Boden – ein unterschätzter Lebensraum

Soil – an underestimated biotope The soil is a biotope with high species abundances and richness. It is, furthermore, a location where important ecosystem services are realized. Recent research projects on the origin and development of soil animal communities, on the heterogeneous interactions within the soil nutrient net and the distribution of soil animals show the different ecological traits and adaptabilities of the world beneath our feet. So research contributes to maintain the eco‐resource of soil and its sustainable use.     

Spatial heterogeneity lowers rather than increases host–parasite specialization

Abiotic environmental heterogeneity can promote the evolution of diverse resource specialists, which in turn may increase the degree of host–parasite specialization. We coevolved Pseudomonas fluorescens and lytic phage ?2 in spatially structured populations, each consisting of two interconnected subpopulations evolving in the same or different nutrient media (homogeneous and heterogeneous environments, respectively). Counter to the normal expectation, host–parasite specialization was significantly lower in heterogeneous compared with homogeneous environments. This result could not be explained by dispersal homogenizing populations, as this would have resulted in the heterogeneous treatments having levels of specialization equal to or greater than that of the homogeneous environments. We argue that selection for costly generalists is greatest when the coevolving species are exposed to diverse environmental conditions and that this can provide an explanation for our results. A simple coevolutionary model of this process suggests that this can be a general mechanism by which environmental heterogeneity can reduce rather than increase host–parasite specialization.     

Widespread Expression of Erythropoietin Receptor in Brain and Its Induction by Injury

Erythropoietin (EPO) exerts potent neuroprotective, neuroregenerative and procognitive functions. However, unequivocal demonstration of erythropoietin receptor (EPOR) expression in brain cells has remained difficult since previously available anti-EPOR antibodies (EPOR-AB) were unspecific. We report here a new, highly specific, polyclonal rabbit EPOR-AB directed against different epitopes in the cytoplasmic tail of human and murine EPOR and its characterization by mass spectrometric analysis of immuno-precipitated endogenous EPOR, Western blotting, immunostaining and flow cytometry. Among others, we applied genetic strategies including overexpression, Lentivirus-mediated conditional knockout of EpoR and tagged proteins, both on cultured cells and tissue sections, as well as intracortical implantation of EPOR-transduced cells to verify specificity. We show examples of EPOR expression in neurons, oligodendroglia, astrocytes and microglia. Employing this new EPOR-AB with double-labeling strategies, we demonstrate membrane expression of EPOR as well as its localization in intracellular compartments such as the Golgi apparatus. Moreover, we show injury-induced expression of EPOR. In mice, a stereotactically applied stab wound to the motor cortex leads to distinct EpoR expression by reactive GFAP-expressing cells in the lesion vicinity. In a patient suffering from epilepsy, neurons and oligodendrocytes of the hippocampus strongly express EPOR. To conclude, this new analytical tool will allow neuroscientists to pinpoint EPOR expression in cells of the nervous system and to better understand its role in healthy conditions, including brain development, as well as under pathological circumstances, such as upregulation upon distress and injury.     

Elemental formula annotation of polar and lipophilic metabolites using (13) C, (15) N and (34) S isotope labelling, in combination with high-resolution mass spectrometry

The unbiased and comprehensive analysis of metabolites in any organism presents a major challenge if proper peak annotation and unambiguous assignment of the biological origin of the peaks are required. Here we provide a comprehensive multi-isotope labelling-based strategy using fully labelled (13) C, (15) N and (34) S plant tissues, in combination with a fractionated metabolite extraction protocol. The extraction procedure allows for the simultaneous extraction of polar, semi-polar and hydrophobic metabolites, as well as for the extraction of proteins and starch. After labelling and extraction, the metabolites and lipids were analysed using a high-resolution mass spectrometer providing accurate MS and all-ion fragmentation data, providing an unambiguous readout for every detectable isotope-labelled peak. The isotope labelling assisted peak annotation process employed can be applied in either an automated database-dependent or a database-independent analysis of the plant polar metabolome and lipidome. As a proof of concept, the developed methods and technologies were applied and validated using Arabidopsis thaliana leaf and root extracts. Along with a large repository of assigned elemental compositions, which is provided, we show, using selected examples, the accuracy and reliability of the developed workflow.     

Expression of the lantibiotic mersacidin in Bacillus amyloliquefaciens FZB42

Lantibiotics are small peptide antibiotics that contain the characteristic thioether amino acids lanthionine and methyllanthionine. As ribosomally synthesized peptides, lantibiotics possess biosynthetic gene clusters which contain the structural gene (lanA) as well as the other genes which are involved in lantibiotic modification (lanM, lanB, lanC, lanP), regulation (lanR, lanK), export (lanT(P)) and immunity (lanEFG). The lantibiotic mersacidin is produced by Bacillus sp. HIL Y-85,54728, which is not naturally competent.

Methodology/Principal Findings

The aim of these studies was to test if the production of mersacidin could be transferred to a naturally competent Bacillus strain employing genomic DNA of the producer strain. Bacillus amyloliquefaciens FZB42 was chosen for these experiments because it already harbors the mersacidin immunity genes. After transfer of the biosynthetic part of the gene cluster by competence transformation, production of active mersacidin was obtained from a plasmid in trans. Furthermore, comparison of several DNA sequences and biochemical testing of B. amyloliquefaciens FZB42 and B. sp. HIL Y-85,54728 showed that the producer strain of mersacidin is a member of the species B. amyloliquefaciens.

Conclusions/Significance

The lantibiotic mersacidin can be produced in B. amyloliquefaciens FZB42, which is closely related to the wild type producer strain of mersacidin. The new mersacidin producer strain enables us to use the full potential of the biosynthetic gene cluster for genetic manipulation and downstream modification approaches.     

Rescue of keratin 18/19 doubly deficient mice using aggregation with tetraploid embryos

We have previously shown that the targeted deletions of both type I keratins (K) 18 and 19 cause lethality by embryonic day (e) 9.5 due to fragility and cytolysis of trophoblast giant cells. The development of the embryo proper appeared to be unaffected and its death was caused by nutrient deficiency. In order to address the function of keratins within the embryo proper, lethality due to extraembryonic tissue failure must be overcome. One approach to rescue doubly deficient embryos is by aggregating knockout embryos with tetraploid wild-type embryos. As a general tool, tetraploid aggregation can be used to rescue embryonic lethality caused by defects in extraembryonic tissues like the placenta, trophoblast or yolk sac. We rescued K18-/- K19-/- embryos until e11.5, using this approach, proving that the loss of the keratin cytoskeleton causes defects in the trophoblast giant cell layer, but has no effect on early development of the embryo proper.     

Improving the levels of essential amino acids and sulfur metabolites in plants

Plants represent the major source of food for humans, either directly or indirectly through their use as livestock feeds. Plant foods are not nutritionally balanced because they contain low proportions of a number of essential metabolites, such as vitamins and amino acids, which humans and a significant proportion of their livestock cannot produce on their own. Among the essential amino acids needed in human diets, Lys, Met, Thr and Trp are considered as the most important because they are present in only low levels in plant foods. In the present review, we discuss approaches to improve the levels of the essential amino acids Lys and Met, as well as of sulfur metabolites, in plants using metabolic engineering approaches. We also focus on specific examples for which a deeper understanding of the regulation of metabolic networks in plants is needed for tailor-made improvements of amino acid metabolism with minimal interference in plant growth and productivity.     

Analysis of the dorsal spinal cord synaptic architecture by combined proteome analysis and in situ hybridization

The proteomic analysis of tissue samples is an analytical challenge, because identified gene products not only have to be assigned to subcellular structures, but also to cell subpopulations. We here report a strategy of combined subcellular proteomic profiling and in situ hybridization to assign proteins to subcellular sites in subsets of cells within the dorsal region of rat spinal cord. With a focus on synaptic membranes, which represent a complex membrane protein structure composed of multiple integral membrane proteins and networks of accessory structural proteins, we also compared different two-dimensional gel electrophoresis systems for the separation of the proteins. Using MALDI mass spectrometric protein identification based on peptide mass fingerprints, we identified in total 122 different gene products within the different synaptic membrane subfractions. The tissue structure of the dorsal region of the spinal cord is complex, and different layers of neurons can be distinguished neuroanatomically. Proteomic data combined with an in situ hybridization analysis for the detection of mRNA was used to assign selected gene products, namely the optical atrophy protein OPA-1, the presynaptic cytomatrix protein KIAA0378/CAST1, and the uncharacterized coiled-coil-helix-coiled-coil-helix domain containing protein 3 (hypothetical protein FLJ20420), to cell subsets of the dorsal area of the spinal cord. Most striking, KIAA0378/CAST1 mRNA was found only sparsely within the dorsal horn of the spinal cord, but highly abundant within the dorsal root ganglion. This finding, combined with the identification of KIAA0378/CAST1 within the synaptic membrane fraction of the spinal cord at the protein level, are consistent with the reported presynaptic localization of CAST, predominantly within the tissue we investigated primarily attributable to primary afferent sensory neurons. Our approach may be of use in broader studies to characterize the proteomes of neural tissue.     

Molecular phylogenetics of the giant genus Croton and tribe Crotoneae (Euphorbiaceae sensu stricto) using ITS and TRNL-TRNF DNA sequence data

Parsimony, likelihood, and Bayesian analyses of nuclear ITS and plastid trnL-F DNA sequence data are presented for the giant genus Croton (Euphorbiaceae s.s.) and related taxa. Sampling comprises 88 taxa, including 78 of the estimated 1223 species and 29 of the 40 sections previously recognized of Croton. It also includes the satellite genus Moacroton and genera formerly placed in tribe Crotoneae. Croton and all sampled segregate genera form a monophyletic group sister to Brasiliocroton, with the exception of Croton sect. Astraea, which is reinstated to the genus Astraea. A small clade including Moacroton, Croton alabamensis, and C. olivaceus is sister to all other Croton species sampled. The remaining Croton species fall into three major clades. One of these is entirely New World, corresponding to sections Cyclostigma, Cascarilla, and Velamea sensu Webster. The second is entirely Old World and is sister to a third, also entirely New World clade, which is composed of at least 13 of Webster's sections of Croton. This study establishes a phylogenetic framework for future studies in the hyper-diverse genus Croton, indicates a New World origin for the genus, and will soon be used to evaluate wood anatomical, cytological, and morphological data in the Crotoneae tribe.