2009/05/01 253. zenbakia

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• Biologia
• Zoologia
• Farmakologia
• Ikerketa-zentroak

Laboratory star with stripes

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(Photo: Lukas Roth)

Zebrafish is one of the animal models used in the laboratory. It is less known than mouse and lab rat, but more and more is used. It has not been incorporated into the laboratory, began to be used for research in the 1970s, at the University of Oregon, and in this last decade is rapidly spreading to laboratories around the world.

Many laboratories choose zebrafish because of their few ethical problems, mainly because of the use of embryos instead of adult specimens. In addition, it seems that working with this fish is very simple, and thanks to this facility, many laboratories in Euskal Herria and its surroundings work with zebrafish.

Being a relatively new animal model, it is considered necessary to unify the laboratory working methodology with this fish. In fact, each laboratory has its own way of working (anesthesia and euthanasia protocols, for example). In order to unify the working method, several companies and research centers have created a platform. Its name is <UNK> net, acronym of the scientific name of zebrafish ( Danio rerio).

<UNK> net is coordinated by AZTI-Tecnalia and is formed by the Centre for Developmental Biology of Andalusia (CABD-CSIC) and the Biomedical Research Park of Barcelona (PRBB). In the words of the coordinator of the platform, Miguel Ángel Pardo, of AZTI-Tecnalia, -coordinator of the platform -, “the main objective of the platform is that everyone who works with zebrafish have contact, unifying methodologies and extending the use of the platform to the whole state”.

The coordination of the platform is carried out at AZTI-Tecnalia and is the responsibility of Miguel Angel Pardo.

The Pardo group uses zebrafish to test new components and molecules related to food. For example, they investigate the influence of molecules that can help reduce or thin the tension or cholesterol level. But before the food department, zebrafish came to aquaculture at AZTI-Tecnalia. It was logical, if it was an appropriate model for man, so much better for other fish. Therefore, they were used to investigate resistant genes from farm fish diseases, such as turbot or trout.

The destiny of the transparent

Zebrafish is a good animal example for fish, of course, and also for man. It is a well known species, known almost entirely by the genome and whose parity with man is around 85%. In addition, its growth is fast and does not require special care, so you can work with a large number of specimens, obtaining results quickly.

But what most characterizes this fish is transparency: the embryo is transparent and therefore its interior is visible. It is therefore ideal for investigating organ growth. In fact, laboratories began to use zebrafish to investigate embryogenesis, that is, to know the origin and growth process of the embryo.

The embryo of the zebrafish is completely transparent and the internal organs are clearly visible.

AZTI-Tecnalia

In this sense, in recent months there have been two milestones in zebrafish research related to the transparency of this animal. The first is that they have recorded the birth of an embryo and the entire growth cycle (in toto, as scientists say, in its entirety). Research at the European Molecular Biology Laboratory (Germany) has spread to the four winds.

Another news related to zebrafish is that the Boston Children's Hospital has also achieved a transparent zebrafish in adulthood, so that also in adult specimens can follow the research undertaken with the embryo. This transparent zebrafish or albino is used, among other things, to investigate the development and spread of cancer.

Organ Research

As can be seen, zebrafish transparency is a special feature for research. As for growth, organs have a great interest. Well, to track the growth of an organ, the most common thing is to highlight the organ of the zebrafish embryo with a fluorescent marker. In this way you can directly observe the organ, with the help of a suitable magnifying glass and without sacrificing the animal, which is alive as it grows.

The entire embryo growth cycle has been recorded at the European Molecular Biology Laboratory (EMBL). In the image, some of the moments of growth: to the right, the image of the microscope and, to the left, represented in colors, the direction of the cell movement.

(Photo: EMBL)

In the company Biobide in Donostia-San Sebastián they work more or less like that. Zebrafish is used to test drugs. In Biobide they breed transgenic zebra fish adapted to each drug. In order to check if a drug produces side effects in the heart, embryos that have the heart highlighted with a fluorescent substance grow. In order to check if another drug influences blood vessels, GMOs grow that are highlighted.

The use of zebrafish is cheap and simple, before testing it with mice or rats, to decide whether a drug should move towards the market. In the words of Arantza Muriana, from Biobide, "it is intended that the affected agencies accept zebrafish as an animal model for pharmaceutical and biotech companies to use it to test new drugs," which is what they demand by joining forces through the <UNK> net platform.

Night Pearl and his friends

In 2003 the scandal came to the aquarist forums: Night Pearl, fluorescent zebrafish, was about to be marketed in Taiwan. Although some were supporters of this transgenic zebrafish (they saw no danger), the reproach of the opposites was more accused. In this situation, local governments had to decide whether or not to authorize the entry of fluorescent fish, which was ultimately a transgenic fish. Result: In all states, except California, they obtained authorization to sell in the United States.

Bars were sold in the store, although the price is twenty times that of a normal zebra fish. And they are still very successful in domestic aquariums. It cannot be denied that they are striking, especially at night, since when turning off the house lights the fluorescence is more evident, that is, at night they make light.

But that zebra fish was conceived for a very different function in origin. Researchers from the National University of Singapore wanted to use it as an indicator of detection of toxins in rivers, wanted a fish that would become fluorescent in the presence of toxins and the first step was to introduce the zebrafish a gene of a jellyfish with green fluorescence. Thus was born the first fluorescent zebra fish, green, with the name of Night Pearl, night pearl.

(Photo: Glo Fish®)

Starfire Red, a red fluorescent zebra fish, followed him, and just two years ago Electric Green and Sunburst Orange, green and orange, respectively. All of them with the genes of corals.

But time has not calmed the debate. Some insist that they can have effects on the environment, although zebrafish, of tropical origin, are unlikely to remain in cold waters. It seems that it is not harmful in this sense. But ethical debate is more difficult to resolve. Is it really worth genetically transforming fish to be used as mere decoration?

Moreover, someone has asked another question: and if fish suffers with this transformation? In fact, those who work in the laboratory with zebrafish know that taking care of the night and day cycles is essential for the well-being of fish. The night is dark in the laboratory, the lights in the aquarium room are not lit until the day opens. But the fluorescent zebra fish carries its own light and knows no real night.

At the moment there is no answer to these questions. But the truth is that fish are on the market, within the law in the United States and in the shade elsewhere in the world. The importation, sale or possession of these fish is prohibited in the European Union, although in the Netherlands one thousand four hundred were found in animal stores. Attraction for the forbidden? Another unanswered question.