Brewing yeasts reveal secrets of chromosomal warfare and dysfunction

Study may lead to new understanding of how new species form

2014-06-25

(Press-News.org) SEATTLE –Using two yeasts that have been used to brew tea and beer for centuries, researchers at Fred Hutchinson Cancer Research Center have revealed how reproductive barriers might rapidly arise to create species boundaries. Schizosaccharomyces pombe has been used to brew beer in Africa, whereas its close relative S. kombucha is a component of kombucha tea commonly found in health-food stores.

A team of researchers led by Dr. Sarah Zanders of the Basic Sciences Division at Fred Hutch, has uncovered why hybrids between these yeasts (commonly referred to as fission yeasts) are almost completely sterile despite being 99.5 percent identical at the DNA level.

The study, published this month in the open-access journal eLife, found that the surprisingly rapid onset of infertility has two major causes. First, the study revealed that genome rearrangements limit the ability of the hybrids to produce offspring that contain a full set of genes. Second, the study found that three meiotic drive genes severely decrease fertility in the hybrids. Meiotic drive genes are "selfish genes"' that persist and spread in populations by cheating the process of sexual reproduction to increase their own transmission. Zanders and colleagues found evidence of three independently acting meiotic drivers, which appear to somehow kill cells that do not inherit them. Their combined action is sufficient to almost completely debilitate hybrid fertility.

"Both changes in genome structure and meiotic drivers are commonly observed in other organisms, including in human populations," Zanders said, "but our ability to discover and fully understand their biology is greatly improved in genetic model organisms like fission yeast."

The researchers also found that the two species and hybrids between them greatly differ in their propensity to experience aneuploidy, or aberrant chromosomal configurations. Such aneuploidy is commonly observed in human cancers and is also the underlying cause of birth defects such as Down syndrome. "The model we have developed provides an exciting means to uncover the causes underlying genetic predisposition to aneuploidy," Zanders said.

The work also exemplifies the uniquely collaborative scientific atmosphere at Fred Hutch. Zanders was co-advised by Dr. Gerald Smith, whose lab at Fred Hutch studies recombination and meiosis in fission yeast, and Dr. Harmit Malik, also of the Basic Sciences Division at Fred Hutch, whose lab studies evolutionary genetic conflicts and speciation. Although this atmosphere provided the best opportunity to make new discoveries, Malik and Smith also credited Zanders' ability to bridge the strengths of both labs for the ultimate success of the project.

"Despite speciation being one of the most intriguing problems in biology, one that even Darwin termed the "mystery of mysteries", our ability to understand how new species form will be greatly enhanced by new model systems in which we can fully understand the genetic and molecular basis underlying hybrid dysfunction," Malik said. "The prospect of using these discoveries to understand the genetic basis of chromosome dysfunction and human disease is exciting, and it's a foreseeable outcome of such basic research."

INFORMATION: Grants from the American Cancer Society, National Institutes of Health, the Mathers Foundation and the Howard Hughes Medical Institute funded the research.

At Fred Hutchinson Cancer Research Center, home to three Nobel laureates, interdisciplinary teams of world-renowned scientists seek new and innovative ways to prevent, diagnose and treat cancer, HIV/AIDS and other life-threatening diseases. Fred Hutch's pioneering work in bone marrow transplantation led to the development of immunotherapy, which harnesses the power of the immune system to treat cancer with minimal side effects. An independent, nonprofit research institute based in Seattle, Fred Hutch houses the nation's first and largest cancer prevention research program, as well as the clinical coordinating center of the Women's Health Initiative and the international headquarters of the HIV Vaccine Trials Network. Private contributions are essential for enabling Fred Hutch scientists to explore novel research opportunities that lead to important medical breakthroughs. For more information visit http://www.fredhutch.org.

Contact Michael Nank
206-667-2210
media@fredhutch.org

ELSE PRESS RELEASES FROM THIS DATE:

3-D computer model may help refine target for deep brain stimulation therapy for dystonia

2014-06-25

LOS ANGELES (June 24, 2014) – Although deep brain stimulation can be an effective therapy for dystonia – a potentially crippling movement disorder – the treatment isn't always effective, or benefits may not be immediate. Precise placement of DBS electrodes is one of several factors that can affect results, but few studies have attempted to identify the "sweet spot," where electrode placement yields the best results. Researchers led by investigators at Cedars-Sinai, using a complex set of data from records and imaging scans of patients who have undergone successful DBS ...

First comprehensive pediatric concussion guidelines, available now

2014-06-25

Ottawa/Toronto, CANADA – June 25, 2014 – Pediatric emergency medicine researchers at the Children's Hospital of Eastern Ontario (CHEO) together with the Ontario Neurotrauma Foundation (ONF) today launch the first comprehensive pediatric concussion guidelines. "There have been recommendations and policies on concussion available in the past, but they tend to have focused on sports-related injury and not on children and youth," said Dr. Roger Zemek, project leader, scientist at CHEO, and Assistant Professor of Pediatrics and Emergency Medicine at the University of Ottawa. ...

Researchers treat incarceration as a disease epidemic, discover small changes help

2014-06-25

The incarceration rate has nearly quadrupled since the U.S. declared a war on drugs, researchers say. Along with that, racial disparities abound. Incarceration rates for black Americans are more than six times higher than those for white Americans, according to the U.S. Bureau of Justice Statistics. To explain these growing racial disparities, researchers at Virginia Tech are using the same modeling techniques used for infectious disease outbreaks to take on the mass incarceration problem. By treating incarceration as an infectious disease, the scientists demonstrated ...

Resolving apparent inconsistencies in optimality principles for flow processes in geosystems

2014-06-25

Optimality principles have been used, in a holistic approach, to describe flow processes in several important geosystems. Optimality principles refer to the state of a physical system that is controlled by an optimal condition subject to physical and/or resource constraints. While significant successes have been achieved in applying them, some principles appear to contradict each other. For example, scientists have found that the formation of channel networks in a river basin follows the minimization of energy expenditure (MEE) rate, while the Earth-atmosphere system ...

Net energy analysis should become a standard policy tool, Stanford scientists say

2014-06-25

Policymakers should conduct "net energy analyses" when evaluating the long-term sustainability of energy technologies, according to new Stanford University research. Net energy analysis provides a quantitative way to compare the amount of energy a technology produces over its lifetime with the energy required to build and maintain it. The technique can complement conventional energy planning, which often focuses on minimizing the financial cost of energy production, say Stanford researchers. "The clearest answer to 'why is net energy important?' is that net energy, ...

Animal testing methods for endocrine disruptors should change, team argues

2014-06-25

AMHERST, Mass. – Challenging risk assessment methods used for decades by toxicologists, a new review of the literature led by environmental health scientist Laura Vandenberg at the University of Massachusetts Amherst suggests that oral gavage, the most widely accepted method of dosing lab animals to test chemical toxicity, does not accurately mimic how humans are exposed to chemicals in everyday life. Oral gavage refers to the way researchers give chemicals to animals by putting a tube down their throats to deliver substances directly to the stomach. It has been used ...

New research shows link unlikely between insomnia symptoms and high blood pressure

2014-06-25

TORONTO, June 25, 2014–There's good news for the 30 per cent or more of adults who suffer from insomnia--difficulty falling asleep, waking up for prolonged periods during the night or unwanted early morning awakenings. New research from St. Michael's Hospital has found that insomnia does not put them at increased risk of developing high blood pressure. Dr. Nicholas Vozoris, a respirologist at St. Michael's, said there is growing concern among patients and health care providers about the potential medical consequences of insomnia, especially on the cardiovascular system. If ...

Incentives as effective as penalties for slowing Amazon deforestation

2014-06-25

The rate of deforestation in the Brazilian Amazon has declined. An international team of scientists, including one from Virginia Tech, reviewed published research about policy interventions and commodity market effects, and determined that positive incentives for farmers, counties, and states can do as much to preserve forests as public policies that call for penalties. "The challenge now is to build upon this progress," the team reports in an article in the June 6 issue of Science. "Some immediate and simple positive incentives for responsible, low-deforestation farmers ...

New research shows freshers struggle to remember basic A-level concepts

2014-06-25

University freshers struggle to remember basic concepts from their A-level studies according to new research from the University of East Anglia. A new report published today shows that even grade-A students could only remember 40 per cent of their A-Level syllabus by the first week of term at university. Researchers tested nearly 600 students in their first week of term at five universities – three of which were in the prestigious Russell Group. It is hoped that the findings will assist the re-design of A-Levels to make them more relevant to higher education. The ...

Food ingredient fears

2014-06-25

Daily headlines on internet pages and blogs claim: "New ingredient X is harmful to your health." Such warnings can scare people into avoiding these ingredients without actually knowing the facts, leading some people to have food fears about ingredients such as sugar, fat, sodium, high-fructose corn syrup (HFCS), mono sodium glutamate (MSG), and others. While some of these food fears are merited, others can be misleading. A new Cornell University study published in Food Quality and Preference, investigated who might be most prone to food fears, why, and what can they do ...

Brewing yeasts reveal secrets of chromosomal warfare and dysfunction

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: