Navigation Links
Uncovering secrets of life in the ocean
Date:11/19/2008

Larvae of marine invertebrates worms, sponges, jellyfish - have the simplest eyes that exist. They consist of no more than two cells: a photoreceptor cell and a pigment cell. These minimal eyes, called eyespots, resemble the 'proto-eyes' suggested by Charles Darwin as the first eyes to appear in animal evolution. They cannot form images but allow the animal to sense the direction of light. This ability is crucial for phototaxis the swimming towards light exhibited by many zooplankton larvae. Myriads of planktonic animals travel guided by light every day. Their movements drive the biggest transport of biomass on earth.

"For a long time nobody knew how the animals do phototaxis with their simple eyes and nervous system," explains Detlev Arendt, whose team carried out the research at EMBL. "We assume that the first eyes in the animal kingdom evolved for exactly this purpose. Understanding phototaxis thus unravels the first steps of eye evolution."

Studying the larvae of the marine ragworm Platynereis dumerilii, the scientists found that a nerve connects the photoreceptor cell of the eyespot and the cells that bring about the swimming motion of the larvae. The photoreceptor detects light and converts it into an electrical signal that travels down its neural projection, which makes a connection with a band of cells endowed with cilia. These cilia - thin, hair-like projections - beat to displace water and bring about movement.

Shining light selectively on one eyespot changes the beating of the adjacent cilia. The resulting local changes in water flow are sufficient to alter the direction of swimming, computer simulations of larval swimming show.

The second eyespot cell, the pigment cell, confers the directional sensitivity to light. It absorbs light and casts a shadow over the photoreceptor. The shape of this shadow varies according to the position of the light source and is communicated to the cilia through the signal of the photoreceptor.

"Platynereis can be considered a living fossil," says Gspr Jkely, former member of Arendt's lab who now heads a group at the MPI for Developmental Biology, "it still lives in the same environment as its ancestors millions of years ago and has preserved many ancestral features. Studying the eyespots of its larva is probably the closest we can get to figuring out what eyes looked like when they first evolved."

It is likely that the close coupling of light sensor to cilia marks an important, early landmark in the evolution of animal eyes. Many contemporary marine invertebrates still employ the strategy for phototaxis.


'/>"/>

Contact: Anna-Lynn Wegener
wegener@embl.de
49-622-138-7452
European Molecular Biology Laboratory
Source:Eurekalert  

Related biology news :

1. Landmark study unlocks stem cell, DNA secrets to speed therapies
2. The making of Dig It! the Secrets of Soil exhibit
3. Monash researchers uncover cancer survival secrets
4. Power of molecular imaging reveals secrets of the heart
5. Secrets of cooperation between trees and fungi revealed
6. Genetic tags reveal secrets of memories staying power in mice
7. Birds, bats and insects hold secrets for aerospace engineers
8. Research reveals secrets of alcohols effect on brain cells
9. New research to decode the genetic secrets of prolific potato pest
10. Ripening secrets of the vine revealed
11. Eat chocolate, drink wine, add fun to life: SLU geriatrician shares secrets of staying young
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Uncovering secrets of life in the ocean
(Date:6/2/2016)... The Department of Transport Management (DOTM) of ... Dollar project, for the , Supply and Delivery ... IT Infrastructure , to Decatur ... Identity Management Solutions. Numerous renowned international vendors participated in the ... was selected for the most compliant and innovative solution. The ...
(Date:6/1/2016)... , June 1, 2016 ... in Election Administration and Criminal Identification to Boost Global ... a recently released TechSci Research report, " Global Biometrics ... Region, Competition Forecast and Opportunities, 2011 - 2021", the ... billion by 2021, on account of growing security concerns ...
(Date:5/16/2016)...   EyeLock LLC , a market leader of ... an IoT Center of Excellence in Austin, ... of embedded iris biometric applications. EyeLock,s iris ... security with unmatched biometric accuracy, making it the most ... EyeLock,s platform uses video technology to deliver a fast ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... June 27, 2016   Ginkgo Bioworks , a ... engineering, was today awarded as one of the ... the world,s most innovative companies. Ginkgo Bioworks is ... the real world in the nutrition, health and ... directly with customers including Fortune 500 companies to ...
(Date:6/24/2016)... 24, 2016 Epic Sciences unveiled a ... susceptible to PARP inhibitors by targeting homologous recombination ... The new test has already been incorporated into ... cancer types. Over 230 clinical trials ... pathways, including PARP, ATM, ATR, DNA-PK and WEE-1. ...
(Date:6/24/2016)... Raleigh, NC (PRWEB) , ... June 24, 2016 , ... ... find the most commonly-identified miRNAs in people with peritoneal or pleural mesothelioma. Their findings ... here to read it now. , Diagnostic biomarkers are signposts in the blood, ...
(Date:6/23/2016)... ... 2016 , ... UAS LifeSciences, one of the leading manufacturers ... Probiotics, into Target stores nationwide. The company, which has been manufacturing high quality ... list of well-respected retailers. This list includes such fine stores as Whole Foods, ...
Breaking Biology Technology: