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 Closing the carbon loop
08.12.2016 | University of Pittsburgh

nachricht Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>