). The latter type also occurred in Kluyveromyces thermotolerans and K. waltii. In K. fragilis spores the wall had a single light inner layer. The taxonomic implications of these findings were discussed.
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    Cell wall enzymatic lysis of the yeast form of Pullularia pullulans and wall regeneration by protoplasts (1975)
    Springer
    Archives of microbiology 104 (1975), S. 271-277 
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    ISSN: 1432-072X
    Keywords: Protoplasts ; Regeneration ; Wall Structure ; Pullularia ; Ultrastructure ; Membrane Splitting ; Aberrant Tubes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the process of degradation of the cell wall of the yeast form of Pullularia pullulans by the lytic system of Micromonospora chalcea samples were withdrawn at different times and observed under phase contrast and electron microscope. The progressive lysis of the walls reveals a fibrillar component inside the apparently amorphous wall. Freeze etched preparations of cells during the formation and regeneration of protoplasts show that the cellular membrane is split and this method allows the smooth external face of the membrane and other internal face covered by particles to be seen. The fact that the smooth face of the membrane is only visible during the preparation or the regeneration of protoplasts and very rarely when intact cells are fractured, suggests a strong adherence between cell wall and this external layer of the membrane. During the regeneration which takes place as in most of the yeasts and moulds, a special study of the extension of the cell wall is made and a possible mechanism for this extension of the regenerated cell wall is proposed.
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    Localization of mannan at the surface of yeast protoplasts by scanning electron microscopy (1976)
    Springer
    Archives of microbiology 109 (1976), S. 9-14 
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    ISSN: 1432-072X
    Keywords: Candida utilis ; Saccharomyces cerevisiae ; Colloidal gold ; Cytochemistry ; Mannan ; Plasma membranes ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The β(1→3)glucanase of Basidiomycete QM 806 was used to prepare Saccharomyces cerevisiae and Candida utilis protoplasts. Plasma membranes isolated from S. cerevisiae contained a small amount of mannose and traces of glucose and ribose. Randomly distributed α-mannan was detected by scanning electron microscopy at the surface of prefixed protoplasts using colloidal gold labelled with Concanavalin A as a marker. C. utilis protoplasts were also marked with anti-mannan antibodies. Again the distribution of mannan was random. This experiment indicated also that plasma membrane mannan has the same immunochemical determinants as cell wall mannan. It is hypothesized that mannan is mainly located in the outer layer of plasma membranes.
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    Mating in Chlamydomonas eugametos (1976)
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    Archives of microbiology 109 (1976), S. 31-35 
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    ISSN: 1432-072X
    Keywords: Scanning electron microscopy ; Chlamydomonas ; Cell agglutination ; Cell fusion ; Flagella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A technique has been developed by which mating gametes of Chlamydomonas eugametos can be studied in the Scanning Electron Microscope. A detailed description of the mating process, from the initial flagellar agglutination until the release of free vis-à-vis pairs, is presented. Flagella appear to agglutinate at random points on their surface. This is followed by a rapid increase of the contact area such that they “line-up” tip to tip. Flagella always exhibit a typical position prior to cell fusion. After cell fusion the flagella of a pair separate rapidly while the female have shortened about 33%. In a vis-à-vis pair the plasma bridge has contracted. The observations are interpreted in terms of a specific reorganization of the sexuale aggregate.
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    Ultrastructure of infection of Cokeromyces recurvatus by Piptocephalis unispora (Mucorales) (1976)
    Springer
    Archives of microbiology 109 (1976), S. 277-288 
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    ISSN: 1432-072X
    Keywords: Ultrastructure ; Mucorales ; Piptocephalis ; Mycoparasitism ; Cokeromyces ; Yeastphase ; Appressorium ; Infection peg ; Penetration ; Haustorium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Infection of the mucoraceous host Cokeromyces recurvatus by Piptocephalis unispora was studied ultrastructurally, using a new technique involving yeast-phase cells of the host to obtain large numbers of infection sites for thin-sectioning. Morphologically, the haustorial apparatus was similar to that of fungi parasitic on higher plants, and comprised an appressorium, a neck region with a collar and a neck ring, and a lobed region surrounded by a sheath matrix enclosed in an extra-haustorial membrane. Penetration of the host by the infection peg probably involved both enzymatic degradation and physical pressure. Reaction of the host to infection is described and the results related to the theory of host infection by haustorial fungal parasites.
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    Isolation of a moderate halophilic ammonia-oxidizing bacterium, Nitrosococcus mobilis nov. sp. (1976)
    Springer
    Archives of microbiology 107 (1976), S. 277-282 
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    ISSN: 1432-072X
    Keywords: Nitrosococcus mobilis ; Ammonia oxidizing bacterium ; Morphology ; Ultrastructure ; Physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ammonia-oxidizing bacterium was isolated from a sample of brackish water (North Sea, Harbour of Husum). It is a motile large coccus 1.5–1.7 μm in diameter. The extensive cytomembrane system occurring as flattened vesicles in the peripheral region of the cytoplasm and as intrusions into the center of the cytoplasm is to be emphasized as a characteristic mark of identification. The lithoauto-trophically growing bacterium turned out to be an obligate halophile. Because of its physiological and morphological properties, we assigned it to the genus Nitrosoccus and propose the name Nitrosococcus mobilis.
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    Origin of sclerotia-like cells in submerged Claviceps purpurea producing clavine alkaloids (1976)
    Springer
    Archives of microbiology 107 (1976), S. 321-327 
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    ISSN: 1432-072X
    Keywords: Claviceps purpurea ; Saprophytic ; Clavine alkaloids ; Ultrastructure ; Extended hyphae ; Blastospores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrathin sectioning of submerged mycelium of Claviceps purpurea Tul. producing clavine alkaloids revealed yeast-like budding resulting in asexual sporesblastospores. These deciduous spores were born by extended hyphal cells and retained the same ultrastructure of cell organelles. Both the extended hyphae and the blastospores resembled the cells of ergot sclerotial tissue. A surface culture of C. purpurea Tul. producing no alkaloids was used as a reference.
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    Micromorphology of Gram-negative hydrogen bacteria (1977)
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    Archives of microbiology 114 (1977), S. 101-110 
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    ISSN: 1432-072X
    Keywords: Ultrastructure ; Micromorphology ; Gram-negative ; Hydrogen bacteria ; Cell envelope ; Cytoplasmic inclusions ; Membranes ; Mesosomes ; Glycogen ; Poly-β-hydroxybutyrate ; Cell wall types
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of the cell envelope, of membrane systems and of cytoplasmic inclusions of Gram-negative aerobic hydrogen bacteria has been studied. The results have been tabulated, and three main groups could be recognized: Group 1: Alcaligenes eutrophus, A. paradoxus, A. ruhlandii, Pseudomonas facilis, P. flava, P. pseudoflava, P. palleronii, and Aquaspirillum autotrophicum; Group 2: “Corynebacterium” autotrophicum and strains MA 2 and SA 35; Group 3: Paracoccus denitrificans. Special structures related to the chemoautotrophic way of life of the hydrogen bacteria were not observed.
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    Disappearence of the intracytoplasmic membranes inRhodopseudomonas sphaeroides (1978)
    Springer
    Archives of microbiology 117 (1978), S. 293-295 
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    ISSN: 1432-072X
    Keywords: Rhodopseudomonas sphaeroides ; Intracytoplasmic membranes ; Membranes ; Ultrastructure ; Bacteriochlorophyll ; Chromatophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic bacterium,Rhodopseudomonas sphaeroides, can be grown phototrophically (light, anaerobiosis), of chemotrophically (dark, aerobiosis). In the first case, it contains intracytoplasmic membranes with photosynthetic pigments. When shifted from phototrophy to chemotrophy these membranes disappear in an unknown fashion. In the present experiment, samples were taken for electron microscopy, cell density and bacteriochlorophyll determinations after shift from phototrophy to chemotrophy. The density of intracytoplasmic vesicles was measured on micrographs. During the first 2h growth is very slow and the ultrastructure remains unaltered. As growth resumes, the vesicles disappear at a rate which implies that they are not incorportated into the cytoplasmic membrane, nor actively digested, but remain intact and become increasingly diluted in the cytoplasm as the culture grows. The size of the vesicles was estimated to about 500 Å. The number of vesicles in phototrophically grown cells was calculated to about 575 per cell, and after 6h chemotrophic growth to about 100. The areas of the cytoplasmic and intracytoplasmic membranes are roughly calculated.
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    Sporogenesis in Streptomyces melanochromogenes (1978)
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    Archives of microbiology 118 (1978), S. 309-316 
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    ISSN: 1432-072X
    Keywords: Streptomyces melanochromogenes ; Sporogenesis ; Formation of sporulation septum ; Delimitation, separation, and release of spores ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mode of spore differentiation in a strain of Streptomyces melanochromogenes was followed by analysis of ultrathin sections of sporulating aerial hyphae at various stages of sporogenesis. A special accent was laid on the formation of the sporulation septum and its alterations in the course of spore delimitation and separation. Distinct differences in formation and substructure have been observed between the cross walls of vegetative hyphae and the sporulation septa. Cross walls of vegetative hyphae are formed in a way typical for Gram-positive bacteria by a centripetal annular ingrowth of cytoplasmic membrane, on which wall material immediately is deposited. The development of the sporulation septa is characterized by the accumulation of amorphous material in addition to the newly synthesized wall layer inside the invaginating cytoplasmic membrane. This amorphous septal material will later be decomposed presumably by two lytic systems which cause the separation of the spores. The central region of the finished sporulation septum is perforated by microplasmodesmata. Spores are released by a break down of the surface sheath. The complete spores are enveloped by a twolayered cell wall and the spiny surface sheath.
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    Capnocytophaga: New genus of Gram-negative gliding bacteria. II. Morphology and ultrastructure (1979)
    Springer
    Archives of microbiology 122 (1979), S. 17-27 
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    ISSN: 1432-072X
    Keywords: Gliding bacteria ; CO2-requiring ; Periodontal disease ; Gram-negative ; Ultrastructure ; Capnocytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gram-negative, anaerobic gliding bacteria were isolated from normal supragingival plaque and from periodontal lesions. Isolates could be divided into two size classes: small 2.4–4.2 μm×0.38–0.5 μm and large 4.8–5.8 μm×0.42–0.6 μm cells. The outer membrane was either loose-fitting and wavy, or taut, and of variable thickness. An electron-dense fuzz was discernible on several of the isolates. The periplasmic region was of variable electron-density. The genus Capnocytophaga has been proposed for these organisms based on morphological and cultural characteristics.
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    The ultrastructure and development of the colonial sheath of Microcystis marginata (1975)
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    Archives of microbiology 106 (1975), S. 209-214 
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    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Colonial sheath ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The colonial sheath of Microcystis marginata has a definite structure as seen by light and electron microscopy, consisting of a relatively smooth inner surface and densely packed, long fibrils on the outer surface. The sheath initially forms around the single cell and expands by continual deposition of sheath material to accomodate the synchronously dividing cells of the colony.
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    Growth of Nitrobacter in the presence of organic matter (1976)
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    Archives of microbiology 108 (1976), S. 305-312 
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    ISSN: 1432-072X
    Keywords: Nitrobacter agilis ; Chemoorganotrophic growth ; Acetate ; Formate ; Pyruvate ; Yeast extract-peptone ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. After a resting period of up to 6 months cells of Nitrobacter agilis grow with acetate, formate, and pyruvate as carbon and energy source. Yeast extract and peptone were added to supply the organism with nitrogen and to meet possible vitamin requirements. 2. The length of the growth period depends on the substrate; it increases according to the following sequence: pyruvate, formate, acetate. The highest growth yield is observed with pyruvate, the lowest with formate. 3. O2 consumption is increased in the presence of substrates as compared to endogenous respiration. With pyruvate and acetate twice as much O2 is consumed, with formate 7 times, with yeast extractpeptone 10 times as much. 4. The ability of nitrite oxidation is largely preserved, except in cells grown with acetate or pyruvate in the presence of 0.015% yeast extract and peptone. Such cells have nearly no cytochrome a 1. Accordingly, the cytochrome spectra of nitrite oxidizers grown under chemoorganotrophic and lithoautotrophic conditions coincide qualitatively. 5. The nitrite oxidizing system is inducible. It is induced by nitrite but also by substances present in yeast extract and peptone. Cells grown on acetate and yeast extract and peptone (0.015%) require 3–4 weeks before they regain the ability to grow with nitrite. Cells grown chemoorganotrophically with the same substrates and yeast extract and peptone (0.15%) start growing with nitrite as energy source without a lag. 6. Cell size and form, distribution of storage materials, order and fine structure of double membranes are correlated with growth conditions.
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    Synaptonemal complexes in antheridia of Achlya ambisexualis E87 (1977)
    Springer
    Archives of microbiology 112 (1977), S. 311-313 
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    ISSN: 1432-072X
    Keywords: Achlya ; Synaptonemal complexes ; Oömycetes ; Ultrastructure ; Gametangial meiosis ; Mycology ; Antheridium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first report of longitudinal sections of synaptonemal complexes in oömycetous fungi. These indicators of meiosis were observed in antheridial nuclei of Achlya ambisexualis E87. They were attached to a platelike structure at the inner membrane of the nuclear envelope. The lateral elements were separated from each other by an average distance of 160 nm. These results provide new ultrastructural evidence for gametangial meiosis in Oömycetes.
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    Ultrastructural study of microcyclic macroconidiation in Neurospora crassa (1978)
    Springer
    Archives of microbiology 116 (1978), S. 279-288 
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    ISSN: 1432-072X
    Keywords: Neurospora crassa ; Macroconidia ; Microcycle ; Heat ; Ultrastructure ; Nucleolus ; Proconidia ; Septa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heat-shock of macroconidia of Neurospora crassa at 46°C followed by shift-down to 25°C determines premature conidiogenesis. The nuclei and cytoplasm of heat-treated, swollen conidia contain spots of a dense material especially concentrated around the nucleolus in short time treated ones. In the first proconidium apically budding on the enlarged tip of the premature conidiophore, small vesicles are peripherally spread. A few such vesicles are later seen lining the initially simple septum separating the proconidial units into conidia. The doubling of this interconidial septum is surface viewn as a thick annulus. Disarticulation of the conidial units intervenes along a septal furrow of electroluscent material. Interconidial continuity through the septal pores is transiently insured by a connective which is ruptured for final liberation of the conidia.
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    Polyhedral inclusion bodies in cells of nitrosomonas spec (1977)
    Springer
    Archives of microbiology 112 (1977), S. 69-72 
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    ISSN: 1432-072X
    Keywords: Nitrosomonas spec ; Ammonia oxidizing bacterium ; Polyhedral inclusion bodies ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyhedral inclusion bodies were observed in cells of a Nitrosomonas species. They were present in growing cells as well as in resting cells. In thin sections their size was about 130 nm in growing cells and about 185 nm in diameter in resting cells. The bodies were commonly located in the nucleoplasm. They appeared to be bounded by a nonunit membrane and had a granular substructure. In thin sections about 70% of the exponentially grown cells and about 20% of the resting cells of the investigated strain showed 1–7 respectively 1–3 inclusion bodies.
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    Nutritional control of xanthine dehydrogenase. II. Effects on xanthine dehydrogenase and aldehyde oxidase of culturing wild-type and mutant Drosophila on different levels of molybdenum (1975)
    Springer
    Biochemical genetics 13 (1975), S. 53-64 
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    ISSN: 1573-4927
    Keywords: aldehyde oxidase ; xanthine dehydrogenase ; Drosophila melanogaster ; molybdenum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Two new mutants, deficient in aldehyde oxidase and xanthine dehydrogenase, have been isolated from a wild-type stock of Drosophila melanogaster and have been provisionally termed lxd c and lxd d, respectively, as both mutants appear to be allelic with lxd (low xanthine dehydrogenase). An analysis has been made of the effects of dietary molybdenum on lxd, lxd c, lxdd, lao (low aldehyde oxidase), mal (maroon-like eye color), and pac (Pacific) wild-type flies. On the lower dietary levels of 10 −3 M and 10 −2 M molybdenum, increases in specific activity of both enzymes were observed only in lxd. Furthermore, two- to three-fold increases in specific activity of both enzymes occurred in all strains, except mal, when cultured on 5×10 −2 M molybdenum. The lxd and lxd c strains failed to survive on this high concentration of the ion. Similar concentrations of molybdenum had no effect in vitro. An extra electrophoretic band of xanthine dehydrogenase was observed on polyacrylamide gel from extracts of wild-type flies cultured on certain levels of molybdenum, but its appearance was not always correlated with the increases in specific activity.
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    The size of poly(A)-containing RNAs in Drosophila melanogaster embryos (1976)
    Springer
    Biochemical genetics 14 (1976), S. 357-371 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; poly(A)-containing RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The size range of poly(A)-containing RNA from Drosophila melanogaster embryos has been estimated by hybridization with 3H-labeled poly(U) and subsequent fractionation on sucrose gradients. The median size of nuclear poly(A)-containing RNA is about 30 S (6000 nucleotides), and the median size of cytoplasmic poly(A)-containing RNA is about 17 S (1800 nucleotides). The relationship of these sizes to messenger RNA needed to code for protein and to the length of DNA contained in a chromomere is discussed.
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    Partial purification and properties of guanosine triphosphate cyclohydrolase from Drosophila melanogaster (1976)
    Springer
    Biochemical genetics 14 (1976), S. 259-270 
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    ISSN: 1573-4927
    Keywords: GTP cyclohydrolase ; Drosophila melanogaster ; pteridines ; dihydroneopterin triphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The first enzyme (named GTP cyclohydrolase) in the pathway for the biosynthesis of pteridines has been partially purified from extracts of late pupae and young adults of Drosophila melanogaster. This enzyme catalyzes the hydrolytic removal from GTP of carbon 8 as formate and the synthesis of 2-amino-4-hydroxy-6-(d-erythro-1′,2′,3′-trihydroxypropyl)-7,8-dihydropteridine triphosphate (dihydroneopterin triphosphate). Some of the properties of the enzyme are as follows: it functions optimally at pH 7.8 and at 42 C; activity is unaffected by KCl and NaCl, but divalent cations (Mg2+, Mn2+, Zn2+, and Ca2+) are inhibitory; the K m for GTP is 22 μm; and the molecular weight is estimated at 345,000 from gel filtration experiments. Of a number of nucleotides tested, only GDP and dGTP were used to any extent as substrate in place of GTP, and these respective compounds were used only 1.8% and 1.5% as well as GTP.
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    The suppressor of forked mutation in Drosophila melanogaster: Interactions with the lozenge gene (1976)
    Springer
    Biochemical genetics 14 (1976), S. 611-617 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; phenol oxidases ; spectrophotometry ; electrophoresis ; suppression ; ribosomal proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An interaction between the lozenge gene and the suppressor of forked gene of Drosophila melanogaster has been investigated both spectrophotometrically and electrophoretically. The nature of this interaction is such that certain lozenge alleles appear to be phenotypically suppressed while others are enhanced or unaffected, and the results reported demonstrate that the effect can clearly be observed at the biochemical level. Earlier observations have suggested that the suppressor of forked gene codes for a ribosomal protein, and this hypothesis is discussed.
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    Selection against homozygotes in the ADH polymorphic system of Drosophila melanogaster associated with the lethal factor l(2) Stm (1977)
    Springer
    Biochemical genetics 15 (1977), S. 93-100 
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    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase (ADH) ; genetic polymorphism ; selection ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In the natural populations +Tüb, +Prov, and +Rov, similar Adh F allele frequencies occur (q F=0.11, 0.18, and 0.08, respectively). However, there is a discrepancy in that the Adh F allele in +Tüb is closely linked to the lethal factor 1(2)Stm, which reduces relative fitness of the F phenotype to zero. In spite of this, polymorphism is maintained also in +Tüb, because the heterozygotes are superior to the homozygous S type (relative fitness=0.88). Under laboratory culture conditions, in +Tüb the relative fitness of the S genotype further decreases to 0.6. After outcrossing the lethal factor, relative fitnesses for S, FS, and F become 0.6, 1, and 0.48, respectively, implying that fitness for S remains the same. Relative values for S, FS, and F in +Prov, not affected by the lethal factor, are calculated by the maximum average fitness method to be 1, 1.2, and 0.2 under the assumption that heterozygous FS are similarly superior to S as in the natural +Tüb population and all allele frequencies found are stable equilibrium values.
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    Origin of α-glycerophosphate dehydrogenase isozymes in Drosophila melanogaster and their functional relationship in the α-glycerophosphate cycle (1977)
    Springer
    Biochemical genetics 15 (1977), S. 235-251 
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    ISSN: 1573-4927
    Keywords: l-glycerol-3-phosphate dehydrogenase (α-GPDH) ; isozymes ; development ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The basis for the differentiation of l-glycerol-3-phosphate dehydrogenase (α-GPDH) into larval and adult isozymes in Drosophila melanogaster was investigated by the correlation of a lack of appearance of each isozyme during development within Drosophila bearing α-GPDH “null” alleles and by the study of a putative conversion factor. Conversion studies indicate the presence of a heat-labile RNase-resistant conversion factor present in crude larval extracts with the ability to convert GPDH-1 to GPDH-2 and GPDH-3 but not vice versa. In addition, “null” mutations at the Gpdh locus obliterate all isozymatic species of α-GPDH in all developmental stages. These observations suggest that all α-GPDH isozymes are the product of a single structural gene and that the multiple forms of this enzyme arise during successive developmental stages through an epigenetic modification of the primary Gpdh + polypeptide. Finally, observations are reported which bear on the functional divergence of the α-glycerophosphate cycle in the adult and larval stage of development.
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    Isolation and genetic characterization of alcohol dehydrogenase thermostability variants occurring in natural populations of Drosophila melanogaster (1977)
    Springer
    Biochemical genetics 15 (1977), S. 971-988 
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    ISSN: 1573-4927
    Keywords: allozymes ; thermostability ; alcohol dehydrogenase ; Drosophila melanogaster ; natural populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Drosophila melanogaster collected from natural populations were examined fo thermostability variants within electrophoretic mobility classes of two enzymes. In alcohol dehydrogenase, two discrete forms of the “slow” allozyme and three discrete forms of the “fast” allozyme were revealed by postelectrophoretic treatments ranging from 15 sec at 40 C to 40 sec at 43 C. All variants have been mapped to within 0.7 unit of the Adh locus. Results of a geographic survey indicate that two alleles giving rise to fast-moderate and slow-moderate allozymes are common everywhere; other variants have a collective frequency ranging from 0% to 7%. In a test of the possibility that the rare Adh alleles could be generated by intragenic recombination between the two common alleles, electrophoresis and heat treatment of progeny recombinant for flanking markers of Adh revealed no new allozymes. Among 27 stocks containing slow α-glycerophosphate dehydrogenase allozymes and 109 fast stocks, heat treatments revealed no additional variation.
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    Control of drosopterin synthesis in Drosophila melanogaster: Mutants showing an altered pattern of GTP cyclohydrolase activity during development (1978)
    Springer
    Biochemical genetics 16 (1978), S. 13-26 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; GTP cyclohydrolase ; development ; pteridine biosynthesis ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The reaction catalyzed by GTP cyclohydrolase is the first unique step of pteridine biosynthesis in Drosophila melanogaster and is therefore likely to be an important control point. GTP cyclohydrolase activity varies during development, showing two distinct peaks of activity—one at pupariation and a much larger peak at emergence. Most of the early pupal enzyme is located in the body region, whereas in late pupal and early adult life most of the activity is found in the head. Mixing experiments indicate that developmental changes in activity are not due to changes in the level of a direct effector of GTP cyclohydrolase. The mutants raspberry and prune show an increased GTP cyclohydrolase activity at pupariation relative to wild type, but a decreased enzyme activity at emergence. The changes in GTP cyclohydrolase activity are reflected in changes in pteridine levels in these mutants. Several lines of evidence suggest that neither locus is the structural gene for GTP cyclohydrolase. The raspberry and prune gene products may play a specific role in regulating GTP cyclohydrolase activity during development.
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    A genetic and developmental analysis of an acid deoxyribonuclease in Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 1113-1134 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; isozymes ; position effect ; segmental aneuploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A deoxyribonuclease, called DNase-1, that is active at acid pH in the presence of EDTA has been studied in Drosophila melanogaster. The locus for the enzyme maps genetically to 61.8 on the right arm of the third chromosome. Cytogenetically, DNase-1 has been localized to within five to ten bands between 90C-2 and 90E. This analysis utilizes both electrophoretic variants and the Y-autosome translocations of Lindsley et al. (1972). DNase-1 is present in all stages of the life cycle, and the paternal genome actively contributes DNase-1 to the embryo between 0 and 1 hr after fertilization.
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    Variation in amount of enzyme protein in natural populations (1978)
    Springer
    Biochemical genetics 16 (1978), S. 159-170 
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    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; allozyme properties and amounts ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Among strains of Drosophila melanogaster each derived from a single fertilized female taken from natural populations, there is variation in both alcohol dehydrogenase (ADH) activity and the amount of ADH protein. The correlation between ADH activity and number of molecules over all strains examined is 0.87 or 0.96 in late third instar larvae depending on whether the substrate is 2-propanol or ethanol. With respect to the two common electrophoretic allozymic forms, F and S, segregating in these populations, the FF strains on the whole have higher ADH activities and numbers of ADH molecules than the SS strains. Over all strains examined, enzyme extracts from FF strains have a mean catalytic efficiency per enzyme molecule higher than that of enzyme extracts from SS strains when ethanol is the substrate, and much higher when 2-propanol is the substrate. One FF strain had an ADH activity/ADH protein ratio characteristic of SS strains.
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    Alcohol metabolism in Drosophila melanogaster: Uselessness of the most active aldehyde oxidase produced by the Aldox locus (1978)
    Springer
    Biochemical genetics 16 (1978), S. 203-211 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; alcohol tolerance ; alcohol utilization ; alcohol dehydrogenase ; aldehyde oxidase ; allozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Alcohol dehydrogenase is necessary for ethanol detoxification and metabolic utilization. It has been generally assumed that aldehyde oxidase (AO) produced by the Aldox locus (3–56.7) is necessary for a further transformation of acetaldehyde into acetate. We find that various mutant strains (ma-l or Aldox n) which do not produce an active enzyme show about the same tolerance to alcohol as do wild strains. This physiological paradox is probably to be explained by the discovery of another locus (not localized) which produced a small amount of AO in all tested strains. The adaptive significance of the genetically polymorphic Aldox locus is probably to be looked for in physiological pathways other than ethanol metabolism.
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    A simple approach for discovering common nonelectrophoretic enzyme variability: A heat denaturation study in Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 299-305 
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    ISSN: 1573-4927
    Keywords: nonelectrophoretic structural variability ; Drosophila melanogaster ; phosphoglucomutase ; genetic polymorphism ; heat denaturation study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A simple procedure is described to detect genetic heterogeneity within electrophoretic classes at a locus in Drosophila, based on electrophoresis and heat denaturation studies. Temperature-resistant (tr) and temperature-sensitive (ts) isoelectrophoretic alleles at the phosphoglucomutase locus (Pgm) are present at polymorphic frequencies in natural and in laboratory populations of Drosophila melanogaster.
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    Developmental changes of sepiapterin synthase activity associated with a variegated purple gene in Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 197-206 
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    ISSN: 1573-4927
    Keywords: sepiapterin synthase ; variegation ; purple ; Drosophila melanogaster ; pteridine eye pigments ; drosopterin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A variegated position effect on the autonomous gene, purple, has been studied enzymologically in Drosophila melanogaster. Sepiapterin synthase, the enzyme system associated with pr +, was examined for activity in different developmental stages of the fly. The results indicate that T(Y:2) pr c5, cn/prc4 cn flies (flies in which pr + has been translocated and which exhibit variegation) have a reduced amount of enzyme activity as compared with both Oregon-R and pr 1 flies. This reduction in activity was not found in larval stages, which suggests that the inactivation process probably occurs in late larval or early pupal stages. The phenotype of the variegated adult has white eyes with red-colored spots and patches where drosopterins occur. The phenotype of the fly carrying the translocation is modified by the presence of additional Y chromosomes. This extends the observation from other systems that extra heterochromatin acts to suppress the variegated position effect. The advantages of studying the variegation by measuring enzyme activity, as well as the phenotypic expression, are several; for example, the developmental time at which variegation occurs may be estimated even though drosopterin synthesis is not occurring.
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    Polymorphism at the G6pd and 6Pgd loci in Drosophila melanogaster. III. Developmental and biochemical aspects (1979)
    Springer
    Biochemical genetics 17 (1979), S. 1131-1144 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; enzyme polymorphism ; G6PD ; 6PGD ; enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The electrophoretic variants of G6PD and 6PGD isolated from the Bogota Drosophila melanogaster population were characterized developmentally and biochemically. Changes in in vitro enzyme activity during development were comparable to those found for other dehydrogenases: an increase in the larval and adult stage and a decrease in the pupal stage. During the whole life cycle the “S” enzyme of both loci showed a higher activity than the “F” enzyme. MgCl2 had a stimulating effect on the activity of both enzymes whereas their heat stability was decreased. The allozymes of 6PGD had different Vmax's but were comparable with respect to Km values, pH optimum, and stability at 45 C. the allozymes of G6PD showed different Vmax's and differed in stability at 35 C, but had similar Km values and pH optima. As the difference in stability was probably due to differences in molecular structure of the allozymes, the differences in activity found at high pH and high MgCl2 concentration were most probably due to this difference in stability.
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    Transport defects as the physiological basis for eye color mutants of Drosophila melanogaster (1975)
    Springer
    Biochemical genetics 13 (1975), S. 603-613 
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    ISSN: 1573-4927
    Keywords: transport mutants ; eye color mutants ; kynurenine ; Drosophila melanogaster ; Malpighian tubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Kynurenine-H 3 transport and conversion to 3-hydroxykynurenine were studied in organ culture using the Malpighian tubules and developing eyes from wild type and the eye color mutants w, st, 1td, ca, and cn of Drosophila melanogaster. Malpighian tubules from wild type have the ability to concentrate kynurenine and convert it to 3-hydroxykynurenine. The tubules from w, st, 1td, and ca are deficient in the ability to transport kynurenine, as are the eyes of the mutants w, st, and 1td. This defect in kynurenine transport provides a physiological explanation for the phenotypic properties of the mutants. The relationship of these measurements to previous observations on these eye color mutants is discussed and the transport defect hypothesis is consistently supported. We have concluded that several of the eye color mutants in Drosophila are transport mutants.
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    Correlation of guanosine triphosphate cyclohydrolase activity and the synthesis of pterins in Drosophila melanogaster (1976)
    Springer
    Biochemical genetics 14 (1976), S. 271-280 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; GTP cyclohydrolase ; pteridine biosynthesis ; development ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The enzyme guanosine triphosphate cyclohydrolase (GTP cyclohydrolase), which in bacteria is known to be the first enzyme in the biosynthetic pathway for the synthesis of pteridines, has been discovered in extracts of Drosophila melanogaster. Most of the enzyme (80%) is located in the head of the adult fly. An analysis of enzyme activity during development in Drosophila has revealed the presence of a relatively small peak of activity at pupariation and a much larger peak that appears at about the time of eclosion. Enzyme activity declines rapidly as the fly ages. Analyses for the production of the typical pteridine pigments of Drosophila have indicated that the small peak of GTP cyclohydrolase activity evident at pupariation coincides with the appearance of isoxanthopterin, sepiapterin, and pterin, and the larger peak at eclosion roughly corresponds to the accumulation of drosopterin as well as to the appearance in larger amounts of pterin and sepiapterin. These observations strongly suggest that in Drosophila, like bacteria, GTP cyclohydrolase is involved in the biosynthesis of pteridines. Analyses of a variety of zeste mutants of Drosophila melanogaster have shown that these mutants all contain GTP cyclohydrolase equal approximately to the amount found in the wild-type fly. These observations do not support the suggestions made by Rasmusson et al. (1973) that zeste is the structural locus for GTP cyclohydrolase.
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    Genetics and physiological expression of β-hydroxy acid dehydrogenase in Drosophila (1978)
    Springer
    Biochemical genetics 16 (1978), S. 333-342 
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    ISSN: 1573-4927
    Keywords: β-hydroxy acid dehydrogenase ; chromosome ; dosage compensation ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A mutant Had nl was induced in Drosophila melanogaster and found to be deficient in β-hydroxy acid dehydrogenase. This mutation was utilized to study the genetics and physiological expression of Had +. Had+ was mapped to the X chromosome at 54.4 and seems to be the structural gene for the enzyme. Enzyme activity in male and female flies indicates that the gene shows both dosage compensation independent from dose effect and differential activity during ontogeny. Electrophoretic mobility data indicate that the enzyme is a dimer which forms by random association of subunits. The fact that the mutant shows no detrimental effect implies that the enzyme is dispensable, at least under laboratory conditions. The biological and technical implications of this gene-enzyme system are discussed.
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    Dietary rescue of a lethal “null” activity allele of 6-phosphogluconate dehydrogenase in Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 469-475 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; 6-phosphogluconate dehydrogenase ; Pgd n lethal alleles ; rescue by dietary supplements ; hexose monophosphate shunt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The genetic rescue of Pgd n lethal alleles, accomplished by combining them with mutations lacking glucose-6-phosphate dehydrogenase activity, has led to the hypothesis that Pgd n lethality may be due to the accumulation of 6-phosphogluconate. In this article we report the rescue of Pgd n /Y males by dietary supplements (fructose and linolenate) designed to minimize 6-phosphogluconate production.
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    Biochemical properties of esterase 6 in Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 1-22 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; esterase 6 ; allozymes ; biochemical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Biochemical properties of esterase 6 in Drosophila melanogaster were investigated using partially purified preparations from three genotypes, 1/1, 1/2, and 2/2. The molecular weight of the enzyme is estimated to be about 90,000, and treatment with sodium dodecylsulfate cleaves the enzyme into four units with a molecular weight of about 22,000. The activity toward 28 naturally occurring esters was assayed and shown to vary considerably with substrate, the 1/1 preparation having in general higher activity than 1/2 and 2/2, which were very similar. Heat sensitivity, the effect of metal ions, and the effects of the presence or absence of an end product were also studied. The differences demonstrated between allozymes would allow considerable scope, under appropriate conditions, for differential selection to operate between genotypes.
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    Properties of the two common electrophoretic variants of phosphoglucomutase in Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 825-836 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; phosphoglucomutase ; polymorphism ; enzyme kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phosphoglucomutase (PGM) of adult stage in Drosophila melanogaster has been characterized by gel filtration, ion-exchange chromatography, and isoelectric focusing. The two common electrophoretic variants, PGMA and PGMB, differ with respect to their kinetic and stability parameters. PGMA is more thermostable than PGMB but shows the same pH optimum, equal dependence on Mg2+, and identical molecular weight. There is no significant kinetic difference between the two allozymes at the optimum pH value, but at pH 6.0 the K m value for glucose-1,6-diphosphate of PGMB is significantly higher than that of PGMA. This difference might explain the observed selective advantage of the Pgm A allele in population studies.
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    Biological role of alcohol dehydrogenase in the tolerance of Drosophila melanogaster to aliphatic alcohols: Utilization of an ADH-null mutant (1976)
    Springer
    Biochemical genetics 14 (1976), S. 989-997 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; alcohol dehydrogenase ; enzyme biological activity ; toxicity of alcohols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The toxicity of the first eight primary alcohols and of four secondary alcohols was compared in a wild-type strain (having active ADH) and an ADH-negative mutant. Differences between lc 50 measured in the two strains allowed an evaluation of the biological activity of the enzyme. In vitro, ADH is mainly active on secondary alcohols, while in vivo its main role is the detoxification and metabolism of ethanol. These observations suggest that originally ADH was involved in unknown metabolic pathways and that its utilization in ethanol metabolism could be a recent event.
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    Preparation of specific antisera to Drosophila acid phosphatase without rigorous protein purification (1976)
    Springer
    Biochemical genetics 14 (1976), S. 237-243 
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    ISSN: 1573-4927
    Keywords: null alleles ; antibody purification ; Drosophila melanogaster ; immunological methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Extracts from an acid phosphatase CRM− null mutant of Drosophila melanogaster were used to eliminate contaminating antibodies in a nonspecific preparation of anti-acid phosphatase serum. This method of producing specific antisera makes unnecessary the rigorous purification of an antigen prior to immunization attempts in those cases where CRM− null mutants of the antigen are available. Antisera so prepared could be used for a wide variety of purposes.
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    Association and the Adh locus with a lethal factor (l(2) Stm) in Drosophila melanogaster (1976)
    Springer
    Biochemical genetics 14 (1976), S. 299-308 
    Details
    ISSN: 1573-4927
    Keywords: allozymes ; alcohol dehydrogenase ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Keeping Drosophila cultures at 28 C results in elimination of all minor multiple ADH bands, thought to be due to conformational change. Thus in diploid and triploid adults heterozygous for the Adh F and Adh Salleles, relative staining intensities are found for the three bands which were in conformity with the assumption that both alleles are equally expressed. Among all polymorphic strains derived from natural Central European and Mediterranean populations, the strain +Tüb is unique in that its Adh Fallele is closely linked to a new recessive lethal factor, named 1(2)Stm. All Adh F 1/AdhF 1 pupae are unable to emerge, and die. The lethal effect is obvious 50 hr earlier by retarded eye, bristle, and body wall pigmentation. Although all pupae of the phenotype F die, Adh F allele frequency scarcely seems to be lowered in this natural population.
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    Further evidence of thermostability variation within electrophoretic mobility classes of enzymes (1976)
    Springer
    Biochemical genetics 14 (1976), S. 383-387 
    Details
    ISSN: 1573-4927
    Keywords: allozymes ; thermostability ; alcohol dehydrogenase ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Two Drosophila melanogaster strains, each heterozygous for “fast” and “slow” alleles at the Adh locus, and each having balanced second chromosomes, were found to differ in the apparent thermostability of the slow allozyme. The two strains were crossed, and F1heterozygotes were separated on the basis of the origin of the slow allele. After electrophoresis, the cellulose acetate strips were treated 1 1/2 min at 35 C. The putatively more sensitive allozyme showed a strikingly greater response to heat. These findings further support the conclusion that electrophoretically cryptic allelic differences exist which are expressed in thermostability differences. Further application of this approach has revealed one similar sensitive slow allozyme and three cases of a relatively resistant fast ADH allozyme in wild-caught flies.
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    Demonstration of 6-phosphogluconolactonase activity in Drosophila melanogaster using a null allele of 6-phosphogluconate dehydrogenase (1978)
    Springer
    Biochemical genetics 16 (1978), S. 1023-1029 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; 6-phosphogluconolactonase ; hexose monophosphate shunt ; Pgd n Zw n mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Using a double mutant strain, Pgd n Zw n , we have developed an assay for 6-phosphogluconolactonase activity and have demonstrated its occurrence in adult Drosophila melanogaster.
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    Enumeration of Drosophila form II DNA-dependent RNA polymerase initiation sites on Drosophila DNA (1979)
    Springer
    Biochemical genetics 17 (1979), S. 97-104 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; form II RNA polymerase initiation sites ; chromomeres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The in vitro incorporation of γ-32P-labeled nucleoside triphosphates into RNA by Drosophila melanogaster form II RNA polymerase from template sites which afford protection from the initiation inhibitor, polyriboinosinic acid (poly [I]), is used as a method for enumerating a specific class of transcription initiation sites on D. melanogaster DNA. Such sites number about 4000 per haploid genome for D. melanogaster. This value is in good agreement with the number of functional genetic units in the D. melanogaster genome as determined by classical cytogenetics.
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    Purine transport by Malpighian tubules of pteridine-deficient eye color mutants of Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 565-573 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; Malpighian tubules ; purine transport ; eye color mutants ; riboflavin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Uptakes of guanine into Malpighian tubules of wild-type Drosophila and the eye color mutants white (w), brown (bw), and pink-peach (p p) have been compared. Tubules for each of these mutants are unable to concentrate guanine intracellularly. The transport of xanthine and riboflavin is also deficient in w tubules. The transport of guanosine, adenine, hypoxanthine, and guanosine monophosphate is similar in wild-type and white Malpighian tubules. These data and other information about these mutants make it likely that these pteridine-deficient eye color mutants do not produce pigments because of the inability to transport a pteridine precursor. This view supports the hypothesis that mutants which lack both pteridine and ommochromes do so because precursors to both classes of pigments share a common transport system.
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  • 84
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    Variants of α-glycerophosphate dehydrogenase in diploids and triploids of Drosophila melanogaster (1975)
    Springer
    Biochemical genetics 13 (1975), S. 263-271 
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    ISSN: 1573-4927
    Keywords: allozymes ; α-glycerophosphate dehydrogenase ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract On the basis of band staining intensities in electrophoretic runs of single flies homozygous and heterozygous for two alleles at the autosomal locus for GPDH, F allele activity is believed to be 8% lower than S allele activity. Indeed, the intensity distribution in the patterns of FSS and FFS triploid females shows that both are not equally expressed. On a per fly or live weight basis, females with two and three doses of the Gpdh gene show bands with equal staining intensity, thus exhibiting a dosage effect when GPDH activity is estimated on a per cell basis.
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    Variation between electrophoretically identical alleles at the alcohol dehydrogenase locus in Drosophila melanogaster (1975)
    Springer
    Biochemical genetics 13 (1975), S. 721-731 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; enzyme variation ; alcohol dehydrogenase ; electrophoretically identical alleles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A new variant of alcohol dehydrogenase (ADH 71k) was found in a laboratory stock of Drosophila melanogaster. ADH in this stock had the same electrophoretic mobility as the F variant both on acrylamide and on agar. Activity levels were similar to the levels in F flies at temperatures between 15 and 25 C. But while ADH F enzyme is inactivated rapidly at 40 C, ADH 71k is still active. Also, ADH S is not inactivated at this temperature, but has a far lower activity per fly than ADH 71k. Genetic analysis showed that the new variant is an allele of the Adh locus.
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    Isozyme variability in species of the genus Drosophila. VIII. The alcohol dehydrogenase polymorphism in north carolina populations of D. melanogaster (1976)
    Springer
    Biochemical genetics 14 (1976), S. 47-58 
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    ISSN: 1573-4927
    Keywords: electrophoresis ; alcohol dehydrogenase ; Drosophila melanogaster ; isozymes ; genetic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Adult Drosophila melanogaster flies collected from populations broadly dispersed over ecological and geographic strata of North Carolina, and over a period of 4 years, were analyzed for alcohol dehydrogenase phenotypes by gel electrophoresis. Gene frequencies in spring-summer-fall field collections were remarkably stable over all strata. Two winter collections exhibited contrasting gene frequency changes. In one case the results are interpreted in terms of long-distance migration from Florida, while the other is explicable by assignment of a causal role to environmental factors which accompany the winter season.
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    Heat stability studies at the α-glycerophosphate dehydrogenase locus in populations of Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 769-775 
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    ISSN: 1573-4927
    Keywords: hidden variation ; α-GPDH ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The level of hidden variation in populations of Drosophila melanogaster at the Gpdh + locus was determined by thermal stability studies of the protein. The results indicate a lack of variation using these methods both in and between the two common electrophoretic variants. It is suggested that α-GPDH is conserved in primary structure, which may be related to its critical role in flight muscle metabolism.
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    Mutagenesis at the cinnabar locus in Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 855-865 
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    ISSN: 1573-4927
    Keywords: kynurenine hydroxylase ; cinnabar locus ; EMS mutagenesis ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A study was undertaken to isolate mutations affecting the temporal appearance of kynurenine hydroxylase in Drosophila melanogaster. Such mutations, lacking or having reduced enzyme activity at the larval or pupal stage only, could represent changes in regulatory functions. Mutagenesis was carried out using EMS. Potential mutations were isolated from mass F1 cultures. The screening of large numbers of individuals was made possible by the use of the mutant red, which allowed visual classification for the presence or absence of the enzyme at both stages. From a series of six mutagenesis experiments 111,561 chromosomes were tested, and 122 phenotypically mutant F1 individuals were found. From these, 38 inheritable mutations were isolated which, by phenotypic observation, lacked or had reduced enzyme activity at the larval and pupal stages. Assay of enzyme activity levels in several of the mutants confirmed the phenotypic data. All of the 27 mutations that could be tested further are recessive and behave as cinnabar alleles. Complementation tests were performed between these 27 mutant stocks, and no complementation in the production of eye color has been seen between the mutants examined. When extended collection periods were used, a significantly higher percentage of inheritable mutations was isolated from the first 3 days of the screen. Over 80% of the F1 phenotypic mutants could be classified as mosaics, which indicates that cinnabar can be autonomous under certain conditions. The failure to isolate mutations in possible regulatory function is discussed.
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    Isolation and biochemical analysis of a temperature-sensitive scarlet eye color mutant of Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 149-158 
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    ISSN: 1573-4927
    Keywords: xanthommatin synthesis ; scarlet mutants ; Drosophila melanogaster ; temperature-sensitive mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Six new EMS-induced scarlet mutants were selected. Four of these were partially pigmented, with xanthommatin levels ranging from 12% to 45% of normal. In one (st 754ts), pigment production was temperature sensitive; the level of xanthommatin changed from less than 10% of normal at 29 C to more than 70% at 18 C. In all of the new mutants tested, the level of early pupal 3-hydroxykynurenine was as low as low as that in st 1. Thus reduced larval accumulation of this metabolite also appears to be a characteristic feature of scarlet mutants. Temperature-pulse and temperature-shift experiments were carried out with st 754ts to determine the temperature-sensitive period for the scarlet gene during development. The major sensitive period commenced prior to the onset of pigmentation and was over before adult emergence. Thus the initiation of xanthommatin synthesis is not brought about by the activation of the scarlet gene. In similar experiments carried out with a temperature-sensitive white mutant (w bl), a similar temperature-sensitive period was obtained.
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    Partial purification and some properties of biopterin synthase and dihydropterin oxidase from Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 351-369 
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    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; biopterin synthesis ; oxidation of dihydropterins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An enzyme which has been named “biopterin synthase” has been discovered in Drosophila melanogaster. This enzyme, which has been purified 200-fold from extracts of Drosophila, catalyzes the conversion of sepiapterin to dihydrobiopterin, or oxidized sepiapterin to biopterin. The K m values for the two substrates are 63 µm for sepiapterin and 10 µm for oxidized sepiapterin. NADPH is required in this enzymatic reaction. An analysis of enzyme activity during development in Drosophila indicates a correlation between enzyme activity and biopterin content at various development stages. Another enzyme, called “dihydropterin oxidase,” was also discovered and partially purified. This enzyme catalyzes the oxidation of dihydropterin compounds to the corresponding pterin compounds. For example, sepiapterin (a dihydropterin) is oxidized to oxidized sepiapterin in the presence of this enzyme. The only dihydropterin that has been tested that is not a substrate for this enzyme is dihydroneopterin triphosphate, the compound thought to be a precursor for all naturally occurring pterins and dihydropterins. Since the action of dihydropterin oxidase is reduced significantly when the concentration of oxygen is very low, it is likely that this enzyme uses molecular oxygen as the oxidizing agent during the oxidation of dihydropterins. Neither NAD+ or NADP+ is required. In the presence of the two enzymes dihydropterin oxidase and biopterin synthase, sepiapterin is converted to biopterin. However, in the presence of biopterin synthase alone, sepiapterin is converted to dihydrobiopterin.
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    Morphological aspects of the galactomannan formation in the endosperm ofTrigonella foenum-graecum L. (Leguminosae) (1977)
    Springer
    Planta 133 (1977), S. 243-248 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm ; Galactomannan ; Secretion ; Ultrastructure ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mode of deposition (secretion) of galactomannan in the cells of the seed endosperm ofTrigonella foenum-graecum has been studied by electron microscopy. In cells which are just beginning to secrete galactomannan there are stacks of rough endoplasmic reticulum (ER). The intracisternal space (containing the enchylema) of the rough ER then swells, becomes vacuolated and forms a voluminous network, with “pockets” of cytoplasm entrapped within poculiform rough ER. The enchylema contains material which reacts with periodate-thiocarbohydrazidesilver proteinate in a very similar manner to the galactomannan already deposited in the cell wall. It appears that the galactomannan is formed in the intracisternal space of the rough endoplasmic reticulum and then expelled outside the plasmalemma. This mode of deposition contrasts with that of other plant cell wall polysaccharides whose secretion is mediated by Golgi vesicles.
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    Structural and functional analysis of the scute locus in Drosophila melanogaster (1979)
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    Theoretical and applied genetics 55 (1979), S. 231-238 
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    ISSN: 1432-2242
    Keywords: Drosophila melanogaster ; Scute locus ; Maps ; Operon-like model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The functional expression of 12 scute alleles in homozygotes and compounds of Drosophila melanogaster at 14°, 22°, 30°C is analysed. Based on the data obtained, linear maps for bristles and mutations are built. The basic features of the maps, clustering and polarity, are invariable with respect to temperature, scute gene dosage and cross direction. In addition local dominance of the norm over bristle reduction was produced by the scute mutation; different types of complementation reactions were established for each bristle. The gene scute is treated as an operon-like system, composed of 3–4 cistrons with each controlling the formation of bristles on a particular region of the fly's body. This model argues well with the structure of maps constructed and implies a post-translational level of initial events of bristle-formation process.
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    The ultrastructure of the sinus gland of Gammarus oceanicus (Crustacea: Amphipoda) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 557-564 
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    ISSN: 1432-0878
    Keywords: Sinus gland ; Gammarus ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sinus gland of Gammarus oceanicus, like that of other crustaceans, is composed of three elements: neurosecretory axons, glial cells and stromal sheath. Five neurosecretory axon types are identified on the basis of granule diameter, shape, and electron density, and axon matrix density. Exocytosis appears to be the major release mechanism of neurosecretory material. The preterminal regions of neurosecretory axons contain axoplasmic reticulum and neurotubules. Their arrangement in the axon and relationship with one another suggest a transport function. Multilamellar bodies are found in the terminal regions of neurosecretory axons. They arise from mitochondria and may be involved in granulolysis.
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    Biosynthesis of the basal lamina as a result of interaction between thyroid and mesenchymal cells in culture (1979)
    Springer
    Cell & tissue research 200 (1979), S. 69-81 
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    ISSN: 1432-0878
    Keywords: Thyroid follicular cells ; Basal lamina, biosynthesis ; Cellular interaction ; Cell culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Porcine thyroid cells were cultured alone or in mixed cultures with mesenchymal cells. The formation of a basal lamina in vitro was investigated ultrastructurally. Follicular reassociation of thyroid cells occurred in both types of culture; however, it was followed by formation of the basal lamina only when mesenchymal cells were present. The present findings suggest an epithelial origin of the basal lamina resulting from an interaction with mesenchymal cells.
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    Ultrastructural identification of non-adrenergic, non-cholinergic nerves in the rat anococcygeus muscle (1979)
    Springer
    Cell & tissue research 200 (1979), S. 257-271 
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    ISSN: 1432-0878
    Keywords: Anococcygeus muscle ; Innervation ; P-type nerves ; Purinergic nerves ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the rat anococcygeus muscle has been investigated ultrastructurally following fixation with a modified chromaffin reaction for the demonstration of biogenic amines (Tranzer and Richards, 1976). Three types of nerve profiles were revealed: (1) 60–70 % of the profiles are adrenergic; (2) less than 5% of the profiles appear to be cholinergic; (3) up to 40% of the profiles are distinguished by the presence of a characteristically high proportion of electron-opaque, chromaffin-negative vesicles, 85–110nm in diameter. This third type of profile was not affected by 6-OHDA, and is considered to represent the non-adrenergic, non-cholinergic inhibitory innervation of this tissue. Because of the morphological similarity of this nerve type, apart from the smaller vesicle size, to classical peptidergic nerve endings, they have been termed “small p-type” (sp-type). These results are discussed in relation to a previous report describing only two types of nerve profiles in this tissue (Gillespie and Lüllmann-Rauch, 1974).
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    A stereological ultrastructural study of stimulated peritoneal macrophages in the germ-free mouse (1979)
    Springer
    Cell & tissue research 200 (1979), S. 299-309 
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    ISSN: 1432-0878
    Keywords: Germ-free mice ; Inflammation ; Macrophages ; Peritoneum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Peritoneal macrophage ultrastructure was analysed stereologically in germ-free mice given a single intraperitoneal injection of sterile, pyrogen-free saline. Thus the stimulant was non-particulate, non-antigenic and inorganic, and effects of immune reactions were minimal. Macrophages were recovered 1, 6, 24 and 72 h after stimulation. A sequence of structural alterations is reported which may be fundamental to macrophage activation. The plasma membrane and nuclear envelope increased in area within only 1 h of saline injection. During the next 5 h loss of plasma membrane, probably by pinocytosis, caused cellular “rounding” and clear-cut alteration in surface configuration. At the same time lysosome-like granules enlarged but decreased in number. By 24 h most cellular structures and compartments (including the plasma membrane) were enlarged. Morphological evidence of nuclear activation accompanied a rather modest enlargement of the nucleus at this stage. The RER hypertrophied last and must, therefore, be judged sufficient in resident macrophages to support the initial growth response which results after stimulation. Thus hypertrophy was observed eventually in every structure examined. Even the minimally activated macrophages resident in the peritoneum of germ-free mice respond readily to stimulation.
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    An ultrastructural analysis of the gametes and early fertilization in two bivalve molluscs, Chama macerophylla and Spisula solidissima with special reference to gamete binding (1977)
    Springer
    Cell & tissue research 182 (1977), S. 469-489 
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    ISSN: 1432-0878
    Keywords: Fertilization ; Molluscs ; Spermatozoon ; Oocyte ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural investigation of the gametes and their interaction during the early events of fertilization in molluscs has been performed. A gamete binding event involving large numbers of sperm has been identified and examined in detail. The surface of the oocyte is projected into numerous microvilli which extend through the vitelline envelope. Tufts of fibrillar material radiate from the tips of these microvilli, forming a layer external to the vitelline envelope. The acrosomal vesicle of the mature spermatozoon contains two major components, which function differently during fertilization. The vesicle is indented at its adnuclear surface, constituting a preformed acrosomal tubule. This tubule does not elongate during the acrosome reaction. Completion of the reaction results in the formation of an extracellular coat, derived from one component of the acrosomal vesicle, on the anterior surface of the sperm. Sperm-egg binding is accomplished by an association of the extracellular coat on the reacted sperm and the fibrous tufts on the tips of the microvilli of the oocyte. Evidence that gamete membrane fusion occurs by fusion of the acrosomal tubule and a microvillus is presented. These observations provide a generalized pattern of molluscan fertilization.
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    The role of the haemocytes of Clitumnus extradentatus in haemolymph coagulation (1977)
    Springer
    Cell & tissue research 182 (1977), S. 513-524 
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    ISSN: 1432-0878
    Keywords: Haemocytes ; Insects ; Haemolymph coagulation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron-microscopic observations of the blood cells (haemocytes) of the stick insect Clitumnus extradentatus in vitro showed that two morphologically distinct cell types, the cystocytes and granular cells are involved in haemolymph coagulation. Both these cell types contain a variable number of electron-dense granules which upon release cause progressive coagulation and precipitation of the haemolymph. In the cystocytes this release is extremely rapid (30–60s) while in the granular cells it only occurs after 1–2min in vitro. The role of these cells in haemostasis is discussed together with the possible significance of the involvement of two cell types in the coagulation process.
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    Ultrastructural tracer studies on the permeability of the Malpighian tubule of the Pill Millipede, Glomeris marginata (Villers) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 549-556 
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    ISSN: 1432-0878
    Keywords: Malpighian tubules ; Millipede ; Ultrastructure ; Tracers ; Formed bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The electron-dense tracers ferritin, and iron-dextran, and the protein horseradish peroxidase, have been used to investigate the ultrastructural basis of permeability in the upper and lower segments of the Malpighian tubules of Glomeris marginata. All these materials were able to cross the basal lamina and enter the tubule lumen of the upper segment, and it was established that horseradish peroxidase was able to enter the channels which interrupt the apical junctions. In the upper segment, ferritin, iron-dextran, and horseradish peroxidase are all taken up and accumulated within intracellular vesicles. In the lower segment ferritin and iron-dextran enter the cells but become generally distributed over the cyptoplasm, as well as entering membrane-bounded vacuoles. The behaviour of horseradish peroxidase could not be assessed owing to the presence of endogenous peroxidase activity in the cells. After fixation by direct application of glutaraldehyde to the undissected tubules, the extracellular spaces contained large numbers of membrane-bounded vesicles. The significance of these observations is discussed in relation to the physiological activities of the tubules.
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    The surface of the pecten oculi in the pigeon (1975)
    Springer
    Cell & tissue research 157 (1975), S. 457-465 
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    ISSN: 1432-0878
    Keywords: Pecten oculi ; Pigeon ; Surface ; Function ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A scanning electron microscopic study of the pecten reveals the rib-like character of the pectinal folds, the nature of their connections with the base and bridge of the pecten as well as the presence of interconnections between the bundles of superficial collagenous fibres. It has been suggested that the pecten may have a mechanical significance, namely protection of the retina from the excessive movements of the vitreous humour. The relationship between the superficial membrane of the folds which is continuous, the intercellular spaces and the process of diffussion has also been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222599
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