Marine biologist Fleur Van Duyl from the Royal Netherlands Institute for Sea Research is fascinated by the energy budgets that support coral reefs in this impoverished environment.
According to van Duyl's former student, Jasper De Goeij, Halisarca caerulea sponges grow in the deep dark cavities beneath reefs, and 90% of their diet is composed of dissolved organic carbon, which is inedible for most other reef residents. But when De Goeij measured the amount of carbon that the brightly coloured sponges consumed he found that they consume half of their own weight each day, yet they never grew. What were the sponges doing with the carbon?
Were the sponges really consuming that much carbon, or was there a problem with De Goeij's measurements? He had to find out where the carbon was going to back up his measurements and publishes his discovery that sponges have one of the fastest cell division rates ever measured, and instead of growing they discard the cells. Essentially, the sponges recycle carbon that would otherwise be lost to the reef. De Goeij publishes his discovery on November 13 2009 in The Journal of Experimental Biology at http://jeb.biologists.org.
Travelling to the Dutch Antilles with his student, Anna De Kluijver, De Goeij started SCUBA diving with the sponges to find out how much carbon they consume. 'It is quite dark and technically difficult to work in the cavities,' explains De Goeij, but the duo collected sponges, placed them in small chambers and exposed the sponges to 5- bromo-2Œ-deoxyuridine (BrdU). 'The BrdU is only incorporated into the DNA of dividing cells,' explains De Goeij, so cells that carry the BrdU label must be dividing, or have divided, since the molecule was added to the sponge's water, and cells can only divide if they are taking up carbon. But when De Goeij returned to the Netherlands with his samples, he had problems finding the elusive label.
Discussing the BrdU detection problem with his father, biochemist Anton De Goeij, De Goeij Senior offered to introduce his son to Bert Schutte in Maastricht, who had developed a BrdU detection system for use in cancer therapy. Maybe he could help De Goeij Junior find evidence of cell division in his sponges.
Taking his samples to Jack Cleutjens's Maastricht Pathology laboratory, De Goeij was finally able to detect the BrdU label in his sponge cells. Amazingly, half of the sponge's choanocyte (filtration) cells had divided and the choanocyte's cell division cycle was a phenomenally short 5.4 hours. 'That is quicker than most bacteria divide,' exclaims De Goeij.
The sponge was able to take up the colossal amounts of organic carbon that De Goeij had measured, but where was the carbon going: the sponges weren't growing. De Goeij tested to see if the cells were dying and being lost, but he couldn't find any evidence of cell death.
Presenting his results to the Maastricht Pathology Department, someone said 'Lets look at this like a human intestine, then you should see shedding where old cells detach from the epithelia'. De Goeij knew that he had seen some loose cells, and thought that they were artefacts from cutting the samples, but when he and his Pathology Department colleagues went back and looked at the samples, De Goeij realised that choanocytes were shedding all over the place. And then De Goeij remembered the tiny piles of brown material he found next to the sponges in the aquarium every morning.
The sponges were shedding the newly divided cells, which other reef residents could now consume. 'Halisarca caerulea is the great recycler of energy for the reef by turning over energy that nobody else can use [dissolved organic carbon] into energy that everyone can use [discarded choanocytes],' explains De Goeij.
IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org
REFERENCE: De Goeij, J. M., De Kluijver, A., Van Duyl, F. C., Vacelet, J., Wijffels, R. H., De Goeij, A. F. P. M., Cleutjens, J. P. M. and Schutte, B. (2009). Cell kinetics of the marine sponge Halisarca caerulea reveal rapid cell turnover and shedding. J. Exp. Biol. 212, 3892-3900.
Full text of the article is available ON REQUEST. To obtain a copy contact Kathryn Knight, The Journal Of Experimental Biology, Cambridge, UK. Tel: +44 (0)1223 425525 or email firstname.lastname@example.org
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT email@example.com
Kathryn Knight | EurekAlert!
Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society
127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences