Hungry eyes: Spiders lose vision when they're starving
Findings could improve understanding of how nutrition affects macular degeneration

Date:
April 20, 2023
Source:
University of Cincinnati
Summary:
Biologists have discovered that underfed jumping spiders lose light-
sensitive cells that are key to their vision.


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FULL STORY ========================================================================== Biologists at the University of Cincinnati discovered that underfed
jumping spiders lose light-sensitive cells that are key to their vision.


==========================================================================
UC College of Arts and Sciences Professor Elke Buschbeck and her
co-authors studied photoreceptors in the eyes of bold jumping spiders,
tiny eight-legged predators found across North America. The little
hunters rely on their keen vision to stalk prey.

But researchers found that underfed spiders begin to lose photoreceptors
that give them such good eyesight. Their findings could improve our understanding of the role that nutrition plays in common age-related
vision problems such as macular degeneration.

The study was published in the journal Vision Research.

Their discovery occurred by serendipity while examining the eyes
of wild-caught bold jumping spiders using her lab's custom-made
ophthalmoscope, which can take photos of the retinas of insects and
spiders. They found dark spots on some of the spiders' photoreceptors, suggesting they had degenerated during its life or development.

"You could tell just by looking at them that some of the photoreceptors
had died," Buschbeck said.

"But are the photoreceptors really degenerating?" UC doctoral student
Shubham Rathore asked. "Or are they just getting bleached by the way we
do the experiment?" Rathore turned to electron microscopy to confirm
that the cells indeed were dying.

The study suggests jumping spiders are a compelling model to study
retinal and neuronal health.

Did poor nutrition cause it? To test their hypothesis, Miranda Brafford
and John Gote', both UC graduates, studied two groups of captive spiders,
one fed a normal unrestricted diet and another that was given half
portions. In the underfed group, spiders lost more photoreceptors,
particularly in the part of the retina that has the highest density
of them.

"It's the functional equivalent of the macula in our eyes," Buschbeck
said.

That is the part of the eye that processes visual information directly
in front of you.

"Photoreceptors are energetically costly. It's hard to keep up with
their energy needs," Buschbeck said. "If you deprive them of nutrition,
the system fails." Macular degeneration affects an estimated 20 million
people in the United States. It's the most common cause of age-related
vision loss and has no cure.

"What's interesting is macular degeneration in humans also has evidence
of being linked to metabolic processes and difficulty with energy being delivered," Buschbeck said.

Rathore and Buschbeck said they would like to see if the degeneration
begins in the support tissues around the photoreceptors and what nutrients
in particular support good visual health.

Study senior author Annette Stowasser, an assistant professor in
UC's College of Arts and Sciences, said it's premature to draw direct comparisons between vision deficits in spiders and people.

"To be able to say anything about how this may inform treatments in
people, first carefully designed studies would need to tease out which
exact nutrients are involved, which may depend on environmental conditions
and other factors," Stowasser said.

"However, that nutrient deprivation can have the shown effect indicates
the importance of paying close attention to the effects of nutrients,"
she said.

Co-author Nathan Morehouse is director of UC's Institute for Research
in Sensing and has studied the vision of jumping spiders around the world.

"Wouldn't it be wild if a breakthrough in macular degeneration treatments
for humans was inspired by work on jumping spiders common to back yards
across the United States?" said Morehouse, an associate professor in
biological sciences.

"Sometimes answers to challenging problems can come from unexpected
places," he said.

The study was supported by grants from the National Science Foundation.

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========================================================================== Story Source: Materials provided by University_of_Cincinnati. Original
written by Michael Miller. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. Shubham Rathore, John T. Gote', Miranda Brafford, Nathan
I. Morehouse,
Elke K. Buschbeck, Annette Stowasser. Nutrition-induced
macular- degeneration-like photoreceptor damage in jumping
spider eyes. Vision Research, 2023; 206: 108185 DOI:
10.1016/j.visres.2023.108185 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230420135311.htm

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