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  • Electron microscopy  (378)
  • Scanning electron microscopy  (77)
  • Drosophila melanogaster  (67)
  • Springer  (522)
  • Periodicals Archive Online (PAO)
  • 1975-1979  (522)
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Keywords
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Year
  • 1
    Electronic Resource
    Electronic Resource
    The morphology of bone mineral crystals (1978)
    Springer
    Calcified tissue international 25 (1978), S. 217-222 
    Details
    ISSN: 1432-0827
    Keywords: Bone mineral ; Electron microscopy ; X-ray diffraction ; Dark field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Electron microscopical observations of the size and shape of bone mineral crystallites have not been in complete agreement with X-ray diffraction findings. The two prevalent viewpoints consider bone mineral crystals to be either rod, or plate like in habit. There appears to be agreement that the smallest dimension of the crystals is about 5 nm, but there is discrepancy in the reported c-axial lengths. The method of dark field imaging is used to obtain a quantitative measurement of the c-axial length distribution in rabbit, ox and human bone: mean c-axial lengths 32.6 nm, 36.2 nm and 32.4 nm, respectively, show no significant difference at the 5% level to the mean c-axial length measured by X-ray line broadening. Both bright and dark field images strongly suggest that bone mineral has a plate like form. Reasons for past discrepancies are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010772
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  • 2
    Electronic Resource
    Electronic Resource
    Time-related changes in the ultrastructure of osteoclasts after injection of parathyroid hormone in young rats (1979)
    Springer
    Calcified tissue international 27 (1979), S. 129-135 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Osteoclasts ; Electron microscopy ; Morphometry ; Metaphysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of parathyroid hormone (PTH) on the size of the osteoclasts, nuclei, ruffled borders, and clear zones in long bones of thyroparathyroidectomized (TPTX) rats were quantitated as a function of time. These data were compared with the number of osteoclasts in the bone and with plasma calcium levels. A significant increase in the average size of the ruffled borders was demonstrated 30 min after injection of 50 U of purified bovine PTH, and of the clear zones 30–90 min after PTH. This was followed at 90 min by an increase in the average size of the cells. The sizes of ruffled borders and clear zones dropped sharply to control levels after 6 h, whereas the size of the cells remained elevated up to 12 h and returned to control values at 24 h. Plasma calcium levels were increased, but not significantly, between 30 min and 6 h. An increase in the number of osteoclasts was significant after 12 h. Removal of the parathyroid glands did not diminish the normal activity of osteoclasts. In animals with intact glands injection of 50 U of PTH did not cause a significant change in cell size or resorbing apparatus. It is concluded that PTH acts to rapidly stimulate the bone resorptive activity of osteoclasts and to cause a delayed increase in their number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441175
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  • 3
    Electronic Resource
    Electronic Resource
    Sporulation and spore liberation in Aspergillus fumigatus (1977)
    Springer
    Mycopathologia 60 (1977), S. 175-177 
    Details
    ISSN: 1573-0832
    Keywords: Aspergillus fumigatus ; Spore formation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00448412
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  • 4
    Electronic Resource
    Electronic Resource
    An ultrastructural survey of the genus Prototheca with special reference to plastids (1977)
    Springer
    Mycopathologia 61 (1977), S. 117-119 
    Details
    ISSN: 1573-0832
    Keywords: Prototheca ; Colorless alga ; Plastids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An ultrastructural investigation of six different species of Prototheca showed that all of them contained starch grains enclosed in double-membrane-bounded structures recognized as plastids. It is concluded that these unicellular species of Prototheca must be considered as non-photosynthetic algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00443840
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  • 5
    Electronic Resource
    Electronic Resource
    On the fungitoxicity of some new thiocyanatopyrazole derivatives: Electron microscopical study in trichophyton mentagrophytes (1976)
    Springer
    Mycopathologia 58 (1976), S. 39-47 
    Details
    ISSN: 1573-0832
    Keywords: Trichophyton mentagrophytes ; Thiocyanatopyrazole derivatives ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493592
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  • 6
    Electronic Resource
    Electronic Resource
    Formation and nature of swirl defects in silicon (1975)
    Springer
    Applied physics 8 (1975), S. 319-331 
    Details
    ISSN: 1432-0630
    Keywords: Self-interstitials in silicon ; Swirls ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Point defect agglomerates in dislocation-free silicon crystals, usually called “swirls”, have been investigated by means of high-voltage electron microscopy. It was found that a single swirl defect consists of a dislocation loop or a cluster of dislocation loops. By contrast experiments it could be shown that these loops are formed by agglomeration of self-interstitial atoms. Generally the loops have a/2〈110〉 Burgers vectors, but in specimens with high concentrations of carbon (∼1017 cm−3) and oxygen (∼1016 cm−3) also dislocation loops including a stacking fault were observed. In crystals grown at growth rates higher thanv=4 mm/min no swirls are observed; lower growth rates do not markedly affect the size and shape of the dislocation loops. With decreasing impurity content (particulary of oxygen and carbon) the swirl density decreases, whereas the dislocation loop clusters become larger and more complex. A model is presented which describes the formation of swirls in terms of agglomeration of silicon self-interstitials and impurity atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898366
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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    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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  • 11
    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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  • 12
    Electronic Resource
    Electronic Resource
    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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  • 13
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848269
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  • 14
    Electronic Resource
    Electronic Resource
    Quantitative morphogenetic investigations on fine structural changes in the optic tectum of the rainbow trout (Salmo gairdneri) during ontogenesis (1978)
    Springer
    Development genes and evolution 184 (1978), S. 83-94 
    Details
    ISSN: 1432-041X
    Keywords: Synaptogenesis ; Electron microscopy ; Visual acuity ; Fish development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The morphogenetic differentiation of synapses of the optic tectum of the rainbow trout was investigated at different stages of development (from hatching to adult) and compared with the improvement in visual discrimination (minimum separable). (1) The main phase of synaptogenesis (increase in number of synapses, length of contact zone and number of vesicles) begins about one week after hatching and continues up to the age of one month, when the larvae start swimming freely. (2) Myelination begins 26 days after hatching and induces the end of the synaptogenesis period. (3) The visual discrimination (minimum separable) of trout larvae improves from 30 degrees of arc on the 10th day after hatching to 1 degree on day 30, then to about 14 to 18 min of arc in the adult. The results are discussed with special reference to previous biochemical investigations on changes in the ganglioside composition of the trout brain during comparable periods of development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848671
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  • 15
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848885
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  • 16
    Electronic Resource
    Electronic Resource
    SEM analysis of amphibian mesodermal migration (1977)
    Springer
    Development genes and evolution 181 (1977), S. 31-40 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00857266
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  • 17
    Electronic Resource
    Electronic Resource
    Developmental potentials of the cells of the male foreleg disc ofDrosophila (1977)
    Springer
    Development genes and evolution 181 (1977), S. 309-320 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848058
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  • 18
    Electronic Resource
    Electronic Resource
    Cellular calcium distribution in fetal bones studied with K-pyroantimonate (1978)
    Springer
    Calcified tissue international 26 (1978), S. 181-190 
    Details
    ISSN: 1432-0827
    Keywords: Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013254
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  • 19
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441158
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  • 20
    Electronic Resource
    Electronic Resource
    The ultrastructure of the extracellular phase of bone as observed in frozen thin sections (1977)
    Springer
    Calcified tissue international 23 (1977), S. 215-223 
    Details
    ISSN: 1432-0827
    Keywords: Amorphous mineral ; Bone ; Electron microscopy ; Ultracryotomy ; Ultramicro-incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 μm in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO4 vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012788
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    The fine structure of decalcified cartilage and bone: A comparison between decalcification procedures performed before and after embedding (1978)
    Springer
    Calcified tissue international 25 (1978), S. 179-190 
    Details
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Calcified matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The ultrastructure of calcifying cartilage and bone has been examined under the electron microscope after using three different methods of decalcification. The first was carried out before embedding (by soaking specimens in EDTA or formic acid), the second after embedding (by floating ultrathin sections on formic acid), and the third after embedding (by soaking embedded specimens in EDTA or formic acid), and with later re-embedding. The first procedure invariably induces drastic changes in the fine structure of the cells and calcified matrix, probably as a results of the extraction of organic material along with extraction of mineral. The second and third procedures make it possible to preserve ultrastructural details perfectly in both cells and calcified matrix. Of the two, the third procedure is preferable because of its greater simplicity. In areas that are still calcifying, these post-embedding decalcification techniques reveal the presence of crystal-associated, filamentous organic structures which are not recognizable in specimens decalcified before embedding. These structures, which could have a key role in inducing and regulating crystal formation and growth, are less evident in fully calcified areas (but not at their borders). This may partly be due to the loss of glycan components in the matrix during calcification. The most important determinant, however, seems to be the fact that during calcification the components of the matrix, including collagen fibrils, are involved in an aggregation process which reduces the amounts of free chemical groups available for reaction with the stain solution. Because post-embedding decalcification does not disturb this state of aggregation, the stainability of the matrix and the electron microscopic evidence of its components remain very low.
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    URL: http://dx.doi.org/10.1007/BF02010766
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    Ultrastructural study of amelogenesis imperfecta (1977)
    Springer
    Calcified tissue international 24 (1977), S. 191-197 
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    ISSN: 1432-0827
    Keywords: Amelogenesis imperfecta ; Hypocalcification ; Hypoplasia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An ultrastructural study of teeth with amelogenesis imperfecta revelaed various aspects of microcavities in the enamel surface, which ranged from isolated imprints of ameloblasts corresponding to the mildest lesions at the end of amelogenesis, to pits caused by the death of 20 to 30 ameloblasts at the beginning of amelogenesis. Abnormalities in the shape of the prisms can be observed. Further, crystals are distributed randomly within a prism or at the junction of 2 contiguous prisms while intercrystalline spaces are widened, indicating in various places the lack of a preferred orientation of the crystals. In amelogenesis imperfecta, two different crystalline periods are found: 1 of about 250 Å, the other of about 500 Å and over. The fact that amorphous areas are found among the crystals of enamel may be related to different stages of crystallization. However, it was not possible to find any lattice defect.
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    URL: http://dx.doi.org/10.1007/BF02223315
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    Further observations on the fine structure of cellular cementum from deciduous teeth of pigs (1977)
    Springer
    Calcified tissue international 24 (1977), S. 239-242 
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    ISSN: 1432-0827
    Keywords: Cementum ; Lysis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Examination of microradiographs from the deciduous teeth of pigs revealed large lacunae or radiolucent zones close to the cemento-dentinal junction. Electron microscopic studies of the ground sections showed areas or irregularly shaped zones devoid of mineral and filled with collagen fibers. In the wide unmineralized zones, spherical clusters of crystallites were noted. Several cementum lacunae bordered by a broad rim of unmineralized collagen fibers were noted and some lacunae also contained zones of a moderately electron dense material. This material did not yield a diffraction pattern, while the mineralized part of the cementum gave the diffraction pattern typical of hydroxyapatite.
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    URL: http://dx.doi.org/10.1007/BF02223322
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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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    URL: http://dx.doi.org/10.1007/BF02013264
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    Scanning electron microscopical study on the fluorosis of enamel in rats (1978)
    Springer
    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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    URL: http://dx.doi.org/10.1007/BF02010754
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    The crystal sheaths from bivalve hinge ligaments (1978)
    Springer
    Calcified tissue international 25 (1978), S. 45-51 
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    ISSN: 1432-0827
    Keywords: CaCO3 ; Amino acids ; Sheaths ; Ligament ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The aragonite crystals in the molluscan bivalve hinge ligament are surrounded by an organic sheath which is distinct from the remainder of the ligament matrix. Methods have been developed to isolate these sheathed crystals from the ligaments ofSpisula solidissima andMercenaria mercenaria employing a papain digestion of the matrix protein. The sheathed crystals fromSpisula have a CaCO3/protein ratio of 11.1 and those fromMercenaria a ratio of 29.6. The sheathed crystals and the empty crystal sheaths have been examined by electron microscopy for structural integrity. The sheath proteins exhibit much smaller proportions of the amino acids glycine and methionine than the hinge ligaments. These are characteristic amino acids of high concentration in the hinge ligaments of both species. The concentrations of acidic and basic amino acids are increased about two fold in the sheaths over those of the ligaments. Otherwise there is little similarity in the amino acid composition of the sheaths in the two species. However, SDS electrophoresis shows the sheaths of both to contain a major protein component with a molecular weight of about 25,000. The sheath protein from theMercenaria ligament contains about 5% carbohydrate and that ofSpisula sheaths less than 1% carbohydrate.
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    URL: http://dx.doi.org/10.1007/BF02010750
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    Orientation of apatite in single osteon samples as studied by pole figures (1979)
    Springer
    Calcified tissue international 29 (1979), S. 101-105 
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    ISSN: 1432-0827
    Keywords: Osteon ; X-ray diffraction ; Pole figures ; Electron microscopy ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The X-ray diffraction method based on pole figures has been applied to single osteon samples in order to obtain information about the texture of the inorganic bone fraction and the way it changes during calcification. The osteon samples were cylindrically shaped, with axes corresponding to those of the haversian canals. Selection was carried out according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteons were selected: longitudinal, alternate, and transversal. The results indicate that in all three types of osteons, the long axis of the sample is apparently the only direction of orientation because the transversally oriented crystallites give an isotropic diffuse scattering as would be expected if all the inorganic particles were irregularly oriented around the osteon axis. The number of longitudinally oriented crystallites increases progressively from transversally oriented osteons to alternately and longitudinally oriented ones. The crystallite orientation in an axial direction increases in fully calcified osteons. This last result is in agreement with the electron microscopic finding that the long needle-shaped crystallites covering much more than a major collagen period and measuring 40–45 Å in width increase in number as calcification proceeds.
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    URL: http://dx.doi.org/10.1007/BF02408064
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    X-ray diffraction and electron microscope study of osteons during calcification (1978)
    Springer
    Calcified tissue international 25 (1978), S. 133-143 
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    ISSN: 1432-0827
    Keywords: Osteon ; X-Ray diffraction ; Electron microscopy ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To obtain information on the changes in the inorganic bone fraction during calcification, low- and wide-angle X-ray diffraction techniques and electron microscopy have been applied to single osteon samples. The samples were cylindrically shaped and their axes corresponded to the axes of the Haversian canals. The selection was made according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteon were selected, that is, longitudinally structured osteons, transversely structured osteons, and alternately structured osteons. The results indicate that in osteonic lamellar bone there are two types of inorganic particles: (1) granules arranged in linear or needle-shaped entities with maximum width 40–45 Å, which are regularly distributed at the level of the main band of the collagen fibrils where their maximum length reaches the length of the main band itself; that is, about 400 Å; and (2) very long crystallites, with a diameter of 40–45 Å, which grow with their crystallographicc-axis parallel to the collagen fibrils and cover much more than a major collagen period.
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    URL: http://dx.doi.org/10.1007/BF02010762
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    Structure and association of wall fibrils produced by regenerating tobacco protoplasts (1979)
    Springer
    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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    URL: http://dx.doi.org/10.1007/BF00388233
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    Purification, some properties and quaternary structure of thed-ribulose 1,5-diphosphate carboxylase ofAlcaligenes eutrophus (1976)
    Springer
    Archives of microbiology 110 (1976), S. 157-166 
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    ISSN: 1432-072X
    Keywords: d-Ribulose 1,5-diphosphate carboxylase ; Oxygenase activity ; Quaternary structure ; Electron microscopy ; Alcaligenes eutrophus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract d-Ribulose 1,5-diphosphate carboxylase has been purified from autotrophically grown cells of the facultative chemolithotrophic hydrogen bacteriumAlcaligenes eutrophus. The enzyme was homogeneous by the criteria of polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 505000 determined by gel filtration and sucrose density gradient centrifugation, and a sedimentation coefficient of 18.2 S was obtained. It was demonstrated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis that the enzyme consists of two types of subunits of molecular weight 52000 and 13000. Electron microscopy on the intact and the partially dissociated enzyme lead to the construction of a model for the quaternary structure of the enzyme which is composed of 8 large and 8 small subunits. The most probable symmetry of the enzyme molecule is 4:2:2. Michaelis constant (K m ) values for ribulose 1,5-diphosphate, Mg2-, and CO2 were 0.59 mM, 0.33 mM, and 0.066 mM measured under air. Oxygen was a competitive inhibitor with respect to CO2 suggesting that the enzyme also exhibits an oxygenase activity. The oxygenolytic cleavage of ribulose 1,5-diphosphate was shown and a 1:1 stoichiometry between oxygen consumption and 3-phosphoglycerate formation observed.
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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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    Dorsal-ventral differentiation in Simonsiella and other aspects of its morphology and ultrastructure (1977)
    Springer
    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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    Isolation of lipopolysaccharides and the effect of Polymyxin B on the outer membrane of Corynebacterium autotrophicum (1978)
    Springer
    Archives of microbiology 118 (1978), S. 67-69 
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    ISSN: 1432-072X
    Keywords: Corynebacterium autotrophicum ; Outer Membrane ; Lipopolysaccharides ; Biochemical analysis ; Polymyxin B ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lipopolysaccharides (LPS) from Corynebacterium autotrophicum were isolated and analyzed. Autotrophically grown cells contained 2–5 mg of partly purified LPS per g dry weight of lyophilized cells. Serological cross reaction with Lipid A antigen of Salmonella minnesota confirmed the presence of LPS in C. autotrophicum. Electron microscopy of negatively stained Polymyxin B-treated cells showed formation of blebs on the Outer Membrane indicating an interaction of Polymyxin B specifically with LPS. Up to now, no Gram-positive organisms are known which contain any LPS. Thus, C. autotrophicum, though giving opposite results when the Gram-staining reaction was applied by several authors, has to be classified into the group of Gram-negative bacteria.
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    Characteristics of a cholera phage (1978)
    Springer
    Archives of microbiology 119 (1978), S. 303-304 
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    ISSN: 1432-072X
    Keywords: Vibrio cholera phage group II ; Properties ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The basic physical, chemical and physiological properties of a group II cholera phage belonging to Mukerjee's classification has been described.
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    Acetobacter bacteriophage A-1 (1979)
    Springer
    Archives of microbiology 121 (1979), S. 193-197 
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    ISSN: 1432-072X
    Keywords: Acetobacter suboxydans ; Bacteriophage A-1 ; Restriction ; Modification ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bacteriophage ofAcetobacter suboxydans was isolated and found to correspond to type A phage according to Bradley's classification. The phage contains double stranded DNA. The length of the latency period and burst size could not be precisely determined because of apparent non-synchronous release of phage from single infective cycles. The host range was determined using 24 strains ofAcetobacter andGluconobacter species. Evidence for a probable occurence of host determined restriction and modification was obtained withAcetobacter suboxydans strain ATCC 621. The phage is designated A-1 and it is the first one to be reported forAcetobacter.
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    Bdellovibrio-like parasite of cyanobacteria symbiotic in marine sponges (1979)
    Springer
    Archives of microbiology 123 (1979), S. 101-103 
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    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Cyanobacteria ; Marine sponges ; Symbiosis ; Infection ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bdellovibrio-like bacterium was observed infecting unicellular symbiotic cyanobacteria in two coral reef sponges, Neofibularia irata and Jaspis stellifera. The infecting bacterium, which was located between the cell wall and the cytoplasmic membrane of the cyanobacteria, was similar in size and appearance to previously described bdellovibrios. This observation is believed to extend the host range of the bdellovibrios.
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    Origin and ultrastructure of intra-hyphal hyphae in Trichophyton terrestre and T. rubrum (1975)
    Springer
    Archives of microbiology 106 (1975), S. 195-200 
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    ISSN: 1432-072X
    Keywords: Trichophyton terrestre ; Trichophyton rubrum ; Hyphal fusions ; Origin of intra-hyphal hyphae ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cell observation chamber was designed to perform continuous photomicroscopic observations of hyphal anastomosis and the origin of intra-hyphal hyphae in Trichophyton terrestre and T. rubrum. These data were correlated with ultrastructural features of intra-hyphal hyphae. Hyphal fusions occurred commonly in either species of Trichophyton when incubated alone. In T. terrestre, empty hyphal segments adjoined by live units were invaded at the septa from both directions by new hyphal ingrowth. Continuous observations revealed that the intra-hyphal hyphae subsequently anastomosed via a lateral fusion peg. Similar intra-hyphal hyphae were shown in T. rubrum. Electron microscopic studies revealed ascomycetous septa in both conventional hyphae and intra-hyphal hyphae. For the latter, the cytoplasm and wall of the inner hypha were bounded by cytoplasmic organelles and another cell wall of the outer hypha.
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    Physiology and fine structure of sporangiospore germination in Piptocephalis unispora prior to infection (1976)
    Springer
    Archives of microbiology 107 (1976), S. 99-107 
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    ISSN: 1432-072X
    Keywords: Piptocephalis unispora ; Mucorales ; Kickxellaceae ; Electron microscopy ; Germination ; Spore swelling ; Sporangiospore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germination of the sporangiospore of Piptocephalis unispora Benjamin, observed by means of light and electron microscopy, involved the formation of a new inner wall which became continous with the inner layer of the wall of the germ tube. The outer wall layer of the germ tube was continous with the original inner wall layer of the dormant spore. Preliminary details of appressorium structure were noted. Nutritional experiments indicated that sporangiospores required external sources of utilisable nitrogen and carbon compounds for maximal swelling and germ tube production. Limited development occurred when either nutrient was supplied singly. Comparison of germination of the asexual spore with that in other Mucorales, especially the Kickxellaceae, has been made, and the merosporangial status in P. unispora discussed.
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    Microfilament bundles in antheridial nuclei of Achlya ambisexualis E 87 (1976)
    Springer
    Archives of microbiology 107 (1976), S. 113-114 
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    ISSN: 1432-072X
    Keywords: Achlya ; Electron microscopy ; Nuclear microfilaments ; Antheridia ; Mycology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first report of intranuclear microfilaments within gametangial nuclei of oömycetous fungi. Longitudinal sections of four to six microfilaments were frequently observed in meiotic antheridial nuclei of Achlya ambisexualis. Each microfilament measured approximately 7–10 nm in diameter. Spindle tubules (25 nm in diameter) were also observed within some of the nuclei possessing microfilaments.
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    Electron microscopy of isolated cell walls of Bacillus subtilis var. niger (1976)
    Springer
    Archives of microbiology 109 (1976), S. 195-197 
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    ISSN: 1432-072X
    Keywords: Cell wall ; Peptidoglycan ; Electron microscopy ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolated cell walls of Bacillus subtilis have a striated appearance in the electron microscope. The structure persists when teichoic acids are removed. It is inferred that the structure bears on the arrangement of the peptidoglycan chains.
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    Detection of small cryptic plasmids in Salmonella typhimurium strain LT2 (1978)
    Springer
    Archives of microbiology 119 (1978), S. 87-90 
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    ISSN: 1432-072X
    Keywords: Salmonella typhimurium strain LT2 (ColIb) ; Cryptic plasmids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Small cryptic plasmids of molecular weights ranging from 1 to 3 Mdal were detected by electron microscopy in Salmonella typhimurium strain LT2 (ColIb). They were divided into different size classes. Two of the cryptic plasmids were transferred simultaneously with ColIb to Escherichia coli.
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    Electron microscopy of the cell wall complex ofMethylomonas albus (1978)
    Springer
    Archives of microbiology 119 (1978), S. 227-229 
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    ISSN: 1432-072X
    Keywords: Cell wall ; Electron microscopy ; Methylomonas albus ; Goblet sub-units
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In surface view, the cell wall complex ofMethylomonas albus possesses a hexagonal pattern of ridges. Thin sections reveal a continuous layer of goblet-shaped elements attached to the outermost surface of the lipopolysaccharide membrane. A possible interpretation of the cell wall complex ofM. albus, based on the fine-structural data is presented.
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    Electron microscopic study on the quaternary structure of the isolated particulate alcohol-acetaldehyde dehydrogenase complex and on its identity with the polygonal bodies of Clostridium kluyveri (1979)
    Springer
    Archives of microbiology 120 (1979), S. 255-262 
    Details
    ISSN: 1432-072X
    Keywords: Alcohol dehydrogenase ; Acetaldehyde dehydrogenase ; Clostridium kluyveri ; Electron microscopy ; Polygonal bodies ; Enzyme complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alcohol-acetaldehyde dehydrogenase complex of Clostridium kluyveri has been separated from contaminating β-hydroxybutyryl-CoA dehydrogenase by repeated precipitation with manganese and ammonium sulfate. Mn++ was required for maximum alcohol dehydrogenase activity. The molecular weight of the enzyme complex was 194,000 as determined by sucrose density gradient centrifugation. The enzyme complex has been shown to contain two types of subunits with molecular weights of 55,000±2,600 and 42,000±1,200, respectively which are arranged in “H”-shaped particles. In solutions with an ionic strength above 25 mM the enzyme complex precipitated in the form of lumps as has been shown with specific ferritin-conjugated antibodies. These lumps are assumed to be aggregated polygonal bodies present in C. kluyveri.
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    Penetration of Phytophthora cinnamomi into disease tolerant and susceptible eucalypts (1976)
    Springer
    Archives of microbiology 108 (1976), S. 231-242 
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    ISSN: 1432-072X
    Keywords: Phytophthora ; Penetration ; Eucalypts ; Roots ; Electron microscopy ; Appressoria ; Plugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms of penetration of Phytophthora cinnamomi Rands into seedling eucalypt roots were studied by light and electron microscopy. Culture grown seedlings of root-rot tolerant Eucalyptus st johnii and root-rot susceptible Eucalyptus obliqua were inoculated with both zoospores and mycelium. Zoospores encysted on roots of both species and the germ tubes penetrated without the formation of appressoria. Swellings, previously described as appressoria, were formed when the germ tube was slow to enter the host by intracellular penetration. Vegetative hyphae penetrated both inter- and intracellularly into the zones of root elongation and differentiation, often through root hairs. Evidence of hydrolysis of the host cell-wall at the point of penetration was observed in electron micrographs. Several hours after the germ tube penetrated the epidermis, a thick plug of amorphous material formed in the germ tube slightly below the level of the outer walls of the epidermal cells, sealing off the hypha within the root. Behaviour of zoospores and germ tubes and the mechanism of penetration were similar on both hosts. Micrographs do not suggest any kind of a hypersensitive reaction by the host cells during the early stages of infection.
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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)
    Springer
    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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    The fine structure of Micrococcus radiophilus and Micrococcus radioproteolyticus (1976)
    Springer
    Archives of microbiology 107 (1976), S. 313-320 
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    ISSN: 1432-072X
    Keywords: Micrococcus radiophilus ; Micrococcus radioproteolyticus ; Bacterial cell walls ; Fine structure ; Electron microscopy ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The radiation resistant bacteria Micrococcus radiophilus and M. radioproteolyticus were studied by thin sectioning and freeze-etching techniques and the two species were found to be similar in the fine structure. The only significant difference was in the appearance of the surfaces of the cell walls in freeze-etched preparations. Since the two species, together with M. radiodurans, possess a unique cell wall structure and a cell wall peptidoglycan, which is different from that of other micrococci and Gram-positive cocci, it is recommended that they be reclassified into a new genus.
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    Alterations in the cell wall of Spirillum serpens VHL early in its association with Bdellovibrio bacteriovorus 109D (1976)
    Springer
    Archives of microbiology 108 (1976), S. 55-64 
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    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Spirillum ; Cell wall ; Bdelloplast ; Lipoprotein ; Peptidoglycan ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In both freeze-etched and critical-point dried preparations examined by transmission and scanning electron microscopy, respectively, the outer surfaces of the cells of Spirillum serpens VHL assume a wrinkled appearance 10–15 min after challenge by Bdellovibrion bacteriovorus 109D. This wrinkling effect is believed (on circumstantial evidence) to be caused by the bdellovibrio's disruption of the cell wall lipoprotein of the Spirillum. With the exception of those topological changes caused by wrinkling, the outer membrane of the Spirillum cell wall retains a normal appearance as viewed in freeze-etched preparations, even after the Spirillum cell has been converted into a bdelloplast. Although the peptidoglycan layer of the Spirillum cell presumably is weakened somewhat by the invading Bdellovibrio, evidence obtained from freeze-fractured preparations of Spirillum bdelloplasts suggests that the peptidoglycan remains as a discrete cell wall layer, even though the Spirillum cell wall apparently has lost much of its rigidity. That the peptidoglycan backbone remains essentially intact, even after the Spirillum cell has been entered by the Bdellovibrio, is supported by the observation that the soluble amino sugar content of the culture medium, as determined by chemical analysis, does not rise even 5.0 h after the association of the Bdellovibrio with the Spirillum has begun.
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    The cytology of the gametes and fertilization of Allomyces macrogynus (1976)
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    Archives of microbiology 109 (1976), S. 21-30 
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    ISSN: 1432-072X
    Keywords: Electron microscopy ; Allomyces ; Gametes ; Fertilization ; Membrane fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gametes and the process of fertilization were examined by light and electron microscopy in the lower eukaryote Allomyces macrogynus. Differences in gamete morphology included the overall larger size and the presence of a larger nuclear apparatus, along with the association of a side-body complex and many more mitochondria in the female gamete. In this species of Allomyces, fertilization was initiated by contact and fusion of specialized regions of the gamete plasma membranes resulting in a binucleate fusion cell surrounded by plasma membrane contributed by both partners. Following plasmogamy, nuclear fusion was initiated by multiple nuclear membrane contacts between adjacent outer membranes. Following inner membrane fusion, small nucleoplasmic bridges were observed which presumably fused with one another and resulted in a single bridge which widened, forming the mature diploid nucleus. After karyogamy, fusion of the nuclear caps did not always occur and zygotes with and without fused caps were observed. Coalescence of the nucleoli completed the events of fertilization, forming a zygote with a single nuclear apparatus (sometimes with two caps) and two flagella. These observations are discussed in relation to fertilization mechanisms and compared to fertilization in other organisms.
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    Electron microscopic investigation of the hydrogen-oxidizing acetate-forming anaerobic bacterium Acetobacterium woodii (1977)
    Springer
    Archives of microbiology 115 (1977), S. 207-213 
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    ISSN: 1432-072X
    Keywords: Acetobacterium woodii ; Hydrogen-oxidizing acetate-forming anaerobe ; Fine structure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetobacterium woodii is a Gram-positive anaerobic nonsporeforming bacterium able to grow on H2 and CO2 as sole sources of energy. The product of fermentation is acetic acid. Fine structural analysis showed rod-shaped flagellated cells, and coccoid cells without flagella arranged predominantly in pairs and chains. The cell wall was found to be composed of three layers. The cell surface exhibited a periodic array of particles consisting of subunits. The cytoplasmic membrane showed particles either either in random distribution or in a hexagonal pattern. Intracytoplasmic membranes were rarely observed, whereas inclusion bodies of varying shapes, predominantly in an uncommon disc-shape, could frequently be observed. Their content was dissolved in ultrathin sections indicating hydrophobic nature.
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    Isolation and partial characterization of normal and defective bacteriophages of gram-negative hydrogen bacteria (1977)
    Springer
    Archives of microbiology 115 (1977), S. 237-247 
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    ISSN: 1432-072X
    Keywords: Defective lysogeny ; Alcaligenes eutrophus ; Simultaneous isolation technique ; Temperate bacteriophages ; Pseudomonas pseudoflava ; Biological characterization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Widespread defective lysogeny was detected in Alcaligenes eutrophus by electron microscopic analysis of cultures. Mitomycin C treatment of the cultures resulted in the production of defective (inco-) particles. Polysheaths were produced both with and without induction. With the simultaneous isolation technique six phages were isolated for hydrogen-oxidizing strains of the new species Pseudomonas pseudoflava. The phages were able to replicate under autotrophic conditions and were found to have a very restricted host range. Electron microscopic analysis allowed classification into two structural groups. Group I contained phages with contractile tails; group II contained phages with flexible, noncontractile tails. All but one (gb) of the new phages were shown to be temperate by isolation of lysogens and induction with mitomycin C.
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    R-Bodies in newly isolated free-living hydrogen-oxidizing bacteria (1979)
    Springer
    Archives of microbiology 121 (1979), S. 9-15 
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    ISSN: 1432-072X
    Keywords: R-Bodies ; Kappa particles ; Free-living hydrogen bacteria ; Induction ; Electron microscopy ; Chemical composition ; Defective prophages ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract R-Bodies have been found in a recently isolated pseudomonas-like free-living hydrogen oxidizing bacterium. Their isolation, fine structure and chemical composition are described and compared with the R-bodies from the kappa particles (Caedobacter), obligate endosymbionts of Paramecium aurelia. The 2K 1 R-bodies exhibited essential characteristics of the kappa R-bodies; however, their size and some other structural aspects proved that they represent a new type of R-bodies. The presence of phage tail-like particles in cells induced with Mitomycin C is in favour of the hypothesis that the R-bodies might be coded by defective prophages, or by extrachromosomal elements.
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    Micro-autoradiographic studies on host-parasite interactions (1975)
    Springer
    Archives of microbiology 105 (1975), S. 193-199 
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    ISSN: 1432-072X
    Keywords: Bean ; Rust ; Haustorium ; Sheath ; Autoradiography ; Infection ; Electron microscopy ; Phaseolus vulgaris ; Uromyces phaseoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tritium labeled uredospores of Uromyces phaseoli were produced be feeding the host, Phaseolus vulgaris, with 3H-orotic acid. These spores were allowed to germinate on and to penetrate into a bean leaf. 24 hrs after inoculation, the bean rust had formed the first haustorium. All fungal structures, including the fungus walls, were heavily labeled. No label could be detected in the cells that had come into contact with the hyphae. In the infected host cell, the haustorium was labeled heavily, but the sheath around the haustorium and the host cell remained free of label. These results indicate that no detectable amounts of label leach from the bean rust into the host at this stage of infection although it is known that the rust takes up many metabolites. Since the sheath remains free of label and all fungal structures are evenly labeled, it is concluded that the sheath is formed by the host.
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    Structure and composition of intracytoplasmic membranes of Ectothiorhodospira mobilis (1976)
    Springer
    Archives of microbiology 107 (1976), S. 167-182 
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    ISSN: 1432-072X
    Keywords: Ectothiorhodospira mobilis ; Photosynthetic membranes ; Electron microscopy ; Isolation of membranes ; Structure of membranes ; Composition of membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein. Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching. Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10–15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.
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    The mitochondrial complex in cryptophyceae (1977)
    Springer
    Archives of microbiology 112 (1977), S. 207-218 
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    ISSN: 1432-072X
    Keywords: Cryptophyceae ; Algae ; Hemiselmis rufescens ; Chroomonas ; Cryptomonas ; Mitochondrial complex ; Cristae ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unitary nature of the mitochondrion and the characteristic flattened finger-like morphology of the cristae were demonstrated in the Cryptophyceae. Hemiselmis rufescens contained an unbranched vermi-form mitochondrion in contrast to the variously branched complex, comprising an interconnected peripheral and central reticulum, in Chroomonas sp. and strains of Cryptomonas. The systematic value of the shape and distribution of the mitochondria in the examined genera was suggested.
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    Effect of carbon dioxide on pigment and membrane content in Synechococcus lividus (1977)
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    Archives of microbiology 115 (1977), S. 185-198 
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    ISSN: 1432-072X
    Keywords: Synechococcus lividus ; Cyanobacteria ; Carbon dioxide ; Electron microscopy ; Bleaching-regreening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of carbon dioxide on pigment and membrane content in Synechococcus lividus was studied by depriving cells of CO2 and examining cell populations biochemically and by electron microscopy. After 120 h of CO2 deprivation, S. lividus lost all detectable chlorophyll a and C-phycocyanin. Such bleached cultures were “mustard yellow”, the result of approximately 1.8 times more carotenoid per cell than green control cultures. Although cells from beached cultures appeared morphologically identical to control green cells when examined by light microscopy, electron microscopic examination revealed them to be devoid of detectable thylakoid membrane. Thylakoid membrane could not be recovered by physical isolation or revealed by freeze etching of bleached S. lividus. In addition, inclusion bodies characteristically found in S. lividus were also absent. Reintroduction of CO2 into bleached cultures resulted in a rapid resynthesis of both chlorophyll a and C-phycocyanin. Electron microscopic examination of these regreening cultures revealed that thylakoid membrane was also rapidly resynthesized. Growth of regreened cultures did not occur until there was the synthesis of a full complement of chlorophyll a, C-phycocyanin, and thylakoid membrane. A time course study of the cytological events occurring during bleaching and regreening is presented.
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    Intracelluläre Organisation phagenschwanz-ähnlicher Bacteriocine der Gruppe A in Serratia marcescens (1976)
    Springer
    Archives of microbiology 111 (1976), S. 175-183 
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    ISSN: 1432-072X
    Keywords: Serratia marcescens ; (Phage tail) bacteriocin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Genese eines phagenschwanzähnlichen Bacteriocins in Zellen des Gruppe A-bacteriocinogenen (bA+) Serratia marcescens-Stammer Nr. 16 wurde nach Mitomycin C (MC) Induktion elektronenoptisch untersucht. Dieses Bacteriocin (Gesamtlänge 117 nm) besteht aus einem hohlen Stift mit kontraktiler Scheide. Nach 60 min Induktion wurden in Dünnschnitten stäbchenförmige Bacteriocine identifiziert. Sie erscheinen in drei Aggregationsformen: 1. als hexagonale Einschlüsse, 2. als Bänder dicht nebeneinanderliegender Bacteriocine und 3. als Stapel von übereinanderliegenden Bacteriocinschichten, wenn nach 120 min Induktion ein Maximum von ca. 450 Bacteriocinen pro Zelle erreicht wird. Bacteriocine konnten nach der gleichen Induktionszeit von 60 min auch mit der “in situ lysis technique” nachgewiesen werden. Neben Bacteriocinen traten relativ selten und unregelmäßig auch Phagenköpfe auf. Die Stäbchenform teilungsfähiger Zellen blieb bis zum Auftreten von intracellulären Bacteriocinen erhalten. Ihre Umwandlung in geblähte, sphäroplastenähnliche Zellformen, die nach 120 min Induktion lysierten, war zeitlich korreliert mit Feinstrukturveränderungen der Zellwand.
    Notes: Abstract The biosynthesis of a phage tail-like Bacteriocin by cells of the group A-bacteriocinogenic (bA+ Serratia marcescens strain no. 16 after induction with mitomycin C (MC) was examined electronmicroscopically. This bacteriocin (total length 117 nm) consists of a hollow core and a contractile sheath. At 60 min following induction, rod-like bacteriocin-partieles were identifiable in ultrathin sections. The particles were found to comprise three morphologically different forms of aggregation: 1. hexagonal inclusions, 2. contiguous, bank-like particles, and 3. staples of superimposed layers of bacteriocin particles. At 120 min after induction bA+ cells revealed maximally 450 bacteriocin particles. Similarly, the phage tail particles could be demonstrated with the “in situ lysis technique” at 60 min following induction. Occasionally, phage heads were demonstrable, but in no instance were complete phage particles discernible. Dividing cells of the bA+ strain of S. marcescens maintained their rod-form following induction with MC until intracellular phage tail bacteriocin particles were seen. However, at 120 min after induction, the swollen, sphaeroplast-like cells lysed, an event that could be correlated with fine structural alterations of the cell wall.
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    Ultrastructure of carotenoid mutant strain R-26 of Rhodopseudomonas sphaeroides (1978)
    Springer
    Archives of microbiology 118 (1978), S. 305-308 
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    ISSN: 1432-072X
    Keywords: Carotenoid mutant strain R-26-Rhodopseudomonas sphaeroides ; Electron microscopy ; Intracellular membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stained thin-sections and freeze-fractured preparations of the carotenoid-less mutant strain R-26 of Rhodopseudomonas sphaeroides grown photosynthetically revealed 2 morphological kinds of intracellular membrane systems- spherical vesicles distributed throughout the cytoplasm and lamellae confined to the periphery of the cell. The lamellar membranes appeared to be large, flattened vesicles.
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    Development and ultrastructure of the marine, parasitic oomycete, Lagenisma coscinodisci Drebes (Lagenidiales) (1978)
    Springer
    Archives of microbiology 116 (1978), S. 133-139 
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    ISSN: 1432-072X
    Keywords: Lagenisma ; Coscinodiscus ; Infection ; Endosymbiotic bacteria ; Tip growth ; Wall-less thallus ; Host-parasite interface ; Membranes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lagenisma coscinodisci is diplanetic and has two different cyst stages. The secondary cyst has a uniform cell wall of fibrillar material. It attaches to a Coscinodiscus frustule and germinates with an infection tube. The cyst becomes filled with an enlarging expulsion vacuole. The infection tube penetrates the diatom cell between the cingula. Inside the host cell the fungus grows as an irregularly branched wall-less thallus. In the hyphae apical vesicles are lacking. The infection tube is plugged by wall material. There are no microtubules which might participate in the morphogenesis of the thallus. The plasmalemma of the diatom is pushed inward but not pierced by the fungus. Along the host-parasite interface it lies closely paralled to the Lagenisma plasmalemma which is extremely straight here and measures about 10 nm instead of about 5–6 nm at the surfaces of other stages. The Coscinodiscus plasmalemma disintegrates at about the same time when the cytoplasm breaks down. The fungus allows bacteria to enter the diatom; there are also endosymbiontic bacteria in unattacked cells — The growth mechanisms are discussed and the host-parasite interface is compared with that of other fungi.
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    The cell cycle of Bacillus subtilis as studied by electron microscopy (1979)
    Springer
    Archives of microbiology 123 (1979), S. 173-181 
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    ISSN: 1432-072X
    Keywords: Bacillus subtilis ; Cell cycle ; DNA replication ; Cell division ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus subtilis strain Marburg was grown exponentially with a doubling time of 65 min. To follow the time course of various cell cycle events, cells were collected by agar filtration and were then classified according to length. The DNA replication cycle was determined by a quantitative analysis of radioautograms of tritiated thymidine pulse labeled cells. The DNA replication period was found to be 45 min. This period is preceded and followed by periods without DNA synthesis of about 10 min. The morphology and segregation of nucleoplasmic bodies was studied in thin sections. B. subtilis contains two sets of genomes. DNA replication and DNA segregation seem to go hand in hand and DNA segregation is completed shortly after termination of DNA replication. Cell division and cell separation were investigated in whole mount preparations (agar filtration) and in thin sections. Cell division starts about 20 min after cell birth; cell separation starts at about 45 min and before completion of the septum.
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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 
    Details
    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)
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    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)
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    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)
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    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)
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    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 
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    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)
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    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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    URL: http://dx.doi.org/10.1007/BF00484776
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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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    URL: http://dx.doi.org/10.1007/BF00483752
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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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    URL: http://dx.doi.org/10.1007/BF00484476
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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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    URL: http://dx.doi.org/10.1007/BF00498891
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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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    URL: http://dx.doi.org/10.1007/BF00486021
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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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    URL: http://dx.doi.org/10.1007/BF00484929
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00484872
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00484734
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    Mutagenesis at the cinnabar locus in Drosophila melanogaster (1978)
    Springer
    Biochemical genetics 16 (1978), S. 855-865 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00483738
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00484480
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00498975
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    Structural and functional analysis of the scute locus in Drosophila melanogaster (1979)
    Springer
    Theoretical and applied genetics 55 (1979), S. 231-238 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00268117
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    Distribution and fine structure of the lymphatic system in the human testis (1979)
    Springer
    Cell & tissue research 200 (1979), S. 15-27 
    Details
    ISSN: 1432-0878
    Keywords: Lymph vessels ; Testis ; Man ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2μm. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.
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    URL: http://dx.doi.org/10.1007/BF00236883
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    The tanycyte of the rat median eminence (1979)
    Springer
    Cell & tissue research 200 (1979), S. 329-334 
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    ISSN: 1432-0878
    Keywords: Median eminence ; Axon terminals ; Tanycytes ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present ultrastructural study proves the existence of nerve terminals closely apposed to the plasmalemmata of tanycytes in the rat median eminence. Several of these “axo-tanycytic” endings display remarkable accumulations of agranular endoplasmic reticulum in the form of pleomorphic vesicles which are closely apposed on either side of the plasma membrane of each cell compartment. Some of these vesicular profiles give the impression of structural continuity across both membrane systems. This phenomenon is discussed in the context of being a potential substratum for communication between both cell compartments.
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    URL: http://dx.doi.org/10.1007/BF00236425
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    Ultrastructure of the integumental melanophores of the coelacanth, Latimeria chalumnae (1975)
    Springer
    Cell & tissue research 163 (1975), S. 383-394 
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    ISSN: 1432-0878
    Keywords: Skin pigmentation ; Melanocytes ; Melanophores ; Electron microscopy ; Latimeria (Coelacanth)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The integumental melanophores of Latimeria chalumnae were studied by light and electron microscopy. The epidermal melanophore located in the mid-epidermis consists of a round perikaryon with long slender dendrites extending into epidermal cells and intercellular spaces. The dermal melanophores occur in the loose dermal matrix underlying a relatively thick layer of collagen fibers. The dermal melanophores are usually flattened and their dendrites lie parallel to the collagen layer. Both epidermal and dermal melanophores contain oval, electron-opaque melanosomes, large mitochondria, agranular vacuoles of endoplasmic reticulum and microtubules. Microfilaments and RNP particles are less conspicuous. While the peripheral cytoplasm of both dermal and epidermal melanophores is filled with a large number of melanosomes, the perinuclear cytoplasm of many dermal melanophores is occupied by premelanosomes in various stages of differentiation, and that of the epidermal melanophore contains numerous large vacuoles. Despite the scarcity of epidermal melanophores, the epidermal melanin unit is present in the form of melanosome complexes. In addition, the melanophores of Latimeria possess the basic characteristics common to other vertebrates, but they more closely resemble those of lungfish and other aquatic vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00219472
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    Comparative histochemical and electron microscopic studies of the sinus and venous walls of the human spleen with special reference to the sinus-venous connections (1975)
    Springer
    Cell & tissue research 163 (1975), S. 519-533 
    Details
    ISSN: 1432-0878
    Keywords: Human spleen ; Sinus lining cells ; Pulp veins ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sinus and venous walls of normal human spleens were studied with enzyme histochemical and electron microscopic methods. Particular attention was paid to the connections between sinuses and veins. Histochemically the sinus lining cells revealed a distinct naphthol-AS-acetate-esterase activity but no reaction for alkaline phosphatase. Venous endothelial cells were positive for the latter but negative for the former enzyme. In the sinusvenous junctional area there were no endothelial cells with reactivity for both enzymes. Electron microscopically both the sinus lining cells and the venous endothelial cells could be clearly characterized and therefore easily distinguished from one another on morphological grounds. There were no clear ultrastructural indications of transitional forms between sinus lining cells and venous endothelial cells in the sinus-venous area. According to these findings, sinus lining cells represent a specialized endothelium, but one with practically no morpholgical similarities to the venous endothelium.
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    URL: http://dx.doi.org/10.1007/BF00218497
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    The fine structure of the epidermis of two species of salmonid fish, the Atlantic salmon (Salmo salar L.) and the brown trout (Salmo trutta L.) (1975)
    Springer
    Cell & tissue research 163 (1975), S. 535-543 
    Details
    ISSN: 1432-0878
    Keywords: Epidermis ; Salmonids ; Mucous cells ; Mucus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of epidermal mucous cells of two species of salmonid fish has been described. Mucous cells are, next to filament-containing cells, the most commonly encountered cells in fish epidermis. The development of the cells as they progress to the periphery has been characterised. They are initially difficult to distinguish from filament-containing cells: later, they can be recognised by the presence of much smooth-surfaced E.R. The mucigenesis and the subsequent secretion of mucus has been observed and it is essentially comparable to that which occurs in the mucous cells of the mammalian intestine. The mucous layer of the epidermal surface seems to mainly comprise of the products of these mucous cells and the “cuticle” seen in other species has not yet been observed in the salmonid species investigated here.
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    URL: http://dx.doi.org/10.1007/BF00218498
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