Nav: Home

Flatworms left in sunlight spur investigations into rare metabolic disorders

May 31, 2016

A type of flatworm could be a new weapon in the hunt for better ways to treat a group of diseases that can cause extreme sensitivity to light, facial hair growth, and hallucinations, according to a study published in the journal eLife.

Porphyrias are a group of rare metabolic disorders characterized by red and purple pigments accumulating in the body. With the accidental discovery that the skin color of the flatworm Schmidtea mediterranea (S. mediterranea) changes under prolonged exposure to sunlight, these animals could provide a new model for studying the diseases.

Faculty and student researchers from Keene State College, New Hampshire, show that the flatworm generates light-activated molecules called porphyrins in its skin pigment cells using the same biochemical pathway as that involved in human porphyrias.

Their research developed from the unexpected observation by undergraduate students that the flatworms they were investigating changed color from brown to white when exposed to sunlight for several days. It could now lead to future drug development to meet patient demands for more effective treatments.

"Porphyrias are typically caused by inherited mutations that involve a buildup of porphyrins in various parts of the body. Although naturally created during the generation of heme, a substance required for oxygen transport in red blood cells, porphyrins can have toxic effects when their levels increase," says Jason Pellettieri, corresponding author and Associate Professor of Biology at Keene State College.

"For example, porphyrins deposited in the skin cause swelling, blistering, and lesions upon exposure to bright light. Neurological issues can also arise, ranging from anxiety and confusion to seizures or paralysis. These episodes, which can last for weeks, can be triggered by drugs, hormonal changes, and dieting or fasting."

The porphyrins in S. mediterranea give rise to their normal skin pigmentation. When the animals are exposed to intense light for extended periods of time (a situation unlikely to occur in the wild), porphyrin production leads to pigment cell loss, changing the animals' skin color to white.

To investigate this photosensitivity, the researchers first tested infrared and ultraviolet lights on the flatworms, which had no effect on their skin. In contrast, intense visible light altered their coloring, with just over half of them developing one or more small tissue lesions.

"Our findings show that prolonged light exposure eliminates the flatworms' pigment cells through a mechanism involving porphyrin-dependent photosensitization. The animals then repigment when they are no longer exposed to light," explains lead author Bradford Stubenhaus.

During the course of the research, the team also noticed a positive relationship between how long the flatworms were fasted before light exposure and the extent of their photosensitivity.

To document this relationship, they starved the animals for one, seven, 14 or 30 days before exposing them to light. Depigmentation was strongly accelerated with starvation, and then reversed with a single feeding 24 hours before light exposure.

These discoveries suggest that S. mediterranea could help identify new treatments for easing porphyrin-mediated photosensitivity or separating the relationship between dieting or fasting and the onset of disease symptoms.

"Although porphyrias are usually manageable diseases, reliance on the mainstay treatment, namely intravenous heme, or liver transplantation, for more severe cases can result in significant complications. There are also no approved preventative therapies for patients who suffer recurrent attacks," says Pellettieri.

"Our studies show that flatworms such as S. mediterranea could potentially change this. They have recently emerged as a useful model for human disorders, including Usher syndrome - a genetic disorder that affects vision, hearing, and sometimes balance - and cystic kidney disease. We can now add porphyria to this growing list, with plans to use the animals to screen for novel therapies in the near future."
-end-
Reference

The paper 'Light-induced depigmentation in planarians models the pathophysiology of acute porphyrias' can be freely accessed online at eLife.14175">http://dx.doi.org/10.7554/eLife.14175. Contents, including text, figures, and data, are free to reuse under a CC BY 4.0 license.

Media contacts

Emily Packer, eLife
e.packer@elifesciences.org
01223 855373

Kelly Ricaurte, Keene State College
kricaurte@keene.edu
603-358-2119

About eLife

eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.

About Keene State College

Keene State College is a preeminent public liberal arts college that ensures student access to world-class academic programs. Integrating academics with real-world application and active community and civic engagement, Keene State College prepares graduates to meet society's challenges by thinking critically, acting creatively, and serving the greater good. To learn more about Keene State College, visit http://www.keene.edu.

eLife

Related Biology Articles:

Cell biology: Compartments and complexity
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists have taken a closer look at the subcellular distribution of proteins and metabolic intermediates in a model plant.
Cell biology: The complexity of division by two
Ludwig-Maximilians-Universitaet (LMU) in Munich researchers have identified a novel protein that plays a crucial role in the formation of the mitotic spindle, which is essential for correct segregation of a full set of chromosomes to each daughter cell during cell division.
Cell biology: Dynamics of microtubules
Filamentous polymers called microtubules play vital roles in chromosome segregation and molecular transport.
The biology of color
Scientists are on a threshold of a new era of color science with regard to animals, according to a comprehensive review of the field by a multidisciplinary team of researchers led by professor Tim Caro at UC Davis.
Kinky biology
How and why proteins fold is a problem that has implications for protein design and therapeutics.
More Biology News and Biology Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...