A new sea cow record from the lower Oligocene of western Germany: new indications on the skeletal morphology of Halitherium schinzii (Mammalia: Sirenia)

Since the discovery of the extinct species Halitherium schinzii in the Mainz Basin, sirenian remains from the German Oligocene are usually assigned to this taxon according to the assumption that this would be the only sea cow species there. The attempts of several authors to determine morphological distinctions on the species level remain unconsidered until today. The new find of a partial sea cow skeleton from the lower Oligocene of Bottrop-Kirchheller Heide (western Germany) stirs up the debate on splitting the species currently referred to as H. schinzii. The Bottrop specimen morphologically corresponds to skullcaps from the Mainz Basin and the Belgian Oligocene, which were the basis for the introduction of new species in the past, but are considered synonymous with H. schinzii today. Despite its fragmentary preservation, the new sirenian record reveals shared morphological features mainly referring to the supraoccipital, such as a distinctly rostrad indenting nuchal crest and a reduced external occipital protuberance. These features are in contrast to the prominent morphology of the specimens generally associated with H. schinzii and support the assumed presence of at least two morphotypes in the Oligocene of Central Europe. Additionally, the sea cow from Bottrop-Kirchheller Heide represents the first occurrence of skeletal elements, which are not preserved in the known specimens from this morphotype so far and may contribute to a better understanding of intra- and/or interspecific differences within Sirenia.     

Towards a comprehensive picture of alloacceptor tRNA remolding in metazoan mitochondrial genomes

Remolding of tRNAs is a well-documented process in mitochondrial genomes that changes the identity of a tRNA. It involves a duplication of a tRNA gene, a mutation that changes the anticodon and the loss of the ancestral tRNA gene. The net effect is a functional tRNA that is more closely related to tRNAs of a different alloacceptor family than to tRNAs with the same anticodon in related species. Beyond being of interest for understanding mitochondrial tRNA function and evolution, tRNA remolding events can lead to artifacts in the annotation of mitogenomes and thus in studies of mitogenomic evolution. Therefore, it is important to identify and catalog these events. Here we describe novel methods to detect tRNA remolding in large-scale data sets and apply them to survey tRNA remolding throughout animal evolution. We identify several novel remolding events in addition to the ones previously mentioned in the literature. A detailed analysis of these remoldings showed that many of them are derived from ancestral events.     

Selective binding of lectins to normal and neoplastic urothelium in rat and mouse bladder carcinogenesis models

Bladder cancer adjuvant intravesical therapy could be optimized by more selective targeting of neoplastic tissue via specific binding of lectins to plasma membrane carbohydrates. Our aim was to establish rat and mouse models of bladder carcinogenesis to investigate in vivo and ex vivo binding of selected lectins to the luminal surface of normal and neoplastic urothelium. Male rats and mice were treated with 0.05 % N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in drinking water and used for ex vivo and in vivo lectin binding experiments. Urinary bladder samples were also used for paraffin embedding, scanning electron microscopy and immunofluorescence labelling of uroplakins. During carcinogenesis, the structure of the urinary bladder luminal surface changed from microridges to microvilli and ropy ridges and the expression of urothelial-specific glycoproteins uroplakins was decreased. Ex vivo and in vivo lectin binding experiments gave comparable results. Jacalin (lectin from Artocarpus integrifolia) exhibited the highest selectivity for neoplastic compared to normal urothelium of rats and mice. The binding of lectin from Amaranthus caudatus decreased in rat model and increased in mouse carcinogenesis model, indicating interspecies variations of plasma membrane glycosylation. Lectin from Datura stramonium showed higher affinity for neoplastic urothelium compared to the normal in rat and mouse model. The BBN-induced animal models of bladder carcinogenesis offer a promising approach for lectin binding experiments and further lectin-mediated targeted drug delivery research. Moreover, in vivo lectin binding experiments are comparable to ex vivo experiments, which should be considered when planning and optimizing future research.