Neurobiologists from the University of Zurich have discovered that this camouflage mechanism actually started out as sunscreen to protect the fish against DNA damaging shortwave solar radiation at embryonic stages.
Zebrafish with different pigmentation and camouflage. The bottom animal is on a light subsurface. The top animal is blind, thus incapable of discerning the lightness of the subsurface and
Picture: Stephan Neuhauss / UZH
Camouflage among zebrafish larvae. The left-hand larva is exposed to bright light and has little pigmentation; the right-hand larva against a dark subsurface is more heavily pigmented.
Picture: Stephan Neuhauss / UZH
For diurnal animals like zebrafish embryos, which grow up in shallow pools and are practically see-through, exposure to the sun constitutes a major problem since ultraviolet (UV) radiation damages DNA.
Neurobiologists Stephan Neuhauss and Kaspar Müller from the Institute of Molecular Biology at the University of Zurich set about investigating which mechanisms zebrafish embryos use to protect themselves against the aggressive UV radiation. Interestingly, the two scientists reveal in their article recently published in the journal PLOS ONE, the UV-protection mechanism also doubles as camouflage.
Sunscreen already from day two
For their study, the scientists examined zebrafish embryos, the skin cells of which already possess pigments known as melanosomes from the second day after fertilization – even before their eyes have developed. “In strong solar radiation, the pigments spread along predetermined paths within the cells, after which the zebrafish embryo appears darker,” explains Neuhauss. As the researchers discovered, this distribution process of dark pigments in the presence of intense light always takes place, regardless of whether the embryo is on a light or dark subsurface. Surprisingly, the embryos display a noticeable change from the third day after fertilization: They adapt to the subsurface. According to Neuhauss, this is because the embryos can see from day three and have eyes with UV-sensitive photoreceptors in the retina. From this moment on, they are able to discern whether they are on a light or dark subsurface and can adapt and thus camouflage themselves accordingly. As long as the animal is in the embryonic stage and see-through, however, the benefits of UV protection prevail.When the skin is no longer transparent and does not require protection against aggressive radiation, the selective distribution of the pigments within the skin cells is predominantly used for camouflage purposes. And with good reason: Being able to adapt to a lighter or darker subsurface and camouflage yourself reduces the chance of being spotted and eaten. “The original UV protection turns into a camouflage mechanism – a striking example of the secondary use of an existing capability,” Neuhauss concludes.
Kaspar P. Müller, Stephan C. F. Neuhauss, Sunscreen for Fish: Co-option of UV light protection for camouflage. PLOS ONE. January 29, 2014. Link: http://dx.plos.org/10.1371/journal.pone.0087372
Bettina Jakob | Universität Zürich
Understanding a missing link in how antidepressants work
25.11.2015 | Max Planck Institute of Psychiatry, München
Plant Defense as a Biotech Tool
25.11.2015 | Austrian Centre of Industrial Biotechnology (ACIB)
The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...
AWI researchers’ unique 15-year observation series reveals how sensitive marine ecosystems in polar regions are to change
The warming of arctic waters in the wake of climate change is likely to produce radical changes in the marine habitats of the High North. This is indicated by...
25.11.2015 | Event News
17.11.2015 | Event News
21.10.2015 | Event News
25.11.2015 | Agricultural and Forestry Science
25.11.2015 | Earth Sciences
25.11.2015 | Physics and Astronomy