Microsporidian mitosomes

Microsporidia have structurally and biochemically highly reduced mitochondria.There seems to be no Krebs cycle or electron transport chain.There are no cristae and the mitochondrial genome has been lost. I have been researching how this mitochondrion functions in this highly reduced form.

Left: A heavily infected rabbit kidney cell with microsporidian spores labelled in red. Within intracellular meronts stages, it is possible to see mitosomes stained in green with a fluorescent antibody to a mitochondrial Hsp70 protein.

Right: An electron micrograph of a microsporidian meront inside a rabbit kidney cell. The mitosome is labelled with a gold labelled mitochondrial Hsp70 antibody.

Genomics

Microsporidia genome sizes vary greatly over the phylum, we are currently looking at what accounts for these genome size differences

Phylogeny of microsporidia with known genomes sizes

Microsporidian genes are tighly packed in the genomes, with short spaces separating genes. In some cases, promoter and termination signals seem to be forced into up and downstream genes. This results in messenger RNA transcripts with fragments of surrounding genes in the 5' and 3' untranscribed regions.