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  • 1
    Digitale Medien
    Digitale Medien
    Transintegumentary absorption of acidic amino acids in the oligochaete annelid Enchytraeus albidus
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part A: Physiology 61 (1978), S. 55-60 
    Details
    ISSN: 0300-9629
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/0300-9629(78)90276-1
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  • 2
    Digitale Medien
    Digitale Medien
    Drepanilla limophila gen.n., sp.n. (Turbellaria, Dalyellioida) aus dem H2S-horizont des marinen sandluckensystems
    Amsterdam : Elsevier
    Zoologica Scripta 8 (1979), S. 19-24 
    Details
    ISSN: 0300-3256
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/0300-3256(79)90037-0
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  • 3
    Digitale Medien
    Digitale Medien
    Ultrastructure of the subepidermal musculature of Xenoturbella bocki, the adelphotaxon of the Bilateria (1997)
    Springer
    Zoomorphology 117 (1997), S. 71-79 
    Details
    ISSN: 1432-234X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Xenoturbella bocki is the only species of the high-ranked taxon Xenoturbellida. The species lives on marine mud bottoms at a depth of 20–120 m and moves extremely slowly by ciliary gliding. Nevertheless it possesses a well-developed body wall musculature with outer circular muscles, a prominent layer of inner longitudinal muscles and radial muscles that extend from the outer circular myocytes to the musculature surrounding the gastrodermis. The longitudinal myocytes are not compact cells, but form fascicles of fibrils running parallel to each other. Fine cytoplasmic cords connect the fibres of a cell to each other and with its nuclear region. The muscles are embedded within a sometimes expansive extracellular matrix (ECM) that lacks any fibrillar components. All muscle cells display conspicuous and numerous cytoplasmic extensions that are intermingled with each other. Tight coupling between adjacent cell membranes is not found, but zonula adhaerens-like junctions exist. Fibrils belonging to different myocytes, but also fibrils of the same cell, are coupled by such cytoplasmic extensions. Circular, radial and at least the peripheral longitudinal myocytes display cell-matrix connections with the internal lamina, a component of the subepidermal ECM. This internal lamina projects down into the centres of the fascicles with longitudinal muscle fibrils and forms extensive attachment zones with the muscle cells, reminiscent of focal contacts. For the ingestion of food, X. bocki opens the simple mouth pore and protrudes the aciliated gastrodermis. The body wall musculature is responsible for this protrusion and also for the withdrawal of the gastrodermis. In the past, possible phylogenetic kinships with the Acoelomorpha (Plathelminthes) or the Enteropneusta and Holothuroidea were discussed, but, on the basis of all information available, X. bocki is hypothesized to be the sister taxon of the Bilateria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004350050032
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  • 4
    Digitale Medien
    Digitale Medien
    Modified sperm ultrastructure and some data on spermiogenesis in Provortex tubiferus (Plathelminthes, Rhabdocoela): phylogenetic implications for the Dalyellioida (1995)
    Springer
    Zoomorphology 115 (1995), S. 41-49 
    Details
    ISSN: 1432-234X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Spermatozoa of Provortex tubiferus are thread-shaped, totally enclosed by peripheral microtubules and devoid of cilia or flagella. A peripheral layer of dense bodies underlies the cortical microtubules. Roundish mitochondria are arranged in a single row in the middle region of the sperm body. A special feature is documented in the appearance of a perinuclear condensation consisting of leaflet-like compartments. Such a perinuclear condensation is not known for any other species of the Plathelminthes. This characteristic may have functional roles in the locomotion and stabilization of the filiform aciliary spermatozoon. During spermiogenesis, two centrioles in a diplosome configuration differentiate near each nucleus of an early spermatid. With proceeding sperm maturation, a structure resembling an intercentriolar body is formed as typical for the taxon Trepaxonemata. However, axonemes are not differentiated and the intercentriolar body becomes disorganized. It is hypothesized that the Provorticinae (with Provortex) and the Graffillinae (with Paravortex) constitute a new monophylum with the autapomorphy “special type of aciliary spermatozoon”. The Provorticidae and the Graffillidae, respectively, are non-monophyletic groupings; the Kirgisellinae, Pseudograffillinae and Bresslauillinae do not belong to the monophylum Provorticinae + Graffillinae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00397933
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  • 5
    Digitale Medien
    Digitale Medien
    Heavy metal action on transintegumentary absorption of glycine in two annelid species (1979)
    Springer
    Marine biology 50 (1979), S. 175-179 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Absorption of 14C-glycine from ambient sea water across the body surface of the oligochaete Enchytraeus albidus Henle was, after 6 h preincubation, significantly reduced in the presence of 0.1 to 0.15 ppm mercury, 0.25 ppm copper, 1.5 ppm silver, and 2 ppm cadmium. Addition of heavy metal salts reduced maximum uptake rates (V max ), without affecting transport constants (K t ). Influx of 14C-glycine remained unchanged in the presence of up to 10 ppm aluminium, chromium, iron, lead, molybdenum, vanadium, and zinc. Effects of up to 150 ppm nickel, manganese, cobalt and selenium were negligible. Inhibition of glycine absorption by mercury and cadmium in the polychaete Nereis diversicolor Müller is almost identical with results presented for E. albidus. Transintegumentary solute absorption in soft-bodied marine invertebrates obviously represents a suitable biological function for studies on heavy metal toxicity. The close relationship between rates of heavy metal absorption, inhibition of transintegumentary glycine uptake, and acute toxicity is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00397824
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  • 6
    Digitale Medien
    Digitale Medien
    Cloning of the coat protein gene from beet necrotic yellow vein virus and its expression in sugar beet hairy roots (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 777-782 
    Details
    ISSN: 1432-2242
    Schlagwort(e): BNYVV ; Coat protein ; Hairy roots ; Plant virus resistance ; Sugar beet
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Expression of the beet necrotic yellow vein virus (BNYVV) coat protein (CP) gene in transgenic sugar beet hairy roots was accomplished as a step towards CP-mediated virus resistance. A cDNA for the CP gene and its 5′ terminal untranslated leader sequence was prepared from BNYVV RNA, using two oligodeoxynucleotides to prime the synthesis of both strands. Second-strand synthesis and amplification of the cDNA were done by Taq DNA polymerase chain reactions. Run-off transcripts of the cloned cDNA sequence were obtained and translated in vitro, yielding immunoreactive CP. A binary vector construction containing the CP gene under the control of the 35S promoter of cauliflower mosaic virus was prepared and used for Agrobacterium rhizogenes-mediated transformation of sugar beet tissue. Stable integration and expression of the CP gene in sugar beet hairy roots was demonstrated by Southern, Northern, and Western blot analysis, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224989
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  • 7
    Digitale Medien
    Digitale Medien
    First record of a free-living dalyellioid turbellarian from the pacific:Balgetia pacifica nov. spec. (1979)
    Springer
    Helgoland marine research 32 (1979), S. 359-364 
    Details
    ISSN: 1438-3888
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Balgetia pacifica nov. spec. from coarse sand beaches along the west coast of San Juan Island (Washington) is described and its taxonomy discussed. The species is characterized by its large bursal apparatus with a strengthened copulatory bursa.B. pacifica is the first free-living species of the Turbellaria Dalyellioida recorded from the Pacific Ocean.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02189590
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  • 8
    Digitale Medien
    Digitale Medien
    Syncytial organization of acanthors of Polymorphus minutus (Palaeacanthocephala), Neoechinorhynchusrutili (Eoacanthocephala), and Moniliformis moniliformis (Archiacanthocephala) (Acanthocephala) (1997)
    Springer
    Parasitology research 83 (1997), S. 326-338 
    Details
    ISSN: 1432-1955
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The fine structures of immature and of developed shelled acanthors of three species belonging to the three subgroups of the Acanthocephala were investigated. Acanthors are surrounded by four eggshells (embryonic envelopes) and are composed of three syncytia: a frontal syncytium, a central syncytium, and an epidermal syncytium. Neither a sense organ nor a nervous system has been found. The central syncytium shows a mass of condensed nuclei and 12 decondensed nuclei and gives rise to 10 anterior/posterior subepidermal myofibrillar systems and 2 oblique retractor muscles. Circular muscles are missing. A single decondensed nucleus can be assigned to each of the 12 muscular systems. The epidermal syncytium embeds the other two syncytia and forms the wrinkled epidermis, which shows an extracellular glycocalyx and intrasyncytial condensations. Prominent recurved hooks, which mark the anterior end of each acanthor, and body spines are intraepidermal differentiations. Partly branched tubular infoldings of the epidermal plasma membrane of the acanthor exist and represent precursors of the pore ducts typical of the adult epidermis. Autapomorphies in the ground pattern of the monophylum Acanthocephala are the four eggshells, the early development of three syncytia, the condensed nuclei in the central syncytium, and the differentiation of ten longitudinal muscle bands and two muscle retractors and of intraepidermal hooks and spines. The syncytial organization of the epidermis with intraepidermal skeletal condensations and infoldings of the apical plasma membrane are characteristics inherited from a stem species common to Acanthocephala, Seison, and Rotifera.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004360050257
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  • 9
    Digitale Medien
    Digitale Medien
    Early calcification patterns of the iliac arteries and their relation to the arterial structure (1972)
    Springer
    Cell & tissue research 130 (1972), S. 378-388 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Arteries ; Children ; Structure ; Pattern of calcification ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Gross calcifications of the common iliac and internal iliac arteries represent a common finding in newborn children and infants. In both arteries, the calcific deposits regularly appear in certain areas of the arterial luminal surface only, whereas the other parts of the arterial wall remain free of gross lesions even in cases with a pronounced calcification. In the common iliac artery, the lateral wall of the vessel and the adjacent sectors of the anterior and posterior wall represent the predilection site of calcific deposits. In the internal iliac artery, the gross calcifications have been regularly demonstrated in the dorso-medial wall. The predominant localisation of the calcification in these parts of the vessels and its absence in the others depend on the definite structural features of the arterial tube and different affinity for calcium of the individual structural elements. In both iliac arteries, only the primary internal elastic membrane undergoes early calcification. However, unlike the most muscular arteries, this membrane is not developed in the whole arterial circumference of the common iliac and internal iliac arteries, but is absent in large areas of their arterial luminal layer. In these areas, the subendothelial or subintimal elastic layers are formed by the networks of longitudinally arranged elastic fibers or membraneous elastic structures which arise from the elastic networks with the further growth. These elastic elements always stay free of calcific deposits. The structural features found in both iliac arteries may be important for the development of the later pathological changes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306950
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