Intermuscular bones in acanthomorphs

25 p. : ill. ; 26 cm.Includes bibliographical references (p. 24-25).Myosepta of selected representatives of the following acanthomorph taxa were investigated: Polymixiiformes, Lampridiformes, Paracanthopterygii, Beryciformes, Atherinomorpha, and Percomorpha. A new technique, microdissection of alcohol-stored specimens and polarized-light microscopy, was applied to study the three-dimensional architecture of connective tissue fibers in epaxial parts of myosepta. Several invariable similarities were present in all taxa: an epineural series of tendons or bones and a tendinous series of lateral bands in the epaxial part of the myoseptum, and an epicentral series of tendons or bones in the horizontal septum. Patterson and Johnson's (1995) hypothesis that the single bony series of intermusculars in higher acanthomorphs is the homolog of epineurals of lower teleosts is tested. Our results contradict their hypothesis at essential points because we discovered epineural tendons in the normal epaxial position in different acanthomorphs that were considered to lack these. We conclude that the first intermuscular bone of Polymixia is an epicentral, the single series of intermuscular bones of Holacanthopterygii are epicentrals, and the neoneurals of some percomorphs are normal epineurals. Phylogenetic implications of our results are discussed

Leitfaden zur Forstlichen Bodenschutzkalkung in Sachsen (Kalkungsleitfaden)

Waldböden nehmen mit ihrer Filter-, Puffer- und Speicherfunktion im Naturhaushalt eine zentrale Stellung ein. Nur ein gesunder Waldboden garantiert vitale, stabile Waldökosysteme und sauberes Wasser. Die Bodenschutzkalkung ist neben der Verminderung waldschädigender Emissionen ein wirkungsvolles Instrument, um insbesondere die eingetretenen Schädigungen des Boden zu beheben und auch für die nachfolgenden Generationen die Multifunktionalität der Waldökosysteme zu sichern. Der Leitfaden beschreibt ökologische Grundlagen, stellt die Entwicklung der Schadsituation in Sachsen dar und gibt im Technischen Teil Hilfestellungen zur fachlich fundierten forstlichen Planung, zu klaren vertraglichen Regelungen für die sorgfältige Ausführung durch sachkundige Service-Unternehmen sowie zur Durchführung von Kontrollen durch den Auftraggeber. Redaktionsschluss: 31.05.202

Hydrologische Eigenschaften typischer Waldhumusformen unter Gemeiner Kiefer im Nordostsächsischen Tiefland: Wasserspeicherung - Hydrophobie - Versickerung

Labor- und Felduntersuchungen zum Infiltrationsverhalten des Auflagehumus eines bestockungstypischen Reinbestandes aus Gemeiner Kiefer erlauben eine nähere Kennzeichnung seiner hydrologischen Funktionen. Während in der Vegetationsperiode 2014 eine mehrmalige Wiederbefeuchtung des Auflagehumus und Zwischenspeicherung auftritt, bleibt dieser im niederschlagsreicheren Folgejahr fast über die gesamte Vegetationsperiode trocken. Hier verzögert eine im Frühsommer induzierte Hydrophobie die Wiederbefeuchtung. Selbst nach Starkniederschlägen findet bis in den Winter keine nennenswerte Wasserspeicherung mehr statt. Gleichwohl wird die Humusauflage wegen ihres sehr hohen Gesamtporenvolumens ungehindert durchsickert, was zur wiederholten Aufsättigung des oberen Mineralbodens in der Vegetationszeit führt

Situated learning in the mobile age: mobile devices on a field trip to the sea

This study focuses on learning about fish biodiversity via mobile devices in a situated learning scenario. Mobile devices do not only facilitate relating the presented information to the real world in a direct way; they also allow the provision of dynamic representations on demand. This study asks whether mobile devices are suited to support knowledge acquisition in a situated learning scenario and whether providing dynamic content is an additional benefit of mobile devices in combination with a real-world experience. The study was conducted during a regular university course at the Mediterranean Sea. Students had to acquire knowledge on 18 Mediterranean fish species by using either static (n = 16) or dynamic learning materials (n = 17). An initial classroom activity was followed by a real-world experience with mobile devices (snorkelling activity). Learning outcomes were measured before and after snorkelling. A 2×2 mixed ANOVA revealed that students performed better after than before the mobile learning experience, whereas no main effect for learning material could be found. However, an interaction between both factors indicated that the knowledge gain in the dynamic group exceeded the knowledge gain in the static group. These results indicate that mobile devices are helpful to unfold the potential of dynamic visualisations for learning biodiversity in a situated learning scenario

Resegmentation is an ancestral feature of the gnathostome vertebral skeleton.

The vertebral skeleton is a defining feature of vertebrate animals. However, the mode of vertebral segmentation varies considerably between major lineages. In tetrapods, adjacent somite halves recombine to form a single vertebra through the process of 'resegmentation'. In teleost fishes, there is considerable mixing between cells of the anterior and posterior somite halves, without clear resegmentation. To determine whether resegmentation is a tetrapod novelty, or an ancestral feature of jawed vertebrates, we tested the relationship between somites and vertebrae in a cartilaginous fish, the skate (Leucoraja erinacea). Using cell lineage tracing, we show that skate trunk vertebrae arise through tetrapod-like resegmentation, with anterior and posterior halves of each vertebra deriving from adjacent somites. We further show that tail vertebrae also arise through resegmentation, though with a duplication of the number of vertebrae per body segment. These findings resolve axial resegmentation as an ancestral feature of the jawed vertebrate body plan

MetaMesh: A hierarchical computational model for design and fabrication of biomimetic armored surfaces

Many exoskeletons exhibit multifunctional performance by combining protection from rigid ceramic components with flexibility through articulated interfaces. Structure-to-function relationships of these natural bioarmors have been studied extensively, and initial development of structural (load-bearing) bioinspired armor materials, most often nacre-mimetic laminated composites, has been conducted. However, the translation of segmented and articulated armor to bioinspired surfaces and applications requires new computational constructs. We propose a novel hierarchical computational model, MetaMesh, that adapts a segmented fish scale armor system to fit complex “host surfaces”. We define a “host” surface as the overall geometrical form on top of which the scale units are computed. MetaMesh operates in three levels of resolution: (i) locally—to construct unit geometries based on shape parameters of scales as identified and characterized in the Polypterus senegalus exoskeleton, (ii) regionally—to encode articulated connection guides that adapt units with their neighbors according to directional schema in the mesh, and (iii) globally—to generatively extend the unit assembly over arbitrarily curved surfaces through global mesh optimization using a functional coefficient gradient. Simulation results provide the basis for further physiological and kinetic development. This study provides a methodology for the generation of biomimetic protective surfaces using segmented, articulated components that maintain mobility alongside full body coverage.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract No. W911NF-13-D-0001)United States. Army Research Office (Institute for Collaborative Biotechnologies (ICB), contract no. W911NF-09-D-0001)United States. Department of Defense (National Security Science and Engineering Faculty Fellowship Program (Grant No. N00244-09-1-0064)

The locomotor system of the ocean sunfish Mola mola (L.): role of gelatinous exoskeleton, horizontal septum, muscles and tendons

Adult ocean sunfish are the heaviest living teleosts. They have no axial musculature or caudal fin. Propulsion is by unpaired dorsal and anal fins; a pseudocaudal fin (‘clavus’) acts as a rudder. Despite common perception, young sunfish are active predators that swim quickly, beating their vertical fins in unison to generate lift‐based propulsion and attain cruising speeds similar to salmon and marlin. Here we show that the thick subcutaneous layer (or ‘capsule’), already known to provide positive buoyancy, is also crucial to locomotion. It provides two compartments, one for dorsal fin musculature and one for anal fin muscles, separated by a thick, fibrous, elastic horizontal septum that is bound to the capsule itself, the roof of the skull and the dorsal surface of the short vertebral column. The compartments are braced sagittally by bony haemal and neural spines. Both fins are powered by white muscles distributed laterally and red muscles located medially. The anal fin muscles are mostly aligned dorso‐ventrally and have origins on the septum and haemal spines. Dorsal fin muscles vary in orientation; many have origins on the capsule above the skull and run near‐horizontally and some bipennate muscles have origins on both capsule and septum. Such bipennate muscle arrangements have not been described previously in fishes. Fin muscles have hinged tendons that pass through capsular channels and radial cartilages to insertions on fin rays. The capsule is gelatinous (89.8% water) with a collagen and elastin meshwork. Greasy in texture, calculations indicate capsular buoyancy is partly provided by lipid. Capsule, septum and tendons provide elastic structures likely to enhance muscle action and support fast cruising