Über die Rotatorienfauna in Bromelien-Phytotelmata in Jamaika (Aschelminthes: Rotatoria) : mit 2 Tabellen

Während eines Forschungsaufenthaltes in Jamaika, August bis Oktober 1991, wurden von einer Gruppe der AG Aquatische Ökologie der Universität Oldenburg/O. aus Phytotelmata der bodenständigen Bromelie Aechmea paniculigera GRISEB zwei Probenserien entnommen, um sie auf ihren Bestand an Rotatorien zu untersuchen. Es wurden 13 monogononte und 8 digononte (bdelloide) Morphen gefunden. Da neben lethalen auch Konservierungsartefakte die Identifizierung behinderten, konnten nur 17 Species bestimmt werden. Diese, darunter auch die bisher unbekannte Lecane (Monostyla) janetzkyi nov. spec., werden mit Bemerkungen zu ihrer systematischen Stellung, Taxonomie und Biogeographie sowie mit Abbildungen dargestellt.During a study visit to Jamaica (August-October 1991) a team of the AG Aquatic Ecology of Oldenburg University took two series of sampies from phytotelmata of the terrestrial bromeliad Aechmea paniculigera GRISEBin order to investigate the presence of rotifers. 13 Monogononta and 8 Digononta (Bdelloidae) were found. Since identification was not only hindered by lethal but also by preserving artifacts, only 17 species could be identified, including Lecane (Monostyla) janetzkyi nov. spec. These species will be presented along with specifications regarding their systematical position, taxonomy and biogeography as weil as by illustrations

Zur Kenntnis der limnischen Rotatorienfauna Jamaikas (Rotatoria: Aschelminthes) : Teil 1 ; mit 2 Tabellen

Im Rahmen eines Forschungsvorhabens über die Rotatorienfauna Jamaikas wurden 117 Proben (Juni bis August 1993) genommen. Es konnten 149 Morphen nachgewiesen werden, davon 127 monogononte und 22 digononte Formen. Da Konservierungsartefakte die Identifizierung behinderten, konnten nur 143 Spezies bestimmt werden, darunter auch Cephalodella irisae n.sp. und Cephalodella intuta jamaicaiensis n.ssp. Die wichtigsten Arten werden mit Bemerkungen zu ihrer systematischen Stellung, Taxonomie und Biogeographie dargestellt.During a study (June-August 1993) 117 samples were taken in order to investigate the presence of limnetic rotifers in Jamaica. 149 different forms were found: 127 Monogononta and 22 Digononta. Since identification was hindered by preserving artifacts, only 143 species could be determined, including Cephalodella irisae n.sp. and Cephalodella intuta jamaicaiensis n.ssp. The most interesting species will be presented along with remarks regarding their systematical position, taxonomy and biogeography

Zur Kenntnis der limnischen Rotatorienfauna Jamaikas (Rotifera) : Teil 2

Während der zweiten Feldphase (März bis April 1994) des Forschungsvorhabens über die Rotatorienfauna Jamaikas wurden 39 Proben genommen. Es konnten 135 Morphen nachgewiesen werden, davon 120 monogononte und 15 digononte Formen. Daneben wurden Formen aus 6 Gattungen beobachtet, deren Identifikation aufgrund von Konservierungsartefakten nicht möglich war. Von den 135 Morphen sind 61 zum ersten Mal für Jamaika nachgewiesen; insgesamt sind für diese Insel jetzt 211 Rotatorien bekannt. Die wichtigsten Arten werden mit Bemerkungen zu ihrer Taxonomie, Biogeographie und Ökologie dargestellt.During a second field study (March-April 1994) as part of a research project about limnetic rotifers in Jamaica 39 sampies were taken. 135 different forms were found: 120 Monogononta and 15 Digononta. Further types belonging to six genera could not be identified to species level, since determination was hindered by preserving artifacts. Out of 135 rotifers, 61 are listed for Jamaica for the first time; all in all, 211 rotifers are now known for this island. The most important species will be presented along with remarks regarding their taxonomy, biogeography and ecology

Palladiumreiche Telluride

Die palladiumreichen Telluride Pd13Te3, Pd{20-X}Te7, Pd8Te3 und Pd5Te2 wurden im Rahmen dieser Arbeit hergestellt und strukturell charakterisiert. Hindernisse bei der Kristallzucht, die durch das thermische und kinetische Verhalten der Verbindungen bedingt sind, wurden durch Kristallzucht mittels chemischen Transports umgangen. Zusätzlich wurde durch Synthese von Pd4Br4Te3 erstmals über eine Festphasensynthese Zugang zu einem weiteren Platinmetallhalogenidchalkogenid geschaffen. Die Synthese der Palladiumtelluride erfolgte bei Temperaturen im Bereich von 730~K bis 1200~K unter Zusatz von Palladiumchlorid oder Palladiumbromid in evakuierten Quarzglasampullen. Röntgen-Pulverdiffraktometrie wurde zur Phasenanalyse, in Kombination mit Thermoanalyse zur Ermittlung des thermischen Verhaltens einzelner Phasen und der Phasenbeziehungen herangezogen. Die strukturelle Charakterisierung erfolgte mittels Rönt-gen-Einkristallbeugungsmethoden. Die Strukturen wurden zu einfachen Strukturtypen in Beziehung gesetzt, wenn möglich mittels Gruppe-Untergruppe-Analyse. Temperaturabhängige Leitfähigkeitsmessungen und magnetische Messungen gestatteten die Ermittlung der Eigenschaften einzelner Verbindungen. XANES-Untersuchungen an Pd4Br4Te3 und Referenzsubstanzen gaben Aufschluß über die Valenzzustände der Komponenten in Pd4Br4Te3. Ergebnisse von extended-Hückel-Rechnungen lieferten Einblicke in Charakteristika der Elektronenstruktur der Verbindungen

The LIM-only protein FHL2 interacts with β-catenin and promotes differentiation of mouse myoblasts

FHL2 is a LIM-domain protein expressed in myoblasts but down-regulated in malignant rhabdomyosarcoma cells, suggesting an important role of FHL2 in muscle development. To investigate the importance of FHL2 during myoblast differentiation, we performed a yeast two-hybrid screen using a cDNA library derived from myoblasts induced for differentiation. We identified β-catenin as a novel interaction partner of FHL2 and confirmed the specificity of association by direct in vitro binding tests and coimmunoprecipitation assays from cell lysates. Deletion analysis of both proteins revealed that the NH2-terminal part of β-catenin is sufficient for binding in yeast, but addition of the first armadillo repeat is necessary for binding FHL2 in mammalian cells, whereas the presence of all four LIM domains of FHL2 is needed for the interaction. Expression of FHL2 counteracts β-catenin–mediated activation of a TCF/LEF-dependent reporter gene in a dose-dependent and muscle cell–specific manner. After injection into Xenopus embryos, FHL2 inhibited the β-catenin–induced axis duplication. C2C12 mouse myoblasts stably expressing FHL2 show increased myogenic differentiation reflected by accelerated myotube formation and expression of muscle-specific proteins. These data imply that FHL2 is a muscle-specific repressor of LEF/TCF target genes and promotes myogenic differentiation by interacting with β-catenin

FSscan: a mechanism-based program to identify +1 ribosomal frameshift hotspots

In +1 programmed ribosomal frameshifting (PRF), ribosomes skip one nucleotide toward the 3′-end during translation. Most of the genes known to demonstrate +1 PRF have been discovered by chance or by searching homologous genes. Here, a bioinformatic framework called FSscan is developed to perform a systematic search for potential +1 frameshift sites in the Escherichia coli genome. Based on a current state of the art understanding of the mechanism of +1 PRF, FSscan calculates scores for a 16-nt window along a gene sequence according to different effects of the stimulatory signals, and ribosome E-, P- and A-site interactions. FSscan successfully identified the +1 PRF site in prfB and predicted yehP, pepP, nuoE and cheA as +1 frameshift candidates in the E. coli genome. Empirical results demonstrated that potential +1 frameshift sequences identified promoted significant levels of +1 frameshifting in vivo. Mass spectrometry analysis confirmed the presence of the frameshifted proteins expressed from a yehP-egfp fusion construct. FSscan allows a genome-wide and systematic search for +1 frameshift sites in E. coli. The results have implications for bioinformatic identification of novel frameshift proteins, ribosomal frameshifting, coding sequence detection and the application of mass spectrometry on studying frameshift proteins

Spatial Distribution of Cryptic Species Diversity in European Freshwater Amphipods (Gammarus fossarum) as Revealed by Pyrosequencing

In order to understand and protect ecosystems, local gene pools need to be evaluated with respect to their uniqueness. Cryptic species present a challenge in this context because their presence, if unrecognized, may lead to serious misjudgement of the distribution of evolutionarily distinct genetic entities. In this study, we describe the current geographical distribution of cryptic species of the ecologically important stream amphipod Gammarus fossarum (types A, B and C). We use a novel pyrosequencing assay for molecular species identification and survey 62 populations in Switzerland, plus several populations in Germany and eastern France. In addition, we compile data from previous publications (mainly Germany). A clear transition is observed from type A in the east (Danube and Po drainages) to types B and, more rarely, C in the west (Meuse, Rhone, and four smaller French river systems). Within the Rhine drainage, the cryptic species meet in a contact zone which spans the entire G. fossarum distribution range from north to south. This large-scale geographical sorting indicates that types A and B persisted in separate refugia during Pleistocene glaciations. Within the contact zone, the species rarely co-occur at the same site, suggesting that ecological processes may preclude long-term coexistence. The clear phylogeographical signal observed in this study implies that, in many parts of Europe, only one of the cryptic species is present