Literaturberichte

Ohne Zusammenfassung     

Elektronenmikroskopische Untersuchung eines Mechanorezeptors von Evertebraten (Priapuliden,Oligochaeten)

Zusammenfassung Rezeptoren von Priapulus caudatus und Rhynchelmis limosella werden elektronenmikroskopisch untersucht. Ihre Strukturen stimmen in folgenden Merkmalen überein: Apikal steht eine Zilie, die von regelmäßig angeordneten Mikrovilli umgeben wird. Das Cytoplasma der Mikrovilli ist zentral verdichtet und im übrigen Bereich von Filamenten ausgefüllt, die im Perikaryon wurzeln. Im distalen Teil der Zelle liegt ein reich entwickeltes glattes E. R., darunter folgen Tubuli. Die Zellen werden reich innerviert.Aufgrund der strukturellen Übereinstimmung mit Mechanorezeptoren anderer Tiergruppen wird den Rezeptoren der untersuchten Formen ebenfalls eine mechanorezeptive Funktion zugeschrieben.

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Electron microscopic observations on a mechanoreceptor of invertebrates (Priapulida, Oligochaeta)

Summary Epidermal receptor cells of Priapulus caudatus and Rhynchelmis limosella have been investigated with the electron microscope. The following structural peculiarities characterize these cells: an apical cilium is surrounded by regularly arranged microvilli, which contain filaments extending into the cytoplasm of the cell body. The central part of the microvilli is electron dense. The apical part of the cell contains abundant tubules of smooth E. R., below which microtubules are located. The cells are richly innervated.These elements are interpreted to represent mechanoreceptors because they have the above mentioned structures in common with mechanoreceptors of other invertebrate groups.

Für die Überlassung eines Arbeitsplatzes im Anatomischen Institut und im Institut für Pharmakognosie Kiel danken wir Herrn Prof. Dr. W. Bargmann und Herrn Prof. Dr. O. Moritz.     

web cellHTS2: A web-application for the analysis of high-throughput screening data

Background  

The analysis of high-throughput screening data sets is an expanding field in bioinformatics. High-throughput screens by RNAi generate large primary data sets which need to be analyzed and annotated to identify relevant phenotypic hits. Large-scale RNAi screens are frequently used to identify novel factors that influence a broad range of cellular processes, including signaling pathway activity, cell proliferation, and host cell infection. Here, we present a web-based application utility for the end-to-end analysis of large cell-based screening experiments by cellHTS2.     

Lack of effect of photoperiod on metabolism of exogenous GA19 and GA1 in Salix pentandra seedlings

The effect of photoperiod on metabolism of 16,17-[³H₂]GA₁₉, and 1.2-[³H₂]GA₁ applied to intact seedlings of Salix pentandra, was investigated. No difference was found in conversion of 16,17-[³H₂]GA₁₉ to 16,17-[³H₂]GA₂₀, and 16,17-[³H₂]GA₁, or in metabolism of 1,2-[³H₂]GA₁ to [³H]GA₈ between plants grown in continuous light and plants exposed for 14 days to a 12-h photoperiod. Also, leaf discs from plants grown in long or short days, converted 16,17-[³H₂]GA₁₉ both in light and darkness. These data on metabolism of 16,17-[³H₂]GA₁₉, contrast with previous results, which have indicated a photoperiodic control of the metabolism of GA₁₉ to GA₂₀ in S. pentandra. Presence of these applied labelled GAs and their metabolites in different parts of seedlings was recorded, after application to intact seedlings as well as to isolated plant parts. When 16,17-[³H₂]GA₁₉ was applied through the roots of intact plants, the relative amounts of 16,17-[³H₂]GA₁ present in leaves and shoot apices were higher than in roots and stems. In corresponding experiments with 1,2-[³H₂]GA₁, relatively higher amounts of [³H₂]GA₈ were found in roots and stems than in leaves and shoot apices. Twenty-four hours after application of 16,17-[³H₂]GA₁₉ to isolated plant parts, 16,17-[³H₂]GA₂₀ and 16,17-[³H₂]GA₁ were found in leaves and roots, but not in internodes. Incubation of isolated plant parts with 1,2-[³H₂]GA₁ for 24 h resulted in presence of [³H]GA₈ in all parts. The results mentioned above were obtained by monitoring metabolites by HPLC with on-line radio counting. The conversions of 17-[²H₂]GA₁₉ to 17-[²H₂]GA₂₀ and 17-[²H₂]GA₁ in shoot apices and whole seedlings, and of 17-[²H₂]GA₈ in whole seedlings, were confirmed by GC-MS.     

The social parasite Phengaris (Maculinea) nausithous affects genetic diversity within Myrmica rubra host ant colonies

Evolutionary theory predicts that high genetic variation maintains plasticity in a species’ response to parasite pressure. However, higher genetic diversity might also cause easier infiltration by social parasites, because odour diversity is high and nest-mate recognition poor. Here we test if the obligate myrmecophile Lycaenid butterfly Phengaris nausithous, a parasite of colonies of the highly polygynous ant Myrmica rubra causes local adaptation by enhancing genetic variance in parasitized versus non parasitized ant populations M. rubra colonies from six infested and three uninfested sites were assayed at five microsatellite loci to quantify genetic variation. Our results reveal isolation by distance and a significantly enhanced intracolonial variance due to the parasite pressure.     

Fiber‐type composition in the perivertebral musculature of lizards: Implications for the evolution of the diapsid trunk muscles

The perivertebral musculature of lizards is critical for the stabilization and the mobilization of the trunk during locomotion. Some trunk muscles are also involved in ventilation. This dual function of trunk muscles in locomotion and ventilation leads to a biomechanical conflict in many lizards and constrains their ability to breathe while running (“axial constraint”) which likely is reflected by their high anaerobic scope. Furthermore, different foraging and predator‐escape strategies were shown to correlate with the metabolic profile of locomotor muscles in lizards. Because knowledge of muscle's fiber‐type composition may help to reveal a muscle's functional properties, we investigated the distribution pattern of muscle fiber types in the perivertebral musculature in two small lizard species with a generalized body shape and subjected to the axial constraint (Dipsosaurus dorsalis, Acanthodactylus maculatus) and one species that circumvents the axial constraint by means of gular pumping (Varanus exanthematicus). Additionally, these species differ in their predator‐escape and foraging behaviors. Using refined enzyme‐histochemical protocols, muscle fiber types were differentiated in serial cross‐sections through the trunk, maintaining the anatomical relationships between the skeleton and the musculature. The fiber composition in Dipsosaurus and Acanthodactylus showed a highly glycolytic profile, consistent with their intermittent locomotor style and reliance on anaerobic metabolism during activity. Because early representatives of diapsids resemble these two species in several postcranial characters, we suggest that this glycolytic profile represents the plesiomorphic condition for diapsids. In Varanus, we found a high proportion of oxidative fibers in all muscles, which is in accordance with its high aerobic scope and capability of sustained locomotion. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.