A) Daphnia magna individual infected with Mitosporidium daphniae. B) Multiple vesicles filled with parasite spores. C) Individual parasite spores. [Photo credits: Dieter Ebert]

The genome sequence and gene prediction of Mitosporidium daphniae UPG3 have not been determined by the Joint Genome Institute (JGI), but were downloaded from NCBI on May 28, 2018. In order to allow comparative analyses with other fungal genomes sequenced by the JGI, a copy of this genome is incorporated into Mycocosm. Please note that this copy of the genome is not maintained by NCBI and is therefore not automatically updated. JGI tools were used to automatically annotate predicted proteins.

Mitosporidium daphniae is an obligate endoparasite known only from the lower midgut epithelium of the water flea Daphnia magna in north-western Europe. The species was shown by Dieter Ebert’s lab to have a negative fitness effect on the host (Refardt and Ebert 2012) and was known for a long time as unknown gut parasite 3 (UGP3) because of its uncertain phylogenetic affinities. Morphologically the species is similar to the highly reduced Microsporidia endoparasites, but has a minimal polar tube (infection structure) relative to core Microsporidia. Initially, rRNA gene sequences allied the parasite with the enigmatic group of fungi related to Microsporidia known as Cryptomycota (or Rozellids or Rozellomycota) that are by and large only known from environmental DNA sequences (Richards et al. 2017). Haag et al. (2014) sequenced the genome of M. daphniae and found that it is contains similarities to both Rozella allomycis (Cryptomycota), such as ability to generate energy through oxidative phosphorylation and a very similar mitochondrial genome. On the other hand, M. daphniae has considerably fewer genes than R. allomycis and has reduced DNA repair and recombination proteins and an elevated rate of nucleotide substitution as observed in core Microsporidia. M. daphniae is variously considered as a Cryptomycotan or Microsporidian, and it is clear that the lines between these two groups are blurred because of species like M. daphniae which possess traits intermediate between both groups (Bass et al. 2018).