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Glucocorticoids, steroid hormones of the adrenal gland, are an integral part of the stress response and regulate glucose metabolism. Natural and synthetic glucocorticoids are widely used in anti-inflammatory therapy but can have severe side effects. In vivo tests are needed to identify novel glucocorticoids and to screen compounds for unwanted effects on glucocorticoid signaling. We created the Glucocorticoid Responsive In vivo Zebrafish Luciferase activitY assay to monitor glucocorticoid signaling in vivo. The GRIZLY assay detects stress-induced glucocorticoid production in single zebrafish larvae, measures disruption of glucocorticoid signaling by an organotin pollutant metabolite, and specifically identifies a compound stimulating endogenous glucocorticoid production in a chemical screen. Our assay has broad applications in stress research, environmental monitoring, and drug discovery.

P. aeruginosa living in biofilm populations sends out diffusive signalling molecules, called autoinducers, for example acylated homoserine lactone (AHL) or the P. aeruginosa quinolone signal (PQS). So far, two quorum-sensing systems, LasR and VsmR, have been identified in P. aeruginosa, both of which are required for all virulence determinants. The expression of specific genes involved in quorum-sensing regulatory mechanisms has been analysed with molecular biology methods. Real-time quantitative PCR is a highly sensitive and powerful technique for quantification of nucleic acids. Expression of the genes vsmR, lasI, and PA4296 was studied by use of reverse transcriptase and subsequent quantitative real-time PCR of the cDNAs. In parallel, expression of ribosomal 16S rRNA, used as a housekeeping gene that was constitutively expressed in all analyses, was also monitored. Biofilm was compared with planktonic bacteria, and in contrast to vsmR and Pa4296, the lasI gene was found to be down-regulated in biofilm. Extended experiments were run with synthetic signal molecules inducing regulated processes in bacterial populations. It was shown that the genes under investigation were up-regulated in mature biofilm in the presence of the signal molecule N-(3-oxododecanoyl)-L-homoserine lactone.

A capillary electrophoresis-electrospray ionisation time-of-flight mass spectrometry (CE-ESI-TOF-MS) method for characterisation of non-covalent protein complexes is described using a coaxial liquid sheath-flow sprayer. The CE capillary was connected to the mass spectrometer using a commercial CE-MS sprayer mounted on a ceramic holder of the ESI interface of the mass spectrometer. Using myoglobin (Mb) as an example of non-covalent protein complex, the effect on complex stability caused by organic modifiers added to the sheath liquid was analysed. Depending on the amount of methanol, either intact Mb or the apoprotein and the prosthetic heme group were detected.

The wide variety of known and unknown endocrine disruptors demands highly efficient methods for detecting the relevant endocrine disrupting pollutants. Bioeffects-related analysis is expected to solve this problem, combining biomolecular recognition processes with chemical analysis, which therefore reduces costs of instrumental chemical analysis to relevant samples. The hyphenation of both steps provides information on potential bioeffects, structure and concentration of the substances of interest. In this work the hyphenation of an enzyme-linked receptor assay (ELRA) with liquid chromatography-tandem mass spectrometry (LC-MSMS) for the analysis of estrogens and xenoestrogens is proposed. Both test systems have been validated with standards and spiked real water samples. The ELRA achieved a detection limit of 0.1 μg/L for 17β-estradiol (without preconcentration). With the LC-MSMS method, steroids could be detected down to 1 ng/L (with preconcentration). Two concepts for a tighter hyphenation of biomolecular interaction and chemical analysis are discussed: the on-line coupling of receptor-affinity chromatography (RAC) to LC-MSMS and the direct measurement of receptor-ligand complexes by LC-MSMS.

During the last few decades, increasing interest in biological surfactants led to an intensification of research for the cost-efficient production of biosurfactants compared with traditional petrochemical surface-active components. The quest for alternative production strains also is associated with new demands on biosurfactant analysis. The present paper gives an overview of existing analytical methods, based on the example of rhamnolipids. The methods reviewed range from simple colorimetric testing to sophisticated chromatographic separation coupled with detection systems like mass spectrometry, by means of which detailed structural information is obtained. High-performance liquid chromatography (HPLC) coupled with mass spectrometry currently presents the most precise method for rhamnolipid identification and quantification. Suitable approaches to accelerate rhamnolipid quantification for better control of biosurfactant production are HPLC analysis directly from culture broth by adding an internal standard or Fourier transform infrared attenuated total reflectance spectroscopy measurements of culture broth as a possible quasi-online quantification method in the future. The search for alternative rhamnolipid-producing strains makes a structure analysis and constant adaptation of the existing quantification methods necessary. Therefore, simple colorimetric tests based on whole rhamnolipid content can be useful for strain and medium screening. Furthermore, rhamnolipid purification from a fermentation broth will be considered depending on the following application.