Secret sex life of killer fungus?

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Secret sex life of killer fungus?Aspergillus fumigatus is a medically important

fungus, causing potentially life-threatening infections in patients with

weakened immune systems. It is also a major cause of respiratory allergy, and it

is implicated in asthma as well. The fungus has always been thought to lack the

ability to reproduce sexually, but new discoveries by a multinational group of

scientists indicate that the fungus has a number of characteristics of sex. The

possible presence of sex in the species is highly significant because it may

affect the way researchers study--and try to control--disease associated with

the fungus.

The team, headed by Dyer at the University of Nottingham (UK), with lead

researchers Mathieu Paoletti (University of Nottingham, UK) and Carla Rydholm

(Duke University, USA), used a number of techniques to study the fungus. The

genome of Aspergillus fumigatus has recently been sequenced, and investigation

of the genome revealed the presence of a series of genes required for sexual

reproduction.

In the new study, the researchers report that the analysis of a worldwide

collection of 290 specimens of the fungus revealed nearly equal proportions of

two different sexes, or " mating types, " which in theory could have sex with each

other. Additional work on specific populations of the fungus in America and

Europe showed that genes had been, or were being, exchanged between individuals

of the fungus--another strong sign of mating. The researchers also showed that

some key genes involved with detecting mating partners were active in the

fungus.

Taken as a whole, the study's results indicate that the fungus has a recent

evolutionary history of sexual activity and might still be having sex, if thus

far unseen by human eyes. These results are important because if the fungus does

reproduce sexually as part of its life cycle, it might evolve more rapidly to

become resistant to antifungal drugs used to control disease; sexual

reproduction might lead to new strains with increased ability to cause disease

and infect humans. Nevertheless, the sexual cycle could be a useful genetic tool

for scientists to use in their study of the mechanisms by which the fungus

causes disease. Further work is now aimed at seeing if the fungus can truly

reproduce by sexual means.

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Mathieu Paoletti, Elke U. Schwier, and S. Dyer of the University of

Nottingham; Carla Rydholm and François Lutzoni of Duke University; J.

and W. Denning of University of Manchester; Szakacs of

Technical University of Budapest; and Jean- Debeaupuis and Jean- Latgé

of the Institut Pasteur. This work was supported by the Biotechnology and

Biological Sciences Research Council (United Kingdom), the Wellcome Trust (UK),

the Fungal Research Trust (UK), and Duke University (USA).

Mathieu Paoletti, Carla Rydholm, Elke U Schwier, J ,

Szakacs, Francois Lutzoni, Jean- Debeaupuis, Jean- Latge, W

Denning, Stanley Dyer (2005). Evidence for sexuality in the opportunistic

fungal pathogen Aspergillus fumigatus. DOI 10.1016/j.cub.2005.05.045 Publishing

in Current Biology, Vol. 15, 1242-1248, July 12, 2005. www.current-biology.com

Contact: Heidi Hardman

hhardman@...

1-617-397-2879

Cell Press

http://www.eurekalert.org/pub_releases/2005-07/cp-ssl070605.php