Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


How the zebrafish gets its stripes


Zebrafish, a small fresh water fish, owes its name to a striking pattern of blue stripes alternating with golden stripes.

Three major pigment cell types, black cells, reflective silvery cells, and yellow cells emerge during growth in the skin of the tiny juvenile fish and arrange as a multilayered mosaic to compose the characteristic color pattern.

Zebrafish owe their name to a repetitive pattern of blue stripes and golden interstripes parallel to the body axis.

Prateek Malhawar / Max-Planck-Institut für Entwicklungsbiologie

Yellow pigment cells, right panel, provide yellow colour to the pattern and cover the skin in two distinct shapes.

Prateek Malhawar / Max-Planck-Institut für Entwicklungsbiologie

While it was known that all three cell types have to interact to form proper stripes, the embryonic origin of the pigment cells that develop the stripes of the adult fish has remained a mystery till now. Scientists of the Max Planck Institute for Developmental Biology have now discovered how these cells arise and behave to form the zebra pattern.

Beauty in the living world amazes poets, philosophers and scientists alike. Nobel prize laureate Christiane Nüsslein-Volhard, Director of the Department for Genetics at the Max Planck Institute for Developmental Biology, has long been fascinated by the biology behind the colour patterns displayed by animals. Her group uses zebrafish as a model organism to study the genetic basis of animal development.

New research by Nüsslein-Volhard’s laboratory published in Science shows that the yellow cells undergo dramatic changes in cell shape to tint the stripe pattern of zebrafish. “We were surprised to observe such cell behaviours, as these were totally unexpected from what we knew about colour pattern formation”, says Prateek Mahalwar, first author of the study.

The study builds on a previous work from the laboratory, which was published in June this year in Nature Cell Biology (NCB), tracing the cell behaviour of silvery and black cells. Both studies describe diligent experiments to uncover the cellular events during stripe pattern formation. Individual juvenile fish carrying fluorescently labelled pigment cell precursors were imaged every day for up to three weeks to chart out the cellular behaviours.

This enabled the scientists to trace the multiplication, migration and spreading of individual cells and their progeny over the entire patterning process of stripe formation in the living and growing animal. "We had to develop a very gentle procedure to be able to observe individual fish repeatedly over long periods of time. So we used a state of the art microscope which allowed us to reduce the adverse effects of fluorescence illumination to a minimum," says Ajeet Singh, first author of the earlier NCB study.

Surprisingly, the analysis revealed that the three cell types reach the skin by completely different routes: A pluripotent cell population situated at the dorsal side of the embryo gives rise to larval yellow cells, which cover the skin of the embryo. These cells begin to multiply at the onset of metamorphosis when the fish is about two to three weeks old.

However, the black and silvery cells come from a small set of stem cells associated with nerve nodes located close to the spinal cord in each segment. The black cells reach the skin migrating along the segmental nerves to appear in the stripe region, whereas the silvery cells pass through the longitudinal cleft that separates the musculature and then multiply and spread in the skin.

Brigitte Walderich, a co-author of the Science paper, who performed cell transplantations to trace the origin of yellow cells, explains: “My attempt was to create small clusters of fluorescently labelled cells in the embryo which could be followed during larval and juvenile stages to unravel growth and behaviour of the yellow cells. We were surprised to discover that they divide and multiply as differentiated cells to cover the skin of the fish before the silvery and black cells arrive to form the stripes.”

A striking observation is that both the silvery and yellow cells are able to switch cell shape and colour, depending on their location. The yellow cells compact to closely cover the dense silvery cells forming the light stripe, colouring it golden, and acquire a loose stellate shape over the black cells of the stripes. The silvery cells thinly spread over the stripe region, giving it a blue tint.

They switch shape again at a distance into the dense form to aggregate, forming a new light stripe. These cell behaviours create a series of alternating light and dark stripes. The precise superposition of the dense form of silvery and yellow cells in the light stripe, and the loose silvery and yellow cells superimposed over the black cells in the stripe cause the striking contrast between the golden and blue coloration of the pattern.

The authors speculate that variations on these cell behaviours could be at play in generating the great diversity of colour patterns in fish. “These findings inform our way of thinking about colour pattern formation in other fish, but also in animals which are not accessible to direct observation during development such as peacocks, tigers and zebras”, says Nüsslein-Volhard.

Weitere Informationen:

Nadja Winter | Max-Planck-Institut
Further information:

Further reports about: Biology Max-Planck-Institut behaviour dense develop individual juvenile skin small spread stripe zebrafish

More articles from Life Sciences:

nachricht New study reveals what's behind a tarantula's blue hue
01.12.2015 | University of California - San Diego

nachricht Tracing a path toward neuronal cell death
01.12.2015 | Brigham and Women's Hospital

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How do Landslides control the weathering of rocks?

Chemical weathering in mountains depends on the process of erosion.

Chemical weathering of rocks over geological time scales is an important control on the stability of the climate. This weathering is, in turn, highly dependent...

Im Focus: How Cells in the Developing Ear ‘Practice’ Hearing

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular chain of events that enables the cells to make “sounds” on their own, essentially “practicing” their ability to process sounds in the world around them.

The researchers, who describe their experiments in the Dec. 3 edition of the journal Cell, show how hair cells in the inner ear can be activated in the absence...

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

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...

Im Focus: Lactate for Brain Energy

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...

All Focus news of the innovation-report >>>



Event News

European Geosciences Union meeting: Media registration now open (EGU 2016 media advisory 1)

01.12.2015 | Event News

Urbanisation and migration from rural areas challenging agriculture in Eastern Europe

30.11.2015 | Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Latest News

USGS projects large loss of Alaska permafrost by 2100

01.12.2015 | Earth Sciences

New study reveals what's behind a tarantula's blue hue

01.12.2015 | Life Sciences

Climate Can Grind Mountains Faster Than They Can Be Rebuilt

01.12.2015 | Earth Sciences

More VideoLinks >>>