BIOspektrum Fernstudium

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Hier finden Sie "Appetithäppchen" aus dem aktuellen BIOspektrum-Heft.


Chloroplasten-Proteinbiogenese: angepasst an das phototrophe Leben

 (S. 127)
Lisa Désrée Westrich, Vincent Leon Gotsmann, Felix Willmund

Chloroplasts possess a small genome which encodes for many essential complex subunits involved in photosynthesis. The integration of these proteins together with nucleus-encoded and posttranslationally imported proteins into a functional chloroplast proteome is a major challenge which is regulated on multiple levels. Here, we highlight unique features of the chloroplast protein biogenesis machinery and their roles during plant acclimation to environmental changes.

Erwachen aus der Chlorose: Wie scheintote Cyanobakterien ergrünen

 (S. 132)
Karl Forchhammer

Non-diazotrophic cyanobacteria respond to nitrogen starvation by growth arrest and pigment degradation (chlorosis), resulting in dormant cells that are able to survive starvation periods for extended periods of time. Resuscitation from chlorosis by nutrient availability is a developmental process that is supported by a highly organized, genetically determined program.

Freisetzung von Herpesviruskapsiden aus dem Kern

 (S. 138)
Barbara G. Klupp, Sebastian Rönfeldt, Thomas C. Mettenleiter

Herpesvirus nucleocapsids are formed in the nucleus but mature into virions in the cytoplasm. Canonical nucleo-cytoplasmic transport is restric - ted to the nuclear pore which is too small for passage of the ca. 120 nm nucleocapsid. Therefore, herpesviruses use a special, vesicle-mediated transfer by budding of nucleocapsids at the inner nuclear membrane involving a heterodimeric viral protein complex followed by fusion with the outer nuclear membrane. A similar cellular mechanism might exist allowing other large cargo to leave the nucleus.

Vaters Ernährung beeinflusst seine Spermienqualität

 (S. 142)
Klaus Steger

Our daily food, especially vitamins of the B-family and secondary plant metabolites, have the potential to modify epigenetic signatures, which are located on both our DNA and associated histones. These bioactive substances play an important role in activating and silencing gene expression and, therefore, represent a bridge between nutrition and health. Modified epigenetic signatures in our germ cells, e. g. caused by obesity, may even be inherited to our children and grandchildren and have the potential to affect health in their later life.

Menschliche T-Zellen reagieren auf CRISPR-assoziierte Nukleasen

 (S. 146)
Dimitrios L. Wagner, Michael Schmueck-Henneresse

CRISPR-Cas genome editing enables precise modification of human DNA in living cells. The technology was adapted from a mechanism by which bacteria protect themselves from viruses. Previous exposure to these bacteria can sensitize human immune cells to Cas proteins. Preexisting antibodies and T cells directed toward Cas antigens warrant a careful evaluation during clinical application of CRISPR-Cas gene therapy in vivo. Here, we summarize recent evidence on Cas-directed T cell immunity in humans and discuss the implications for the clinical translation of the technology.

Das stressige Leben des Bacillus subtilis

 (S. 150)
Ingo Hantke, Heinrich Schäfer, Regina Kramer, Kürsad Turgay

Here we present Bacillus subtilis as a model system to study protein homeostasis and protein quality control in conjunction with the different layers of its stress response systems. We established a new marker to study protein aggregation in vivo. Furthermore, we observed that the transcription factor Spx, which has already been characterized as a central player to activate transcription of redox-chaperones during heat shock and oxidative stress response, was also able to simultaneously inhibit the transcription of translation-related genes as a second response to stress.

Sekretion von Galektin-3 – Blaupause für die Freisetzung behüllter Viren?

 (S. 153)
Ralf Jacob, Sebastian Bänfer

In the classical view secreted proteins are synthesized at the ER and traverse the Golgi before being released into the extracellular medium at the cell surface. However, substantial number of polypeptides utilize alternative non-classical secretion following initial synthesis in the cytoplasm. Among them is galectin-3, which mediates numerous physiological functions in the extracytosolic milieu. Here, we discuss the molecular mechanism by which galectin-3 enters exosomes for secretion in association with the ESCRT-component Tsg101.

Computergestütztes Design mikrobieller Zellfabriken

 (S. 156)
Steffen Klamt, Axel von Kamp, Björn-Johannes Harder

A key principle for the rational design of cell factories is the stoichio - metric coupling of growth and product synthesis. Based on this approach we recently constructed an Escherichia coli strain producing itaconic acid with excellent yields. Furthermore, in a large-scale computational study we demonstrated that coupling of growth and production is, in principle, feasible for almost all metabolites in five major production organisms. These results are of fundamental importance for rational metabolic engineering in biotechnology.

Sind Ihre Daten normalverteilt?

 (S. 159)
Harald Seitz, Christian J. Raue, Sandra Mükusch

For statistical evaluation a normal distribution of the data is often necessary and essential. Parametric tests require values like arithmetic mean and standard deviation (sd) and therefor a normal distribution. They are often way more precise compared to non-parametric ones. That’s why one should always check whether the data features a normal distribution. If that is not the case a robust method is to use only non-parametric tests but there is also a way to make use of parametric tests. For this purpose, data transformation can be applied to achieve normality.

Hitze stabilisiert Malariaimpfstoffkandidaten in komplexen Proteinextrakten

 (S. 163)
Johannes Felix Buyel

Plants can be an alternative to mammalian cell cultures in terms of vaccine production due to low upstream production costs and a good safety profile. However, product purification can be challenging because of abundant host cell proteins (HCPs) in raw plant extracts. Here we report the optimization of blanching, a heat-based method, that allowed to remove over 90 percent of HCPs and to stabilize a malaria vaccine candidate by carefully adjusting the temperature in the step and combined it with solid-liquid separation and chromatographic purification.

Massenspektrometrische Analyse von Phospholipiden aus Liposomen

 (S. 167)
Melissa Frick, Carla Schmidt

Mass spectrometry-based lipidomics gained importance and nowadays allows the identification of complete lipidomes. Challenging are, however, the differing properties of the diverse lipid classes. Phospholipids are the main constituents of biological membranes and, in aqueous solutions, spontaneously form lipid bilayers. They are therefore often used to prepare membrane mimics. Here, we report on a recent strategy identifying and quantifying phospholipids from the lipid bilayer of liposomes.

Einzelmolekül-Lokalisationsmikroskopie mit mikrobiellen Proben

 (S. 170)
Marc Bramkamp, Helge Feddersen, Jae Y. Shin

Super-resolution microscopy visualizes cellular components near their macromolecular scale (∼ 20 nm) and allows one to access structural and functional information within cells. This microscopy has been particularly valuable to unveil new biological insights in the field of bacterial cell biology, where the tiny size of bacterial cells imposed long-standing challenges to visualize cellular components. Here, we report a workflow to image bacterial cellular components with photoactivated localization microscopy that involves experimental design, sample preparation, data acquisition and analysis.

Anwendungen & Produkte

GPCR-Aktivierung: Live-Berichterstattung aus der Zelle

 (S. 186)
Andrea Krumm

Live cell assays with genetically encoded, fluorescent biosensors provide significant advantages over endpoint assays in cell lysates as they acquire the timing of cellular responses in cells relevant to disease. Here we show how second messengers relevant to the Gs/Gi or the Gq signalling pathway are detected in living cells using assays for cAMP, diacylglycerol (DAG), and Ca2+.


Quantifizierungsmethoden für die Produktion von PHB mittels Halomonas halophila

 (S. 226)
Birgit Kamm, Raphaela Süss, Viktoria Leitner, Christina Paulik, Robert Putz

The quantification of polyhydroxybutyrate (PHB) in biomass of Halomonas halophila was compared using different methods (TGA, GC-FID, GC-MS, HPLC). The determined PHB contents were similar in all applied methods. The observed differences between washed and unwashed samples are discussed. Basically, the time required to determine the final results is significantly different by the methods used. With regard to the total analysis time, the application of the TGA is the method of choice.



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Hochauflösende Methoden, z. B. die massenspektrometrische Proteomik oder die in vivo-Mikrokopie, sind mittlerweile so präzise, dass eine optimale Qualität der Proben für valide Ergebnisse unerlässlich ist. Gerade bei Versuchen mit heterogenen Proben, empfindlichen Zellbestandteilen oder auch in der Bioproduktion von pharmazeutischen Produkten ist die Probenvorbereitung ein entscheidender Schritt, der die Qualität, Zuverlässigkeit und Reproduzierbarkeit der Ergebnisse maßgeblich beeinflusst. (Hintergrundbild: © kwanchaift/

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