Die Verbreitung vonJuncus tenuis Willd. in Mähren und Schlesien

Ohne Zusammenfassung     

Untersuchungen über Nitritbakterien

Ohne Zusammenfassung     

A subcomplex of human mitochondrial RNase P is a bifunctional methyltransferase—extensive moonlighting in mitochondrial tRNA biogenesis

Transfer RNAs (tRNAs) reach their mature functional form through several steps of processing and modification. Some nucleotide modifications affect the proper folding of tRNAs, and they are crucial in case of the non-canonically structured animal mitochondrial tRNAs, as exemplified by the apparently ubiquitous methylation of purines at position 9. Here, we show that a subcomplex of human mitochondrial RNase P, the endonuclease removing tRNA 5′ extensions, is the methyltransferase responsible for m¹G9 and m¹A9 formation. The ability of the mitochondrial tRNA:m¹R9 methyltransferase to modify both purines is uncommon among nucleic acid modification enzymes. In contrast to all the related methyltransferases, the human mitochondrial enzyme, moreover, requires a short-chain dehydrogenase as a partner protein. Human mitochondrial RNase P, thus, constitutes a multifunctional complex, whose subunits moonlight in cascade: a fatty and amino acid degradation enzyme in tRNA methylation and the methyltransferase, in turn, in tRNA 5′ end processing.     

Multi-copy expression and fed-batch production of Rhodotorula araucariae epoxide hydrolase in Yarrowia lipolytica

Epoxide hydrolases (EHs) of fungal origin have the ability to catalyze the enantioselective hydrolysis of epoxides to their corresponding diols. However, wild type fungal EHs are limited in substrate range and enantioselectivity. Additionally, the production of fungal epoxide hydrolase (EH) by wild-type strains is typically very low. In the present study, the EH-encoding gene from Rhodotorula araucariae was functionally expressed in Yarrowia lipolytica, under the control of a growth phase inducible hp4d promoter, in a multi-copy expression cassette. The transformation experiments yielded a positive transformant, with a final EH activity of 220 U/g dw in shake-flask cultures. Evaluation of this transformant in batch fermentations resulted in ~ 7-fold improvement in EH activity over the flask scale. Different constant specific feed rates were tested in fed-batch fermentations, resulting in an EH activity of 1,750 U/g dw at a specific feed rate of ~ 0.1 g/g/h, in comparison to enzyme production levels of 0.3 U/g dw for the wild type R. araucariae and 52 U/g dw for an Escherichia coli recombinant strain expressing the same gene. The expression of EH in Y. lipolytica using a multi-copy cassette demonstrates potential for commercial application.     

Systematic embryology of the Scilla siberica alliance (Hyacinthaceae)

Eleven species of the Scilla siberica alliance, a well defined monophyletic group within the "genus by tradition" Scilla , have been investigated embryologically with special reference to embryo sac and endosperm development. Data are now available for 15 out of 20 known species. In most species embryo sacs develop according to the bisporic Allium-type, only in Scilla rosenii according to the tetrasporic Drusa-type. Endosperm development is either nuclear or helobial (in 10 and 4 species respectively, unknown in 1). The taxonomic significance of these traits is evaluated after character polarisation by out-group comparison. Among the out-group taxa, S. persica may be considered as the sister group of the S. siberica alliance because only these two groups have an Allium-type embryo sac, a synapomorphy derived from the plesiomorphic Polygonurn-type. The Drusa-type in S. rosenii is an autapomorphy for that species and evolved from an Allium-type embryo sac. S. rosenii is distinct from its sister species S. koenigii , previously thought to be conspecific. Nuclear endosperm is considered to be plesiomorphic rather than apomorphic within the S. siberica alliance, with respect to its occurrence in the presumed sister group and other outgroup taxa (S. hohenackeri group, S. bifolia alliance), but some doubt remains because of a helobial endosperm occurring in the out-group taxon S. messeniaca . The distribution of other synapomorphies within the S. siberica alliance suggests that a helobial endosperm evolved as a synapomorphy for S. bithynica, S. melaina and S. mischtschenkoana , but as a parallel trait in S. leepii . Species status for S. leepii is supported.     

The presence of a haloarchaeal type tyrosyl-tRNA synthetase marks the opisthokonts as monophyletic

Lateral gene transfer plays an important role in the evolution of life. Events of ancient gene transfer can transmit genetic novelties to descendent lineages and subsequently shape their genetic systems. We here present the analyses of the gene encoding tyrosyl-tRNA synthetase (tyrRS), which reveal two eukaryotic tyrRS lineages, one including the opisthokonts and the other the remaining eukaryotes. The different origins of tyrRS lineages between the opisthokonts and the remaining eukaryotes indicate a likely case of ancient lateral gene transfer of tyrRS from an archaeon to the opisthokonts, which lends further support for the monophyly of the latter group. Ancient paralogy followed by differential gene loss is an alternative, albeit less parsimonious explanation for the distribution of the two eukaryotic tyrRS types. In either case, the presence of a haloarchaeal tyrRS type in the opisthokonts marks this group as monophyletic. This finding also points to the potential utility of ancient gene transfer events as molecular markers for major organismal lineages.     

Structurally and functionally unique complexins at retinal ribbon synapses

Ribbon synapses in retinal sensory neurons maintain large pools of readily releasable synaptic vesicles. This allows them to release several hundreds of vesicles per second at every presynaptic release site. The molecular components that cause this high transmitter release efficiency of ribbon synapses are unknown. In the present study, we identified and characterized two novel vertebrate complexins (CPXs), CPXs III and IV, that are the only CPX isoforms present in retinal ribbon synapses. CPXs III and IV are COOH-terminally farnesylated, and, like CPXs I and II, bind to SNAP receptor complexes. CPXs III and IV can functionally replace CPXs I and II, and their COOH-terminal farnesylation regulates their synaptic targeting and modulatory function in transmitter release. The novel CPXs III and IV may contribute to the unique release efficacy of retinal sensory neurons.     

Molecular simulation of adsorption from dilute solutions

Adsorption of biomolecules on surfaces is a perennial and general challenge relevant to many fields in biotechnology. A change of the Helmholtz free energy DeltaA takes place when a molecule becomes adsorbed out of a bulk solution. The purpose of our investigations is to explore routes for the calculation of DeltaA by molecular simulations. DeltaA can be obtained both by integration over the mean force on a molecule and via the local density. It turns out that the route via the potential of mean force prevails over the latter due to better consistency. In this work we present results for systems of 1-centre and 2-centre Lennard-Jones mixtures at a 9/3 Lennard-Jones wall.