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  • HU Berlin  (5)
  • UB Potsdam
  • Berlin VÖBB/ZLB
  • Jüdisches Museum
  • Kammergericht
  • Akad. der Künste
  • Kreis- und Fahrbibliothek Lübben
  • Le, Mai-Lee Van  (5)
  • Open access  (5)
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  • HU Berlin  (5)
  • UB Potsdam
  • Berlin VÖBB/ZLB
  • Jüdisches Museum
  • Kammergericht
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  • Open access  (5)
  • 1
    UID:
    edochu_18452_24225
    Format: 1 Online-Ressource (15 Seiten)
    Content: While cellulose is the most abundant macromolecule in the biosphere, most animals are unable to produce cellulose with the exception of tunicates. Some tunicates have evolved the ability to secrete a complex house containing cellulosic fibers, yet little is known about the early stages of the house building process. Here, we investigate the rudimentary house of Oikopleura dioica for the first time using complementary light and electron microscopic techniques. In addition, we digitally modeled the arrangement of chambers, nets, and filters of the functional, expanded house in three dimensions based on life-video-imaging. Combining 3D-reconstructions based on serial histological semithin-sections, confocal laser scanning microscopy, transmission electron microscopy, scanning electron microscopy (SEM), and focused ion beam (FIB)-SEM, we were able to elucidate the arrangement of structural components, including cellulosic fibers, of the rudimentary house with a focus on the food concentration filter. We developed a model for the arrangement of folded structures in the house rudiment and show it is a precisely preformed structure with identifiable components intricately correlated with specific cells. Moreover, we demonstrate that structural details of the apical surfaces of Nasse cells provide the exact locations and shapes to produce the fibers of the house and interact among each other, with Giant Fol cells, and with the fibers to arrange them in the precise positions necessary for expansion of the house rudiment into the functional state. The presented data and hypotheses advance our knowledge about the interrelation of structure and function on different biological levels and prompt investigations into this astonishing biological object.
    Content: Peer Reviewed
    In: Malden, Mass. [u.a.] : Wiley, 282,8, Seiten 1259-1273
    Language: English
    URL: Volltext  (kostenfrei)
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  • 2
    UID:
    edochu_18452_27800
    Format: 1 Online-Ressource (14 Seiten)
    ISSN: 0362-2525 , 1097-4687 , 0362-2525 , 1097-4687
    Content: Appendicularia comprises 70 marine, invertebrate, chordate species. Appendicularians play important ecological and evolutionary roles, yet their morphological disparity remains understudied. Most appendicularians are small, develop rapidly, and with a stereotyped cell lineage, leading to the hypothesis that Appendicularia derived progenetically from an ascidian-like ancestor. Here, we describe the detailed anatomy of the central nervous system of Bathochordaeus stygius, a giant appendicularian from the mesopelagic. We show that the brain consists of a forebrain with on average smaller and more uniform cells and a hindbrain, in which cell shapes and sizes vary to a greater extent. Cell count for the brain was 102. We demonstrate the presence of three paired brain nerves. Brain nerve 1 traces into the epidermis of the upper lip region and consists of several fibers with some supportive bulb cells in its course. Brain nerve 2 innervates oral sensory organs and brain nerve 3 innervates the ciliary ring of the gill slits and lateral epidermis. Brain nerve 3 is asymmetric, with the right nerve consisting of two neurites originating posterior to the left one that contains three neurites. Similarities and differences to the anatomy of the brain of the model species Oikopleura dioica are discussed. We interpret the small number of cells in the brain of B. stygius as an evolutionary trace of miniaturization and conclude that giant appendicularians evolved from a small, progenetic ancestor that secondarily increased in size within Appendicularia.
    Content: Peer Reviewed
    In: Hoboken, NJ : Wiley-Blackwell, 284,7, 0362-2525
    In: 1097-4687
    Language: English
    URL: Volltext  (kostenfrei)
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  • 3
    UID:
    edochu_18452_27381
    Format: 1 Online-Ressource (11 Seiten)
    ISSN: 0720-213X , 0720-213X
    Content: The planktonic Oikopleura dioica belongs to Tunicata, the probable sister taxon to Craniota, and might show plesiomorphic characters, conserved from the common lineage of Tunicata and Craniota. In O. dioica a pericardium in a position similar to other chordates but also to the heart and pericardium of craniates is found. Surprisingly, little is known about the ultrastructure of the pericardium in O. dioica. Here, we show based on electron microscopy that the pericardium is completely lined by a single layer of 16 epithelial cells: 6 epithelial myocardial cells on the left side of the pericardium and 10 peritoneal cells constituting the right side. One of the peritoneal cells, situated at the ventral border between peritoneal cells and myocardial cells has an extension that anchors the pericardium to the basal lamina beneath the latero-ventral epidermis. The primary body cavity of O. dioica appears quite uniformly clear in electron microscopic aspect but several sheets, resembling the basal lamina of the pericardium cross the larger spaces of the body cavity and connect to the pericardial basal lamina. This is the first detailed description of two distinct cell types in the epithelial lining of the pericardium of O. dioica. In comparison with other chordates, we conclude that two cell types can be reconstructed for the last common ancestor of Chordata at least. The position of the pericardium at the intersection of trunk and tail in combination with the basal-lamina like sheets spanning the hemocoel is probably of importance for the function of the circulation of the hemocoelic fluid. Similar to the tail, the axis of the pericardium is shifted through 90 degrees to the left as compared to the main body axis of the trunk and we infer that this shift is an apomorphic character of Appendicularia.
    Content: Peer Reviewed
    In: New York : Springer, 140,4, Seiten 527-537, 0720-213X
    Language: English
    URL: Volltext  (kostenfrei)
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  • 4
    UID:
    edochu_18452_24004
    Format: 1 Online-Ressource (40 Seiten)
    ISSN: 2748-5234
    Content: Zeitschrift zur Kursreise der Freien Universität Berlin (Deutschland) an die Kristinebergs Marina Forskningsstation (Schweden)
    Content: Journal of the Graduate Course of the Freie Universiät Berlin (Germany) at Kristinebergs Marina Forskningsstation (Sweden)
    Content: Peer Reviewed
    Language: German
    URL: Volltext  (kostenfrei)
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  • 5
    Online Resource
    Online Resource
    Berlin : Humboldt-Universität zu Berlin
    UID:
    edochu_18452_23989
    Format: 1 Online-Ressource (7 Seiten)
    ISSN: 2748-5234 , 2748-5234
    Content: In the Wadden sea of Sylt Littorina littorea constitutes a wide spreaded species of snails. Since L. littorea possesses no defence mechanisms against settling by epibionts such as chemical barricades, the periwinkles are often strongly overgrown by barnacles and larval states of mussels and oysters. The most common epibiont on L. littorea is the barnacle Balanus crenatus. In this study we examine the effects of barnacle overgrowth on the agility of L. littorea. In order to analyse the influence of heavy overgrowth, individuals were sampled, weighed and categorized. Three experimental groups, two with contrasting severity of overgrowth and one with removed barnacles, were tested. Experiments revealed that heavy barnacle overgrowth affected the mobility of the periwinkles substantially. Moreover snails with removed barnacles performed as successful or occasionally more successful than snails without barnacles. This might demonstrate a certain training effect of snails with removed barnacles due to their adaptation to a heavier weight load.
    Content: Im Sylter Wattenmeer ist Littorina littorea eine weit verbreitete Schneckenart. Da L. littorea keine Abwehrmechanismen gegen Besiedelung durch Epibionten wie chemische Barrikaden besitzt, sind die Strandschnecken oft stark von Seepocken und Larvenstadien von Muscheln und Austern bewachsen. Der häufigste Epibiont auf L. littorea ist der Seepocken Balanus crenatus. In dieser Studie untersuchen wir die Auswirkungen von Seepockenüberwucherung auf die Beweglichkeit von L. littorea. Um den Einfluss starker Überwucherung zu analysieren, wurden Individuen beprobt, gewogen und kategorisiert. Drei Versuchsgruppen, zwei mit kontrastierendem Bewuchs und eine mit entfernten Seepocken, wurden getestet. Experimente zeigten, dass starkes Überwachsen von Seepocken die Beweglichkeit der Strandschnecken erheblich beeinträchtigte. Außerdem schnitten Schnecken mit entfernten Seepocken genauso erfolgreich oder gelegentlich erfolgreicher ab als Schnecken ohne Seepocken. Dies könnte einen gewissen Trainingseffekt von Schnecken mit entfernten Seepocken aufgrund ihrer Anpassung an eine höhere Gewichtsbelastung zeigen.
    Content: Peer Reviewed
    In: Proceedings in Marine Biology / Thomas Stach, , 2021, Volume 3,2019(2021),Number 2, Seiten 20-26, 2748-5234
    Language: German
    URL: Volltext  (kostenfrei)
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