Cysteinolic Acid Is a Widely Distributed Compatible Solute of Marine Microalgae

Phytoplankton rely on bioactive zwitterionic and highly polar small metabolites with osmoregulatory properties to compensate changes in the salinity of the surrounding seawater. Dimethylsulfoniopropionate (DMSP) is a main representative of this class of metabolites. Salinity-dependent DMSP biosynthesis and turnover contribute significantly to the global sulfur cycle. Using advanced chromatographic and mass spectrometric techniques that enable the detection of highly polar metabolites, we identified cysteinolic acid as an additional widely distributed polar metabolite in phytoplankton. Cysteinolic acid belongs to the class of marine sulfonates, metabolites that are commonly produced by algae and consumed by bacteria. It was detected in all dinoflagellates, haptophytes, diatoms and prymnesiophytes that were surveyed. We quantified the metabolite in different phytoplankton taxa and revealed that the cellular content can reach even higher concentrations than the ubiquitous DMSP. The cysteinolic acid concentration in the cells of the diatom Thalassiosira weissflogii increases significantly when grown in a medium with elevated salinity. In contrast to the compatible solute ectoine, cysteinolic acid is also found in high concentrations in axenic algae, indicating biosynthesis by the algae and not the associated bacteria. Therefore, we add this metabolite to the family of highly polar metabolites with osmoregulatory characteristics produced by phytoplankton.

Sexual deception of a beetle pollinator through floral mimicry

Sexual mimicry is a complex multimodal strategy used by some plants to lure insects to flowers for pollination.^1-4 It is notable for being highly species-specific and is typically mediated by volatiles belonging to a restricted set of chemical compound classes.^3,4 Well-documented cases involve exploitation of bees and wasps (Hymenoptera)^5,6 and flies (Diptera).^7-9 Although beetles (Coleoptera) are the largest insect order and are well known as pollinators of both early and modern plants,^10,11 it has been unclear whether they are sexually deceived by plants during flower visits.^12,13 Here we report the discovery of an unambiguous case of sexual deception of a beetle: male longhorn beetles (Chorothyse hessei, Cerambycidae) pollinate the elaborate insectiform flowers of a rare southern African orchid (Disa forficaria), while exhibiting copulatory behavior including biting the antennae-like petals, curving the abdomen into the hairy lip cleft, and ejaculating sperm. The beetles are strongly attracted by (16S,9Z)-16-ethyl hexadec-9-enolide, a novel macrolide that we isolated from the floral scent. Structure-activity studies^14,15 confirmed that chirality and other aspects of the structural geometry of the macrolide are critical for the attraction of the male beetles. These results demonstrate a new biological function for plant macrolides and confirm that beetles can be exploited through sexual deception to serve as pollinators.

[Scintigraphic examinations of sacroiliacal joints in patients with early forms of ankylosing spondylitis]

In contrast to the X-ray examination the scintigraphy of the sacroiliacal joints in the early phase of the ankylosing spondylarthritis allows an evidence to the local processes of bone reconstruction directly depending on their activity. Positive findings of scintigraphy have a high sensitivity and a low specifity. They demand a further differential-diagnostic clarification. In this sense, supplementing the X-ray findings, the scintigraphy brings valuable informations for the early diagnostics of ankylosing spondylarthritis. The radiation exposure of the gonads which is smaller by factor 3 in comparison to the X-ray examination of the pelvis is an essential advantage in the above all young patients. The valuation of the scintigramme must be performed in close connection between clinical rheumatologists and specialists in nuclear medicine. Our results show that longitudinal examinations let expect a further improvement of the evidence.