Kantonsschule Zug

The sea anemone, Exaiptasia diaphana, previously known as Exaiptasia pallida or Aiptasia pallida, has become increasingly popular as a model for cnidarian-microbiome symbiosis studies due to its relatively rapid growth, ability to reproduce sexually and asexually, and symbiosis with diverse prokaryotes and the same microalgal symbionts (family Symbiodiniaceae) as its coral relatives. Clonal E. diaphana strains from Hawaii, the Atlantic Ocean, and Red Sea are now established for use in research. Here, we introduce Great Barrier Reef (GBR)-sourced E. diaphana strains as additions to the model repertoire. Sequencing of the 18S rRNA gene confirmed the anemones to be E. diaphana while genome-wide single nucleotide polymorphism analysis revealed four distinct genotypes. Based on Exaiptasia-specific inter-simple sequence repeat (ISSR)-derived sequence characterized amplified region (SCAR) marker and gene loci data, these four E. diaphana genotypes are distributed across several divergent phylogenetic clades with no clear phylogeographical pattern. The GBR E. diaphana genotypes comprised three females and one male, which all host Breviolum minutum as their homologous Symbiodiniaceae endosymbiont. When acclimating to an increase in light levels from 12 to 28 μmol photons m−2 s−1, the genotypes exhibited significant variation in maximum quantum yield of Symbiodiniaceae photosystem II and Symbiodiniaceae cell density. The comparatively high levels of physiological and genetic variability among GBR anemone genotypes make these animals representative of global E. diaphana diversity and thus excellent model organisms. The addition of these GBR strains to the worldwide E. diaphana collection will contribute to cnidarian symbiosis research, particularly in relation to the climate resilience of coral reefs.

We develop a method to enable collaborative modelling of gravitational lenses and lens candidates, that could be used by non-professional lens enthusiasts. It uses an existing free-form modelling program (glass), but enables the input to this code to be provided in a novel way, via a user-generated diagram that is essentially a sketch of an arrival-time surface. We report on an implementation of this method, SpaghettiLens, which has been tested in a modelling challenge using 29 simulated lenses drawn from a larger set created for the Space Warps citizen science strong lens search. We find that volunteers from this online community asserted the image parities and time ordering consistently in some lenses, but made errors in other lenses depending on the image morphology. While errors in image parity and time ordering lead to large errors in the mass distribution, the enclosed mass was found to be more robust: the model-derived Einstein radii found by the volunteers were consistent with those produced by one of the professional team, suggesting that given the appropriate tools, gravitational lens modelling is a data analysis activity that can be crowd-sourced to good effect. Ideas for improvement are discussed; these include (a) overcoming the tendency of the models to be shallower than the correct answer in test cases, leading to systematic overestimation of the Einstein radius by 10 per cent at present, and (b) detailed modelling of arcs.

Genetic mapping with DNA sequence polymorphisms allows for map-based positional cloning of mutations at any required resolution. Numerous methods have been worked out to assay single nucleotide polymorphisms (SNPs), the most common type of molecular polymorphisms. However, SNP genotyping requires customized and often costly secondary assays on primary PCR products. Small insertions and deletions (InDels) are a class of polymorphisms that are ubiquitously dispersed in eukaryotic genomes and only about fourfold less frequent than SNPs. InDels can be directly and universally detected as fragment length polymorphisms (FLPs) of primary PCR fragments, thus eliminating the need for an expensive secondary genotyping protocol. Genetic mapping with FLPs is suited for both small-scale and automated high-throughput approaches. Two techniques best suited for either strategy and both offering very high to maximal fragment-size resolution are discussed: Analysis on nondenaturing Elchrom gels and on capillary sequencers. Here, we exemplify FLP-mapping for the model organisms Drosophila melanogaster and Caenorhabditis elegans. FLP-mapping can, however, be easily adapted for any other organism as the molecular biology involved is universal. Furthermore, we introduce FLP mapper, a JAVA-based software for graphical visualization of raw mapping data from spreadsheets. FLP mapper is publicly available at http://bio.mcsolutions.ch.