Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sex Determining Genes of Infectious Fungus Resemble Human Y Chromosome

11.11.2004


Fungi and animals, including humans, have a lot in common when it comes to the arrangement of genes that determine their sex, according to new work by Howard Hughes Medical Institute geneticists at the Duke University Medical Center.



Regions of the genome that determine the sexual identity of the infectious fungus Cryptococcus neoformans bear striking similarities to the human Y chromosome -- the sex chromosome associated with male characteristics -- the team found. The researchers reported their findings in the December 2004 issue of the Public Library of Science Biology (now available online).

The result suggests that, despite their differences, similar evolutionary processes shaped the chromosomal sex-determining regions in both groups, said HHMI investigator Joseph Heitman, M.D., director of Duke’s Center for Microbial Pathogenesis. The fungus might therefore serve as a useful model system for the study of sex chromosome evolution and the genetic changes that can lead to infertility, he said. "The revolution in genome sciences has rapidly accelerated our ability to elucidate the process by which sex chromosomes evolved," Heitman said. "While mechanisms of sex determination are extremely diverse, our study highlights remarkable similarities among them in widely divergent groups."


The findings might also provide new insight into the process whereby the infectious fungus spurs disease, because evidence suggests a close tie between the genes involved in sexual identity and virulence, Heitman added. The work was supported by the National Institute of Allergy and Infectious Diseases. Sexual identity is governed by sex chromosomes in plants and animals. In humans and other mammals, males have one X and one Y chromosome, while females have a pair of X’s. In fungi, sexual identity is determined by so-called "mating type loci," genes located in a contiguous region of the genome, but which typically do not span an entire chromosome. C. neoformans exists in two mating types determined by a single genetic locus. Earlier work found that this sex-determining region is unusually large in C. neoformans compared to other fungi, containing a series of more than 20 genes.

The researchers reconstructed the sequential evolutionary events that fashioned the sex-determining region of the C. neoformans genome by comparing it to that region in the related pathogenic fungal species, Cryptococcus grubii and Cryptococcus gattii.

The sex-determining genome region appears to have acquired genes in four main steps -- beginning with the acquisition of genes into two separate sex-determining regions that later fused, the team reported. Furthermore, they found that the fungal sex-determining genes exist in clusters of functionally related genes. For example, genes involved in mate recognition occur in tandem, as do those that govern spore production. Other researchers have found that the human Y chromosome -- and the functionally-related gene clusters it contains -- has a similar history, characterized by the "sequential capture of genes" on four separate occasions, Heitman said. The fungal mating type locus later underwent processes that suppress recombination, they found. Recombination is the process whereby each member of a pair of chromosomes exchange segments of DNA. The procedure allows for new gene combinations to form and for the repair of damaged DNA.

The human Y chromosome is also barred from recombination along most of its length, a necessary requirement to prevent genes that encode male traits from infiltrating the female X chromosome, Heitman noted.

The researchers suggest that, despite the lack of recombination, some fungal mating type gene repair might occur through the exchange of gene segments within chromosomes. Certain sex-determination genes occur in palindromic orientations –- head-to-head or tail-to-tail repeats of particular sequences –- which would make such intra-chromosomal repair possible, a pattern also found on the human Y chromosome, according to Heitman. "These similarities suggest that further study of C. neoformans might help elucidate the genetic changes that can lead to infertility in fungi and humans, as well as the repair mechanisms that prevent its more common occurrence," Heitman said.

Their findings might also yield insight into the mechanism whereby C. neoformans invades the central nervous system to cause disease, most commonly in patients who lack a functioning immune system, such as organ transplant recipients and those with HIV/AIDS, Heitman added. A single fungal mating type spurs the vast majority of all C. neoformans infections, he explained, suggesting that sex determination and virulence are closely linked.

Collaborators on the study include James Fraser, Stephanie Diezmann, Ryan Subaran, Andria Allen, Klaus Lengeler and Fred Dietrich, Ph.D., all of Duke.

Kendall Morgan | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University

nachricht Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>