Before going to Stockholm Laura and I picked thousands of glochidia from fish gills at Karlstads University thus sub-samples from different fish individuals and species could be taken to the DNA lab at the Swedish Museum of Natural History. Glochidia originated from fish caught in the Rivers Tommarpsån and Bråån during this year. The main research questions based on host-fish use by Unio crassus in natural conditions i.e. do the mussel glochidia found on fish belong to the species Unio crassus? This also includes the question if there are other mussel species in our rivers that potentially can infest the same fish species as UC and if so which other mussel species do occur? So far, only individuals of the species U.crassus were found in Bråån and Tommarpsån by means of morphological identification. We are all curious what the genetic analyses will bring!
Having arrived in Stockholm I was nicely introduced in the work group of Pia Eldenäs. Great thanks to her and the team! All methods used were shown and explained me with accuracy and great patience step by step thus it was possible to analyze all glochidia-subsamples prepared for DNA analysis. The latter mentioned started with a DNA-extraction using a special robot, followed by PCRs (polymerase chain reactions) and controlling the PCR products by running a gel.
In the following step the PCR products were cleaned and amplified again which led then to the last step: the sequencing. As a result proper DNA-sequences were given by the sequencer. Those could be compared to mussel DNA-sequences listed in the online database BLAST and also to reference sequences owned by the DNA-lab. The final results are still in process, but it can be mentioned that Unio crassus was identified on minnows (Phoxinus phoxinus), bullheads (Cottus gobio) and trouts (Salmo trutta).
It was a very interesting experience to finally combine samples taken during the field work season with genetic lab work which bring us more information about Unio crassus populations in the rivers and their relation to host-fish.