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:12/2/2016)... Dec. 1, 2016   SoftServe , a ... BioLock , an electrocardiogram (ECG) biosensor analysis system ... key IoT asset. The smart system ensures device-to-device ... steering wheel and mobile devices to easily ,recognize, ... As vehicle technology advances, so too must ...
(Date:11/29/2016)... , Nov. 29, 2016 BioDirection, a ... point-of-care products for the objective detection of concussion and ... company has successfully completed a meeting with the U.S. ... Tbit™ blood test Pre-Submission Package. During the meeting company ... system as a precursor to commencement of a planned ...
(Date:11/28/2016)... "The biometric system market ... The biometric system market is in the growth stage ... future. The biometric system market is expected to be ... CAGR of 16.79% between 2016 and 2022. Government initiative ... in smartphones, rising use of biometric technology in financial ...
Breaking Biology News(10 mins):
(Date:11/30/2016)... York , November 30, 2016 ... as a few players hold a dominant share in ... Charles River Laboratories International, Inc., and Merck KGaA, held ... in 2015. Transparency Market Research observes that these companies ... focused on development products that are do not require ...
(Date:11/30/2016)... Fla. , Nov. 30, 2016 Biotest ... products, is pleased to announce the addition of its ... Kearney, Nebraska . The 15,200 square ... on November 29th, 2016 and brings the total number ... Ileana Carlisle , BPC,s Chief Executive Officer ...
(Date:11/30/2016)... /PRNewswire/ -  Equicare Health Inc ., the leading supplier ... one of the top 100 companies in the 2016 ... distinguishes the top digital health companies across the globe. ... this year continually upgrading our product with the ongoing ... team," says Len Grenier , CEO of Equicare ...
(Date:11/30/2016)... BEIJING , Nov. 30, 2016 /PRNewswire/ ... of genomic services and solutions with cutting edge next-generation ... has completed a USD $75 Million [515 Million RMB] ... CMB International Capital Management ( Shenzhen ) ... Ltd. ("SDIC Innovation") and Shanghai Sigma Square Investment Center ...
Breaking Biology Technology: