Flechten-Mikrobiom: eine alte Symbiose neu entdeckt(S. 12)
Gabriele Berg, Katharina Riedel, Martin Grube
Symbioses represent a frequent and successful lifestyle on Earth. Recently, bacterial communities were identified as stable, specific, and structurally integrated partners of the classical lichen symbiosis. We found that the diverse microbiota have the ability to contribute multiple aspects to the symbiotic system, including health, growth, and fitness. We deve - loped a model of the symbiosis depicting the functional multi-player network of the participants, and argue that the strategy of functional diversification supports longevity of lichens under extreme conditions.
Killerplasmid-codierte Ribotoxin-RNasen aus Hefen(S. 16)
Raffael Schaffrath, Roland Klassen
Certain yeasts produce toxins encoded by cytoplasmic killer plasmids and kill sibling cells which have lost the killer system. Those retaining it, survive due to an immunity gene. This selection regime is at risk when cytoplasmic DNA is captured in the nucleus, but the killer plasmids have prepared for this via an unusually high A/T bias. In case of nuclear immunity gene transcription, the polyadenylation system recognizes A/T-rich motifs, cleaves the mRNA and prevents immunity expression.
Pax6: Funktionen entlang der rostro-kaudalen Achse des Neuralrohrs(S. 19)
Rosa-Eva Hüttl, Andrea B. Huber
During development of the central nervous system (CNS), proliferation, cell fate designation, and patterning decisions are tightly regulated by interdependent networks of key transcriptional regulators. We propose a novel aspect of how Pax6 not only utilizes its modular structure to perform distinct functions but also employs individual sub-domains, thus generating a new level of complexity for transcriptional regulation by one single transcription factor in dorso-ventral and rostro-caudal neural tube patterning.
Streptomyceten: Relevanz für Ökologie, Medizin und Biotechnologie(S. 22)
Hildgund Schrempf, Ulrich Keller
Streptomycetes are differentiated members of actinobacteria with huge abundance in soils, rhizosphere, and marine sediments. In addition to main roles in a free-living style, they are relevant in multiple interactions and specialized symbioses. Their sophisticated enzyme-repertoire is essential to recycle organic matter in nature and to detoxify harmful compounds. The immense gene pool for an amazing repertoire of bioactive compounds is an outstanding source for drugs to combat diseases.
Mitophagie: die gezielte Entsorgung unerwünschter Mitochondrien(S. 26)
Andreas S. Reichert, Christina Behrendt, Marcel Zimmermann
The selective degradation of mitochondria by autophagy, termed mito - phagy, represents an important process required for cell differentiation and removal of damaged mitochondria. Here we review two principle molecular pathways: receptor-mediated and ubiquitin-mediated mito - phagy. The latter pathway was recently linked to the pathogenesis of Parkinson’s disease in humans. Recent studies show that such a mechanism that is regulated by ubiquitination and deubiquitination also exists in baker’s yeast.
Das kleine Kräftemessen – molekulare Kraftmikroskopie in lebenden Zellen(S. 30)
Andrea Freikamp, Carsten Grashoff
The ability of cells to produce, sense and respond to mechanical forces is central to many developmental and pathophysiological processes. The molecular mechanisms that govern these mechanobiological processes in cells, however, have remained unknown because suitable techniques to measure the involved mechanical forces have been missing. In this article, we review recent advances in the development of force sensing techniques that can be used to measure single piconewton forces across individual proteins in cells.
Neue Impulse für den Protein-Knock-down mit intrabodies(S. 33)
Stefan Dübel, Andrea L. J. Marschall
Intrabodies are recombinant antibody fragments produced inside of a living cell in a way to bind their antigen in that same cell, to interfere with its function. As they strictly work on the protein level, intrabodies allow to bypass disadvantages of gene-targeted knock-out animals and knockdown techniques (RNAi, miRNA and small molecule inhibitors). Recently, a regulated knock-down strength was illustrated in viable VCAM1 knockdown mice.
In 24 Stunden zur Muropeptidstruktur(S. 37)
Daniel Kühner, Ute Bertsche
Within the last 60 years peptidoglycan (PGN) composition of bacteria has been intensively studied by various methods. However, preparation of pure PGN relied on a very time-consuming method. We established a purification protocol which can be completely performed in plastic reaction tubes or even microtiter plates within 24 hours. The muropeptides can be analyzed by reversed phase UPLC-MS, allowing their immediate determination even in high throughput.
Bakterielle Überlebensstrategien – Zellzykluskontrolle als Stressantwort(S. 41)
Kristina Heinrich, Kristina Jonas
The cell cycle is an important physiological process, underlying the proliferation and growth of all living organisms. In bacteria, most research has focused on understanding cell cycle progression under standard growth conditions. However in nature, bacteria are exposed to drastic environmental changes. Recent work shows that bacteria have evolved a variety of mechanisms transducing environmental information into the cell cycle engine to ensure their survival.
Zellen im Zeitraffer – Dynamik der Genexpression in Echtzeit(S. 44)
Dagmar Wirth, Mario Köster
Even in genetically identical cell populations gene expression varies. Time lapse microscopy can track fluorescently labelled proteins in individual cells over time, thereby providing information on dynamic processes such as the onset of transgene expression and changes in the subcellular locali zation. Moreover, by combining various readouts, this method can be employed to uncover complex relations. Here, we describe various approaches for elucidating dynamics of inducible expression systems.
Mikrobiologische Einzelzell-Phänotypencharakterisierung im Mikrochip(S. 48)
Christina Krämer, Dietrich Kohlheyer
Microbes adapt to environmental changes by DNA embedded mechanisms (e. g. resistance) or non-DNA based phenotypical differentiation (e. g. tolerance). Single-cell fluorescence imaging combined with environmental control by microfluidic devices helps to unravel phenotypical changes of single microbial cells in isogenic cell populations. Therefore, the intracellular implementation of fluorescent molecules by genetic modification or dynamic staining is essential for non-invasive live-cell imaging.
Anwendungen & Produkte
CRISPR in der biotechnologischen Forschung und Entwicklung(S. 62)
Ümit Pul, Jörg Mampel, Christian Zurek, Michael Krohn
The discovery of programmable double-stranded DNA specific nucleases derived from the prokaryotic immunity systems CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has opened a new era of genome editing and its applications in industrial biotechnology. Simple reprogramming of the DNA-specificity of CRISPR nucleases by RNAs allows the engineering of novel eukaryotic screening or producer cells through gene knock-out, chromosomal deletion and the regulation of gene expression.
Neue Applikationsfelder für Single-use-Bioreaktoren(S. 96)
Stefan Junne, Peter Neubauer, Anna Maria Marbà-Ardébol
Single-use bioreactor development is – compared to conventional bioreactors – a young field of research. This article aims to describe recent achievements and remaining challenges of single-use bioreactors from the microliter to the cubic meter scale. A focus is put on the application for bacteria, yeast and algae. The various design approaches of single-use bioreactors allow tailored applications to fulfil the different demands considering shear forces, power input, gas mass transfer and mixing time.