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  • 1
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of device attachment on parental activities and body mass change in instrumented birds and their mates, and on chick growth and survival, were studied in Adélie Penguins Pygoscelis adeliae in Lützow-Holm Bay, Antarclica. Penguins on which small devices were fitted with rubber band harnesses exhibited increased foraging trip duration, and decreased body mass, food delivery rate, chick growth and chick survival. Their mates did not increase food delivery rate. Those on which small or large devices were fitted with epoxy glue did not change foraging trip duration, body mass, or chick survival. However, large devices decreased chick growth. These effects were more obvious; among penguins fitted with devices later in the chick rearing period, and suggest that: 1) parents fitted with devices give a priority to maintenance of their own energy reserve over guarding and food delivery for chicks; and, 2) parents' decreasing energy reserves later in the breeding season might intensify the effects of devices.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adélie penguins Pygoscelis adeliae in Enderby Land, Antarctica feed mainly on Euphausia superba during the chick rearing season in shelf areas where fast sea-ice remains: indicating that E. superba is abundant under the fast sea-ice in these areas. The shelf areas in Enderby Land, therefore, are unique since the previous studies of Adélie penguin diet in Ross Sea, Adélie Land and Prydz Bay show that E. crystallorophias is the most abundant krill species in shelf areas in general.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-5604
    Keywords: pure osteoclasts ; collagen gel ; dentine-resorbing activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract When unfractionated rabbit bone cells were seeded and incubated on a collagen gel, tartrate-resistant acid phosphatase (TRAP)-positive multinucleate cells (MNCs) adhered to the surface of the collagen gel more readily than other types of cells. Based on the differences in adherence of the MNCs onto the collagen gel, we developed a new method for the isolation of functionally mature osteoclasts with high purity. Sequential treatments with pronase E/EDTA and collagenase at a low concentration (0.01%) released most of the nonosteoclasts from the gel surface, whereas only MNCs still remained on the surface. After washing off the released cells, we could harvest a cell population highly enriched for osteoclasts from the collagen gel by a second digestion with collagenase. The yield of TRAP-positive MNCs was 40000–50000 cells per long bones from one rabbit. The purity of the TRAP-positive MNCs was reproducibly more than 95%. These cells, cultured on dentine slices, showed typical ultrastructural features of osteoclasts, i.e., a highly developed ruffled border and clear zone, and they excavated the dentine to form pits. In addition, the isolated MNCs showed specific binding to calcitonin. The dentine-resorbing activity appeared as early as 2h after plating and reached a plateau at 24h. The pit area increased in direct proportion to the number of osteoclasts plated. Calcitonin inhibited the dentine-resorbing activity, but parathyroid hormone or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] did not have any effect on it. Though these cells exhibited dentine-resorbing activity even in the absence of any support from stromal cells, this activity was enhanced by rabbit stromal cells in response to 1,25(OH)2D3. In addition, these stromal cells elongated the life span of the isolated osteoclasts without 1,25(OH)2D3. To assess the functions of authentic osteoclasts, we can now culture highly purified and functional osteoclasts under the desired conditions and in controlled cell numbers. This isolation method is also applicable to numerous molecular studies.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Osteoclast formation from hemopoietic precursors has been shown to require the support of stromal cells in bone tissue. In this study, we demonstrated that hepatocyte growth factor (HGF) is one of the stromal cell-derived molecules responsible for osteoclast-like cell formation. For our experimens, we used a coculture system for osteoclastic cell formation and activation in which hemopoietic blast cells are cocultured with calvaria-derived stromal MC3T3-G2/PA6 (PA6) cells on dentine slices in the presence of 1, 25-dihydroxyvitamin D3 [1,25(OH)2D3]. Addition of anti-HGF neutralizing IgG to the cocultures inhibited the formation of osteoclastic cells and their dentine-recorbing activity. We detected a single 6.0-kb transcript for HGF in PA6 cells, and also recognized immunoreactive Mr. 81,000 and 88,000 forms of HGF in conditioned medium (CM) from PA6 cell cultures, the level of which reached 6 ng/ml. Both the CM and HGF stimulated the proliferation of blast cells synergistically with granulocyte-macrophage colony-stimulating factor, resulting in an increased number of osteoclast precursors that respond to 1,25(OH)2D3 that are tartrate-resistant acid phosphatase-positive multinucleate cells in stromal cell-free blast cell cultures in plastic wells. The effect of the CM was diminished by the addition of anti-HGF IgG. However, neither the CM nor HGF stimulated the formation of osteoclastic cells and pits on dentine slices in the absence of PA6 cells. These results suggest that although HGF cannot completely replace stromal cells, it is one of the paracrine mediators produced by stromal cells that act on proliferation of osteoclastic cell precursors. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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