Featured Research

from universities, journals, and other organizations

Insight Into Our Sight: A New View On The Evolution Of The Eye Lens

Date:
September 27, 2005
Source:
Cell Press
Summary:
The evolution of complex and physiologically remarkable structures such as the vertebrate eye has long been a focus of intrigue and theorizing by biologists. In work reported this week in Current Biology, the evolutionary history of a critical eye protein has revealed a previously unrecognized relationship between certain components of vertebrate eyes and those of the more primitive light-sensing systems of invertebrates. The findings help clarify our conceptual framework for understanding how the vertebrate eye, as we know it, has emerged over evolutionary time.

The evolution of complex and physiologically remarkable structures suchas the vertebrate eye has long been a focus of intrigue and theorizingby biologists. In work reported this week in Current Biology, theevolutionary history of a critical eye protein has revealed apreviously unrecognized relationship between certain components ofvertebrate eyes and those of the more primitive light-sensing systemsof invertebrates. The findings help clarify our conceptual frameworkfor understanding how the vertebrate eye, as we know it, has emergedover evolutionary time.

Related Articles


The work is reported by Sebastian Shimeld at the University ofOxford and colleagues at the University of London and RadboudUniversity in The Netherlands.

Our sight relies on the ability of our eye to form a clear,focused image on the retina. The critical component in focusing is theeye lens, and the physical properties that underlie the transparency ofthe lens, as well as its ability to precisely refract light, arise fromthe high concentrations of special proteins called crystallins found inlens cells.

Fish, frogs, birds and mammals all experience image-formingvision, thanks to the fact that their eyes all express crystallins andform a lens; however, the vertebrates' nearest invertebrate relatives,such as sea squirts, have only simple eyes that detect light but areincapable of forming an image. This has lead to the view that the lensevolved within the vertebrates early in vertebrate evolution, and itraises a long-standing question in evolutionary biology: How could acomplex organ with such special physical properties have evolved?

In their new work, Shimeld and colleagues approached thisquestion by examining the evolutionary origin of one crystallin proteinfamily, known as the �?-crystallins. Focusing on sea squirts,invertebrate cousins of the vertebrate lineage, the researchers foundthat these creatures possess a single crystallin gene, which isexpressed in its primitive light-sensing system. The identification ofthe sea squirt's crystallin strongly suggests that it is the singlegene from which the vertebrate �?-crystallins evolved.

The researchers also found that, remarkably, expression of thesea squirt crystallin gene is controlled by genetic elements that alsorespond to the factors that control lens development in vertebrates:The researchers showed that when regulatory regions of the sea squirtgene are transferred to frog embryos, these regulatory elements drivegene expression in the tadpoles' own visual system, including the lens.This strongly suggests that prior to the evolution of the lens, therewas a regulatory link between two tiers of genes: those that wouldlater become responsible for controlling lens development, and thosethat would help give the lens its special physical properties. Thiscombination of genes appears to have then been co-opted in an earlyvertebrate during the evolution of its visual system, giving rise tothe lens.

###

The researchers include Sebastian M. Shimeld, University of Oxford,Oxford, United Kingdom; Andrew G. Purkiss, Orval A. Bateman, andChristine Slingsby of Birkbeck College University of London, UnitedKingdom; Ron P.H. Dirks and Nicolette H. Lubsen of Radboud University,Nijmegen, The Netherlands. This work was supported by the MedicalResearch Council, UK and the Biotechnology and Biological SciencesResearch Council.

Shimeld et al.: "Urochordate gamma-crystallin and theevolutionary origin of the vertebrate eye lens." Publishing in CurrentBiology, Vol. 15, pages 1684-1689, September 20, 2005. DOI10.1016/j.cub.2005.08.046 www.current-biology.com


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Insight Into Our Sight: A New View On The Evolution Of The Eye Lens." ScienceDaily. ScienceDaily, 27 September 2005. <www.sciencedaily.com/releases/2005/09/050926074038.htm>.
Cell Press. (2005, September 27). Insight Into Our Sight: A New View On The Evolution Of The Eye Lens. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2005/09/050926074038.htm
Cell Press. "Insight Into Our Sight: A New View On The Evolution Of The Eye Lens." ScienceDaily. www.sciencedaily.com/releases/2005/09/050926074038.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins