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  • 1
    Electronic Resource
    Electronic Resource
    Fine structure of the protonephridial system in planaria (1968)
    Springer
    Cell & tissue research 92 (1968), S. 509-523 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The flame cells of common fresh-water planarians are cyrtocytes similar in basic structure and function to the protonephridial end-organs in other phyla. They function as ultrafilters for intercellular fluid and are shaped like an elongate basket containing the ciliary flame. Thin regions of the basket wall are fenestrated by groups of parallel slits. The slits are 350 Å wide and (viewed en face) appear to be bridged by 55 Å filaments spaced at 200 Å intervals. Under varied conditions of fixation, these filaments are most similar to the filaments associated with the glycocalyx coating the luminal surface of the cell. The possible involvement of the preserved elements with the “filtration membrane” is discussed. Thicker cytoplasmic columns or ribs containing 220 Å diameter microtubules support the thin regions of the basket wall and are the base for radial processes which prevent adjacent cells from occluding the fenestrae. Rapidly cooling the worm from room temperature to 2°C results in a short term reduction in the number of microtubules seen in the basket ribs. However this number has returned to normal after one minute in the cold, and by five minutes a greaterthan-normal number of microtubules is present which has been confirmed to be present after 3 days at 2°C. If microtubule subunits are hydrophobically bonded, these results suggest a metazoan control of such bonding which has not yet been demonstrated for protozoans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336662
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  • 2
    Electronic Resource
    Electronic Resource
    Fine structure of the protonephridial system in planaria (1968)
    Springer
    Cell & tissue research 92 (1968), S. 524-535 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distal to the flame cells, the protonephridial tubules of fresh-water planarians are circumferentially composed of at least two cells attached by septate junctions; and may be divided, on the basis of morphological criteria, into three longitudinal regions. The cells of nonciliated ductules and ciliated collecting ducts appear to be absorbing material from the lumen; and a distinct proximal-distal polarity is present in each individual cell. At the proximal pole are concentrated micropinocytotic caveolae with amorphous and structural coats on the luminal and cytoplasmic surfaces, respectively. Proceeding distally, a Golgi complex is situated between the micropinocytotic vesicles and large, basophilic, paracrystaline granules. This unusual polarity is interpreted to be important to the resorptive function of the cells. In four areas of the worm, the branched collecting ducts combine to form single osmoregulatory (O. R.) ducts. The O. R. cells have many mitochondria located in slender processes formed by basal and lateral invaginations and interdigitations. The adjacent plasmalemmas of normally fixed cells are separated by a 180 Å gap; but higher tonicity fixative shrinks the cells, increasing the apparent extracellular space. The O. R. cells differ from analogous cells in higher animals in their function as an osmoregulatory epithelium in the absence of a basement membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336663
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  • 3
    Electronic Resource
    Electronic Resource
    Contractile vacuoles in cells of a fresh water sponge, Spongilla lacustris (1978)
    Springer
    Cell & tissue research 192 (1978), S. 309-317 
    Details
    ISSN: 1432-0878
    Keywords: Contractile vacuole ; Water balance ; Invertebrate ; Membranes ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Forty or more independently functioning contractile vacuoles (CVs) occupy the central region of fresh water sponge pinacocytes. Each CV undergoes a cycle of enlargement by fusion, movement, shape change, rounding up, and emptying over the course of 5–30 min. Diameter at discharge varies between 1 and 13 μm. CVs in all cell types are associated with submicroscopic coated vesicles. Filled CVs are bounded by an unmodified trilaminar membrane, but vacuoles with excess membrane frequently show coated evaginations. These evaginations are thought to pinch off as coated vesicles, providing an avenue for membrane recycling in the CV system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220748
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  • 4
    Electronic Resource
    Electronic Resource
    Lipocortin 1 in apoptosis: Mammary regression (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 1-10 
    Details
    ISSN: 0003-276X
    Keywords: Annexin ; Cell Death ; Calcium ; Phosphatidylserine ; Transglutaminase ; EGF ; Inflammation ; Rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Enigmatically, degradation of debris generated in programmed cell death (apoptosis) elicits little inflammation. Having previously detected the upregulation of lipocortin 1 (LC1), a 35-kDa protein with anti-inflammatory and immuno-suppressive properties, at sites of non-inflammatory phagocytosis in the central nervous system (J Neurosci Res 36:491-500, 1993), we sought to determine if LC1 was involved in apoptosis.Methods: LC1 immunoreactivity in mammary glands of adult rats was quantified in situ using video microdensitometry before and during postlactational regression.Results: LC1 is present in the mammary ducts but is absent from the alveoli during lactation. One day after weaning, however, LC1 is detected in the lactiferous cells and, as apoptosis proceeds over the ensuing 4 days, total LC1 in the gland increases 〉10-fold over resting levels. LC1 remains high in both the apoptotic cells and epithelial phagocytes through day 10, but the total LC1 per gland drops as the apoptotic cells are cleared.Conclusions: Published experiments have shown that LC1 specifically binds Ca++ and phosphatidylserine, and that these affinities are modulated by tyrosine phosphorylation and cross-linking with transglutaminase. Thus, LC1 appears to be a candidate for several putative activities in apoptosis (e.g., phagocyte recognition via phosphatidylserine binding and/or buffering intracellular Ca++) in addition to its anti-inflammatory role. © 1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092420102
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  • 5
    Electronic Resource
    Electronic Resource
    Optic chiasm and infundibular decussation sites in the developing rat diencephalon are defined by Glial Raphes expressing p35 (Lipocortin 1, Annexin I) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 195 (1992), S. 75-86 
    Details
    ISSN: 0002-9106
    Keywords: Lipocortin 1 ; Annexin I ; Optic chiasm ; Pituitary ; Diencephalon ; Embryology ; Astrocyte ; Radial glia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: p35, a Ca++-phospholipid-binding protein that serves as a substrate for the EGF receptor tyrosine kinase, is expressed by primitive glial ependymal cells to define a raphe occupying the ventral midline in the spinal cord and hindbrain of rat embryos (McKanna and Cohen, Science 243:1477-1479, 1989). p35 appears transiently in the median one-third (80 μ) of the floor plate at precisely the time and place where axons cross to form the ventral commissure. We postulated that if p35 is involved with commissure development, homologous p35 raphes might be found at decussation sites rostral to the floor plate, including the optic chiasm. The present report describes two developmentally regulated p35 raphes in the diencephalon. One raphe is present for 2-3 days at the rostral lip of the nascent infundibulum, the reported decussation site of axons running from the supraoptic nucleus to the neurohypophysis; the other raphe appears in the rostral two-thirds of the optic chiasm, the site traversed by the optic axons. p35 is never expressed in the caudal one-third of the chiasm that accommodates non-retinal axons. To the best of our knowledge, this is the first identification of a specific marker for the retinal component of the optic chiasm. Because the p35 is gone by embryonic day 18.5, it is absent during final stages of chiasm formation when axons from the temporal retina decussate. Thus, p35 also may contribute to the “barrier” perceived by fibers that remain ipsilateral. Our data suggest that the p35 raphe contributes to the midline's role in commisure morphogenesis. Putative lipocortin activities including regulating PLA2, eicosanoids, or intracellular Ca++ could be involved in altering cue specificity as decussating axon growth cones traverse the p35 compartment. © 1992 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001950202
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  • 6
    Electronic Resource
    Electronic Resource
    Localization of p35 (annexin I, lipocortin I) in normal adult rat kidney and during recovery from ischemia (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 153 (1992), S. 467-476 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 35-kDa protein (p35, lipocortin I, annexin I), originally discovered as a Ca++-dependent substrate for the EGF receptor tyrosine kinase, binds Ca++ and phospholipids, is developmentally regulated in embryos and has restricted expression in adults. Immunohistochemistry of normal rat kidney shows that p35 is enriched in epithelia of Bowman's capsule, the macula densa, and medullary/papillary collecting ducts, suggesting that p35 is related to specialized renal functions. Light staining is observed in the thick ascending limb; elsewhere, immunoreactivity is nil. Since renal recovery from ischemia involves both hyperplasia and hypertrophy and reportedly is accelerated by EGF, we examined p35 distribution during this process. After 48 hours of recovery, both the distribution and amount of renal p35 are altered. Immunoblots show p35 levels increased at least threefold in whole-kidney homogenates. The expression of p35 is still highly restricted in recovering kidneys; however, the thick ascending limb now stains heavily. This is the first documentation of alterations in annexin levels during a pathophysiologic response. However, our attempts to discern effects of exogenous EGF on the recovery from ischemia were negative for both mitotic index and renal function assays. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041530305
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