Skip to main content
NIH Intramural Research Program, Our Research Changes Lives

Navigation controls

  • Search
  • Menu

Social follow links

  • Podcast
  • Instagram
  • Twitter
  • YouTube
  • LinkedIn

Main navigation

  • About Us
    • What Is the IRP?
    • History
    • Honors
      • Nobel Prize
      • Lasker Award
      • Breakthrough Prize
      • Presidential Early Career Award for Scientists and Engineers (PECASE)
      • Presidential Medal of Freedom
      • National Medal of Science
      • Searle Scholars
      • The National Academy of Sciences
      • The National Academy of Medicine
      • The National Academy of Engineering
      • The American Academy of Arts and Sciences
      • National Medal of Technology & Innovation
      • Samuel J. Heyman Service to America Medals
      • Crafoord Prize
      • Fellows of the Royal Society
      • Canada Gairdner Awards
    • Organization & Leadership
    • Our Programs
      • NCI
      • NEI
      • NHGRI
      • NHLBI
      • NIA
      • NIAAA
      • NIAID
      • NIAMS
      • NIBIB
      • NICHD
      • NIDA
      • NIDCD
      • NIDCR
      • NIDDK
      • NIEHS
      • NIMH
      • NIMHD
      • NINDS
      • NINR
      • NLM
      • CC
      • NCATS
      • NCCIH
    • Research Campus Locations
    • Contact Information
  • Our Research
    • Scientific Focus Areas
      • Biomedical Engineering & Biophysics
      • Cancer Biology
      • Cell Biology
      • Chemical Biology
      • Chromosome Biology
      • Clinical Research
      • Computational Biology
      • Developmental Biology
      • Epidemiology
      • Genetics & Genomics
      • Health Disparities
      • Immunology
      • Microbiology & Infectious Diseases
      • Molecular Biology & Biochemistry
      • Molecular Pharmacology
      • Neuroscience
      • RNA Biology
      • Social & Behavioral Sciences
      • Stem Cell Biology
      • Structural Biology
      • Systems Biology
      • Virology
    • Principal Investigators
      • View by Investigator Name
      • View by Scientific Focus Area
    • Accomplishments
      • View All Accomplishments by Date
      • View All Health Topics
      • The Body
      • Health & Wellness
      • Conditions & Diseases
      • Procedures
    • Accelerating Science
      • Investing in Cutting-Edge Animal Models
      • Creating Cell-Based Therapies
      • Advancing Computational and Structural Biology
      • Combating Drug Resistance
      • Developing Novel Imaging Techniques
      • Charting the Pathways of Inflammation
      • Zooming in on the Microbiome
      • Uncovering New Opportunities for Natural Products
      • Stimulating Neuroscience Research
      • Pursuing Precision Medicine
      • Unlocking the Potential of RNA Biology and Therapeutics
      • Producing Novel Vaccines
    • Research in Action
      • View All Stories
      • Too Much of a Good Thing
      • Turning Face Perception on Its Head
      • Safeguarding a Second Chance at Life
      • A Biological Betrayal
    • Trans-IRP Research Resources
      • Supercomputing
    • IRP Review Process
    • Commercializing Inventions
  • NIH Clinical Center
    • Clinical Center Facilities
    • Advancing Translational Science
    • Clinical Trials
      • Get Involved with Clinical Research
      • Physician Resources
  • News & Events
    • In the News
    • I am Intramural Blog
    • Speaking of Science Podcast
    • SciBites Video Shorts
    • The NIH Catalyst Newsletter
    • Events
  • Careers
    • Faculty-Level Scientific Careers
    • Trans-NIH Scientific Recruitments
      • Stadtman Tenure-Track Investigators
        • Science, the Stadtman Way
        • Earl Stadtman Investigator Frequently Asked Questions
      • Lasker Clinical Research Scholars
      • Independent Research Scholar
    • Scientific & Clinical Careers
    • Administrative Careers
  • Research Training
    • Program Information
    • Training Opportunities
    • NIH Work/Life Resources
The NIH Catalyst: A Publication About NIH Intramural Research

National Institutes of Health • Office of the Director | Volume 21 Issue 1 • January–February 2013

Let There Be Light

Sea Creatures Providing Clues on the Evolution of Vision

by JEANNINE MJOSETH, NHGRI

Bioluminescent sea creatures that emit and detect light are providing clues to the evolution of sight and may, in time, shed light on our understanding of eye diseases. Research published in a recent issue of BMC Biology has pinpointed the genes involved in making and sensing light in this organism.

Comb jellies, also known as ctenophores, evolved more than 500 million years ago. They’re among the earliest metazoans, a group that comprises all multicellular animals. At a maximum length of five inches, they have the distinction of being the largest animals to use cilia for locomotion. Ctenophores are found in all oceans of the world and have recently invaded the Black, Caspian and Baltic Seas, where they are considered pests because they consume fish larvae. The subject of this study was a comb jelly called Mnemiopsis leidyi that lives off the Eastern seaboard from Maine to Florida.

jelly fish

William Browne, University of Miami

Comb jellies, like this Mnemiopsis leidyi, may have evolved more than 500 million years ago, but today they are providing clues to NHGRI scientists as to how sight developed in other creatures, including humans.

The study was performed by Andy Baxevanis and his group in the Genome Technology Branch of NHGRI. They based their findings on the whole genome of Mnemiopsis leidyi, which the group recently sequenced, assembled and annotated. Baxevanis and his team will soon publish a study analyzing the organism’s genome, the first bioluminescent animal and the first ctenophore species for which there is a whole genome sequence.

“Comb jellies are quite beautiful,” said Christine E. Schnitzler, the paper’s first author and a postdoctoral fellow in Baxevanis’s group. “When light reflects off their cilia, it creates a rainbow of colors. But that’s not the same as bioluminescence, which you can only see in the dark.”

Comb jellies’ ability to generate light comes from genes that produce photoproteins. Two types of chemicals involved in light production, called luciferin and luciferase, are bound together in a photoprotein. This molecule can be triggered to produce light when calcium is added to the system. Photoproteins emit flashes of very bright light for a fraction of a second.

While the researchers expected to find photoproteins in comb jellies, they didn’t expect to find 10 different photoproteins that were clustered into two groups in the genome. The researchers think that having multiple photoprotein genes allows the animal to produce larger amounts of photoprotein and emit more light quickly.

“These protoproteins were tandemly arrayed,” Schnitzler said. “This is fascinating for an evolutionary biologist because it means that these photoproteins somehow evolved as a group.”

The scientists found that light-emitting photoproteins were located in the same cells as opsin genes, the most primitive type of light detector in animals. All animals use opsins to catch photons of light, and finding a functional opsin in a ctenophore indicates that they have been preserved throughout animal evolution.

The co-localization of the opsin genes and the photoproteins may confer an advantage to the animal: it might be a feedback mechanism that allows the comb jelly to maintain the right amount of bioluminescence or it may enhance reproductive or defensive capabilities, Schnitzler suggested.

Opsins are also located near the apical sensory organ, opposite the mouth. An apical sensory organ contains large sensory cilia that help it maintain proper vertical orientation or change swimming direction.
Baxevanis sees a broader context for using comparative genomic approaches focused on the early animals such as comb jellies. “To get a handle on the evolution of vision, we first need to understand the evolution of protein families like the photoproteins and the opsins,” he said.

“These organisms may also help us figure out at what point in time a particular disease-associated gene emerged.”


NHGRI authors: C.E. Schnitzler, M. Park, J. Gupta, S.Y. Brooks, R.W. Blakesley, and A.D. Baxevanis; BMC Biol 10:107, 2012

This page was last updated on Friday, April 29, 2022

  • Issue Overview
  • Features
    • The Stadtman Legacy
    • NIH-Lasker Scholars
    • Let There Be Light
    • Obituaries 2012
    • Helping Native Americans
    • An Eye for an Ear
  • Departments
    • From the Deputy Director for Intramural Research
    • Research Briefs
    • Announcements
    • Alumni News
    • Colleagues: Recently Tenured
    • Photographic Moment
    • The Training Page
    • The SIG Beat
  • Issue Contents
  • Download this issue as a PDF

Catalyst menu

  • Current Issue
  • Previous Issues
  • About The NIH Catalyst
  • Contact The NIH Catalyst
  • Share Your Story
  • NIH Abbreviations

Catalyst links

  • Follow The NIH Catalyst

Subscribe Today!

Subscribe to The NIH Catalyst Newsletter and receive email updates.

Subscribe

Get IRP Updates

Subscribe

  • Email
  • Print
  • Share Twitter Facebook LinkedIn

Main navigation

  • About Us
    • What Is the IRP?
    • History
    • Honors
    • Organization & Leadership
    • Our Programs
    • Research Campus Locations
    • Contact Information
  • Our Research
    • Scientific Focus Areas
    • Principal Investigators
    • Accomplishments
    • Accelerating Science
    • Research in Action
    • Trans-IRP Research Resources
    • IRP Review Process
    • Commercializing Inventions
  • NIH Clinical Center
    • Clinical Center Facilities
    • Advancing Translational Science
    • Clinical Trials
  • News & Events
    • In the News
    • I am Intramural Blog
    • Speaking of Science Podcast
    • SciBites Video Shorts
    • The NIH Catalyst Newsletter
    • Events
  • Careers
    • Faculty-Level Scientific Careers
    • Trans-NIH Scientific Recruitments
    • Scientific & Clinical Careers
    • Administrative Careers
  • Research Training
    • Program Information
    • Training Opportunities
    • NIH Work/Life Resources
  • Department of Health and Human Services
  • National Institutes of Health
  • USA.gov

Footer

  • Home
  • Contact Us
  • IRP Brand Materials
  • HHS Vulnerability Disclosure
  • Web Policies & Notices
  • Site Map
  • Search