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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 266 (1991), S. 585-590 
    ISSN: 1432-0878
    Keywords: Hepatopancreas ; Tubular structures ; Endoplasmic reticulum, smooth ; Lanthanum ; Tannic acid ; Palaemonetes zariquieyi (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural studies of the hepatopancreatic R-cells of Palaemonetes zariquieyi revealed a basal tubular network. Tannic acid and lanthanum nitrate techniques established the presence of numerous infoldings of the basal and lateral plasma membranes that constitute the tubular system. Lipoprotein-like particles were detected inside this system. The contrast of these particles was increased by the osmium-thiocarbohydrazide-osmium (OTO) method. The ultrastructure of the membranous tubular system displays several morphological variants: (a) the tubular membranous system is curved and branched, with a regular reticular aspects, and is often associated with smooth endoplasmic reticulum (SER); (b) the basal and lateral plasma membranes exhibit shallow invaginations that are curved, and (c) the invaginations of the plasma membrane form a membranous branching system with a similar morphology to that of the SER. The possible intervention of the membranous tubular system in exchange processes with the haemolymph is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Defence mechanisms ; Encapsulation ; Granulocytes ; Immunocytochemistry ; Parasitism ; Perkinsus sp. (Protozoa) ; Tapes semidecussatus (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Parasitosis by the trophozoite protozoan Perkinsus sp. (Apicomplexa, Perkinsea) induces in the gill filaments of the clam Tapes semidecussatus (Mollusca, Bivalvia) a cellular reaction, which is constituted by infiltrated granulocytes. This cellular reaction has characteristics of those of a holocrine gland, since the parasites are encapsulated by the secretion product of the granulocytes after cell death. An enriched fraction of prezoosporangia and their associated capsule was obtained after culture of the parasitized gills in fluid thioglycollate medium. Specific polypeptides from this fraction were separated by SDS-PAGE and isolated for rabbit immunizations. The serum obtained against an Mr 225 kDa polypeptide, revealed its exclusive localization in the capsule and in the granules of the infiltrated granulocytes, thus indicating that this polypeptide is synthesized by these cells and secreted, in a polarized way, around the trophozoites resulting in their encapsulation. Selective deglycosylation of the polypeptide, by Endo H and alkaline β-elimination, did not show an effect on its molecular weight or antibody recognition. Furthermore, the absence of the 225 kDa band in the Western-blots of non-parasitized gills indicated the specific association of this polypeptide with the parasitosis. Finally, this is the first tissue-specific factor described in molluscs in relation to defence mechanisms.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Key words: Defence mechanisms ; Encapsulation ; Granulocytes ; Lectin cytochemistry ; Parasitism ; Perkinsus sp. (Protozoa) ; Tapes semidecussatus (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The cellular defence mechanism of the clam Tapes semidecussatus (Mollusca, Bivalvia) against infection by the parasite protozoan Perkinsus sp. (Apicomplexa, Perkinsea) was studied in the gill filaments. The parasites, localized in the connective tissue, induced a cellular reaction involving infiltrated granulocytes. These showed a secretory aspect, with the cytoplasm being filled by membrane-bound granules with internal membranes. The holocrine secretion, which was proteic and slightly glycosylated, by the granulocytes gave rise to the encapsulation of the parasites. After incubation with lectins from Canavalia ensiformis, Triticum vulgaris, Helix pomatia, Glycine max, Arachis hypogaea, Ricinus communis (agglutinin), Ulex europeus I and Limax flavus, a lack of specific and/or main sugars was observed in the plasma membrane of parasite and granulocyte, and in the wall of the former. Furthermore, GalNacα1,3GalNac and β-d-gal residues were only detected in association with the internal membranes and dense regions of both granules and capsule, respectively. Blood granulocytes were observed at the periphery of the cellular reaction, close to blood vessels, and these appeared to re-differentiate to give the granulocytes of the cellular reaction. The data reported here suggest that this parasite induces the infiltration and re-differentiation of specialized cells in the host mollusc. In addition, a polarized secretion of a specific defence product is described for the first time.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Key words: Defence mechanisms ; Encapsulation ; Granulocytes ; Immunocytochemistry ; Parasitism ; Perkinsus sp. (Protozoa) ; Tapes semidecussatus (Mollusca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Parasitosis by the trophozoite protozoan Perkinsus sp. (Apicomplexa, Perkinsea) induces in the gill filaments of the clam Tapes semidecussatus (Mollusca, Bivalvia) a cellular reaction, which is constituted by infiltrated granulocytes. This cellular reaction has characteristics of those of a holocrine gland, since the parasites are encapsulated by the secretion product of the granulocytes after cell death. An enriched fraction of prezoosporangia and their ass ociated capsule was obtained after culture of the parasitized gills in fluid thioglycollate medium. Specific polypeptides from this fraction were separated by SDS-PAGE and isolated for rabbit immunizations. The serum obtained against an Mr 225 kDa polypeptide, revealed its exclusive localization in the capsule and in the granules of the infiltrated granulocytes, thus indicating that this polypeptide is synthesized by these cells and secreted, in a polarized way, around the trophozoites resulting in t heir encapsulation. Selective deglycosylation of the polypeptide, by Endo H and alkaline β-elimination, did not show an effect on its molecular weight or antibody recognition. Furthermore, the absence of the 225 kDa band in the Western-blots of non-parasitized gills indicated the specific association of this polypeptide with the parasitosis. Finally, this is the first tissue-specific factor described in molluscs in relation to defence mechanisms.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0878
    Keywords: Defence mechanisms ; Encapsulation ; Granulocytes ; Lectin cytochemistry ; Parasitism ; Perkinsus sp. (Protozoa) ; Tapes semidecussatus (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The cellular defence mechanism of the clam Tapes semidecussatus (Mollusca, Bivalvia) against infection by the parasite protozoan Perkinsus sp. (Apicomplexa, Perkinsea) was studied in the gill filaments. The parasites, localized in the connective tissue, induced a cellular reaction involving infiltrated granulocytes. These showed a secretory aspect, with the cytoplasm being filled by membrane-bound granules with internal membranes. The holocrine secretion, which was proteic and slightly glycosylated, by the granulocytes gave rise to the encapsulation of the parasites. After incubation with lectins from Canavalia ensiformis, Triticum vulgaris, Helix pomatia, Glycine max, Arachis hypogaea, Ricinus communis (agglutinin), Ulex europeus I and Limax flavus, a lack of specific and/or main sugars was observed in the plasma membrane of parasite and granulocyte, and in the wall of the former. Furthermore, GalNacα1,3GalNac and β-d-gal residues were only detected in association with the internal membranes and dense regions of both granules and capsule, respectively. Blood granulocytes were observed at the periphery of the cellular reaction, close to blood vessels, and these appeared to re-differentiate to give the granulocytes of the cellular reaction. The data reported here suggest that this parasite induces the infiltration and re-differentiation of specialized cells in the host mollusc. In addition, a polarized secretion of a specific defence product is described for the first time.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Of mussels taken from the Ebro Delta River (E. Spain), 3% have a nonmodified copepod, Modiolicola gracilis, in the gill tissues. The cuticle of different segments of the body has an epicuticle with two layers, which show external microvilli-like projections. Weakly positive reactivity to the PTA technique has been detected in the external region. The procuticle has the helicoidal architecture of the chitinous tegument in arthropods, whereas the cuticle shows discontinuities in the regions of ducts in tegumental glands.The integument is comprised of three types of cells. Epidermal cells are flat with numerous mitochondria. Muscle cells show well-developed mitochondria with several longitudinally distributed cristae. A third and secretory cell shows a well-developed rough endoplasmic reticulum and Golgi complex in the basal zone. Its apical portion is full of secretory granules. Through the cuticle, these integumental glands open directly to the cuticular surface via a short duct coated by epicuticle.The composition and specializations of this complex cuticular architecture differ markedly from those shown by an endoparasitic copepod detected in the digestive gland of the mussel. It does not appear that the specializations detected in the cuticle of M. gracilis lead to any histopathological alteration in host tissues. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 221 (1994), S. 199-210 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations on sperm maturation in the hamster (Mesocricetus auratus) epididymis revealed that the cytoplasmic droplet migrates from the proximal position of the sperm flagellum to the end of the midpiece. This process begins in the testis or vas efferens and ends in the cauda region of the epididymis. A study of different regions of the epididymis and vas deferens demonstrated that the cytoplasmic droplet is not released from the sperm into the luminal fluid. An ultrastructural study of the cytoplasmic droplet demonstrated changes in its morphology as its position moved distally along the midpiece. Membranous components called saccules or vesicles, believed to be remnants of the Golgi apparatus present in the cytoplasmic droplet, changed their morphology during the migration process. Inclusion bodies within vesicles were released to the lumen at the levels of the cauda epididymis and the vas deferens. © 1994 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
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  • 8
    Publication Date: 2021-07-23
    Description: There is currently relatively little information on how marine organisms process and analyze sound, making assessments about the impacts of artificial sound sources in the marine environment difficult. However, such assessments have become a priority because noise is now considered as a source of pollution that increasingly affects the natural balance of marine ecosystems. We present the first morphological and ultrastructural evidence of massive acoustic trauma, not compatible with life, in four cephalopod species subjected to low-frequency controlled-exposure experiments. Exposure to low-frequency sounds resulted in permanent and substantial alterations of the sensory hair cells of the statocysts, the structures responsible for the animals' sense of balance and position. These results indicate a need for further environmental regulation of human activities that introduce high-intensity, low-frequency sounds in the world's oceans.
    Type: Article , PeerReviewed
    Format: text
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