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  • Cryptomonas  (2)
  • Immunocytochemistry  (2)
  • Key words Extraocular muscle  (2)
  • Springer  (6)
  • American Chemical Society
  • American Chemical Society (ACS)
Collection
Keywords
Publisher
  • Springer  (6)
  • American Chemical Society
  • American Chemical Society (ACS)
  • Wiley-Blackwell  (1)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Occurrence of bacterivory in Cryptomonas, a common freshwater phytoplankter (1989)
    Springer
    Oecologia 78 (1989), S. 473-476 
    Details
    ISSN: 1432-1939
    Keywords: Plankton ; Bacterivory ; Mixotrophy ; Phagotrophy ; Cryptomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bacterivory was detected by incorporation of 0.57 μm diameter, fluorescent polystyrene beads and fluorescently labeled bacteria (FLB) in two cultured species of Cryptomonas (C. ovata and C. erosa), and a population of Cryptomonas sp in a humic, mesotrophic lake. Rates of ingestion and clearance were very low, and similar for the cultures and the in situ population. The in situ population incorporated 0.7–1.7 bacteria cell-1 h-1, thereby ingesting 0.3%–2.0% of the total bacterial numbers present in the water per day, and receiving less than 2% of its carbon content per day through bacterivory. Thus, bacterivory by Cryptomonas was quantitatively important neither as a sink for bacterial biomass, nor as a carbon source for the algal cells. Possibly, it served in the uptake of essential nutrients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378736
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  • 2
    Electronic Resource
    Electronic Resource
    Stereological study of gonadotropes in the frog, Rana pipiens, after GnRH stimulation in vitro (1990)
    Springer
    Cell & tissue research 262 (1990), S. 171-176 
    Details
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Gonadotropes ; Morphometry ; Stereology ; Rana pipiens (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous physiological results have indicated the existence of two releasable pools of gonadotropins in amphibian pituitaries: an acute releasable pool that appears independent of protein synthesis, and a storage pool involved in chronic release that depends on protein synthesis. To elucidate the ultrastructural localization of these pools and the morphological changes induced in gonadotrope cells after treatment with gonadotropin-releasing hormone, we carried out a morphometric study of immuno-identified gonadotrope cells using an in vitro superfusion system. Treatment with gonadotropin-releasing hormone induced a degranulation of small (110–255 nm) and medium (236–360 nm) secretory granules as well as hypertrophy of the endoplasmic reticulum and Golgi complex. Simultaneous incubation with gonadotropin-releasing hormone and cycloheximide inhibited the release of secretory granules although the endoplasmic reticulum and Golgi complex were hypertrophied. These morphological results strongly suggest: (1) that gonadotropin-releasing hormone induces degranulation and hypertrophy of the biosynthetic machinery in gonadotrope cells; and (2) that the activation of the endoplasmic reticulum and Golgi complex by stimulation with gonadotropin-releasing hormone is independent of protein synthesis, while the release of secretory granules is protein synthesis-dependent. In addition, the second or “storage” pool of gonadotropin is associated mainly with the small and medium secretory granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327759
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  • 3
    Electronic Resource
    Electronic Resource
    Extraocular muscle in merosin-deficient muscular dystrophy: cation homeostasis is maintained but is not mechanistic in muscle sparing (1998)
    Springer
    Cell & tissue research 292 (1998), S. 495-501 
    Details
    ISSN: 1432-0878
    Keywords: Key words Extraocular muscle ; Cation ; Muscular dystrophy ; Merosin ; dy Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Extraocular muscle is uniquely spared from damage in merosin-deficient congenital muscular dystrophy. Using a murine model, we have tested the hypothesis that the maintenance of calcium homeostasis is mechanistic in extraocular muscle protection. Atomic absorption spectroscopy has demonstrated a strong correlation between the perturbation of calcium homeostasis in hindlimb muscle that is severely damaged and the absence of changes in calcium in extraocular muscle. If, as in other skeletal muscles, extraocular muscle fibers are destabilized by merosin deficiency, we would expect an increase in total muscle calcium coupled with an adaptive response in the high capacity/speed of the sarcoplasmic reticulum of the eye muscle. However, we have not observed the expected increases in total muscle calcium content, Ca2+-ATPase activity, Na+/Ca2+ exchanger content, or smooth ER Ca2+-ATPase content that are predicted by this model. Instead, these results indicate that the increased membrane permeability that characterizes, and is potentially mechanistic in, myofiber degeneration in muscular dystrophy does not occur in merosin-deficient extraocular muscle. Thus, the high-capacity calcium-scavenging systems are not primarily responsible for extraocular muscle protection in muscular dystrophy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051078
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  • 4
    Electronic Resource
    Electronic Resource
    Immunocytochemical and ultrastructural study of the frog (Rana pipiens) pars distalis with special reference to folliculo-stellate cell function during in vitro superfusion (1989)
    Springer
    Cell & tissue research 256 (1989), S. 623-630 
    Details
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Prolactin cells ; Gonadotropic cells ; ACTH cells ; Folliculo-stellate cells ; Rana pipiens (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The colloidal gold immunocytochemical technique was used to determine the ultrastructural features of the glandular cells in the pituitaries of male frogs, Rana pipiens, both in vivo and after superfusion in vitro. Specific reactions to antisera against bullfrog gonadotropins, human prolactin, and synthetic 1–39 corticotropin allowed identification of the 3 corresponding types of glandular cells. No immunoreaction was obtained with antisera against human or ovine-growth hormone, human β-thyrotropin hormone, and bovine S-100 protein. General morphological features of these immunocytochemically identified glandular cells were similar to those of equivalent cells previously described in other amphibian species. Non-glandular folliculo-stellate cells were distinctive. In freshly removed pituitaries, these folliculo-stellate cells contained lysosome-like structures, but did not show phagocytic vacuoles in the cytoplasm; they contained many mitochondria, and the Golgi complex and endoplasmic reticulum were relatively undeveloped. After 4 or 18 h of superfusion, some immunoreactive gonadotropic, prolactin, and corticotropic cells showed degeneration and destruction. In the same gland, folliculo-stellate cells retained a viable appearance, but showed phagocytic vacuoles containing secretory granule-like structures which were immunoreactive to gonadotropic, prolactin, and corticotropic antibodies. Some folliculo-stellate cells showed phagocytic vacuoles containing complete glandular cells. These results suggest that superfusion causes a destruction of some of the glandular cells, and that folliculo-stellate cells act as phagocytes when cellular debris or moribund cells are present in the intercellular space in the pituitary parenchyma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225612
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  • 5
    Electronic Resource
    Electronic Resource
    Vestibulo-ocular pathways modulate extraocular muscle myosin expression patterns (1999)
    Springer
    Cell & tissue research 295 (1999), S. 477-484 
    Details
    ISSN: 1432-0878
    Keywords: Key words Extraocular muscle ; Muscle development ; Myosin heavy chain ; Vestibular development ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The genetic and epigenetic influences that establish and maintain the unique phenotype of the extraocular muscles (EOMs) are poorly understood. The vestibulo-ocular reflex (VOR) represents an important input into the EOMs, as it stabilizes eye position relative to the environment and provides a platform for function of all other eye movement systems. A role for vestibular cues in shaping EOM maturation was assessed in these studies using the ototoxic nitrile compound 3’,3’-iminodipropionitrile (IDPN) to eliminate the receptor hair cells that drive the vestibulo-ocular reflex. Intraperitoneal injections of IDPN were followed by a 2-week survival period, after which myosin heavy chain (MyHC) analysis of the EOMs was performed. When IDPN was administered to juvenile rats, the proportion of eye muscle fibers expressing developmental and fast myosins was increased, while EOM-specific MyHC mRNA levels were downregulated. By contrast, IDPN treatment in adult rats affected only the proportion of fibers expressing developmental MyHC isoforms, leaving the EOM-specific MyHC mRNA unaltered. These data provide evidence that the VOR modulates EOM-specific MyHC expression in development. The lack of significant changes in EOM-specific MyHC expression in adult EOM following IDPN administration suggests that there may be a critical period during development when alterations in vestibular activity have significant and permanent consequences for the eye muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051253
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  • 6
    Electronic Resource
    Electronic Resource
    Phagotrophic phytoflagellates in microbial food webs (1988)
    Springer
    Hydrobiologia 159 (1988), S. 89-97 
    Details
    ISSN: 1573-5117
    Keywords: phagotrophy ; myxotrophy ; mixotrophy ; selectivity ; cannibalism ; flocculation ; phagotrophic phytoflagellates ; heterotrophic microflagellates ; chrysophytes ; cryptophytes ; dinoflagellates ; Ochromonas ; Poterioochromonas ; Peridinium ; Cryptomonas ; Monas ; microbial food web ; metalimnetic plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phagotrophy by pigmented flagellates is known from the literature but has recently been rediscovered in the context of microbial food webs. Particle ingestion rates were found to be equivalent for pigmented and nonpigmented microflagellates in both field and laboratory studies. Ingestion rates of the chrysophytes Ochromonas danica, O. minuta, and Poterioochromonas malhamensis, the dinoflagellate Peridinium inconspicuum, and the cryptophytes Cryptomonas ovata and C. erosa were compared with those of two nonpigmented Monas species using 0.57 µm polystyrene beads as a food source. Ingestion rates were 0.31 to 3.17 beads/cell/h and filtration rates were 10−7 to 10−8 ml/cell/h with no detectable difference between pigmented and nonpigmented forms. Ingestion rates in unpigmented Monas species showed a linear increase with increasing particle concentration from 1.9 × 106 to 1.6 × 107 beads/ml. Light and DOC levels in the range of those encountered by phytoflagellates in the field also influenced laboratory measurements of bead ingestion by Poterioochromonas malhamensis. Ingestion rates decreased and photosynthesis increased over the natural PAR light range from 0 to 1800 microeinsteins/s/m2. At 40 microeinsteins/s/m2 maximum ingestion rates and high rates of photosynthesis occurred simultaneously. Ingestion rates decreased above 4 mgC/l supplied as glucose. DOC levels commonly occurring in Lake Oglethorpe range from 3.5 to 10.0 mgC/l. These studies suggest that mixotrophy, the trophic utilization of particulate food and dissolved organic matter as well as photosynthetically fixed organic matter, is a balanced process that can be regulated by environmental conditions. In field studies during a chrysophyte bloom, phytoflagellate grazing exceeded heterotrophic microflagellate grazing and constituted up to 55% of the bactivory of all microflagellates, ciliates, rotifers, and crustaceans combined. Neither bacterial abundance, light nor temperature were good predicters of grazing rates for the phagotrophic phytoflagellate association as a whole during this unstratified period. Phagotrophs are often most abundant at the metalimnetic plate during stratification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007370
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