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Chapter III 55 18 EVOLUTION & DEVELOPMENT Vol. 12, No. 1, January--February 2010 Fig. 1. Muscle development in Novocrania anomala. Overlay of maximum projection micrographs from phalloidin staining and light micrographs. Anterior faces upwards and scale bars equal 50 mm. (A) Larva with anterior lobe (AL), posterior lobe (PL), and early signs of F-actin in the three pairs of setae pouches (arrows) along the dorsal ridge of the posterior lobe. (B) Larva with setae (se), anterior lobe (AL), posterior lobe (PL), setae pouch muscles (arrows), homogenously distributed transversal muscles (asterisks), and a distinct F-actin-rich area (arrowheads), which might be involved in cementing the larva to the substrate during settlement. (C) Later larval stage with setae pouch muscles (arrows), medioventral longitudinal muscles (empty arrows), and F-actin-rich area (arrowhead) on the dorsal side. (D) Metamorphic competent larva in ventral view with setae (se) and setae pouch muscles (arrows), which are ventrally interconnected by two strands of medioventral longitudinal muscles (empty arrows). The medioventral longitudinal muscles are interconnected by transversal muscles, which at this stage are concentrated into three bundles (asterisks). (E) Specimen during metamorphosis with remnants of larval setae pouch muscles (arrows) and larval medioventral longitudinal muscles (empty arrows), which are most probably undergoing resorption. The adult anterior adductor muscles (aad) start to develop. (F) Juvenile with mantle margin muscles (mm), anterior adductor muscle (aad), oblique muscle (ob), and posterior adductor muscles (pad). (G–I) Three-dimensional reconstruction of the dataset shown in (D). (G) Ventral view of the musculature of a fully developed larva with medioventral longitudinal muscles (red), setae pouch muscles (yellow), and transversal muscle (asterisk). (H) Same specimen as in (G), anterior view. (I) Same specimen as in (G), dorsal view.
56 Chapter III Altenburger and Wanninger Brachiopod neuromuscular development 19 Fig. 2. Semischematic representation of the larval musculature of craniiform and rhynchonelliform brachiopods. (A) Musculature of Novocrania anomala with setae pouch muscles (red circles), medioventral longitudinal muscles (white), and transversal muscles (yellow-grey). Size of the specimen is approximately 150 mm. (B) Musculature of Argyrotheca cordata based on Altenburger and Wanninger (2009) with pedicle muscles (beige), longitudinal muscles (orange), central mantle muscles (brown), U-shaped muscle (green), setae pouch muscles (red circles), circular mantle muscle (light blue), serial mantle muscles (dark orange), setae muscles (purple), apical longitudinal muscles (dark blue), and apical transversal muscle (yellow). Size of the specimen is approximately 280 mm. juvenile musculature comprises mantle margin muscles, oblique muscles, as well as anterior and posterior adductor muscles (Fig. 1F). Neurogenesis The first signals of serotonin-like immunoreactivity appear in fully developed, metamorphic competent, bilobed larvae at approximately 86 hpf (Table 1). At this stage, four flaskshaped cells are present in the anterior-most part of the apical lobe (Fig. 3, A–D). They are oriented in different directions with only one pointing toward the apical pole of the larva. The flask-shaped cells are connected to two ventral neurites that extend posteriorly (Fig. 3, A–D). The flask-shaped cells are lost during metamorphosis, and early juveniles have two ventral neurites that project from the anterior lobe into the posterior lobe (Fig. 3E). During subsequent development, the ventral neurites become interconnected by a median commissure in the mid-part of the juvenile (Fig. 3F). The axonal marker a-tubulin is first expressed in juveniles 5 days after metamorphosis (Fig. 4A). Two solid neurite bundles develop ventrolaterally in the anterior lobe of the juvenile and subsequently grow in posterior direction into the posterior lobe (Fig. 4B). Later in development, these neurite bundles close by an anterior and a posterior commissure, and the median commissure is established (Fig. 4, C–F). Serially arranged mantle neurites extend from the anterior part of the ventral neurite bundles in a lateral direction toward the mantle margin of the juvenile (Fig. 4, B–F). Comparison of the position of the a-tubulin signal in the juvenile and the serotonin-like signal in the larva suggests that the larval ventral neurites are the earliest neurites of the future ventral neurite bundles of the juvenile. Table 1. Landmarks of Novocrania anomala development at 141C Age (hours post fertilization) Gross morphology Myoanatomy as inferred by F-actin staining 3–4 First cleavage No signal No signal 26–30 Swimming, spherical gastrula No signal No signal 42–49 Swimming, elongated gastrula No signal No signal 65–73 Swimming, bilobed larva with setae starting to develop First signals of actin in setae pouches (Fig. 1A) No signal 86–96 Fully established, swimming, bilobed larva with long setae 168 Settled juvenile after metamorphosis Fully developed larval musculature with setae pouch muscles, longitudinal muscles, and transversal muscles (Fig. 1D) Juvenile with mantle margin muscles, anterior adductors, and posterior adductors (Fig. 1F) Neuroanatomy as inferred by antibody staining Larval nervous system with four flask-shaped cells in the apical organ and two ventral neurites (Fig. 3, B–D) Juvenile with two ventral neurite bundles, commissures, and serially arranged neurites (Figs. 3, E and F and 4, A–F)
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Comparative neurogenesis, muscle de
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2 Principal supervisor Assoc. P
Page 5 and 6: 4 Preface This thesis presents
Page 7 and 8: 6 Abstract Brachiopods are a sm
Page 9 and 10: 8 Acknowledgements The endeavou
Page 11 and 12: 10 Introduction Nervous system Micr
Page 13 and 14: 12 Material and methods Material an
Page 15 and 16: 14 Material and methods purpuratus,
Page 17 and 18: 16 Results and discussion Results a
Page 19 and 20: 18 Results and discussion posterior
Page 21 and 22: 20 Results and discussion Myogenesi
Page 23 and 24: 22 Results and discussion Wanninger
Page 25 and 26: 24 Results and discussion Growth pa
Page 27 and 28: 26 Results and discussion argument
Page 29 and 30: 28 References References Abdelkhale
Page 31 and 32: 30 References priapulids and protos
Page 33 and 34: 32 References James, M. A., Ansell,
Page 35 and 36: 34 References regionalization, prol
Page 37 and 38: 36 References 211. Williams, A., Ca
Page 39 and 40: 38 Chapter II Frontiers in Zoology
Page 53 and 54: 52 Chapter III Chapter III Altenbur
Page 55: 54 Chapter III Altenburger and Wann
Page 59 and 60: 58 Chapter III Altenburger and Wann
Page 61 and 62: 60 Chapter III Altenburger and Wann
Page 63 and 64: 62 Chapter IV Chapter IV Altenburge
Page 65 and 66: 64 Submitted manuscript Chapter IV
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