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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of the y-organs of Cancer antennarius in normal and de-eyestalked crabs (1980)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 163 (1980), S. 167-174 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paired Y-organs of crustaceans control the molting process. In males of C. antennarius, these glands are opalescent, lobulated, epithelioid structures embedded in brown fatty tissue. Cells in the periphery extend processes to the connective tissue capsule, an arrangement that suggests increased surface area for metabolic exchange. The processes contain mitochondria and are tipped distally with electron dense material. The cytoplasm, scarce relative to nuclear volume, contains vesicles, polymorphic mitochondria with tubular cristae, and numerous free ribosomes, but little in way of smooth or rough endoplasmic reticulum or Golgi complexes. Progressing from intermolt to the premolt stage, mitochondria, as well as vesicles, and electron-dense particles in peripheral processes increase somewhat in number. Also, heterochromatin masses concentrate adjacent to the nuclear envelope. Eyestalk removal, which induces premolt stages in some species, did not produce consistent change in Y-organ substructure in C. antennarius. Although evidence is accumulating that Y-organs secrete a steroid molting hormone during late intermolt-premolt, the substructure of the glands exhibits neither (a) striking changes with the molt cycle, nor (b) all the characteristics typical of vertebrate steroid hormone synthesizing glands. Nevertheless, the structural features, respectively, are consistent with biochemical evidence that Y-organs (a) rapidly take up and convert sterol precursor and secrete a product without its accumulation or change in total sterol pool size, and (b) apparently cannot synthesize the sterol precursor. Y-organ cytology closely resembles that of some vertebrate steroid hormone secreting glands in which this synthetic capacity is minimal.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051630205
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  • 2
    Electronic Resource
    Electronic Resource
    Testosterone regulation of pigmentation in scrotal epidermis of the rat (1973)
    Springer
    Cell & tissue research 140 (1973), S. 451-458 
    Details
    ISSN: 1432-0878
    Keywords: Epidermis ; Scrotum ; Melanocytes ; Testosterone ; Tyrosinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of testosterone on melanocyte number, morphology, melanin content and tyrosinase activity were studied in epidermis from several body regions of the black-pelted Long-Evans rat. Determinations were made in epidermal sheets processed for histochemical analysis by incubation in the presence of the melanin precursor, 3,4-dihydroxyphenylalanine (DOPA). Melanin content, cell volume, dendritic branching and tyrosinase activity of scrotal epidermal melanocytes all decreased progressively with time following castration. Daily testosterone injection, begun 14 days after castration, increased tyrosinase activity in 4 days, and dendritic branching in 6 days, of treatment; melanin content, cell volume and enzyme activity were restored to normal intact levels within 14 days of treatment, at which time newly synthesized melanin was evident in keratinocytes. The total number of scrotal epidermal melanocytes was not changed by castration or testosterone administration. Neither castration nor testosterone replacement affected any parameter of epidermal melanocytes in preputial, perianal or eyelid skin which, together with the scrotum, are the animals' only pigmented areas. Androgen control of epidermal pigmentation in the male rat is therefore specific for the scrotum and is manifested through regulation of melanin synthesis in stable populations of melanocytes rather than through increases in numbers of melanocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306672
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  • 3
    Electronic Resource
    Electronic Resource
    Uptake of high-density lipoprotein by Y-organs of the crab, cancer antennarius. II. formal characterization of receptor-mediation with isolated membranes (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 77-91 
    Details
    ISSN: 0739-4462
    Keywords: Cancer antennarius ; cholesterol ; ecdysteroids ; high-density lipoproteins ; receptors ; Y-organs ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Y-organs are the ecdysial glands of crustaceans, responsible for synthesis and secretion of ecdysteroid hormones. For this purpose, the glands acquire cholesterol as obligate precursor entirely from circulating high-density lipoprotein (HDL). A preceding study provided evidence for the mechanism of acquisition: Y-organs take up cholesterol bound to HDL by an energy-requiring process, receptor-mediated absorptive endocytosis. The present study characterized the receptors involved utilizing isolated Y-organ membranes. HDL binding was saturable and specific; a dissociation constant (Kd) of 1.08 × 10-7 M and a binding maximum at equilibrium (Bmax) of 70 μg HDL protein/mg membrane protein, were obtained. Binding was decreased by protease and was dependent upon calcium. Y-organs are regulated negatively by a peptide hormone from the eystalks, molt-inhibiting hormone (MIH). Y-organ membranes from de-eyestalked crabs (MIH absent) exhibited the same Kd value as membranes from intact crabs, but a Bmax 17% higher. Thus, MIH activity apparently does not change the binding affinity of HDL, but decreases the number of binding sites. These results agree with our previous findings that MIH depresses ecdysteroid synthesis in part by inhibiting cholesterol uptake. Generally, Y-organ cells appear to contain receptors for HDL that are of high affinity and high binding capacity, similar to the characteristics reported for the binding of insect HDL (vitellogenin) to fat bodies and oocytes. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940300106
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  • 4
    Electronic Resource
    Electronic Resource
    Uptake of high-density lipoprotein by Y-organs of the crab, Cancer antennarius. I. characterization in vitro and effects of stimulators and inhibitors (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 61-75 
    Details
    ISSN: 0739-4462
    Keywords: Cancer antennarius ; cholesterol ; crabs ; ecdysteroids ; high-density lipoproteins ; Y-organs ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cholesterol is the obligate precursor for ecdysteroid hormone synthesis by the ecdysial glands (Y-organs) in crustaceans, and all cholesterol in the hemolymph is bound to high-density lipoprotein (HDL). The mechanism was studied of how Y-organ cells acquire cholesterol. Y-organ segments were incubated with HDL isolated from hemolymph and labeled with 125I. After incubation, tissue was homogenized in acid to determine radioactivity in acid-precipitable (cell associated, intact) HDL and in acid-soluble (degraded) HDL. Both HDL uptake and degradation showed saturation kinetics. At saturation most of the total counts represented degraded HDL; by 3 h, degradation was 80%. Rates of HDL uptake and breakdown were higher in Y-organs from de-eyestalked crabs (deprived thereby of molt-inhibiting hormone, MIH) than in glands from intact crabs. Both parameters were depressed by inhibitors of glycolysis and oxidative phosphorylation dose dependently and by low temperature. HDL uptake also was depressed by cAMP added to the medium experimentally or through efflux from the tissue during incubation. These results indicate a mechanism for HDL uptake that entails receptor-mediated, energy-dependent endocytosis of the entire HDL-cholesterol complex. Also the results suggest that HDL uptake and degradation are mediated by cAMP and depressed by an eyestalk factor, presumably MIH. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940300105
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