The small fungus reproduces sexually when it infects the host

A species of fungus called microsporidia that causes chronic diarrhea in AIDS patients, organ transplant recipients, or travelers has recently been listed as a member of the mushroom family. A research team at Duke University Medical Center has demonstrated that microsporidia are true fungi, it seems that they undergo a form of sexual reproduction in the process of infecting humans and other hosts.

Soo Chan Lee, lead author and postdoctoral researcher in the Department of Molecular Genetics and Microbiology (Duke University), said: 'Microsporidian fungal infection is very difficult to treat because so far we still Not much is known about this common pathogen. Up to 50% of AIDS patients are infected with microsporidian fungi, developing into chronic diarrhea. This fungus is also found in travelers with diarrhea, in children, recipients of organ transplants and the elderly '.

Of the 1,200 microsporidia, more than 10 species infect humans . Identifying them is a difficult task because they cannot exist outside the host cells infected with fungi, they have a very small number of genes but grow very quickly. Duke University scientists have applied two genetic studies to prove that microsporidia thrive from sexual reproduction, and especially have a close relationship with synaptic fungi.

They found that microsprodia has 33 common fungi with 2,000 genes , but not the same genes of other fungi. This genetic signal also shows that microsporidia and synaptic fungi seem to share common ancestors, and are more closely related to other known fungal strains.

In addition, these two types of fungi have the same gene that regulates sex, the same sequence on DNA. Other genes related to sexual reproduction are also present. This suggests that microsporidia may have a reproductive cycle regulated by genetic characteristics, which may require sexual reproduction when infecting the host. According to Lee, the next step is to explore sexual reproduction in other species that could make the infection more serious because they use the host environment and its internal organs as a safe haven for reproduction.

Electron scans of microsporidian gametes with a protruding tube used to insert eukaryotic cells.The gamete will pump the infectious fluid through this tube.(Photo: CDC / NCID / DPD Parasite Image Library)

Interpretation Joseph Heitman - director of the Center for Microbiological Microbiology and Director of Genetic and Genetic Programs at Duke University - said: 'This research has solved the mystery of evolutionary origin as well as the appropriate position of this highly successful pathogen group, and at the same time provides more effective approaches to practical research on pathogens'. The team also conducted research with Duke genetic researchers, including Raphael Valdivia, Alejandro Aballay using cultured cells as C. elegans - a worm they recently discovered in their natural hosts. microsporidia mushroom.

Heitman said: 'This nematode may be an effective way to study microsporidia genetics in living organisms'. The study was published online in Current Biology, and was funded by the National Institute of Allergy and Genetic Diseases under the National Institutes of Health and the Canadian National Health Research Institute.

The authors involved in the study included Nicolas Corradi and Patrick J. Keeling (Canadian Research Institute, Department of Botany, University of British Columbia - Vancouver), Edmond J. Byrnes III (Department of Molecular Genetics and Duke of Duke University, Santiago Torres-Martinez (Department of Genetics and Pathology, Department of Biology, University of Murcia, Spain), and Fred S. Dietrich (Department of Molecular Genetics and Pathogenesis) Duke, Duke Institute of Genomics and Policy Science).

Refer:
Lee et al.Microsporidia Evolved from Ancestral Sexual Fungi.Current Biology, 2008;DOI: 10.1016 / j.cub.2008.09.030