Laser-induced remote release in vivo in C. elegans from novel silver nanoparticles-alginate hydrogel shells

Non-destructive, controllable, remote light-induced release inside cells enables studying time- and space-specific processes in biology. In this work we demonstrate the remote release of tagged proteins in Caenorhabditis elegans (C. elegans) worms using a near-infrared laser light as a trigger from novel hydrogel shells functionalized with silver nanoparticles responsive to laser light. A new type of hydrogel shells was developed capable of withstanding prolonged storage in the lyophilized state to enable the uptake of the shell by worms, which takes place on an agar plate under standard culture conditions. Uptake of the shells by C. elegans was confirmed using confocal laser scanning microscopy, while release from alginate shells in C. elegans and the laser effect on the shells on a substrate in air was followed using fluorescence microscopy. In addition, Raman microscopy was used to track the localization of particles to avoid the influence of autofluorescence. Hierarchical cluster spectral analysis is used to extract information about the biochemical composition of an area of a nematode containing the hydrogel shells, whose Raman signal is enhanced by the SERS (Surface Enhanced Raman Scattering) effect due to hot spots formed by silver nanoparticles present in the shells. The in vivo release demonstrated here can be used to study intestinal microbiota and probiotic compounds as well as a possible future strategy for gene delivery in the worms, other insects and other organisms.

A redox signalling globin is essential for reproduction in Caenorhabditis elegans

Moderate levels of reactive oxygen species (ROS) are now recognized as redox signalling molecules. However, thus far, only mitochondria and NADPH oxidases have been identified as cellular sources of ROS in signalling. Here we identify a globin (GLB-12) that produces superoxide, a type of ROS, which serves as an essential signal for reproduction in C. elegans. We find that GLB-12 has an important role in the regulation of multiple aspects in germline development, including germ cell apoptosis. We further describe how GLB-12 displays specific molecular, biochemical and structural properties that allow this globin to act as a superoxide generator. In addition, both an intra- and extracellular superoxide dismutase act as key partners of GLB-12 to create a transmembrane redox signal. Our results show that a globin can function as a driving factor in redox signalling, and how this signal is regulated at the subcellular level by multiple control layers.

Effects of the antibiotic tetracycline on the reproduction, growth and population growth rate of the nematode Caenorhabditis elegans

The antibiotic tetracycline (TC) has been reported in natural systems, a consequence of its abundant usage in farming. TCs are protein synthesis inhibitors that are effective against bacteria but adverse effects on non-target organisms, whilst less well understood, have also been demonstrated. This study is the first investigation into the effects of this common antibiotic on the growth, reproduction and population growth rate (PGR) of the nematode Caenorhabditis elegans. All toxicological endpoints were shown to be affected negatively. TC concentrations as low as 5 mg l−1 (5 ppm) significantly reduced growth and reproduction, and even lower concentrations (3 mg l−1 or 3 ppm) significantly decreased the PGR. These levels are much higher than the TC concentrations detected in surface waters, sediments and soils (0.005-300 ppb). However, although the antibiotic might not pose a direct significant risk to nematodes in the natural environment, its use in RNAi experiments involving C. elegans may cause unwanted effects that influence interpretations of the results.