Home • Encephalitozoon romaleae SJ-2008
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Phylogenetic tree of Microsporidia including E. romaleae.

The genome sequence and gene predictions of Encephalitozoon romaleae were not determined by the JGI, but were downloaded from NCBI and have been published (Jean-François Pombert, Mohammed Selmanb, Fabien Burki et al., 2012). Please note that this copy of the genome is not maintained by the author and is therefore not automatically updated.

Microsporidia are highly derived relatives of fungi that are obligate intracellular parasites of virtually all animal lineages and which lead to a number of economically and medically important diseases, particularly in sericulture and apiculture. To date, more than 1,200 microsporidian species have been described, and at least 13 of these species infect humans; many are opportunistic pathogens found in immune-compromised patients. The group is distinguished by a number of cellular characteristics, including the presence of a specialized host-invasion apparatus (the polar tube), an unconventional Golgi apparatus, and highly reduced mitochondria called "mitosomes".

The smallest (nonorganellar) nuclear genomes currently known are those of microsporidian species in the genus Encephalitozoon, making them a model for extreme reductive forces in nuclear genome evolution. Complete genome sequences from two species were found to encode about 2,000 genes making up a reduced set of sometimes simplified molecular and biochemical pathways. Their high degree of host dependence also is reflected in the relatively large number of transporters encoded in these genomes (e.g., ATP transporters), which allow them to acquire essential energy and nutrients from their hosts. Some of these transporters are thought to have originated by horizontal gene transfer (HGT), possibly from coexisting bacterial pathogens, and the recent finding of an animal-derived gene in both Encephalitozoon romaleae and Encephalitozoon hellem also raised the intriguing possibility that microsporidia can acquire genes from their hosts.

 

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