Reconstructing the Auditory Apparatus of Therapsids by Means of Neutron Tomography

AbstractThe internal cranial structure of mammalian ancestors, i.e. the therapsids or “mammal-like reptiles”, is crucial for understanding the early mammalian evolution. In the past therapsid skulls were investigated by mechanical sectioning or serial grinding, which was a very time-consuming and destructive process and could only be applied to non-valuable or poorly preserved specimens. As most therapsid skulls are embedded in terrestrial iron-rich sediments of Late Permian or Triassic age, i.e. so called “Red beds”, a successful investigation with X-Rays is often not possible.We successfully investigated therapsid skulls by means of neutron tomography at the facility ANTARES at FRM II in Munich using cold neutron radiation. This kind of radiation is able to penetrate iron-rich substances in the range between 5 and 15cm and produces a good contrast between matrix and bones, which enables segmentation of internal cranial structures such as bones, cavities and canals of nerves and blood vessels. In particular, neutron tomography combined with methods of 3D modeling was used here for the investigation and reconstruction of the auditory apparatus of therapsids

Regulation der respiratorischen Stoffwechselwege zur Energiegewinnung in D. shibae unter anaeroben Bedingungen mit Nitrat

Dinoroseobacter shibae is a marine bacterium and belongs to the ubiquitously found Roseobacter clade. Investigation of the genome sequence identified genes encoding enzymes of the anaerobic metabolism. 7 Crp/Fnr like regulators were annotated, which leads to the question for the gene regulatory network, proteomic and metabolomic networks controlling the transition between aerobic and anaerobic growth. To answer this question, an aerobic continuously cultivation of D. shibae in a chemostate in minimal media supplemented with was established. Time resolved shift experiments from oxic to anoxic growth conditions were performed to characterize the transcriptomic, proteomic and metabolomic adaptation of D. shibae. The transcriptome and proteome data revealed a strong expression of operons encoding proteins for the formation of the denitrification machinery. Furthermore, the expression of the genes encoding the Crp/Fnr like regulators dnrD, dnrE and dnrF was also found increased, which leads to the assumption of involvement in the regulatory network for the establishment of nitrate respiratory conditions. Moreover, the synthesis of PHB was observed under these conditions and verified by transmission electronic microscopy and HPLC analyses. Using a bioinformatics approach the phylogenetic affiliation of DnrE, DnrD and DnrF into the various subfamily of Crp/Fnr like regulators was achieved. Furthermore, comparative transcriptome analyses of wildtype and dnrF deletion mutant revealed the mainly repressing influence of DnrF on several genes encoding for enzymes of the energy generation machinery, transcription factors and iron-sulfur cluster proteins under oxic and anoxic conditions. This leads to the consumption of DnrF acts mainly as a oxygen independent repressor. To identify the essential genes of D. shibae for growth under nitrate respiratory conditions a transposon mutagenesis approach was established. Over 4500 mutants were screened for a growth failure under these conditions. Finally, 53 strains showed a growth defect or even no growth. Genes encoding the periplasmic nitrate reductase NapA and the molybdopterin biosynthesis protein MoeB were found to be essential. In comparison with the transcriptomic and proteomic profile of D. shibae only 3 genes (napA, phaA and the Na+/Pi antiporter gene Dshi_0543) showed an overlap of induced and essential. Furthermore, highly induced genes (nirS) are not essential for the growth under nitrate respiratory conditions.Dinoroseobacter shibae ist ein Meeresbakterium, das zu den ubiquitär zu findenden Roseobacter Cluster gehört. Die Untersuchung des sequenziertem Genoms identifizierte Gene, die für Enzyme des anaeroben Metabolismus codieren. 7 Crp/Fnr ähnliche Transkriptionsregulatoren annotiert, was die Frage nach dem genregulatorischem, proteomischem und metabolomischem Netzwerk aufwirft, das die Anpassung von aeroben zu anaeroben Wachstumsbedingungen kontrolliert. Daher wurde in dieser Arbeit zunächst eine kontinuierliche Kultivierung von Dinoroseobacter shibae im Chemostaten unter aeroben Bedingungen in Minimalmedium etabliert. Zeitaufgelöste Shift Experimente von oxischen zu nitratrespiratorischen Wachstumsbedingungen wurden zur Charakterisierung der Anpassung von D. shibae auf transkriptioneller, translationeller und metabolischer Ebene durchgeführt. Die Transkriptom- und Proteomdaten zeigten eine starke Expression der Operons, die für Proteine der Denitrifikation codieren. Weiterhin wurde die Expression von Genen, die für die Proteine der Crp/Fnr Familie dnrD, dnrE und dnrF codieren, auch induziert vorgefunden, was zu der Annahme führt, dass diese in das regulatorische Netzwerk der Adaption an Nitratrespiratorische Bedingungen beteiligt sind. Durch eine bioinformatische Stammbaumanalyse konnten DnrD, DnrE und DnrF in die Unterfamilie Dnr klassifiziert werden. Vergleichende DNA Microarray Experimente des Wildtyps und einer dnrF Deletionsmutante zeigten einen zumeist reprimierenden Einfluss von DnrF auf die Expression verschiedener Gene, codierend für Energiegewinnung, Transkriptionsfaktoren und Eisen-Schwefel Cluster Proteinen unter aeroben und anaeroben Bedingungen. Diese Ergebnisse weisen darauf hin, dass DnrF meist als Sauerstoff unabhängiger Repressor fungiert. Zur Identifizierung von essentiellen Genen, die in D. shibae für das Wachstum unter Nitratrespiratorischen Bedingungen benötigt werden, wurde eine Transposonmutagenese etabliert. Über 4500 Mutanten wurden nach Wachstumsversuche untersucht. Hier zeigten 53 Mutanten ein geringeres oder kein Wachstum. Essentiell für das Wachstum wurden z. B. die Gene, die für die periplasmatische Nitratreduktase NapA und das Molybdopterin Biosynthese Protein MoeB identifiziert. Im Vergleich mit dem Transkriptom und Proteom von D. shibae wurden nur 3 Gene (napA, phaA and the Na+/Pi antiporter gene Dshi_0543) identifiziert, die sowohl essentiell als auch induziert unter diesen Bedingungen sind

Morphological evolution of the mammalian jaw adductor complex

The evolution of the mammalian jaw during the transition from non-mammalian synapsids to crown mammals is a key event in vertebrate history and characterised by the gradual reduction of its individual bones into a single element and the concomitant transformation of the jaw joint and its incorporation into the middle ear complex. This osteological transformation is accompanied by a rearrangement and modification of the jaw adductor musculature, which is thought to have allowed the evolution of a more-efficient masticatory system in comparison to the plesiomorphic synapsid condition. While osteological characters relating to this transition are well documented in the fossil record, the exact arrangement and modifications of the individual adductor muscles during the cynodont–mammaliaform transition have been debated for nearly a century. We review the existing knowledge about the musculoskeletal evolution of the mammalian jaw adductor complex and evaluate previous hypotheses in the light of recently documented fossils that represent new specimens of existing species, which are of central importance to the mammalian origins debate. By employing computed tomography (CT) and digital reconstruction techniques to create three-dimensional models of the jaw adductor musculature in a number of representative non-mammalian cynodonts and mammaliaforms, we provide an updated perspective on mammalian jaw muscle evolution. As an emerging consensus, current evidence suggests that the mammal-like division of the jaw adductor musculature (into deep and superficial components of the m. masseter, the m. temporalis and the m. pterygoideus) was completed in Eucynodontia. The arrangement of the jaw adductor musculature in a mammalian fashion, with the m. pterygoideus group inserting on the dentary was completed in basal Mammaliaformes as suggested by the muscle reconstruction of Morganucodon oehleri. Consequently, transformation of the jaw adductor musculature from the ancestral (‘reptilian’) to the mammalian condition must have preceded the emergence of Mammalia and the full formation of the mammalian jaw joint. This suggests that the modification of the jaw adductor system played a pivotal role in the functional morphology and biomechanical stability of the jaw joint

Augmented laminography, a correlative 3D imaging method for revealing the inner structure of compressed fossils

Non-destructive imaging techniques can be extremely useful tools for the investigation and the assessment of palaeontological objects, as mechanical preparation of rare and valuable fossils is precluded in most cases. However, palaeontologists are often faced with the problem of choosing a method among a wide range of available techniques. In this case study, we employ x-ray computed tomography (CT) and computed laminography (CL) to study the first fossil xiphosuran from the Muschelkalk (Middle Triassic) of the Netherlands. The fossil is embedded in micritic limestone, with the taxonomically important dorsal shield invisible, and only the outline of its ventral part traceable. We demonstrate the complementarity of CT and CL which offers an excellent option to visualize characteristic diagnostic features. We introduce augmented laminography to correlate complementary information of the two methods in Fourier space, allowing to combine their advantages and finally providing increased anatomical information about the fossil. This method of augmented laminography enabled us to identify the xiphosuran as a representative of the genus Limulitella

The RNA-binding protein TTP is a global post-transcriptional regulator of feedback control in inflammation.

RNA-binding proteins (RBPs) facilitate post-transcriptional control of eukaryotic gene expression at multiple levels. The RBP tristetraprolin (TTP/Zfp36) is a signal-induced phosphorylated anti-inflammatory protein guiding unstable mRNAs of pro-inflammatory proteins for degradation and preventing translation. Using iCLIP, we have identified numerous mRNA targets bound by wild-type TTP and by a non-MK2-phosphorylatable TTP mutant (TTP-AA) in 1 h LPS-stimulated macrophages and correlated their interaction with TTP to changes at the level of mRNA abundance and translation in a transcriptome-wide manner. The close similarity of the transcriptomes of TTP-deficient and TTP-expressing macrophages upon short LPS stimulation suggested an effective inactivation of TTP by MK2, whereas retained RNA-binding capacity of TTP-AA to 3'UTRs caused profound changes in the transcriptome and translatome, altered NF-κB-activation and induced cell death. Increased TTP binding to the 3'UTR of feedback inhibitor mRNAs, such as Ier3, Dusp1 or Tnfaip3, in the absence of MK2-dependent TTP neutralization resulted in a strong reduction of their protein synthesis contributing to the deregulation of the NF-κB-signaling pathway. Taken together, our study uncovers a role of TTP as a suppressor of feedback inhibitors of inflammation and highlights the importance of fine-tuned TTP activity-regulation by MK2 in order to control the pro-inflammatory response

Inner ear morphology of diadectomorphs and seymouriamorphs (Tetrapoda) uncovered by high‐resolution x‐ray microcomputed tomography, and the origin of the amniote crown group

The origin of amniotes was a key event in vertebrate evolution, enabling tetrapods to break their ties with water and invade terrestrial environments. Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Using high-resolution X-ray microcomputed tomography, we reveal the three-dimensional architecture of the well preserved endosseous labyrinth of the inner ear in representative species belonging to both groups. Data from the inner ear are coded in a new cladistic matrix of stem and primitive crown amniotes. Both maximum parsimony and Bayesian inference analyses retrieve seymouriamorphs as derived non-crown amniotes and diadectomorphs as sister group to synapsids. If confirmed, this sister group relationship invites re-examination of character polarity near the roots of the crown amniote radiation. Major changes in the endosseous labyrinth and adjacent braincase regions are mapped across the transition from non-amniote to amniote tetrapods, and include: a ventral shift of the cochlear recess relative to the vestibule and the semicircular canals; cochlear recess (primitively housed exclusively within the opisthotic) accommodated within both the prootic and the opisthotic; development of a distinct fossa subarcuata. The inner ear of seymouriamorphs foreshadows conditions of more derived groups, whereas that of diadectomorphs shows a mosaic of plesiomorphic and apomorphic traits, some of which are unambiguously amniote-like, including a distinct and pyramid-like cochlear recess

Staatliche Exportkreditgarantien im Spannungsfeld zwischen internationalen Wertschöpfungsketten und nationalem Förderauftrag. Ansätze zur Weiterentwicklung des bestehenden Modells für die deutsche Export Credit Agency

Using the example of German export credit guarantees, this study examines the current and future challenges for state export credit agencies resulting from the increasing internationalisation of national exporters. The focus is on further developing the federal promotion scheme in the area of tension between the national promotion mandate and the requirements of global value chains. The perspective of this paper is on foreign content and local costs. Another focus is on financing by national and international banks, which is essential for export transactions. Financing bottlenecks are concretised and examined. A critical literature review reveals the lack of academic research on this field, which is essential for ECAs, banks, and academia, and thus the research gap that needs to be closed. With reference to this research gap, the thesis highlights the need for change and implementation proposals using the example of a diverse range of actors in the EU and the OECD. The research was conducted using two methods of empirical social research. By using both qualitative methods in the form of expert interviews and quantitative methods utilizing a survey, a mixed-methods approach was realised. The survey of participants from different sectors and countries enabled a multilevel view and thus a multidimensional view of the research object. EU and OECD ECAs, industry experts as well as banks and exporters were interviewed as part of the research. This approach made it possible to question and analyse the solutions of other countries and institutions. Against the background of existing research and operational challenges, they could be put in relation to the existing model of export credit guarantees in Germany. The study results include the definition of a new catalogue of criteria for determining eligibility, proposals and concepts regarding a paradigm shift from a national-content to a national-interest approach. The necessity of a change in individual components of the existing OECD consensus is decisively presented. To this end, possibilities of how to close financing bottlenecks are identified and already tested models of other countries are presented and examined with regard to their implementability. As a result, this work opens up a new and comprehensive view of the challenges that arise for the aforementioned institutions in a multinational environment and will continue to gain in importance in the future

First evidence of arthropod herbivory in calamitalean stems from the Pennsylvanian of Germany

Arthropod borings are commonly described from pteridophyte and gymnosperm wood in the late Palaeozoic, but they are almost unknown from calamitalean stems. In this paper, a new type of boring in calamital- ean stems from two German localities is reported. These are the mine dumps of Plötz near Halle (Saale), Saale Basin, (Wettin Subformation, Latest Pennsylvanian, Gzhelian, Stephanian C) and the Piesberg quarry near Osnabrück, Subvariscan Foreland Basin, (Osnabrück Formation, Middle Pennsylvanian, latest Moscovian, Asturian/ Westphalian D). Most borings were found in marginal parenchyma of the internodes. They run longitudinally through the pith. The borings are preserved as three-dimensional casts that protrude on the surface of considerably compressed pith casts. This unique preservation of the boring casts required special taphonomic conditions, such as rapid burial coupled with different sediment infilling of the borings and the pith cavity, as well as anoxic conditions to prevent decomposition of the non-resistant parenchyma. Most borings are between 3 to 5 mm wide and contain two classes of invertebrate coprolites: the smaller coprolites are sub-spheroidal in shape and measure (37 to 74) x (37 to 63) pm in diameter. The larger coprolites are also sub-spheroidal and range between (88 to'158) x (68 to 123) pm in diameter. The coprolites, the morphology of the borings, as well as the feeding strategy of the arthropods, suggest that the tunnel system was most likely produced by small millipedes (Myriapoda) and probably also visited by oribatid mites

Dysphagie infolge einer isolierten oesophago-trachealen Fistel bei einem Neugeborenen

Hintergrund: Ursache einer Dysphagie im Säuglingsalter können angeborene Fisteln bei einer Fehlbildung von Speise- und Luftröhre sein (Häufigkeit 1 von 2.000 bis 4.000 Lebendgeburten). Isolierte Fisteln treten bei 1 zu 80.000 Geburten auf.Fallbericht: Anamnese: Nach Geburt zeigte das reife Neugeborene (41 SSW) beim Füttern auffällige Sättigungsabfälle, kurze Bradykardien, Hustenanfälle. Nach Übergang auf Sondierung war ein problemloser Kostaufbau möglich. Es bestand der Verdacht auf eine Larynxspalte oder oesophago-tracheale Fistel.Befunde: Röntgen-Thorax: keine pneumonischen Infiltrate, kein Pleuraerguss, Röntgen-Oesophagus-Breischluck: Oesophago-tracheale Fistel (H-Typ), Phoniatrischer Befund: Stimmlippen weiß, glatt, seitengleich beweglich, bei Phonation dichter Schluss, Arytenoidregion bds. deutliche Rötung, Epiglottis regelrecht, keine Residuen von Speichel, geringe Milchrückstände als einzelne Fäden,Schluckreflex auslösbar, Logopädischer Befund: bei Stimulation sofort kräftiges, physiologisches Saug-Schluckmuster, Phonation danach nicht brodlig, Mundmotorik unauffällig, Speichel wird offensichtlich abgeschluckt, Sonografie Schädel und Nieren, ableitende Harnwege o. B., Echokardiografie: kleines PFO, noch offener Ductus arteriosus, Tracheobronchoskopie und Oesophaguskopie: hohe oesophago-tracheale Fistel.Therapie: Es erfolgte der operative Verschluss der 3 mm großen, ca. 1 cm oberhalb der oberen Thoraxaperatur gelegenen oesophago-trachealen Fistel.Fazit: Bei Schluckstörungen im Neugeborenenalter sollte differentialdiagnostisch auch an eine Larynxspalte oder eine oesopgago-tracheale Fistel gedacht werden